JP7383971B2 - Resin compositions, cured resin products and composite molded bodies - Google Patents

Description

The present invention relates to a composite molded article having a resin composition, a cured resin product, a cured product portion made of the cured product of the resin composition, and a metal portion.
The resin composition, cured resin product, and composite molded article of the present invention can be suitably used, for example, as a heat dissipation sheet for power semiconductor devices.

In recent years, power semiconductor devices used in various fields such as railways, automobiles, and general home appliances have changed from conventional Si power semiconductors to SiC, AlN, GaN, etc. in order to become smaller, lower cost, and more efficient. There is a transition to power semiconductors using
A power semiconductor device is generally used as a power semiconductor module in which a plurality of semiconductor devices are arranged on a common heat sink and packaged.

Various problems have been pointed out toward the practical use of such power semiconductor devices, and one of them is the problem of heat dissipation from the devices. This problem generally affects the reliability of power semiconductor devices that can be operated at high temperatures to achieve higher output and higher density. There are concerns that heat generation associated with device switching may reduce reliability.

In recent years, heat generation due to the increased density of integrated circuits has become a major problem, particularly in the electrical and electronic fields, and how to dissipate heat has become an urgent issue.

As one method to solve this problem, a highly thermally conductive ceramic substrate such as an alumina substrate or an aluminum nitride substrate is used as a heat dissipation substrate on which a power semiconductor device is mounted. However, ceramic substrates have drawbacks such as being easily broken by impact, difficult to make thin films, and difficult to miniaturize.

Therefore, a heat dissipation sheet using a thermosetting resin such as a highly thermally conductive epoxy resin and a highly thermally conductive inorganic filler has been proposed. For example, Patent Document 1 proposes a heat dissipating resin sheet containing a resin having a Tg of 60° C. or less and a boron nitride filler, in which the content of the boron nitride filler is 30 vol% or more and 60 vol% or less. ing.

However, in conventional heat dissipating resin sheets made of inorganic filler-containing resin compositions, when laminated heat dissipating sheets are laminated with substrates such as copper foil in order to improve thermal conductivity, they are used in the manufacturing process of semiconductor devices, and even in the mounting process of semiconductor devices. There was a problem that the resin sheet would peel off from the substrate due to repeated temperature changes.
That is, semiconductor devices are usually soldered together by a reflow process for mass production, and at that time, the process of heating the device to a temperature at which the solder flows (290° C.) and then cooling it is repeated. Heating and cooling are similarly repeated when semiconductor devices are mounted. Due to such repeated temperature changes, the resin sheet and the substrate separate from each other due to the difference in thermal expansion coefficient between the resin sheet and the substrate.
In the case of a ceramic substrate, it is integrated by sintering with a copper plate, so peeling at the interface is unlikely to occur, but with a heat dissipating resin sheet, it is integrated by heating and pressing a cured film, so interfacial peeling is likely to occur.

In addition, in order to prevent interfacial peeling due to expansion and contraction, it is possible to increase the degree of crosslinking of the epoxy resin to increase the strength of the cured product, but in order to do so, it is necessary to increase the epoxy equivalent of the epoxy resin. In this case, the concentration of hydroxyl groups increases due to the addition reaction between the epoxy groups of the epoxy resin and active hydrogen, and as the concentration increases, the moisture absorption rate tends to increase. Such a method was considered undesirable because an increase in the moisture absorption rate of the epoxy resin reduces the insulation properties of the cured product and also reduces the withstand voltage performance under high temperature and high humidity conditions.

Furthermore, one of the processes for assembling power semiconductor modules is a solder reflow process, in which the temperature of the components is rapidly increased to melt the solder and join the metal components together. Another problem is that the reliability of the power semiconductor module decreases due to deterioration of the members used in the module in this reflow process, such as delamination at the interface between the cured product and the metal and a decrease in insulation performance. In addition, there is another problem in that the components absorb moisture during storage before the reflow process, which significantly accelerates component deterioration in the solder reflow process, further reducing the performance of the resulting power semiconductor module.

JP 2017-36415 Publication

The present invention provides a resin composition and a cured resin that have excellent resistance to repeated temperature changes, that is, repeated reflow resistance, and are difficult to peel off from the metal plate even when subjected to repeated temperature changes when used as a laminate with a metal plate. An object of the present invention is to provide a composite molded article using a resin cured product and a cured resin product.

As a result of repeated studies to solve the above problems, the inventor of the present invention found that a storage elastic modulus corresponding to the water absorption amount of the cured resin material (the storage elastic modulus becomes higher as the water absorption amount increases), and therefore, It has been found that repeated reflow resistance can be increased by appropriately controlling the storage modulus of a resin composition used for a cured resin product after curing, depending on the water absorption amount of the cured resin product.
The present invention has been achieved based on such knowledge, and the gist thereof is as follows.

[1] A resin composition containing a resin and an agglomerated inorganic filler, where the weight increase rate at 85°C and 85% RH after curing of the resin composition is X (wt%), and the resin excluding the inorganic filler A resin composition that satisfies the following formula (I), where Y (Pa) is the storage modulus at 200°C of a cured product of the composition.
Y>2.01×10 ⁷ X+1.3×10 ⁶ (I)

[2] The resin composition according to [1], wherein the resin composition contains an epoxy resin.

[3] The resin composition according to [1] or [2], wherein the resin composition contains an epoxy resin having three or more epoxy groups per molecule.

[4] The resin composition according to any one of [1] to [3], wherein the resin composition contains an epoxy resin having a biphenyl structure and a weight average molecular weight of 10,000 or more.

[5] The epoxy resin having a biphenyl structure and a weight average molecular weight of 10,000 or more further has at least one selected from the structure represented by the following structural formula (1) and the following structural formula (2). The resin composition according to [4], which has one structure.

(In formula (1), R ¹ and R ² each represent an organic group, and in formula (2), R ³ represents a divalent cyclic organic group.)

[6] The content of the epoxy resin having a biphenyl structure and a weight average molecular weight of 10,000 or more is 1% by weight or more and 50% by weight based on 100% by weight of the solid content in the resin composition excluding inorganic fillers. The resin composition according to [4] or [5] below.

[7] The content of the epoxy resin having three or more epoxy groups per molecule is 10% by weight or more and 50% by weight or less based on 100% by weight of solid content in the resin composition excluding inorganic fillers. The resin composition according to any one of [3] to [6].

[8] The resin composition according to any one of [3] to [7], wherein the epoxy resin having three or more epoxy groups per molecule has a molecular weight of 800 or less.

[9] The resin composition according to any one of [1] to [8], further comprising a compound having a nitrogen atom-containing heterocyclic structure.

[10] The resin composition according to any one of [1] to [9], wherein the agglomerated inorganic filler is boron nitride agglomerated particles.

[11] The resin composition according to [10], wherein the boron nitride aggregated particles have a house of cards structure.

[12] A composite molded article comprising a cured product part made of a cured product of the resin composition according to any one of [1] to [11], and a metal part.

[13] A semiconductor device comprising the composite molded article according to [12].

[14] A resin cured product using a resin composition containing a resin and an agglomerated inorganic filler, where the weight increase rate of the cured resin product at 85°C and 85% RH is X (% by weight), and the inorganic filler is A cured resin product that satisfies the following formula (I), where Y (Pa) is the storage modulus at 200°C after curing of the resin composition.
Y>2.01×10 ⁷ X+1.3×10 ⁶ (I)

According to the resin composition of the present invention, it has excellent resistance to repeated temperature changes, that is, repeated reflow resistance, and when used as a laminate with a metal plate, it is difficult to peel off from the metal plate even when subjected to repeated temperature changes. A cured resin product is provided.
The cured resin of the present invention has excellent resistance to repeated temperature changes, that is, repeated reflow resistance, and when used as a laminate with a metal plate, it is difficult to peel off from the metal plate even when subjected to repeated temperature changes.
The resin composition and cured resin product of the present invention, and a composite molded article using the cured resin product can be suitably used as a heat dissipation sheet for power semiconductor devices, and can be used to produce highly reliable power semiconductor modules. It can be realized.

Embodiments of the present invention will be described in detail below, but the present invention is not limited to the following embodiments, and can be implemented with various modifications within the scope of the gist.

[Resin composition]
The resin composition of the present invention includes a resin and an aggregated inorganic filler, and the weight increase rate at 85° C. and 85% RH after curing of the resin composition is X (% by weight), and the resin composition excluding the inorganic filler It is characterized by satisfying the following formula (I), where Y (Pa) is the storage modulus at 200° C. of the cured product.
Y>2.01×10 ⁷ X+1.3×10 ⁶ (I)

In the present invention, the "resin composition" refers to an uncured composition, for example, a composition in a state before curing in a molding and pressurizing process. More specifically, examples thereof include a slurry-like resin composition to be subjected to the coating process described below, a sheet that has undergone the coating process, and a sheet that has not yet been cured that has undergone processes such as coating and drying.

The "cured resin" of the present invention refers to a product obtained by curing the resin composition described above, and measuring the temperature from 40°C to 250°C at 10°C/min using a differential scanning calorimeter (DSC). Refers to a cured state in which the exothermic peak obtained when the temperature is raised is 10 J/g or less.

In the present invention, the resin composition excluding the inorganic filler refers to components other than the inorganic filler in the resin composition. The inorganic filler will be described later, but it includes agglomerated inorganic filler and non-agglomerated inorganic filler (non-agglomerated inorganic filler).

In the present invention, the "solid content" in the resin composition refers to all components in the resin composition other than the solvent.

The resin composition of the present invention may contain "other components" other than the resin and the agglomerated inorganic filler to the extent that the effects of the present invention are not impaired. Other components include non-agglomerated inorganic fillers, curing agents, curing catalysts, solvents, surface treatment agents such as silane coupling agents, insulating carbon components such as reducing agents, viscosity modifiers, dispersants, thixotropic agents, Examples include flame retardants, colorants, organic fillers, and organic solvents. In particular, by including a dispersant, it becomes possible to form a uniform cured resin product, and it may be possible to improve the thermal conductivity and dielectric breakdown characteristics of the resulting cured resin product. Specific examples of these "other components" that may be included in the resin composition of the present invention will be described later.

[Formula (I)]
The resin composition of the present invention includes a resin and an aggregated inorganic filler, and the weight increase rate at 85° C. and 85% RH after curing of the resin composition is X (% by weight), and the resin composition excluding the inorganic filler The following formula (I) is satisfied when the storage elastic modulus at 200° C. of the cured product is Y (Pa).
Y>2.01×10 ⁷ X+1.3×10 ⁶ (I)

The storage modulus Y (Pa) of the cured product of the resin composition excluding inorganic fillers at 200 ° C. and the weight increase rate X (wt%) at 85 ° C. and 85% RH after curing of the resin composition are: The mechanism by which a resin cured product with excellent repeated reflow resistance is achieved by satisfying the formula (I) is estimated as follows.

