JP2008189815A - Dispersant, filler, heat-conductive resin composition and heat-conductive sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dispersant effective for improving a coefficient of thermal conductivity of a cured heat-conductive resin composition in which a filler using an inorganic nitride is dispersed into a resin component using an epoxy resin. <P>SOLUTION: The dispersant having a predetermined molecular structure is used in order to improve dispersibility of the filler in a heat-conductive resin composition in which a filler using an inorganic nitride is dispersed into a resin component using an epoxy resin. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a dispersant used to improve the dispersibility of the filler in a thermally conductive resin composition in which a filler in which an inorganic nitride is used is dispersed in a resin component in which an epoxy resin is used.
Moreover, this invention relates to the filler used for the heat conductive resin composition containing the resin component in which the epoxy resin was used, and the filler in which the inorganic nitride was used.
The present invention also relates to a thermally conductive resin composition in which a filler in which an inorganic nitride is used is dispersed in a resin component in which an epoxy resin is used.
Furthermore, this invention relates to the heat conductive sheet formed by heat-curing the heat conductive resin composition and shape | molding in a sheet form.

Conventionally, by adding a filler to a resin composition, it has been performed to improve the strength or to improve thermal conductivity as compared with a single resin as a base.
In particular, a thermally conductive resin composition in which an inorganic filler for improving thermal conductivity is dispersed in a thermosetting base resin such as an epoxy resin is used for sealing a chip component or a circuit in which a heat generating component is mounted. Widely used in electronic component applications such as the formation of an insulating layer between a heat sink and a heat sink.
For example, in Patent Document 1, a highly thermally conductive resin layer formed into a sheet shape from a thermally conductive resin composition containing a base resin and a filler is laminated on a metal foil layer formed using a metal foil. The high heat conductive adhesive sheet with metal foil is described, and it is described that this high heat conductive adhesive sheet with metal foil is used for bonding semiconductor chips.

Since this thermal conductive resin composition is usually required to have excellent thermal conductivity and heat resistance, the filler contained in the thermal conductive resin composition includes high thermal conductivity such as boron nitride and aluminum nitride. Inorganic nitrides having a ratio are dispersed in a thermosetting resin such as an epoxy resin, and fillers in which these inorganic nitrides are used in such a thermally conductive resin composition (hereinafter referred to as “nitride fillers”). ”) Is also being studied for high filling.
For example, in Patent Document 2, the thermal conductivity of a cured product can be set to 3 to 10 W / mK by using a thermally conductive resin composition in which an epoxy resin is highly filled with 80 to 95% by weight of an epoxy resin. It is described.

However, fillers using nitrides such as boron nitride are usually more difficult to disperse in the resin component than fillers such as silicon oxide and aluminum oxide.
Therefore, even if the filler made of inorganic nitride is highly filled in the heat conductive resin composition, there is a possibility that the filler is not sufficiently dispersed and aggregation tends to occur.
In this way, when the filler agglomerates, good heat transfer is difficult to be performed.For example, even if the filler is highly filled, the effect of improving the thermal conductivity commensurate with the amount of filler filled in the cured product of the thermally conductive resin composition It becomes difficult to exhibit.

On the other hand, Patent Document 2 describes the use of additives such as a dispersant and a coupling agent.
Further, in Patent Document 3, a filler using boron nitride (hereinafter also referred to as “boron nitride filler”) is treated with an isocyanate compound, and interaction between fillers due to amines, hydroxyl groups, and the like existing at the filler edge is caused. Further, Patent Document 4 describes a thermosetting heat conductive resin composition containing a nonionic surfactant.
The thermal conductive resin compositions described in these patent documents are expected to have a filler dispersibility improvement effect to some extent, but in any case, it is difficult to expect a sufficient improvement effect. Even if it fills, it becomes difficult to make the hardened | cured material of a heat conductive resin composition exhibit the heat conductivity improvement effect commensurate with the filling amount of a filler.

  That is, in a heat conductive resin composition in which a filler in which an inorganic nitride is used is dispersed in a resin component in which an epoxy resin is used, it is conventionally difficult to sufficiently improve the heat conductivity of a cured product. Has the problem.

