Electromechanical-Metallurgical Probe Contact Wear Effects of PdCuAg Alloy in Cycling Contact With SAC 305 Solder: Semiconductor Test and Ball Grid Array Packaging

The PdCuAg ternary system in the form of a rod was studied to understand its microstructure, structure analysis, and cycling wear effect while in electrical–mechanical contact with an interconnect solder material, e.g., SAC305. The conditions under test are simulating test probe manufacturing conditions of ~33 gf, 250–350
$\mu \text{m}$
in a lineal z height displacement and ~1 A of current. This paper’s results show that solid-state diffusion from its material processing leads to microstructure solute pool segregations that in turn accelerate its wear. It is manifested in electrical degradation with high contact resistance. Ag-solute segregated microstructure produces early reliability electrical failures
$>100~\text{m}\Omega $
. Results suggest a binary data correlation of the microstructure as 25% Ag “free” last only ~25 kHz versus 1% Ag “free” last 80 kHz. A detailed discussion of how to optimize its metallurgical microstructure for improving mechanical and electrical reliability properties are discussed throughout this paper.