JPH0733429B2 - Epoxy resin composition - Google Patents

Description

Detailed Description of the Invention

The present invention relates to an epoxy resin composition for semiconductor encapsulation , which solves the problem of package cracks that occur during the soldering process, that is, has excellent solder heat resistance.

[0002]

2. Description of the Related Art Epoxy resins are excellent in heat resistance, moisture resistance, electrical characteristics, adhesiveness, etc., and can be given various characteristics by blending formulation, so they are used as industrial materials such as paints, adhesives and electrical insulation materials. Has been done. For example, as a method for sealing electronic circuit parts such as semiconductor devices, hermetic sealing using metal or ceramics and resin sealing using phenol resin, silicone resin, epoxy resin, etc. have been proposed. However, resin sealing with an epoxy resin is mainly used from the viewpoint of the balance of economy, productivity and physical properties.

On the other hand, recently, densification and automation have also been promoted in mounting components on a printed circuit board. Instead of the conventional "insertion mounting method" in which lead pins are inserted into holes in the substrate, the components are soldered on the surface of the substrate. "Surface mounting method" to attach is becoming popular. Along with that, the package will also be DI
P (dual in-line package) is shifting to thin TSOP (thin small outline package) and QFP (quad flat package) suitable for high-density mounting and surface mounting.

With the shift to the surface mounting method, the soldering process, which has not been a problem so far, has become a big 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 dipping method, a solder reflow method of heating with saturated vapor of an inert liquid or infrared rays is used, and in any method, the entire package is heated to a high temperature of 210 to 270 ° C. It will be. Therefore, the package sealed with the conventional sealing resin is
There was a problem that a crack was generated in the resin portion during soldering, the reliability was lowered, and the product could not be used as a product.

The occurrence of cracks in the soldering process is
It is said that moisture absorbed between the post-curing and the mounting process explodes into steam and expands during soldering heating, and various measures to improve the encapsulating resin are being investigated as measures against this. .

Conventionally, an ortho-cresol novolac type epoxy resin is used as an epoxy resin, and a phenol novolac resin is used as a curing agent, and an average particle size is 10 to 20 μm as an inorganic filler.
It was common to use crushed fused silica of m.
We were unable to avoid the problem of cracking caused by solder during surface mounting.

Therefore, a method has been proposed in which an epoxy resin having a biphenyl skeleton is used as the epoxy resin, and a powdery filler having an average particle size of 14 μm or less is used in combination as the inorganic filler (JP-A-64-87616). However, it cannot be said that the solder heat resistance is sufficient.

Also, although there is no description about solder heat resistance,
Coarse-grained silica having an average particle size of 7 to 30 μm and an average particle size of 0.1
A method using a combination of 3 μm monodisperse spherical silica (Japanese Patent Laid-Open No. 1-263131) has been proposed.
However, this method only improves the fluidity of the encapsulant and has a low solder heat resistance level.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a semiconductor encapsulating epoxy resin composition that solves the problem of package cracks that occur during the soldering process, that is, has excellent solder heat resistance.

[0010]

The present inventors have solved the above-mentioned problems by using a specific epoxy resin and fused silica composed of a specific combination of particle size and shape, and met the objectives. The present invention has been achieved by finding that an epoxy resin composition can be obtained.

That is, the present invention relates to an epoxy resin (A),
A resin composition comprising a curing agent (B) and fused silica (C) as essential components, wherein the epoxy resin (A) is represented by the following general formula (I):

[0012]

[Chemical 2]

(However, R ^{1 to} R ⁸ are hydrogen atoms, and C ₁ to
Selected from a C ₄ lower alkyl group or a halogen atom,
Not all have to be the same. ) An epoxy resin (a) represented by the formula (1) is contained as an essential component, and the fused silica (C) has a crushed fused silica content of 97 to 60% by weight and an average particle diameter of 4 μm or less. 3 to 40% by weight, the average particle diameter of the spherical fused silica is smaller than the average particle diameter of the crushed fused silica, and the proportion of the inorganic filler containing the fused silica (C) is 75 to 70% by weight.
The epoxy resin composition for semiconductor encapsulation is 90% by weight.