JP-A-11-186473 JP 2001-348488 A JP 2001-192500 A Japanese Patent Laid-Open No. 10-60161

This invention is made | formed in view of the said problem, and the heat conductivity of the hardened | cured material of the heat conductive resin composition by which the filler in which the inorganic nitride was used for the resin component in which the epoxy resin was used is disperse | distributed. The first challenge is to provide a dispersant that is effective in improving the quality.
The present invention also provides the filler effective for improving the thermal conductivity of a cured product of a thermally conductive resin composition containing a resin component using an epoxy resin and a filler using an inorganic nitride. This is a second issue.
In addition, the present invention provides a thermally conductive resin composition in which a filler in which an inorganic nitride is used is dispersed in a resin component in which an epoxy resin is used, and the cured product can have excellent thermal conductivity. There are three issues.
Furthermore, a fourth object of the present invention is to provide a thermally conductive sheet that is formed by heat curing a thermally conductive resin composition containing a filler and is excellent in thermal conductivity.

  In the case where the filler using the inorganic nitride is dispersed in the resin component using the epoxy resin, the present inventors make the dispersibility of the filler into a conventional dispersant by using a dispersant having a predetermined structure. As a result, the present invention has been completed.

  That is, in order to solve the first problem, the present invention provides a dispersion of the filler in a thermally conductive resin composition in which a filler in which an inorganic nitride is used is dispersed in a resin component in which an epoxy resin is used. The dispersant used to improve the property, the dispersant is represented by the following general formula (1)

(In the formula, X is a C1-5 linear or branched alkyl group or a hydrogen atom, and Y is a C1-5 linear or branched alkyl group. R ¹¹ , R ¹² Is a hydrogen atom or a substituent, and R ¹¹ and R ¹² may be the same or different, m represents an integer of 1 to 10, and n represents an integer of 5 to 20. )
And the following general formula (2)

(In the formula, R ²¹ and R ²⁴ are isocyanate groups or organic monoisocyanate residues, and R ²¹ and R ²⁴ may be the same or different. A ²¹ and A ²² are organic diisocyanates. a residue, a ^21, a ²² is optionally be the same or different .Z ²¹ is a urethane bond having a nitrogen atom bonded to a ^21, a urea bond, an amide bond, Z ²² is , Represents a urethane bond having a nitrogen atom bonded to A ²² , a urea bond or an amide bond, R ²² and R ²³ are a polyether residue or a polyalkylene carbonate diol residue; ²² and R ²³ may be the same or different.)
The dispersing agent is characterized by containing at least one of the compounds represented by formula (1).

Moreover, in order to solve said 2nd subject, this invention provides the filler surface-treated with this dispersing agent.
In order to solve the third problem, the present invention provides a thermally conductive resin composition containing the dispersant.
Furthermore, in order to solve the fourth problem, the present invention provides a heat conductive sheet formed by heat-curing the heat conductive resin composition into a sheet shape.

According to the present invention, the dispersant contains at least one of the compound represented by the general formula (1) and the compound represented by the general formula (2).
Since the compound represented by the general formula (1) has a portion having a secondary amine having high affinity for inorganic nitride and a polyalkylene oxide portion having high affinity for epoxy resin, an epoxy resin was used. The dispersibility of the filler in the thermally conductive resin composition in which a filler using an inorganic nitride as the resin component is dispersed can be sufficiently improved.
Therefore, the filler can be highly filled while suppressing the aggregation of the filler in the thermally conductive resin composition.
And since this secondary amine raise | generates a crosslinking reaction with an epoxy group at the time of thermosetting of an epoxy resin, the thermal resistance of the interface of the said filler and resin component in hardened | cured material can be reduced.
That is, by using the dispersant, the thermal conductivity of the cured product of the thermally conductive resin composition can be improved as compared with the conventional one.

In addition, the compound represented by the general formula (2) has a portion having a carbodiimide having a high affinity for the inorganic nitride and a polyether structure or a polyalkylene carbonate diol structure having a high affinity for the epoxy resin. It is possible to sufficiently improve the dispersibility of the filler in the heat conductive resin composition in which a filler in which an inorganic nitride is used is dispersed in a resin component in which a resin is used.
Therefore, the filler can be highly filled while suppressing the aggregation of the filler in the thermally conductive resin composition.
And since this carbodiimide raise | generates a crosslinking reaction with an epoxy group at the time of thermosetting of an epoxy resin, the thermal resistance of the interface of the said filler and resin component in hardened | cured material can be reduced.
That is, by using the dispersant, the thermal conductivity of the cured product of the thermally conductive resin composition can be improved as compared with the conventional one.

