Effects and interactions of design parameters for gold-plated electric contacts

Abstract

Many of the reliability issues affecting separable connectors can be traced to the contact interface. In order to design robust, reliable connectors and sockets, the effects and interactions of design parameters on the reliability of the contact interface must be examined, especially in the limited design space presented by such applications as high density LGA sockets. A full test matrix was applied with varying levels of normal force, gold-plating thickness, contact geometry, mixed flowing gas exposure, and wipe. A statistical analysis of the results and multiple linear regression models are also presented. When making contact to gold-plated surfaces, the presence of corroded pore sites dramatically affected the contact resistance. Contact resistance readings were taken both on and off corroded pore sites. When contact was made off corroded pore sites, the resistance values were not significantly higher than unexposed gold values and the combination of normal force and contact geometry were the most significant variables. Small amounts of wipe were shown to decrease the contact resistance and backwipe was shown to have little effect on the contact resistance. Contact on corroded pore sites was found to yield extremely high contact resistance readings, many of which were open-circuit. In general, satisfactory results were achieved if contact was not attempted on corroded pore sites.