JPH0547964A - Resin composition for semiconductor sealing - Google Patents

Abstract

PURPOSE:To contrive a reduction in the stress of a resin composition for semiconductor sealing use and to improve the heat resistance and moldability of the composition by a method wherein the resin composition is constituted of a silicone modified polymer of a specified composition and a polymaleimide compound of a specified weight ratio as a hardening promotor and an organic filler. CONSTITUTION:2 to 20 parts weight and vicinity of organohydrogen polysiloxane is made to react with 100 parts weight of a prepolymer compound obtained by making a bifunctional epoxy resin A having an epoxy group at either terminal thereof react with a dihydric phenol compound B having an allyl group directly bonded to the upper part of an aromatic ring in the extent of the equivalent ratio of an epoxy group to a phenolic hydroxyl group = 1 to 1.1 to 3.5 to obtain a prepolymer C. 2 to 20 parts weight or vicinity of polysiloxane is made to act with 100 parts weight of a prepolymer compound obtained by making the resin A react with the compound B in the extent of the equivalent ratio of the phenolic hydrogen group to the epoxy group = 1 to 1.1 to 5.0 to obtain a prepolymer D. A polymaleimide compound of 40 to 250 parts weight is added to 100 parts weight of the prepolymers C+D.

Description

Detailed Description of the Invention

[0001]

The present invention relates to heat resistance, crack resistance,
The present invention relates to a resin composition for semiconductor encapsulation having excellent moldability.

[0002]

2. Description of the Related Art Conventionally, in semiconductor devices such as ICs and LSIs, those in which the semiconductor element is molded and sealed with epoxy resin are widely used. As the epoxy resin composition, in particular, a polyfunctional epoxy resin, a phenol novolac resin, a resin composition containing an inorganic filler as a main component is excellent in heat resistance, moldability, and electrical characteristics,
It has become the mainstream of sealing materials.

However, due to technological innovation in the semiconductor field, the degree of integration is improved, the element size is increased, and the aluminum wiring is miniaturized due to higher density, and the package tends to be smaller, lighter, and thinner. Furthermore, with the recent surface mounting of semiconductor devices on substrates, the package itself is exposed to the solder bath temperature, so the shearing stress due to the mismatch of the thermal expansion coefficient at the interface where various materials of the package are joined, Generates internal stress such as tensile stress or compressive stress, shifts in miniaturized aluminum wiring, causes passivation cracks, and moisture in the package expands rapidly to cause cracks in the package. It is a cause of lowering the sex.

For these reasons, the stress of the sealing material is reduced,
Improvement of heat resistance is required as an increasingly important property. From this point of view, epoxy resins having a skeleton improved in heat resistance and stress reduction and their silicone-modified encapsulating materials have been studied, but they are low stress, and have high humidity. High-level heat resistance such as mechanical properties, crack resistance, and heat deterioration resistance was insufficient. In addition, in order to obtain even higher heat resistance, development of a sealing material using a thermosetting polyimide resin has been attempted, but the mechanical strength of the obtained cured product is high despite its high heat resistance. It is low and brittle, and it has not been obtained that it has high elasticity under heat, low elasticity, and excellent crack resistance. Furthermore, since it has lower adhesion to metal than epoxy resin, peeling occurs at the interface between the element or frame and the encapsulation material during molding or immersion in a solder bath, resulting in a remarkably poor moisture resistance reliability. is doing.

As one of the attempts to achieve the above object, a composition in which a low stress agent is added to both resins in order to obtain a material having both the characteristics of an epoxy resin and a thermosetting polyimide resin and having a low stress Development of encapsulation materials is in progress. Specifically, a resin composition obtained by adding a polymaleimide compound or a polymaleimide compound, an allyl compound and a low stress agent to a curing system of a polyfunctional epoxy resin and a phenol resin curing agent can be given as an example. However,
Organic phosphine compounds, tertiary amines, and imidazole compounds used as curing agent catalysts for epoxy resins also promote the reaction of maleimide compounds, and the reaction of maleimide compounds proceeds preferentially over the reaction of epoxy resins. The following problems exist. First, the epoxy resin component and low-stress agent component, which react slowly during molding, bleed to contaminate the surface of the molded product and the mold, and secondly, voids occur because the cured product becomes uneven. However, there are drawbacks such as a decrease in stress, a sufficient reduction in stress, and a lack of mechanical strength.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a resin composition for semiconductor encapsulation, which has low stress, heat resistance, rack resistance, adhesion to metal, and good moldability. is there.