The reason why the epoxy resin composition of the present invention is excellent in solder heat resistance is not yet clear, but (1) the epoxy resin essential to the present invention is a bifunctional one having only two epoxy groups in one molecule. By being an epoxy resin, the cross-linking density of the cured product is appropriately reduced to exhibit low water absorption,
(2) It exhibits toughness (high strength, high elongation) at high temperature because the epoxy resin has a biphenyl skeleton with high heat resistance, although the crosslink density of the cured product is low to some extent.
(3) Reinforcement effect is increased and stress is dispersed by reducing the particle size of fused silica. (4) Local stress is improved by combining crushed fused silica and spherical fused silica having a smaller average particle size. It is thought that the crack resistance may be reduced and crack propagation may be suppressed, and that the effects such as synergistically work together to exhibit excellent solder heat resistance that cannot be predicted from the individual contributions of each. Be done.

The structure of the present invention will be described in detail below.

The epoxy resin (A) in the present invention has the following general formula (I):

[0017]

[Chemical 3]

(Wherein R ^{1 to} R ⁸ are hydrogen atoms, C ₁ to
Selected from a C ₄ lower alkyl group or a halogen atom,
Not all have to be the same. ) It is necessary to contain the epoxy resin (a) represented by this as an essential component. If the epoxy resin (a) is not contained, the effect of preventing crack generation in the soldering process is not exerted.

Preferred specific examples of the epoxy resin (a) in the present invention include 4,4'-bis (2,3-epoxypropoxy) biphenyl and 4,4'-bis (2,3-).
Epoxypropoxy) -3,3 ', 5,5'-tetramethylbiphenyl, 4,4'-bis (2,3-epoxypropoxy) -3,3', 5,5'-tetramethyl-2-
Chlorobiphenyl, 4,4'-bis (2,3-epoxypropoxy) -3,3 ', 5,5'-tetramethyl-2
-Bromobiphenyl, 4,4'-bis (2,3-epoxypropoxy) -3,3 ', 5,5'-tetraethylbiphenyl, 4,4'-bis (2,3-epoxypropoxy) -3,3 Examples include ′, 5,5′-tetrabutylbiphenyl, 4,4′-bis (2,3-epoxypropoxy) biphenyl, 4,4′-bis (2,3-epoxypropoxy) -3,3 ′. , 5,5'-Tetramethylbiphenyl is particularly preferred.

The ratio of the epoxy resin (a) contained in the epoxy resin (A) is not particularly limited, but the epoxy resin (a) is contained in the epoxy resin (A) in order to exert a more sufficient effect. It is usually necessary to contain 50% by weight or more, preferably 60% by weight or more.

Further, the epoxy resin (A) in the present invention
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. Type epoxy resin, bisphenol F type epoxy resin, halogenated epoxy resin and the like.

In the present invention, the compounding amount of the epoxy resin (A) is usually 4 to 20% by weight, preferably 6 to 18% by weight.
Is.

The curing agent (B) in the present invention is not particularly limited as long as it cures by reacting with the epoxy resin (A). Specific examples thereof include phenol novolac resin, cresol novolac resin and bisphenol A.
Phenolic hardeners such as various novolac resins synthesized from resorcinol and formaldehyde, acid anhydrides such as maleic anhydride, phthalic anhydride, pyromellitic dianhydride, and metaphenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, etc. Examples include aromatic amines. Among them, for the semiconductor device encapsulation, a phenolic curing agent is preferably used from the viewpoint of heat resistance, moisture resistance and storability, and two or more curing agents may be used in combination depending on the application.

In the present invention, the content of the curing agent (B) is usually 3 to 15% by weight, preferably 4 to 10% by weight.
Furthermore, the compounding ratio of the epoxy resin (A) and the curing agent (B) is such that the chemical equivalent ratio of (B) to (A) is in the range of 0.7 to 1.3 from the viewpoint of mechanical properties and moisture resistance. Is preferred, and particularly preferably in the range of 0.8 to 1.2.

