Innovation project: Intelligent copper bonding
In mechanical engineering and automotive engineering, current and voltage are controlled and switched by power semiconductor modules. The electrical connections between individual electrodes in these modules are called bonds. These consist of aluminum wires that are applied to the electrodes by special bonding machines using an ultrasonic friction welding process. Due to growing markets in renewable energies and electric vehicle use, the performance, reliability and efficiency of power modules must be improved. This is not possible with the bonds used so far, due to the limited physical properties of aluminum – including its conductivity, strength and durability. This means that aluminum bonds must be replaced with copper bonds, which have significantly better properties. However, the copper bonding process is more sensitive to external influences on production and material fluctuations, which can compromise the quality of the bonds and lead to higher reject rates. As a result, copper bonds currently cannot be produced with the required degree of reliability.
The aim of the research project is to develop self-optimizing processes that allow the production of reliable copper bonds under variable manufacturing conditions. It is hoped that bonders will become capable of automatically adapting to changing conditions.
To that end, external variables – such as temperature and material – are analyzed together with process parameters – such as power and duration – and their impact on the quality of the copper bonds. This is used to define an ideal bonding process. The next step is to develop condition monitoring and self-optimizing control systems for the bonder, allowing external influences to be analyzed and process parameters to be autonomously adapted. This involves drawing on the results of cross-sectional projects in self-optimization and systems engineering. Condition monitoring and self-optimization are validated by means of a prototype, optimized as necessary and then integrated into the bonder.
The results allow copper bonds to be produced at a reliably high quality, making power semiconductor modules more powerful, efficient, compact and durable. The maximum module current is predicted to increase by approximately 50%, for example. Semiconductor manufacturers expect that copper will be used for most bonds in the near future. The market volume is estimated at around EUR 10 billion per year. The results can be transferred to other production processes, such as those in mechanical engineering, automotive and medical technology.
01 January 2013 - 31 December 2015