PURPOSE: To improve silver migration resistance and galvanic corrosion resistance by piling prepregs formed by impregnating a paper base material with a thermosetting resin incorporated with a specified compd. and drying the impregnated material and molding the prepregs by heating and pressing.
CONSTITUTION: A necessary number of sheets of prepregs obtd. by impregnating a paper base material with a thermosetting resin incorporated with 0.1-5.0% compd. of formula 1 (wherein R1, R2 and R3 are each H, OH CH3, CH3CH2, (CH3)2CH or (CH3)3C) are piled and molded by heating and pressing to obtain a laminated sheet and in addition, a copper foil is piled thereon to obtain a copper-clad laminated sheet. As the thermosetting resin, phenol resins, drying oil phenol resins, epoxy resins, unsatd. polyester resins etc., are used and as the paper base materials, kraft papers and linter papers are used. As the incorporated compd. of formula 1 has carboxyl groups and amide groups, it exhibits a property catching metal ions such as copper ions and silver ions as chelate rings. Especially, when R1 and R3 are (CH3)2C and R2 is OH, a good result is obtd.
YOKOTA MITSUO
NAKAMURA YOSHIHIRO
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