Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2000-08-24
2002-11-05
Michl, Paul R. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
Reexamination Certificate
active
06476106
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a polyarylene sulfide resin composition for sealing electronic parts. Precisely, it relates to a polyarylene sulfide (hereinafter often referred to as PAS) resin composition suitable for sealing semiconductors such as diodes, transistors, LSIs, CCD devices, ICs, etc.; as well as capacitors, resistors, coils, micro switches, dip switches, etc.
BACKGROUND ART
Polyarylene sulfide resins are engineering plastics having good heat resistance, good flame resistance and good electric and mechanical properties, and are known to be widely usable in the field of electronic parts, electric parts, etc., especially as sealants for electronic parts (for example, Japanese Patent Laid-Open Nos. 266461/1986, 296062/1986, 150752/1987, 45560/1992, 202245/1993, etc.). In these, however, polyarylene sulfide resins are problematic in that the driving reliability of the devices with parts sealed with them is not good after heat cycles.
In general, electronic parts to be sealed include silicon chips, lead frames and others, and are so fabricated that the lead wires therein are electrically connected with aluminium circuits via bonding wires. Where such electronic parts are sealed with resin such as PAS, generally employed is a method of first inserting silicon chips into a mold, and thereafter feeding resin pellets into a screw-in-line type injection-molding machine or the like, in which the silicon chips are sealed with the resin.
The matters especially important to the materials to be used for sealing electronic parts are PCT (pressure cooker test) and TCT (thermal cycle test). In addition, it is also important that the materials for that purpose have good fluidity and do not cause package breakdown. Sealants with poor fluidity will cause deformation or breakdown of bonding wires while they are applied to electronic parts through injection molding.
Referring to the prior art techniques, no one has as yet obtained sealants for electronic parts that satisfy all such fundamental requirements.
We, the present inventors have made the present invention, taking the problems noted above into consideration. The object of the invention is to provide a PAS resin composition which has good PCT and TCT acceptable quality and good fluidity, naturally having good properties intrinsic to ordinary PAS resin, and which, when used for sealing electronic parts, does not cause deformation of bonding wires and other elements, and does not cause package breakdown as its strength is not lowered. Therefore, the PAS resin composition which the invention is to provide is specifically favorable to materials for sealing electronic parts.
DISCLOSURE OF THE INVENTION
We, the present inventors have assiduously studied, and, as a result, have found that a polyarylene sulfide resin composition comprising specific components can attain the object as above.
Specifically, the invention provides the following:
(1) A polyarylene sulfide resin composition for sealing electronic parts, which comprises (A) from 20 to 35% by weight of a polyarylene sulfide resin, (B) from 60 to 75% by weight of silica, and (C) from 1 to 10% by weight of an elastomer, and further contains (D) from 0.05 to 1.2 parts by weight, relative to 100 parts by weight of the total amount of the components (A), (B) and (C), of an epoxysilane.
(2) A polyarylene sulfide resin composition for sealing electronic parts, which comprises (A) from 20 to 35% by weight of a polyarylene sulfide resin, (B) from 60 to 75% by weight of silica, and (C) from 1 to 10% by weight of an elastomer, and further contains (E) from 0.1 to 3 parts by weight, relative to 100 parts by weight of the total amount of the components (A), (B) and (C), of an epoxy resin.
(3) A polyarylene sulfide resin composition for sealing electronic parts, which comprises (A) from 20 to 35% by weight of a polyarylene sulfide resin, (B) from 60 to 75% by weight of silica, and (C) from 1 to 10% by weight of an elastomer, and further contains (D) from 0.05 to 1.2 parts by weight of an epoxysilane and (E) from 0.1 to 3 parts by weight of an epoxy resin, both relative to 100 parts by weight of the total amount of the components (A), (B) and (C).
