JPH04370138A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To provide an epoxy resin composition containing a specific epoxy resin, an amorphous silica having specific shape and particle diameter and a specific thermoplastic elastomer, having excellent soldering heat-resistance and suitable for semiconductor sealing. CONSTITUTION:The objective epoxy resin composition for sealing semiconductor is composed of (A) 4-20 wt.% of an epoxy resin containing >=50wt.% of an epoxy compound of formula (two of R<1> to R<8> are 2,3-epoxypropoxy group and the others are H, 1-4C alkyl or halogen), (B) 3-15wt.% of a phenolic hardener (e.g. bisphenol A) and optionally a curing catalyst, (C) 73-88wt.% of an inorganic filler containing preferably >=80wt.% of amorphous silica composed of (C1) 97-60wt.% of crushed amorphous silica having an average particle diameter of <=10mum and (C2) 3-40wt.% of a spherical amorphous silica having an average particle diameter of <=4mum and smaller than that of the component C1 and (D) 0.2-10wt.% of a copolymer of ethylene or an alpha-olefin and an unsaturated carboxylic acid (derivative).

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 that eliminates the problem of package cracks occurring during the soldering process, that is, has excellent solder heat resistance.

0002

[Prior art] Epoxy resins have excellent heat resistance, moisture resistance, electrical properties, adhesive properties, etc., and can be given various properties depending on the formulation, so they are used as industrial materials such as paints, adhesives, and electrical insulation materials. has been done. For example, as methods for encapsulating electronic circuit components such as semiconductor devices, hermetic seals using metals and ceramics, and resin encapsulation using phenolic resins, silicone resins, epoxy resins, etc., have traditionally been used. In view of the balance of physical properties, resin sealing using epoxy resin has become the main method.

Particularly recently, higher density mounting of components on printed circuit boards has been progressing, and instead of the conventional "insertion mounting method" in which lead pins are inserted into holes in the board, a "surface mounting method" in which components are soldered to the surface of the board is being used. ``mounting method'' has become popular. Along with this, packages are also shifting from the conventional DIP (dual inline package) to thin TSOP (thin small outline package) and QFP (quad flat package), which are suitable for high-density mounting and surface mounting. .

[0004] With the shift to the surface mounting method, the soldering process, which did not pose much of a problem in the past, has become a major problem. In the conventional pin insertion mounting method, only the leads are partially heated during the soldering process, but in the surface mounting method, the entire package is immersed in a heating medium and heated. Soldering methods used in the surface mount method include immersion in a solder bath, saturated vapor of an inert liquid, and a solder reflow method in which heating is performed using infrared rays, but in either method, the entire package is heated to a high temperature of 210 to 270 degrees Celsius. It turns out. Therefore, packages sealed with conventional sealing resin,
There was a problem that cracks occurred in the resin part during soldering, reducing reliability and making it unusable as a product.

[0005] The occurrence of cracks in the soldering process is
This is said to be caused by moisture absorbed between post-curing and the mounting process that explosively turns into water vapor and expands during soldering heat, and various improvements to the sealing resin are being considered as countermeasures. .

Conventionally, an orthocresol novolak type epoxy resin was used as the epoxy resin, a phenol novolac resin was used as the curing agent, and an average particle size of 10 to 20 μm was used as the inorganic filler.
Although it has been common to use crushed amorphous silica of 200 m, it has not been possible to avoid the problem of cracks occurring due to heating during surface mounting. Therefore, in order to suppress the occurrence of cracks during the soldering process, an epoxy resin having a biphenyl skeleton was used as the epoxy resin, and crushed amorphous silica with an average particle size of 40 μm or less was used as an inorganic filler.
A method using a combination of spherical amorphous silica with a particle size of μm or less (Japanese Patent Application Laid-open No. 2-99514) has been proposed.

[0007] However, although the resins improved by these various methods seem to have some effect on cracks during soldering, they are still not sufficient.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an epoxy resin composition for semiconductor encapsulation that eliminates the problem of package cracks occurring in the soldering process, that is, has excellent solder heat resistance.

