Adhesive clad insulating substrate used for producing printed circuit boards

Claim 1

An insulating substrate having a layer of an adhesive composition comprising (A) a modified phenolic resin produced by addition reacting a p-substituted alkylphenol and at least one of p-phenylphenol and p-cumylphenol with an aldehyde, followed by condensation with a phenol and/or an amine having higher reactivity with the aldehyde than the p-substituted alkylphenol and p-phenylphenol and/or p-cumylphenol, the p-substituted alkylphenol being present in an amount of 0.2 to 0.8 mole per mole of the total phenol components, the aldehyde being reacted in an amount of at least 1.3 moles per mole of the total phenol components in the presence of a basic catalyst and a phenol and/or amine being added to the thus-obtained addition reaction intermediate product in an amount of 0.2 to 15 parts by weight per 100 parts by weight of the intermediate product and being condensed with said intermediate product to provide said modified phenolic resin and (B) acrylonitrile-butadiene rubber on at least one surface of a substrate; the ratio of the component (A) to component (B) being 70/30 to 15/85 in solid weight ratio.