JP2000256642A - Conductive adhesive and semiconductor device made by using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an adhesive excellent in workability, shelf stability, and the relaxation of thermal stress and capable of giving high bonding strength by blending a modified silicon compound having terminal epoxy groups, diallyl bisphenol F and dicyandiamide, 2-phenyl-4-methyl-5-hydroxymethylimidazole, and a conductive filler as the essential constituents. SOLUTION: The modified silicon compound having terminal epoxy groups is obtained by reacting a dimethylpolysiloxane represented by the formula, having terminal hydroxyphenyl groups and a weight-average molecular weight Mw of 2,000 to 10,000 with a mononuclear bisphenol F epoxy resin and has a weight-average molecular weight Mw of 12,000 to 26,000. In the formula R1 and R2 may be the same or different and are each a 1-20C divalent organic group; and n is an integer. The dimethylpolysiloxane of the formula preferably comprises one in which the content of residual impurities such as raw material allylphenol and an internal isomerized material is at most 10 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable for bonding a conductive adhesive, more specifically, a semiconductor element or a semiconductor module such as an IC or LSI to a supporting member such as a lead frame, a printed wiring board, and a heat dissipation base. The present invention relates to a low-stress conductive adhesive and a semiconductor device using the same.

[0002]

2. Description of the Related Art In recent years, a semiconductor element such as an IC or LSI and a supporting member such as a lead frame or a substrate have been replaced with an Au-Si eutectic method or a soldering method in view of workability and cost during mass production. A method using a conductive adhesive has been generalized.

[0003] In the field of electronic and electric components, demands for high density, high integration, light weight and compactness have made the wiring of semiconductor devices finer and the devices themselves thin and small, and at the same time, large currents, In response to a demand for a large capacity, a semiconductor element becomes large in size and generates high heat. In addition, the lead frame on which the semiconductor element is mounted is made of low-cost copper with good thermal conductivity instead of the conventional 42 alloy, and the substrate tends to have higher density and higher multilayer.

[0004] Therefore, when these electric and electronic parts are mounted using a conventional conductive adhesive, the stress due to the difference in the thermal expansion coefficient between the electronic parts and the support member due to environmental temperature changes and heat generation during operation. Distortion occurs, and warpage and cracks occur not only in the electronic component and the support member but also in the adhesive layer. For this reason, there is a problem that the reliability of the electronic component is reduced.

[0005] In other words, heretofore, low elasticity, high adhesiveness, low viscosity, excellent workability, and long-term storage stability have been obtained so far that the stress generated between these electronic components and the support member can be absorbed. There was no conductive adhesive having excellent properties.

[0006] In order to solve such a problem, there are provided (1) an epoxy-modified silicone obtained by reacting a dimethylsiloxane having a carboxyl group at both ends with an epoxy resin having two or more epoxy groups in one molecule. A conductive adhesive containing a compound, a curing agent and a conductive filler (JP-A-3-43482), (2)
A conductive resin paste comprising a silver powder, an epoxy resin, a curing agent and a flexibility-imparting agent, wherein the flexibility-imparting agent is a dimethylsiloxane compound having an epoxy group, an amino group or a hydroxy group (Japanese Patent Application Laid-Open No. No. 63-161014), (3) a flexibilizing agent comprising a reaction product of a silicone oil having two hydroxyphenyl groups in one molecule and an epoxy resin, a microencapsulated imidazole derivative and / or a melting point of 70 ° C. or more A semiconductor device in which a semiconductor chip and a lead frame are connected via a low-stress adhesive resin composition containing a curing agent comprising a solid imidazole derivative of
-1262020), and (4) a silicone-modified epoxy resin obtained by reacting a dimethylpolysiloxane having a hydroxyphenyl group at both terminals with an epoxy resin having two or more epoxy groups in one molecule, and a curing agent. Silicone-modified epoxy resin composition (Japanese Unexamined Patent Publication No.
No. 58827) has been proposed.

