Abstract: A copper-clad laminate of a highly-elastic glass fabric base material/thermosetting resin formed of prepreg obtained by impregnating a glass fabric base material made of a glass woven fabric having a thickness of 25 to 150 ?m, a weight of 15 to 165 g/m2 and a gas permeability of 1 to 20 cm3/cm2/sec. with a thermosetting resin composition and drying it.

Abstract: A copper-clad laminate of a highly-elastic glass fabric base material/thermosetting resin formed of prepreg obtained by impregnating a glass fabric base material made of a glass woven fabric having a thickness of 25 to 150 ?m, a weight of 15 to 165 g/m2 and a gas permeability of 1 to 20 cm3/cm2/sec. with a thermosetting resin composition and drying it.

Abstract: A copper-clad laminate of a highly-elastic glass fabric base material/thermosetting resin formed of prepreg obtained by impregnating a glass fabric base material made of a glass woven fabric having a thickness of 25 to 150 ?m, a weight of 15 to 165 g/m2 and a gas permeability of 1 to 20 cm3/cm2/sec. with a thermosetting resin composition and drying it.

Abstract: A method for preparing a thin copper foil-clad substrate for the manufacture therefrom of circuit boards, which comprises subjecting a copper foil-clad circuit board substrate comprising an electrically insulating support having provided on one or both sides thereof a copper foil having an average thickness of 12 .mu.m or more to etching with an etching solution for copper, the etching being performed such that the whole surface of the copper foil is etched at a predetermined etching rate selected from the range of from 0.01 to 0.3 .mu.m/sec, thereby to reduce the thickness of the copper foil on at least one side of the insulating support to 10 to 80% of its original thickness, and the variation of the thickness of the copper foil remaining after the etching is within .+-.2.0 .mu.m on the basis of a desired thickness.

Abstract: A thermosetting resin composition polyfunctional cyanate ester resin composition comprising:(I) a cyanate ester compound selected from the group consisting of a polyfunctional cyanate ester having at least two cyanate esters in its molecule, a prepolymer of such a cyanate ester and mixtures thereof; and(II) at least one non-branched aromatic compound in an amount of 5-40% by weight of the total resin composition, said aromatic compound having a number-average molecular weight of 178-800, an average number of aromatic nuclei of 2-6, and a boiling point of more than 300.degree. C., and in which the portion having aromatic nuclei of 2-6 constitutes more than 50% is disclosed.