| 摘要 |
PURPOSE:To obtain a laminated sheet having low dielectric constant, excellent high-frequency and insulating characteristics and being free from delamination and very suitable for a printed circuit board and the like, by laminating a plurality of sheets of resin-impregnated base material obtd. by impregnating a fluororesin fabric whose surface has been roughened by a surface treatment with a resin varnish. CONSTITUTION:A surface of a fabric comprising a fluororesin with an m.p. of 200 deg.C or more, such as trifluorochloroethylene resin, tetrafluoroethylene- hexafluoropropylene copolymer resin, etc., is roughened by treating for about 5-10sec with a surface treatment such as a metallic sodium-contg. tetrahydrofuran. Thereafter the fabric is impregnated with a thermosetting resin varnish such as a polyimide, an epoxy resin, etc., and dried to form a resin-impregnated base material 1. Next, a plurality of sheets of this base material 1 are piled up one on another to prepare a set of said material. Several sets of said material are laid between hot plates with molding plates as an interlayer, and then laminated and integrated by heating and pressing to obtain a laminated sheet. Metallic foils 2 are laid on the uppermost and/or lowermost layers, if necessary, to prepare a metal foil-clad laminate. |
