Effects of Joining Conditions on Joint Strength in Molten Aluminum with Aluminum Nitride Substrate

Abstract

  The effects of joining conditions on joint strength in molten pure Al with AIN substrates were examined. In the bending test of laminated specimens, high maximum shearing stress was obtained under high pressure and/or high temperature. The maximum shearing stress also showed a similar tendency to thermal cycling performance. Both the maximum shearing stress and thermal cycling performance were considered to be reflected in the joint strength. These findings indicate that high joint strength was obtained under high pressure and/or high temperature. On the other hand, the maximum shearing stress showed greater variation under a long holding time, suggesting that the progress of oxidation decreases the reliability of joint strength. From the appearance and optical micrograph of the bending specimens, finely-fractured Al layers were found adhered on both delaminated surfaces under the conditions where higher maximum shearing stress was measured. This result suggests that the joint strength has the potential to be as high as the shearing strength of pure Al. Weibull plots of the maximum shearing stress implied that high-reliability joining can be achieved by both good wettability and prevention of oxidation.