Normally, cured resin products absorb moisture from the air when stored at room temperature and humidity. In a reflow test, the moisture in the cured resin material evaporates rapidly, which can cause voids, defects, and peeling at the interface with the metal. Therefore, it is preferable for X to have a smaller value. In addition, regarding the stress generated in the reflow test, the strength of the resin part of the cured resin product is low, so in the reflow test, voids are generated internally, resulting in a decrease in insulation performance, and the interface between the metal and the cured resin product peels off. Sometimes I do something. Therefore, it is preferable for Y to have a larger value. Further, for example, even if the value of X is large, reflow resistance can be maintained if Y is sufficiently large, and conversely, even if the value of Y is small, reflow resistance can be maintained if the value of X is sufficiently small.
For this reason, when a laminate is made of the cured resin of the present invention, which is a cured product of the resin composition of the present invention that satisfies formula (I), and a metal plate, even when subjected to repeated temperature changes, the metal plate is It is possible to provide a laminate with a metal plate in which the cured resin of the present invention is difficult to peel off from the plate and has excellent repeated reflow resistance.

From the above viewpoint, the weight increase rate at 85°C and 85% RH after curing of the resin composition of the present invention is X (weight %), and the storage elasticity at 200°C of the cured product of the resin composition excluding inorganic fillers is When the ratio is Y (Pa), it is preferable that the Y value is larger than 2.01×10 ⁷ X+1.3×10 ⁶ .
Moreover, the Y value is preferably less than 2.01×10 ⁷ X+7.0×10 ⁸ , more preferably less than 2.01×10 ⁷ X+7.0×10 ⁷ .
When the Y value is less than the above upper limit, it is possible to suppress the internal stress that occurs through repeated reflow tests, and tends to suppress cracking of the resulting cured resin and interfacial peeling between the metal and the cured resin. be.
From the above viewpoint, it is particularly preferable that the Y value satisfies the following formula (Ia).
2.01×10 ⁷ X+7.0×10 ⁷ >Y
>2.01×10 ⁷ X+1.3×10 ⁶ (Ia)

Here, the cured product whose storage modulus at 200°C is measured is a cured product of the resin composition of the present invention excluding the inorganic filler, and its storage modulus is determined by any previously known method. Although the value may be measured by a method, specifically, it is a value measured by a method described in the Examples section below.

Further, the weight increase rate at 85° C. and 85% RH after curing of the resin composition of the present invention is measured by the method described in the Examples section below.

The storage modulus Y (Pa) at 200°C of the cured product of the resin composition of the present invention excluding the inorganic filler is 1.0 in the range satisfying the above formula (I), preferably the above formula (Ia). It is preferably at least ×10 ⁷ Pa, particularly preferably at least 1.5 × 10 ⁷ Pa. However, if the storage modulus is excessively large, the internal stress generated by repeated reflow tests will increase, causing the cured resin to crack or the interface between the metal and cured resin to separate. The upper limit of this storage modulus is 1.0×10 ⁹ Pa.
In this way, a resin composition whose storage modulus after curing can be controlled within a specific range can be achieved by introducing a rigid structure such as an aromatic ring into the components constituting the resin composition, as described below. Alternatively, this can be achieved by introducing a polyfunctional component having a plurality of reactive groups and increasing the crosslinking density of the cured product.

Further, the weight increase rate X (weight %) of the cured product of the resin composition of the present invention at 85° C. and 85% RH is 1.5% in the range satisfying the above formula (I), preferably formula (Ia). It is preferably at most 1.2%, more preferably at most 1.2%. When this weight increase rate is less than or equal to the above upper limit value, the hygroscopicity is low, and electrical resistance performance under high temperature and high humidity conditions tends to be suppressed and interfacial peeling can be suppressed. From the viewpoint of hygroscopicity, it is preferable that this weight increase rate X (weight %) is as small as possible. However, from the viewpoint of achieving both strength and insulation performance of the cured product and film formability, the lower limit is usually 0.20%.
In this way, a cured product of a resin composition whose weight increase rate at 85° C. and 85% RH is within a specific range can be obtained by, for example, adding hydrophobic components such as aliphatic skeletons and aromatic rings to the components constituting the resin composition. This can be achieved by controlling the weight increase rate by introducing a high structure. More specifically, this can be achieved by using a resin composition containing a specific epoxy resin described below in a predetermined ratio as the resin composition used for the cured resin product.

A cured product of a resin composition that satisfies the above formula (I), preferably formula (Ia), and also satisfies a suitable storage modulus and weight increase rate can be obtained by, for example, using a specific epoxy resin and a polyfunctional epoxy resin as described below. This can be achieved by using a resin composition containing a ratio of .

[Resin composition]
The resin composition of the present invention has the above-described relationship between the weight increase rate at 85°C and 85% RH of the cured product of the resin composition and the storage modulus at 200°C of the cured product of the resin composition excluding inorganic fillers. Although there is no particular restriction as long as it satisfies formula (I), preferably formula (Ia), it usually includes a resin component, a curing agent, a curing catalyst, other components used as necessary, and a coating slurry. It consists of a solvent, etc. Further, the resin composition of the present invention preferably contains a compound having a nitrogen atom-containing heterocyclic structure from the viewpoint of improving adhesion to metal.

<Resin>
The resin contained in the resin composition of the present invention may be any resin as long as it can be cured in the presence of a curing agent or a curing catalyst to obtain a cured product that satisfies the above storage modulus and weight increase rate. Not limited. In particular, a thermosetting resin is preferred from the viewpoint of ease of manufacture.

Specific examples of the thermosetting resin include epoxy resin, phenol resin, polycarbonate resin, unsaturated polyester resin, urethane resin, melamine resin, urea resin, and maleimide resin. Among these, epoxy resins are preferred from the viewpoints of viscosity, heat resistance, hygroscopicity, and handleability. Examples of the epoxy resin include epoxy group-containing silicon compounds, aliphatic epoxy resins, bisphenol A or F epoxy resins, novolak epoxy resins, alicyclic epoxy resins, glycidyl ester epoxy resins, polyfunctional epoxy resins, Examples include polymeric epoxy resins.

The resin composition of the present invention preferably contains 5% by weight or more of the resin, more preferably 30% by weight or more, and 50% by weight of the resin in 100% by weight of the solid content of the resin composition excluding inorganic fillers. It is more preferable to contain the above amount. The resin composition of the present invention more preferably contains 99% by weight or less of the resin in 100% by weight of the solid content of the resin composition excluding inorganic fillers. When the content of the resin is at least the above lower limit, moldability becomes good, and when it is at or below the above upper limit, the content of other components can be secured, and thermal conductivity tends to be improved. .

(Epoxy resin)
Epoxy resin is a general term for compounds having one or more oxirane rings (epoxy groups) in the molecule. Further, the oxirane ring (epoxy group) contained in the epoxy resin may be either an alicyclic epoxy group or a glycidyl group, but from the viewpoint of reaction rate or heat resistance, a glycidyl group is more preferable.

The epoxy resin used in the present invention may be a compound containing an aromatic oxirane ring (epoxy group). Specific examples include glycidylated bisphenols such as bisphenol A, bisphenol F, bisphenol AD, bisphenol S, tetramethylbisphenol A, tetramethylbisphenol F, tetramethylbisphenol AD, tetramethylbisphenol S, and tetrafluorobisphenol A. Bisphenol type epoxy resin, biphenyl type epoxy resin, dihydroxynaphthalene, epoxy resin glycidylated divalent phenols such as 9,9-bis(4-hydroxyphenyl)fluorene, 1,1,1-tris(4- Epoxy resins glycidylated from trisphenols such as hydroxyphenyl)methane, epoxy resins glycidylated from tetrakisphenols such as 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane, phenol novolak, cresol novolac, Examples include novolak-type epoxy resins obtained by glycidylating novolacs such as bisphenol A, novolak, and brominated bisphenol A novolak.

The resin composition of the present invention preferably contains epoxy resin in an amount of 20% by weight or more, more preferably 45% by weight or more, based on 100% by weight of all resin components contained in the resin composition of the present invention. There is no particular upper limit to the content of the epoxy resin in the resin composition of the present invention, and the epoxy resin may be contained in an amount of 100% by weight in 100% by weight of the total resin components. By including the epoxy resin in the above range, it becomes easy to increase the elasticity of the cured product of the resin composition and control the weight increase rate, and the storage elastic modulus and weight increase rate tend to fall within the above-mentioned specific ranges.

Epoxy resins suitable as the epoxy resin used in the present invention will be explained below.

((Polyfunctional epoxy resin))
The resin composition of the present invention preferably contains an epoxy resin having three or more oxirane rings (epoxy groups) in one molecule (hereinafter sometimes referred to as "polyfunctional epoxy resin").

By containing the polyfunctional epoxy resin in the resin composition of the present invention, it is possible to introduce highly polar oxirane rings (epoxy groups) at high density, thereby making it possible to introduce physical forces such as van der Waals forces and hydrogen bonds. The interaction effect increases, and the adhesion between the metal and the cured resin in the composite molded article can be improved.
In addition, by including a polyfunctional epoxy resin, the storage elastic modulus of the cured resin product after thermosetting can be increased, which allows the cured product of the resin composition to penetrate into the uneven parts of the metal that is the adherend. After that, a strong anchor effect can be developed and the adhesion between the metal and the cured resin can be improved.

From the viewpoint of increasing the storage modulus of the cured product after thermosetting, especially the storage modulus at high temperatures, which is important in cases such as power semiconductors that generate a large amount of heat, three or more oxirane rings ( Epoxy resins having epoxy groups) are preferred, and epoxy resins having 4 or more glycidyl groups in the molecule are even more preferred. By having a plurality of oxirane rings (epoxy groups), particularly glycidyl groups, in the molecule, the crosslinking density of the cured product is improved, and the resulting cured resin product has higher strength. As a result, when internal stress occurs in the cured resin product during repeated reflow tests, the cured resin product maintains its shape without deforming or breaking, thereby creating voids and other voids within the cured resin product. can be suppressed from occurring. Although there is no particular upper limit to the number of oxirane rings (epoxy groups) in one molecule of the polyfunctional epoxy resin, it is preferably 10 or less, more preferably 8 or less.

