JP2000063628A - Semiconductor sealing epoxy resin composition and semiconductor device using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor sealing epoxy resin composition capable of obtaining semiconductor devices having high reliability which does not cause fluctuations of positioning of semiconductor elements due to the resin flow at the time of sealing and chip chilling such as dislocation of wiring. SOLUTION: A semiconductor sealing resin composition which comprises an epoxy resin, a phenolic resin, a hardening accelerator and an inorganic filler possesses such properties that (X) the viscosity expressed by a flow tester viscosity at 175 deg.C is 100-500 P; (Y) the minimum melt viscosity in the temperature variance in viscosity at a shear rate of 5(1/s) measured by a dynamic viscoelasticity measuring device is 1×105 P or less; and (Z) the viscosity ratio (Z1/Z2) of the viscosity (Z1) at 90 deg.C to the viscosity (Z2) at 110 deg.C at a shear rate of 5 (1/s) measured by a dynamic viscoelasticity measuring device is 2.0 or more.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an epoxy resin composition for semiconductor encapsulation, which can improve the occurrence of defects (chip tilt) during molding by resin encapsulation such as transfer molding and can impart high reliability, and The present invention relates to a semiconductor device obtained by using it.

[0002]

2. Description of the Related Art Conventionally, transistors, ICs, LSIs
From the viewpoint of protection from the external environment and easy handling of the semiconductor element, the semiconductor element such as is sealed in a plastic package represented by a dual in-line package (DIP) or the like to be a semiconductor device.

An epoxy resin composition has hitherto been used as a sealing material for the plastic package.

[0004]

However, in a semiconductor device obtained by resin-sealing a semiconductor element by transfer molding or the like using a conventionally used sealing material, a molding die due to a resin flow during molding is used. The position of the semiconductor element that should be originally set in the mold may slightly change due to fluctuations in the semiconductor element in the mold, or the gold wire bonded by wire may be deformed. It was inferior to

The present invention has been made in view of such circumstances, and a highly reliable semiconductor device in which the position variation of a semiconductor element due to a resin flow at the time of resin sealing and a chip tilt such as a gold wire flow does not occur. It is an object of the present invention to provide an epoxy resin composition for semiconductor encapsulation capable of obtaining the above and a semiconductor device obtained by using the same.

[0006]

In order to achieve the above object, the present invention provides a semiconductor encapsulating epoxy resin composition containing an epoxy resin, a phenol resin, a curing accelerator and an inorganic filler. The first gist is to have the characteristics (X) to (Z). (X) The flow tester has a viscosity of 50 to 500 poise at 175 ° C. (Y) Shear rate 5 (1 /
The minimum melt viscosity is 1 × 1 in the temperature dispersion of viscosity in s).
Less than 0 ⁵ poise. (Z) Shear rate measured by a dynamic viscoelasticity measuring device 5 (1 /
In (s), the viscosity ratio (Z1 / Z2) of the viscosity (Z1) at 90 ° C. and the viscosity (Z2) at 110 ° C. is 2.0 or more.

A second aspect of the present invention is a semiconductor device obtained by encapsulating a semiconductor element using the epoxy resin composition for encapsulating a semiconductor.

That is, the inventors of the present invention obtain a highly reliable semiconductor device by preventing the position variation of a semiconductor element and the occurrence of a chip tilt such as a gold wire flow which occur during resin sealing by transfer molding or the like. Therefore, research was repeated focusing on the viscosity characteristics of the epoxy resin composition as a sealing material. As a result, the flow tester viscosity at 175 ° C. [characteristic (X)], the minimum melt viscosity measured by a dynamic viscoelasticity measuring device [characteristic (Y)], and the viscosity at 90 ° C. (Z1)
And the viscosity ratio of the viscosity (Z2) at 110 ° C (Z1 / Z
2) The inventors have found that when the [characteristic (Z)] is set in a specific range, the above problem does not occur and a semiconductor device having high reliability can be obtained, and the present invention has been completed.

By setting the content of the inorganic filler, which is a constituent of the epoxy resin composition for semiconductor encapsulation, within a specific range, the water absorption of the package is suppressed and the reliability during mounting is increased. You will be able to keep.

Further, as a curing accelerator which is a constituent component of the epoxy resin composition for semiconductor encapsulation, a curing has a core / shell structure in which a core portion made of a curing accelerator is covered with a shell portion made of a synthetic resin. By using the accelerator-containing microcapsules, it becomes possible to perform the hot melt kneading time during the kneading of the constituent components of the epoxy resin composition longer than before, and further, the melt kneading temperature can be set high. Therefore, it becomes easy to obtain an epoxy resin composition having the viscosity characteristics (X) to (Z) described above.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described.

