The investigation of the performance of bondability and solderability on various substrate surface finishes

In this paper, we studied the characterization for various surface finished, such as electroless nickel electroless palladium immersion gold (ENEPIG), electrolytic Ni/Au, and Organic Solderability Preservation (OSP). It was found that the bondibility result of ENEPIG was comparable with electrolytic Ni/Au, though ENEPIG surface showed larger grain size and higher surface roughness than that of electrolytic Ni/Au. About ball reliability, Sn3.0Ag0.5Cu (SAC305) jointed on ENEPIG surface, it has the highest soldering strength no metter in cold ball pull or shear tests. The thermal aging test showed that ENEPIG and OSP had similar performance, while electrolytic Ni/Au was the worst one at high speed shear test. About the board level drop test, all of test vehicle were pass JEDEC Standard (30 times with 80% fail), and ENEPIG and OSP are better than electrolytic Ni/Au. For normal and high-speed SMD shear tests, ENEPIG and electrolytic Ni/Au had similar shear strength before thermal aging; however, the shear strength of electrolytic Ni/Au decreased significantly with increasing aging time, but ENEPIG still remained.