Further, the molecular weight of the polyfunctional epoxy resin is not particularly limited, but is preferably 1,000 or less, more preferably 800 or less, and even more preferably 600 or less. Further, the molecular weight of the polyfunctional epoxy resin is preferably 100 or more, more preferably 150 or more, and particularly preferably 150 to 600.

By having the number and molecular weight of oxirane rings (epoxy groups) in one molecule of the polyfunctional epoxy resin within the above range, voids such as voids in the cured resin product of the present invention are suppressed, and the formula (I) described above is suppressed. They tend to be easier to meet.
Furthermore, by improving the reactivity of the oxirane ring (epoxy group) of the epoxy resin, the amount of hydroxyl groups during the reaction can be reduced and the weight increase rate (hygroscopicity) can be suppressed. In particular, by manufacturing a resin composition by combining a specific epoxy resin described below and a polyfunctional epoxy resin, it becomes possible to achieve both high elasticity and low moisture absorption of the cured product of the resin composition.

Specifically, as the polyfunctional epoxy resin, an epoxy resin having three or more epoxy groups is preferable, and for example, EX321L, DLC301, DLC402, etc. manufactured by Nagase ChemteX can be used.

These polyfunctional epoxy resins may be used alone or in combination of two or more.

The content of the polyfunctional epoxy resin in the resin composition of the present invention is not particularly limited, but it is preferably contained at 5% by weight or more, and preferably 10% by weight in 100% by weight of the solid content of the resin composition excluding inorganic fillers. It is more preferable to contain the above amount. Further, the content is preferably 50% by weight or less, particularly preferably 10% by weight or more and 50% by weight or less. When the content of the polyfunctional epoxy resin is at least the above lower limit, the above-mentioned effects due to the inclusion of the polyfunctional epoxy resin can be effectively obtained. On the other hand, by setting the content of the polyfunctional epoxy resin at or below the above upper limit, it is possible to suppress the hygroscopicity of the cured resin product and to improve the strength performance of the cured resin product, making it possible to achieve both of these properties. becomes.

((Specified epoxy resin))
The resin in the resin composition of the present invention preferably contains an epoxy resin having a biphenyl structure and a weight average molecular weight of 10,000 or more (hereinafter sometimes referred to as "specific epoxy resin").

In addition, in the following, the "organic group" may be any group as long as it contains a carbon atom. Examples of the organic group include an alkyl group, an alkenyl group, an aryl group, and the like, which may be substituted with a halogen atom, a group having a hetero atom, or another hydrocarbon group.

The specific epoxy resin having a biphenyl structure and a weight average molecular weight of 10,000 or more preferably has a structure represented by the following structural formula (1) (hereinafter sometimes referred to as "structure (1)") and a structure represented by the following structural formula (1). It is preferable to further have at least one structure selected from the structure represented by Structural Formula (2) (hereinafter sometimes referred to as "Structure (2)").

(In formula (1), R ¹ and R ² each represent an organic group, and in formula (2), R ³ represents a divalent cyclic organic group.)

In addition, a specific epoxy resin having a biphenyl structure and a weight average molecular weight of 10,000 or more has a structure represented by the following structural formula (3) (hereinafter sometimes referred to as "Structure (3)"). It is preferable.

(In formula (3), R ⁴ , R ⁵ , R ⁶ , and R ⁷ each independently represent an organic group with a molecular weight of 15 or more.)

In the above formula (1), at least one of R ¹ and R ² is preferably an organic group having a molecular weight of 16 or more, particularly a molecular weight of 16 to 1,000. Examples include alkyl groups such as ethyl group, propyl group, butyl group, pentyl group, hexyl group, and heptyl group, and aryl groups such as phenyl group, tolyl group, xylyl group, naphthyl group, and fluorenyl group.

R ¹ and R ² may both be organic groups with a molecular weight of 16 or more, one of which may be an organic group with a molecular weight of 16 or more, and the other may be an organic group with a molecular weight of 15 or less or a hydrogen atom. Preferably, one of R ¹ and R ² is an organic group with a molecular weight of 16 or more and the other is an organic group with a molecular weight of 15 or less, and it is particularly preferable that one of them is a methyl group and the other is a phenyl group. These groups facilitate control of handling properties such as resin viscosity, and tend to improve the strength of cured resin products.

In formula (2), R ³ is a divalent cyclic organic group, which may be an aromatic ring structure such as a benzene ring structure, a naphthalene ring structure, or a fluorene ring structure, or an aromatic ring structure such as cyclobutane, cyclopentane, or cyclohexane. It may also be an aliphatic ring structure. Moreover, they may independently have a substituent such as a hydrocarbon group or a halogen atom.

The divalent bonding portion of R ³ may be a divalent group located on a single carbon atom or may be a divalent group located on different carbon atoms. Preferred examples include divalent aromatic groups having 6 to 100 carbon atoms and divalent groups derived from cycloalkanes having 2 to 100 carbon atoms, such as cyclopropane and cyclohexane. In particular, R ³ is a 3,3,5-trimethyl-1,1-cyclohexylene group represented by the following structural formula (4), from the viewpoint of controlling handleability such as resin viscosity and the strength of the cured product. preferable.

In formula (3), R ⁴ , R ⁵ , R ⁶ , and R ⁷ are each independently an organic group having a molecular weight of 15 or more. Preferably, it is an alkyl group with a molecular weight of 15 to 1000, and in particular, all of R ⁴ , R ⁵ , R ⁶ , and R ⁷ are methyl groups, from the viewpoint of controlling handleability such as resin viscosity and the strength of the cured product. preferable.

The specific epoxy resin is preferably an epoxy resin containing one of structure (1) and structure (2) and a biphenyl structure, particularly one of structure (1) and structure (2) and structure ( More preferably, it is an epoxy resin containing 3). When the specific epoxy resin contains these structures, it tends to be possible to suppress the hygroscopicity of the cured product and maintain the strength of the resin composition.

These specific epoxy resins contain more hydrophobic hydrocarbons and aromatic structures than general epoxy resins having a bisphenol A skeleton or bisphenol F skeleton, so by blending the specific epoxy resin, The amount of moisture absorbed by the cured product of the resin composition can be reduced.
Moreover, from the viewpoint of reducing the amount of moisture absorption, it is preferable that the specific epoxy resin contains a large amount of hydrophobic structures (1), (2), and (3).

The weight average molecular weight of the specific epoxy resin is preferably 10,000 or more, more preferably 20,000 or more, and even more preferably 25,000 or more. Further, it is preferably 80,000 or less, more preferably 70,000 or less, and particularly preferably 25,000 or more and 70,000 or less.

Further, the specific epoxy resin is preferably more hydrophobic, and the epoxy equivalent is preferably larger. Specifically, the epoxy equivalent of the specific epoxy resin is preferably 3,000 g/equivalent or more, more preferably 4,000 g/equivalent or more, and even more preferably 5,000 g/equivalent or more. Further, the epoxy equivalent of the specific epoxy resin is preferably 20,000 g/equivalent or less, and more preferably 5,000 g/equivalent or more and 20,000 g/equivalent or less.

Here, the weight average molecular weight of the epoxy resin is a polystyrene equivalent value measured by gel permeation chromatography.
Further, the epoxy equivalent is defined as "the weight of the epoxy resin containing 1 equivalent of epoxy group", and can be measured according to JIS K7236.

Only one type of such specific epoxy resin may be used, or two or more types may be used in combination. The specific epoxy resin may have multiple epoxy groups.

The content of the specific epoxy resin in the resin composition of the present invention is not particularly limited, but is preferably 5% by weight or more, more preferably 10% by weight or more based on 100% by weight of the solid content of the resin composition excluding inorganic fillers. Further, it is preferably 50% by weight or less, more preferably 40% by weight or less. When the content of the specific epoxy resin is at most the above upper limit, the storage modulus of the cured product tends to be improved or maintained, and the reflow resistance tends to improve. When the content of the specific epoxy resin is at least the above lower limit, the resin composition can be easily applied, and the resulting cured resin product tends to have flexibility.

((Content ratio of specific epoxy resin and polyfunctional epoxy resin))
In the resin composition of the present invention, containing both a specific epoxy resin and a polyfunctional epoxy resin as the epoxy resin balances high elasticity and low moisture absorption of the cured product of the resin composition, and the formula ( I), preferably satisfying the above formula (Ia).

When the resin composition of the present invention contains both a specific epoxy resin and a polyfunctional epoxy resin, the content ratio of the specific epoxy resin and the polyfunctional epoxy resin is not particularly limited, but specific epoxy resin: polyfunctional epoxy resin = The ratio is preferably 10-90:90-10 (weight ratio), more preferably 20-80:80-20 (weight ratio), and 30-70:70-30 (weight ratio). Particularly preferred.

((Other epoxy resins))
The resin composition of the present invention may contain epoxy resins other than the specific epoxy resin and polyfunctional epoxy resin. The epoxy resin other than the specific epoxy resin and polyfunctional epoxy resin contained in the resin composition of the present invention is not particularly limited, but for example, glycidylated bisphenols such as bisphenol A epoxy resin and bisphenol F epoxy resin are used. Various bisphenol-type epoxy resins, various biphenyl-type epoxy resins obtained by glycidylating biphenyls, aromatic compounds having two hydroxyl groups such as dihydroxynaphthalene, 9,9-bis(4-hydroxyphenyl)fluorene, etc. Epoxy resins prepared by glycidylation of trisphenols such as 1,1,1-tris(4-hydroxyphenyl)methane, and tetrakis-based epoxy resins such as 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane. One or two types selected from epoxy resins in which phenols are glycidylated, novolak-type epoxy resins in which novolacs are glycidylated, such as phenol novolak, cresol novolac, bisphenol A novolac, and brominated bisphenol A novolak, and silicone-containing epoxy resins. The above is preferable.

<Inorganic filler>
In the present invention, the inorganic filler includes an agglomerated inorganic filler and a non-agglomerated inorganic filler.

The resin composition of the present invention contains an aggregated inorganic filler.
The resin composition of the present invention may contain a non-agglomerated inorganic filler in addition to the agglomerated inorganic filler. The non-agglomerated inorganic filler also includes the spherical filler described below.

By containing the agglomerated inorganic filler in the resin composition of the present invention, it becomes possible to improve the thermal conductivity and insulation properties of the cured resin product and to control the coefficient of linear expansion. In particular, in the pressurization step described below, the aggregated inorganic fillers are deformed by contacting each other, and by contacting on the surface, more heat conduction paths are formed, and a cured resin product with high thermal conductivity can be obtained. Moreover, by deforming the aggregated inorganic filler, gaps or voids between the fillers can be effectively removed, and insulation properties are improved.