[0009]

[Means for Solving the Problems] The present inventors have solved the above problems by blending a specific epoxy resin, an inorganic filler with a specific shape and particle size, and a specific thermoplastic resin. The present invention was achieved by discovering that an epoxy resin composition meeting the above requirements can be obtained.

[0010] That is, the present invention provides an epoxy resin (A),
A resin composition containing as essential components a phenolic curing agent (B), amorphous silica (C), and a copolymer of ethylene or α-olefin and an unsaturated carboxylic acid or a derivative thereof. The epoxy resin (A)
is the formula (I)

[0011]

[Case 2]

(However, two of R1 to R8 are 2
, 3-epoxypropoxy group, the rest are hydrogen atoms,
They are selected from C1 to C4 lower alkyl groups or halogen atoms, and do not need to be all the same. ) contains the epoxy resin (a) represented by (a) as an essential component, and the amorphous silica (C) is 97 to 60% by weight of crushed amorphous silica with an average particle size of 10 μm or less and an average particle size of 4 μm or less 3 to 40% by weight of spherical amorphous silica, the average particle size of the spherical amorphous silica is smaller than the average particle size of crushed amorphous silica, and an inorganic filler containing amorphous silica (C). This is an epoxy resin composition in which the proportion of the material is 73 to 88% by weight of the whole.

The reason why the epoxy resin composition of the present invention has excellent soldering heat resistance is not yet clear, but (1) the epoxy resin (a) has only two epoxy groups in one molecule; (2) The epoxy resin exhibits low water absorption due to a moderate decrease in crosslink density and the copolymer (D) of ethylene or α-olefin and unsaturated carboxylic acid or its derivative by making the resin hydrophobic. (a) exhibits toughness (high strength, high elongation) at high temperatures due to having a rigid naphthalene skeleton and moderately low crosslinking density of the cured product; (3) amorphous silica (C); shape,
It exhibits high strength at high temperatures due to a special combination of particle sizes, reduces local stress and inhibits crack propagation, and (4) copolymerization of ethylene or α-olefin with unsaturated carboxylic acid or its derivatives. Combine (D
) partially reacts with the epoxy resin or curing agent to strengthen the resin, and the effects work synergistically to provide excellent soldering heat resistance that cannot be expected from the individual contributions of each component. I think that the.

The configuration of the present invention will be explained in detail below.

The epoxy resin (A) in the present invention contains the epoxy resin (a) represented by the above formula (I) as an essential component.

Preferred specific examples of the epoxy resin (a) in the present invention include 1,5-di(2,3-epoxypropoxy)naphthalene, 1,5-di(2,3-epoxypropoxy)-7-methyl naphthalene, 1,6
-di(2,3-epoxypropoxy)naphthalene, 1,
6-di(2,3-epoxypropoxy)-2-methylnaphthalene, 1,6-di(2,3-epoxypropoxy)
-8-Methylnaphthalene, 1,6-di(2,3-epoxypropoxy)-4,8-dimethylnaphthalene, 2-bromo-1,6-di(2,3-epoxypropoxy)naphthalene, 8-bromo- Examples include 1,6-di(2,3-epoxypropoxy)naphthalene, 2,7-di(2,3-epoxypropoxy)naphthalene, and especially 1,5-di(2,3-epoxypropoxy)naphthalene.
Di(2,3-epoxypropoxy)naphthalene, 1,6
-di(2,3-epoxypropoxy)naphthalene,
2,7-di(2,3-epoxypropoxy)naphthalene is preferred.

[0017] There is no particular restriction on the proportion of epoxy resin (a) contained in epoxy resin (A), but in order to exhibit a more sufficient effect, it is necessary to
It is preferable that the epoxy resin (A) contains 50% by weight or more of the following.

[0018] Furthermore, the epoxy resin (A) in the present invention
The rest is not particularly limited as long as the epoxy resin (a) is contained in the epoxy resin (A) in an amount of 50% by weight or more, but preferred specific examples include orthocresol novolac type epoxy resin, phenol novolac type epoxy resin, and bisphenol A. Examples include biphenol type epoxy resin, bisphenol F type epoxy resin, and biphenol type epoxy resin.

