JPH07188515A - Resin composition for semiconductor sealing - Google Patents

Abstract

PURPOSE:To obtain a resin composition for semiconductor sealing, having excellent storage stability at normal temperature and excellent flame-retardancy in spite of the absence of flame-retardant and exhibiting excellent moldability, soldering heat-resistance and reliability in humid atmosphere by compounding a specific resol resin and a phenolic novolak resin at a specific total amount. CONSTITUTION:This resin composition contains (A) a resol resin of formula (l is 0 or 2; m and p each is 0 or <=10; n is 0 or <=4; m+p is <=15), (B) a phenolic novolak resin, (C) a cure accelerator (e.g. 1,8-diazabicycloundecene) and (D) an inorganic filler (e.g. spherical fused silica) as essential components. The sum of the components A and B in the total resin composition is 15-35wt.% and the weight ratio of A/(A+B) is preferably 0.5-0.9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for semiconductor encapsulation which is excellent in room temperature storage property, moldability, solder heat resistance, moisture resistance reliability and flame retardancy.

[0002]

2. Description of the Related Art As a resin component of a resin composition for encapsulating semiconductors such as transistors, capacitors, diodes, ICs, LSIs, a combination of an epoxy resin and a phenol resin curing agent is moldable, reliable, low cost and mass producible. Adopted as a resin suitable for. However, in the recent market trend of miniaturization, weight reduction, and high performance of electronic devices, there are many applications for which the price is low, especially for consumer products, and the demand for semiconductor encapsulation materials is increasing. Is becoming more and more severe. Therefore, there are problems that cannot be solved by the conventional sealing material.

The first problem is that the surface mounting of a semiconductor package causes the package to be rapidly exposed to a high temperature of 200 ° C. or higher during solder dipping or a reflow process, which may cause the package to crack or seal the chip and the chip. There is a problem of solder heat resistance that interface separation from the resin occurs and moisture resistance decreases. Regarding the improvement of solder heat resistance, use of heat-resistant epoxy resin, use of flexible resin for stress reduction during solder immersion and improvement of adhesion to lead frames and chips, addition of adhesion-imparting components, thermal expansion Many proposals have been made such as increasing the amount of the inorganic filler compounded to reduce the coefficient or improving the treatment conditions of the silane coupling agent on the silica surface. However, the fundamental drawback is that epoxy resin has low heat resistance,
In the above environment, the physical durability suddenly decreases,
It is impossible to maintain the strength that can withstand thermal stress. The effects of the above proposals cannot be sufficiently obtained unless the reduction in heat resistance is improved. Although the use of an epoxy resin having a special skeleton structure has achieved a considerable improvement in characteristics, the price is high and the application is naturally limited to high value-added products. The second problem is the increase in total production cost. The use of special raw materials inevitably raises the price of raw materials, and storage conditions often require very strict conditions such as cryogenic storage. The third problem is the presence of brominated epoxies, antimony, etc. from the viewpoint of environmental hygiene. Epoxy resins cannot inherently have flame retardancy that can be used without blending these flame retardants.

[0004]

As a result of various studies on the heat resistance, room temperature storability, and flame retardancy of the resin composition for semiconductor encapsulation, the above characteristics show that the resin component in the encapsulating resin composition has It was clarified that the contribution was very large, and it was found that the characteristics were dramatically improved by using this resin component as a resole resin. That is, the present invention adds a room temperature storability of a resin composition for semiconductor encapsulation, heat resistance for maintaining reliability after a soldering process in surface mounting of a semiconductor package, and a flame retardant such as brominated epoxy or antimony. It is intended to provide a resin composition for semiconductor encapsulation, which can achieve both of excellent flame retardancy without any of the above.

[0005]

The present invention provides a resole resin of the formula (1), a phenol novolac resin, a curing accelerator,
In a resole resin composition containing an inorganic filler as an essential component, the total amount of resole resin and phenol novolac resin in the total resin composition is 15 to 35% by weight, and particularly the weight ratio is resole resin / (resole resin + It is a resin composition for semiconductor encapsulation in which (phenol novolac resin) = 0.5 to 0.9.

[0006]

[Chemical 1] (However, l is a positive number of 0 or 2 or less, m or p is a positive number of 0 or 10 or less, n is a positive number of 0 or 4 and m
+ P represents a positive number of 15 or less. )

The present invention will be described in detail below. The resol resin represented by the formula (1) used in the present invention refers to a monomer, an oligomer, a polymer having a phenolic hydroxyl group and a methylol group, a dimethylene ether group and the like, and mixtures thereof in general. When 1 exceeds 2 as the average structure, the cross-linking density of the cured resin is lowered and the glass transition temperature is lowered,
If m and p exceed 10, or m + p exceeds 15, the resin becomes highly viscous and the flowability and filling property are deteriorated, making low-pressure molding difficult. The phenol novolac resin used in the present invention is a monomer having a phenolic hydroxyl group, an oligomer,
Polymers and mixtures thereof in general, specifically, phenol novolac resin, paraxylylene-modified phenol resin, terpene-modified phenol resin, dicyclopentadiene-modified phenol resin, bisphenol A, or a condensate of triphenolmethane and an aldehyde compound, etc. However, the present invention is not limited thereto. Further, these phenol novolac resins may be used alone or as a mixture.

