Performance testing and evaluation of a Ag-W nano-crystalline silver alloy as a gold replacement in electrical connectors

Abstract

Silver's unique performance combination of excellent electrical and thermal conductivity has always been considered very desirable to be used in high signal density, electrical interconnect systems. However, silver's poor mechanical performance, due to its lack of hardness and susceptibility to surface tarnishing, has limited silver's applications to connector systems that require low durability and high contact normal forces, such as power connectors. This paper will present the material properties and results from reliability testing for a new electroplated nano-crystalline, cyanide free, silver alloy on a nickel barrier layer, that can be considered as an alternative finish for hard gold traditionally found in the separable interfaces of high signal density, electrical interconnect systems. The study shows the new silver alloy technology stack presented in this paper provides improvements to its mechanical, electrical, and thermal properties such that, in conjunction with the mechanical properties of the nickel corrosion barrier, should enable the technology stack to meet the performance requirements in accordance with the Telcordia GR-1217-CORE specification and EIA-364 test procedures.