The epoxy resin composition for semiconductor encapsulation of the present invention comprises an epoxy resin (component A), a phenol resin (component B), a curing accelerator (component C), and an inorganic filler (component D). It can be obtained by using it, and is usually in the form of powder or tablets formed by tableting.

The epoxy resin (component A) is not particularly limited, and various conventionally known epoxy resins can be used. Examples thereof include o-cresol novolac type epoxy resin, phenol novolac type epoxy resin, biphenyl type epoxy resin, bisphenol A type epoxy resin, and naphthalene type epoxy resin. These epoxy resins may be used alone or in combination of two or more. Among them, the biphenyl type epoxy resin represented by the following general formula (1) is preferably used. In particular, a biphenyl type epoxy resin in which R _{1 to} R ₄ are all methyl groups is preferable.

[0014]

[Chemical 1]

The phenol resin (component B) used together with the epoxy resin (component A) acts as a curing agent for the epoxy resin, and is not particularly limited, and various conventionally known phenol resins can be used. A resin having a phenolic hydroxyl group. Examples thereof include novolac type resins such as cresol novolac resins, xylylene-modified phenol resins such as phenol aralkyl resins, terpene-modified phenol resins, dicyclopentadiene-modified phenol resins and the like. These phenol resins may be used alone or in combination of two or more. Among them, when the biphenyl type epoxy resin represented by the general formula (1) is used as the epoxy resin, it is preferable to use the phenol aralkyl resin represented by the following general formula (2) as the phenol resin.

[0016]

[Chemical 2]

The mixing ratio of the epoxy resin (component A) and the phenol resin (component B) is such that the hydroxyl group in the phenol resin is 0.0.1 per equivalent of the epoxy group in the epoxy resin.
It is preferable to add 8 to 1.2 equivalents. More preferred is 0.9 to 1.1 equivalents.

Examples of the curing accelerator (component C) used together with the components A and B include amines, imidazoles, phosphine compounds, organic phosphorus compounds such as quaternary phosphonium compounds, and the like.

Further, the following microcapsule type can be used as the curing accelerator.
That is, the microcapsule type curing accelerator has a core / shell structure in which the core portion made of the curing accelerator is covered with the shell portion made of synthetic resin. It is preferable to use this microcapsule type curing accelerator because the epoxy resin composition for semiconductor encapsulation having the characteristics (X) to (Z), which is a feature of the present invention, can be easily obtained. is there.

The curing accelerator contained as the core portion is not particularly limited and conventionally known ones can be used. In this case, those having a liquid state at room temperature are preferable from the viewpoint of workability when preparing the microcapsules and the characteristics of the obtained microcapsules. The liquid at room temperature means that the property of the curing accelerator itself is 15 to 40 ° C.
In addition to the case of showing a liquid state at any temperature within the range of 10 to 40, even if it is a solid at any temperature within the range of 15 to 40 ° C., it is dissolved or dispersed in an arbitrary organic solvent or the like to form a liquid state. Including things.

As described above, examples of the curing accelerator include amines, imidazoles, phosphorus-based, boron-based and phosphorus-boron-based curing accelerators. Specifically, alkyl-substituted guanidines such as ethylguanidine, trimethylguanidine, phenylguanidine, and diphenylguanidine, 3- (3,4-dichlorophenyl) -1,1-dimethylurea, 3-phenyl-
1,1-dimethylurea, 3- (4-chlorophenyl)-
3-Substituted phenyl-1,1-dimethylurea, etc.
Dimethyl ureas, 2-methyl imidazoline, 2-phenyl imidazoline, 2-undecyl imidazoline, 2-heptadecyl imidazoline and other imidazolines, 2-amino pyridine and other monoamino pyridines, N, N-dimethyl-N- ( 2-hydroxy-3-allyloxypropyl)
Amine imides such as amine-N'-lactoimide, ethylphosphine, propylphosphine, butylphosphine, phenylphosphine, trimethylphosphine, triethylphosphine, tributylphosphine, trioctylphosphine, triphenylphosphine, tricyclohexylphosphine, triphenylphosphine / tri Phenylborane complex, organic phosphorus compounds such as tetraphenylphosphonium tetraphenylborate, diaza such as 1,8-diazabicyclo [5,4,0] undecene-7,1,4-diazabicyclo [2,2,2] octane Examples thereof include bicycloundecene compounds. Among them, organic phosphorus compounds such as triphenylphosphine and imidazole compounds are preferably used from the viewpoint of easy production of the curing accelerator-containing microcapsules and easy handling. These may be used alone or in combination of two or more.

