Influence of Oxide Film on the Bondability of Aluminum in Ultrasonic Bonding and Materials Evaluation of Bonds

Abstract

We performed ultrasonic bonding on sheets of 1050 and 5052 with different oxide thickness of 4, 15 and 30 μm. The oxide films macroscopically bent and distributed like whirl-shaped near bond interfaces. Microscopically, we observed two kinds of features of the oxide films, dot-shaped and line-shaped. We evaluated the bonding situation by an immersion method of ultrasonic testing (C-scope mode). The ratio of good bond area was ultrasonically obtained and depended on the thickness of the oxide films and input energy in bonding. The maximum tensile shear load decreased with the increase in the thickness of the oxide films. By using the results of both a tensile shear test and the good bond area obtained ultrasonically we could estimate the tensile shear strength of bonds.