Mission "In-depth Look"

Challenges

One of the things that the ILT and TRUMPF team want to take a close look at under the high-brilliance X-ray light is the welding of metal-ceramic substrates (MCS). These MCS's connect electronic components in a high-voltage environment, such as the performance electronics of an electric car. A wafer-thin layer of copper is applied to an insulating ceramic plate. The car manufacturers want to use the green laser to weld another copper component onto the MCS for contacting. A copper-to-copper connection is involved. The question is now: How can everything be optimised in the welding process? The copper plates should be as thin as possible, the process should be extremely fast, the seam should hold 100% and the ceramic must not be affected by the laser. In short: How does one find the perfect laser setting for the most productive process?

Solutions

Together, Fraunhofer ILT and TRUMPF decide on an unusually complex investigation of the problem: They want to see pin-sharp X-ray videos of the ongoing laser process and - using all analysis tools - they want to observe with their own eyes what effects the smallest changes in laser parameters have on the welding depth, pore formation and spatter formation. In Germany, this is only possible at the DESY electron synchrotron, where basic scientific research is normally carried out. As one of the first industrial projects, the ILT and TRUMPF secure a spot in one of the laboratories at the facility where such X-ray videos are possible.

Implementation

Three days of laboratory work at DESY are booked - the preparation for this takes two whole years: The team develops a test methodology and defines the exact scientific queries. For them it is very important to forge a precise plan in advance, to explore how the findings can later be implemented in specific industrial applications. In December 2022 the time has come: Both teams pack up laser technology, optics and other technology and meet at DESY. In the laboratory there at the Beamline P07, the teams set up the TruDisk 2021 disk laser for the green laser light and the test configuration: The X-ray light falls on the sample from the side and records the image sequences inside, a laser welds from above, and a robot changes the samples to speed up the process. The idea is to make optimal use of the three days. The prepared tests are run in shifts, 24 hours a day. Cola and crisps help the scientists keep their focus. The MCS alone accounts for more than a hundred experimental runs.

Forecast

Terawatts of data are generated on welding precision, welding speeds and so on. At DESY, the scientists from ILT and TRUMPF are already starting to analyse the first impressions. But the main work of the evaluation does not start until the weeks after the DESY experiments. In Aachen at the ILT and in Ditzingen at TRUMPF, analysts are poring over the tables, videos and sensor data. Thanks to the precise planning, it soon becomes clear how laser welding will look once it has been optimised in every respect, for example by MCS in power electronics for e-mobility. The automobile manufacturers are waiting.