JPH09316305A - Epoxy resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an epoxy resin composition reduced in void formation inside and outside and having excellent soldering cracking resistance by compounding an epoxy resin, a phenolic resin hardener, a curing accelerator, an inorganic filler, and a specific silicone oil. SOLUTION: The composition comprises an epoxy resin, a phenolic resin hardener, a curing accelerator, an inorganic filler, and a silicone oil represented by the formula I. In the formula, X is represented by the formula II; R1 is -CH3 or -OH; (m+n+2), which is the degree of polymerization N, is 3<=(m+n+2)<=250, provided that n>=1; and a, b, and c, which are the degrees of polymerization of the respective structural units, satisfy a+b>=2 and c>=2. The amount of the oil is preferably 0.02-3.0wt.% based on the whole composition. If the amount thereof is smaller than 0.02wt.%, no effect of the oil can be produced. If the amount thereof exceeds 3.0wt.%, dissolution of the oil in the epoxy resin is insufficient and part of the oil bleeds out. The bleeding reduces the adhesion of a molding to lead frames and reduces soldering cracking resistance.

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 which has few internal and external voids and is excellent in solder crack resistance and moisture resistance reliability.

[0002]

2. Description of the Related Art Epoxy resin-based resin compositions for semiconductor encapsulation have been developed and manufactured to protect IC bodies from mechanical and chemical actions. In order to satisfy the characteristics required for ICs, various performances are required for semiconductor encapsulating epoxy resin compositions (hereinafter referred to as resin compositions). A recent requirement is to improve solder crack resistance.
In order to improve the solder crack resistance, it is necessary to reduce the water absorption of the sealing resin, but for that purpose, it is necessary to increase the compounding amount of the inorganic filler more than ever. If the amount is too large, it cannot be uniformly dispersed in the resin composition, and voids frequently occur during molding. In order to reduce the generation of voids, various proposals have been made, such as using a resin with high viscosity and changing the particle size distribution of the inorganic filler. One effective for reducing voids is a copolymer of polyethylene oxide and polypropylene oxide grafted onto a silicone chain, and an epoxy group bonded to the side chain (Japanese Patent Publication No.
No. 36,148), the voids are surely eliminated by the surface-active effect, but there is a drawback that the adhesiveness to various base materials is reduced and the solder crack resistance is significantly reduced. It is considered that the cause of the decrease in adhesiveness is the localization of silicone oil to various interfaces. In addition, since this silicone oil lacks solubility at a molecular level in epoxy resin, even if it looks as if it was uniformly dispersed, the silicone oil is actually localized at various interfaces, and the silicone oil does not easily react with various base materials. The adhesion at the interface tends to decrease, and the solder crack resistance tends to decrease.

[0003]

DISCLOSURE OF THE INVENTION In the present invention, as a result of intensive studies to solve the above-mentioned drawbacks, when the resin in the flow is non-uniform, the flow front becomes very non-uniform and It is intended to provide an epoxy resin composition in which voids are easily formed and voids are transformed into voids, generation of internal and external voids is small, and solder crack resistance is excellent.

[0004]

The present invention provides an epoxy resin, a phenol resin curing agent, a curing accelerator, an inorganic filler,
And an epoxy resin composition comprising the silicone oil represented by the formula (1).

[0005]

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Each component will be described below. The epoxy resin used in the present invention is not particularly limited as long as it has two or more epoxy groups in the molecule, but preferred examples thereof include orthocresol novolac type epoxy resin, phenol novolac type epoxy resin, and bisphenol. Type epoxy resin, biphenyl type epoxy resin, stilbene type epoxy resin, triphenol methane type epoxy resin, alkyl modified triphenol methane type epoxy resin and the like, and these may be used alone or in combination. The epoxy equivalent and the softening point are not particularly limited.

