Failure analysis for poor vertical fill of ENIG holes

Wave soldering is one of the most widely used soldering methods in the electronics industry. However there are many influences that caused to soldering failure. This article presents a typical case about poor vertical fill failure analysis during wave soldering. Base on a series analysis, such as surface element detected, vertical cross section, thickness of inter-metallic compound (IMC) measurement, energy dispersive spectroscopy (EDS) analysis etc, the poor vertical fill failure is primarily attribute to that the soldering heat is not enough. The contaminated surface and the Ni corroded intensify the failure.