JPS601220A - Epoxy resin composition for semiconductor sealing - Google Patents

Abstract

PURPOSE:The titled composition of low stress, high heat shock resistance and excellent high-temperature properties, comprising a polyepoxy compound, a styrene block copolymer, a liquid rubber, a curing agent, and an inorganic filler. CONSTITUTION:60-80wt% inorganic filler (e.g., alumina) is added to a composition comprising 100pts.wt. polyepoxy compound (e.g., bisphenol A-derived epoxy resin) having a Cl ion content <=10ppm and a hydrolyzable chlorine content <=0.1wt%, 2-20pts.wt. styrene block copolymer (e.g., styrene/butadiene block copolymer), 2-30pts.wt. liquid rubber (e.g., low-MW 1,2-polybutadiene), and a curing agent for the polyepoxy compound (e.g., novolak phenol resin having a content of components soluble in water at normal temperature of 3wt% or below).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides epoxy resin compositions, particularly for diodes, transistors, ICs! The present invention relates to an epoxy resin composition for semiconductor encapsulation, which is used for encapsulating so-called semiconductor devices such as LSIs, and has low strain stress, high heat shock resistance, and excellent high temperature characteristics.

In recent years, in the field of electronic components, there has been a trend toward smaller size and lighter weight, higher density of elements, larger size, and multifunctionality through composites and the like. For such electronic components, especially semiconductors, a sealing method using sealing resin is widely used.
This sealing resin is also required to improve various defects.

Conventionally, materials such as epixy-based, silicone-based, phenol-based, and diallylphthalate-based resins have been used as semiconductor encapsulation resins. Among them, epoxy resin molding materials that use phenolic novolak resin as a hardening agent are
It is superior to other sealing resins and is widely used because it has a harmonious relationship between adhesion to the object to be sealed and electrical properties.

Resin sealing of semiconductor elements is generally done using transfer molding, but in this method, there is a considerable difference in thermal expansion coefficient between the element made of an inorganic material and the resin, so pressure is applied during or after molding. There is a problem in that large strain stress tends to occur when subjected to sudden temperature changes. In particular, conventional epoxy resin molding materials have a large strain stress, and if the large element pellet is directly molded without applying a flexible protective coating, the element pellet may crack or bonding wires may be cut. was seen. Furthermore, in ultra-thin resin-sealed semiconductors that have recently been designed to be smaller and lighter, this strain stress causes cracks in the sealing resin itself, causing the problem that it no longer performs its sealing function. As a countermeasure to these problems, it has been desired to develop a resin that has low strain stress and does not cause cracks. Methods for reducing the strain stress of the sealing resin include (2) a method of lowering the coefficient of thermal expansion of the il+ resin to approximate that of an inorganic material, and (2) a method of lowering the elastic modulus.

The former (1) is generally achieved by adding an inorganic filler with a small coefficient of thermal expansion to the resin. Although this reduces the coefficient of linear expansion of the sealing resin, it increases the modulus of elasticity, causing strain. Stress reduction is not sufficient. On the other hand, the latter (2)
This is achieved by adding a flexibility imparting agent to the resin. Conventionally, flexibility-imparting agents include long-chain bis-ethoxy, such as diglyndyl ether and polypropylene glycol diglycyl ether, for bisphenol with long side chains,
Recently, there are carboxyl groups, amino groups, etc. at the terminal end.
Examples include reactive liquid rubbers such as low molecular weight polybutadiene and its copolymers. However, if these flexibility imparting agents are added until the strain stress becomes sufficiently small, the mechanical strength and glass transition point will be significantly lowered, causing major problems in heat shock resistance and high temperature properties. They have previously developed a resin composition that is effective for low strain stress, etc., containing a polyfunctional epoxy compound, a styrene block copolymer, a poxy (TS compound) curing agent, and an inorganic filler as main components. Molding material (patent application 1986-186)
No. 518) was proposed. The present invention has discovered that by adding liquid rubber to this material, the low strain stress, high heat stain resistance, and high temperature properties can be further improved.