In the present invention, the blending amount of the epoxy resin (A) is usually 4 to 20% by weight, preferably 5 to 15% by weight.
It is.

[0020] Phenolic curing agent (B) in the present invention
is not particularly limited as long as it reacts with the epoxy resin (A) to cure it, but preferred specific examples include phenol novolak resin, cresol novolac resin, phenol aralkyl resin, bisphenol A, bisphenol F, etc. .

In the present invention, a phenolic curing agent (B
) is usually 3 to 15% by weight, preferably 4 to 12% by weight.
Weight%. Furthermore, the compounding ratio of the epoxy resin (A) and the phenolic curing agent (B) is such that the chemical equivalent ratio of hydroxyl group/epoxy group is from 0.7 to 0.7 from the viewpoint of mechanical properties and moisture resistance.
It is preferably in the range of 1.3, particularly 0.8 to 1.2.

[0022] Furthermore, in the present invention, epoxy resin (A)
A curing catalyst may be used to promote the curing reaction of the phenolic curing agent (B) and the phenolic curing agent (B). The curing catalyst is not particularly limited as long as it promotes the curing reaction, and examples thereof include 2-methylimidazole, 2-phenylimidazole, and 2-phenyl-
Imidazole compounds such as 4-methylimidazole and 2-heptadecylimidazole, tertiary amine compounds such as triethylamine, benzyldimethylamine, α-methylbenzyldimethylamine, 1,8-diazabicyclo(5,4,0)undecene-7, Triphenylphosphine, tributylphosphine, tri(p-methylphenyl)
Examples include organic phosphine compounds such as phosphine, tri(nonylphenyl)phosphine, triphenylphosphine/triphenylborate, and tetraphenylphosphine/tetraphenylborate. Among them, from the viewpoint of moisture resistance, organic phosphine compounds are preferred, and triphenylphosphine is particularly preferably used.

[0023] These curing catalysts may be used in combination of two or more depending on the application, and the amount added is determined by the amount of the epoxy resin (A).
The range of 0.5 to 5 parts by weight per 100 parts by weight is preferred.

The amorphous silica (C) in the present invention is composed of 97 to 60% by weight of crushed amorphous silica with an average particle size of 10 μm or less and 3 to 40% by weight of spherical amorphous silica with an average particle size of 4 μm or less. The average particle size of the spherical amorphous silica is smaller than the average particle size of the crushed amorphous silica. The average particle size herein means the particle size (median diameter) that accounts for 50% of the cumulative weight, and is a value measured using, for example, a laser diffraction particle size distribution analyzer.

[0025] The average particle size of crushed amorphous silica is 10 μm.
If it exceeds 10 μm, the soldering heat resistance becomes insufficient, and if it is 10 μm or less, there is no particular restriction, but from the viewpoint of soldering heat resistance, 3 μm or more and 10 μm or less are preferably used, especially 3 μm or more and less than 7 μm. Those are preferably used.

[0026] Furthermore, the average particle size of the spherical amorphous silica is 4μ.
If it exceeds m, the soldering heat resistance becomes insufficient, and if it is 4 μm or less, there is no particular restriction, but from the viewpoint of soldering heat resistance, 0.01 μm or more and 4 μm or less are preferably used.

In the amorphous silica (C) used in the present invention, it is important that the average particle size of the spherical amorphous silica is smaller than the average particle size of the crushed amorphous silica. If the average particle size of the spherical amorphous silica is larger than the average particle size of the crushed amorphous silica, the soldering heat resistance will be greatly reduced. The average particle size of the spherical amorphous silica may be smaller than the average particle size of the crushed amorphous silica, but preferably the average particle size of the spherical amorphous silica is 2 times the average particle size of the crushed amorphous silica. /3 or less, particularly preferably 1/2 or less.

Furthermore, in the present invention, if the weight ratio of crushed amorphous silica to spherical amorphous silica is not within the above range, a cured product with excellent soldering heat resistance cannot be obtained.

In the present invention, the proportion of the inorganic filler containing amorphous silica (C) is 73 to 88% by weight of the entire composition.
and more preferably 75 to 85 in the entire composition.
Weight%. If the ratio of the inorganic filler to the entire composition is not within the above range, a cured product with excellent soldering heat resistance cannot be obtained.