The phenolic resin curing agent used in the present invention comprises:
It is not particularly limited as long as it has a hydroxyl group in the molecule, but preferable examples include, for example, phenol novolac resin, cresol novolac resin, dicyclopentadiene modified phenol resin, paraxylylene modified phenol resin, triphenol methane type phenol resin. , Terpene-modified phenolic resins, etc., and these may be used alone or in combination. Further, the hydroxyl equivalent, softening point, ortho / para ratio are not particularly limited. The curing accelerator used in the present invention may be any one as long as it accelerates the curing reaction between the epoxy group and the hydroxyl group, and those generally used in the encapsulating resin composition can be widely used. For example, 1,8-diazabicyclo (5,4,0) undecene-7, triphenylphosphine, tetraphenylphosphonium tetraphenylborate, benzyldimethylamine, 2-methylimidazole and the like can be mentioned, and these can be used alone or as a mixture. You can use it later.

Examples of the inorganic filler used in the present invention include fused silica powder, spherical silica powder, crystalline silica powder, secondary agglomerated silica powder, alumina and the like. From the viewpoint of improvement, spherical silica powder is desirable. As for the shape of the spherical silica powder, it is desirable that the shape of the particles themselves is infinitely spherical and the particle size distribution is broad in order to improve the fluidity. The amount of the inorganic filler added is not particularly limited.

The silicone oil of the formula (1) used in the present invention will be described in detail. The silicone oil of the formula (1) has a structure in which a main chain of a polydimethylsiloxane structure is grafted with a side chain containing polyether and alkyl. Of these, the silicone part and the alkyl part are hydrophobic groups, and the polyether is a hydrophilic group, and the silicone oil of the formula (1) has an amphipathic property, that is, a surfactant structure. That is, the present inventor has variously studied silicone oils suitable for reducing voids and improving solder crack resistance, and in order to uniformly disperse the inorganic filler and the epoxy resin for reducing voids, silicone oil is most suitable as a surfactant. It is necessary to properly design the ratio of hydrophilic groups and hydrophobic groups of silicone oil molecules, and to improve solder crack resistance, silicone oil is sufficiently compatible with epoxy resin even at the molecular level. It has been found that it is desirable that the silicone oil contains a large number of groups that are easily compatible with the epoxy resin. As a result, it was found that the silicone oil of the formula (1) is optimal for achieving both low void resistance and solder crack resistance. The silicone chain is completely incompatible with the epoxy resin, but the alkyl chain is slightly soluble. On the other hand, the polyether chains dissolve well. Like this
By introducing an alkyl chain whose solubility in the epoxy resin is between the silicone chain and the polyether chain, the solubility in the epoxy resin and the hydrophilic / hydrophobic balance can be freely changed. Furthermore, it is not necessary to introduce a functional group such as an epoxy group or an amino group, which is reactive with an epoxy resin, into the main chain of the silicone oil of the present invention, and localization at the interface does not occur.

The degree of polymerization N of the silicone main chain in the formula (1)
(= M + n + 2) is preferably 3 to 250. If the degree of polymerization is less than 3, there is a silicone oil that does not contain a polyether, which is a hydrophilic group, in one molecule at all, and since this silicone oil has no surface-active effect, voids increase. On the other hand, when the degree of polymerization exceeds 250, the viscosity of the silicone oil becomes high and it becomes difficult to dissolve it in the resin composition, and voids are similarly generated. n is preferably 1 or more. When n is less than 1, a silicone oil containing no hydrophilic polyether is present in one molecule, and since this silicone oil has no surface-active effect, voids increase. It is desirable that a + b be 2 or more. When a + b is less than 2, sufficient hydrophilicity cannot be obtained and the surfactant effect is lost, resulting in increased voids. c is preferably 2 or more. When c is less than 2, the structure is similar to a mere graft copolymer of silicone oil and polyether, and good characteristics of silicone oil are not exhibited. R ₁ is a methyl group or a hydroxyl group.

The amount of the silicone oil of the formula (1) to be added to the total resin composition is not particularly limited,
0.02-3.0% by weight is preferable. If it is less than 0.02% by weight, the effect of silicone oil will not be exhibited, and many voids will be generated as in the case of not adding. If it exceeds 3.0% by weight, it does not sufficiently dissolve in the epoxy resin and bleeds out, the adhesion of the molded product to the lead frame is reduced, and the solder crack resistance is reduced. The silicone oil of formula (1) may be used in combination with other types of silicone oil. However, if the other silicone oil used in combination exceeds 50% by weight of the total silicone oil, voids are generated and solder crack resistance is deteriorated, which is not preferable.

