Corrosion and adhesion of multilayer pad structures for packaging applications

Corrosion resistance and adhesive strength for different multilayer pad structures used in electronic packaging applications are examined. In particular, multilayer pad structures with Cr/Cu interfaces are compared to similar Cr/Ni/Cu structures containing a layer of Ni between the Cr and Cu layers. Structures with Cr/Cu interfaces are found to be susceptible to delamination following exposure to highly corrosive conditions. Corrosion apparently results in the formation of crack initiators at the edge of the multilayer pad structure. Ni interlayers between the Cr and Cu layers very effectively reduce this susceptibility to delamination because mutual solubility of Ni with both Cr and Cu causes better adhesive strength by interlocking of the layers