JP3018585B2 - Epoxy resin composition - Google Patents

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 solves the problem of package cracks generated in the soldering step, that is, has excellent solder heat resistance.

[0002]

2. Description of the Related Art Epoxy resins are excellent in heat resistance, moisture resistance, electrical properties, adhesiveness, etc., and can be imparted with various properties by blending and prescription, so that they are used as industrial materials such as paints, adhesives, and electrical insulating materials. Have been. For example, as a method of sealing electronic circuit components such as semiconductor devices, a hermetic seal made of metal or ceramic and a resin seal made of phenol resin, silicone resin, epoxy resin, and the like have been used. In view of the balance of physical properties, resin sealing with epoxy resin is mainly used.

In recent years, in particular, the density of components has been increased in mounting on a printed circuit board. Instead of the conventional "insertion mounting method" in which lead pins are inserted into holes in the board, "surface mounting" in which components are soldered to the board surface is performed. The “mounting method” has become popular. Along with this, the package is also shifting from the conventional DIP (dual inline package) to a thin TSOP (thin small outline package) or QFP (quad flat package) suitable for high-density mounting and surface mounting. .

[0004] With the shift to the surface mounting method, the soldering process, which has not been a problem so far, has become a major problem. In the conventional pin insertion mounting method, the lead portion is only partially heated in the soldering process, but in the surface mounting method, the entire package is immersed in a heating medium and heated. As a soldering method in the surface mounting method, a solder bath immersion, a solder reflow method of heating with a saturated vapor of an inert liquid or infrared rays is used. In any case, the entire package is heated to a high temperature of 210 to 270 ° C. Will be. Therefore, the package sealed with the conventional sealing resin,
There has been a problem that cracks occur in the resin portion at the time of soldering, so that the reliability is reduced and the product cannot be used as a product.

[0005] The occurrence of cracks in the soldering process
It is said that the moisture absorbed between the post-curing and the mounting process explosively evaporates and expands during soldering and heating, and as a countermeasure, various improvements in sealing resins have been studied. .

Conventionally, an orthocresol novolak type epoxy resin is used as an epoxy resin, a phenol novolak resin is used as a curing agent, and an average particle size of 10 to 20 μm is used as an inorganic filler.
Although m-crushed amorphous silica was generally used, the problem of cracking due to heating during surface mounting could not be avoided. Therefore, in order to suppress the occurrence of cracks in the soldering step, an epoxy resin having a biphenyl skeleton is used as the epoxy resin, and crushed amorphous silica having an average particle size of 12 μm or less and an average particle size of 4 μm are used as the inorganic filler.
A method using a combination of spherical amorphous silica having a particle diameter of 0 μm or less (Japanese Patent Laid-Open No. 2-99514) and the like have been proposed.

However, the resins improved by these various methods seem to be effective to some extent at the time of cracking at the time of soldering, however, they are still insufficient.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to solve the problem of package cracks generated in the soldering step, that is, to provide an epoxy resin composition for semiconductor encapsulation having excellent solder heat resistance.

[0009]

The present inventors have solved the above-mentioned problems by blending a specific epoxy resin, an inorganic filler having a specific shape and particle size, and a specific thermoplastic resin. It was found that an epoxy resin composition conforming to the formula (1) was obtained, and the present invention was reached.

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

[0011]

Embedded image

(However, two of R ^{1 to} R ⁸ are 2, 3
An epoxypropoxy group, the rest being hydrogen atoms, C ₁
Selected from lower alkyl group or a halogen atom -C _4, need not all be identical. )) As an essential component, and the amorphous silica (C) is 97 to 60% by weight of crushed amorphous silica having an average particle size of 10 μm or less, and the average particle size is 4 μm or less. Inorganic amorphous silica (C) comprising 3 to 40% by weight of the spherical amorphous silica, wherein the average particle diameter of the spherical amorphous silica is smaller than the average particle diameter of the crushed amorphous silica. It is an epoxy resin composition in which the proportion of the material is 73 to 88% by weight of the whole.

