Benefits of pure palladium for ENEP and ENEPIG surface finishes

This paper compares the properties of pure palladium versus palladium-phosphorus deposits in surface finishes ENEP (electroless nickel/electroless palladium process) and ENEPIG (electroless nickel/electroless palladium/immersion gold). ENEPIG pand ENEP has recieved increase attention for both packaging/integrated circuit-substrate and PWD applications. The investigation is in terms of hardness between the two types of palladium layers, internal stress, solder spread, surface topography, gold wire bonding process window and copper wire bonding capability. Results show that using electroless pure Pd deposition can enhance the performance of ENEPIG and ENEP surface finishes. In addition to offering the reduction to cost by allowing the reduction in gold thickness, the ENEP surface enables next generation interconnection techniques.