MANUFACTURE OF CERAMIC MULTILAYER WIRING BOARD

PURPOSE:To easily form a microscopic circuit by plating with nickel-phosphorus and copper the exposed face of an inner conductor layer of alumina ceramic, heat treating it, and then roughing the surface, and further forming a conductor circuit on the surface. CONSTITUTION:An inner conductor layer is formed in alumina ceramic by partly exposing it on the surface by a green method. Then, the exposed face of the layer is successively plated with nickel-phosphorus(Ni-P) and copper(Cu), heat-treated in a weakly reducing atmosphere, the surface of the alumina ceramics is roughed, and a conductor circuit is further formed on the alumina ceramics. The material for forming the layer includes high melting point metal such as tungsten, molybdenum, molybdenum-manganese, etc., and the material for forming the circuit includes, for example, noble metal such as gold, silver, platinum, etc., or base metal such as nickel, copper, etc. The formation of the circuit includes, for example, a plating method, a vacuum depositing method, a sputtering method, etc., and it is desirable to form the circuit by an electroless plating method. The heat treatment is required to be conducted in the weak reducing atmosphere.