[0007]

According to the present invention, (a) a bifunctional epoxy resin having epoxy groups at both ends and a divalent phenol compound having an allyl group directly bonded to an aromatic ring are prepared for a phenolic hydroxyl group. Allyl group-containing both-end epoxy prepolymer compound 100 obtained by reacting epoxy group equivalent ratio in the range of 1.1 to 3.5
2 to 2 parts by weight of organohydrogenpolysiloxane
20 parts by weight of a silicone-modified prepolymer which has been subjected to an addition reaction. (B) A bifunctional epoxy resin having epoxy groups at both ends and a divalent phenol compound having an allyl group directly bonded to an aromatic ring are used, and the equivalent ratio of the phenolic hydroxyl group to the epoxy group is 1.1 to 5.0. A silicone-modified prepolymer in which 2 to 20 parts by weight of an organohydrogenpolysiloxane is added to 100 parts by weight of an allyl group-containing phenol prepolymer compound obtained by reacting within a range. 40 to 25 with respect to 100 parts by weight of (c) (a) + (b)
0 parts by weight of polymaleimide compound. (D) A curing accelerator (e) A semiconductor encapsulating resin composition comprising an inorganic filler, wherein a maleimide compound and an allyl group in a silicone-modified epoxy component and a curing agent silicone-modified phenol component during molding. Is preferred, and the reaction between the epoxy group and the phenolic hydroxyl group, which are present in a small amount during post cure, is completed,
It is possible to form a uniform and dense cured network.

The present invention will be described in detail below. Examples of the bifunctional epoxy resin having epoxy groups at both ends used in (a) and (b) of the present invention include bisphenol S type epoxy resin, bisphenol F type epoxy resin, 3,
As 3 ', 5,5'-tetramethylbisphenol type epoxy resin or brominated epoxy resin, 3,3', 5,5
Preferred examples include 5'-tetrabromobisphenol type A epoxy resin and the like. In order to secure the flame retardancy of the molded product, it is essential to use a brominated epoxy resin together in a fixed ratio.

On the other hand, the divalent phenol compound having an allyl group used in (a) and (b) of the present invention is obtained by reacting a divalent phenol compound with an allyl halide compound in the presence of an alkali. It is a divalent phenol compound having an allyl group directly bonded to an aromatic ring by Claisen rearrangement. Preferred examples of the dihydric phenol include bisphenol A, bisphenol F, bisphenol S, bisphenol, 3,3 ', 5,5'-tetramethylbiphenol and the like. Specific examples of the allyl halide compound include allyl bromide and allyl chloride. It is usually possible to introduce 1 to 4 allyl groups onto the aromatic ring of phenol depending on the composition ratio when the dihydric phenol compound and the allyl halide compound are reacted.

2 having a bifunctional epoxy resin and an allyl group
In the prepolymerization reaction with the hydric phenol compound, the reaction proceeds by heating without a catalyst, but a catalyst is preferably used. As the catalyst, a known compound used for the reaction of an ordinary epoxy resin with a phenol or a compound such as an imidazole compound, a tertiary amine, an organic phosphorus compound can be used appropriately. When these catalysts are used, the prepolymerization reaction is performed under heating at 80 to 180 ° C. for 30
It can be completed in a minute to 12 hours.