The organic solvent that can be included in the shell portion (wall film) of the microcapsule is not particularly limited as long as it is liquid at room temperature, but at least the shell portion (wall film) is not dissolved. You need to choose one. Specifically, ethyl acetate, methyl ethyl ketone,
In addition to organic solvents such as acetone, methylene chloride, xylene, toluene and tetrahydrofuran, oils such as phenylxylylethane and dialkylnaphthalene can be used.

Examples of the thermoplastic resin forming the shell portion (wall film) include polyurea, polyurethane, amino resin, acrylic resin and the like. Of these, polyurea is preferable in consideration of stability during storage and easiness of breaking the shell portion during molding of the cured product.

As the polyurea, a polymer having a repeating unit represented by the following general formula (3) as a main constituent is particularly preferable.

[0025]

[Chemical 3]

As described above, in the equation (3), R ₅ ,
R ₆ is a hydrogen atom or a monovalent organic group,
Is a divalent organic group.

The polymer having the repeating unit represented by the above formula (3) as a main constituent component can be obtained, for example, by a polyaddition reaction between polyvalent isocyanates and polyvalent amines.
Alternatively, it can be obtained by reacting polyisocyanates with water.

The above-mentioned polyisocyanates may be compounds having two or more isocyanate groups in the molecule, and specifically, m-phenylene diisocyanate, p-phenylene diisocyanate, 2,4-tolylene diisocyanate. , 2,6-tolylene diisocyanate, naphthalene-1,4-diisocyanate, diphenylmethane-4,4'-diisocyanate, 3,3'-dimethoxy-4,4'-biphenyldiisocyanate,
3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, xylylene-1,4-diisocyanate, 4,4'-diphenylpropane diisocyanate,
Trimethylene diisocyanate, hexamethylene diisocyanate, propylene-1,2-diisocyanate,
Butylene-1,2-diisocyanate, cyclohexylene-1,2-diisocyanate, cyclohexylene-
Diisocyanates such as 1,4-diisocyanate, p
-Phenylene diisothiocyanate, xylylene-1,
Triisocyanates such as 4-diisothiocyanate and ethylidyne diisothiocyanate, tetraisocyanates such as 4,4′-dimethyldiphenylmethane-2,2 ′, 5,5′-tetraisocyanate, hexamethylene diisocyanate and hexanetriol Addition of
Addition product of 2,4-tolylene diisocyanate and prenzcatechol, addition product of tolylene diisocyanate and hexanetriol, addition product of tolylene diisocyanate and trimethylolpropane, addition product of xylylene diisocyanate and trimethylolpropane, hexa Like trimer of aliphatic polyisocyanate such as adduct of methylene diisocyanate and trimethylol propane, triphenyl dimethylene triisocyanate, tetraphenyl trimethylene tetraisocyanate, pentaphenyl tetramethylene pentaisocyanate, lysine isocyanate, hexamethylene diisocyanate. And isocyanate prepolymers. These may be used alone or in combination of two or more.

Among the above-mentioned polyvalent isocyanates, from the viewpoint of film-forming property and mechanical strength when preparing microcapsules, an adduct of tolylene diisocyanate and trimethylol propane and an adduct of xylylene diisocyanate and trimethylol propane. It is preferable to use an isocyanate prepolymer represented by polymethylene polyphenyl isocyanate such as triphenyl dimethylene triisocyanate.

On the other hand, the polyvalent amines to be reacted with the polyvalent isocyanates may be compounds having two or more amino groups in the molecule, specifically, diethylenetriamine, triethylenetetramine, tetraethylenepenta. Min, 1,6-hexamethylenediamine, 1,8
-Octamethylenediamine, 1,12-dodecamethylenediamine, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, o-xylylenediamine, m-xylylenediamine, p-xylylenediamine, menthanediamine, bis (4-amino-3-methylcyclohexyl) methane, isophoronediamine, 1,3
-Diaminocyclohexane, spiro acetal type diamine and the like. These may be used alone or in combination of two or more.

In the reaction between the polyvalent isocyanate and water, first, an amine is formed by hydrolysis of the polyvalent isocyanate and the amine reacts with an unreacted isocyanate group (so-called self-polyaddition reaction). As a result, a polymer having the repeating unit represented by the general formula (3) as a main constituent is formed.

The above-mentioned hardening accelerator-containing microcapsules are
There is no particular limitation as long as it can be microencapsulated, and it can be prepared by various conventionally known methods. In particular, it is preferable to form the shell part (wall film) by using the interfacial polymerization method and to microcapsulate the shell part (wall film) from the viewpoint of homogenization of the shell part (wall film) and adjustment of the wall film thickness.

