JPH0232115A - Epoxy resin composition for sealing semiconductor - Google Patents

Abstract

PURPOSE:To obtain the subject composition having excellent soldering stress resistance by using a specific epoxy resin, a phenolic resin hardener, a specific filler and a cure accelerator as essential components. CONSTITUTION:The objective composition contains, as essential components, (A) an epoxy resin containing 50-100wt.% (based on the whole epoxy resin) of a polyfunctional epoxy resin of formula (n and m are integer of >=0; n+m is 1-10; R1-R3 are H, alkyl or halogen and at least one of R1-R3 is a functional group), (B) a phenolic resin hardener, (C) a filler containing 5-100wt.% (based on the whole filler) of porous silica powder having an average particle diameter of 5-40mum, an apparent density of 0.1-0.6g/cc and a specific surface area of 5-20m<2>/g and (D) a cure accelerator (e.g., diazabicycloundecene).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an epoxy resin composition for semiconductor encapsulation that has excellent solder stress resistance.

[Conventional technology] Semiconductor-related technology has progressed in the direction of improving packaging density due to the recent trend toward lighter, thinner, and smaller devices. To this end, memory density is increasing and the mounting method is shifting from through-hole mounting to surface mounting. Therefore, the package is a traditional DI
SOP is a small and thin flat package for surface mounting from P type.

These are replaced by SOJ and PLCC, and there are problems such as package cracks due to stress and a decrease in moisture resistance due to these cranks.

In particular, when soldering leads in the surface mounting process, the package is sometimes subject to rapid temperature changes, and the problem of cranking of the package due to this is attracting attention.

In order to solve these problems, soldering requires the addition of thermoplastic oligomers (Japanese Patent Laid-Open No. 62/1999) to alleviate the thermal shock caused by soldering.
-115849) and addition of various silicone compounds (JP-A-62-115850, 62-11665)
4, 62-128162) and silicone modification (Japanese Patent Application Laid-Open No. 62-136860), these methods sometimes cause cracks in the package during soldering, resulting in poor reliability. However, it has not been possible to obtain an epoxy resin composition for semiconductors with excellent properties.

-4. In order to obtain a heat-resistant epoxy resin composition with excellent solder stress resistance, the use of a polyfunctional epoxy resin as the resin system (Japanese Patent Application Laid-open No. 168620/1983) has been considered; Although the use of epoxy resin increases the crosslinking density and improves heat resistance, the solder stress resistance is insufficient, especially when exposed to high temperatures such as 200°C to 300°C.

[Problem to be solved by the invention]

In order to solve these problems, the present invention has developed an epoxy resin for semiconductor encapsulation that has extremely excellent solder stress resistance by using a multifunctional epoxy resin represented by formula I as an epoxy resin and porous silica powder as a filler. N@ provides the composition.

[Means to solve the problem]

The epoxy resin composition of the present invention has extremely superior solder stress resistance compared to conventional sealing resin compositions.

(n and m are integers greater than or equal to 0, n+m=1 to 10, R+ Rz R3 in the formula are the same or different, H1
The epoxy resin represented by the above formula I is a polyfunctional resin having three or more epoxy groups in one molecule. This polyfunctional epoxy resin has an average particle size of 5 to 40 μm, an apparent density of 0.1 to 0.6 g/cc, and a specific surface area of 5 to 20 n(/g). By using silica powder in combination, it is possible to obtain an epoxy resin composition with extremely excellent solder stress resistance that could not be obtained by using only a polyfunctional epoxy resin.

By adjusting the amount of such epoxy resin used, the solder stress resistance can be maximized. In order to obtain the effect of solder stress resistance, it is preferable to use the polyfunctional epoxy resin represented by formula (1) in an amount of 50% by weight or more, more preferably 70% by weight or more of the epoxy resin.

If it is less than 50% by weight, the crosslinking density will not increase and the solder stress resistance will be insufficient. Furthermore, R1 in the formula is a methyl group, Rz
is an L-butyl group, and R3 is preferably a methyl group and a hydrogen atom.The ratio of n and m in formula 0 is such that n is 1 and m is 0.
The range is preferably 1 to 0.6, more preferably 0.
A range of 2 to 0.4 is preferable.

In this case, when n is 1, if the ratio of m is smaller than 0.1, the curing properties during molding will not improve and the moldability will tend to deteriorate, and if the ratio of m is larger than 0.6, water absorption will decrease. temperature, thermal shock during solder immersion is large, and solder stress resistance tends to be poor.

Furthermore, when using an epoxy resin with less than two functional groups, the crosslinking density does not increase, the heat resistance becomes poor, and the effect of solder stress resistance cannot be obtained.

The epoxy resin referred to here refers to all those having an epoxy group, such as bisphenol type epoxy resin,
Refers to novolac type epoxy resin, triazine core-containing epoxy resin, etc.

As a filler, a porous silica powder having an average particle size of 20 to 60 μm, an apparent density of 0.1 to 0.6 g/cc, and a specific surface area of 5 to 20 rrr/g is used. It is used in an amount of 5 to 100% by weight.

Porous silica powder has an average particle size of less than 5 μm or 4 μm.
0 (tm), the fluidity decreases, and in any case,
Also, if the apparent density exceeds 0.6 g/cc, cracks are likely to occur due to soldering heat stress, and moisture resistance decreases, which is undesirable.

