JPH07268072A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To obtain an epoxy resin composition improved in resistance to soldering stress and flow by mixing a specified epoxy resin with an inorganic filler, a phenolic resin curing agent and a cure accelerator. CONSTITUTION:An epoxy resin component containing 50-100wt.%, based on the total epoxy resin amount, epoxy resin of formula I (wherein R1 to R8 are each H, a halogen or an alkyl) is mixed with 70-93wt.% inorganic filler having a content of particles with particle diameters of 0.5wt.% and having a mean particle diameter of 5-15mum, 30-100wt.%, based on the total phenolic resin curing agent amount, flexible phenolic resin curing agent comprising a compound of formula II (wherein (r) is p-xylylene; and (n) is 0-8) and a compound of formula III (wherein R is a residue derived by removing the two phenolic moieties from dicyclopentadienediphenol, terpenephenol, cyclopentadienediphenol or cyclohexanonediphenol; and (n) is 0-8) and a cure accelerator.

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 is excellent in solder stress resistance and fluidity in surface mounting of semiconductor devices.

[0002]

2. Description of the Related Art Conventionally, electronic parts such as diodes, transistors, and integrated circuits have been sealed with thermosetting resin. Especially in integrated circuits, orthocresol novolac epoxy resin, which is excellent in heat resistance and moisture resistance, is a novolac type. An epoxy resin composition cured with a phenol resin is used.
However, in recent years, as the integration of integrated circuits has increased, the size of the chip has gradually increased, and the package is a small and thin flat package surface-mounted from the conventional DIP type.
It has been changed to P, SOJ, PLCC. In particular, when exposed to a high temperature of 200 ° C. or higher in the soldering process, moisture resistance is deteriorated due to cracking of the package and peeling of the chip from the resin.

In order to solve these problems, use of an epoxy resin represented by the formula (1) as an epoxy resin (Japanese Patent Laid-Open No. 64-65116) has been studied. By using the epoxy resin represented by the formula (1), the viscosity of the resin system can be reduced. Therefore, by adding a larger amount of the inorganic filler, it is possible to reduce the thermal expansion and the moisture absorption after the composition is molded, so that the solder stress resistance can be improved. The sexuality was improved. However, due to an increase in the blending ratio of the inorganic filler and a thinner IC package (for example, when the thickness of the package is 0.8 mm, the resin thickness above and below the package is 150 to 250 μm), the particle size distribution of the conventional inorganic filler (maximum With a particle size of 100 to 150 μm and an average particle size of 20 to 30 μm, the formability such as pad shift, unfilling, and gold wire deformation could not be improved.

[0004]

SUMMARY OF THE INVENTION The present invention is extremely excellent in crack resistance when subjected to thermal stress due to rapid temperature change in the soldering process, and has a thickness of 0.8 mm.
It is intended to provide a resin composition excellent in fluidity which can be sufficiently adapted to the following thin packages.

[0005]

The present invention provides an epoxy resin represented by formula (1) (A).

[0006]

[Chemical 4] (In the formula, R _{1 to} R ₈ are the same or different atoms or groups selected from hydrogen, halogen and alkyl groups)

Epoxy resin containing 50 to 100% by weight in the total amount of epoxy resin, (B) particle size of 50 μm or more is 0.5
An inorganic filler containing 70 to 93% by weight of the total amount of the resin composition, the inorganic filler having an average particle diameter of 5 to 15 μm in an amount of not more than 10% by weight, (C) formula (2) and / or formula (3). Flexible phenolic resin curing agent

[0008]

[Chemical 5] (R in the formula is paraxylylene, n = 0 to 8)

[0009]

[Chemical 6] (R in the formula is dicyclopentadiene diphenol obtained by addition reaction of dicyclopentadiene and phenol, terpene diphenol obtained by addition reaction of terpenes and phenol, cyclopentadiene diphenol obtained by addition reaction of cyclopentadiene and phenol, and cyclohexanone and phenol Represents a residue of each of the cyclohexanone diphenols obtained by addition-condensation of each of the two phenol moieties, and one selected from these, n = 0 to 8)

30 to 1 in the total amount of the phenolic resin curing agent
An epoxy resin composition comprising a phenolic resin curing agent (00% by weight) and a curing accelerator (D), which is very excellent in solder stress resistance and fluidity as compared with conventional epoxy resin compositions. Is to have.

