Thermal joining processes for SMA

The reliable integration of SMA components is an essential task in the manufacture of SMA applications. Therefore, in addition to mechanical technologies for joining SMA, Fraunhofer IWU is also investigating thermal joining processes to make systems more reliable, flexible, and economical. The objective here is to transfer general advances in the field of thermal joining technologies and processes, in combination with existing material know-how, to the joining of SMA. Furthermore, the technology is to be investigated and adapted to SMA-specific requirements and characteristics.

One example of this is the precise positioning of thin SMA wires. In principle, the optimal joining technology always depends on the application. In the field of SMA sensor technology, very fine SMA structures such as 5µm thin films or SMA wires with diameters of 20 µm must be joined. In particular, joining processes such as soldering, spot welding, laser beam welding, and ultrasonic welding are being researched here.  If the wire diameters increase, e.g., in the field of actuators with diameters of up to 200 µm, laser beam welding is used in particular.

Project partner: SITEC Industrietechnologie GmbH, EC Europ Coating GmbH