If necessary, the resin composition of the present invention contains a coloring agent such as carbon black, a brominated epoxy resin, a flame retardant such as antimony trioxide, and a coupling agent such as γ-glycidoxypropyltrimethoxysilane. It is also possible to add low stress components such as rubber. The resin composition of the present invention is an epoxy resin, a phenol resin curing agent, a curing accelerator, an inorganic filler, silicone oil, and other additives are mixed at room temperature with a mixer, and kneaded using a general kneader such as a roll or an extruder. Then, it can be cooled and pulverized to obtain a molding material.

The present invention will be specifically described below with reference to examples.
The mixing ratio is by weight. Example 1 Biphenyl type epoxy resin (YX400H (Okaka Shell Epoxy Co., Ltd., melting point 105 ° C., epoxy equivalent 195) 10.5 parts by weight Phenol novolac resin (H-1) 7.3 parts by weight Silicone oil (S-1 : Structure is shown in Table 4. 0.5 parts by weight Spherical silica (average particle size 15 μm) 80 parts by weight Carnauba wax 0.3 parts by weight Carbon black 0.2 parts by weight Brominated phenol novolac type epoxy resin (BrE) 0. 5 parts by weight Antimony trioxide 0.5 parts by weight Triphenylphosphine 0.2 parts by weight are mixed at room temperature in a mixer, kneaded at 100 ° C. using a biaxial roll, cooled, pulverized, and dried by dry air to obtain The obtained molding material was molded and evaluated for voids and solder crack resistance, and the evaluation results are shown in Table 1.

Evaluation method Evaluation of void: 160 pQFP (28 × 28 mm body size) was molded under the following conditions. Molding temperature: 175 ° C, injection time: 15 seconds, curing time: 1
20 seconds (including injection time), preheating time: 80 ° C. The number of internal voids in the molded product was confirmed by an ultrasonic flaw detector. The number of voids inside and outside the four packages (having a size of 0.5 mmφ or more) was totaled and converted into one package to obtain the number of voids. Evaluation of solder crack resistance: 80 pQFP (thickness 1.5 m
m) was molded, post-cured, and then treated in a thermostatic chamber at 85 ° C./85% for 168 hours. Immediately after the treatment, treatment was carried out at 240 ° C. for 10 seconds using an IR reflow furnace, and external cracks after the reflow treatment were visually observed to evaluate whether or not cracks had occurred in the package among the 8 packages. Examples 2 to 15 According to Table 1 and Table 2, molding materials were obtained in the same manner as in Example 1 and evaluated in the same manner. The evaluation results are shown in Tables 1 and 2. Comparative Examples 1 to 8 According to Table 3, a molding material was obtained and evaluated in the same manner as in Example 1. Table 3 shows the evaluation results. (E-1), (E-2), (H-1) to (H-) used in Examples and Comparative Examples.
3) and (S-11) are shown below. Furthermore (S-
Table 4 shows the structures of 1) to (S-10) and (S-12) to (S-16).

[0015]

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[0016]

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[0017]

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[0018]

[Table 1]

[0019]

[Table 2]

[0020]

[Table 3]

[0021]

[Table 4]

[0022]

By encapsulating a semiconductor element using the resin composition of the present invention, a highly reliable semiconductor device having few voids and excellent solder crack resistance can be obtained. Therefore, a dry pack is not required and the number of steps is reduced.
It has a great effect on cost reduction.

Claims (2)

[Claims] An epoxy resin, a phenol resin curing agent,
An epoxy resin composition comprising a curing accelerator, an inorganic filler, and a silicone oil represented by the formula (1). Embedded image 2. The epoxy resin composition according to claim 1, wherein the amount of the silicone oil represented by the formula (1) is 0.02 to 3.0% by weight based on the total resin composition.