Electroless Ni-P/Pd/Au Technology for Fine-Pich PWBs

Abstract

We have already developed the surface finishing method for the terminal points of semiconductor package substrates by using electroless Ni-P/Pd/Au. This method is suitable for substrates with a high wiring density. However, the electroless Ni-P plating thickness of this method is about 3 microns or more, reduction of its thickness is necessary for higher density wiring, such as the space between terminal points less than 30 microns. It is not clarified the influence of the electroless Ni-P plating thickness to solder-boll joint reliability. So we studied the relationship between solder-boll joint reliability and the electroless Ni-P plating thickness and reflow frequency.