The reasons why the epoxy resin composition of the present invention is excellent in solder heat resistance are not yet clear, but (1) the epoxy resin (a) has only two epoxy groups in one molecule, so that the cured product has (2) epoxy resin having a low cross-linking density, a copolymer (D) of ethylene or an α-olefin and an unsaturated carboxylic acid or a derivative thereof exhibiting low water absorption by making the resin hydrophobic; (A) has toughness (high strength, high elongation) at high temperature due to having a rigid naphthalene skeleton and moderately low crosslink density of the cured product; (3) amorphous silica (C) shape,
It shows high strength at high temperature by a special combination of particle size and reduces local stress to suppress crack propagation. (4) Co-polymerization of ethylene or α-olefin with unsaturated carboxylic acid or its derivative The effect that the coalescing (D) partially reacts with the epoxy resin or hardener to make the resin tougher works synergistically, and has excellent solder heat resistance that cannot be expected from the contribution of each alone. It seems to indicate.

Hereinafter, the configuration of the present invention will be described in detail.

The epoxy resin (A) of 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 and 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-1, Examples thereof include 6-di (2,3-epoxypropoxy) naphthalene and 2,7-di (2,3-epoxypropoxy) naphthalene, and particularly 1,5-di (2,3-epoxypropoxy) naphthalene, 6-
Di (2,3-epoxypropoxy) naphthalene, 2,
7-Di (2,3-epoxypropoxy) naphthalene is preferred.

The proportion of the epoxy resin (a) contained in the epoxy resin (A) is not particularly limited, but in order to achieve a more satisfactory effect, the epoxy resin (a)
Is preferably contained in the epoxy resin (A) in an amount of 50% by weight or more.

The epoxy resin (A) of the present invention
The residue 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. Preferred specific examples are ortho-cresol novolak epoxy resin, phenol novolak epoxy resin, and bisphenol A Type epoxy resin, bisphenol F type epoxy resin, biphenol type epoxy resin and the like.

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

The phenolic curing agent (B) in the present invention
Is not particularly limited as long as it is cured by reacting with the epoxy resin (A). Preferred specific examples include phenol novolak resin, cresol novolak resin, phenol aralkyl resin, bisphenol A, bisphenol F and the like. .

In the present invention, the amount of the phenolic curing agent (B) is usually 3 to 15% by weight, preferably 4 to 15% by weight.
It is 12% by weight. Furthermore, the mixing 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 0. 0 from the viewpoint of mechanical properties and moisture resistance.
It is preferably in the range of 7 to 1.3, particularly 0.8 to 1.2.

In the present invention, the epoxy resin (A)
A curing catalyst may be used to accelerate the curing reaction between 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. For example, 2-methylimidazole, 2-phenylimidazole, 2-phenyl-
Imidazole compounds such as 4-methylimidazole and 2-heptadecylimidazole, tertiary amine compounds such as triethylamine, benzyldimethylamine, α-methylbenzyldimethylamine, and 1,8-diazabicyclo (5,4,0) undecene-7; Triphenylphosphine, tributylphosphine, tri (p-methylphenyl) phosphine, tri (nonylphenyl) phosphine,
Organic phosphine compounds such as triphenylphosphine / triphenylborate and tetraphenylphosphine / tetraphenylborate are exemplified. Of these, organic phosphine compounds are preferred from the viewpoint of moisture resistance, and triphenylphosphine is particularly preferably used.

Depending on the application, two or more of these curing catalysts may be used in combination.
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 having an average particle size of 10 μm or less and 3 to 40% by weight of spherical amorphous silica having an average particle size of 4 μm or less. And the average particle size of the spherical amorphous silica is smaller than the average particle size of the crushed amorphous silica. Here, the average particle diameter means a particle diameter (median diameter) at which the cumulative weight becomes 50%, and is a value measured using, for example, a laser diffraction type particle size distribution analyzer.

