Vitesco Technologies is using green laser systems from its long-standing production engineering partner TRUMPF for copper welded joints for production of battery management electronics for the BMW Group. The energy consumption for the welding assembly can be reduced by 4% just by substituting the beam source. Vitesco Technologies is an early adopter in the serial use of this solution.
Copper (and gold) have high reflectance and are difficult to weld using conventional infrared laser welding technology (wavelength of around 1030 nm). Laser-specialist TRUMPF developed a green laser system for industrial production which operates in the visible light spectrum with a wavelength of 515 nm. The shorter wavelength makes laser absorbance in copper much higher than with a conventional laser, and without reflection.
Compared with infrared laser systems—the standard in copper welding to date—the use of green lasers can reduce energy consumption by up to 20%, depending on the application, and thus the CO2 footprint per laser welded joint. At the same time, production becomes more sustainable by the fact that green laser systems cause virtually no copper spatter during welding, which otherwise means more effort during production.
Our sustainable manufacturing with smaller CO2 footprint and very stable processes is a competitive advantage. Because for vehicle manufacturers, sustainability with the highest quality is strategically relevant. That is why the use of green laser systems is important for us.—Thomas Stierle, member of the Executive Board at Vitesco Technologies
Welding copper is a complex process. At the same time, the requirements for copper welded joints and their number in electrification products are increasing. Up to now, copper has been welded using infrared laser systems (IR lasers). This process is difficult to control, however, because the amount of energy absorbed by the copper during the welding process changes abruptly after a certain point.
Initially, the copper reflects almost all of the laser radiation before the weld suddenly heats up. Complex measures are required to protect electronic systems from the copper spatter that can be generated in the process. Because of the initial high reflection and low energy absorption, IR lasers require a lot of power, which makes them less sustainable compared to green lasers.
Green lasers are far more efficient for welding copper than IR lasers. The new systems require less electric power and still deliver an unprecedented stable, repeatable process with a precisely controlled depth of penetration into the copper.—Rainer Pühl, head of operations in the Electrification Technology business unit
Due to these features, green laser systems are currently being made into a company-wide standard technology option for certain applications.
Welding copper is a task that is as frequent as it is challenging for us. Together with TRUMPF, we developed the new green laser application in three years.—Rodrigo Peres, head of the battery product line at Vitesco Technologies
Green laser systems with a power of 2 kW are currently being used to mass-produce highly integrated and highly complex battery management electronics for the BMW group.
The green laser has great potential for many electrification products. In addition to electronics, this also applies to electric motors. Among other things, we can use the welding process on a highly efficient stator with 138 welding points per motor.—Rainer Pühl