Moreover, since the filler surface-treated with the dispersant exhibits excellent dispersibility with respect to the resin component in which the epoxy resin is used, it can be highly filled in the heat conductive resin composition.
In addition, the filler surface-treated with the dispersant reduces the thermal resistance at the interface with the resin component because the dispersant and the epoxy resin are crosslinked when the thermally conductive resin composition is thermoset. obtain.
That is, the filler which can improve the heat conductivity of the hardened | cured material of a heat conductive resin composition compared with a conventional one can be provided.
Also, by containing the dispersant, the filler in the thermally conductive resin composition in which the filler in which the inorganic nitride is used is dispersed in the resin component in which the epoxy resin is used is excellent. Can be.
Therefore, the heat conductivity of the cured product can be improved as compared with the conventional heat conductive resin composition.
Furthermore, the heat conductive sheet formed by heat-curing the thermosetting resin composition containing the dispersant to form a sheet has excellent heat conductivity.

Hereinafter, with respect to a preferred embodiment of the present invention, a case where the heat conductive resin composition is used for forming a heat conductive sheet with metal foil (hereinafter also referred to as “high heat conductive adhesive sheet with metal foil”) is taken as an example. explain.
First, a highly heat-conductive adhesive sheet with metal foil will be described with reference to FIG.

  The high heat conductive adhesive sheet with metal foil is formed by laminating a high heat conductive resin layer formed in a sheet shape with a heat conductive resin composition on a metal foil layer formed using a metal foil. In FIG. 1, the high thermal conductive resin layer is bonded to a heat sink of a semiconductor module.

  The thermally conductive resin composition used for the formation of the high thermal conductive resin layer has a resin component using an epoxy resin, a filler using an inorganic nitride, and a dispersibility of the filler in the resin component. A dispersant for improvement is contained.

The epoxy resin used for the resin component is not particularly limited, and examples thereof include a cresol novolac type, a dicyclopentadiene type, a biphenyl type, a bisphenol type, and a trifunctional naphthalene type.
Especially, as an epoxy resin, a normal temperature thing is preferable. This room temperature solid epoxy is preferable when the room temperature liquid epoxy resin is used, so that the high thermal conductive resin layer side is coated under heating conditions so as to adhere the high thermal conductive adhesive sheet with metal foil to the adherend. This is because when the epoxy resin is brought into contact with the adherend, the viscosity of the epoxy resin is too low and the epoxy resin may ooze out from the edge of the high thermal conductive adhesive sheet with metal foil.
When the oozing of the epoxy resin is severe, there is a possibility that the epoxy resin film is formed at a place where the metal part should be exposed, such as the back side of the metal foil layer.

On the other hand, if the viscosity does not decrease to some extent when adhering to the adherend, there is a tendency for voids to form between the adherend and the high thermal conductive resin layer side, and the thermal conductivity from the adherend side to the metal foil layer side. May also be reduced.
As the epoxy resin, in which a moderate flowability is imparted to the resin composition and these problems can be more reliably suppressed, a normal temperature solid bisphenol A type epoxy resin having an epoxy equivalent of 450 to 2000 g / eq, A novolac type epoxy resin having a softening point between 87 ° C. and 93 ° C. with a polyfunctional normal temperature solid having an epoxy equivalent of 160 to 220 g / eq (bisphenol A type epoxy resin / novolak type epoxy resin) = 40/60 to 60 It is preferable to use one that is mixed at a weight ratio of / 40.
In addition, this epoxy equivalent can be calculated | required by JISK7236.

  Moreover, in order to modify the resin composition in which this epoxy resin is used, the phenol resin, the acrylic resin, the polyamide resin, etc. other than the epoxy resin are used for the heat conductive resin composition used for forming the high thermal conductive resin layer. This resin can be added within a range not impairing the effects of the present invention.

  The filler is not particularly limited as long as inorganic nitride is used, but any inorganic nitride of boron nitride, aluminum nitride, silicon nitride, or gallium nitride is used. It is particularly preferable that boron nitride is used.

