JPH10158361A - Epoxy resin composition for sealing semiconductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition capable of improving the soldering resistance in surface mounting by compounding respectively specific epoxy resin, phenolic resin hardener, polysiloxane compound, inorganic filler and cure accelerator. SOLUTION: This composition contains (A) an epoxy resin containing 20-100wt.% (based on the total epoxy resin) of an epoxy compound of formula I (OG is a group of formula II; R1 is H, 1-6C chain or cyclic alkyl, etc.), (B) a phenolic resin hardener containing 20-100wt.% (based on the total phenolic resin hardener) of a phenolic resin hardener of formula III (0<=n<=4), (C) a polysiloxane compound of formula IV [0<=l<=30, 0<=m<=100, 1<=l+m<=130, 5<=l+m+n<=500; R1 is R2 or B; R2 is a 1-10C alkyl, etc.; A is R3 -COOH (R3 is a 1-9C organic group), etc.; B is R5 O-(C2 H4 O)a -(C3 H5 O)b -R6 (R5 is a 1-20C organic group; R6 is H, etc.; 0<=a<=300, 0<=b<=300, 0<a+b<=300), etc.], (D) an inorganic filler and (E) a cure accelerator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition for semiconductor encapsulation having excellent solder resistance and moldability in surface mounting of a semiconductor device.

[0002]

2. Description of the Related Art Conventionally, electronic parts such as diodes, transistors, and integrated circuits have been sealed by transfer molding of an epoxy resin composition suitable for low cost and mass production. As epoxy resin compositions for semiconductor encapsulation are blended with biphenyl type epoxy compounds having excellent heat resistance and moisture resistance, various phenol resin curing agents, fused silica, and inorganic fillers such as crystalline silica, (Referred to as a resin composition). As electronic devices have become smaller, lighter, and more sophisticated, semiconductors have become more highly integrated, and semiconductor packages have become larger, thinner, and surface-mounted. Are increasingly demanding.
For this reason, a problem that cannot be solved by the conventional resin composition has appeared. While the capacity of integrated circuits has increased and IC chips have become larger, packages have become thinner than before. That is, a large chip is encapsulated in a thin package, and abruptly increases in a solder reflow process.
Cracks occur due to thermal stress caused by exposure to a high temperature of 0 ° C. or more, and peeling occurs at each interface between a member constituting a package such as a chip and a lead frame and a sealing resin, resulting in remarkable reliability. There is a problem that it decreases.

[0003] In order to solve the reliability deterioration caused by the soldering, conventionally, a resin having a low melt viscosity is used and the filling amount of the fused silica powder is increased so that the resin composition at the time of molding has a low viscosity and a high resin composition. Generally, a method of achieving low moisture absorption and high strength while maintaining fluidity and improving solder resistance is common. Further, as a crystalline epoxy compound which is solid at normal temperature and extremely lowers in viscosity when melted, a biphenyl type epoxy compound is used as a typical example. Conventional crystalline epoxy compounds, particularly biphenyl type epoxy compounds, are used. Although the compound has the characteristic of low melt viscosity at the molding temperature, it has a limitation in fluidity, and furthermore, in the biphenyl structure that is its main skeleton, there is also a limit of the number of functional groups of two functions, and the strength at heat, glass It has also been pointed out that the cured product properties such as the transition temperature are low. In addition, with the increase in thin packages such as TSOP and TQFP, the thickness of the resin composition occupying in the package has become thinner. It is important that there is little deformation and there is no chip shift and die pad shift, and therefore, it is necessary to have excellent fluidity during molding. It is also particularly important that no bubbles remain (hereinafter, referred to as voids) in the package after molding.

[0004]

SUMMARY OF THE INVENTION The present invention is to improve the adhesion between a sealing resin and a member such as a chip and a lead frame, thereby significantly improving the solder resistance at the time of surface mounting. Good fillability with less deformation of gold wire, chip shift, die pad shift, etc., that is, it has the feature of high fluidity at the time of molding. An object of the present invention is to provide an epoxy resin composition for encapsulating a semiconductor having good cured product characteristics.

