Abstract: A base material for the production of printed circuits according to the additive method includes a laminate base made up of laminated-together core sheets impregnated with hardenable resin, and a cover layer made up of a substrate sheet preimpregnated with phenolic resol resin and provided with an adhesive layer of an elastomeric polymer. The preimpregnated substrate sheet is also provided with a further resin impregnation containing a self-crosslinking copolymer of acrylic monomers and up to 30% by weight of a hardenable phenolic resol resin.

Abstract: The inclusion of metal particles finely and essentially statistically distributed in an insulating-material body which can be coated with a metal without use of an electric current is described wherein a solution of a reducible metal compound of a metal of Group VIII or Ib is employed. The solution can be added to a resin impregnating solution for the insulating material or to the adhesive of one or more adhesive layers in the insulating material. The solution of metal preferably contains a small amount of ammonium chloride.

Abstract: A laminated material comprises a substrate material containing resin-impregnated layers, a metal foil disposed on said substrate and an arc-retardant layer arranged between the metal foil and the substrate material. The arc-retardant layer is an arc-retardant, crosslinked heat-stable synthetic resinous material consisting of from about 60 to 100% by weight of a heat-stable resin which is free of aromatic groupings or heterocyclic rings containing at least one heteroatom and conjugated double bonds and which is not converted to a graphite-containing structure upon being thermally decomposed.