When boron nitride is used as the filler (hereinafter also referred to as “boron nitride filler”), those having an average particle diameter of 1 to 20 μm having a scale shape can be usually used. This average particle diameter can be determined by measuring the D50 value by laser diffraction.
In addition to the filler using this nitride, the filler using aluminum oxide, silicon carbide, silicon dioxide, diamond, etc. is used for the thermally conductive resin composition used for forming the high thermal conductive resin layer. Can be used in combination as long as the effects of the present invention are not impaired.

  The dispersant includes the following general formula (1)

(In the formula, X is a C1-5 linear or branched alkyl group or a hydrogen atom, and Y is a C1-5 linear or branched alkyl group. R ¹¹ , R ¹² Is a hydrogen atom or a substituent, and R ¹¹ and R ¹² may be the same or different, m represents an integer of 1 to 10, and n represents an integer of 5 to 20. And a compound represented by the following general formula (2)

(In the formula, R ²¹ and R ²⁴ are isocyanate groups or organic monoisocyanate residues, and R ²¹ and R ²⁴ may be the same or different. A ²¹ and A ²² are organic diisocyanates. a residue, a ^21, a ²² is optionally be the same or different .Z ²¹ is a urethane bond having a nitrogen atom bonded to a ^21, a urea bond, an amide bond, Z ²² is , Represents a urethane bond having a nitrogen atom bonded to A ²² , a urea bond or an amide bond, R ²² and R ²³ are a polyether residue or a polyalkylene carbonate diol residue; ²² and R ²³ may be the same or different.) A compound containing at least one of them is used.

  Although it does not specifically limit as a dispersing agent containing the compound represented by the said General formula (1), For example, from Dai-ichi Kogyo Seiyaku Co., Ltd. as a brand name "Discall 202", "Discall 206" etc. A commercially available thing can be illustrated as a commercially available thing.

The dispersing agent containing a compound represented by the general formula (2), is not particularly limited, A ^21, A ²² in the formula is a diphenyl methane diisocyanate residue and tolylene diisocyanate residues aromatic Those having a group polycarbodiimide component are preferred.
Further, R ²² and R ²³ in the formula are preferably a polytetramethylene glycol residue or a carbodinate diol residue.
That is, as a dispersant containing a compound represented by the general formula (2), an aromatic polycarbodiimide component in which A ²¹ and A ²² in the formula are diphenylmethane diisocyanate residues and tolylene diisocyanate residues, and polytetra It is particularly preferable to use a compound having a structure in which an alcohol component such as methylene glycol or carbodinate diol is bonded by a urethane bond or an amide bond.

The content of the dispersant in the heat conductive resin composition in the present embodiment is usually such that the compound represented by the general formula (1) or the general formula (2) is added to 100 parts by mass of the nitride filler. On the other hand, the ratio is usually 0.1 to 5.0 parts by mass.
The content of the dispersant is usually in the above range with respect to the nitride filler. If the content is less than the above range, the dispersibility of the nitride filler may not be sufficiently improved, If the dispersant is used in an amount exceeding the above range, the thermal conductivity of the cured product of the heat conductive resin composition may be lowered, or the electrical insulation may be lowered.
In such a point, the content of the dispersant is such that the compound represented by the general formula (1) or the general formula (2) is 0.5 to 3 with respect to 100 parts by mass of the nitride filler. It is preferable to be 0.0 parts by mass.

The method for incorporating the dispersant into the heat conductive resin composition is not particularly limited. For example, a method of incorporating the dispersant into the resin component before dispersing the nitride filler into the resin component, or nitriding into the resin component For example, a method of treating the surface of the nitride filler with this dispersant in advance before dispersing the filler can be employed.
A method for pre-treating the nitride filler with a dispersant in advance is not particularly limited. For example, the nitride filler is immersed in a solution obtained by diluting the dispersant with a solvent, or a solution is added to the nitride filler. The method of drying after spraying can be employed.
Thus, the nitride filler surface-treated in advance with the dispersant more reliably adheres to the surface, and the dispersibility with respect to the resin is further improved.

  Although not described in detail here, the thermally conductive resin composition of the present embodiment includes a curing agent, an accelerator, an anti-aging agent, an oxidation agent in addition to the resin component, nitride filler, dispersant, and the like as described above. Various compounding agents generally used in a resin composition such as an inhibitor, a stabilizer, an antifoaming agent, a flame retardant, a thickener, and a pigment can be appropriately added within a range not impairing the effects of the present invention.