Further, in the present invention, the epoxy resin (A)
A curing catalyst may be used to accelerate the curing reaction of the curing agent (B). The curing catalyst is not particularly limited as long as it accelerates the curing reaction, and for example, 2-methylimidazole, 2
-Imidazole compounds such as phenylimidazole, 2-phenyl-4-methylimidazole, 2-heptadecylimidazole, triethylamine, benzyldimethylamine, α-methylbenzyldimethylamine, 1,8-
3 such as diazabicyclo (5,4,0) undecene-7
Primary amine compounds, triphenylphosphine, tributylphosphine, tri (p-methylphenyl) phosphine,
Examples thereof include organic phosphine compounds such as tri (nonylphenyl) phosphine, triphenylphosphine / triphenylborate, and tetraphenylphosphine / tetraphenylborate. Among them, organic phosphine compounds are preferable, and triphenylphosphine is particularly preferably used, from the viewpoint of moisture resistance. Two or more kinds of these curing catalysts may be used in combination depending on the use, and the addition amount thereof is preferably in the range of 0.5 to 5 parts by weight with respect to 100 parts by weight of the epoxy resin (A).

The fused silica (C) in the present invention comprises 97 to 60% by weight of crushed fused silica having an average particle size of 10 μm or less and 3 to 40% by weight of spherical fused silica having an average particle size of 4 μm or less. The average particle size is smaller than the average particle size of the crushed fused silica. Where the molten siri
Mosquito is an amorphous material as commonly used in the field of semiconductor encapsulation.
Collectively referred to as silica. The manufacturing method does not matter. Further, the average particle diameter means a particle diameter (median diameter) at which the cumulative weight becomes 50%,
For example, it is a value measured using a laser diffraction type particle size distribution measuring device or the like.

If the average particle diameter of the crushed fused silica exceeds 10 μm, the solder heat resistance becomes insufficient, and if it is 10 μm or less, no particular limitation is imposed, but from the viewpoint of solder heat resistance, 3 μm or more and 10 μm or less. Those having a thickness of 3 μm or more and less than 7 μm are particularly preferably used. Here, the crushed fused silica has an average particle size of 10 μm.
Two or more kinds having different average particle diameters may be used in combination as long as m or less.

The average particle size of the spherical fused silica is 4 μm.
If the value exceeds 4 μm, the solder heat resistance becomes insufficient, and if it is 4 μm or less, no particular limitation is imposed, but in consideration of moldability, a value of 0.01 μm or more and less than 3 μm is preferable,
Those having a thickness of 0.1 μm or more and less than 3 μm are particularly preferably used. Here, spherical fused silica may be used in combination of two or more kinds having different average particle diameters as long as the average particle diameter is 4 μm or less.

In the fused silica (C) of the present invention, it is important that the average particle diameter of the spherical fused silica is smaller than that of the crushed fused silica. If the average particle size of the spherical fused silica is larger than the average particle size of the crushed fused silica, the solder heat resistance is significantly reduced. The average particle size of the spherical fused silica may be smaller than the average particle size of the crushed fused silica, but the average particle size of the spherical fused silica is preferably 2/3 or less of the average particle size of the crushed fused silica, and particularly preferred. Is 1/2 or less.

Further, in the present invention, if the ratio of crushed fused silica to spherical fused silica is not within 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 fused silica (C) is 75 to 90% by weight of the total, and more preferably 77 to 88% by weight. If the ratio of the inorganic filler to the whole is not within the above range, a cured product having excellent solder heat resistance cannot be obtained.

Fused silica (C) contained in the inorganic filler
Although there is no particular limitation on the ratio of the above, in order to exert a more sufficient effect, it is preferable to include the fused silica (C) in the inorganic filler in an amount of usually 80% by weight or more, preferably 90% by weight or more.

Further, the inorganic filler definitive to the present invention, if the fused silica (C) is contained in the inorganic filler in less than 80% by weight and the rest is not particularly limited, preferred examples are crystalline silica , Alumina, magnesia, clay, talc, calcium silicate, titanium oxide, antimony oxide, various ceramics and the like.

In the present invention, it is preferable in terms of reliability that the inorganic filler containing fused silica (C) is surface-treated in advance with a coupling agent such as a silane coupling agent or a titanate coupling agent. As the coupling agent, silane coupling agents such as epoxysilane, aminosilane, mercaptosilane and the like are preferably used.

The epoxy resin composition of the present invention includes a halogenated epoxy resin, a flame retardant such as a halogen compound and a phosphorus compound, a flame retardant aid such as antimony trioxide, a colorant such as carbon black, a silicone rubber and a modified nitrile rubber. , Modified polybutadiene rubber, modified silicone oil and other elastomers, polyethylene and other thermoplastic resins,
A release agent such as a long-chain fatty acid, a metal salt of a long-chain fatty acid, an ester of a long-chain fatty acid, paraffin wax, and modified silicone oil can be optionally added.

