Effect of Ultrasonic Process Parameter on Resistance and Plastic Deformation of the Aluminum Ribbon Bond on Molybdenum Layer

The aim of this study is to evaluate the effect of process parameters on resistance and plastic deformation of ultrasonic aluminum ribbon bond on the molybdenum back contact layer of copper indium gallium selenide (CIGS) thin film photovoltaic (TFPV) solar panel. The aluminium ribbon was ultrasonically bonded on molybdenum with two process parameter settings with constant pressure and energy while varying the amplitude. The resistance measurement of the samples was conducted with two techniques which are the transmission line method (TLM) and micro-ohmmeter to evaluate the conductivity of the interconnection. Moreover, the plastic deformation of the aluminium bond from longitudinal and transverse cross-sections was examined by measuring the thickness of the aluminum bond. The resistance of the samples is directly proportional to the amplitude applied while the thickness of the aluminum for both longitudinal and transverse cross-sections is inversely proportional to the amplitude employed. By applying adequate pressure (3.5 bar) and energy (20 J), with the lower amplitude applied which is 7.7 µm, less plastic deformation occurs to the aluminum bond with lower resistance measured.