Such a heat conductive resin composition is formed into a sheet shape on a metal foil layer, and can be used as a high heat conductive adhesive sheet with metal foil. The thickness of the metal foil layer is usually 50 to 300 μm. The metal foil can be used.
Examples of the metal foil include those using pure metals and alloys such as copper, aluminum, nickel, and iron. Further, various types of plated or a plurality of types of metals are laminated. A clad foil or the like can also be used.

Moreover, it is preferable that the metal foil of this metal foil layer is surface-roughened on the interface side with the heat conductive resin composition in order to improve the adhesive force with the heat conductive resin composition.
This surface roughening can be performed by sandblasting or oxidizing the surface of the metal foil.
In the case of using an electrolytic metal foil, the mat surface (roughened surface) can be used as a laminated interface with the high thermal conductive resin layer, and no special treatment such as sandblasting or oxidation treatment is required. This is preferable in terms of points.

In addition, as electrolytic metal foil used for formation of this metal foil layer, it is preferable to use electrolytic copper foil in the point which is comparatively cheap, is excellent also in corrosion resistance, and has high thermal conductivity.
Furthermore, it is preferable to use the electrolytic copper foil whose zinc surface has been subjected to a zincate treatment.

Usually, a minute unevenness of several μm is formed on the mat surface of this electrolytic metal foil, but in the thermally conductive resin composition of this embodiment, the dispersibility of the nitride filler is sufficiently improved. For this reason, the mat surface has excellent conformability with respect to the irregularities and can exhibit excellent adhesion to the metal foil.
Moreover, in the thermally conductive resin composition of the present embodiment, the dispersibility of the nitride filler is sufficiently improved, so that aggregation of the nitride filler is suppressed.
That is, this heat conductive resin composition can be highly filled with a nitride filler.
Thereby, it is possible to exhibit excellent thermal conductivity commensurate with the blending amount of the nitride filler with respect to a molded article using the thermally conductive resin composition.
Furthermore, since the aggregation of the nitride filler is suppressed, the heat transfer coefficient at the interface between the metal foil and the thermally conductive resin composition can be excellent, and thus the thermal resistance of the entire highly heat-conductive adhesive sheet with metal foil The value can be further reduced.

  In addition, by thermally curing the thermally conductive resin composition, the epoxy resin component and the dispersant are cross-linked, reducing the thermal resistance at the interface between the nitride filler and the resin component (improving the heat transfer rate). The thermal conductivity of the cured product after the heat effect can be improved as compared with the uncured molded product.

In addition, by containing the dispersant in the heat conductive resin composition, aggregation of the nitride filler can be suppressed and the affinity between the nitride filler and the resin interface can be improved. Mechanical properties such as strength of a molded product using the composition and electrical properties such as dielectric breakdown voltage can be improved.
Furthermore, by thermally curing the thermally conductive resin composition, the epoxy resin component and the dispersant are crosslinked, and the mechanical properties and electrical properties of the cured product obtained by thermally curing the thermally conductive resin composition are not yet achieved. This can be further improved as compared with a molded product in a cured state.
Therefore, it is also possible to reduce the thickness of the high thermal conductive resin layer in the high thermal conductive adhesive sheet with metal foil, and further reduce the thermal resistance of the high thermal conductive adhesive sheet with metal foil by thinning the high thermal conductive resin layer. Can be.

  The method for thermosetting the thermally conductive resin composition is not particularly limited, and a curing agent or a curing accelerator generally used for thermosetting epoxy resins is blended in the thermally conductive resin composition, and these curings are performed. For example, a method of heating the molded product after forming a heat conductive resin composition containing an agent and a curing accelerator into a desired shape such as a sheet can be employed.

The curing agent is not particularly limited, and examples thereof include amine curing agents such as diaminodiphenyl sulfone, dicyandiamide, diaminodiphenylmethane, and triethylenetetramine, phenol novolac resins, aralkyl type phenol resins, and dicyclopentadiene modified phenols. Resin, phenolic curing agents such as naphthalene type phenolic resin and bisphenolic phenolic resin, acid anhydrides and the like can be used.
The curing accelerator is not particularly limited, but an amine curing accelerator such as boron trifluoride monoethylamine is suitable.

In addition, as a method of forming a highly heat conductive adhesive sheet with a metal foil by forming a heat conductive resin composition on a metal foil layer in a sheet shape, a conventionally widely used method can be employed, for example, A coating method or the like can be employed.
In this case, the heat conductive resin composition can be appropriately diluted with a solvent to adjust the viscosity to be easily coated on the metal foil.