However, in the adhesive described in the publication (1), since the carboxyl group at the end of the silicone and the epoxy group of the epoxy resin are reacted, the reaction product takes an ester bond and is easily hydrolyzed. There was a problem that dimethylsiloxane was separated.

In the paste described in the publication (2), the mutual melting property of the dimethylsiloxane compound and the epoxy resin is low, and the epoxy resin and the silicone are not reacted beforehand. inside,
There was a problem that the epoxy resin of the matrix resin and the silicone were separated.

In the adhesive resin composition described in the publication (3), the so-called sea-island structure in which the epoxy-modified silicone oil flexibilizer does not mutually melt with the epoxy resin but is dispersed in the cured epoxy resin. Therefore, there is a problem that the elastic modulus of the cured product is high and a sufficient stress relaxation effect cannot be obtained.

In the epoxy resin composition described in the publication (4), a silicone obtained by reacting a dimethylpolysiloxane having a phenolic hydroxyl group at both terminals with an epoxy resin having two or more epoxy groups in one molecule. Although a modified epoxy resin is used, the viscosity and uniformity of the silicone-modified epoxy resin have not been studied. Further, no detailed study has been made on the blending amounts of a curing agent and a curing accelerator which give optimum performance (low viscosity, low stress, storage stability, adhesive strength) as a low stress conductive adhesive. Further, no study has been made on using a conductive adhesive as a semiconductor device.

[0011]

SUMMARY OF THE INVENTION In view of the above facts, the present invention has been made to solve the above-mentioned problems, and is intended to provide a completely uniform and low-viscosity solution of an epoxy-modified silicone compound at both ends. The curing agent and the curing accelerator are in a dispersed state in the matrix, so that the object is to provide a conductive adhesive having excellent workability, excellent storage stability, excellent thermal stress relaxation, and high adhesive strength. .

Still another object of the present invention is to provide a semiconductor device in which a semiconductor element or a semiconductor module and a supporting member are adhered to each other using the conductive adhesive.

[0013]

Means for Solving the Problems The conductive adhesive according to the present invention comprises (A) a general formula (1):

[0014]

Embedded image

(Wherein R ¹ and R ² each represent a divalent organic group having 1 to 20 carbon atoms, which may be the same or different, and n is an integer). Weight molecular weight Mw having a hydroxyphenyl group at a terminal is 2000
Epoxy-modified silicone compound obtained by reacting dimethylpolysiloxane of 10,000 to 10,000 with a mononuclear body of a bisphenol F type epoxy resin, having a weight molecular weight Mw
Is 12000-26000, (B) diallylbisphenol F and dicyandiamide, (C) 2-phenyl-4-methyl-5-hydroxymethylimidazole and (D) a conductive filler as essential components.

Also, (A) a compound having a weight molecular weight Mw having a hydroxyphenyl group at both terminals represented by the general formula (1)
Is a dimethylpolysiloxane of 2000 to 10000,
It is preferable that the residual amount of impurities such as allylphenol and internal isomers as raw materials is 10% by weight or less.

Further, the semiconductor device according to the present invention comprises:
The semiconductor element or the semiconductor module and the supporting member are bonded to each other using the conductive adhesive.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail.

Component (A) used in the conductive adhesive of the present invention
The two-terminal epoxy-modified silicone compound is (A)
General formula (1):

[0020]

Embedded image

(Wherein, R ¹ and R ² each represent a divalent organic group having 1 to 20 carbon atoms, which may be the same or different, and n is an integer). Weight average molecular weight having a hydroxyphenyl group at a terminal
Obtained by the reaction of 10,000 dimethylpolysiloxane with a mononuclear bisphenol F epoxy resin.

In the general formula (1), R ¹ and R ² represent a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group,
It is preferably a divalent organic group such as a heptamethylene group, an octamethylene group or a xylylene group, and more preferably a trimethylene group from the viewpoint of more effectively relaxing stress.