The resin composition of the present invention contains a resin and an inorganic filler, and by using the above-mentioned epoxy resin suitable for the present invention in combination with an agglomerated inorganic filler, even after the agglomerated inorganic filler is deformed in the pressurizing step described below, The deformed state of the filler can be maintained. Furthermore, since the weight increase rate after curing of the resin composition of the present invention is within the above-mentioned specific range, the deformed state of the filler can be maintained even after the moisture absorption reflow process.

When the resin composition and cured resin material contain only a single filler such as silica or alumina, the contact between the fillers becomes point contact even after the pressurization process, effectively forming a heat conduction path. I can't. Furthermore, there are cases in which the insulation properties are lowered because voids or gaps between the fillers cannot be removed.

The aggregation form of the agglomerated inorganic filler can be confirmed using a scanning electron microscope (SEM).

(agglomerated inorganic filler)
As the agglomerated inorganic filler, an electrically insulating filler can be used, and examples thereof include those composed of at least one kind of inorganic particles selected from the group consisting of metal carbides, metal oxides, and metal nitrides.

Examples of metal carbides include silicon carbide, titanium carbide, tungsten carbide, and the like.
Examples of metal oxides include magnesium oxide, aluminum oxide, silicon oxide, calcium oxide, zinc oxide, yttrium oxide, zirconium oxide, cerium oxide, ytterbium oxide, and sialon (ceramics made of silicon, aluminum, oxygen, and nitrogen). Can be mentioned.
Examples of metal nitrides include boron nitride, aluminum nitride, silicon nitride, and the like.

In particular, when used in applications that require insulation, such as power semiconductors, agglomerated inorganic fillers have excellent insulation properties with a volume resistivity of 1×10 ¹³ Ω・cm or more, especially 1×10 ¹⁴ Ω・cm or more. Preferably, it is made of an inorganic compound. Among these, the inorganic particles constituting the aggregated inorganic filler are preferably made of metal oxide and/or metal nitride, since the cured resin has sufficient electrical insulation properties.

Examples of such metal oxides and metal nitrides include alumina (Al ₂ O ₃ , volume resistivity 1×10 ¹⁴ Ω・cm), aluminum nitride (AlN, volume resistivity 1×10 ¹⁴ Ω・cm), cm), boron nitride (BN, volume resistivity 1×10 ¹⁴ Ω・cm), silicon nitride (Si ₃ N ₄ , volume resistivity 1×10 ¹⁴ Ω・cm), silica (SiO ₂ , volume resistivity 1× 10 ¹⁴ Ω·cm), among which alumina, aluminum nitride, boron nitride, and silica are preferred, and alumina and boron nitride are particularly preferred.

There are no particular limitations on the method or degree of aggregation of the agglomerated inorganic filler.
The agglomerated inorganic filler may be surface-treated with a surface-treating agent. As the surface treatment agent, a known surface treatment agent can be used.

One kind of agglomerated inorganic filler may be used alone, or two or more kinds of agglomerated inorganic fillers may be used as a mixture in any combination and ratio.

As the agglomerated inorganic filler, it is preferable to use the following boron nitride agglomerated particles from the viewpoint of effectively exhibiting the above-mentioned effects by using the agglomerated inorganic filler. Boron nitride aggregate particles may be used in combination with inorganic fillers of different shapes and types.

(Boron nitride aggregate particles)
Boron nitride has high thermal conductivity, but since it is scaly, it has excellent thermal conductivity in the plane direction, but has high thermal resistance in the direction perpendicular to the plane. Agglomerated particles obtained by collecting such scale-like particles and agglomerating them into a spherical shape are preferable because they are easy to handle.

In boron nitride agglomerated particles in which boron nitride particles are stacked like a cabbage, the radial direction of the agglomerated particles is the direction in which the thermal resistance is large.
The boron nitride agglomerated particles are preferably those in which boron nitride particles are aligned in the plane direction so that the radial direction of the agglomerated particles is the direction of good heat conduction.

The boron nitride agglomerated particles also preferably have a house of cards structure.
The "card house structure" is, for example, Ceramics 43 No. 2 (published by the Japan Ceramics Association in 2008), and has a structure in which plate-shaped particles are not oriented and are laminated in a complicated manner. More specifically, boron nitride agglomerated particles having a card house structure are aggregates of boron nitride primary particles in which the flat parts and end faces of the primary particles are in contact to form, for example, a T-shaped aggregate. These are boron nitride agglomerated particles with a structure of

As the boron nitride agglomerated particles used in the present invention, boron nitride agglomerated particles having the above-mentioned house of cards structure are particularly preferable. By using boron nitride agglomerated particles having a card house structure, thermal conductivity can be further increased.

The new Mohs hardness of the boron nitride agglomerated particles is not particularly limited, but is preferably 5 or less. There is no particular lower limit to the new Mohs hardness of the boron nitride agglomerated particles, but it is, for example, 1 or more.

When the new Mohs hardness is 5 or less, the contact between particles dispersed in the resin composition tends to be surface contact, forming heat conduction paths between particles, and the heat conduction of the cured resin tends to improve. be.

The volume average particle diameter of the boron nitride agglomerated particles is not particularly limited, but is preferably 10 μm or more, more preferably 15 μm or more. The volume average particle diameter of the boron nitride agglomerated particles is preferably 100 μm or less, more preferably 90 μm or less. When the volume average particle diameter is equal to or larger than the above lower limit, interparticle interfaces are suppressed in the resin composition and cured resin, thereby reducing thermal resistance and tending to provide high thermal conductivity. When the volume average particle diameter is equal to or less than the above upper limit, surface smoothness of the cured resin product tends to be obtained.

The volume average particle diameter of boron nitride aggregated particles means the particle diameter when the cumulative volume becomes 50% when a cumulative curve is drawn with the volume of the powder subjected to measurement as 100%.
The volume average particle diameter is measured using a laser diffraction/scattering particle size distribution analyzer on a sample in which aggregated particles are dispersed in a pure water medium containing sodium hexametaphosphate as a dispersion stabilizer. Examples include a wet measurement method and a dry measurement method using "Morphologi" manufactured by Malvern.
The same applies to the volume average particle diameter of the spherical inorganic filler described below.

(Content of agglomerated inorganic filler)
The content of the agglomerated inorganic filler in the resin composition of the present invention is preferably 30% by weight or more, more preferably 40% by weight or more, and 45% by weight based on 100% by weight of the solid content of the resin composition. It is more preferable that it is above. Further, the content of the agglomerated inorganic filler in the resin composition of the present invention is preferably 99% by weight or less, more preferably 90% by weight or less, and 80% by weight or less based on 100% by weight of the solid content of the resin composition. % or less is more preferable. When the content of the agglomerated inorganic filler is equal to or higher than the above lower limit, it tends to be possible to sufficiently obtain the effect of improving thermal conductivity and the effect of controlling the coefficient of linear expansion due to the inclusion of the agglomerated inorganic filler. When the content of the aggregated inorganic filler is at most the above upper limit, the moldability of the resin composition and cured resin product and the interfacial adhesion in the composite molded product tend to improve.

(Non-agglomerated inorganic filler)
The resin composition of the present invention may contain an agglomerated inorganic filler and a non-agglomerated inorganic filler as an inorganic filler.

The non-agglomerated inorganic filler preferably has a thermal conductivity of 10 W/m·K or more, preferably 15 W/m·K or more, more preferably 20 W/m·K or more, for example 20 to 30 W/m·K, Examples include spherical inorganic fillers having a new Mohs hardness of 3.1 or more, for example 5 to 10. By using such a spherical inorganic filler in combination with the above-mentioned agglomerated inorganic filler, it is possible to improve the adhesion to metal and heat dissipation of the resulting cured resin product.

Here, "spherical" may be anything that is generally recognized as spherical; for example, an average circularity of 0.4 or more may be considered spherical, or an average circularity of 0.6 or more may be considered spherical. Usually, the upper limit of the average circularity is 1. Circularity can be measured by image processing the projected image, and can be measured using, for example, Sysmex's FPIA series.

The spherical inorganic filler is preferably at least one selected from the group consisting of alumina, synthetic magnesite, silica, aluminum nitride, silicon nitride, silicon carbide, zinc oxide, and magnesium oxide. By using these preferred spherical inorganic fillers, the heat dissipation properties of the resulting cured resin product can be further improved.

The volume average particle diameter of the spherical inorganic filler is preferably in the range of 0.5 μm or more and 40 μm or less. It is thought that by having a volume average particle diameter of 0.5 μm or more, the resin and inorganic filler can easily flow during heat molding, and the interfacial adhesive force in the composite molded article of the present invention can be increased. Moreover, since the average particle diameter is 40 μm or less, it becomes easier to maintain the dielectric breakdown characteristics of the cured resin material.

When an agglomerated inorganic filler and a non-agglomerated inorganic filler are used together as the inorganic filler, the content ratio of the agglomerated inorganic filler and the non-agglomerated inorganic filler in the resin composition is not particularly limited, but the weight ratio is 90:10 to 10. :90 is preferable, and 80:20 to 20:80 is more preferable.

Further, the total content of the agglomerated inorganic filler and the non-agglomerated inorganic filler in the resin composition of the present invention is preferably 30% by weight or more, and 40% by weight or more in 100% by weight of the solid content of the resin composition. More preferably, it is 50% by weight or more. Further, the total content of the agglomerated inorganic filler and the non-agglomerated inorganic filler in the resin composition of the present invention is preferably 99% by weight or less, and 90% by weight or less based on 100% by weight of the solid content of the resin composition. It is more preferable that the amount is 80% by weight or less.

<Other ingredients>
The resin composition of the present invention may contain other components other than those mentioned above, within a range that does not impair the effects of the present invention. Other components include a compound having a heterocyclic structure containing a nitrogen atom, a curing agent, a curing catalyst, a surface treatment agent such as a silane coupling agent that improves the interfacial adhesive strength between the inorganic filler and the resin, and a reducing agent. Examples include an insulating carbon component, a viscosity modifier, a dispersant, a thixotropic agent, a flame retardant, a coloring agent, an organic filler, an organic solvent, and a thermoplastic resin.
The presence or absence and content ratio of other components in the resin composition of the present invention are not particularly limited as long as they do not significantly impair the effects of the present invention.

(Compound having a heterocyclic structure containing a nitrogen atom)
The resin composition of the present invention may contain a compound having a nitrogen atom-containing heterocyclic structure (hereinafter sometimes referred to as a "nitrogen-containing heterocyclic compound").