That is, the present invention provides (a) polyfunctional epoxy compound 1
An epoxy resin composition for semiconductor encapsulation, characterized in that the main components are (b) a styrene block copolymer, (C) a liquid comb, (d) an epoxy compound curing agent, and (e) an inorganic filler. be.

The present invention will be explained in detail below.

In the present invention, (a) polyfunctional epoxy compounds include glycidyl ether type epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins such as bisphenol A type epoxy resins, phenol novolac type epoxy resins, and cresol novolac type epoxy resins. , linear aliphatic epoxy resins, alicyclic epoxy resins, heterocyclic epoxy resins, and halogenated epoxy resins, including -epoxy compounds having two or more epoxy groups in the molecule. In addition, these epoxy compounds may be used alone or in a mixed system of two or more, and in consideration of corrosion resistance, the content of chlorine ions is 10 ppm.
Hereinafter, the content of hydrolyzable chlorine is preferably 0.1% by weight or less.

Next, the (b) styrenic block copolymer (hereinafter referred to as block copolymer) in the present invention is an essential component for obtaining a low stress molded article, and the block copolymer is composed of styrene, α-methylstyrene, , aliphatic polymer blocks such as vinyltoluene, divinylbenzene, and t-butylstyrene imprene, or hydrogenated ethylene-butylene, and a chain with a 34 reamer block, and may also have a teno-unit structure in the chain. do not have. These block copolymers are so-called linear block copolymers, one star block copolymers, double scoop block copolymers, etc., and for example, (A-B
)nA, (A-B.)n-(A-B)nX% (A-E
) nXAm (n% m: integer, A: styrene, α
- A polymer block having a benzene nucleus such as methylstyrene or vinylbenzene, B: butadiene), an aliphatic polymer block such as isoprene, or a hydrogenated ethylene-benzene polymer block, and an X-niblock chain are mutually cut.

(coupling agent unit), but the form is not particularly limited. Further, the block copolymer can be used alone or in a mixed system of two or more kinds, and the amount of the block copolymer is not particularly limited.

The amount of the block copolymer added is preferably 2 to 20 parts by weight, more preferably 5 to 15 parts by weight, based on 100 parts by weight of the epoxy compound. If the amount is less than 2 parts by weight, the effect of adding the block copolymer will not appear, and the reduction in strain stress and the improvement in heat shock resistance will not be seen sufficiently. If the amount exceeds 20 parts by weight, fluidity decreases and air entrainment increases, causing bleed matter to appear on the surface of the molded product, 1 and resulting in poor moldability such as leakage of the sealed contents. The above-mentioned block copolymers are specifically manufactured by Shell International (Califlex TR series and Kraton G series), Asahi Kasei Corporation (Tuffrene), Philips (K resin and Tulprene-T), and Denki Kagaku Kogyo (Tuffrene). Clearen) etc.

In the present invention, the liquid rubber (c) has a low molecular weight of 1
, 2 polybutadiene, 1,3 polybutadiene, ■.

4 polybutadiene, butadiene-based low molecular weight polymers such as butadiene-styrene copolymer and butadiene-acrylonitrile copolymer, isoprene-based low molecular weight polymers such as low molecular weight polyisoprene and low molecular weight depolymerized rubber of natural rubber, and liquid chloroprene. Any liquid rubber such as rubber, liquid silicone rubber, liquid polysulfide, etc. can be used, and one type or a mixture of two or more types can also be used.

These liquid rubbers preferably have reactive groups such as epoxy groups, hydroxyl groups, amino groups, thiol groups, carboxyl groups, and vinyl groups at their terminal ends.

The amount of liquid rubber added is (a) polyfunctional epoxy compound 1
The amount is preferably 2 to 30 parts by weight, more preferably 5 to 20 parts by weight. Less than 2 parts by weight,
The effect of reducing strain stress and improving heat shock resistance does not appear, so it is added in excess of 30 parts by weight. This may result in poor moldability, such as a decrease in fluidity, the formation of many voids in the molded product, or the appearance of bleed substances on the surface of the molded product, as well as a decrease in the mechanical strength of the molded product, and the formation of a large number of voids in the molded product. This has disadvantages such as lowering the adhesiveness of the material, resulting in poor moisture resistance.

