Improvements relating to methods for forming conductive pads on a circuit board by coating with metals

摘要

Conductive pads are formed on micro-circuit wafers 10 of e.g. a ceramic (alumina or beryllia), glass or a polymeric material, by mounting the wafers between masks 12, 14, mounting the assembly in a rotating wheel and depositing metal by either sputtering or vapour deposition from sources 16, 18. A first layer may be Cr, Ti, Zr, Mn, Ta or Co and a second layer Au, Cu, Ni, Ag, Ta or Al. As the wheel rotates, a stationary chain 34 causes the assembly of wafers 10 to be rotated about their own axes. Masks are then arranged to expose all but the sides, and a layer of Al deposited at 42, Fig. 4, which is then oxidized electrolytically using e.g. 10% H2SO4 solution as electrolyte. Electric contact is made with the Al layer, e.g. by breaking through the oxide layer, and copper or nickel is electrolytically deposited on the terminations previously deposited. The aluminium and its oxide coating are removed by e.g. immersion in an alkaline solution. The terminations so formed are tapered.