By containing the nitrogen-containing heterocyclic compound, the effect of improving the adhesiveness between the cured resin material obtained from the resin composition of the present invention and metal tends to be exhibited. That is, the nitrogen-containing heterocyclic compound improves the adhesion between the resin composition or cured resin and the metal by being located at the interface when the resin composition or cured resin is composited with a metal. . From this point of view, the nitrogen-containing heterocyclic compound preferably has a low molecular weight in order to make it easier for the nitrogen-containing heterocyclic compound to stay at the interface between the resin composition or cured resin and the metal.
The molecular weight of the nitrogen-containing heterocyclic compound is preferably 1,000 or less, more preferably 500 or less. The lower limit of the molecular weight of the nitrogen-containing heterocyclic compound is not particularly limited, but is preferably 60 or more, more preferably 70 or more.

Examples of the heterocyclic structure of the nitrogen-containing heterocyclic compound include structures derived from imidazole, triazine, triazole, pyrimidine, pyrazine, pyridine, and azole.
The nitrogen-containing heterocyclic compound may have a plurality of heterocyclic structures in one molecule at the same time.
From the viewpoint of improving the insulation properties of the resin composition and the adhesion to metals, imidazole compounds and triazine compounds are preferable as the nitrogen-containing heterocyclic compound.

Preferred imidazole compounds and triazine compounds as nitrogen-containing heterocyclic compounds include, for example, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino -6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1') ]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2,4 -Diamino-6-vinyl-s-triazine, 2,4-diamino-6-vinyl-s-triazine isocyanuric acid adduct, 2,4-diamino-6-methacryloyloxyethyl-s-triazine, 2,4-diamino Examples include -6-methacryloyloxyethyl-s-triazine isocyanuric acid adduct.

Among these, the high resin compatibility and high reaction activation temperature make it possible to easily adjust the curing speed and physical properties after curing, which improves the storage stability of resin compositions and facilitates thermoforming. In particular, those having a structure derived from imidazole and those having a structure derived from triazine are particularly preferable, and those having a structure derived from triazine are particularly preferable, since the adhesive strength can be further improved afterwards. The heterocyclic structure of the nitrogen-containing heterocyclic compound is particularly preferably a structure derived from 1,3,5-triazine. Further, it is also possible to have a plurality of these illustrated structural parts.

Note that the nitrogen-containing heterocyclic compound may contain a curing catalyst, which will be described later, depending on the structure. Therefore, the resin composition of the present invention can contain the nitrogen-containing heterocyclic compound as a curing catalyst.

Only one type of nitrogen-containing heterocyclic compound may be used, or two or more types may be used in combination.

The content of the nitrogen-containing heterocyclic compound is preferably 0.001% by weight or more, and preferably 0.01% by weight or more in 100% by weight of the solid content of the resin composition of the present invention excluding inorganic fillers. The content is more preferably 0.1% by weight or more, even more preferably 0.5% by weight or more. Further, the content of the nitrogen-containing heterocyclic compound is preferably 10% by weight or less, more preferably 7% by weight or less in 100% by weight of the solid content of the resin composition of the present invention excluding inorganic fillers. , more preferably 5% by weight or less. In particular, it is preferably contained in an amount of 0.5 to 5% by weight. When the curing catalyst described below is included in the nitrogen-containing heterocyclic compound due to its molecular structure, the total amount including the content thereof is preferably included in the above range. When the content of the nitrogen-containing heterocyclic compound is at least the above-mentioned lower limit, the above-mentioned effects due to the inclusion of this compound can be sufficiently obtained, and when it is below the above-mentioned upper limit, the reaction proceeds effectively and the crosslinking density is improved. This can increase strength and improve storage stability.

(hardening agent)
The resin composition of the present invention may contain a curing agent.

The curing agent is not particularly limited, but preferred curing agents are phenolic resins, acid anhydrides having an aromatic skeleton or alicyclic skeleton, or water additives of the acid anhydrides or modified products of the acid anhydrides. . By using these preferred curing agents, it is possible to obtain a cured resin product with an excellent balance of heat resistance, moisture resistance, and electrical properties. Only one type of curing agent may be used, or two or more types may be used in combination.

The phenol resin is not particularly limited. Specific examples of phenolic resins include phenol novolak, o-cresol novolak, p-cresol novolak, t-butylphenol novolak, dicyclopentadiene cresol, polyparavinylphenol, bisphenol A type novolak, xylylene-modified novolak, decalin-modified novolak, poly Examples include (di-o-hydroxyphenyl)methane, poly(di-m-hydroxyphenyl)methane, and poly(di-p-hydroxyphenyl)methane. Among these, novolak-type phenolic resins with a rigid main chain skeleton and phenols with a triazine skeleton are used to further improve the flexibility and flame retardancy of resin compositions, and to improve the mechanical properties and heat resistance of cured resin products. Resins are preferred. Further, in order to improve the flexibility of an uncured resin composition and the toughness of a cured resin product, a phenol resin having an allyl group is preferable.

Commercially available phenolic resins include MEH-8005, MEH-8000H, and NEH-8015 (all manufactured by Meiwa Kasei), YLH903 (manufactured by Mitsubishi Chemical), LA-7052, LA-7054, LA-7751, and LA. -1356 and LA-3018-50P (both manufactured by Dainippon Ink Co., Ltd.), as well as PSM6200, PS6313 and PS6492 (manufactured by Gunei Chemical Industry Co., Ltd.).

The acid anhydride having an aromatic skeleton, the water additive of the acid anhydride, or the modified product of the acid anhydride are not particularly limited. Specific examples include SMA Resin EF30 and SMA Resin EF60 (all manufactured by Sartomer Japan), ODPA-M and PEPA (all manufactured by Manac), Rikagit MTA-10, Rikagit TMTA, and Rikagit TMEG-. 200, Rikajit TMEG-500, Rikajit TMEG-S, Rikajit TH, Rikajit MH-700, Rikajit MT-500, Rikajit DSDA and Rikajit TDA-100 (all manufactured by Shinnihon Rika Co., Ltd.), EPICLON B4400, and EPICLON B570 ( All of the above are manufactured by Dainippon Ink Chemical Co., Ltd.).

An acid anhydride having an alicyclic skeleton, a water additive of the acid anhydride, or a modified product of the acid anhydride is an acid anhydride having a polyalicyclic skeleton, a water additive of the acid anhydride, or a modified product of the acid anhydride. It is a modified anhydride, an acid anhydride with an alicyclic skeleton obtained by addition reaction of a terpene compound and maleic anhydride, a water additive of the acid anhydride, or a modified product of the acid anhydride. is preferred. Specific examples include Licasit HNA and Licasit HNA-100 (all manufactured by Shin Nippon Chemical Co., Ltd.), Epicure YH306 and Epicure YH309 (both manufactured by Mitsubishi Chemical Corporation), and the like.

The presence or absence of a curing agent in the resin composition of the present invention is not particularly limited. Moreover, when the resin composition of the present invention contains a curing agent, the content of the curing agent is not particularly limited.

When the resin composition of the present invention contains a curing agent, it is preferably contained in 70% by weight or less, especially 55% by weight or less in 100% by weight of the solid content of the resin composition excluding inorganic fillers.
Further, the content of the curing agent in the resin composition of the present invention is preferably 70% equivalent or less, more preferably 55% equivalent or less, and 45% equivalent or less based on the total epoxy equivalent in the resin composition. More preferred.
When the content of the curing agent is below the above upper limit, the reaction proceeds effectively, the crosslinking density can be improved, the strength can be increased, and the film formability is further improved.

(curing catalyst)
The resin composition of the present invention may contain a curing catalyst. In order to adjust the curing speed and physical properties of the cured product, it is preferable to contain a curing catalyst together with the curing agent.

The curing catalyst is not particularly limited, but is appropriately selected depending on the type of resin and curing agent used. Specific examples of the curing catalyst include diazabicycloalkenes such as chain or cyclic tertiary amines, organic phosphorus compounds, quaternary phosphonium salts, and organic acid salts. Furthermore, organic metal compounds, quaternary ammonium salts, metal halides, and the like can also be used.
Examples of the organometallic compounds include zinc octylate, tin octylate, and aluminum acetylacetone complex.
These may be used alone or in combination of two or more.

When the resin composition of the present invention contains a curing catalyst, the curing catalyst is contained in an amount of 0.1 to 10% by weight, particularly 0.1 to 5% by weight in 100% by weight of the solid content of the resin composition excluding inorganic fillers. It is preferable that When the content of the curing catalyst is at least the above lower limit, the progress of the curing reaction can be sufficiently promoted to achieve good curing. When the content of the curing catalyst is below the above upper limit, the curing speed will not be too fast, and therefore the storage stability of the resin composition of the present invention can be made good.

(solvent)
The resin composition of the present invention may contain an organic solvent, for example, in order to improve coating properties when molding a sheet-like cured resin material through a coating process.

Examples of organic solvents that may be contained in the resin composition of the present invention include methyl ethyl ketone, cyclohexanone, propylene glycol monomethyl ether acetate, butyl acetate, isobutyl acetate, propylene glycol monomethyl ether, and the like.
These organic solvents may be used alone or in combination of two or more.

When the resin composition of the present invention contains an organic solvent, the content is appropriately determined depending on the handleability of the resin composition when producing a cured resin product, the shape before curing, drying conditions, etc.
When the resin composition of the present invention is in the form of a slurry to be subjected to the coating process described below, the organic solvent should be used such that the solid content concentration of the resin composition of the present invention is 10 to 90% by weight, particularly 40 to 80% by weight. It is preferable to use
When the resin composition of the present invention is in the form of a sheet that has undergone processes such as coating and drying, the solid content concentration of the resin composition of the present invention is preferably 95% by weight or more, particularly 98% by weight or more. is more preferable.

(dispersant)
The resin composition of the present invention may contain a dispersant. When the resin composition of the present invention contains a dispersant, it becomes possible to form a uniform cured resin product, and the thermal conductivity and dielectric breakdown characteristics of the resulting cured resin product can be improved. There is.

The dispersant preferably has a functional group containing a hydrogen atom having hydrogen bonding properties. When the dispersant has a functional group containing a hydrogen atom having hydrogen bonding properties, the thermal conductivity and dielectric breakdown characteristics of the resulting cured resin product can be further improved. Examples of the functional group containing a hydrogen atom having hydrogen bonding properties include a carboxyl group (pKa=4), a phosphoric acid group (pKa=7), and a phenol group (pKa=10).

