Fraunhofer Institute for Reliability and Microintegration IZMDevelopment of wire bonding processes for future application fields
The development and testing of new wire materials and surfaces, particularly for power electronics, has been a key focus. An innovative Al wire with selected alloy elements (currently known as AlX wire) features much higher resistance against softening at the high ambient temperatures that electronic devices are often exposed to during the assembly process. This should yield longer lifetime at alternating bending stress. Despite the fact that only a prototype of the wire has been investigated to date, the level of bondability and the bond quality achieved are very promising.
Another key area is Al-cladded Cu wire. Active power cycling experiments with Al-Cu wire on standard semiconductors are currently being prepared. The results will be used to assess whether the bonding wire improves lifetime.
Advances in active power cycling equipment have proven very useful in our investigations. It is now possible to conduct active power cycling experiments under varying environmental conditions. Our customized cooling systems and test equipment allows for cyclic variation of temperature between -40 and 150 ° C. These varying environmental conditions can be adjusted as required for the loads being tested. We plan to use this system for a series of investigations into the influence of overlapping and interacting failure mechanisms in power electronics.
Another breakthrough was our demonstration of the viability of wire bonded battery cells. By modifying the wire bonding equipment to optimize the battery surface and geometry, we demonstrated the feasibility of automated bonding of several hundred battery cells.