This presentation introduces a new bonding material, Ag top multilayered Al alloy base foil. It comprises an Al alloy foil as a base and Ag plated surfaces. SiC chip is bonded to Cu substrate via the foil by planer diffusion bonding. All bonding surfaces of the materials are treated with Ag. The bonding is performed in solid state with pressure and heat assists. The Cu substrate thickness is 2 mm. An assembly with sintered Ag (s-Ag) die attach are also prepared as a benchmark. The degradation of the bonding layer is investigated by thermal shock test (TST) from -40 to 150 °C up to 1000 cycles. Scanning acoustic tomography evaluates the die delamination ratio after 1000 cycles of TST. Weibull plots of the delamination ratio shows the foil have higher reliability than the s-Ag. Cross-sectional scanning electron microscopy observations after 1000 cycles reveal that the foil stick to a single fracture mode, a straight crack in the Al layer. By contrast, s-Ag coexists with straight and wavy cracks. This difference in the degradation mechanism is little discussed based on results of uniaxial tensile tests at 150 °C.