The pKa of the functional group containing a hydrogen atom having hydrogen bonding properties is preferably within the range of 2 to 10, more preferably within the range of 3 to 9. When the pKa is 2 or more, the acidity of the dispersant falls within an appropriate range, and the reaction of the epoxy resin in the resin component may be easily suppressed. Therefore, when an uncured molded product is stored, storage stability tends to be improved. When the pKa is 10 or less, the function as a dispersant is sufficiently fulfilled, and the thermal conductivity and dielectric breakdown characteristics of the cured resin material tend to be sufficiently improved.

The functional group containing a hydrogen atom having hydrogen bonding properties is preferably a carboxyl group or a phosphoric acid group. In this case, the thermal conductivity and dielectric breakdown characteristics of the cured resin material can be further improved.

Examples of dispersants include polyester carboxylic acids, polyether carboxylic acids, polyacrylic carboxylic acids, aliphatic carboxylic acids, polysiloxane carboxylic acids, polyester phosphoric acids, polyether phosphoric acids, Examples include polyacrylic phosphoric acid, aliphatic phosphoric acid, polysiloxane phosphoric acid, polyester phenol, polyether phenol, polyacrylic phenol, and polysiloxane phenol.
Only one type of dispersant may be used, or two or more types may be used in combination.

(Organic filler/thermoplastic resin)
The resin composition of the present invention may contain an organic filler and/or a thermoplastic resin. By including the organic filler and thermoplastic resin in the resin composition of the present invention, appropriate elongation is imparted to the resin composition, the stress generated is alleviated, and the occurrence of cracks in the temperature cycle test can be suppressed. There are cases where it is possible.

As the thermoplastic resin, any generally known thermoplastic resin can be used. Examples of thermoplastic resins include vinyl polymers such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, (meth)acrylic resin, ethylene-vinyl acetate copolymer, and ethylene-vinyl alcohol copolymer, polylactic acid resin, and polyethylene terephthalate. , polyester such as polybutylene terephthalate, nylon, polyamide such as polyamide amine, polyvinyl acetal resin such as polyvinyl acetoacetal, polyvinyl benzal, polyvinyl butyral resin, ionomer resin, polyphenylene ether, polyphenylene sulfide, polycarbonate, polyether ether ketone, polyacetal , ABS resin, LCP (liquid crystal polymer), fluororesin, urethane resin, silicone resin, various elastomers, and modified products of these resins.

The thermoplastic resin may be uniform in the resin phase of the cured resin product, or may be phase-separated and its shape can be recognized. In the case where the thermoplastic resin undergoes phase separation, the shape of the thermoplastic resin in the cured resin product may be particulate or fibrous. In this way, when the shape of a thermoplastic resin is recognized in a cured resin product, the thermoplastic resin may be recognized as an organic filler. Thermoplastic resins are not included in organic fillers.

When the thermoplastic resin or organic filler is insoluble in the above-mentioned resin, it is possible to prevent the viscosity of the resin composition from increasing and, for example, to improve the smoothness of the sheet surface when molded into a sheet as described below. can. In this case, by mixing the thermoplastic resin and organic filler that are insoluble in the aforementioned resin at the same time as a large amount of inorganic filler, the component phase that is thermoplastic and has good elongation can be efficiently dispersed in the cured resin. Easy to relieve stress. Therefore, it is possible to suppress the occurrence of cracks in the cured resin material without lowering the elastic modulus of the cured resin material.
From these viewpoints, as the thermoplastic resin, polyamide resins such as nylon, cellulose resins, etc. are preferable, and polyamide resins such as nylon are particularly preferable.

When the shape of the thermoplastic resin that can be observed in the cured resin product is particulate, the upper limit of the average particle size is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 30 μm or less. be. By controlling the average particle diameter of the particulate thermoplastic resin in the resin cured product to be equal to or less than the above upper limit, sheet-shaped cured products of various thicknesses can be created without causing a decrease in thermal conductivity.
The average particle diameter of the particulate thermoplastic resin is determined by observing the cross section of the cured resin material and determining the average value of the longest diameters of 20 arbitrary particles.

[Cured resin product]
The cured resin product of the present invention is a cured resin product using a resin composition containing a resin and an agglomerated inorganic filler, and the weight increase rate of the cured resin product at 85° C. and 85% RH is expressed as X (wt%). is characterized in that it satisfies the following formula (I), where Y (Pa) is the storage modulus at 200° C. after curing of the resin composition excluding inorganic fillers.
Y>2.01×10 ⁷ X+1.3×10 ⁶ (I)

In the present invention, the term "resin composition" refers to an uncured resin composition containing an aggregated inorganic filler and a resin. Although not particularly limited, it is preferably a mixture of a thermosetting resin component such as an agglomerated inorganic filler and an epoxy resin, a curing agent for curing it, a curing catalyst serving as a curing aid, etc. It is more preferable to contain a compound having a ring structure.
Moreover, the resin composition excluding inorganic filler refers to components other than the inorganic filler in the resin composition. The resin, curing agent, curing catalyst, compound having a heterocyclic structure containing a nitrogen atom, inorganic filler, inorganic agglomerated filler, and other components are the same as those for the resin composition described above, and the preferred ranges are also the same.

The "cured resin product" of the present invention refers to a product obtained by curing a resin composition. Furthermore, the cured resin of the present invention has an exothermic peak of 10 J/g or less when heated by DSC from 40° C. to 250° C. at a rate of 10° C./min.

The method for obtaining the cured resin of the present invention is not particularly limited. For example, there is a method of curing the resin composition described above.

The cured resin product of the present invention is preferably obtained by curing the resin composition of the present invention described above, and the weight increase rate and the resin composition excluding the inorganic filler constituting the cured resin product of the present invention are The storage modulus of the material after curing is as explained in the resin composition of the present invention described above.

<Storage modulus and weight increase rate>
The cured resin product of the present invention has a weight increase rate of X (% by weight) at 85° C. and 85% RH, and an inorganic filler from a resin composition containing a resin used for the cured resin product and an agglomerated inorganic filler. The following formula (I) is satisfied when the storage elastic modulus at 200° C. of the cured product of the resin composition excluding the above is defined as Y (Pa).
Y>2.01×10 ⁷ X+1.3×10 ⁶ (I)
In the above formula (I), the Y value is preferably less than 2.01×10 ⁷ X+7.0×10 ⁸ , more preferably less than 2.01×10 ⁷ X+7.0×10 ⁷ , Particularly preferred are those that satisfy the following formula (Ia).
2.01×10 ⁷ X+7.0×10 ⁷ >Y
>2.01×10 ⁷ X+1.3×10 ⁶ (Ia)

By being within the above range, it is possible to suppress the internal stress generated by repeated reflow tests from becoming excessive, and it tends to suppress cracking of the obtained cured resin product and interfacial peeling between the metal and the cured resin product. be. In addition, within the above range, the cured resin can easily enter the uneven parts of the metal, which is the adherend, which will be described later. There is a tendency for adhesion to improve.

In this way, the method by which X and Y satisfy the above formula is not particularly limited. In order to control Y (the storage modulus of the resin in the cured resin) within a specific range, it is necessary to add a rigid structure such as an aromatic ring to the components constituting the resin composition used to obtain the cured resin. This can be achieved by introducing a polyfunctional component having a plurality of reactive groups to increase the crosslinking density of the cured product. Moreover, it can also be realized by obtaining a cured resin product using the above-mentioned resin composition.
In order to control X (weight increase rate at 85°C and 85% RH) within a specific range, for example, by introducing highly hydrophobic structures such as aliphatic skeletons and aromatic rings into the constituent components. Examples include a method of controlling the weight increase rate. Although various factors can be considered for weight increase, it is important to control weight increase due to moisture absorption.
Moreover, it can also be realized by obtaining a cured resin product using the above-mentioned resin composition.
Note that the storage modulus may be measured by any conventionally known method, but specific examples include the method described in the Examples section below. Further, the weight increase rate of the cured resin product at 85° C. and 85% RH is measured by the method described in the Examples section below.

[Manufacture of resin composition and cured resin product]
The method for producing the resin composition of the present invention and the cured resin product of the present invention will be explained by exemplifying the method for producing a sheet-like cured resin product made of the resin composition of the present invention.

A sheet-shaped cured resin product can be produced by a commonly used method. For example, it can be obtained by preparing the resin composition of the present invention, then molding the resin composition into a sheet shape and curing it.

The resin composition of the present invention can be obtained by uniformly mixing the inorganic coagulated filler, the resin, and other components added as necessary by stirring or kneading. For mixing, common kneading devices such as mixers, kneaders, single-screw or twin-screw kneaders, etc. can be used. During mixing, heating may be performed if necessary.

The mixing order of each component may be arbitrary as long as there is no particular problem such as reaction or precipitation, and examples include the following method.
A resin liquid is created by mixing and dissolving the resin in an organic solvent (for example, methyl ethyl ketone), and a sufficiently mixed inorganic coagulated filler and other components are added to the resulting resin liquid, and then the viscosity is adjusted. After further adding and mixing an organic solvent for use, additives such as a curing agent, a curing accelerator, or a dispersant are further added and mixed.

A commonly used method can be used to mold the prepared resin composition into a sheet.
For example, when the resin composition has plasticity or fluidity, the resin composition can be molded into a desired shape, for example, by curing the resin composition while being accommodated in a mold. In this case, injection molding, injection compression molding, extrusion molding, compression molding, and vacuum compression molding can be used.
The solvent in the resin composition can be removed by a known heating method such as a hot plate, hot air oven, IR heating furnace, vacuum dryer, or high frequency heater.

Further, a sheet-like cured resin product can also be obtained by cutting out a cured product of the resin composition into a desired shape.

A sheet-like cured resin product can also be obtained by forming a slurry-like resin composition into a sheet form by a method such as a doctor blade method, a solvent casting method, or an extrusion film forming method.

An example of a method for producing a sheet-like cured product using this slurry-like resin composition will be described below.

<Coating process>
First, a slurry-like resin composition is applied to the surface of a base material to form a coating film (sheet-like resin composition).

That is, a coating film is formed on a substrate using a slurry-like resin composition by a dipping method, a spin coating method, a spray coating method, a blade method, or any other method. A coating device such as a spin coater, slit coater, die coater, blade coater, etc. can be used to coat the slurry-like resin composition. With such a coating device, it is possible to uniformly form a coating film of a predetermined thickness on a substrate.

Note that as the base material, a copper plate or copper foil or a PET film, which will be described later, is generally used, but the base material is not limited in any way.