The curing accelerator-containing microcapsules obtained by the interfacial polymerization method are obtained, for example, as follows.
That is, using a liquid curing accelerator as a core component, polyvalent isocyanates are dissolved therein. The solution thus obtained is oily and is dispersed as an oil phase in the water phase in the form of oil droplets to prepare an O / W type (oil phase / water phase type) emulsion. At this time, the average particle diameter of each dispersed oil droplet is 0.05 to 50 μm, preferably 0.05 to 10 μm.
From the viewpoint of the stability of the emulsion during the polymerization, it is preferable that it is about m.

On the other hand, when a solid curing accelerator is dissolved in an organic solvent to form a core component, an S / O / W (solid phase / oil phase / water phase) type emulsion is obtained. Also, this emulsion type is when the curing accelerator is lipophilic,
When the curing accelerator has hydrophilicity, it is difficult to form into the above emulsion type, but in this case, by adjusting the solubility, an O / O (oil phase / oil phase) emulsion type or S / O / O (solid phase / oil phase / oil phase) emulsion type may be used for interfacial polymerization.

Then, a polyvalent amine or a polyhydric alcohol is added to the aqueous phase of the emulsion to cause an interfacial polymerization with the polyvalent isocyanate in the oil phase to carry out a polyaddition reaction, preferably a polyurea-based one. A curing accelerator-containing microcapsule having a polymer as a shell portion (wall film) can be obtained.

The thus-obtained hardening accelerator-containing microcapsules have a core / shell structure, and the hardening accelerator is included as a core component in the shell portion. The hardening accelerator-containing microcapsules can be isolated by a conventionally known means, for example, drying after centrifugal separation or spray drying. Further, for example, it can be dissolved and mixed in the epoxy resin or the curing agent. At this time, if necessary, the organic solvent in the microcapsules can be removed together with a means such as drying under reduced pressure.

The average particle size of the curing accelerator-containing microcapsules is 0 in consideration of the stability of the microcapsules themselves, the shearing force applied during the production of the epoxy resin composition, the uniform dispersibility, etc., as described later. It is preferably set in the range of 0.05 to 10 μm, and more preferably in the range of 0.1 to 4 μm. Furthermore, it is preferable to set the maximum particle diameter of the microcapsules containing the curing accelerator to be 20 μm or less. That is, by setting the average particle diameter of the microcapsules containing the curing accelerator in the above range, it is possible to suppress microcapsule breakage due to shearing force during the production of the epoxy resin composition. Further, by setting the average particle size and the maximum particle size to 20 μm or less, uniform dispersion in the epoxy resin can be achieved.
In the present invention, the shape of the hardening accelerator-containing microcapsules is preferably spherical, but may be elliptical. When the particle size of the microcapsules is not a spherical shape but an elliptical shape, a flat shape, or the like, and the particle diameter is not uniformly determined, the simple average value of the longest diameter and the shortest diameter is taken as the average particle diameter.

The amount of the curing accelerator contained in the curing accelerator-containing microcapsules is preferably set to 5 to 70% by weight, particularly preferably 10 to 50% by weight, based on the total amount of the curing accelerator-containing microcapsules. %. That is, when the content of the curing accelerator is less than 5% by weight, the curing reaction takes too long and the reactivity becomes poor,
On the other hand, if the amount of the curing accelerator included exceeds 70% by weight, the thickness of the shell portion (wall film) may be too thin, and the isolation property and mechanical strength of the included curing accelerator (core component) may be poor. Because.

Further, the ratio of the thickness of the shell portion (wall film) to the particle size of the above-mentioned hardening accelerator-containing microcapsules is 3 to 2.
It is preferably set to 5%, particularly preferably 5 to 2
It is set to 5%. That is, if the above ratio is less than 3%, sufficient mechanical strength cannot be obtained with respect to the shear added in the kneading step during the production of the epoxy resin composition, and 25
This is because if the content exceeds%, the release of the included curing accelerator tends to be insufficient.

The inorganic filler (component D) used together with the components A to C is not particularly limited, and conventionally known ones can be used. For example, silica such as fused silica powder or crystalline silica powder can be used. Powder, alumina powder or the like is used. These inorganic fillers are crushed,
Any of spherical particles and ground particles can be used. And these are used individually or in mixture of 2 or more types. And, as the whole inorganic filler, it is preferable to use one having an average particle size in the range of 6 to 40 μm from the viewpoint of improving the fluidity. Furthermore, among the above-mentioned inorganic fillers, specifically, from the viewpoint of good fluidity, a crystalline silica that has been subjected to attrition treatment,
It is particularly preferable to use spherical fused silica powder.

