Thermocompression bonding of gold is a promising technique for achieving low temperature, wafer-level bonding without the application of an electric field or complicated pre-bond cleaning procedure. The presence of a ductile layer influences the fracture behavior of the bonds. The effect of plasticity was explored by varying the gold bonding thickness between 0.23 to 1.4 μm. The bond toughness of wafers bonded at 300°C under 0.5 MPa of pressure were characterized using a 4-point bend delamination technique. Cohesive failure was found to be the dominant fracture mode in the thicker films. Bonds made with thin gold films failed adhesively and at lower strain energy release rates.
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