Role of Oxygen in Bonding Copper to Alumina

Although the Cu—Cu₂O eutectic bonding of copper to alumina has been studied, the effect of oxygen on the bond strength is not well understood. In this study, eutectically bonded copper-alumina joints are subjected to deoxidation and reoxidation in an atmosphere with varying oxygen potential. The bond strength changes reversibly with the interface oxygen concentration. There is a critical concentration of oxygen far less than the eutectic concentration, above which bond strength shows no further increase. The role of oxygen and the practical significance of eutectic reaction are considered and discussed.