Furthermore, if the specific surface area is less than 5 m/g, cracks are likely to occur during the soldering process, and moisture resistance will decrease.
If it exceeds 0 m2f/g, the fluidity will drop significantly, which is not preferable.

In addition, porous silica powder is added at 5% of the amount of filler used.
If it is less than that, cracks are likely to occur during the soldering process, moisture resistance is reduced, and the desired characteristics cannot be obtained.

Moreover, if the amount of porous silica powder exceeds 80% of the amount of the filler used, the fluidity will decrease and the moldability will deteriorate, making it unsuitable for practical use.

In addition, examples of fillers other than porous silica powder include ordinary silica powder and alumina, with fused silica powder being particularly preferred.

The curing accelerator used in the present invention may be one that promotes the reaction between the epoxy group and the phenolic hydroxyl group, and a wide variety of those commonly used in sealing materials can be used, such as diaza. Bicycloundesene (DBU),
Triphenylphosphine (TPP), dimethylbenzylamine (BDMA) and 2methylimidazole (2MZ)
etc. may be used alone or in combination of two or more.

The epoxy resin composition for sealing of the present invention contains an epoxy resin, a curing agent, an inorganic filler, and a curing accelerator as essential components,
In addition to this, silane coupling agents, brominated epoxy resins, antimony trioxide, flame retardants such as hexabromobenzene, colorants such as carbon black and red iron, mold release agents such as natural wax and synthetic wax, and silicone There is no problem in appropriately blending various additives such as low stress additives such as oil and rubber.

In addition, in order to produce the epoxy resin composition for sealing of the present invention as a molding material, the epoxy resin, curing agent curing accelerator, filler, and other additives are thoroughly and uniformly mixed using a mixer or the like, and then further A molding material can be obtained by melt-kneading with a hot roll or kneader, cooling, and pulverizing.

These molding materials are used for sealing electronic or electrical parts,
Can be applied to coating, insulation, etc.

〔Example〕

Example 1 15 parts by weight of tosas(hydroxyalkylphenyl)methane triglycidyl ether represented by the following composition formula (n) (n: m-3: 1, n0 m-lN10) 5 parts by weight of ortho-cresol novolak epoxy resin Fer Novolac resin 10 parts by weight Porous silica powder (average particle size 15 μm, apparent density 0.3 g/
cc, specific surface area 7nf/g)
35 parts by weight fused silica powder 3
3.8 parts by weight Triphenylphosphine 0.
2 parts, 1 part, carbon black, 0.5 parts by weight, carnauba wax, 0.5 parts by weight, were mixed at room temperature in a mixer, and the mixture was heated to 70 to 100 ml.
The mixture was kneaded using twin-screw rolls, cooled, and then ground to obtain a molding material.

The obtained molding material was made into tablets, and 6 x 6 m chips were made into 52p chips for solder crack testing using a low-pressure transfer molding machine at 175°C, 70 kg/d, and 120 seconds.
3 x 6 for sealing in a package and for solder moisture resistance test.
The cabinet chip was sealed in a 16PsOP package.

The following solder crack test and solder moisture resistance test were conducted on the sealed test device.

Solder crank test: sealed test element at 85℃, 8
48H and 72Hr treatment in a ring environment of 5% RH,
Thereafter, it was immersed in a solder bath at 250° C. for 10 seconds, and external cracks were observed using a microscope.

Solder moisture resistance test: sealed test element at 85, 85
Under %RH environment? Treated for 2 hours, then heated to 250"C
Pressure tank 7 car test (
(125° C., 100% RH) to measure oven failure of the circuit.

The test results are shown in Table 1.

Examples 2 to 7 Molding materials were obtained in the same manner as in Example (2) by blending according to the formulations in Table 1. A sealed molded product for testing was obtained using this molding material, and a solder crank test and a solder moisture resistance test were conducted in the same manner as in Example 1 using this molded product. Test results first
Shown in the table.

Comparative Examples 1 to 6 Molding materials were obtained in the same manner as in Example 1 by blending according to the formulations in Table 1. A sealed molded article for testing was obtained using this molding material, and a solder crack test and a solder moisture resistance test were conducted in the same manner as in Example 1 using this molded article. Test results first
Shown in the table.

〔Effect of the invention〕

According to the present invention, it is possible to obtain an epoxy resin composition that has heat resistance and flexibility that could not be obtained using conventional techniques. It has excellent crack resistance and good moisture resistance, so it is reliable when used for sealing electronic and electrical components, coating insulation, etc., especially in highly integrated large chip tC mounted on surface mount packages. Suitable for products that require high performance.

Claims (1)

[Claims] (1) (A) Multifunctional epoxy resin (n
and m are integers of 0 or more, n+m = 1 to 10, and R_1R_2R_3 in the formula are each the same or different and are selected from H, an alkyl group, and a halogen such as Cl, Br, and at least one functional group. Epoxy resin (B) phenolic resin curing agent (C) containing 50 to 100% by weight of 50 to 100 wt.
1 to 0.6 g/cc, and a specific surface area of 5 to 20 m
^2f/g porous silica powder to the total amount of filler
Filler containing ~100% by weight. (D) An epoxy resin composition for semiconductor encapsulation, which contains a curing accelerator as an essential component.