In diode laser soldering, a focused laser beam provides fast and controlled heating of the solder alloy to reflow the solder and to form the joint. Laser radiation in the range between 808nm and 980nm is well absorbed by most solder alloys, making fiber coupled diode laser systems ideal for this application. Lasers with output power in the range of 30W – 80W are sufficient for standard solder applications. The heat cycle can be precisely adjusted to the joint size to avoid overheating and fast quenching during the cooling phase. Spot sizes for solder joints can reach from the 0.2mm into the millimeter range and typical cycle times range between 0.6 and 1.0 seconds per joint. Laser soldering can be performed with lead based and lead-free solders.
Laser soldering is a solution for applications that require selective solder joints such as connecting a circuit board to external terminals or for repair work. In both cases, conventional reflow or wave soldering cannot be applied. The compact size of Visotek’s diode lasers and the fiber beam delivery provide great manufacturing flexibility. System solutions can be easily customized to meet the requirements of complex parts — thus delivering consistently high-quality joints that are more cost-effective, than traditional hand and hot air soldering. High speed scanning optics can be used for fast beam repositioning between solder joints. Beam splitting optics that divide the laser beam into several individual laser spots is an approach to simultaneously solder multiple joints and therefore increase throughput.