[0030]Although there is no particular restriction on the proportion of amorphous silica (C) contained in the inorganic filler, in order to exhibit a more sufficient effect, it is necessary to add amorphous silica (C) to the inorganic filler. Usually 80% by weight or more, preferably 90% by weight
It is preferable to contain the above amount.

Further, the inorganic filler in the present invention is not particularly limited as long as it contains the above-mentioned amorphous silica (C) in an amount of 80% by weight or more, but as a preferred specific example, crystalline silica Examples include silica, alumina, magnesia, clay, talc, calcium silicate, titanium oxide, antimony oxide, and various ceramics.

[0032] In the present invention, the inorganic filler containing amorphous silica (C) is preferably used after being surface-treated with a coupling agent such as a silane coupling agent or a titanate coupling agent from the viewpoint of moisture resistance reliability. . As the coupling agent, silane coupling agents such as epoxysilane, aminosilane, and mercaptosilane are preferably used.

In the present invention, the ethylene or α-olefin of the copolymer (D) of ethylene or α-olefin and an unsaturated carboxylic acid or its derivative includes ethylene, propylene, butene-1, pentene-1, 4- Examples include methylpentene-1, octene-1, etc.
Among them, ethylene is preferably used. Moreover, depending on the use, two or more types of ethylene or α-olefin may be used in combination. Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, and butenedicarboxylic acid. Furthermore, examples of derivatives of unsaturated carboxylic acids include alkyl esters, glycidyl esters, acid anhydrides, and imides. Preferred specific examples include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate,
Methyl methacrylate, ethyl methacrylate, glycidyl acrylate, glycidyl methacrylate, glycidyl ethacrylate, diglycidyl itaconate, diglycidyl citraconate, butene dicarboxylic acid diglycidyl ester,
Examples include butene dicarboxylic acid monoglycidyl ester, maleic anhydride, itaconic anhydride, citraconic anhydride, maleic acid imide, N-phenylmaleic acid imide, itaconic acid imide, citraconic acid imide, among others, acrylic acid, methacrylic acid, Ethyl acrylate, glycidyl acrylate, methyl methacrylate, glycidyl methacrylate, and maleic anhydride are preferably used. Two or more of these unsaturated carboxylic acids or derivatives thereof may be used in combination depending on the purpose.

The amount of copolymerization of the unsaturated carboxylic acid or its derivative is preferably 1 to 50% by weight from the viewpoint of improving soldering heat resistance.

AST of copolymer (D) of ethylene or α-olefin and unsaturated carboxylic acid or its derivative
The melt index measured according to M-D1238 standard is preferably 1 to 3000 from the viewpoint of solder heat resistance and moldability.

The amount of the copolymer (D) of ethylene or α-olefin and unsaturated carboxylic acid or its derivatives is 0.2 to 10% of the total from the viewpoint of soldering heat resistance and moldability.
% by weight, preferably 0.5 to 5% by weight.

In the present invention, the copolymer (D) of ethylene or α-olefin and unsaturated carboxylic acid or its derivative may be used after being pulverized in advance by pulverization, crosslinking or other methods.

Further, any procedure can be used for blending the copolymer (D) of ethylene or α-olefin with unsaturated carboxylic acid or its derivative. Examples include a method in which the epoxy resin (A) or curing agent (B) is melt-mixed in advance and then blended with other components, and a method in which the epoxy resin (A), curing agent (B), and other components are blended simultaneously. It will be done.

The epoxy resin composition of the present invention contains halogen compounds such as halogenated epoxy resins, flame retardants such as phosphorus compounds, flame retardant aids such as antimony trioxide, colorants such as carbon black, silicone rubber, and modified nitrile. Optionally add release agents such as rubber, elastomers such as modified polybutadiene rubber, thermoplastic resins such as polyethylene, long chain fatty acids, metal salts of long chain fatty acids, esters of long chain fatty acids, amides of long chain fatty acids, paraffin wax, etc. can do.