In the present invention, the total amount of component (b) styrenic block copolymer and component (c) liquid rubber is suitably 5 to 40 parts by weight based on 100 parts by weight of component (a) polyfunctional epoxy compound.

Examples of the curing agent for the epoxy compound (d) in the present invention include phenol resins, polyhydric phenol compounds, acid anhydrides or amines, and polysulfide resins. To give more specific examples, examples of phenolic resins and polyhydric phenol compounds include novolak type phenolic resins such as phenol novolac resin, cresyl noholac resin, tert-butylphenol novolac resin, resol type phenolic resin, and bisphenol A. be. Examples of acid anhydrides include phthalic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, pyromellitic anhydride, dodecylsuccinic anhydride, diethylenetriamine, triethylenetetramine, diethylaminepropylamine, Examples of amines include N-aminoethylpiperazine metaxylene diamine and 3,9-bis(3-aminopropyl)-2,4,8,10-tetraoxaspiro(5,5)undecane.

Among the curing agents mentioned above, novolak type phenolic resin is
It is most preferred as a curing agent for epoxy compounds, and its softening point is in the range of 60 to 100°C, and the content of water-soluble components at normal humidity is 3% by weight or less, in order to prevent toxicity as a molding material or harden it. Desirable for its moisture resistance.

Furthermore, the inorganic filler (e) which is another essential component of the present invention includes, for example, zircon oxide, alpha quartz, fused silica, clay, alumina, aluminum hydroxide, calcium carbonate, glass, asbestos, whiskers, gypsum, Examples include magnesite, mica, kaolin, Merck, graphite, cement, iron carbonyl, ferrite, molybdenum disulfide, zinc white, titanium white, carbon black, silica sand, and wollastonite, and two or more of these can also be used in combination. .

The amount of the inorganic filler added is preferably 60 to 80% by weight based on the total weight of all components. %, the fluidity of the material deteriorates significantly and it becomes impossible to mold it.

Moreover, various catalysts can be added to the epoxy resin composition for semiconductor encapsulation of the present invention for the purpose of accelerating the curing reaction of the polyfunctional epoxy compound when the temperature reaches a predetermined temperature. For example, imidazole, 2-methylimidazole,
2-ethylimidazole S1. Imidazoles such as 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, 2-phenylimidazole, triethylamine 1 diethylenetriamine, triethylenetetramine, N-aminoethylhyherazine, Metaxylene diamine, amine compounds such as 3,9-bis(3-aminopropyl)-2,4,8,10-tetraoxaspiro(5,5)undeca7, or complex compounds consisting of triethylamine and BF; Examples include organic phosphine compounds such as triphenylphosphine, tributylphosphine, methyldiphenylphosphine, butylphenylphosphine, dimethylphosphine, phenylphosphine, and octylphosphine, as well as thiazoles. These curing catalysts may be used alone or in combination of two or more.

Furthermore, in the present invention, a mold release agent, a coloring agent, a flame retardant, a silica/coupling agent, etc. may be added and blended as appropriate depending on the purpose of use. Examples of mold release agents include natural waxes, synthetic waxes, linear fatty acids and their metal salts, acid amides, esters, or paraffin, and examples of flame retardants include brominated epoxy resins, chlorinated paraffins, Fromotoluene, hexabromobenzene 1 It is obtained by uniformly kneading each component in a mixing device such as a roll or a kneader, and the specific operation method such as the mixing order is a method that allows each component to be mixed uniformly. There are no particular restrictions.

As explained above, the present invention uses (a) a polyfunctional epoxy compound, (b) a styrenic block copolymer, (C) a liquid rubber, (d) a curing agent for the epoxy compound, and (e) an inorganic filler in an appropriate manner. By uniformly mixing them in a ratio of 1 to 1, the composition produces a molded product with low strain stress and excellent mechanical strength and moldability, and when a semiconductor element is encapsulated, there is no cracking of the pellet, and heat shock resistance is 1. It has a remarkable effect on moisture resistance.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these in any way.