Bifunctional epoxy resin When reacting with a dihydric phenol compound having an allyl group, a prepolymer having epoxy groups at both ends or a prepolymer having phenolic hydroxyl groups at both ends is changed by changing the composition ratio of the two. A polymer can be obtained. In this case, assuming that the number of epoxy groups in the composition is X and the number of phenolic hydroxyl groups is Y, 1.1 ≦ X / in the epoxy-terminated prepolymer of (a) of the present invention.
It should be in the range of Y ≦ 3.5. If X / Y is smaller than this, the molecular weight of the prepolymer becomes too large, and the fluidity when used as a molding material decreases. On the other hand, when X / Y is large, unreacted epoxy resin component containing no allyl group is inevitably present as a low-molecular free component, which causes deterioration of moldability and curability. On the other hand, in the case of the phenolic hydroxyl group-terminated prepolymer of (b) of the present invention, the composition ratio of the two should be in the range of 1.1 ≦ Y / X ≦ 5. If Y / X is smaller than this, the prepolymer molecular weight becomes too large, and conversely, if Y / X is too large, the allyl group-containing dihydric phenol compound remains as a low molecular weight unreacted component and the curability and heat resistance decrease. ..

The structure of the organohydrogenpolysiloxane to be reacted with these prepolymer compounds is not particularly limited as long as it is a polysiloxane having a hydrogen atom directly bonded to a silicon atom. It suffices that at least one hydrogen atom is present in one molecule, and it is located at the terminal or side chain of the molecule. Examples of the substituent bonded to a silicon atom other than a hydrogen atom include a methyl group, an ethyl group, a propyl group, a phenyl group, and a polyoxyalkylene group.

The organohydrogenpolysiloxane and the allyl group in the prepolymer can be subjected to an addition reaction in the presence of platinum or a platinum compound. Examples of platinum or a platinum compound as a catalyst include a complex of chloroplatinic acid and olefin, and platinum supported on a carrier such as platinum black, alumina or silica. Although the addition reaction proceeds even at room temperature, the time can usually be shortened by heating to 50 to 150 ° C. It is also possible to use toluene, xylene, methyl isobutyl ketone, or the like, which is a common solvent for the prepolymer compound and the organohydrogenpolysiloxane. The organohydrogenpolysiloxane is preferably reacted in the range of 2 to 20 parts by weight with respect to the prepolymer. If it is less than this, there is no effect in lowering the stress, while if it is more than this, the strength at the time of heating is reduced, so that package cracking occurs during solder immersion.

The proportion of the component (a) and the component (b) in the composition of the present invention is such that the epoxy group of the silicone-modified prepolymer of the component (a) is relative to the phenolic hydroxyl group of the silicone-modified prepolymer of the component (b). Is preferably 0.8 to 1.2. If it exceeds this range, the heat resistance and moisture resistance of the obtained cured product will decrease. The polymaleimide compound used as the component (c) of the present invention is a compound containing two or more maleimide groups in the molecule.

Specific examples thereof include N, N'-diphenylmethane bismaleimide, N, N'-diphenyl ether bismaleimide, N, N'-diphenylsulfone bismaleimide, N, N'-hexamethylene bismaleimide, aniline formaldehyde. Examples thereof include maleimide compounds of polycondensates. Further, a monomaleimide compound such as N-phenylmaleimide or N- (4-hydroxyphenyl) maleimide may be appropriately used in combination with the above polymaleimide compound.

The optimum ratio of the silicone-modified prepolymer as the component (a) and the component (b) and the polymaleimide compound as the component (c) of the present invention can be appropriately selected depending on the application, desired heat resistance and the like. Generally, the above component (a) and component (b) 1
It is preferable to select the component (c) in the range of 40 to 250 parts by weight with respect to 00 parts by weight. If the amount of component (c) is less than this, the effect of improving heat resistance is not obtained, and if it is more than this, the cured product becomes brittle and the adhesiveness decreases.

The component (a) and / or (b) of the present invention
The silicone-modified prepolymer as the component and the polymaleimide compound as the component (c) can be preliminarily reacted in advance to form a uniform resin. By pre-reacting such a silicone-modified prepolymer with maleimide, compatibility and curability are further improved, and the features of the present invention can be further enhanced.