The dimethylpolysiloxane having a hydroxyphenyl group at both terminals represented by the general formula (1) preferably has a weight average molecular weight Mw of 2,000 to 10,000. More preferably, it is in the range of 4500 to 7500 having a large stress relaxation effect. That is, 1
When it exceeds 0000, it completely separates from the epoxy resin and does not react, becomes a cloudy state even with stirring, and completely separates during long-term storage. On the other hand, when it is less than 2,000, the epoxy resin and dimethylpolysiloxane react and mutually melt, but the reaction is further accelerated due to the generation of reaction heat, and the viscosity of the epoxy-modified silicone resin increases sharply and is obtained. The stress relaxation effect of the conductive adhesive tends to decrease. For this reason, the molecular weight of dimethylpolysiloxane having hydroxyphenyl groups at both ends is limited to the above range.

The dimethylsiloxane represented by the general formula (1) used in the present invention can be obtained by a method of hydrosilylating a siloxane having hydrogen bonded to allylphenol and silicon in the presence of a platinum-based catalyst.

In the dimethylpolysiloxane represented by the general formula (1), the residual amount of impurities such as raw materials such as allylphenol and internal isomers is preferably 10% by weight or less. That is, the residual amount of impurities is 10% by weight.
When the number is even greater, the reaction between the epoxy resin and the impurities is faster than the reaction between the epoxy resin and dimethylpolysiloxane, and a large number of compounds having a small molecular weight are generated, so that the reaction between the epoxy resin and dimethylpolysiloxane is easily inhibited. In addition, it becomes difficult to obtain uniformity of the entire resin solution. In addition, a conductive adhesive using such a non-uniform resin causes problems such as separation during curing and a reduction in stress relaxation effect.

In the present invention, as the epoxy resin to be reacted with the dimethylpolysiloxane having a hydroxyphenyl group at both ends represented by the above general formula (1), bisphenol F containing a mononuclear compound as a main component is used from the following viewpoints. Type epoxy resins are preferred. In other words, they do not increase the crosslink density, maintain a low elastic modulus, react at a low temperature, suppress the viscosity of the reaction product to a low level, and have mutual melting properties with epoxy resins and silicones having a low viscosity at room temperature.

The bisphenol F type epoxy resin can be generally synthesized by a reaction between bisphenol F and epichlorohydrin. This bisphenol F type epoxy resin may be multimerized at the stage of synthesis, such as dimerization or trimerization. However, the mononuclear bisphenol F epoxy resin used in the present invention refers to a mononuclear bisphenol F type epoxy resin having a low content of such a multimeric epoxy resin.

Further, it is preferable that the mononuclear body of the bisphenol F type epoxy resin is purified by distillation to reduce the content of the multimer.

Examples of the bisphenol F type epoxy resin having a mononuclear body as a main component include, for example, EX manufactured by Dainippon Ink Co., Ltd.
A-830 LVP and the like.

As a method for reacting a dimethylpolysiloxane having a hydroxyphenyl group at both terminals represented by the general formula (1) with an epoxy resin, the two components are mixed with a catalyst, and the mixture is heated and stirred under drying. be able to.

At this time, in the reaction for obtaining the epoxy-modified silicone compound, the mixing ratio of the dimethylpolysiloxane having a hydroxyphenyl group at both terminals and the epoxy resin is determined by the following reason. It is desirable that the epoxy equivalent of the epoxy resin be 1.5 to 2 times the equivalent. In other words, controlling the reaction system, it becomes a homogeneous solution in a short time,
The epoxy resin reacts and adds to both ends of dimethylsiloxane, the resin is cured, and the cured resin retains a low elastic modulus.

As the reaction catalyst, conventional catalysts may be used, for example, phosphines such as triphenylphosphine and tricyclohexylphosphine, and the like.
Examples thereof include imidazoles such as -methylimidazole and 2-ethyl-4-methylimidazole. Triphenylphosphine is preferably used from the viewpoint of good dispersibility and uniform reaction. The amount of the catalyst was 0.1 to 100 parts by weight of the epoxy resin.
The amount is preferably 20 to 20 parts by weight, and more preferably 1 part by weight or less from the viewpoint of an appropriate reaction rate, heat generation and uniformity of the reaction.