(4) The polyarylene sulfide resin composition for sealing electronic parts of any one of (1) to (3), wherein the elastomer (C) is an ethylenic copolymer of ethylene, an alkyl &agr;,&bgr;-unsaturated-carboxylate, and maleic anhydride, with the repetitive units being from 50 to 90% by weight, from 5 to 49% by weight, and from 0.5 to 10% by weight, respectively.
(5) A method for sealing electronic parts with a polyarylene sulfide resin composition, in which the composition comprises (A) from 20 to 35% by weight of a polyarylene sulfide resin, (B) from 60 to 75% by weight of silica, and (C) from 1 to 10% by weight of an elastomer, and further contains (D) from 0.05 to 1.2 parts by weight, relative to 100 parts by weight of the total amount of the components (A), (B) and (C), of an epoxysilane.
(6) A method for sealing electronic parts with a polyarylene sulfide resin composition, in which the composition comprises (A) from 20 to 35% by weight of a polyarylene sulfide resin, (B) from 60 to 75% by weight of silica, and (C) from 1 to 10% by weight of an elastomer, and further contains (E) from 0.1 to 3 parts by weight, relative to 100 parts by weight of the total amount of the components (A), (B) and (C), of an epoxy resin.
(7) A method for sealing electronic parts with a polyarylene sulfide resin composition, in which the composition comprises (A) from 20 to 35% by weight of a polyarylene sulfide resin, (B) from 60 to 75% by weight of silica, and (C) from 1 to 10% by weight of an elastomer, and further contains (D) from 0.05 to 1.2 parts by weight of an epoxysilane and (E) from 0.1 to 3 parts by weight of an epoxy resin, both relative to 100 parts by weight of the total amount of the components (A), (B) and (C).
BEST MODES OF CARRYING OUT THE INVENTION
The invention is described in detail hereinunder.
(A) Polyarylene Sulfide Resin
The polyarylene sulfide (PAS) (A) for use in the invention is a polymer having repetitive units of a structural formula, —Ar—S— wherein Ar indicates an arylene group, in an amount of at least 70 mol %. Typically, it is a polyphenylene sulfide (hereinafter often referred to as PPS) having repetitive units of the following chemical formula (I), in an amount of at least 70 mol %.
wherein R
1
indicates a substituent selected from an alkyl or alkoxy group having at most 6 carbon atoms, a phenyl group, a group of a carboxylic acid or its metal salt, a nitro group, or a halogen atom including fluorine, chlorine and bromine atoms; m indicates an integer of from 0 to 4; and n indicates a degree of polymerization falling between 1.3 and 30.
Depending on the method for producing it, it is known that PAS includes two types, one having a substantially linear molecular structure with neither branches or crosslinks, and the other having a branched or crosslinked molecular structure. Any type of PAS is usable in the invention with no specific limitation.
Preferred PAS for use in the invention is a homopolymer or a copolymer having at least 70 mol %, more preferably at least 80 mol % of repetitive paraphenylene sulfide units. PAS of which the repetitive paraphenylene sulfide unit content is smaller than 70 mol % is unfavorable, as it will lose its intrinsic crystallinity characteristic of crystalline polymer and its mechanical properties will be poor. The comonomer units for the copolymer polyarylene sulfide include, for example, metaphenylene sulfide units, orthophenylene sulfide units, p,p′-diphenyleneketone sulfide units, p,p′-diphenylenesulfone sulfide units, p,p′-biphenylene sulfide units, p,p′-diphenyleneether sulfide units, p,p′-diphenylenemethylene sulfide units, p,p′-diphenylenecumenyl sulfide units, naphthyl sulfide units, etc.
The PAS resin can be obtained in any per-se known method of, for example, polycondensation of a dihaloaromatic compound with a sulfur source in an organic
Kinouchi Satoru
Murakami Tomoyoshi
Suzuki Shigemasa
Tsubokura Yutaka
Idemitsu Petrochemical Co. Ltd.
Michl Paul R.
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