Corrosion Analysis of Electrical Connectors using SEM

Abstract

Electrical connectors are critical components that are often designed to perform under harsh environmental weathering conditions. Traditionally designed electrical connectors are usually aluminum with a plated/coated protective layer; these connectors are prone to corrosion and flaking, which cause issues with electrical conductivity, shell degradation, and also affect the electromagnetic interference (EMI) shielding. EMI shielding failure can result in inaccurate or distorted data [1]. Electrical connectors must operate without any conductivity failure, perform without any resistance discrepancy, and be able to mate and unmate during usage. In this study, two grades of aluminum based Ni-PTFE coated connectors were examined; they are designated Grade-A and Grade-B. The manufacturing processes for these connectors are proprietary. The connectors were tested under salt fog spray. Grade A connector was tested for 500 hours in salt fog and Grade-B connector was tested up to 750 hours in salt fog. Salt fog tests were done in a Q-fog chamber at 35 0 C and 100% humidity. The electrical connectors were cross sectioned, molded with epoxy, polished, and then examined with a Hitachi S-3400N SEM. The torque, conductivity, resistance, and corrosion visual observation as functions of connector degradation were evaluated. Grade-A connector disengagement torque and conductivity failed after 500 hours of salt fog with signs of light visual corrosion (spring finger corroded; pits, flaking, and etching). Grade-B connector failed conductivity after 750 hours of salt fog with signs of moderate visual corrosion (discoloration, flaking, etching, and pits).