Pure palladium in ENEPIG surface finishes — Physical properties of the Pd deposition and their influence on soldering and wire bonding

As a surface finish, electroless nickel / electroless palladium / immersion gold (ENEPIG) has received increased attention for both packaging/IC-substrate and PWB applications. With a lower gold thickness compared to conventional (ENIG) the ENEPIG finish offers the potential for higher reliability, better performance and reduced cost. This paper shows the benefits of using a pure palladium layer in ENEPIG and ENEP (Electroless Nickel / Electroless Palladium) surface finishes in terms of physical properties and in terms of gold wire bonding and solder joint integrity.