Wire bonding to dual metal covered pad surfaces

摘要

Wire bonds are made to palladium coated bonded pads on organic dielectric substrates at temperatures below 200° C. A layer of palladium thicker than 14 micro-inches is covered with a thin flash of gold. Palladium coated over copper pads is protected from copper diffusion by a thin nickel layer positioned between the two. Subsequent baking for 1 hour at 185° C. drives off hydrogen molecules provided the gold is less than 200 Å thick. A bonding wire, preferably of gold is then successfully bonded to the pad using conventional bonding equipment at temperatures below 200° C.