use of nickel and copper is suitable for soldering and electrical conductivity nickel is a good diffusion barrier titanium titanium tungsten and chromium provide adhesion of the metal film stack to the wafer an insulating layer is formed over the metal layer fig1 a block 106 in fig2 c an insulating film 18 such as polyimide benzocyclobutene bcb etc is formed over the metal layer 16 the insulating film 18 is typically about 2 to 15 microns thick the insulating film 18 is formed using methods well known to those of skill in the art this insulating film 18 may be either photo definable or standard non photo sensitive film in the case of using a non photo sensitive insulating film a photosensitive material such as photoresist is deposited over the insulating film layer fig1 a block 108 in fig2 d a layer of photosensitive film typically 1 to 10 microns such as photoresist 20 is deposited over the insulating film 18 this layer 20 of photoresist is patterned and developed using methods well known to those of skill in the art a mask is placed over the photosensitive material such as photoresist and then exposed and etched away fig1 a block 110 the insulating film layer that is now exposed is removed using wet etch or dry etch techniques the remaining photosensitive material is also removed using methods well known to those of skill in the art fig1.