Improvement of Wire Bond Strength to Electroless Au/Pd/Ni-P Plating Pads on Printed Wiring Boards by Knocking in Plating Bath

Abstract

Au wire bond strength on Cu interconnects printed wiring boards was investigated for electroless Au/Pd/Ni-P pads plating prepared with knocking substrates in plating baths. A scanning electron microscope revealed that the surface of NiP plating formed with knocking was smoother than that of NiP plating formed without knocking. Furthermore, X-ray photoelectron spectroscopy indicated that no a Ni peak was recognized on Au/Pd/Ni-P plating formed with knocking, while a Ni peak was observed on ones formed without knocking. The wire bond strength to Au/Pd/Ni-P plating pads formed with knocking was larger than that to ones formed without knocking. These findings are due to removing hydrogen from a NiP surface by knocking substrates during formation of NiP plating.