The finite element modelling of laser soldering for electronic assemblies

The laser provides a controllable means of supplying localized energy for solder joint formation and is a valuable tool in electronics manufacture. The modelling of heating behaviour in typical structures requires consideration of many different phenomena and the resulting models can become complex. The work described here shows that, given appropriate modelling assumptions. finite element models are able to give accurate predictions of heating in high-pin count devices as well as a valuable insight into the important factors affecting the success of laser soldering operations. In particular, it is shown here that conduction through the body of the component being soldered does not significantly affect heating of the solder but that variations in copper track thickness can result in a doubling of the required soldering time. In addition, it is shown that conduction through the printed circuit board is important when using a scanned laser beam to solder multiple joints. Copyright (C) 2002 John Wiley Sons, Ltd.