Semiconductor lasers for microsoldering

The minimal rise in substrate temperature reduces mechanical stress, the rapid melting and cooling of the solder prevents the formation of intermetallic compounds. Recent advances in semiconductor physics have brought about the availability of semiconductor laser diodes capable of delivering CW powers of 1 watt from single diodes and 5-10 watts CW from `multiple emitter´ devices. These power sources emit at a wavelength of 800-900 nm. The semiconductor laser diodes exhibit efficiencies of around 30% and can be powered from a 2 volt source! From work on laser soldering by Lish (1985) and Greenstein (1989) it has been shown that the efficiency of energy absorption increases as the wavelength decreases. Thus in this respect the semiconductor laser is more efficient for soldering than the Nd:YAG laser. Add to this the advantages of compactness, and the future for these devices in automated soldering systems becomes attractive. Fibre optics can be used to transmit their energy