Influence of the Cu2O morphology on the metallization of Al2O3 ceramics

In this study, thin Cu2O films were first produced on a Cu foil by cathodic electro-deposition at different pH values. Then the Cu2O side of the Cu foil was closely attached to an Al2O3 ceramic substrate and heated to 1075 °C under N2 atmosphere. The effect of the pH value on the microstructure of the Cu2O film was investigated by scanning electron microscopy (SEM). The shape of the Cu2O grains changed from a 4-sided pyramid to a triangular prism to a 3-faced pyramid when increasing the pH value from 9 to 11 and 12, respectively. The X-ray diffraction (XRD) results showed that both CuAlO2 and CuAl2O4 were formed at the Cu/Al2O3 interface after reacting for 4 h, in contrast to results reported in previous papers. When the bonding time was extended to 7 h, discontinuous interfacial reaction products were found on the cross-section of the Cu/Al2O3 interface. The effect of the Cu2O morphology on the bonding strength of the Cu/Al2O3 was discussed considering the results of the flexural strength tests, and the results indicated that a uniform and dense Cu2O morphology would be beneficial for improving the bonding strength during the metallization process.