Examples 1-3, Comparative Examples 1-4 Epoxy 1220 cresol novolac epoxy tree, rtx (manufactured by Nippon Kayaku Co., Ltd., trade name BOON, 10
3) Brominated novolak epoxy resin with 85 parts by weight and epoxy equivalent of 280 (manufactured by Nippon Kayaku Co., Ltd., trade name: BRENS)
) 15 parts by weight, phenol novolak resin (manufactured by Gunei Chemical Co., Ltd.) 50 parts by weight, 2-undecylimidazole 2
parts by weight, 2 parts by weight of carnauba wax, 3 parts by weight of r-glycidoxypropyltrimethoxysilane, 1 part by weight of carbon black, 10 parts by weight of antimony trioxide, fused silica (manufactured by Denki Kagaku Kogyo Co., Ltd., Denka fused silica, FS-9
) (Examples 1 to 3S Comparative Examples 1 to 3: 414 parts by weight, Comparative Example 4: 374 parts by weight). A composition was prepared by adding and blending a styrenic block copolymer and liquid rubber (parts by weight), mixing with a mixer, mixing with a heating roll, cooling and pulverizing.

The properties of the epoxy resin compositions obtained in Examples 1 to 3 and Comparative Examples 1 to 4 are shown in Table 1.

Note that each characteristic in Table 1 is a value obtained by measurement by the following method.

Spiral flow EMMI -1-66 175°C, 70kq□2
．． Measurement was carried out under the condition of 2 minutes.

Appearance of molded product The surface condition of the cured product immediately after transfer molding was observed under the conditions of 175° C. and 70 μm 2.2 minutes.

Stress measurement piezoresistive element (a piezoresistor whose resistance value changes depending on stress is molded into a semiconductor chip): i DIP
Set in the frame of type IC, 175℃, 70 kg/
Each composition was transfer molded under molding conditions of 1 m2.2 minutes, post-cured at 170° C. for 4 hours, and after cooling, strain stress was measured using the above element.

Heat shock resistance measurement island size 4 x 7.5 mm 16 pin l0
IJ-deframes were transfer-molded using each composition at 175°C and 70kf/cm2.2 min.
The molded product was repeatedly immersed in the liquid for 30 seconds each time, and the incidence of cracks on the surface of the molded product was examined. The crack occurrence rate indicates the percentage of the number of cracked chips among 10 IC chips.

Moisture resistance test A silicon chip equipped with an aluminum wire was set in the frame of a 16-pin DIP type IC, and each composition was coated and molded using a transfer molding method under molding conditions of 175°C for 2 minutes to obtain a test molded body. was manufactured. Humidity resistance test (PCT) to examine the corrosion of the aluminum wire in 100% steam at 121°C in the thus produced molded body
・Humidity test (bias PC'l') to check corrosion of aluminum wire by applying 20V (DC) voltage under the same environment
) to evaluate moisture resistance and corrosion resistance. In the table, the number of defective products among 100 molded products after each time period is shown as the defective rate.

Styrenic block polymer (1): Styrene-butadiene block copolymer (butadiene content 70% by weight) manufactured by Denki Kagaku Kogyo Co., Ltd. 1 trade name, ST-1702 Styrenic block polymer (2): Styrene-ethylene・Butylene block copolymer (ethylene-butylene content 86% by weight) manufactured by Shell International, trade name, Kraton G1657 Liquid rubber (1): terminal carboxyl butadiene-acrylonitrile copolymer (acrylonitrile content 18 mol%) Gutudoritsu 1 1 product name manufactured by Chi Chemical Co., Ltd. Hiker 0'l'BN
+1300X8 Liquid rubber (2): Epoxidized terminal 1.4 Polybutadiene 1 Manufactured by Idemitsu Petrochemical Industry Co., Ltd., trade name, Poly bd-R-45EFT Addition and blending of the styrenic block copolymer of the present invention and liquid rubber The molded products obtained from the epoxy resin compositions obtained from the above-mentioned block copolymer or the liquid rubber have better stress and heat shock resistance than those obtained from the epoxy resin compositions containing the block copolymer or the liquid rubber alone or not at all. It was found to be excellent in all physical properties, including moisture resistance and corrosion resistance.