[0005]

The present invention provides (A) an epoxy resin containing the epoxy compound represented by the general formula (1) in an amount of 20 to 100% by weight in a total epoxy resin, and (B) an epoxy resin represented by the general formula (2). A phenolic resin curing agent containing 20 to 100% by weight of the phenolic resin curing agent shown in the total phenolic resin curing agent, (C) a polysiloxane compound represented by the general formula (3), (D) an inorganic filler, and (E) A) a phenolic resin comprising a curing accelerator, preferably used in combination with a phenolic resin curing agent represented by the general formula (2);
The epoxy resin composition for semiconductor encapsulation which is a xylylene-modified phenol resin represented by the formula:

Embedded image (R ₁ in the formula is hydrogen, a chain or cyclic alkyl group having 1 to 6 carbon atoms, a phenyl group, a group selected from halogen, or an atom. May be.)

[0006]

Embedded image (In the formula, 0 ≦ n ≦ 4.)

[0007]

Embedded image

[0008]

Embedded image (Where m ≧ 0, n ≧ 0, 1 ≦ m + n ≦ 10)

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the epoxy resin referred to in the present invention, a monomer having two or more epoxy groups in a molecule,
Including oligomers and polymers in general. The epoxy compound of the general formula (1) used in the present invention is usually called a stilbene structure type epoxy, and many studies have been already made and many reports have been published. This structure has a rigid planar or rod-like structure, and is a typical structure of a liquid crystalline polymer in which molecules are easily aligned. The resin composition using the epoxy compound having this structure, after curing, has a high strength at the time of heat derived from the rigid molecular skeleton of the epoxy compound and the orientation of the molecules, and has a low hygroscopic property, and thus has excellent solder resistance. There are features. Further, since the molecules are easily oriented by the shear stress, the fluidity of the resin composition is high even in low-pressure transfer molding, and the filling property in a thin package is excellent. Specific examples of the epoxy compound represented by the general formula (1) include, but are not limited to, the following formulas (5) to (7).

Embedded image

The proportion of the epoxy compound of the general formula (1) used in the present invention is 20 to 10 in the total epoxy resin.
0% by weight is desirable. If the content is less than 20% by weight, the high flow property at the time of molding, which is a characteristic of this crystalline epoxy compound, is not exhibited. The epoxy resin that can be used in combination with the epoxy compound of the general formula (1) refers to all monomers, oligomers, and polymers having an epoxy group, such as bisphenol A epoxy resin, orthocresol novolac epoxy resin, naphthalene epoxy resin, Triphenol methane type epoxy resin, epoxidized resin of dicyclopentadiene-modified phenols, and the like.In particular, in order to obtain a resin composition having excellent solder resistance, biphenyl diglycidyl ether, tetramethyl biphenyl diglycidyl ether, Epoxy compounds that exhibit crystallinity even at room temperature, such as hydroquinone diglycidyl ether and tetramethylbisphenol F diglycidyl ether, are preferred. When used in combination with the epoxy compound of the general formula (1), these epoxy resins may be used alone or as a mixture.

[0011] The phenolic resin curing agent of the general formula (2) used in the present invention is a flexible phenolic resin curing agent, which can absorb the stress at the time of heating and can be processed by soldering as compared with a phenol novolak resin curing agent. A decrease in the elastic modulus near the temperature, an improvement in the adhesion to the IC components such as the lead frame and the semiconductor chip, and a high crosslinking density can prevent a decrease in the glass transition temperature. Therefore, it is effective in preventing a reduction in stress generated in the soldering process and the accompanying peeling of a semiconductor chip or the like. The use ratio of the phenolic resin curing agent of the general formula (2) is 2% in the total phenolic resin curing agent.
The content is preferably 0 to 100% by weight, and if it is less than 20% by weight, adhesion to a semiconductor chip or the like becomes insufficient, and solder resistance does not improve. Further, the value of n in the formula is preferably from 0 to 4.
When the value of n exceeds 4, the fluidity during transfer molding is reduced, the moldability is reduced, and especially in the case of a thin package, the filling property is reduced.

