In power engineering, joining aluminum and copper conductors is a frequent issue. Due to the proven in-fluence of the diffusion of oxygen on the long-term behavior, this material combination is predominantly not long-term sta-ble. To achieve longevity, the oxidation in the contact interface must be limited. Thus obtaining gas-tightness to prevent the diffusion of oxygen molecules in the contact interface may be one solution to achieve a long-term stable bimetallic joint. One approach to describe this mechanism is the percolation the-ory. This stochastic procedure describes which filling of a reg-ular structure of basic geometric elements in the apparent contact area may result in gas-tight areas in the contact inter-face. Regarding research of bimetallic connections under var-ious conditions, no mechanical joining parameters of alumi-num-copper busbar connections to achieve gas-tightness were found so far.
In this paper, it is evaluated, whether joining parameters that could ensure gas-tightness can be derived using the 3D-percolation theory. Therefore, the long-term behavior of bi-metallic busbar joints depending on the mean mechanical stress in the contact interface is investigated. Furthermore, the effect of contact aid compounds on the joint resistance en-suring gas-tightness is analyzed. It is discussed, whether the percolation theory is suited to describe the gas-tightness of the contact interface of aluminum-copper-connections.