The project "Next Generation Solar Cell and Module Laser Processing System - Solasys" was successfully completed in mid-2011. For more information, please contact directly the coordinator.
Setup and evaluation of an ultra-short pulsed laser with MHz repetition rates and high average power for ablation and isolation
Setup and evaluation of a high brilliance drilling laser
Setup and evaluation of high power diode lasers for cell interconnection
Main Project Achievements Trumpf designed, set up and delivered two process-adapted laser sources. The ultra-short pulse laser makes use of a new cavity design without additional amplifiers and achieved 45 Watts output power at 1 picosecond pulse duration and 3.5 MHz repetition rate. This laser was designed for isolation and ablation processes. The laser parameters allow high volume removal rates with athermal characteristics of ultra-short pulses. However, due to the high pulse overlap at common scanning speeds (<20 m/s) thermal effects cannot be avoided. It was found that for both isolation and ablation this effect can be exploited in a beneficial way.
The laser designed for drilling achieves 700 Watts of average power with repetition rates between 14 and 100 kHz and pulse durations of 700 ns. The pulse energy, a critical parameter for laser drilling, is limited by the fiber coupling with a 50 µm core fiber to 7.5 mJ. While the volume removal rate of this laser source can be as high as 17 mm³/s in Silicon (about three times higher than for commercially available lasers), the achieved focal diameter of 100 µm (using a 163 mm focusing optics) is not sufficiently small for high rate drilling.
Laserline designed, set up and delivered two high-power diode lasers for cell interconnection. The high power solution for simultaneous soldering is specified with 3kW average power and a beam quality of 100mm*mrad. In combination with a line focus optics creating a 170mm x 2mm focus, this laser allows simultaneous soldering on one busbar within 0.5 seconds. The second laser, which is used for the scanner-based quasi-simultaneous soldering approach, is specified with 500 Watt average power and a beam quality of 20 mm*mrad. The high beam quality allows a focus size of 1 mm and scanner-based soldering.