Abstract: A fibrous substrate is coated with a hydrolyzed aminosilane. The aminosilane is hydrolyzed in an aqueous solution having a pH of 3.4 to 3.7. The substrate is useful for preparing fiber reinforced plastics such as prepreg polyepoxide substrates. Improved adhesion between the fibrous substrate and the polymer is obtained.

Abstract: Woven glass cloth and method of its manufacture suitable for use as a resin-impregnated substrate for printed circuits in which the major dimension or transverse axis of the elliptical warp yarns exceeds a predetermined fraction of that dimension of the fill yarns of the woven cloth. Multi-filament warp yarns are typically subjected to tensile stress during weaving and firing such that the yarn compaction prevents the thorough impregnation by a resin. The result is that voids are maintained along the innermost filaments of the yarn. These voids, when filled with materials other than resin, such as plating solution, ultimately produce circuit failures.

Abstract: Woven glass fiber cloth for printed circuit substrates in which the warp is of plied yarn and the fill is of unplied or twisted yarn to facilitate more thorough polymeric resin impregnation and achieve improved dimensional stability.

Abstract: Method of laminating pluralities of sheets as unitary panels with heat and pressure curable adhesive in which unlaminated, uncured sheet pluralities are alternately stacked in a press lay-up with partially cured or semicured unitary sheet pluralities and the entire layup is subjected to heat and pressure for a time sufficient to partially cure the originally uncured sheet pluralities and bring the interspersed, partially cured sheet pluralities to full cure. Thereafter, the newly partially cured and fully cured units are removed and the partially cured units used alternately with new uncured sheet pluralities. This method obviates the need for planishing plates heretofore used to produce smooth surfaces on metal foil covered core units for printed circuit manufacture.