The reaction temperature is 100 to 130 ° C., and when the reaction is completed, the mixed solution becomes colorless and transparent,
It can be confirmed by measuring the molecular weight of the reactant.

The epoxy-modified silicone compound thus obtained is liquid at room temperature and has a viscosity of 2000-5.
The reaction is completed in the range of 000 cps (25 ° C./10 rpm), and preferably in the range of 3000 to 4000 cps. The weight average molecular weight of the reactant is 12000 to 2
6000 range, and 16000-2200
It is preferably in the range of 0. When used as the composition of the present invention, it can be handled in the same manner as a general epoxy resin.

Next, as the curing agent used in the present invention, diallyl bisphenol F is used because it has a function of imparting adhesiveness in addition to the function as a curing agent and has a low viscosity. Further, it needs to be used in combination with dicyandiamide as it cures in a three-dimensional crosslinked network structure and has good dispersibility and has potential.

The amount of diallyl bisphenol F used is preferably 65 to 90% by weight in the mixture of diallyl bisphenol F and dicyandiamide from the viewpoint of lowering the viscosity of the resin paste and imparting adhesiveness. , 75-8
More preferably, it is 0% by weight.

The amount of the curing agent (B) used for obtaining the conductive adhesive of the present invention may be 1 to 20 parts by weight based on 100 parts by weight of the epoxy compound modified at both ends with epoxy (A). The OH equivalent is 0 with respect to 1 equivalent of the epoxy equivalent of the epoxy resin in terms of uniform reaction and adhesion, and prevention of unreacted substances outgassing after the curing of the adhesive to contaminate the element. It is particularly preferred that the amount is from 0.5 to 1.0 equivalent.

As the curing accelerator (C) used in the present invention, an imidazole-based curing accelerator is used from the viewpoint of controlling the reaction rate, having the potential, and maintaining the long-term storage stability of the resin. Are preferred, especially having a high melting point,
From the viewpoint of good dispersibility, it is preferable to use finely pulverized 2-phenyl-4-methyl-5-hydroxymethylimidazole.

The amount of the curing accelerator (C) used is in the range of 1 to 5 parts by weight based on 100 parts by weight of the epoxy compound modified at both ends with the point that the reaction rate is controlled and unreacted components do not remain. It is particularly preferred that they be added.

The conductive filler (D) used in the present invention may be any one as long as it has been conventionally used for a conductive adhesive, such as a conductive metal such as gold, silver, copper, or nickel; Examples thereof include those obtained by coating the surface of an insulator such as fine powder of Bon Black, alumina, or glass with a conductive metal. Among them, gold, silver, copper, and iron are preferably used from the viewpoint of obtaining high conductivity.
It is particularly preferable to use silver because it is not easily oxidized, is inexpensive, and is easy to shape.

The shape of these conductive fillers is arbitrary, and flakes, spheres, dendrites, fibers, and the like are used. However, flakes are preferable because they can be highly filled and have high conductivity. Preferably, one is used. Also,
A mixture of spherical particles may be used in order to increase the filling for giving higher conductivity and to adjust the viscosity and thixotropy of the resin paste.

The particle size of the flakes may be in the range of those conventionally used for conductive adhesives, for example, 0.1 to 100 μm.
It is preferable because it has low viscosity and good fluidity as the conductive adhesive. Further, from the viewpoint of workability and the like, and from the viewpoint of controlling the thickness of the adhesive layer, the maximum particle size is 30 μm, and the average particle size is 3 to 1
It is preferable to use one having a thickness of 0 μm.

When the spherical filler is mixed, the average particle size is preferably 0.1 to 5 μm.

Mixing ratio of flake and spherical (weight ratio)
Is preferably spherical 3 to 0 with respect to flakes 7 to 10.

The conductive filler is well compatible with both ends epoxy-modified dimethylsiloxane, which is a matrix resin, and diallyl bisphenol F, dicyandiamide, imidazole curing catalyst, and the like, and has an adhesive force with the matrix resin even after heat treatment. Further, in order to keep the viscosity of the conductive adhesive low, it is preferable that the surface is treated with a material similar to the matrix resin, and it is particularly preferable that the surface of silver is treated with a small amount of a silicone compound.

