The perfect laser for microprocessing

In the field of microprocessing, laser light is primarily used for the precise removal of material. Pulsed Q-switched diode-pumped lasers are used for this purpose. TRUMPF has designed and developed a new laser series especially for microcutting, etching, drilling and structuring. According to the specifications, the fluctuation in output power is below one percent and the maximum angle deviation of the exit beam is under 10 mrad.

High pulse energies – high repetition rates

The average output of up to 30 W of the TRUMPF TL Q lasers with a so-called Q-switch, can be converted physically either into high pulse energies or high repetition rates. The specific application determines which pulse properties are best. TRUMPF therefore offers lasers with two different laser-active media. While the TL 20-1 LQ with YLF-rod offers particularly high pulse energies of up to 4 mJ at 4 kHz, the TL 35-1 VQ with Yttrium-Vanadat (YVO4)-rod achieves repetition rates of up to 200 kHz. Nevertheless, with 30 kHz, up to 1 mJ of pulse energy is available. The pulse widths are dependent on the pulse energy and are between 15 and 80 ns.

The output is regulated not by controlling the excitation, but rather from pulse-to-pulse outside the resonator. The overall opto-mechanical resonator system is therefore in a state of equilibrium during operation. In addition to power stability, some micro applications, such as drilling, require an additional exact round beam profile. The advantage of a symmetrical beam is its consistent power distribution without fluctuations, before, during and after the focal point. TRUMPF microprocessing lasers are used in any application for which the benefits of touch-free, flexible and precise material ablation are evident.

Laser ablation of semi-conductors, ceramics or steel

One example is the processing of crystalline silicone solar cells. In principle, they consist of one pn-transition in which the emitter is only a few nanometers thick. The production method causes a short circuit on the edges of the solar cells which reduces the available electric current. Up until now, this short-circuit has primarily been removed by means of machine grinding or by etching. In conjunction with scanner technology, the TRUMPF TL Q microprocessing lasers offer a new approach. The electric charge carriers are removed by vaporizing the material. About 50 to 70 mm wide grooves with depths of 5 to 10 mm is generated by the pulsed laser light along the edges of the solar cell. The individual pulses are very rapidly and precisely positioned by means of scanner optics. Thanks to the high repetition rate, these systems generate the macroscopic overall lengths of the grooves in a short time.

The short pulses are also perfectly suited for drilling and structuring steel and hard metals. Thus, in 1 mm thick steel, it is possible to drill holes with diameters of between 50 and 200 mm at a tolerance of 1 mm. Also, microstructures are generated to improve the tribologic properties of sliding surfaces. The tribologic conditions in the contact zone define the workpiece quality and tool service lifetime in forming technology as well as precision cutting and punching tools. In combustion engines they affect the consumption of oil and fuel. This innovation was a development of common interest of pilot customers in the network.

Contact:
Dr.-Ing. Andreas Ehrhardt
(Director)

Photonics BW e.V.
Competence Network for Optical Technologies 
Carl-Zeiss-Str. 1
D-73447 Oberkochen

Phone: +49 (0)7364 202913
Fax: +49 (0)7364 204903
eMail: ehrhardt@photonicsbw.de
Internet: www.photonicsbw.de

Further Information:
www.trumpf-laser.com