JPH08199045A - Method for producing epoxy resin composition and semiconductor device using the resin composition - Google Patents

Abstract

(57) [Summary] [Structure] An alkoxysilane and water having a pH of 3.0 to 6.0 are added to an epoxy resin dissolved in an organic solvent, and the alkoxy group of the alkoxysilane is hydrolyzed to a silanol group in the presence of an acid catalyst. A method for producing an epoxy resin composition, characterized in that the solvent is removed after decomposition, and inorganic particles obtained by the subsequent heat treatment are filled. [Effect] The compounding amount of the filler can be increased without increasing the viscosity, and the inorganic filler can be compounded in an amount of 90 parts by weight or more of the resin component. Since the storage elastic modulus of the obtained resin composition is equal to or lower than that of the epoxy resin with no filler, the thermal stress generated during solder reflow and temperature cycle can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an epoxy resin composition containing an inorganic filler, and a resin-encapsulated semiconductor device encapsulated with the composition.

[0002]

2. Description of the Related Art In recent years, the degree of integration of semiconductor devices has improved year by year,
Along with this, the chip size is becoming larger, the wiring is becoming finer, and the number of layers is increasing. On the other hand, in order to increase the packaging density, it is essential to reduce the package size and make the package thinner, and accordingly, the package type resin layer is also becoming thinner. When the sealing resin becomes thin, cracks occur in the sealing resin and the passivation film due to the thermal stress caused by the difference in the coefficient of thermal expansion of the constituent materials, which causes a decrease in reliability. In order to reduce such thermal stress, it is general that the sealing resin is mixed with an inorganic filler to reduce the coefficient of thermal expansion of the resin. Such an inorganic filler is usually added by melting and kneading a pulverized product of fused silica or a spherical quartz powder obtained by heating and melting quartz powder to a melting point or higher with an epoxy resin using a mixing roll or the like. In the method, if the amount of the filler compounded is increased, the fluidity of the resin composition is lowered, so that the sealing work becomes difficult. As described in JP-A-63-128020, a method of increasing the compounding amount of a filler by using spherical fused silica powder having a specific particle size and particle size distribution has been proposed, but such an inorganic filler is used. The agent has an extremely high elastic modulus
(Fused silica: 7400 kgf / mm ² ) When the resin composition is highly filled, the elastic modulus of the obtained resin cured product increases. Generally, 70 to 80 parts by weight of filler is 1500 to 2500 kgf /
reach mm ² . Therefore, the effect of reducing the thermal expansion cannot be sufficiently exerted with respect to the generated thermal stress.

On the other hand, it is also effective to reduce the elastic modulus of the resin composition in the method of reducing the generated thermal stress. As a method for lowering the elastic modulus of this resin cured product, introduction of a softening agent such as a silicon compound has been studied. However, since the encapsulating material has an extremely high fraction of the filler having a high elastic modulus, even if the elastic modulus of the matrix resin is reduced, the effect of lowering the elastic modulus of the encapsulating material is not so remarkable, and the semiconductor material is not very significant. The device cannot achieve a dramatic reduction in thermal stress.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances and has been made to solve the above-mentioned problems, and an object thereof is to provide an epoxy resin for semiconductor encapsulation in which thermal stress generation is smaller. To obtain the composition with good workability, and
An object is to provide a highly reliable semiconductor device using a resin composition.

[0005]

The epoxy resin composition according to the present invention is manufactured by dissolving an epoxy resin, a curing agent and a curing accelerator in an organic solvent, adding an alkoxysilane and water adjusted to pH 3 to 6 thereto. A predetermined amount is added, and the mixture is stirred at room temperature for a predetermined time to hydrolyze the alkoxy groups into hydroxyl groups. After that, the solvent is removed under reduced pressure to obtain a resin powder. By subsequently heating the obtained resin powder, the resin is cured and the hydroxyl groups are dehydrated to obtain an epoxy resin composition in which the particles of the inorganic filler are uniformly dispersed in the resin. As the organic solvent used here, a good solvent for the epoxy resin such as acetone, N-methylpyrrolidone, or dimethylacetamide is selected. The amount of water to be added may be selected in the vicinity of the equivalent amount in the hydrolysis of alkoxysilane, for example. The reaction time at room temperature is selected so that the hydrolysis reaction proceeds sufficiently. As an example, it is about 3 to 10 hours.