The curing accelerator of the component (d) obtained by the present invention is exemplified by triphenylphosphine,
Organic phosphine compounds such as tributylphosphine and tri-4-methylphenylphosphine, tertiary such as tributylamine, triethylamine, benzyldimethylamine, trisdimethylaminomethylphenol, 1,8-diazabicyclo (5,4,0) undecene-7 Radicals such as amines, 2-methylimidazole, 2-phenylimidazole, 2-ethyl-4-methylimidazole and other imidazole compounds, benzoyl peroxide, di-t-butyl peroxide, cyclohexanone peroxide, azobisisobutyronitrile, etc. A polymerization initiator etc. are mentioned. These may be used alone or in combination of two or more.

Examples of the inorganic filler as the component (e) used in the present invention include crystalline silica, fused silica, crushed silica, alumina, talc, mica, clay, silicon carbide, silicon nitride, boron nitride and zinc white. Be done. These inorganic fillers are 50-80% with respect to 100 parts by weight of the total resin.
Used in the range of 0 parts by weight. In addition, the characteristics can be improved by appropriately selecting the particle size distribution of the inorganic filler.

The composition of the present invention may include, in addition to those described above, colorants such as carbon black, mold release agents such as carnauba wax and synthetic wax, flame retardants such as antimony trioxide, and γ-glycidoxypropyl, if necessary. A coupling agent such as trimethoxysilane and a rubber component such as silicone rubber and polybutadiene can be added. The semiconductor resin composition of the present invention can be used as a molding material by hot-melt kneading with a general kneading device such as a roll or an extruder and cooling and pulverizing.

The present invention will be shown below with reference to examples.

EXAMPLES Reference Example 1 Bisphenol A type epoxy resin (epoxy equivalent 19
0) 510 parts by weight of 3,3 ′, 5,5′-tetrabromobisphenol A type epoxy resin (epoxy equivalent 40
0) 70 parts by weight, 3,3'-diallyl bisphenol A
220 parts by weight of (hydroxyl equivalent 154) and 1 part by weight of triphenylphosphine were reacted at 120 ° C. for 2 hours to obtain prepolymer A (epoxy equivalent 510) at both epoxy terminals. Next, 2000 parts by weight of toluene and 2 parts by weight of a 2% isopropanol solution of chloroplatinic acid were added to form a uniform solution, and then 80 parts by weight of organohydrogenpolysiloxane having hydrogen atoms at both ends with a degree of polymerization of 30 was added. ℃
The hydrosilylation reaction was continued for 1 hour. After distilling off the solvent toluene under vacuum, 340 parts by weight of N, N′-diphenylmethane bismaleimide was further added at 130 to 140 ° C.
And dissolved to obtain a maleimide-modified prepolymer A. Reference Example 2 Same as Reference Example 1 except that 220 parts by weight of the bisphenol A type epoxy resin of Reference Example 1, 510 parts by weight of 3,3′-diallyl bisphenol A, and 50 parts by weight of organohydrogenpolysiloxane were used. Thus, a maleimide-modified prepolymer B having hydroxyl groups at both ends (hydroxyl group equivalent before modification 400) was obtained. Reference Example 3 220 parts by weight of 3,3 ′, 5,5′-tetramethylbiphenol type epoxy resin (epoxy equivalent 190), 3,
70 parts by weight of 3, ′, 5,5′-tetrapromobisphenol A type epoxy resin, 220 parts by weight of 3,3′-diallylbisphenol A, and 1 part by weight of triphenylphosphine were reacted at 120 ° C. for 2 hours, and both epoxy terminals A prepolymer C (epoxy equivalent of 510) was obtained. Toluene 20
00 parts by weight, 2% isopropanol solution of chloroplatinic acid 2
The hydrosilylation reaction was carried out in the same manner as in Example 1 by using 50 parts by weight of organohydrogenpolysiloxane having a polymerization degree of 30 and hydrogen atoms at both ends, and toluene was distilled off. Further, 800 parts by weight of N, N′-diphenylmethane bismaleimide was dissolved at 130 to 140 ° C. to obtain a maleimide-modified prepolymer C. Reference Example 4 The 3,3 ′, 5,5′-tetramethylbiphenol type epoxy resin of Reference Example 3 was added to 230 parts by weight of 3,3′-diallylbisphenol A, and the organohydrogenpolysiloxane was added to 70 parts by weight. A maleimide-modified prepolymer D having hydroxyl groups at both ends (hydroxyl equivalent of 400 before modification) was obtained in the same manner as in Reference Example 3 except for changing the above.