The most important point of the present invention is that the total amount of the resole resin and the phenol novolac resin contained in the entire resin composition is 15 to 35% by weight. If it is less than 15% by weight, it is difficult to exhibit high fluidity when low-pressure molding is performed using the resin composition as a semiconductor encapsulating material, and defective filling of molded products is likely to occur. Further, if it exceeds 35% by weight, crack resistance and moisture resistance reliability are deteriorated. Further, by changing the compounding ratio of the resole resin and the phenol novolac resin, it is possible to freely adjust the glass transition temperature, the water absorption rate, the bending strength during heating, the bending elastic modulus during heating, and the like. The weight ratio of resole resin / (resole resin + phenol novolac resin) is preferably in the range of 0.5 to 0.9. If it is less than 0.5, the curability during molding deteriorates, the glass transition temperature becomes too low, and the bending strength also decreases.
When it exceeds 0.9, the curing shrinkage ratio becomes large, so that a large package or a package having a complicated structure is apt to warp during molding, and the water absorption rate and bending elastic modulus of the cured product become high, and it is also very brittle. turn into.

The curing accelerator used in the present invention serves as a catalyst for the cross-linking reaction of the resole resin, and specifically includes amine compounds such as hexamine, aniline, ammonia, and 1,8-diazabicycloundecene. Examples thereof include imidazole compounds such as 2-methylimidazole, acids such as p-toluenesulfonic acid, alkali compounds such as calcium hydroxide and magnesium hydroxide, and the present invention is not limited thereto, but preferably 1 An imidazole compound such as, 8-diazabicycloundecene or 2-methylimidazole is used. Further, these curing accelerators may be used alone or as a mixture. The inorganic filler used in the present invention is the same as that used in the epoxy resin composition for semiconductor encapsulation and has an average particle size of 10 to 20.
Examples include fused silica powder having a particle size of 70 μm and a maximum particle size of 70 to 150 μm, crystalline silica powder, alumina, silicon nitride and the like. The blending amount of these inorganic fillers is preferably 65 to 85% by weight in the entire resin composition from the viewpoint of balance between moldability and reliability. Particularly in the case of a compound having a large amount of filler, spherical fused silica is generally used.

The resin composition of the present invention contains the resol resin of the formula (1), a curing accelerator, and an inorganic filler as essential components, but in addition to this, if necessary, a silane coupling agent is representative. Various coupling agents such as carbon black, colorants typified by carbon black, release agents such as natural wax and synthetic wax, and low stress additives such as silicone oil, silicone rubber, and synthetic rubber may be appropriately mixed. When forming a molding material, the desired composition for epoxy resin for semiconductor encapsulation is obtained by heating and kneading the entire composition with a heating kneader or a heating roll, followed by cooling and pulverizing.

The present invention will be specifically described below with reference to examples. Example 1 Resol resin represented by the formula (1) (provided that the average structure is l = 1.1, m = 3.2, n = 1.5, p = 2.2, hereinafter referred to as resole resin 1) 11. 00 parts by weight Phenol novolac resin (softening point 85 ° C., hydroxyl equivalent 104) 5.10 parts by weight 1,8-diazabicycloundecene 0.15 parts by weight fused silica powder 81.55 parts by weight γ-aminopropyltriethoxysilane 0.50 parts by weight Carnauba wax 0.50 parts by weight Carbon black 0.30 parts by weight In producing the resol resin composition with the above-mentioned composition,
After mixing all blended ingredients with a mixer, barrel temperature 1
The mixture was heated and kneaded with a kneader or a roll at 00 ° C., further cooled and pulverized to obtain a sealing material.

