JPH06192545A - Resin composition for semiconductor sealing use - Google Patents

Abstract

PURPOSE:To provide a composition excellent in the package crack prevention in its reflowing, thus useful for semiconductor packages, comprising, as the main component, a composition made up of an epoxy resin, phenol novolak resin, curing promoter and inorganic filler, and a specific polyimide resin as a filler. CONSTITUTION:The composition comprising (A) as the main component, a composition made up of (1) a epoxy resin, (2) a phenol novolak resin, (3) a curing promoter (e.g. a tertiary amine, imidazole) and (4) an inorganic filler (e.g. crystalline silica, alumina) and (B) as a second filler, 1-20wt.%, based on the whole amount of the final composition, of a polyimide resin (obtained by reaction between a compound of formula I and a compound of formula II at the molar ratio of 1:1) in the form of spherical particles 20-70mum in mean particle diameter and <=150mum in the maximum particle diameter, having a hollow accounting for 20-80vol.% of the volume of the particle itself inside, with a softening point of 200-240 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for semiconductor encapsulation, and particularly to transistors, ICs, LSs.
The present invention relates to a highly reliable semiconductor encapsulating resin composition for encapsulating a semiconductor such as I by transfer molding.

[0002]

2. Description of the Related Art As a sealing method for semiconductor elements such as transistors, ICs and LSIs, a transfer molding method of epoxy resin has been adopted as a method suitable for low cost and mass production. It is at a level that can be used sufficiently by improvement. However, in the trend of making electronic products lighter, thinner, shorter and smaller, a new mounting method called surface mounting of semiconductor packages was born.
A major problem has arisen in the reliability of epoxy resin-sealed semiconductor products. That is, when the semiconductor package is soldered to the circuit board, after the semiconductor package is temporarily fixed to the circuit board and soldering is performed by reflow processing, a very high temperature condition of about 240 ° C. is added during reflow to the semiconductor package. As a result, the sealed package is damaged by the thermal expansion of the hygroscopic water, a gap is generated at the interface between the silicon pellet and the resin, and a crack is generated in the package itself, which significantly deteriorates the reliability of the semiconductor product.

Conventionally, in order to solve this problem, the epoxy resin is made heat resistant (Japanese Patent Laid-Open No. 168620/1986) or the epoxy resin is given flexibility (Japanese Patent Laid-Open No. 62-62160).
-11850, 62-116654, 62-1281
No. 62,62-136860), but none of them is sufficient and the level of 100% guarantee of the reliability of the semiconductor product after the reflow process cannot be reached.

[0004]

SUMMARY OF THE INVENTION The present invention provides a resin composition for semiconductor encapsulation for preventing reliability deterioration after reflow treatment in surface mounting of such semiconductor products.

[0005]

The present invention provides a semiconductor encapsulating resin composition containing an epoxy resin, a phenol novolac resin, a curing accelerator, and an inorganic filler as main components.
As a filler, a polyimide resin having an average particle diameter of 20 to 70 μm, a maximum particle diameter of 150 μm or less, a spherical shape, a void portion of 20 to 80 vol% of its own volume, and a softening temperature of 200 to 240 ° C. is used as a filler. , 1 to 2 in the total amount of the resin composition
It is a resin composition for semiconductor encapsulation containing 0 wt%.

The epoxy resin used in the present invention may be any one used in ordinary resin compositions for semiconductor encapsulation, and examples thereof include cresol novolac type epoxy, trifunctional epoxy, biphenyl type bifunctional epoxy, bisphenol type epoxy, Examples thereof include brominated epoxy, but are not particularly limited. These epoxy resins may be used alone or in combination. Phenol novolac resin of the curing agent may be used in the usual resin composition for semiconductor encapsulation, for example, phenol novolac type,
Examples thereof include cresol novolac type and modified resins thereof, but are not particularly limited. These may be used alone or in combination.

The curing accelerator may be any one as long as it accelerates the reaction between the epoxy group and the phenolic hydroxyl group, and those generally used in the resin composition for semiconductor encapsulation can be widely used. For example, BDMA and the like. Tertiary amines of
Examples thereof include imidazoles, DBU, organic phosphorus compounds such as triphenylphosphine, and the like, which may be used alone or in combination. Further, examples of the inorganic filler used in the present invention include crystalline silica, fused silica, alumina, calcium carbonate, talc, mica, glass fiber and the like.

The polyimide filler used in the present invention may be either thermoplastic or thermosetting, but is preferably thermosetting with high adhesiveness to epoxy resin and has an average particle size of 20 to 70 μm and a maximum particle size. Is preferably 150μ or less spheres, even if it has a particle size or an irregular shape other than this, although it has the effect of preventing package cracks during reflow treatment, the fluidity during molding is poor, unfilled or wire flow,
There is a problem such as pad shift. The voids inside the polyimide filler are essential to absorb and relax the high-pressure steam gas generated inside the package during the reflow process, and the high-pressure steam gas at about 240 ° C. moves from the epoxy resin to the softened polyimide side. It penetrates at a high speed and reaches the pores inside the polyimide, where it is absorbed and prevents package cracks during reflow.