The average particle size of the crushed amorphous silica is 10 μm.
If the heat resistance exceeds 10 mm, the solder heat resistance becomes insufficient, and if it is 10 μm or less, there is no particular limitation. However, those having a solder heat resistance of 3 μm or more and 10 μm or less are preferably used, and particularly 3 μm or more and less than 7 μm. Is preferably used.

The average particle size of the spherical amorphous silica is 4 μm.
If it exceeds m, the solder heat resistance becomes insufficient. If it is 4 μm or less, there is no particular limitation, but from 0.01 μm to 4 μm is preferably used from the viewpoint of solder heat resistance.

In the amorphous silica (C) of 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 solder heat resistance is 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.

Further, in the present invention, when the weight ratio of the crushed amorphous silica to the spherical amorphous silica is not in the above range, a cured product having excellent solder 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 in the whole composition.
And more preferably 75 to 85 in the whole composition.
% By weight. If the ratio of the inorganic filler to the entire composition is not in the above range, a cured product having excellent solder heat resistance cannot be obtained.

The ratio of the amorphous silica (C) contained in the inorganic filler is not particularly limited, but the amorphous silica (C) must be mixed with the inorganic filler in order to exhibit a more satisfactory effect. 80% by weight or more, preferably 90% by weight
It is preferable to include the above.

The inorganic filler in the present invention is not particularly limited as long as the amorphous silica (C) is contained in an amount of 80% by weight or more in the inorganic filler. Examples include silica, alumina, magnesia, clay, talc, calcium silicate, titanium oxide, antimony oxide, and various ceramics.

In the present invention, the inorganic filler containing amorphous silica (C) is preferably surface-treated beforehand 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, a silane coupling agent such as epoxy silane, amino silane, and mercapto silane is preferably used.

In the present invention, the ethylene or α-olefin of the copolymer (D) of ethylene or α-olefin with an unsaturated carboxylic acid or a derivative thereof includes ethylene, propylene, butene-1, pentene-1,4- Methylpentene-1, octene-1 and the like,
Among them, ethylene is preferably used. Further, depending on the use, two or more kinds of ethylene or α-olefins 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. Examples of the unsaturated carboxylic acid derivative include an alkyl ester, a glycidyl ester, an acid anhydride and an imide. Preferred specific examples thereof include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate,
Methyl methacrylate, ethyl methacrylate, glycidyl acrylate, glycidyl methacrylate, glycidyl ethacrylate, diglycidyl itaconate, diglycidyl citraconic acid, diglycidyl butenedicarboxylate,
Butenedicarboxylic acid monoglycidyl ester, maleic anhydride, itaconic anhydride, citraconic anhydride, maleic imide, N-phenylmaleimide, itaconic imide, citraconic imide, and the like, among which acrylic acid, methacrylic acid, Ethyl acrylate, glycidyl acrylate, methyl methacrylate, glycidyl methacrylate, and maleic anhydride are preferably used. These unsaturated carboxylic acids or derivatives thereof may be used in combination of two or more depending on the use.

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

AST of copolymer (D) of ethylene or α-olefin with unsaturated carboxylic acid or its derivative
The melt index measured according to the M-D1238 standard is preferably from 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 a derivative thereof is preferably 0.2 to 10 from the viewpoint of solder heat resistance and moldability.
%, Preferably 0.5 to 5% by weight.

In the present invention, the copolymer (D) of ethylene or α-olefin and an unsaturated carboxylic acid or a derivative thereof may be used after being pulverized, cross-linked or otherwise pulverized.