<Drying process>
The coating film formed by applying the slurry-like resin composition is heated to usually 10 to 150°C, preferably 25 to 120°C, more preferably 30 to 110°C, in order to remove the solvent and low molecular components. Dry at temperature.
By setting the drying temperature at or below the above upper limit, curing of the resin in the slurry-like resin composition is suppressed, and the resin in the sheet-like resin composition flows in the subsequent pressurizing process to remove voids. It tends to become easier. When the drying temperature is equal to or higher than the above lower limit, the solvent can be effectively removed and productivity tends to improve.

The drying time is not particularly limited, and can be adjusted as appropriate depending on the state of the slurry-like resin composition, the drying environment, and the like. The drying time is preferably 1 minute or more, more preferably 2 minutes or more, even more preferably 5 minutes or more, even more preferably 10 minutes or more, particularly preferably 20 minutes or more. The drying time is preferably 24 hours or less, more preferably 10 hours or less, even more preferably 4 hours or less, particularly preferably 2 hours or less.
When the drying time is at least the above lower limit, the solvent can be sufficiently removed, and the residual solvent tends to be prevented from forming voids in the cured resin material. When the drying time is equal to or less than the above upper limit, productivity tends to improve and manufacturing costs can be suppressed.

<Pressure process>
After the drying process, the obtained sheet-like material is It is desirable to subject the resin composition to a pressurizing process.

The pressurizing step is preferably carried out by applying a load of 2 MPa or more to the sheet-like resin composition on the base material. The load is preferably 5 MPa or more, more preferably 7 MPa or more, and still more preferably 9 MPa or more. Further, the load is preferably 1500 MPa or less, more preferably 1000 MPa or less, and still more preferably 800 MPa or less.
By controlling the load during pressurization to be less than or equal to the above upper limit value, the secondary particles of the agglomerated inorganic filler are not destroyed, and a sheet having high thermal conductivity without voids in the sheet-like cured resin product can be obtained. Can be done. By setting the load to the above lower limit value or more, the contact between the aggregated inorganic fillers becomes good and it becomes easier to form a heat conduction path, so it is possible to obtain a cured resin material having high heat conductivity.

The heating temperature of the sheet-like resin composition on the substrate in the pressurizing step is not particularly limited. The heating temperature is preferably 10°C or higher, more preferably 20°C or higher, even more preferably 30°C or higher. The heating temperature is preferably 300°C or lower, more preferably 250°C or lower, even more preferably 200°C or lower, even more preferably 100°C or lower, particularly preferably 90°C or lower.
By performing the pressurizing step in this temperature range, the melt viscosity of the resin in the sheet-like resin composition can be lowered, and voids and voids in the cured resin product can be further reduced. In addition, by heating at a temperature below the above upper limit, it tends to be possible to suppress the decomposition of organic components in the sheet-shaped resin composition and cured resin product, and to suppress voids generated by residual solvent.

The time for the pressurizing step is not particularly limited. The time of the pressurizing step is preferably 30 seconds or more, more preferably 1 minute or more, still more preferably 3 minutes or more, particularly preferably 5 minutes or more. The time of the pressurizing step is preferably 1 hour or less, more preferably 30 minutes or less, even more preferably 20 minutes or less.
When the pressurization time is equal to or less than the above upper limit value, the production time of the cured resin product can be suppressed, and production costs tend to be reduced. When the pressurization time is equal to or greater than the above lower limit, voids and voids in the cured resin material can be sufficiently removed, and heat transfer performance and voltage resistance characteristics tend to be improved.

<Curing process>
The curing step in which the resin composition of the present invention undergoes a complete curing reaction may be performed under pressure or without pressure, but when pressurized, for the same reason as above, It is desirable to perform this under the same conditions as the pressurizing step. Note that the pressurizing step and the curing step may be performed at the same time.
In particular, in the sheet-forming process that includes a pressing process and a curing process, it is preferable to perform the pressing and curing by applying a load within the above range.

The load when performing the pressurizing step and the curing step at the same time is not particularly limited. In this case, it is preferable to apply a load of 5 MPa or more to the sheet-shaped resin composition on the base material, more preferably 7 Pa or more, still more preferably 9 MPa or more, particularly preferably 20 MPa or more. It is. Further, the load is preferably 2000 MPa or less, more preferably 1500 MPa or less.
By keeping the load below the above upper limit when performing the pressurizing process and curing process simultaneously, the secondary particles of the agglomerated inorganic filler will not be destroyed, and high thermal conductivity will be achieved with no voids in the cured resin sheet. A sheet-like cured product having properties can be obtained. Moreover, by setting the load to the above lower limit value or more, the contact between the aggregated inorganic fillers becomes good and it becomes easier to form a heat conduction path, so it is possible to obtain a cured resin material having high heat conductivity.

When the pressing step and the curing step are performed simultaneously, the pressing time is not particularly limited. The pressurizing time is preferably 30 seconds or more, more preferably 1 minute or more, even more preferably 3 minutes or more, and particularly preferably 5 minutes or more. Moreover, the pressurization time is preferably 1 hour or less, more preferably 30 minutes or less, and still more preferably 20 minutes or less.
When the pressurization time is equal to or less than the above upper limit, the production time of a sheet-like cured resin product can be suppressed, and production costs tend to be reduced. When the pressurization time is equal to or longer than the above lower limit, voids and voids in the sheet-like cured resin material can be sufficiently removed, and heat transfer performance and voltage resistance characteristics tend to be improved.

The heating temperature of the sheet-like resin composition on the substrate in the case of performing the pressing step and the curing step at the same time is not particularly limited. The heating temperature is preferably 10°C or higher, more preferably 20°C or higher, even more preferably 30°C or higher. The heating temperature is preferably 300°C or lower, more preferably 250°C or lower, even more preferably 200°C or lower, even more preferably 100°C or lower, particularly preferably 90°C or lower.
By setting the heating temperature to the above lower limit or higher, the melt viscosity of the resin in the sheet-like resin composition can be lowered, and voids and voids in the cured resin can be eliminated. By setting the heating temperature to the above upper limit value or less, it tends to be possible to suppress the decomposition of organic components in the sheet-shaped resin composition and the sheet-shaped cured resin product, and to suppress voids generated by residual solvent.

The heating temperature of the sheet-like resin composition on the substrate when performing only the curing step is not particularly limited. The heating temperature is preferably 10°C or higher, more preferably 50°C or higher, still more preferably 100°C or higher. Further, the heating temperature is preferably 500°C or lower, more preferably 300°C or lower, even more preferably 200°C or lower, even more preferably 180°C or lower, particularly preferably 175°C or lower.
By setting the heating temperature within this temperature range, the curing reaction of the resin proceeds effectively. Heat deterioration of the resin is prevented by the heating temperature being below the above upper limit. When the heating temperature is equal to or higher than the above lower limit, the curing reaction of the resin proceeds more effectively.

The thickness of the sheet-like cured resin product thus formed is not particularly limited, but is preferably 50 μm or more, more preferably 80 μm or more, and still more preferably 100 μm or more. Further, the thickness of the cured resin product is preferably 400 μm or less, more preferably 300 μm or less.
When the thickness of the cured resin is equal to or greater than the above lower limit, voltage resistance characteristics are obtained and dielectric breakdown voltage tends to improve. When the thickness of the cured resin product is less than or equal to the above upper limit value, the device can be made smaller and thinner, and the thermal resistance of the resulting cured resin product (heat dissipation sheet) tends to be suppressed.

[Composite molded body]
The composite molded article of the present invention has a cured product part made of a cured product of the resin composition of the present invention and a metal part, and is usually formed by laminating and integrating these parts.

The metal portion may be provided on only one surface of the cured product portion made of the cured resin product of the present invention, or may be provided on two or more surfaces. For example, the sheet-shaped cured resin of the present invention may have metal parts only on one side, or may have metal parts on both sides. Moreover, the metal part may be patterned.

Such a composite molded article of the present invention can be produced by using the metal part as the base material and forming a sheet-like article made of the cured resin of the present invention on this base material according to the method described above. Can be done.
In addition, the composite molded article of the present invention is produced by peeling a sheet-like resin composition or cured resin product formed on a base material other than the metal part from the base material, and then heat-pressing it onto the metal member that will become the metal part. It can also be manufactured by

In this case, the sheet-like composition of the present invention is prepared in the same manner as above except that the slurry-like resin composition of the present invention is applied onto a base material such as PET (polyethylene terephthalate), which may be treated with a release agent. After forming the resin composition or cured resin, it is peeled off from the base material, and this sheet-like resin composition or cured resin is placed on another metal plate or sandwiched between two metal plates. In this state, they may be integrated by applying pressure.

As the metal plate, a metal plate having a thickness of about 10 μm to 10 cm and made of copper, aluminum, nickel-plated metal, etc. can be used.
The surface of the metal plate may be physically roughened or chemically treated with a surface treatment agent or the like. From the viewpoint of adhesion between the resin composition and the metal plate, it is more preferable that these treatments are carried out.

[Semiconductor device]
The composite molded article of the present invention can be used as a semiconductor device. In particular, it can be suitably used in power semiconductor devices that can achieve high output and high density by operating at high temperatures.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.
The values of various conditions and evaluation results in the following examples indicate the preferred range of the present invention, as well as the preferred range of the embodiments of the present invention, and the preferred range of the present invention is the preferred range of the embodiments described above. It can be determined by taking into consideration the range and the range shown by the values of the following examples or the combination of values of the examples.

[raw materials]
The raw materials used in the examples and comparative examples are as follows.

