Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1999-09-22
2002-08-27
Dawson, Robert (Department: 1712)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C428S3550EN, C428S3550EN, C428S347000, C428S352000, C428S3550EP, C438S118000, C156S330000, C156S331500
Reexamination Certificate
active
06440258
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to an adhesive film for semiconductor package. More particularly, the present. invention relates to an adhesive film for semiconductor package which is superior in heat resistance and reliability.
(2) Description of the Prior Art
Various adhesives have generally been used for adhesion of the members of a semiconductor device, such as lead pin, substrate for mounting of semiconductor chip, radiator, semiconductor chip and the like. These adhesives include, for example, an adhesive comprising an epoxy group-terminated modified polyamide resin (JP-A-5-51447); an adhesive comprising an epoxy resin and a polyimide resin having polysiloxane units (JP-A-6-200216); and an adhesive comprising an imide type resin (JP-A-10-135248).
However, these adhesives have respective problems. The adhesive comprising an epoxy group-terminated modified polyamide resin has insufficient heat resistance because the modified polyamide resin used therein has a low glass transition temperature, and shows no sufficient adhesivity particularly to the glossy surface of copper foil. The adhesive comprising an epoxy resin and a polyimide resin having polysiloxane units is insufficient in the adhesivity of polyimide resin and the resistance to; soldering heat. The adhesive comprising an imide type resin has a problem in that it tends to cause cracking in the heat shock test conducted for the semiconductor package obtained.
SUMMARY OF THE INVENTION
The present invention aims at alleviating the problems of the prior art, i.e. inferior heat resistance, adhesivity, resistance to soldering heat and resistance to repeated heating and providing an adhesive film for semiconductor package, superior in reliability.
According to the present invention, there is provided an adhesive film for semiconductor package, which comprises a polycarbodiimide resin, an epoxy resin and an inorganic filler, wherein the polycarbodiimide resin has a polystyrene-reduced number-average molecular weight of 3,000 to 50,000 as measured by gel permeation chromatography, the epoxy resin is contained in an amount of 20 to 150 parts by weight per 100 parts by weight of the polycarbodiimide resin, and the inorganic filler is contained in an amount of 30 to 70% by weight based on the total resin content.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is described in detail below.
The adhesive film for semiconductor package according to the present invention is composed essentially of a polycarbodiimide resin, an epoxy resin and an inorganic filler. As this polycarbodiimide resin, there can be used those produced by various methods. There can be used isocyanate-terminated polycarbodiimides produced fundamentally by the conventional method for producing a polycarbodiimide [U.S.P. 2,941,956; JP-B-47-33,279; J. Org. Chem., 28, 2069-2075 (1963); Chemical Review 1981, Vol. 81, No. 4, pages 619-621], specifically by the carbon dioxide removal and condensation reaction of an organic polyisocyanate.
In the above-mentioned method, as the organic 15 polyisocyanate which is the starting material for synthesizing the polycarbodiimide compound, there can be used, for example, aromatic polyisocyanates, aliphatic polyisocyanates, alicyclic polyisocyanates and mixtures thereof, and specifically, there can be mentioned 1,5-naphthalene diisocyanate, 4,4′-diphenylmethane diisocyanate, 4,4′-diphenyldimethylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, hexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, methylcyclohexane diisocyanate, tetramethyl-xylylene diisocyanate, 2,6-diisopropylphenyl diisocyanate, and 1, 3,5-triisopropylbenzene-2,4-diisocyanate.
Among them, those obtained from at least one aromatic polyisocyanate are preferable as the polycarbodiimide resin to be used in the present invention. Incidentally, the aromatic polyisocyanate refers to an isocyanate having, in the molecule, at least two isocyanate groups bonded directly to the aromatic ring.
As the above-mentioned polycarbodiimide, there can also be used those polycarbodiimides whose terminals are blocked with a compound (e.g. a monoisocyanate) reactive with the terminal isocyanates of polycarbodiimide and whose polymerization degrees are controlled at an appropriate level.
As the monoisocyanate for blocking the terminals of polycarbodiimide to control the polymerization degree thereof, there can be mentioned, for example, phenyl isocyanate, tolylene isocyanate, dimethylphenyl isocyanate, cyclohexyl isocyanate, butyl isocyanate, and naphthyl isocyanate.
As the other compounds reactive with the terminal isocyanates of polycarbodiimide, there can be used, for example, aliphatic compounds, aromatic compounds or alicyclic compounds having -OH group (such as methanol, ethanol, phenol, cyclohexanol, N-methylethanolamine, polyethylene glycol monomethyl ether, polypropylene glycol monomethyl ether and the like), ═NH group (such ad diethylamine, dicyclohexylamine and the like), —NH
2
group (such as butylamine, cyclohexylamine and the like), —COOH group (such as propionic acid, benzoic acid, cyclohexanecarboxylic acid and the like), —SH group (such as ethylmercaptan, allylmercaptan, thiophenol and the like), epoxy group, or the like.
The carbon dioxide removal and condensation reaction of the above organic polyisocyanate proceeds in the presence of a carbodiimidation catalyst. As the carbodiimidation catalyst, there can be used, for example, phosphorene oxides such as 1-phenyl-2-phosphorene-1-oxide, 3-methyl-l-phenyl-2-phosphorene-1-oxide, 1-ethyl-2-phosphorene-1-oxide, 3-methyl-2-phosphorene-1-oxide, 3-phosphorene isomers thereof, and the like. Among them, 3-methyl-1-phenyl-2-phosphorene-1-oxide is suitable from the standpoint of reactivity.
The polycarbodiimide resin used in the present invention has a polystyrene-reduced number-average molecular weight of 3,000 to 50,000, preferably 10,000 to 30,000, and more preferably 15,000 to 25,000, as measured by gel permeation chromatography (GPC) regardless of whether or not the above-mentioned terminal-blocking agent is used. When the number-average molecular weight is smaller than 3,000, no sufficient film-formability or heat resistance can be obtained. When the number-average molecular weight exceeds 50,000, a long period of time is required for the synthesis of polycarbodiimide resin and, in addition, the polycarbodiimide resin varnish obtained has an extremely short pot life (service life). Therefore, such number-average molecular weights are not practical.
As the epoxy resin used in the present invention, there can be mentioned epoxy resins having at least two epoxy groups in the molecule, for example, glycidyl ether type epoxy resins, representatives of which are bisphenol A type epoxy resins, bisphenol F type epoxy resins, phenolic novolac type epoxy resins and cresol novolac type epoxy resins; alicyclic epoxy resins; glycidyl ester type epoxy resins; heterocyclic epoxy resins; and liquid rubber-modified epoxy resins. They are used alone or in admixture of two or more. Preferable are bisphenol A type epoxy resins, bisphenol F type epoxy resins, phenolic novolac type epoxy resins and cresol novolac type epoxy resins. However, the epoxy resins used in the present invention are not limited to them and all generally known epoxy resins may be used.
In the present invention, the proportions of the polycarbodiimide resin and the epoxy resin used are 100 parts by weight for the former and 20 to 150 parts by weight, preferably 40 to 130 parts by weight, more preferably 50 to 100 parts by weight for the latter. When the proportion of the epoxy resin is smaller than 20 parts by weight, the mixture of the two resin shows no improvement in heat resistance. When the proportion of the epoxy resin is larg
Imashiro Yasuo
Ito Takahiko
Nakamura Norimasa
Tomita Hideshi
Dawson Robert
Keehan Christopher M.
Kubovcik & Kubovcik
Nisshinbo Industries Inc.
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