The amount of the conductive filler (D) used is preferably an epoxy at both ends in view of high filling for imparting high conductivity and improving the workability by adjusting the viscosity and thixotropy of the resin paste. Modified silicone compound (A) 100
It is preferably from 350 to 530 parts by weight, more preferably from 400 to 470 parts by weight, based on parts by weight.

The method for producing the conductive adhesive of the present invention may be any conventional method. For example, the epoxy-modified silicone compound (A), the curing agent (B) and the curing accelerator (C) may be used. A method is used in which a predetermined amount is weighed and preliminarily mixed with a raikai machine, then a predetermined amount of the conductive filler (D) is mixed with the raikai machine, and finally kneaded with a three roll or kneader.

The conductive adhesive of the present invention obtained as described above has a high adhesive strength to an adherend and is excellent in a thermal stress relaxing effect. In addition, since it does not easily decompose or separate during storage, it has excellent long-term storage stability. Furthermore, since it has a low viscosity, there is no need to use a reactive diluent or solvent for adjusting the viscosity, and there is no generation of voids or outgas during curing. Moreover, since it has a thixotropic property, it is excellent in workability. Therefore, using the conductive adhesive of the present invention, Ga
Adhesion of semiconductor elements such as As chips, DRAM, CSP, etc. or semiconductor modules mounted with transistors, diodes, etc. to supporting members such as iron / nickel frame, copper frame, glass epoxy board, ceramic board, etc. A semiconductor device having excellent properties and electrical conductivity can be obtained.

FIGS. 1 to 3 show schematic sectional views of the semiconductor device of the present invention, but the present invention is not limited to these. In FIG. 1, 1 is a conductive adhesive, 2 is a copper frame, 3 is Ga
This is an As chip. In FIG. 2, 4 is a glass epoxy substrate, 5 is a silicon chip, and 6 is a sealing material.
Any conventional sealing material may be used. In FIG. 3, 7 is an aluminum substrate, and 8 is an alumina substrate.

Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to only these.

[0051]

EXAMPLES Table 1 shows each component used in the examples.

[0052]

[Table 1]

Production Examples 1 to 11 (Production of Epoxy-Modified Silicone Compounds at Both Ends (A-1) to (A-11)) In a 500 ml separable flask equipped with a stirrer and a thermometer, both components were mixed in the proportions shown in Table 2. A dimethylpolysiloxane having a hydroxyphenyl group at a terminal and an epoxy resin were put therein, stirred, heated to 120 ° C. while flowing dry nitrogen or dry air, and stirred and mixed for 2 hours as it was.

[0054]

[Table 2]

Next, 1 part by weight of triphenylphosphine was added as a catalyst to 100 parts by weight of the epoxy resin. An exotherm occurred immediately after the catalyst addition and the color of the solution turned orange. The viscosity was measured using an E-type viscometer, and when the target viscosity was reached, the completion of the reaction was confirmed. The obtained reaction product was cooled (air-cooled) to obtain a double-ended epoxy-modified silicone compound (A) according to the present invention. -1) to (A-11) were obtained.

Examples 1 to 6 Using the double-ended epoxy-modified silicone compounds (A-1) to (A-6) obtained in Production Examples 1 to 6 at the compounding ratio (% by weight) shown in Table 3, the curing agent ( B) and the curing accelerator (C) were added, and the mixture was kneaded for about 1 hour with a raikai machine to obtain a silicone-modified epoxy resin composition to be a matrix resin.

The conductive filler (D) was added to the obtained silicone-modified epoxy resin composition in the mixing ratio shown in Table 3, and the mixture was kneaded for about 1 hour with a raikai machine, and further kneaded 3 to 5 times with a three-roll mill. Finally, vacuum degassing was performed to obtain the conductive adhesive of the present invention.