<Resin component>
Resin component 1: Structure (2) (R ³ = structure (4)) and structure (3) (R ⁴ , R ⁵ , R ⁶ , R ⁷ = methyl group)
Weight average molecular weight in terms of polystyrene: 30,000
Epoxy equivalent: 9,000 g/equivalent Resin component 2: Structure (1) (R ¹ = methyl group, R ² = phenyl group) and structure (3) (R ⁴ , R ⁵ , R ⁶ , R ⁷ = methyl group)
Weight average molecular weight in terms of polystyrene: 39,000
Epoxy equivalent: 13,000 g/equivalent Resin component 3: Manufactured by Mitsubishi Chemical Bisphenol F type solid epoxy resin containing a structure with two epoxy groups per molecule
Weight average molecular weight in terms of polystyrene: 60,000
Resin component 4: Bisphenol A liquid epoxy resin containing a structure with two epoxy groups per molecule, manufactured by Mitsubishi Chemical Corporation
Molecular weight: about 370
Resin component 5: Manufactured by Nagase ChemteX Co., Ltd. Multifunctional epoxy resin containing a structure having 4 or more glycidyl groups per molecule
Molecular weight: about 400
Resin component 6: Manufactured by Mitsubishi Chemical Hydrogenated bisphenol A type liquid epoxy resin containing a structure with two epoxy groups per molecule
Molecular weight: about 410
Resin component 7: Mitsubishi Chemical Corporation p-aminophenol type liquid multifunctional epoxy resin containing a structure having three or more epoxy groups per molecule
Molecular weight: approx. 290
Resin component 8: Manufactured by Mitsubishi Chemical Corporation Aliphatic skeleton liquid epoxy resin containing a structure with two epoxy groups per molecule
Molecular weight: about 900

<Inorganic filler>
Inorganic filler 1: Boron nitride aggregate particles having a house of cards structure, manufactured according to the method for producing boron nitride aggregate particles disclosed in the Examples of International Publication No. 2015/561028.
New Mohs hardness: 2
Volume average particle diameter: 45μm
Inorganic filler 2: Admatex, spherical alumina particles
New Mohs hardness: 9
Volume average particle diameter: 6.5μm
Thermal conductivity: 20-30W/m・K

<Curing agent>
Curing agent 1: “MEH-8000H” manufactured by Meiwa Kasei Co., Ltd.
Phenolic resin curing agent

<Curing catalyst>
Curing catalyst 1: "2E4MZ-A" manufactured by Shikoku Kasei Co., Ltd.
2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(17')]-ethyl-s-triazine
(Compound having a triazine ring as a nitrogen atom-containing heterocyclic structure)
Molecular weight: 247

[Sample preparation, measurement and evaluation]
The methods for producing molded bodies, measurement conditions, and evaluation methods in Examples and Comparative Examples are as follows.

<Example 1>
A mixture was prepared using a rotation-revolution stirring device so that the solid content contained 1:51% by weight of inorganic filler, 2:20% by weight of inorganic filler, and 29% by weight of components other than the inorganic filler. At this time, the content of components other than the inorganic filler in the solid content was adjusted so that the weight ratio was as described in the column of Example 1 in Table 1. Further, when preparing the above mixture, equal amounts of methyl ethyl ketone and cyclohexanone were used so that the above mixture accounted for 63% by weight (solid content concentration) of the coating slurry.

The resulting slurry-like resin composition (slurry for sheets) was applied to a PET base material using a doctor blade method, heated and dried at 60°C for 120 minutes, and then pressed at 42°C and 147 MPa for 10 minutes. A sheet-like resin composition with a thickness of 150 μm was obtained. The total content of methyl ethyl ketone and cyclohexanone in the sheet-like resin composition was 1% by weight or less.

Next, the sheet-like resin composition was sandwiched between one copper plate each having a thickness of 500 μm and 2,000 μm, the surfaces of which had been roughened 100 times with a #120 file in advance, and heated at 120° C. and 9.8 MPa for 30 minutes. Pressing was performed for 30 minutes, then the temperature was raised, and pressing was performed at 175° C. and 9.8 MPa for 30 minutes.

The composite molded body containing the copper plate and cured resin obtained above was etched by a predetermined method to pattern a copper plate with a thickness of 500 μm. The pattern was such that two circular patterns with a diameter of 25 mm remained.

<Examples 2-3, Comparative Examples 1-4>
Based on the method of Example 1, a mixture was prepared such that the solid content was 1:51% by weight of inorganic filler, 2:20% by weight of inorganic filler, and 29% by weight of components other than the inorganic filler. At this time, the sheet-shaped resin composition, the copper plate and the resin were prepared in the same manner as in Example 1, except that the weight ratio of the components other than the inorganic filler in the solid content was as shown in Table 1. A composite molded body containing a cured product was obtained.

<Initial breakdown voltage (BDV)>
The composite molded body containing the copper plate and cured resin prepared in Examples and Comparative Examples was immersed in Fluorinert FC-40 (manufactured by 3M), and tested using an ultra-high voltage withstand tester 7470 (manufactured by Keizoku Gijutsu Kenkyusho). An electrode was placed on the patterned copper having a diameter of 25 mm, a voltage of 0.5 kV was applied, and the voltage was increased by 0.5 kV every 60 seconds, and measurement was performed until dielectric breakdown occurred. When the BDV was 5 kV or more, it was written as "〇", and when it was less than 5 kV, it was written as "x".

<Peeling after repeated reflow test>
Among the composite molded bodies containing copper plates and cured resin products prepared in Examples and Comparative Examples, those whose initial breakdown voltage was evaluated as "○" were heated from room temperature to 290°C for 12 minutes in a nitrogen atmosphere. The temperature was raised at 290° C., maintained at 290° C. for 10 minutes, and then cooled to room temperature (reflow test). Thereafter, the interface between the copper plate and the cured resin sheet was observed using an ultrasonic imaging device FinSAT (FS300III) (manufactured by Hitachi Power Solutions). The measurement was carried out using a probe with a frequency of 50 MHz, a gain of 30 dB, and a pitch of 0.2 mm, with the sample placed in water.
Reflow tests and interfacial peeling observations were repeated until peeling occurred at the interface.
A case where interfacial peeling did not occur even after repeating the reflow test twice or more was written as "○", and a case where interfacial peeling occurred after the reflow test was repeated less than twice was written as "x".

<Weight increase rate of cured resin>
The sheet-like cured resin products prepared in Examples and Comparative Examples were cut into test pieces of 6 cm x 7 cm, dried at 150° C. for 1 hour, and the weight a was measured. Furthermore, these sheet-shaped cured resin products were stored for a certain period of time in an environment of 85°C and 85% RH using a constant temperature and humidity machine SH-221 (manufactured by ESPEC), and the weight was measured over time. It was stored until it reached constant weight) b. The weight increase rate was calculated using the following formula.
Weight increase rate (%) = (ba)/a × 100

<Storage modulus of resin composition>
Except for not using an inorganic filler, a resin composition was prepared using an autorotation-revolution stirring device in the same manner as in each example and comparative example, and after drying by heating, a rheometer "MCR302" manufactured by Anton Paar was used. The uncured resin composition was heated and cured using the following method, and the storage modulus at 200°C was measured.
An aluminum parallel plate was used for the measurement, and the measurement conditions were a strain of 0.3%, a frequency of 1 Hz, and a gap of 0.5 mm.
The temperature profile during heat curing starts at 25°C, increases the temperature to 120°C at 14°C per minute, holds for 30 minutes after reaching 120°C, then increases the temperature to 175°C at 7°C per minute, and then 175°C. After reaching 200°C, the temperature was held for 30 minutes, and the temperature was further increased to 200°C at 7°C per minute, and after reaching 200°C, it was held for 10 minutes. The storage elastic modulus measured when the sample was held at 200° C. for 10 minutes was used for evaluation.

From the measurement results of the weight increase rate and storage modulus, those that satisfy the above formula (I) are marked as "○", and those that do not meet are marked as "x".

The above measurement and evaluation results are shown in Table 1.

Table 1 shows that the cured resin of the present invention has excellent repeated reflow resistance.
That is, even if the weight increase rate is somewhat large, the storage elastic modulus is correspondingly large, so that a material that satisfies the formula (I) has excellent repeated reflow resistance. On the other hand, even if the weight increase rate is small, unless formula (I) is satisfied, the repeated reflow resistance is poor.

Claims (14)

A resin composition comprising an epoxy resin having three or more epoxy groups per molecule, an epoxy resin having a biphenyl structure and a weight average molecular weight of 10,000 or more, and an agglomerated inorganic filler, the resin composition comprising: When the weight increase rate at 85 ° C. and 85% RH after curing is X (weight %), and the storage elastic modulus at 200 ° C. of the cured product of the resin composition excluding inorganic filler is Y (Pa), the following A resin composition satisfying formula (I).
Y>2.01×10 ⁷ X+1.3×10 ⁶ (I) The epoxy resin having a biphenyl structure and a weight average molecular weight of 10,000 or more further has at least one structure selected from a structure represented by the following structural formula (1) and a structure represented by the following structural formula (2). The resin composition according to claim 1 , which has the following.

(In formula (1), R ¹ and R ² each represent an organic group, and in formula (2), R ³ represents a divalent cyclic organic group.) The content of the epoxy resin having a biphenyl structure and a weight average molecular weight of 10,000 or more is 1% by weight or more and 50% by weight or less based on 100% by weight of the solid content in the resin composition excluding inorganic fillers. , the resin composition according to claim 1 or 2 . Claim 1 , wherein the content of the epoxy resin having three or more epoxy groups per molecule is 10% by weight or more and 50% by weight or less based on 100% by weight of solid content in the resin composition excluding inorganic fillers. - The resin composition according to any one of 3 . The resin composition according to any one of claims 1 to 4 , wherein the epoxy resin having three or more epoxy groups per molecule has a molecular weight of 800 or less. The resin composition according to any one of claims 1 to 5, further comprising a bisphenol A liquid epoxy resin having a structure having two epoxy groups per molecule. The resin composition according to any one of claims 1 to 6 , further comprising a compound having a nitrogen atom-containing heterocyclic structure. The resin composition according to any one of claims 1 to 7 , wherein the agglomerated inorganic filler is boron nitride agglomerated particles. The resin composition according to claim 8 , wherein the boron nitride agglomerated particles have a house of cards structure. A composite molded article comprising a cured product part made of a cured product of the resin composition according to any one of claims 1 to 9, and a metal part. A semiconductor device comprising the composite molded body according to claim 10. A cured resin product using a resin composition comprising an epoxy resin having three or more epoxy groups per molecule, an epoxy resin having a biphenyl structure and a weight average molecular weight of 10,000 or more, and an agglomerated inorganic filler. , where the weight increase rate at 85°C and 85% RH of the cured resin is X (weight%), and the storage modulus at 200°C after curing of the resin composition excluding inorganic fillers is Y (Pa). A cured resin material satisfying the following formula (I).
Y>2.01×10 ⁷ X+1.3×10 ⁶ (I) The epoxy resin having a biphenyl structure and a weight average molecular weight of 10,000 or more further has at least one structure selected from a structure represented by the following structural formula (1) and a structure represented by the following structural formula (2). The cured resin product according to claim 12, which has the following.

(In formula (1), R ¹ and R ² each represent an organic group, and in formula (2), R ³ represents a divalent cyclic organic group.) The cured resin product according to claim 12 or 13, wherein the resin composition further includes a bisphenol A liquid epoxy resin having a structure having two epoxy groups per molecule.