The biphenyl type epoxy resin represented by the structure of the formula (1) is a bifunctional epoxy resin having two epoxy groups in one molecule and has a low melt viscosity as compared with the conventional polyfunctional epoxy resin and has a transfer property. Excellent fluidity during molding. Therefore, a large amount of inorganic filler of the composition can be blended, low thermal expansion and low water absorption can be achieved, and an epoxy resin composition having excellent solder stress resistance can be obtained.
By adjusting the amount of the biphenyl type epoxy resin used, solder stress resistance can be maximized. In order to bring out the effect of solder stress resistance,
It is desirable to use the biphenyl type epoxy resin represented by the formula (1) in an amount of 50% by weight or more, preferably 70% by weight or more based on the total amount of the epoxy resin. If it is less than 50% by weight, low thermal expansion and low water absorption cannot be achieved, and the solder stress resistance is insufficient. Further, R _{1 to} R ₈ in the formula are the same or different atoms or groups selected from hydrogen, halogen and alkyl groups, and among these, R _{1 to} R ₄ are methyl groups and R ₅ to
R ₈ is preferably a hydrogen atom. When an epoxy resin other than the biphenyl type epoxy resin represented by the formula (1) is used in combination, the epoxy resin used means all polymers having an epoxy group. For example, it refers to a bisphenol type epoxy resin, a cresol novolac type epoxy resin, a phenol novolac type epoxy resin, a triphenol methane type epoxy resin, a triazine nucleus-containing epoxy resin, or the like.

The inorganic filler used in the present invention has a particle size of 50 μm.
m is 0.5% by weight or less, and the average particle size is 5 to 15
Silica that is μm. The shape may be crushed or spherical, but fused silica is preferable to crystalline silica in terms of the coefficient of thermal expansion. If the silica having a particle size of 50 μm or more exceeds 0.5% by weight, problems such as unfilling and pad shift occur in a thin package (thickness of 1.0 mm or less). On the other hand, if the average particle size is less than 5 μm, the melt viscosity at the time of molding becomes remarkably high and the fluidity decreases, and problems such as unfilling, pad shift and gold wire deformation occur. Further, if it exceeds 15 μm, the productivity of the filler is deteriorated, which is not realistic. The amount of inorganic filler compounded is 7
0 to 93% by weight is preferred. If it is less than 70% by weight, the amount of moisture absorption increases, and the coefficient of thermal expansion is large, so that it cannot withstand thermal stress during mounting. Further, if it exceeds 93% by weight, the fluidity deteriorates and it is not practical.

The phenol resin curing agent represented by the structures of the formulas (2) and (3) is a flexible phenol resin curing agent having a relatively flexible structure at the R portion in the molecular structure, and is a phenol novolac resin. As compared with a curing agent or the like, it is possible to lower the elastic modulus in the vicinity of the soldering processing temperature and improve the adhesive force between the lead frame and the semiconductor chip. Therefore, it is effective in reducing the stress generated at the time of solder impact and preventing the defective peeling from the semiconductor chip or the like. By adjusting the amount of the phenol resin curing agent used, solder stress resistance can be maximized. In order to exert the effect of resistance to solder stress, the flexible phenol resin curing agent represented by the formula (2) or (3) is added in an amount of 30% by weight or more, preferably 50% by weight based on the total amount of the phenol resin curing agent. It is desirable that the content be at least wt%. If the amount used is less than 30% by weight, the elasticity is low and the adhesion to the lead frame, semiconductor chip, etc. is insufficient, and improvement in solder stress resistance cannot be expected. Further, the value of n in the formula needs to be in the range of 0-8. If the value of n exceeds 8, the fluidity at the time of transfer molding tends to decrease, and the moldability tends to deteriorate.
Further, R in the formula (3) is dicyclopentadiene diphenol obtained by addition reaction of dicyclopentadiene and phenol,
Represents a residue of terpene diphenol obtained by addition reaction of terpenes with phenol, cyclopentadiene diphenol obtained by addition reaction of cyclopentadiene with phenol, and cyclohexanone diphenol obtained by addition condensation of cyclohexanone with phenol, excluding two phenolic moieties. , And one of them is selected from the group consisting of dicyclopentadiene diphenol obtained by addition reaction of dicyclopentadiene with phenol and terpene diphenol obtained by addition reaction of terpenes with phenol. The residue excluding the phenol part is preferred. Formulas (2) and (3) may be used alone or in combination. When using other than the flexible phenol resin curing agents represented by the formulas (2) and (3) in combination, phenol novolac resin, cresol novolac resin, dicyclopentadiene modified phenol resin and phenol are used. Examples thereof include copolymers with novolac and / or cresol novolac resin.

The curing accelerator used in the present invention may be any one as long as it accelerates the reaction between an epoxy group and a phenolic hydroxyl group, and those generally used for sealing materials can be widely used. , Tertiary amines such as benzyldimethylamine, imidazoles, organic phosphorus compounds such as diazabicycloundecene, triphenylphosphine, and the like, which may be used alone or in combination. The epoxy resin composition of the present invention, if necessary, a silane coupling agent, silicone oil, brominated epoxy resin, antimony trioxide, flame retardant such as hexabromobenzene, carbon black, colorant such as red iron oxide, natural wax,
A release agent such as a synthetic wax and an additive such as a low stress agent such as rubber may be appropriately mixed. The encapsulating epoxy resin composition of the present invention is an epoxy resin, a curing agent, a curing accelerator,
After the inorganic filler and other additives are sufficiently and uniformly mixed with a mixer or the like, the mixture can be melt-kneaded with a hot roll or a kneader, cooled and pulverized to obtain a molding material.
These molding materials are used to seal electronic or electrical components,
Coating, insulation, etc. can be applied.

