- Laser soldering
Laser soldering is a technique where a ~30-50 W
laser is used to melt and solder an electrical connection joint. Diode laser systems based on semiconductor junctions are used for this purpose. [cite web|title=Laser Solutions for Soldering|url=http://www.coherent.com/Downloads/circuitsassembly0204Rev2.pdf 0204 www.coherent.com]Wavelengths are typically 808nm through 980nm. The beam is delivered via an optical fiber to the workpiece, with fiber diameters 800um and smaller. Since the beam out of the end of the fiber diverges rapidly, lenses are used to create a suitable spot size on the workpiece at a suitable working distance. A wire feeder is used to supply solder. [cite web|title=Laser Soldering|url=http://www.ma-info.de/html/laser_soldering.html 070927 ma-info.de]
Both lead-tin and silver-tin material can be soldered. Process recipes will differ depending on the alloy composition. For soldering 44-pin chip carriers to a board using soldering preforms, power levels were on the order of 10 Watts and solder times approximately 1 second. Low power levels can lead to incomplete wetting and the formation of voids, both of which can weaken the joint.
References
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