Pad bending improvement on copper wire bonding on NiP/Pd/Au bond pad

摘要

Due to the high gold price, conversion from gold wire to copper wire has been a widely accepted method in semiconductor assembly for cost reduction. However, conversion from gold wire to copper wire is not a straight forward conversion. Copper wire is about 30% harder than gold wire and the commonly used bond pad metallization is Aluminium base (which is softer compare with Copper). Potential challenges include pad cratering, Al splash, lifted ball and reliability concern. Therefore, harder bond pad (plated on top of Aluminium) with Nickel as the base material was introduced. Ni which is harder than Cu, offer protection to the underlying structure, especially for probe and bond over active area products (XoAA).