In the present embodiment, the dispersibility of the nitride filler is sufficiently improved, so that the nitride filler can be highly filled while suppressing the decrease in electrical insulation, and the heat conductive resin composition is insulated. The semiconductor module is characterized in that reliability (for example, a dielectric breakdown voltage of 10 kV / 0.2 mm or more) and high thermal conductivity (for example, 10 W / mK or more) can be imparted and the effects of the present invention can be exhibited more remarkably. Although the high heat conductive adhesive sheet with metal foil used by being adhered to a heat sink or the like has been described as an example, the present invention is not limited to the case where the dispersant of the present invention is used for the heat conductive resin composition for such use.
Therefore, for example, a conductive material can be contained in the thermally conductive resin composition.

  EXAMPLES Next, although an Example is given and this invention is demonstrated in more detail, this invention is not limited to these.

(Example 1)
(Preparation of base resin solution)
66 g of bisphenol type epoxy resin (product name “YD-011” manufactured by Toto Kasei Co., Ltd.), 66 g of cresol novolac resin (product name “YDCN704” manufactured by Toto Kasei Co., Ltd.), and 4,4′-diaminodiphenyl which is a curing agent A resin solution was prepared by mixing and dissolving 26 g of sulfone (trade name “Seika Cure S” manufactured by Wakayama Seika Co., Ltd.), 1.3 g of boron trifluoride monoethylamine as a curing accelerator, and 106 g of 2-butanone.
A base obtained by mixing 212.6 g of this resin solution with 3.0 g of a dispersant (trade name “DISCOL 202” manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) using the compound represented by the general formula (1). A resin solution was prepared.

(Dispersion of nitride filler: preparation of coating solution)
300 g of boron nitride filler (trade name “UHP-1” manufactured by Showa Denko KK) is placed in a “Hibis mixer” manufactured by Premix, and the base resin solution is added so that the boron nitride filler is 55% by volume and in a reduced pressure state. After stirring, the pressure was returned to normal pressure.
Next, 66 g of 2-butanone and 132 g of toluene were added and stirred again to prepare a coating liquid in which the thermally conductive resin composition was diluted with a solvent.

(Preparation of high heat conductive adhesive sheet with metal foil)
The obtained coating solution is applied onto copper foil and dried to produce a highly heat conductive adhesive sheet with metal foil in which a high heat conductive resin layer formed into a sheet shape with a heat conductive resin composition is laminated on the copper foil. did.
Furthermore, after performing hot pressing at 120 ° C. for 20 minutes while applying pressure at a pressure of 5.9 MPa using a hot press, the hot pressing at 180 ° C. for 2 hours is subsequently performed to provide a highly heat conductive adhesive sheet with metal foil. Curing was performed to prepare an evaluation sample.
The film pressure of the highly thermally conductive resin layer after curing was 0.2 mm.

(Example 2)
Instead of the trade name “DISCOL 202” manufactured by Daiichi Kogyo Seiyaku Co., Ltd., the trade name “DISCOL 206” made by Daiichi Kogyo Seiyaku Co., Ltd., which contains the compound represented by the general formula (1), Except having used, the high heat conductive adhesive sheet with metal foil was produced similarly to Example 1, and the evaluation sample was produced.

(Comparative Example 1)
A high heat conductive adhesive sheet with a metal foil was prepared in the same manner as in Example 1 except that no dispersant was added to the base resin solution, and an evaluation sample was prepared.
In addition, the coating liquid used for preparation of the evaluation sample of this comparative example 1 was solidified on the next day.

(Comparative Example 2)
In place of the trade name “DISCOL 202” manufactured by Daiichi Kogyo Seiyaku Co., Ltd., the dispersant includes both the compound represented by the general formula (1) and the compound represented by the general formula (2). A highly heat-conductive adhesive sheet with metal foil was prepared in the same manner as in Example 1 except that the phosphate ester type anionic surfactant (trade name “Plysurf A208F” manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was used, and an evaluation sample was prepared. did.

(Comparative Example 3)
In place of the trade name “DISCOL 202” manufactured by Daiichi Kogyo Seiyaku Co., Ltd., the dispersant includes both the compound represented by the general formula (1) and the compound represented by the general formula (2). A high thermal conductive adhesive sheet with a metal foil was prepared in the same manner as in Example 1 except that the polycarboxylic acid type polymer surfactant (trade name “Homogenol L-18” manufactured by Kao Corporation) was used, and an evaluation sample was prepared. .