The blending amount of the above-mentioned inorganic filler (D component) is
It is preferably set to 80 to 92% by weight, particularly preferably 87 to 92% by weight in the epoxy resin composition.
Is. That is, if the content of the inorganic filler (D component) is less than 80% by weight, the water absorption of the package after molding tends to increase and the reliability during mounting tends to decrease. This is because there is a tendency to be inferior in sex.

Further, in addition to the above-mentioned components A to D, other additives can be appropriately added to the epoxy resin composition for semiconductor encapsulation of the present invention, if necessary. In addition, it is preferable to set the blending amount of each of the other additives in the range of 0.01 to 2% by weight in the entire epoxy resin composition.

Examples of the above-mentioned other additives include a releasing agent, a flame retardant, a coloring agent, a silane coupling agent, and a stress reducing agent.

Examples of the releasing agent include long-known carboxylic acids such as stearic acid and palmitic acid, metal salts of long-chain carboxylic acids such as zinc stearate and calcium stearate, polyethylene wax and carnauba wax.
Waxes such as montan wax can be used.

Examples of the flame retardant include brominated epoxy resin, and antimony trioxide, antimony pentoxide and the like can be used as the flame retardant auxiliary.

Further, examples of the colorant include carbon black and the like.

Examples of the stress reducing agent include butadiene rubber such as methyl acrylate-butadiene-styrene copolymer and methyl methacrylate-butadiene-styrene copolymer, and silicone compounds. Further, an ion trap agent such as hydrotalcites or bismuth hydroxide may be blended for the purpose of improving reliability in the moisture resistance reliability test.

The epoxy resin composition for semiconductor encapsulation of the present invention can be produced, for example, as follows.
That is, first, the components A to D and the other additives described above are appropriately blended, and the mixture is melt-mixed in a heating state by applying it to a kneading machine such as a mixing roll, and this is cooled to room temperature and then pulverized by a known means, It can be manufactured by a series of steps of tableting as necessary.

When the curing accelerator-containing microcapsules are used as the curing accelerator, first, the curing accelerator-containing microcapsules are prepared according to the above-mentioned manufacturing method. Then, the remaining blending ingredients are blended, and the mixture is melt-mixed in a heating state by applying it to a kneading machine such as a mixing roll, and the mixture is cooled to room temperature and then pulverized by a known means, followed by tableting as necessary. It can be manufactured by the process of. Furthermore, as well as using the curing accelerator-containing microcapsules, as an inorganic filler,
It is preferable to use two or more kinds of silica powder having different average particle diameters in combination. For example, it is preferable from the viewpoint of fluidity that spherical fused silica powder having a large average particle diameter and crushed fused silica powder having an average particle diameter smaller than that are used in combination.

In the process for producing the epoxy resin composition for semiconductor encapsulation of the present invention using the above-mentioned curing accelerator-containing microcapsules, the temperature conditions during melt mixing with a kneader or the like are as follows:
In general, the temperature is set higher than the temperature at the time of manufacturing a normal encapsulant and the kneading time is set to be long in a temperature range in which the curing accelerator-containing microcapsules are not destroyed. That is, by using the curing accelerator-containing microcapsules, it is possible to set higher than the temperature conditions in the case of using a normal curing accelerator,
And it becomes possible to knead for a long time. This makes it possible to improve the wettability of the organic component and the inorganic component during kneading. When the wettability of the interface of the inorganic component is improved, the shear rate 5 (1
/ S), the viscosity ratio (Z1 / Z2) of the viscosity at 90 ° C. (Z1) and the viscosity at 110 ° C. (Z2) becomes large, and a material having excellent moldability can be obtained. Note that the details will be disclosed in Examples described later.

The epoxy resin composition for semiconductor encapsulation of the present invention must have the following properties (X) to (Z).

(X) Flow tester 17 shown by viscosity
Viscosity at 5 ° C is 50-500 poise. (Y) Shear rate 5 (1 /
The minimum melt viscosity is 1 × 1 in the temperature dispersion of viscosity in s).
Less than 0 ⁵ poise. (Z) Shear rate measured by a dynamic viscoelasticity measuring device 5 (1 /
In (s), the viscosity ratio (Z1 / Z2) of the viscosity (Z1) at 90 ° C. and the viscosity (Z2) at 110 ° C. is 2.0 or more.

In the above characteristic (X), the viscosity measured by a flow tester viscometer under the temperature condition of 175 ° C. (for example, a Takashi type flow tester manufactured by Shimadzu Corporation) is 50.
Must be in the range of ~ 500 poise. Particularly preferably, it is 50 to 300 poise. That is, the viscosity is 50
If it is less than poise, the viscosity at the time of molding is too low and the problem of voids due to entrainment of air occurs, and if it exceeds 500 poise, the viscosity is too high and the gold wire flow and unfilling failure occur as described above. .

