Mechanical performances of AlN/Al metallized ceramic substrates fabricated by transient liquid phase bonding and pre-oxidation treatment

Abstract

For the miniaturization of high-power electronic components, AlN/Al is a promising metallized ceramic substrate due to its superior mechanical and thermal performances. Numerous bonding processes have been proposed for fabricating the metallized ceramic substrate. Unfortunately, the influences of various bonding techniques on the mechanical performance of AlN/Al metallized ceramic substrate remain undetermined to date. The objective of this study was thus to investigate the effects of the transient liquid phase (TLP) technique and pre-oxidation treatment on the bonding, microstructure, and mechanical strength of the AlN/Al metallized ceramic substrate.The results indicated that the three-layered AlN/Al/AlN specimen could be effectively bonded by the TLP process and pre-oxidation treatment. However, the bending strengths of the specimens fabricated by the two techniques were obviously divergent. The bending strength of raw AlN substrate was 333 MPa. In contrast, the bending strengths of the three-layered specimens with AlN substrates pre-oxidized at 1050 °C, 1150 °C, and 1250 °C were 292 MPa, 250 MPa, and 224 MPa, respectively. Raising the pre-oxidation temperature of the AlN substrate from 1050 °C to 1250 °C obviously increased the thickness of the Al2O3 layer and deteriorated the bending strength, for the fracture propagated along the Al2O3 layer and the Al2O3/AlN interface. For the TLP bonding, the Cu film deposited on the AlN substrate contributed to the generation of Al–Cu transient liquid and to bonding. The bending strength of the three-layered specimens fabricated by TLP at 650 °C was 417 MPa, which was 25% and 43% better than those of the raw AlN substrate and the three-layered specimens prepared by the pre-oxidation treatment, respectively.