Effect of coating materials on the electrical performance of copper joints

Films on the surface of contacts creat an excess of the electric resistance which can cause failures in contact applications. Humidity in the atmospheric environment also influences the surface of contacts. The coating of copper busbars with different metals is one of the most common commercial practices used to improve the stability of the connections and to prevent ambient corrosion. In this work, silver and nickel coating materials used for copper-to copper connections were evaluated on the basis of their effect on the contact resistance, the transient and steady state behavior of the joints. The effect of coating materials on the performance of electric contacts and the life time of joints is presented. Also, the effect of humidity and the oxidation film resistance on the performance of electric copper joints is analysed. Moreover, the cost of power dissipated through the coated and uncoated joints is calculated. Also, the effect of the current cycling on the contact temperature, voltage drop, and contact resistance is presented. The results show that silver and nickel plating of copper ensures the best performance under different operating conditions. The coating connections show excellent stability and low initial contact resistance. Also, the cost of power dissipated through the coated joints is less than for uncoated joints so energy can be saved and the life time of coated joints is increased.