Example 1 has a molecular weight of phenol dimethylpolysiloxane at both ends of 2,000 and an OH equivalent of 1189, Example 2 has a molecular weight of phenol dimethylpolysiloxane of both ends of 4500 and an OH equivalent of 1980, and Example 3 has a phenol at both ends of phenol. Dimethylpolysiloxane having a molecular weight of 7,000 and an OH equivalent of 2240. In Example 4, the molecular weight of the phenol dimethylpolysiloxane at both ends was 1000.
0, OH equivalent of 4000, Example 5 has a molecular weight of phenol dimethylpolysiloxane at both ends of 4500, and the amount of residual impurities is 10% by weight or less. Example 6 has a molecular weight of phenol dimethylpolysiloxane of both ends of 7,000.
Those having an impurity residual amount of 10% by weight or less were used.

Comparative Examples 1 to 10 Both ends epoxy-modified silicone compounds (A-6), (A-7), (A-8) and (A-
9) Using (A-10) and (A-11), a curing agent (B) and a curing accelerator (C) were added at the compounding ratio shown in Table 3, and kneaded for about 1 hour with a raikai machine. A silicone-modified epoxy resin composition serving as a matrix resin was obtained.

[0060]

[Table 3]

The conductive filler (D) was added to the obtained silicone-modified epoxy resin composition at the compounding ratio shown in Table 3, kneaded for about 1 hour with a raikai machine, and further kneaded three times with a three-roll mill. Finally, vacuum degassing was performed to obtain a conductive adhesive of Comparative Example.

Comparative Example 1 uses a phenol dimethylpolysiloxane having a molecular weight of 500 at both ends and an OH equivalent of 230. Comparative Example 2 uses a phenol dimethylpolysiloxane having a molecular weight of 12000 and an OH equivalent of 4800. Comparative Example 3 has a molecular weight of 4,500 at both ends of phenol dimethyl polysiloxane and a residual amount of impurities of 10% by weight.
In Comparative Example 4 using the following, the molecular weight of phenol dimethylsiloxane at both ends was 7,000 and the residual amount of impurities was 10
% Or less, Comparative Example 5 used bisphenol A for synthesizing the epoxy compound modified at both ends, Comparative Example 6 used a phenol novolak resin as a curing agent, and Comparative Example 7 used a curing agent as a curing agent. Comparative Example 8 using only diallyl bisphenol F as a curing agent, Comparative Example 9 using 2E4 as a curing accelerator
Comparative Example 10 using Mz does not use a curing accelerator.

The following evaluation was carried out on the epoxy compound modified at both ends, the matrix resin (silicone-modified epoxy resin composition) and the obtained conductive adhesive used for producing the conductive adhesive. Table 2 shows the results
And Table 3.

[Evaluation Method] Viscosity of Epoxy-Modified Silicone Compounds at Both Terminals The viscosity values of the epoxy-modified silicone compounds at both ends (A-1) to (A-11) obtained in Production Examples 1 to 11 were measured by using a product of Tokyo Keiki Co., Ltd. Using an E-type viscometer, the measurement was performed at 25 rpm at a rotation speed of 10 rpm.

Molecular weight of epoxy-modified silicone compound at both ends The molecular weight of epoxy-modified silicone compound at both ends (A-1) to (A-11) obtained in Production Examples 1 to 11 was determined by using TOSO
It was measured by GPC (Gel permeation chromatography).

Mutual Meltability of Both Terminal Epoxy-Modified Silicone Compounds Both terminal epoxy-modified silicone compounds (A-1) to (A-11) obtained in Production Examples 1 to 11 are allowed to stand at room temperature for one day. The transparency (white turbidity) from the end of the reaction, and standing at room temperature for one day to visually observe whether it has separated into two or three layers. Transparent to translucent was rated as ○, and completely turbid or separated was rated as x.