According to this method, since all the constituent materials are mixed in the solution, the filler is uniformly dispersed, and it is possible to prevent the internal stress from being locally nonuniform due to the uneven distribution of the filler.
The particle size of the filler can be controlled to 10 μm or less by adjusting the acidity of water added during hydrolysis to pH 3 to 6. That is, if the pH is 3 or less, the particles agglomerate to hinder the uniform dispersion of the filler, and if the pH is 6 or more, the hydrolysis reaction is delayed, which is not practical. Further, according to this method, since the constituent materials are mixed in the solution, the blending amount of the filler can be increased without increasing the viscosity, and the inorganic filler is blended in an amount of 90 parts by weight or more of the resin component. It is possible.

Examples of the epoxy resin used in the present invention are:
Biphenyl type epoxy resin, cresol novolac type epoxy resin, phenol novolac type epoxy resin, bisphenol A type epoxy resin, etc. which are commonly used as molding materials for semiconductor encapsulation at present are used as a curing agent. A novolac resin having an acid, an acid anhydride such as pyromellitic dianhydride, benzophenone anhydride, and an amine compound are used, and if necessary, triphenylphosphine, imidazole or the like is added as a curing accelerator.

The alkoxysilane used in the present invention is represented by the general formula R ¹ _m Si (OR ² ) _n (m is 0 or 1, and n is 4-m), and R ¹ has ¹ to 10 carbon atoms. 6 is a saturated or unsaturated alkyl group, or a monovalent organic group having at least one amino group, epoxy group or vinyl group, and R ² is an alkyl group having 1 to 6 carbon atoms. Such alkoxysilanes include tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, ethyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ.
-Aminopropyltriethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltriethoxysilane and the like can be mentioned. Among these, especially γ having an epoxy group
-The resin composition produced by using glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane or the like has a cured product that is transparent and has excellent flexibility. It is presumed that this is because the epoxy group is present in the molecule of the alkoxysilane, so that the compatibility between the filler and the epoxy resin is improved and the filler is dispersed as very fine spherical particles.

Further, since the storage elastic modulus of the resin composition obtained by this method is equal to or lower than that of the epoxy resin with no filler added, a great reduction effect on the thermal stress in the semiconductor device can be achieved.

[0010]

As described above, the detailed expression mechanism in which the cured product obtained by the method for producing a resin composition according to the present invention exhibits low elasticity and low thermal expansion has not been clarified at present. One of the presumed reasons is that by using an alkoxysilane, which is an organic compound excellent in compatibility with an epoxy resin, as a filler introduction method for achieving low thermal expansion, the filler in the resulting cured product has a strong interaction with the epoxy matrix. It is considered that this is because the effect is exerted and the fine particles are uniformly dispersed, so that the bulk modulus of the cured product is less affected by the filler portion having an island structure, and the characteristics of the epoxy matrix are remarkably exhibited. It is important to investigate the cause of this phenomenon in the future.

[0011]

EXAMPLES The present invention will be specifically described below with reference to examples.

(Example 1) 13 g of biphenyl type epoxy resin YX4000 (product name of Yuka Shell Co., Ltd.), 7 g of phenol novolac resin (product name of Meiwa Kasei Co., Ltd.) and 0.2 g of triphenylphosphine in a 300 ml beaker.
Was dissolved in 100 g of acetone, and 34.3 g of methyltriethoxysilane was added. Add 1 pH of water to this resin solution.
69 g was added dropwise, and stirring was continued at room temperature for 3 hours to hydrolyze the alkoxysilane in the epoxy resin solution. The solvent and excess water were removed by vacuum drying to obtain a milky white resin powder. The obtained resin powder is melted on a hot plate at 130 ° C,
Subsequently, it was heated and cured at 200 ° C. for 2 hours under a pressure of 1 × 10 ⁷ N / m ² to obtain a white opaque resin plate having a SiO ₂ content of 70 ppm by weight. When the fracture surface of the obtained resin cured product is observed by a scanning electron microscope photograph, SiO ₂ particles having a particle diameter of 1 to 10 μm are uniformly dispersed, and the elastic modulus of the resin plate at room temperature is 240 kgf / mm ² Met.

