A study on the reliability and thermo-mechanical properties of gold ribbon wire bonding

The major goal of this research is to study the thermomechanical properties of the Au ribbon wire bonding and its reliability in a TO-receiver. The metallurgical behaviors have effects on the wire looping and thus the mechanical strength of the ribbon wire. It was studied by performing the vertical pull test and bond shear test; its pull force, interfacial shear force and failure mode was recorded. These mechanical tests were also employed to analyze samples that have undergone aging test (150°C). Wire pull force and shear force versus aging test time were recorded and the failure mode obtained during shear test was studied. Correlation between the bond area and wire bond strength was also reported. Metallurgical sectioning was also performed on the aged samples at each aging test intervals. A mathematical model was used to predict the unit change in resistance of gold ribbon wire in various surrounding temperatures and strain states. The investigations involved environmental temperatures, i.e., 25, 85, 100 and 125°C were employed. In the elastic range and the initiation of the plastic range, the variations in the electrical resistance of ribbon wire are dominated by the thermal effect. However, the tensile strain replaces the thermal effect within the later half of the plastic range.