The epoxy resin composition of the present invention is preferably melt-kneaded, and can be produced by melt-kneading using a known kneading method such as a kneader, roll, single-screw or twin-screw extruder, or co-kneader. Ru.

[0041]

[Examples] The present invention will be specifically explained below with reference to Examples.

Examples 1 to 9, Comparative Examples 1 to 7 The formulations shown in Table 1 and the copolymers of ethylene or α-olefin and unsaturated carboxylic acids or derivatives thereof shown in Table 2 were
Table 3, Table 4 (Example) and Table 5, Table 6 (Comparative Example) respectively
Dry blending was performed using a mixer at the composition ratio shown in . This was melt-kneaded using a twin-screw extruder with a barrel set temperature of 90°C, and then cooled and pulverized to produce an epoxy resin composition.

[0043]

[Table 1]

[0044]

[Table 2]

[0045]

[Table 3]

[0046]

[Table 4]

[0047]

[Table 5]

[0048]

[Table 6]

Using this composition, the following soldering heat resistance test, bending test, and water absorption measurement were conducted, and the results are shown in Tables 7 and 8.

Solder heat resistance test: 32 80-pin QFP devices (package size: 17 x 17 x 1.7 mm, chip size: 9 x 9 x 0.5 mm) were molded using a low pressure transfer molding machine at 175°C for 120 seconds. It was molded and cured at 175°C for 12 hours. After humidifying this test device at 85°C/85%RH for a predetermined time,
Put 16 pieces into a VPS (vapor phase solder reflow) furnace heated to 215℃ for 90 seconds, and the remaining 16 pieces
The devices were immersed in a solder bath heated to 260° C. for 10 seconds, and devices with cracks were judged as defective.

Bending test: ASTM (D790-58T)
A test piece conforming to the above was molded using a low-pressure transfer molding machine at 175°C for 120 seconds, and cured at 175°C for 12 hours. Using this test piece, the ambient temperature was 215
A bending test was conducted at ℃ in accordance with ASTM (D790-58T), and the bending strength was calculated.

Water absorption measurement: 80 used for soldering heat resistance test
The water absorption rate was measured when the pinQFP test device was humidified at 85° C./85% RH for a predetermined period of time.

[0053]

[Table 7]

[0054]

[Table 8]

As seen in Table 7, the epoxy resin compositions of the present invention (Examples 1 to 9) have excellent soldering heat resistance. On the other hand, as shown in Table 8, epoxy resin (a
) Comparative Example 1, a copolymer of ethylene or α-olefin and an unsaturated carboxylic acid or its derivative (
Comparative Examples 3 and 4 that do not contain D), Comparative Example 2 that does not contain spherical amorphous silica, and comparisons in which the average particle diameters of crushed amorphous silica and spherical amorphous silica are each larger than the range of the present invention. Examples 6, Comparative Example 7, Comparative Example 5 in which the average particle size of the spherical amorphous silica is larger than the average particle size of the crushed amorphous silica, etc., all have poor solder heat resistance.

[0056]

EFFECTS OF THE INVENTION The epoxy resin composition of the present invention has excellent soldering heat resistance and is useful as an epoxy resin composition for semiconductor encapsulation.

Claims (1)

[Claims] Claim 1: Epoxy resin (A), phenolic curing agent (B), amorphous silica (C), and copolymer of ethylene or α-olefin and unsaturated carboxylic acid or its derivative (D) are essential. A resin composition containing as a component, the epoxy resin (A) having the formula (I) [Formula 1] (However, two of R1 to R8 are 2,3-epoxypropoxy groups, and the remaining is a hydrogen atom, C1 to C4
are selected from lower alkyl groups or halogen atoms, and do not need to be all the same. ) contains the epoxy resin (a) represented by (a) as an essential component, and the amorphous silica (C) is 97 to 60% by weight of crushed amorphous silica with an average particle size of 10 μm or less and an average particle size of 4 μm or less An inorganic filler consisting of 3 to 40% by weight of spherical amorphous silica, the average particle size of the spherical amorphous silica being smaller than the average particle size of crushed amorphous silica, and containing amorphous silica (C). An epoxy resin composition in which the proportion of is 73 to 88% by weight of the whole.