Examples of the phenolic resin curing agent which can be used in combination with the phenolic resin curing agent of the general formula (2) include monomers and oligomers having a phenolic hydroxyl group and capable of undergoing a curing reaction with an epoxy resin to form a crosslinked structure. Refers to all polymers, for example, phenol novolak resin, cresol novolak resin, dicyclopentadiene-modified phenol resin, xylylene-modified phenol resin, terpene-modified phenol resin, bisphenol A, triphenolmethane, and the like, but are not limited thereto. is not. In particular, a xylylene-modified phenolic resin represented by the general formula (4) is suitable as a phenolic resin curing agent having an effect on the solder resistance of the resin composition. The xylylene-modified phenol resin of the general formula (4) is usually phenol and p-xylylene glycol dimethyl ether,
Alternatively, it is synthesized by a polycondensation reaction with m-xylylene glycol dimethyl ether. The xylylene-modified phenolic resin of the general formula (4) has low hygroscopicity, low modulus of elasticity when heated, and high adhesion to components such as lead frames, chips, etc., so that the absorbed moisture is vaporized by soldering. The effect of reducing the stress generated during the process and preventing the occurrence of package cracks is great. Further, as the ratio of the m-xylylene skeleton to the p-xylylene skeleton in the structure of the general formula (4) increases, the resin composition has a feature that the strength at heat is improved, and the resin composition tends to have more excellent solder resistance. . Also, m
When + n exceeds 10, the viscosity at the time of molding the resin composition increases, and the filling property is poor.

The polysiloxane compound used in the present invention is a component having particularly excellent effects in combination with the epoxy compound represented by the general formula (1). The epoxy compound represented by the general formula (1) is characterized by high fluidity due to its high orientation, high strength upon curing after curing, and low moisture absorption. However, due to the high degree of orientation, even in a resin composition heat-kneaded with other components, there is a strong tendency to easily partially crystallize and become non-uniform. This partial crystallization occurs during the cooling step after heat kneading and during storage at a low temperature, and cannot be prevented merely by heat kneading with other components at a temperature higher than the melting point of the crystal. The crystallized portion readily melts at the molding temperature to form a non-uniform liquid epoxy domain. For this reason, voids are generated due to rapid volume changes, or unreacted epoxy compound components are likely to become burrs during molding,
This causes a reduction in formability. As a means for preventing these, a method of adding a polysiloxane compound in a state where the epoxy compound is molten is effective. This is because part of the polysiloxane compound is compatible with the epoxy compound,
Another part is because it has a surface active action that makes it incompatible. This polysiloxane component is considered to have an effect of improving the affinity between the epoxy compound and a resin component other than the epoxy compound or an inorganic filler, and inhibiting crystallization of the epoxy compound.

The main skeleton of the polysiloxane compound, Si
Although the —O—Si bond is not compatible with the epoxy compound, the polyether bond or the polycaprolactone bond and / or the organic group in the formula (3) has compatibility with the epoxy compound. The polymerization degree (l + m + n) of the polysiloxane compound of the formula (3) is preferably from 5 to 500, and if it is less than 5, the compatibility with the epoxy compound is too large.
The surfactant effect is not obtained, the affinity with the inorganic filler is not improved, and the heat resistance is lowered. On the other hand, if it exceeds 500, the compatibility will be poor, and it will bleed out at the time of molding, causing mold contamination. Becomes Further, the number (l) of the organic functional group units in the polysiloxane compound of the formula (3) is preferably 30 or less, and if it exceeds 30, the fluidity during molding of the resin composition decreases. As the organic functional group, a glycidyl group,
Examples thereof include a cyclohexene oxide group, a carboxyl group, and an amino group. The number (m) of the polyether bond or polycaprolactone bond unit in the polysiloxane compound of the formula (3) is preferably 100 or less.
It causes a decrease in moisture resistance. (L + m) is preferably from 1 to 130 for the above reason. Further, the repeating unit (a + b) of polyether and the repeating unit (c) of polycaprolactone are preferably 300 or less. If it exceeds 300, the viscosity rises remarkably, and the moldability is lowered, and the moisture resistance is also lowered.