Curability of Matrix Resin (Silicone-Modified Epoxy Resin Composition) Both ends epoxy-modified silicone compound (A), curing agent (B) and curing accelerator obtained in Examples 1 to 6 and Comparative Examples 1 to 10 The matrix resin (silicone-modified epoxy resin composition) obtained by kneading (C) was applied on a glass plate and stored in an oven at 125 ° C. for 2 hours. It was taken out and it was confirmed whether it was hardened or remained liquid.

Thermal Stress Relaxation Effect A semiconductor device having the structure shown in FIG. 3 was manufactured using the obtained conductive adhesive. A 2 mm × 2 mm GaAs chip was bonded to a 20 mm × 40 mm alumina substrate by heating the alumina substrate to an aluminum substrate at 125 ° C. for 2 hours to obtain a test piece for evaluating a thermal stress relaxation effect.

The test piece was subjected to 100 heat cycles of holding at -30 ° C. and 60 ° C. for 30 minutes each, and the state of peeling of the bonded portion was confirmed by an ultrasonic flaw detector.
s: When there is no peeling or cracking between the chip and the alumina substrate and between the alumina substrate and the aluminum base, ◎ indicates that there is slight peeling, but there is slight peeling, but 問題 indicates that there is no practical problem. And a case where there was a problem in practical use was evaluated as x.

Adhesive Strength A 2 mm square silicon chip was placed on a nickel-plated aluminum plate using the obtained conductive adhesive at 125 ° C.
For 2 hours. The adhesive strength was measured at room temperature using a push-pull gauge.

Storage stability The presence or absence of an increase in the viscosity of the conductive adhesive was determined using an E-type viscometer.
Every predetermined number of days, the measurement was conducted at 25 ° C. and 10 rpm.

[Evaluation Results] As can be seen from Table 3, in Examples 1 to 6, the weight average molecular weight Mw was from 2000 to 100.
A resin composition obtained by mixing a double-end epoxy-modified silicone compound obtained by synthesizing a double-end phenol dimethylpolysiloxane with a bisphenol F epoxy resin, diallyl bisphenol F, dicyandiamide, and 2-ethyl-4-methyl-5-hydroxymethylimidazole. By using it, the stress relaxation effect is large, the adhesive strength is large,
A conductive adhesive having low resin viscosity, good workability, and excellent storage stability. In particular, the larger the molecular weight of the phenol dimethyl polysiloxane at both ends, the greater the stress relaxation effect. Further, when the residual amount of impurities of the phenol dimethyl siloxane at both ends is 10% by weight or less, the reaction between the impurities and the epoxy resin does not occur preferentially, so that the mutual melting property of the epoxy modified silicone at both ends is good. is there.

According to Comparative Example 1, the viscosity of the synthesized epoxy-modified silicone compound was high because the molecular weight of the phenol-dimethylpolysiloxane at both ends used for the synthesis of the epoxy-modified silicone compound at both ends was high, and therefore the viscosity of the conductive adhesive was high. And the workability is inferior. Also, the effect of relaxing thermal stress is small.

According to Comparative Example 2, since the molecular weight of the phenol dimethylpolysiloxane at both ends used for the synthesis of the epoxy-modified silicone compound at both ends is large, the mutual melting property with the epoxy resin is low and the synthesis reaction does not proceed. Therefore,
The phenol dimethyl polysiloxane at both ends is separated from the epoxy resin, only the epoxy resin reacts with the curing agent, and the dimethyl polysiloxane remains unreacted, resulting in poor curability and poor storage stability.

According to Comparative Example 3, in the synthesis of the epoxy compound modified with epoxy at both ends, the reaction was stopped halfway and the molecular weight was 12,000 or less. Therefore, a large amount of unreacted substances remained, and the curability of the matrix resin was poor. Also, the effect of relaxing thermal stress is low, and the adhesive strength is low.

According to Comparative Example 4, the reaction was continued for a long time in the synthesis of the silicone compound modified with epoxy at both ends.
Since it was used with a molecular weight of 26,000 or more, the viscosity of the matrix resin was increased, the workability was poor, and the adhesive strength was low.

