Nanostructured alumina coatings for room temperature processability of an bonding wires

Wire bonding is the most common technology to connect bare dies on hybrids. For such applications, e.g. automotive applications or sensor modules, highly reliable Au/Au interconnections are preferred. But the standard ball/wedge bond process for Au-wires requires temperatures over 120 degrees C, which is a serious disadvantage when connecting temperature sensitive devices. One of the most promising solution to overcome this problem is alumina coated Au bonding wires. In the present work we have studied the characterisation and optimisation of coated gold wires for ultrasonic wedge/wedge bonding, including the optimisation of wire bond process parameters, reliability testing and material characterisation of the metallurgical state of the wire bonds.