Evaluation of different contact aid compounds for aluminum-to-copper connections

Many types of contact aid compounds, such as lubricants and inhibitors, are being used to ensure reliable connections between current carrying contacting members of power connectors. Most are commercially available, but little information has been published on their performance under accepted service conditions. Furthermore, no comparative study has even been made of the efficiency of these contact aids in maintaining uninterrupted operation of aluminum-to-copper connections under service conditions. The objective was to study the effect of such compounds on the stability of electrical connections under different operating conditions. For this purpose, a number of contact aid compounds was selected and subjected to parametric and stability tests. They were then evaluated and ranked on the basis of their spreading tendency, effect on the performance of a joint under current cycling conditions, and ability to protect the contact against fretting. The force torque and the contact resistance force relationship were also determined for different types of contact aid