Executing Organisation: German Research Foundation (DFG), Transregio 39
The laser-assisted droplet-jet brazing process is to be qualified as a high-temperature-stable joining method for previously incompatible material pairings in electronic assembly and connection technology in industrial environments. It is to be extended with regard to the usable solder materials and geometries in order to produce electronic connections which are not possible with the standard methods. A great advantage compared to conventional joining techniques is that the method is contactless and enables force-free joining while using filler material.
In the first step, different solder preforms with different melting temperatures and strongly varying absorption behavior are investigated with regard to their melting behavior in order to determine the necessary energy deposition into the solder preform and the joining zone. Based on the determined findings from experimental investigations as well as simulative considerations of the overall process, the process and material limits for an economic process design should be generally derived. As a result, a prototypical system will be developed together with the project partner in order to establish the process that has not been used in the industrial environment up to now.
Based on the determination of process windows and the evaluation of failure mechanisms in the process, basic statements, such as the flight behavior of the solder preforms (see pictures below) and the wetting behavior of joining partners and capillaries, were derived in order to be able to abstract a generally valid simulative process model. This makes it possible to estimate the scalability of the process, for example for larger solder preforms and the use of different capillary designs with regard to the industrial use of the process. Different process influences, such as the energy input into the solder preform or the inert gas overpressure were iteratively evaluated in order to achieve an optimum in process control in terms of precision and repeatability.