Evaluation of two novel lead‐free surface finishes

Two new electrolytically plated lead‐free surface finishes are evaluated for their wettability, bond strength, and voiding performance, and are compared with electrolytic nickel gold and an OSP. The results indicate that Ni–Sn achieve the highest wettability, one of the highest lap shear strengths, and the lowest levels of voiding. It also performs better under a long reflow profile. Under most instances, the soldering performance is comparable with, or better than, the reference OSP and Ni–Au surface finishes. Ni–PdCo–Au was found to give a poor wettability, fairly low lap shear strength, and have high levels of voiding. However, it is fairly stable, and its soldering performance is not sensitive to the reflow profile length or atmosphere, aging treatment, or flux chemistry. OSP was found to be the poorest in terms of wettability, but one of the best for lap shear strength. It also performs best under long profile, is not sensitive to reflow atmosphere, is slightly sensitive to alloy type, but is very sensitive to aging and flux chemistry.