(Examples 2 to 7) In the same manner as in Example 1 except that the kind and amount of alkoxysilane were changed.
A resin cured product was obtained. Table 1 shows the kinds and addition amounts of the alkoxysilanes used and various properties of the obtained cured products.

[0014]

[Table 1]

Comparative Example 1 13 g of the same biphenyl type epoxy resin as in Example 1 and 7 g of phenol novolac resin
And triphenylphosphine (0.2 g) were mixed and melted, and the pulverized resin powder was compressed to 200 at a pressure of 1 × 10 ⁷ N / m ^2.
A transparent resin plate was obtained by heating and curing at 2 ° C for 2 hours. The elastic modulus of this resin plate at room temperature was 250 kgf / mm ² .

(Comparative Example 2) Biphenyl type epoxy resin 2
To 60 g, 140 g of phenol novolac resin, and 4 g of triphenylphosphine, add 70 parts by weight of fused silica to 8
The mixture was kneaded with a mixing roll at 0 ° C. for 15 minutes and then molded by injection molding. The elastic modulus of this cured product is 2000 kgf /
It was mm ² .

[0017]

EFFECTS OF THE INVENTION According to the present invention, since inorganic particles are formed in a dendritic solution, the inorganic filler is easily and uniformly dispersed even if it is highly filled, and the internal stress is uneven due to the uneven distribution of the filler. Can be prevented. The particle size of the filler can be controlled to 10 μm or less by adjusting the acidity of water added during hydrolysis to pH 3 to 6. Further, according to this method, since the constituent materials are mixed in a uniform solution in which a precipitate does not occur, it is possible to prevent an increase in viscosity at the time of blending the filler. Therefore, it is possible to mix 90 parts by weight or more of the inorganic filler with the resin component. Further, since the elastic modulus of the obtained resin composition is equal to or lower than that of the epoxy resin without a filler, by using the epoxy resin composition obtained by the present invention as a sealing material, thermal stress can be reduced. It is possible to obtain a highly reliable semiconductor device in which

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masanori Segawa, 7-1, 1-1 Omika-cho, Hitachi-shi, Ibaraki Hitachi Ltd. Hitachi Research Laboratory (72) Inventor Masahiko Ogino 7, 1-chome, Omika-cho, Hitachi-shi, Ibaraki No. 1 Hitachi Ltd. Hitachi Research Laboratory

Claims (7)

[Claims] 1. An alkoxysilane and water having a pH of 3 to 6 are added to an epoxy resin dissolved in an organic solvent, the alkoxy group of the alkoxysilane is hydrolyzed to a silanol group in the presence of an acid catalyst, and then the solvent is removed. A method for producing an epoxy resin composition, which comprises filling the particles obtained by the heat treatment of 1. 2. A method for producing an epoxy resin composition, wherein the alkoxysilane according to claim 1 is an organotrialkoxysilane or an organotetraalkoxysilane. 3. A method for producing an epoxy resin composition, wherein the particles obtained by the method according to claim 1 are SiO ₂ particles having a particle size of 10 μm or less. 4. A method for producing an epoxy resin composition, wherein the resin has transparency, which is obtained by the method according to claim 1. 5. A resin cured product having a particle content of 50 parts by weight or more, which is obtained by the production method according to claim 1.
A method for producing an epoxy resin composition having a storage elastic modulus at room temperature of 1000 kgf / mm ² or less and a thermal expansion coefficient of 50 ppm / K or less. 6. A semiconductor device encapsulated with the epoxy resin composition according to claim 1. 7. An electronic device using a semiconductor device encapsulated with the epoxy resin composition according to claim 1.