[0015] The curing accelerator used in the present invention includes:
Any material that promotes a curing reaction between an epoxy group and a hydroxyl group may be used, and those generally used for a sealing material can be widely used. Examples thereof include amidine compounds such as 1,8-diazabicyclo (5,4,0) undecene-7, triphenylphosphine, tetraphenylphosphonium / tetraphenylborate, dimethylbenzylamine, 2-methylimidazole, and the like. These may be used alone or as a mixture.

Examples of the inorganic filler used in the present invention include fused silica powder, spherical silica powder, crystalline silica powder, secondary aggregated silica powder, porous silica powder, and alumina. Mixtures of silica powder and spherical silica powder are preferred. The amount is preferably from 70 to 92% by weight in the total resin composition in order to obtain good moldability and solder resistance. If the content is less than 70% by weight, low thermal expansion and low moisture absorption cannot be obtained, and solder resistance becomes insufficient. If the content exceeds 92% by weight, the fluidity during molding is reduced due to the increase in viscosity, and disadvantages such as die pad shift, chip shift, and misalignment of the gold wire in the semiconductor package occur.

[0017] The resin composition of the present invention comprises, in addition to the components (A) to (E), if necessary, a silane coupling agent, a brominated epoxy resin, a flame retardant such as antimony oxide, hexabromobenzene, and carbon black. , Colorants such as bengalara,
Various additives such as release agents such as natural wax and synthetic wax, and low stress additives such as silicone oil and rubber may be appropriately compounded.

Further, the resin composition of the present invention comprises (A)
The (E) component and various additives are uniformly mixed using a mixer or the like, then melt-kneaded with a hot roll or a kneader, cooled, and pulverized to obtain a molding material.

Hereinafter, the present invention will be described specifically with reference to Examples.

【Example】

 Example 1 An epoxy compound represented by the formula (6) (melting point: 124 ° C.) 4.57 parts by weight A phenol resin represented by the formula (2) (softening point: 120 ° C., hydroxyl equivalent: 170 g / eq. The weight ratio of n = 0 to 1 is 1.4, n = 1 is 0.4, n = 2 is 0.4, and n = 3 is 0.1. (Referred to as (2-1)) 3.93 parts by weight 0.50 parts by weight of polysiloxane compound represented by formula (8)

Embedded image

Spherical fused silica 88.00 parts by weight Triphenylphosphine 0.20 parts by weight γ-glycidoxypropyltrimethoxysilane 0.50 parts by weight Brominated bisphenol A type epoxy resin 0.50 parts by weight Antimony trioxide After mixing with 00 parts by weight carbon black 0.30 parts by weight carnauba wax 0.50 parts by weight with a mixer, the mixture was kneaded at 100 ° C. using a biaxial roll, cooled and pulverized to obtain a resin composition. The properties of the obtained resin composition were evaluated by the following methods. Table 1 shows the results
Shown in