Using this material, each item of spiral flow, gelation time, Shore hardness D, cure shrinkage, glass transition temperature, water absorption, bending strength, bending elastic modulus, flame retardancy was measured. Further, the number of cracks and the moisture resistance reliability were evaluated. All samples were molded by transfer molding at a mold temperature of 175 ° C. and curing for 120 seconds. Post cure is 1
It was carried out at 75 ° C for 8 hours. Spiral flow: Using a mold with a spiral inside, transfer molding 175 ° C, effective pressure 70 kgf
The length that the resin has flowed in the mold when cured for about 120 seconds at / cm ² . Gelation time: 2 g of molding material on a hot plate at 175 ° C
Time to put on, spread with a spatula to a size of about 25 mm square and rub on the hot plate, then the resin cures and peels off from the hot plate. Shore D hardness: Measured value of hardness measured by a Shore D hardness meter after transfer molding at 175 ° C., curing for 120 seconds, and mold opening for 10 seconds. Curing shrinkage ratio: According to JIS K 6911. Glass transition temperature: Measured by TMA method. Water absorption rate: According to JIS K 6911. Bending strength: According to JIS K 6911. Flexural modulus: According to JIS K 6911. Flame retardance: UL94 vertical method. Uses a 1.0 mm thick test piece. Number of solder cracks: 80 pQFP package (package size 14 × 20 mm, thickness 1.5 mm, chip size 9 × 9 mm) is molded and post-cured, 85 ° C./85%
It was left for 168 hours in the environment of RH and then immersed in a solder bath at 260 ° C. for 10 seconds. The packages were observed with a microscope, and the number of external cracks (the number of cracked packages / the total number of packages) was expressed as the number of cracks. Moisture resistance reliability: 80 pQFP package was molded, post-cured, left for 24 hours in an environment of 85 ° C. and 85% RH, and then immersed in a solder bath at 260 ° C. for 10 seconds. Next, this package was subjected to PCT treatment at 125 ° C. and 2.3 atm, and the PCT treatment time until the defect rate became 50% was expressed as moisture resistance reliability. The evaluation results are shown in Table 1.

Examples 2 to 6 According to the formulations shown in Table 1, sealing materials were obtained in the same manner as in Example 1. The resole resin of Example 6 is the resole resin represented by the formula (1), provided that the average structure is l = 0.8, m = 4.
5, n = 2.1 and p = 1.8. Hereinafter, this is referred to as resole resin 2. The evaluation results are shown in Table 1. Comparative Examples 1 to 5 According to the formulations in Table 2, the encapsulating material was obtained in the same manner as in Example 1. The resole resin of Comparative Example 5 is the resole resin represented by the formula (1), provided that the average structure is l = 1.2 and m = 1.
3.1, n = 2.2 and p = 12.8. Hereinafter, this is referred to as a resol resin 3. The evaluation results are shown in Table 2.

Comparative Example 6 O-Orthocresol novolac type epoxy resin (softening point 65 ° C., epoxy equivalent 195) 17.50 parts by weight Phenol novolac resin curing agent (softening point 85 ° C., hydroxyl equivalent 104) 7.50 parts by weight 1,8-diazabicycloundecene 0.20 parts by weight fused silica powder 73.50 parts by weight γ-aminopropyltriethoxysilane 0.50 parts by weight Carnaubawak 0.50 parts by weight Carbon black 0.30 parts by weight Examples A sealing material was obtained in the same manner as in 1. The evaluation results are shown in Table 2.

[0015]

[Table 1]

[0016]

[Table 2]

[0017]

EFFECTS OF THE INVENTION According to the present invention, it has excellent room temperature storage properties and is excellent in flame retardance despite not containing a flame retardant such as brominated epoxy or antimony, good moldability, solder heat resistance, A resin composition for semiconductor encapsulation having moisture resistance reliability can be obtained.

[Procedure amendment]

[Submission date] May 12, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

Comparative Example 6 O-Orthocresol novolac type epoxy resin (softening point 65 ° C., epoxy equivalent 195) 17.50 parts by weight Phenol novolac resin curing agent (softening point 85 ° C., hydroxyl equivalent 104) 7.50 parts by weight 1,8-diazabicycloundecene 0.20 parts by weight fused silica powder 73.50 parts by weight γ-aminopropyltriethoxysilane 0.50 parts by weight carnauba wax 0.50 parts by weight carbon black 0.30 parts by weight Examples A sealing material was obtained in the same manner as in 1. The evaluation results are shown in Table 2.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

[0016]

[Table 2]

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Claims (2)

[Claims] 1. A resole resin composition comprising a resole resin of the formula (1), a phenol novolac resin, a curing accelerator, and an inorganic filler as essential components, wherein the total amount of the resole resin and the phenol novolac resin in all resin compositions. Is 15
A resin composition for semiconductor encapsulation, characterized in that [Chemical 1] (However, l is a positive number of 0 or 2 or less, m or p is a positive number of 0 or 10 or less, n is a positive number of 0 or 4 and m
+ P represents a positive number of 15 or less. ) 2. The resin composition for semiconductor encapsulation according to claim 1, wherein a weight ratio of resol resin / (resole resin + phenol novolac resin) = 0.5 to 0.9.