Formation of Intermetallic Compounds on the Bond Interface of Aluminum-Clad Copper and its Influence on Bond Tensile Strength

Production of aluminium-clad copper has been performed using vacuum roll bonding, hundreds nm of intermetallic compounds are formed on the bond interface. On the tensile testing, it is broken from the base metal of aluminium and high bond tensile strength is available. In this study, heat treatment has been taken to aluminium-clad copper produced by vacuum roll bonding. Microstructure observation, EPMA, EDS and XRD have been carried to the investigation of the formation of intermetallic compounds. As a result, 3 types of intermetallic compounds such as CuAl2, CuAl and Cu9Al4 were formed at the bond interface of aluminium-clad copper. And it was clarified that the apparent activation energy for growth behavior of CuAl and Cu9Al4 is lower than CuAl2. The effect of intermetallic phases on bond strength has also been investigated with the growth of intermetallic compounds. The decrease of tensile strength has been clarified. The broken position is near the interface between CuAl2 and CuAl. Furthermore, the bond strength of aluminum-clad copper is seriously affected by the thickness of CuAl2.