The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 17, 1994
Filed:
Aug. 24, 1992
Toshiharu Takada, Kooriyama, JP;
Eiichiro Saito, Kooriyama, JP;
Matsushita Electric Works, Ltd., Osaka, JP;
Abstract
A method for making a prepreg of an epoxy resin impregnated fiberglass substrate for preparing an electrical laminate provides prolonged shelf life of the prepreg, improved adhesive strength between the prepregs or between a metal foil and the prepreg, and also excellent heat resistance for soldering of the laminate, etc. The method of the present invention comprises preparing a resin mixture of an epoxy resin having at least two epoxy groups, a curing agent consisting of dicyandiamide and a halogenated diaminodiphenylmethane derivative of the formula ##STR1## (wherein R1 stands for a hydrogen atom, or a lower alkyl group, R2 stands for a halogen atom, or a lower alkyl group, each of R3 and R4 stands for a lower alkyl group, a hydrogen or halogen atom, and also at least one of R3 and R4 stands for a halogen atom), and a catalyst for effecting the reaction between the epoxy resin and the curing agent, diluting the resin mixture in a solvent to form a resin varnish, impregnating a fiberglass substrate with the resin varnish, and then drying to partially cure the resin impregnated substrate, so that a B-stage cured prepreg is formed.