The copolymer (D) of ethylene or α-olefin and an unsaturated carboxylic acid or a derivative thereof may be blended by any procedure. For example, a method in which other components are blended after being melt-mixed with the epoxy resin (A) or the curing agent (B) in advance, and a method in which the epoxy resin (A), the curing agent (B) and other components are blended simultaneously. Can be

The epoxy resin composition of the present invention contains a halogen compound such as a halogenated epoxy resin, a flame retardant such as a phosphorus compound, a flame retardant auxiliary such as antimony trioxide, a coloring agent such as carbon black, a silicone rubber, a modified nitrile. Rubber, elastomer such as modified polybutadiene rubber, thermoplastic resin such as polyethylene, long-chain fatty acid, metal salt of long-chain fatty acid, ester of long-chain fatty acid, amide of long-chain fatty acid, release agent such as paraffin wax optionally added can do.

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

[0041]

The present invention will be described below in detail with reference to examples.

Examples 1 to 9, Comparative Examples 1 to 7 The blends shown in Table 1 and the ethylene or α-
An olefin and a copolymer of an unsaturated carboxylic acid or a derivative thereof were dry-blended by a mixer at the composition ratios shown in Tables 3 and 4 (Examples) and Tables 5 and 6 (Comparative Examples). This was melt-kneaded using a twin-screw extruder having a barrel setting 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 solder heat resistance test, bending test, and water absorption measurement were performed, and the results are shown in Tables 7 and 8.

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

Bending test: ASTM (D790-58T)
Specimens conforming to JIS were molded using a low-pressure transfer molding machine under the conditions of 175 ° C. × 120 seconds, and cured at 175 ° C. for 12 hours. Atmospheric temperature 215 using this test piece
A bending test was performed at a temperature of 100 ° C. by a method based on ASTM (D790-58T), and the bending strength was calculated.

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

[0053]

[Table 7]

[0054]

[Table 8]

As shown in Table 7, the epoxy resin compositions of the present invention (Examples 1 to 9) have excellent solder heat resistance. On the other hand, as shown in Table 8, Comparative Example 1 containing no epoxy resin (a) and Comparative Example 3 not containing a copolymer (D) of ethylene or α-olefin and an unsaturated carboxylic acid or a derivative thereof. And Comparative Example 4, Comparative Example 2 containing no spherical amorphous silica, Comparative Examples 6 and 7, in which the average particle diameters of the crushed amorphous silica and the spherical amorphous silica were respectively larger than the range of the present invention, In Comparative Example 5 where the average particle size of the amorphous silica is larger than the average particle size of the crushed amorphous silica, the solder heat resistance is poor.

[0056]

The epoxy resin composition of the present invention has excellent solder heat resistance and is useful as an epoxy resin composition for semiconductor encapsulation.

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI // H01L 23/29 H01L 23/30 R 23/31 (56) References JP-A-4-50255 (JP, A) JP-A-2- 173153 (JP, A) JP-A-4-50222 (JP, A) JP-A-2-99552 (JP, A) JP-A-2-189326 (JP, A) JP-A-4-306223 (JP, A) JP-A-63-196620 (JP, A) JP-A-63-90530 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 63/00-63/10 C08L 23/08 C08K 3/36 C08G 59/24 C08G 59/62 H01L 23/29

Claims (1)

(57) [Claims] 1. An epoxy resin (A), a phenolic curing agent (B), an amorphous silica (C) and ethylene or α
-A resin composition comprising, as an essential component, a copolymer (D) of an olefin and an unsaturated carboxylic acid or a derivative thereof, wherein the epoxy resin (A) has the formula (I) (However, two of R ^{1 to} R ⁸ are 2,3-epoxypropoxy groups and the rest are selected from a hydrogen atom, a C ₁ -C ₄ lower alkyl group or a halogen atom, and all must be the same.) Epoxy resin (a) represented by
As an essential component, and the amorphous silica (C) is a crushed amorphous silica 9 having an average particle size of 10 μm or less.
7 to 60% by weight and 3 to 40% by weight of spherical amorphous silica having an average particle diameter of 4 μm or less, wherein the average particle diameter of the spherical amorphous silica is smaller than the average particle diameter of the crushed amorphous silica, and The ratio of the inorganic filler containing the crystalline silica (C) is 73
An epoxy resin composition of about 88% by weight.