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

[0037]

EXAMPLES The present invention will be specifically described below with reference to examples.

Examples 1 to 12 and Comparative Examples 1 to 9 Mixtures shown in Table 1 were mixed at the composition ratios shown in Table 2 (Examples 1 to 12) and Table 3 (Comparative Examples 1 to 9). Blended with. This was melt-kneaded using a twin-screw extruder having a barrel set temperature of 90 ° C., then cooled and pulverized to produce an epoxy resin composition.

[0039]

[Table 1]

[0040]

[Table 2]

[0041]

[Table 3]

Using this epoxy resin composition, the following solder heat resistance test was conducted.

Solder heat resistance test: 80 pin QFP devices (package size: 17 × 17 × 1.7 mm, chip size: 9 × 9 × 0.5 mm), 32 pieces, under the condition of 175 ° C. × 120 seconds using a low pressure transfer molding machine. And molded at 180 ° C. for 5 hours. After humidifying this test device in an atmosphere of 85 ° C./85% RH for a predetermined time,
Dip 16 pieces into a solder bath heated to 260 ° C for 10 seconds,
The remaining 16 devices were immersed in a VPS (vapor phase solder reflow) bath heated to 215 ° C. for 90 seconds, and the devices in which cracks were generated were made defective.

As shown in Table 4, the epoxy resin compositions of the present invention (Examples 1 to 12) have excellent solder heat resistance. On the other hand, in Comparative Example 2 in which the content of the epoxy resin (a) is outside the range of the present invention, the solder heat resistance is poor, and in Comparative Example 6, the torque at the time of melt-kneading is high, so that a good composition is obtained. It could not be obtained and evaluated. Also,
The average particle diameters of crushed fused silica and spherical fused silica are outside the range of the present invention, respectively. Comparative Examples 5 and 7, Comparative examples where the ratio of spherical fused silica in fused silica (C) is outside the range of the present invention 3 and Comparative Example 8 and Comparative Example 4 in which the average particle size of the spherical fused silica is larger than the average particle size of the crushed fused silica, the solder heat resistance is poor. Further, Comparative Example 1 in which the ratio of the inorganic filler to the whole is less than the range of the present invention
Comparative Example 9 has poor solder heat resistance and is higher than the range of the present invention.
However, since the torque at the time of melt-kneading was high, a good composition could not be obtained, and evaluation could not be made.

[0045]

[Table 4]

[0046]

[Table 5]

Further, as shown in Table 6, when the humidification condition is further severed, the average particle diameter of the crushed fused silica is 7 μm.
It can be seen that with a composition of m or more, cracks begin to appear in a part of the package, and a composition in which crushed fused silica has an average particle size of less than 7 μm is further excellent in solder heat resistance.

[0048]

[Table 6]

[0049]

EFFECT OF THE INVENTION The epoxy resin composition for semiconductor encapsulation of the present invention is excellent in solder heat resistance for semiconductor encapsulation by using a specific epoxy resin and fused silica composed of a specific particle size and shape. Have sex.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number for FI Technical indication H01L 23/31 (56) Reference JP-A-62-74924 (JP, A) JP-A-64- 87616 (JP, A) JP-A-1-263131 (JP, A) JP-A-2-99552 (JP, A) JP-A-2-99514 (JP, A) JP-A-3-66744 (JP, A)

Claims (1)

[Claims] 1. A resin composition comprising an epoxy resin (A), a curing agent (B), and fused silica (C) as essential components, wherein the epoxy resin (A) has the following general formula I) [Chemical formula 1] (However, R ^{1 to} R ⁸ are selected from a hydrogen atom, a C _{1 to} C ₄ lower alkyl group or a halogen atom, and it is not necessary that all are the same.) An essential component is the epoxy resin (a). And the fused silica (C) has a mean particle size of 10 μm or less.
~ 60 wt% and spherical fused silica having an average particle size of 4 μm or less 3
Consists to 40 wt%, the semiconductor average particle size of the spherical fused silica is 75 to 90 wt% of the inorganic filler is a whole containing less than the average particle size of the crushed fused silica, and fused silica (C) Epoxy resin composition for encapsulation .