The above characteristic (X) can be measured as follows. That is, the powder (6
2g of mesh pass product) 100kgf / c at 20 ° C
Molding is performed at a pressure of m ² to prepare a cylindrical sample having a diameter of 9.8 mm. Then, the viscosity of this sample at 175 ° C. is measured using a flow tester viscometer (for example, a high-lowering type flow tester manufactured by Shimadzu Corporation, CFT-100 type). As for other conditions at the time of measurement, the nozzle of the soybean used has a diameter of 1.0 mm, a length of 10.0 mm, and a load of 10 kg on the sample.

In the above characteristic (Y), the minimum melt viscosity is not more than 1 × 10 ⁵ poise in the temperature dispersion of the viscosity at a shear rate of 5 (1 / s) measured by a dynamic viscoelasticity measuring device. I won't. Particularly preferably, the minimum melt viscosity is 5
It is not more than × 10 ⁴ poise. That is, if the minimum melt viscosity exceeds 1 × 10 ⁵ poise, the viscosity when flowing inside the cavity during molding becomes high. From this fact, the fact that the minimum melt viscosity is large means that the characteristics of the gold wire flow and the tip tilt during molding are deteriorated.

Furthermore, in the above characteristic (Z), at a shear rate of 5 (1 / s) measured by a dynamic viscoelasticity measuring device, 9
Viscosity at 0 ° C (Z1) and viscosity at 110 ° C (Z
The viscosity ratio (Z1 / Z2) of 2) must be 2.0 or more. Particularly preferably, Z1 / Z2 is 2.5 or more. That is, when Z1 / Z2 is less than 2.0, the effect of decreasing the viscosity as the temperature rises is small, and the minimum melt viscosity increases. Therefore, conversely Z
The small 1 / Z2 value means that the gold wire flow and the tip tilt during molding are inferior.

The above characteristics (Y) and (Z) are measured as follows. That is, first, pellets (diameter 25 mm, weight 2 g) to be the sealing material are prepared. The above-mentioned pellet is 100 kgf / cm at 20 ° C. of 2 g of epoxy resin composition powder (6 mesh pass product).
^{It is} molded at a pressure of ² to prepare a disc-shaped sample having a diameter of 25 mm. Then, using a dynamic viscoelasticity measuring instrument (manufactured by Rheometrics) under the condition of a shear rate of 5 (1 / s), as shown in FIG.
And clamp it between the lower plate 2 and apply a strain amount of 2%,
While increasing the temperature (16 ° C./min), the viscosity is calculated from the torque.

There is no particular limitation on the sealing of the semiconductor element using such a semiconductor sealing epoxy resin composition, and it is carried out by a known molding method such as ordinary transfer molding. You can

Next, examples will be described together with comparative examples.

First, the following compounds were prepared prior to the examples.

[Epoxy resin] Biphenyl type epoxy resin represented by the following formula (4) (epoxy equivalent 200)

[0062]

[Chemical 4]

[Phenol Resin] Phenol aralkyl resin represented by the general formula (2) (wherein n = 0 to 2)
1, hydroxyl equivalent 175)

[Inorganic filler D1] Spherical fused silica powder (average particle size 30 μm)

[Inorganic filler D2] Spherical fused silica powder (average particle size 15 μm)

[Inorganic filler D3] Crushed fused silica powder (average particle size 15 μm)

[Inorganic filler D4] Crushed fused silica powder (average particle size 6 μm)

[Release Agent] Polyethylene Wax

[Curing Accelerator-Containing Microcapsules] 11 parts by weight of an adduct of 3 mol of xylylenediisocyanate and 1 mol of trimethylolpropane, 4.6 parts by weight of an adduct of 3 mol of tolylenediisocyanate and 1 mol of trimethylolpropane. Was uniformly dissolved in a mixed solution of 7 parts by weight of triphenylphosphine as a curing accelerator and 3.9 parts by weight of ethyl acetate to prepare an oil phase.

Next, an aqueous phase consisting of 100 parts by weight of distilled water and 5 parts by weight of polyvinyl alcohol was separately prepared, and the above-prepared oil phase was added thereto and emulsified with a homomixer to obtain an emulsion state. Was charged into a polymerization reactor equipped with a reflux tube, a stirrer, and a dropping funnel.

