Process in the production of a multilayer printed board

Claim 1

A process for the production of a multilayer printed board with plated-through holes for electronic use having a desired conductive pattern in each layer with increased adhesion between the layers, comprising: a. forming a plating resist layer in the shape of a negative of the desired conductive pattern on the inner surfaces of a desired number of insulating bases having both sides coated with an unpatterned metal layer of copper or a copper alloy to leave remaining visible parts forming the desired conductive pattern, b. electroplating said remaining visible parts of the metal coated layers with a thin, rough, adhesion-promoting metal layer comprising at least one metal selected from the group consisting of copper, zinc, nickel, tin, and alloys thereof, and in the event copper, zinc or an alloy thereof is electroplated, then further electroplating on top of this adhesion-promoting layer an etch resist layer of nickel, tin or an alloy thereof, c. removing the negative plating resist layer applied in step (a), d. etching away the parts of the metal layer uncovered by step (c), e. placing between the insulating bases provided with the conductive patterns at least one layer of plastic or a fiber material impregnated with partially cured or hardened plastic to form a composite, f. laminating under heat and pressure the composite article of step (e) to form a multilayer printed board having an extremely good adhesion between the metal patterns and the plastic layers, g. producing holes in the multilayer printed board in a desired pattern, and h. plating through the holes and providing the surface layers on the multilayer printed board with a desired conductive pattern.