The present invention will be described in detail below with reference to examples. The mixing ratio is parts by weight. Examples 1 to 11 and Comparative Examples 1 to 6 The following components were mixed according to the formulation shown in Table 1 to obtain compositions. The following composition 3,3 ′, 5,5′-tetramethylbiphenol diglycidyl ether (melting point 107 ° C., epoxy equivalent 191 g / eq) Orthocresol novolac type epoxy resin (hereinafter EO
(Referred to as CN) (softening point 65 ° C., epoxy equivalent 197 g / eq) curing agent represented by formula (4)

[0016]

[Chemical 7] (Softening point 75 ° C., hydroxyl equivalent 174 g / eq)

A curing agent represented by the formula (5)

[Chemical 8] (Softening point 75 ° C., hydroxyl equivalent 174 g / eq)

Phenolic novolac resin curing agent (hereinafter P
N) (Softening point 104 ° C., hydroxyl equivalent 103 g / eq) Fused silica powder * 2 Spherical fused silica Average particle size 5 μm, particle size 50 μm
0% by weight or more * 3 Ground silica / spherical fused silica = 20% by weight / 8
0% by weight, average particle size 10 μm, particle size 50 μm or more 0% by weight * 4 Ground silica / spherical fused silica = 20% by weight / 8
0% by weight, average particle size 10 μm, particle size 50 μm or more 10
% By weight * 5 pulverized silica / spherical fused silica = 5% by weight / 9
5% by weight, average particle size 1 μm, particle size 50 μm or more 0% by weight Triphenylphosphine (hereinafter referred to as TPP) carbon black Carnauba wax is mixed at room temperature with a mixer, roll-kneaded at 80 to 90 ° C., cooled and ground. A molding material was obtained. The obtained molding material is made into a tablet, and 1
80pQ of 6mm × 6mm chip for solder crack test under the condition of 75 ° C, 70kg / cm ² , 120 seconds
It was sealed in FP (thickness 0.8 mm). The following solder crack test and internal voids for the sealed test element,
Unfilled, pad shift, and unfilled were observed. The evaluation results are shown in Tables 1 and 2.

Evaluation method Sparral flow: Measured at 175 ° C. and 70 kg / cm ² using a mold according to EMMI-I-66. Internal void: A package molded for a solder crack test was cross-section polished and observed. Unfilled: The molded package is visually confirmed. Pat shift: The molded package was subjected to cross-sectional polishing, and a pad having a shift of 0.25 mm or more was regarded as defective. Solder crack test: sealed test element at 85 ° C, 8
168 hr and 336 hr treatment in an environment of 5% RH,
Then, after IR reflow (240 ° C, 10 seconds) treatment,
External cracks were observed under a microscope.

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

According to the present invention, it is possible to obtain an epoxy resin composition which has both solder stress resistance in a thin package (thickness of 0.8 mm or less) and moldability which cannot be obtained by conventional techniques. Out.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C08L 63/00 NJW H01L 23/29 23/31

Claims (2)

[Claims] 1. An epoxy resin represented by the formula (1) (A): An epoxy resin containing 50 to 100% by weight in the total amount of epoxy resin (wherein R _{1 to} R ₈ are the same or different atoms or groups selected from hydrogen, halogen and alkyl groups), (B) particle size An inorganic filler containing 70 to 93% by weight in the total amount of the resin composition of an inorganic filler having an average particle diameter of 5 to 15 μm and 50% or more and 0.5% by weight or less.
(C) Flexible phenol resin curing agent represented by formula (2) and / or formula (3) (R in the formula is paraxylylene, n = 0 to 8) (R in the formula is dicyclopentadiene diphenol obtained by addition reaction of dicyclopentadiene and phenol, terpene diphenol obtained by addition reaction of terpenes and phenol, cyclopentadiene diphenol obtained by addition reaction of cyclopentadiene and phenol, and cyclohexanone and phenol Represents a residue of each of the cyclohexanone diphenols that is condensation-condensed with each of the two phenol moieties, and one of these is selected, n = 0 to 8), in an amount of 30 to 30% of the total amount of the phenol resin curing agent. An epoxy resin composition comprising 100% by weight of a phenol resin curing agent and (D) a curing accelerator. 2. The epoxy resin composition according to claim 1, wherein R in the formula (3) is a residue of terpene diphenol obtained by addition reaction of terpenes with phenol, excluding two phenol moieties.