(Example 3)
(Preparation of base resin solution)
66 g of bisphenol type epoxy resin (product name “YD-011” manufactured by Toto Kasei Co., Ltd.), 66 g of cresol novolac resin (product name “YDCN704” manufactured by Toto Kasei Co., Ltd.), and 4,4′-diaminodiphenyl which is a curing agent A base resin solution was prepared by mixing and dissolving 26 g of sulfone (trade name “Seika Cure S”, manufactured by Wakayama Seika Co., Ltd.), 1.3 g of boron trifluoride monoethylamine, which is a curing accelerator, and 106 g of 2-butanone. .

(Dispersion of nitride filler: preparation of coating solution)
Dispersant containing a compound represented by the general formula (2) (cyclohexanone solution of polycarbodiimide resin (concentration: 20% by mass)) on 300 g of boron nitride filler (trade name “UHP-1” manufactured by Showa Denko KK) 15 g of Optmate, trade name “HR-712”) was directly mixed and stirred under reduced pressure using a premix “Hibis mixer” to perform nitride filler surface treatment.
Next, the pressure was returned to normal pressure, and 212.6 g of the base resin solution was added so that the boron nitride filler was 55% by volume. After stirring again for 20 minutes under reduced pressure, the pressure was returned to normal pressure, 66 g of 2-butanone and 132 g of toluene. Was added and stirred to prepare a coating liquid in which the thermally conductive resin composition was diluted with a solvent.

(Preparation of high heat conductive adhesive sheet with metal foil)
The obtained coating solution is applied onto copper foil and dried to produce a highly heat conductive adhesive sheet with metal foil in which a high heat conductive resin layer formed into a sheet shape with a heat conductive resin composition is laminated on the copper foil. did.
Furthermore, after performing hot pressing at 120 ° C. for 20 minutes while applying pressure at a pressure of 5.9 MPa using a hot press, the hot pressing at 180 ° C. for 2 hours is subsequently performed to provide a highly heat conductive adhesive sheet with metal foil. Curing was performed to prepare an evaluation sample.
The film pressure of the highly thermally conductive resin layer after curing was 0.2 mm.

Example 4
Implemented except that the amount of dispersant (trade name “HR-712” manufactured by Optmate Co., Ltd.) used was changed to 45 g instead of 15 g, and the amount of 2-butanone added last was 36 g instead of 66 g. A high heat conductive adhesive sheet with a metal foil was prepared in the same manner as in Example 3, and an evaluation sample was prepared.

(Example 5)
A toluene solution of a resin obtained by polymerizing tolylene diisocyanate and 1-naphthalene monoisocyanate at a ratio (molar ratio) of 100: 15 in place of the trade name “HR-712” manufactured by Optmate Co., Ltd. (concentration: 40 mass) %) Was used, and a high heat conductive adhesive sheet with a metal foil was prepared in the same manner as in Example 3 to prepare an evaluation sample.

(Example 6)
Instead of 15 g of the trade name “HR-712” manufactured by Optmate Corporation, the dispersant is 3.0 g of trade name “Carbodilite V-05” manufactured by Nisshinbo Co., Ltd., and this dispersant is directly mixed with the boron nitride filler. Instead, a high thermal conductive adhesive sheet with a metal foil was prepared in the same manner as in Example 3 except that it was mixed on the base resin solution side, and an evaluation sample was prepared.

(Example 7)
The high thermal conductive adhesive sheet with metal foil was the same as in Example 3 except that the dispersant used was Optmate and trade name “HR-742” instead of Optmate and trade name “HR-712”. And an evaluation sample was prepared.

(Example 8)
A highly heat-conductive adhesive sheet with metal foil as in Example 6 except that Nisshinbo Co., Ltd., trade name “Carbodilite V-07” was used instead of Nisshinbo Co., Ltd., trade name “Carbodilite V-05”. And an evaluation sample was prepared.

(Comparative Example 4)
A high heat conductive adhesive sheet with a metal foil was prepared in the same manner as in Example 3 except that the dispersant was 3.0 g of a polycarboxylic acid type polymer surfactant (trade name “Homogenol L-18” manufactured by Kao Corporation). An evaluation sample was prepared.

