The High Temperature Deformation Properties of Gold and Thermocompression Bonding

The flow stress of a high purity gold has been determined so that the contribution of plastic flow to the gold<jold thermocompression bonding process can be evaluated. These compression tests at 25°C, 158°C, 311°C, and 458°C indicate that for deformations over 15% the flow stress and the work hardening coefficient decrease rapidly with increasing temperature. Correlation of the compression test results and beam lead bonding experience indicates that high purity golds having a hardness of about 30 DPH would be expected to reach a steady state uniaxial flow stress of 70-90 MPa (10,000-13,000 psi) when deformed during bonding at 300°C.