According to Comparative Example 5, bisphenol A resin was used as the epoxy resin used for the synthesis of the epoxy compound modified with epoxy at both ends, so that the viscosity of the resin was increased. And storage stability is inferior.

According to Comparative Example 6, since a solid phenol novolak resin was used as a curing agent, the viscosity of the resin was high even when it was melted at a high temperature, and the resin did not become a homogeneous solution. Low relaxation effect and low adhesive strength.

According to Comparative Example 7, since diallyl bisphenol F was not used as the curing agent, the adhesiveness was poor.

According to Comparative Example 8, since dicyandiamide was not used as the curing agent, the curability was poor.

According to Comparative Example 9, liquid 2E was used as the curing accelerator.
Since 4Mz is used, it has no potential and has poor storage stability and poor thermal stress relaxation hardening.

According to Comparative Example 10, the resin was not cured because no curing accelerator was used.

[0083]

According to the conductive adhesive of the present invention, (A)
An epoxy-modified silicone compound having a molecular weight of 1200, which is obtained by reacting a dimethylpolysiloxane having a hydroxyphenyl group at both terminals represented by the general formula (1) with a mononuclear body of a bisphenol F type epoxy resin.
0-26000, (B) diallylbisphenol F and dicyandiamide, (C) 2-phenyl-4-
Since methyl-5-hydroxymethylimidazole and the conductive filler (D) are essential components, there is an effect of being excellent in thermal stress relaxation effect, workability, and long-term storage stability.

Further, according to the conductive adhesive of the present invention, in the dimethylpolysiloxane having hydroxyphenyl groups at both ends, the residual amount of impurities such as allylphenol and internal isomers as the current material is 10% by weight or less. Therefore, there is an effect that the uniformity of the reaction product with the bisphenol F type epoxy resin is excellent, and the curability, thermal stress relaxation property and storage stability of the matrix resin are excellent.

Further, according to the semiconductor device of the present invention, the semiconductor element or the semiconductor module and the supporting members such as the lead frame and the substrate are joined by using the conductive adhesive. There is an effect that the property is high.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of one embodiment of a semiconductor device of the present invention.

FIG. 2 is a schematic sectional view of another embodiment of the semiconductor device of the present invention.

FIG. 3 is a schematic sectional view of still another embodiment of the semiconductor device of the present invention.

[Explanation of symbols]

1 conductive adhesive, 2 copper frame, 3 GaAs chip, 4 glass epoxy board, 5 silicon chip,
6 sealing material, 7 aluminum base material, 8 alumina substrate.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hirofumi Fujioka 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Ryoji Shirahana 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Rishi Electric Co., Ltd. (72) Inventor Naoya Takimi 2-3-2 Marunouchi, Chiyoda-ku, Tokyo F-term (reference) 4J040 EC281 HA026 HA066 HB38 HC18 HC24 JB10 KA03 KA07 KA16 KA17 KA32 LA01 LA05 LA06 MB05 NA20

Claims (3)

[Claims] (A) General formula (1): (Wherein, R ¹ and R ² represent a divalent organic group having 1 to 20 carbon atoms, which may be the same or different,
n is an integer. Weight-average molecular weight Mw having a hydroxyphenyl group at both ends represented by
Is a two-terminal epoxy-modified silicone compound obtained by the reaction of dimethylpolysiloxane with a mononuclear body of a bisphenol F type epoxy resin, having a weight molecular weight Mw of 12,000 to
26000, (B) diallyl bisphenol F and dicyandiamide, (C) 2-phenyl-4-methyl-5-hydroxymethylimidazole, and (D)
A conductive adhesive containing a conductive filler as an essential component. 2. Dimethylpolysiloxane having a hydroxyphenyl group at both terminals and having a weight molecular weight Mw of 2,000 to 10,000 is characterized in that its raw materials, such as allylphenol and internal isomers, have a residual amount of impurities of 10% by weight or less. 2. The conductive adhesive according to claim 1, wherein: 3. A semiconductor device in which a semiconductor element or a semiconductor module and a supporting member such as a lead frame and a substrate are joined using the conductive adhesive according to claim 1.