Examples 4 to 7, Comparative Examples 5 to 8 Cresol novolak epoxy resin with epoxy equivalent of 220 (1 trade name manufactured by Nippon Kayaku Co., Ltd., EOON%103S
), a brominated novolac epoxy resin (manufactured by Nippon Kayaku Co., Ltd., trade name, BRBNS) with an epoxy equivalent of 280, and liquid rubber were placed in a container equipped with a stirring device at the proportions shown in Table 2 and heated at 150°C. The mixture was melt-mixed for 3 hours to fully disperse the liquid rubber in the epoxy resin. However, the rubber-dispersed epoxy resin turned into a gel after 1 hour of stirring and became difficult to stir, so it was immediately taken out and cooled before use.

Table 2: Liquid rubber (3) Bi-terminal carboxyl 1,2-polybutadiene manufactured by Nippon Soda Co., Ltd., trade name Nl5SO-PB
--1000 Contains 1 epoxy resin for each of the above rubber-dispersed epoxy resins
Per 00 parts by weight, 5-0 parts by weight of phenol novolak resin, 1 part by weight of triphenylphosphine, 2 parts by weight of carnauba wax, 3 parts by weight of γ-glycidoxypropyltrimethoxysilane, 21 parts by weight of carbon furano, 10 parts by weight of antimony trioxide. parts by weight, and fused silica (manufactured by Denki Kagaku Kogyo Co., Ltd., Denka Fused Warp, FS-90) (Example 4 is 4
05 parts by weight 15 is 416 parts by weight, 6.7 is 438 parts by weight, Comparative Example 5.8 is 438 parts by weight, 6 is 372 parts by weight, and 19.7 is 394 parts by weight). A styrenic block copolymer was further added to the composition in the parts by weight shown in Table 3, the mixture was powder-mixed using a mixer, and further kneaded using heated rolls, cooled, and pulverized to prepare a composition.

The properties of the epoxy resin compositions obtained in Examples 4 to 7 and Comparative Examples 5 to 8 are shown in Table 3.

Note that each characteristic was measured using the same method as in Table 1.

As is clear from the above Examples and Comparative Examples, the epoxy resin composition according to the present invention has excellent properties for semiconductor encapsulation.

Reference Example Table 4 shows the results of stress measurements of the epoxy resin compositions obtained in Examples 1 to 3 and Comparative Examples 1 to 4 by the steel ring method.

Steel ring method: A strain gauge was pasted on the inside of an iron cylinder (outer diameter: 20mm, thickness: 1mm, height: 20mm), and the outside was molded with resin. The thickness of the resin is 10 mm.

The stress generated in the circumferential direction at 25° C. after molding at 170° C. was calculated from the amount of deformation of the iron cylinder.・Table 4 Note that as a method for measuring strain and stress, the piezoresistive element method of the present invention measures through the same molding method such as semiconductor sealing, so it can evaluate strain and stress closer to reality than the steel 1Nong method. .

Applicant Denki Kagaku Kogyo Co., Ltd. Agent Yutaka 1) Proceeding Amendment August 19, 1981 Kazuo Wakasugi, Commissioner of the Patent Office1, Indication of Case Patent Application No. 107894 No. 1982, Invention Name: Epoxy Resin Composition for Semiconductor Encapsulation 3, Relationship with the Amended Person Case/Patent Applicant: 1-4-1 Yurakucho, Chiyoda-ku, Tokyo (328) Denki Kagaku Kogyo Co., Ltd. Representative: Akira Shinohara 4, Representative Mr. Rito, Room 204, Sanshin Building, 1-4-1 Yurakucho, Chiyoda-ku, Tokyo Telephone: 501-21385 Column 6 of "Detailed Description of the Invention" of the specification subject to amendment Street correction ■: Yes.

l) Specification Section, page 14, line 1 Correct rFS-9J to rFS-90J.

2) // Page 18, line 4 r 5TR-1?02J is ``Denka 5TR-1702J
4. :correct.

Claims (1)

[Scope of Claims] (a) A polyfunctional epoxy compound (b) A styrene block copolymer (C) A liquid compound (d) A curing agent for an epoxy compound (e) An inorganic filler as the main component Characteristic epoxy resin composition for semiconductor encapsulation.