(Comparative Example 5)
A high heat conductive adhesive sheet with a metal foil was prepared in the same manner as in Example 3 except that 3.0 g of the trade name “HITENOL LA-16” manufactured by Daiichi Kogyo Seiyaku Co., Ltd. was used, and an evaluation sample was prepared.

(Comparative Example 6)
A highly heat-conductive adhesive sheet with a metal foil was prepared in the same manner as in Example 3 except that the dispersant was 5.0 g made by Big Chemie and trade name “Disperbyk-164” (concentration 60 mass%: butyl acetate solution). Was made.

(Comparative Example 7)
A high heat conductive adhesive sheet with a metal foil was prepared in the same manner as in Example 3 except that no dispersant was added to the base resin solution, and an evaluation sample was prepared.
In addition, the coating liquid used for preparation of the evaluation sample of this comparative example 7 was solidified on the next day.

(Evaluation)
The thermal conductivity and the breakdown voltage were measured using the evaluation samples of each example and comparative example.
The thermal conductivity is obtained by the product name “ai-phase mobile” manufactured by Eye Phase Co., Ltd., and the heat capacity per unit volume of the thermal conductive sheet is determined by measurement using a differential scanning calorimeter (DSC). Measured and calculated by multiplying the previous thermal diffusivity.
The dielectric breakdown voltage was measured at a pressure increase rate of 1 kV / min in normal temperature insulating oil (Type 1 No. 2 insulating oil specified in JIS C 2320).
In addition, the brittleness of the cured thermally conductive resin composition is judged by finger touch, and “○” indicates that the handling is good and does not cause trouble during molding, but there is a feeling that it is somewhat brittle. Those that seemed to be normal level with no problem were judged as “△”, and those that were fragile and required careful handling at the time of molding were judged as “x”.
The results are shown in Tables 1 and 2.

  As can be seen from this table, since the predetermined dispersant is used in the thermally conductive resin composition of the present invention, it has an excellent dielectric breakdown voltage even when 55% by volume of boron nitride filler is contained. In addition, a cured product having excellent thermal conductivity can be formed.

Sectional drawing which shows the usage method of the high heat conductive adhesive sheet with metal foil.

Claims (6)

A dispersant used to improve the dispersibility of the filler in a thermally conductive resin composition in which a filler in which an inorganic nitride is used is dispersed in a resin component in which an epoxy resin is used,
The dispersant is represented by the following general formula (1)

(In the formula, X is a C1-5 linear or branched alkyl group or a hydrogen atom, and Y is a C1-5 linear or branched alkyl group. R ¹¹ , R ¹² Is a hydrogen atom or a substituent, and R ¹¹ and R ¹² may be the same or different, m represents an integer of 1 to 10, and n represents an integer of 5 to 20. )
And the following general formula (2)

(In the formula, R ²¹ and R ²⁴ are isocyanate groups or organic monoisocyanate residues, and R ²¹ and R ²⁴ may be the same or different. A ²¹ and A ²² are organic diisocyanates. a residue, a ^21, a ²² is optionally be the same or different .Z ²¹ is a urethane bond having a nitrogen atom bonded to a ^21, a urea bond, an amide bond, Z ²² is , Represents a urethane bond having a nitrogen atom bonded to A ²² , a urea bond or an amide bond, R ²² and R ²³ are a polyether residue or a polyalkylene carbonate diol residue; ²² and R ²³ may be the same or different.)
The dispersing agent characterized by containing at least one among the compounds represented by these.   The dispersant according to claim 1, wherein the inorganic nitride is any one of boron nitride, aluminum nitride, silicon nitride, and gallium nitride. The filler used in a thermally conductive resin composition comprising a resin component in which an epoxy resin is used and a filler in which an inorganic nitride is used,
A filler which is surface-treated with the dispersant according to claim 1.   The filler according to claim 3, wherein the inorganic nitride is any one of boron nitride, aluminum nitride, silicon nitride, and gallium nitride.   A heat conductive resin composition in which a filler in which an inorganic nitride is used is dispersed in a resin component in which an epoxy resin is used, wherein the dispersant according to claim 1 or 2 is contained. A thermally conductive resin composition.   A heat conductive sheet obtained by heat-curing the heat conductive resin composition according to claim 4 to form a sheet.

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