Long-Term Behavior of Current-Carrying Connections

Current-carrying connections age depending on operating and environmental conditions. Aging increases the contact and connection resistance, thereby increasing the power loss and the temperature of the connection. Currently, five mechanisms are known that determine aging depending on the type of connection and the joining elements used (Fig. 5.1). In current-carrying connections with contact partners made of the same conductor materials, the force reduction, chemical reactions and at sufficiently high current density, electromigration dominate the long-term behavior. In bimetallic connections, interdiffusion must also be taken into account. If relative movements, caused by thermal expansions or during switching and plugging processes, are possible between the contact partners, friction wear must be considered.