Contact material may be fed into the welding line as a pre-formed tape incorporating two or more layers of different metals.
With bi-metal tape, the contact material forms the facing layer and the backing layer - a base metal that is easy to weld - is bonded to the carrier. Tri-metal tapes consist of a highly conductive metal, such as copper, placed between the contact layer and the backing layer.
The riveting process is typically used when very thin carrier materials are involved, because welding is not a practical method of applying a contact to a thin carrier strip. Riveting is also used when applying metals that are resistant to welding, such as AgSnO, AgZnO, to avoid potential damage in the HAZ (heat affected zone).