When the steam gas at a high temperature of about 240 ° C. rapidly diffuses into the pores inside the polyimide filler, the steam gas is cooled by the expansion of the gas and the pressure of the steam gas is lowered, which is effective for preventing package cracks. The volume of pores is required to be 20 to 80 vol%, but preferably 50 to
It is 80 vol%. If it is 80 vol% or more, the strength of the polyimide filler itself becomes weak, and the polyimide filler is destroyed due to the compounding process of the encapsulant and the molding pressure during molding, which is not preferable. The softening temperature of the polyimide filler is 200 to 240.
C. is preferable, and when it is 200.degree. C. or less, it is deformed and destroyed during molding at 165 to 185.degree. C., and when it is 240.degree. C. or more, it does not soften near 240.degree. The addition amount to the resin composition for semiconductor encapsulation is appropriately 1 to 20 wt% in the total amount of the resin composition, 1 wt% or less has no effect, and 20 wt% or more, the linear expansion coefficient of the resin composition. Undesirably increases.

[0010]

EXAMPLES The present invention will be described below with reference to examples. The blending ratio is shown in parts by weight. Example 1 Biphenyl type epoxy resin (oiled shell, YX-4000H, epoxy equivalent 190, softening point 107 ° C) 90 parts by weight Brominated epoxy resin (Nippon Kayaku, BREN, epoxy equivalent 270, softening point 70 ° C) 10 Parts by weight Phenol novolac resin (Sumitomo Dures, PR series, hydroxyl group equivalent 104, softening point 110 ° C) 47 parts by weight Fused silica (Tatsumori RD-8, Denka FB-74 1: 1 blend) 400 parts by weight Polyimide filler A 10 Parts by weight triphenylphosphine 2 parts by weight γ-glycidoxypropyltrimethoxysilane (Nippon Unicar A-187) 4 parts by weight antimony trioxide 10 parts by weight carnauba wax 3 parts by weight Carbon black 2 parts by weight are thoroughly mixed at room temperature. Next, knead using a twin-screw heat roll at 80 to 100 ° C., cool and pulverize Tableted Te to obtain a resin composition for semiconductor encapsulation.

The polyimide filler used in the present invention has the formula (1) and the formula (2):

[0012]

[Chemical 1]

[0013]

[Chemical 2]

The mixture was placed in a reactor at a molar ratio of 1: 1 and 5% by weight of a foaming agent was added to the formula (1), and a mixed solvent of N-methyl-2-pyrrolidone and toluene was used as a reaction solvent.
Dehydration reflux was carried out at 0 ° C. for 5 hours. At this time, the particle size of the polyimide filler was adjusted by adjusting the stirring speed of the reaction liquid to 150 to 500 rpm. After completion of the reaction, the reaction product was collected by filtration, dried in vacuum at 150 ° C.
It heated at 1 degreeC for 1 hour, and obtained the polyimide filler. Table 1 shows the properties of the polyimide fillers A, B, and C. Example 2 In the same manner as in Example 1, the resin composition for semiconductor encapsulation shown in Table 1 was obtained.

Comparative Examples 1 to 3 In the same manner as in Example 1, the resin compositions for semiconductor encapsulation having the compositions shown in Table 1 were obtained. The resin compositions for semiconductor encapsulation of Examples 1 and 2 and Comparative Examples 1 to 3 were prepared using a transfer molding machine.
A test piece for evaluation was obtained by molding at 5 ° C. The evaluation results are shown in Table 2.

Evaluation method Reflow crack resistance: 52 pQF with a simulated element enclosed
Using P (14 × 14 × 2.0 mm, chip 6 × 6 mm), it was judged by the presence or absence of package cracks after the reflow treatment (after the moisture absorption treatment of 168H at 85 ° C. and 85% RH for 168H).

[0017]

[Table 1]

[0018]

[Table 2]

[0019]

The resin composition for semiconductor encapsulation of the present invention is excellent in preventing package cracks at the time of reflow treatment, and is suitable for reflow soldering when a semiconductor package sealed with the composition is mounted on a circuit board. Drying before packaging can be omitted, and a highly reliable package can be obtained.

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Claims (1)

[Claims] 1. A resin composition for encapsulating a semiconductor, which comprises an epoxy resin, a phenol novolac resin, a curing accelerator and an inorganic filler as main components and has a spherical shape with an average particle size of 20 to 70 μm and a maximum particle size of 150 μm or less. In the total amount of the resin composition, 1 to 2 is used as a filler having a polyimide resin having a void portion of 20 to 80 vol% of its own volume inside and a softening temperature of 200 to 240 ° C.
A resin composition for semiconductor encapsulation, which contains 0 wt%.