Evaluation method Spiral flow: Using a mold for measuring spiral flow according to EMMI-I-66, using a mold temperature of 175 ° C.
The measurement was performed at an injection pressure of 70 kg / cm ² and a curing time of 2 minutes. Gold wire deformation: 100-pin TQFP package (package size, 14 x 14 mm, thickness 1.4 mm, chip size 8.0 x 8.0 mm, lead frame is iron / nickel alloy (42 alloy), between chip and inner lead) Is bonded to a 5 mm long 25 μmφ gold wire)
Was subjected to transfer molding at a mold temperature of 175 ° C. and an injection pressure of 75 kg / cm ² for 2 minutes, and observed with a soft X-ray fluoroscope, and the deformation rate of the gold wire ((flow amount) / (gold wire length) × 100)
Was expressed in%. Void: The number of voids present in a 100-pin TQFP package formed by gold wire deformation evaluation was observed using an ultrasonic flaw detector. It is indicated by the number of voids in one package. Solder resistance: The 100-pin TQFP package used for the gold wire deformation was post-cured at 175 ° C. for 8 hours. The molded product package was left in an environment of 85 ° C. and a relative humidity of 85% for 168 hours, and then treated with an IR reflow device at 220 ° C. for 10 seconds, and this reflow treatment was repeated three times. The number of cracks in the package (the number of crack-occurring packages) / (the total number of packages) was displayed as the solder resistance on the ultrasonic flaw detection imaging apparatus. Heat strength: According to the test conditions of JIS-K6911, 24
The flexural strength at 0 ° C. was measured. Solder moisture resistance: A 100-pin TQFP package on which a test chip is mounted is molded in the same manner as the evaluation of gold wire deformation.
Post-cured at 175 ° C. for 8 hours. 8 molded product packages
It was left for 168 hours in an environment of 5 ° C. and a relative humidity of 85%, and then treated with an IR reflow device at 240 ° C. for 10 seconds, followed by PCT treatment (125 ° C., 2.4 kg / cm ² ).
The open failure of the circuit was measured and indicated by the failure occurrence time.

Example 2 A xylylene-modified phenolic resin represented by the formula (4) (provided that m / n = 3/1 by weight, m + n is 1 or more, and the proportion of components in which m + n ≧ 6 is present) Is 40% by weight and the hydroxyl equivalent is 170 g / eq.
1) was mixed and kneaded in the same manner as in Example 1 in accordance with the formulation shown in Table 1 to obtain a resin composition. Evaluation was performed in the same manner as in Example 1. Table 1 shows the results.

Examples 3 to 6, Comparative Examples 1 to 5 According to the formulations shown in Tables 1 and 2, mixing and kneading were carried out in the same manner as in Example 1 to obtain a resin composition. Evaluation was performed in the same manner as in Example 1. The results are shown in Tables 1 and 2. Table 1 and Table 2
Polysiloxane compounds represented by the following formulas (Formula (9) and Formula (10))
Is shown below.

Embedded image

[0024]

Embedded image

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

The resin composition of the present invention significantly improves the soldering resistance at the time of surface mounting by improving the adhesiveness to members such as chips and lead frames, and also has curability and fluidity. Has good moldability and is free of voids, and is particularly suitable for thin packages.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 23/31

Claims (2)

[Claims] 1. An epoxy resin containing the epoxy compound represented by the general formula (1) in an amount of 20 to 100% by weight in the total epoxy resin, and (B) a phenol resin curing agent represented by the general formula (2) in total. 20-100 in phenolic resin curing agent
Phenol resin curing agent containing by weight%, (C) general formula (3)
An epoxy resin composition for semiconductor encapsulation comprising: a polysiloxane compound represented by the formula: (D), an inorganic filler, and (E) a curing accelerator. Embedded image (R ₁ in the formula is hydrogen, a chain or cyclic alkyl group having 1 to 6 carbon atoms, a phenyl group, a group selected from halogen, or an atom. May be used.) (In the formula, 0 ≦ n ≦ 4.) 2. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the phenol resin used in combination with the phenol resin curing agent represented by the general formula (2) is a xylylene-modified phenol resin represented by the general formula (4). Stuff. Embedded image (Where m ≧ 0, n ≧ 0, 1 ≦ m + n ≦ 10)