On the other hand, 10 parts by weight of an aqueous solution containing 3 parts by weight of triethylenetetramine was prepared, placed in a dropping funnel provided in the above polymerization reactor, added dropwise to the emulsion in the reactor and kept at 70 ° C. for 3 hours. Interfacial polymerization was performed to obtain an aqueous suspension of a microcapsule type curing accelerator. Subsequently, after removing polyvinyl alcohol and the like in the aqueous phase by centrifugation, 100 parts by weight of distilled water was added and dispersed again to obtain a suspension. The hardening accelerator-containing microcapsules thus obtained were separated as free-flowing powdery particles by repeatedly separating and washing with water after centrifugation. The average particle size of the obtained particles was 2 μm.

[0072]

Examples 1 to 5 and Comparative Examples 1 to 4 The components shown in Tables 1 and 2 below were blended in the proportions shown in the same table, kneaded with a mixing roll machine, cooled, and then pulverized to obtain the purpose. A powdery epoxy resin composition was obtained. The kneading conditions (kneading temperature, kneading time) using the above mixing roll machine are also shown in Tables 1 and 2 below.

[0073]

[Table 1]

[0074]

[Table 2]

Using the thus obtained epoxy resin compositions for semiconductor encapsulation of each Example product and Comparative Example product, characteristics were evaluated according to the following methods. The results are also shown in Tables 3 to 4 below.

[Flow Tester Viscosity 175 ° C.
Viscosity] The measurement was performed according to the method described above using a powdery epoxy resin composition having a 6-mesh pass. As the flow tester viscometer, a high-down type flow tester (CFT-100 type) manufactured by Shimadzu Corporation was used.

[Minimum Melt Viscosity] A powdery epoxy resin composition having a 6-mesh pass was used and measured according to the method described above. That is, a pellet having a diameter of 25 mm and a weight of 2 g is
It was produced by cold forming (pressure: 100 kg / cm ² ).
Then, using the above pellets, according to the method described above (see FIG. 1), measurement was performed using a dynamic viscoelasticity measuring device (manufactured by Rheometrics) under the following conditions. Temperature rise: 16 ° C / min Frequency: 0.8 rad / s (shear rate 5 s ^-1 ) Strain: 2%

[Viscosity Ratio] A powdery epoxy resin composition having a 6-mesh pass was used and measured according to the method described above. That is, a pellet having a diameter of 25 mm and a weight of 2 g was prepared by cold forming (pressure: 100 kg / cm ² ). Then, using the above pellets, according to the method described above (see FIG.
), Using the above dynamic viscoelasticity measuring device, under the following conditions,
The viscosity at 90 ° C. (Z1) and the viscosity at 110 ° C. (Z2) were measured, and the ratio thereof was calculated. Temperature rise: 16 ° C / min Frequency: 0.8 rad / s (shear rate 5 s ^-1 ) Strain: 2%

Further, a semiconductor device [160-pin four-way flat package: QFP160] was prepared by using the powdery epoxy resin composition obtained in each of the above Examples and Comparative Examples.
A pin (28 mm × 28 mm × thickness 3.0 mm) was produced by transfer molding (conditions: 175 ° C. × 90 seconds) and subsequent after-curing at 175 ° C. × 5 hours.

[Gold Wire Deformation Rate] As shown in FIG. 2, the QFP1 having the 9.5 mm square die pad 10 used above.
A gold wire (diameter 30 μm × maximum length 3.8 mm) 14 was attached to a 60-pin frame, and this was resin-sealed with the epoxy resin composition to prepare a package.
In FIG. 2, reference numeral 15 is a semiconductor chip, and 16 is a lead pin. Then, the amount of gold wire flow of the manufactured package was measured using an X-ray analyzer. The measurement was performed by selecting 10 gold wires from each package and measuring the amount of flow of the gold wire 14 from the front direction as shown in FIG. Then, the value of the maximum amount of flow of the gold wire 14 was set as the value (dmm) of the flow of gold wire of the package, and the gold wire deformation rate [(d / L) × 100] was calculated. In addition, L shows the distance (mm) between the gold wire wires 14.

[Molding Defect Evaluation] First, the number of defective moldings (out of 100) of the obtained semiconductor devices was measured. That is, the QFP160pin was molded to evaluate the formation of voids. Then, the number of defects generated in the semiconductor device was counted. The formation of the voids is
It was measured with a soft X-ray device, and a molded product having a diameter of 0.1 mm or more was regarded as defective.