Examples 1 and 2 and Comparative Examples 1 and 2 The raw materials shown in Table 1 were mixed with a mixer, and the mixture was further heated at 80 to 90 ° C.
After being melt-kneaded for 5 minutes with a twin-screw roll, cooled and pulverized to obtain a sealing resin composition. Next, this was transfer-molded at 190 ° C. for 3 minutes, post-cured at 190 ° C. for 8 hours, and then evaluated for physical properties. Table 1 shows each physical property value.

[0023]

[Table 1]

* 1 Spiral flow A molded product obtained by molding a sample with a spiral flow measuring mold conforming to EMMI-I-66 at 15 g, molding temperature 190 ° C., molding pressure 7.0 MPa, molding time 3 minutes. Length of * 2 Bending strength Tensilon bending measuring machine, span 100 mm, load speed 1
Measured value at 0 mm / min and 260 ° C. * 3 Flexural modulus Tensilon bending measuring machine, span 100 mm, load speed 1
Measured value at 0 mm / min and 260 ° C. * 4 Glass transition temperature coefficient of thermal expansion measuring device, sample size 15 × 3 * 5 Solder heat resistance test Molded product (chip size 36 mm ² , package thickness 2 m
For m), the number of cracks is shown after treatment for 72 hours in water vapor of 85 ° C. and 85% RH, and immersion in a solder bath at 240 ° C. for 10 seconds. * 6 Package appearance Visually judge the appearance of the molded product. * 7 Mold stain Visual judgment of mold stain after 1000 shots.

[0025]

As described above, according to the resin composition for semiconductor encapsulation of the present invention, the introduction of the polymaleimide compound and the modified silicone component improves the glass transition temperature and the strength under heat as compared with the ordinary epoxy resin system. Since it has a low stress property, aluminum wiring displacement, passivation cracks and package cracks do not occur even when immersed in a solder bath. Further, unlike the case where the maleimide compound is added to the first epoxy resin system, the epoxy component and the low stress agent, which cure slowly, do not bleed at the time of molding and contaminate the mold. As is apparent from these, the present composition is useful as a sealing material excellent in low stress resistance, heat resistance, crack resistance, moldability, and reliability.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location C08G 59/40 NKG 8416-4J 59/62 NJS 8416-4J C08L 63/00 NKB 8416-4J 83 / 06 PMU 8319-4J

Claims (1)

[Claims] 1. A bifunctional epoxy resin having epoxy groups at both ends and a dihydric phenol compound having an allyl group directly bonded to an aromatic ring are used in an epoxy resin to epoxy group equivalent ratio of 1. A silicone-modified prepolymer in which 2 to 20 parts by weight of an organohydrogenpolysiloxane is added to 100 parts by weight of an allyl group-containing epoxy prepolymer compound obtained by reacting in the range of 1 to 3.5. (B) The equivalent ratio of the phenolic hydroxyl group to the epoxy group of the bifunctional epoxy resin having epoxy groups at both ends and the divalent phenol compound having an allyl group directly bonded to the aromatic ring is in the range of 1.1 to 5.0. 2 to 20 parts by weight of an organohydrogenpolysiloxane is added to 100 parts by weight of a phenol prepolymer compound having an allyl group at both ends obtained by reacting with a silicone-modified prepolymer. 40 to 25 with respect to 100 parts by weight of (c) (a) + (b)
0 parts by weight of polymaleimide compound. A resin composition for semiconductor encapsulation, comprising (d) a curing accelerator and (e) an inorganic filler.