Thermosonic platinum wire bonding on platinum

The ever-growing need for reliable sensors and microsystems that can withstand strong temperature changes as well as impacts presents new challenges for the packaging industry. Research in this field thus focuses equally on the development of high temperature stable material systems and customized packaging technologies. Wire bonding is one of the preferred techniques, but high hardness of refractory materials negatively affects the plastic deformation process, which is the main condition for achieving sufficient adhesion between the layer and wire. In the present work, the thermosonic bonding (TS bonding) is examined and customized with a platinum wire (25 μm diameter) on platinum-coated silicon substrates (Pt thickness 300 nm). With the help of design of experiments (DoE) and the subsequent analysis of variance, suitable bonding settings have been evaluated. The outcome of the analysis of variance indicates that the platinum wire bonding is possible even at room temperature, however, the basic underlying quality criteria is not satisfied in this work. It is found that the TS bonding at a bonding temperature of 200°C is suitable for achieving an electrical contact to a thin platinum film.