[Amount of Deformation of Die Pad] Using each of the above epoxy resin compositions, a semiconductor chip 15 having a shape shown in FIG.
Q with a 9.5 mm square die pad 10 on which is mounted
The FP160pin11 was molded, the package 11 was cut (the cut surface is indicated by a dashed line), the cut surface was observed, and the deformation amount of the die pad was measured by the difference from the design value of the die pad. That is, as shown in FIG.
Regarding the package in the state where the die pad shift occurs, the thickness of the resin layer (thickness a
μm) was measured. On the other hand, as shown in FIG. 5B, the thickness (thickness b μm) of the resin layer under the four corners of the die pad 10 was measured in a normal package in which the die pad shift did not occur. Such measurement was carried out at all four corners of the die pad 10, and the difference (ab) between these measured values and the normal product was obtained as an absolute value, and this was shown as an average value.

The evaluation results of these semiconductor devices are shown in Table 3 below.
~ Also shown in Table 4.

[0084]

[Table 3]

[0085]

[Table 4]

From the results shown in Tables 3 to 4, the gold wire was not deformed and voids were generated very little in the products of Examples satisfying all of the above characteristics (X) to (Z). Further, it can be seen that a semiconductor device having a small die pad shift and high reliability was obtained. On the other hand, it was revealed that the comparative example product was inferior in at least one of gold wire flow, void, and die pad deformation amount.

[0087]

As described above, since the epoxy resin composition for semiconductor encapsulation of the present invention has the above-mentioned characteristics (X) to (Z), when this resin composition is used as a sealing material. As a result, a semiconductor device having high reliability can be obtained without causing a positional change of a semiconductor element due to a resin flow at the time of resin sealing and a chip tilt such as a gold wire flow.

By setting the content of the inorganic filler, which is a constituent component of the epoxy resin composition for semiconductor encapsulation, within a specific range, the water absorption of the package is reduced and the reliability at the time of mounting is increased. be able to.

Further, as a curing accelerator which is a constituent component of the epoxy resin composition for semiconductor encapsulation, a curing has a core / shell structure in which a core portion made of a curing accelerator is covered with a shell portion made of a synthetic resin. By using the accelerator-containing microcapsules, it becomes possible to perform the hot melt kneading time during the kneading of the constituent components of the epoxy resin composition longer than before, and further, the melt kneading temperature can be set high. Therefore, it becomes easy to obtain an epoxy resin composition having the viscosity characteristics (X) to (Z) described above.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a method for measuring characteristics (Y) and (Z) of the present invention.

FIG. 2 QFP16 used to measure the amount of gold wire flow
It is a front view which shows 0 pin.

FIG. 3 is an explanatory diagram showing a method for measuring the amount of flow of a gold wire.

FIG. 4 is a front view showing a QFP160pin molded using an epoxy resin composition for semiconductor encapsulation.

5A and 5B are explanatory diagrams showing a method of measuring a die pad shift, wherein FIG. 5A is a sectional view showing a state in which a die pad shift has occurred, and FIG. 5B is a sectional view showing a normal state.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 23/31 (72) Inventor Tsutomu Nishioka 1-2 1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation (72) Inventor Tadaaki Harada 1-2 1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Co., Ltd. (72) Inventor Toshitsugu Hosokawa 1-2 1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation ( 72) Inventor Kazuhiro Ikemura, 1-2, Shimohozumi, Ibaraki-shi, Osaka, Nitto Denko Corporation (72) Inventor, Sadahito Misumi 1-2-1, Shimohozumi, Ibaraki-shi, Osaka (72) Inventor Shinichi Oizumi 1-2-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto Denko Corporation

Claims (4)

[Claims] 1. An epoxy resin composition for semiconductor encapsulation, which comprises an epoxy resin, a phenol resin, a curing accelerator and an inorganic filler, and has the following characteristics (X) to (Z). The epoxy resin composition for semiconductor encapsulation. (X) The flow tester has a viscosity of 50 to 500 poise at 175 ° C. (Y) The minimum melt viscosity is 1 × 10 ⁵ poise or less in temperature dispersion of viscosity at a shear rate of 5 (1 / s) measured by a dynamic viscoelasticity measuring device. (Z)
The viscosity ratio (Z1 / Z2) of the viscosity (Z1) at 90 ° C. and the viscosity (Z2) at 110 ° C. at a shear rate of 5 (1 / s) measured by a dynamic viscoelasticity measuring device is 2.0 or more. 2. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the content of the inorganic filler is 80 to 92% by weight based on the whole epoxy resin composition. 3. The hardening accelerator-containing microcapsule having a core / shell structure in which the hardening accelerator has a core portion made of a hardening accelerator covered with a shell portion made of a synthetic resin. Epoxy resin composition for semiconductor encapsulation. 4. A semiconductor device obtained by encapsulating a semiconductor element using the epoxy resin composition for encapsulating a semiconductor according to claim 1.