In a cold solder joint, a distinct, complete and materially integrated bond connection between the parts to be joined and the solder is not present. In the lead-free soldering process, cold joints are very difficult to recognize, and they can be the trigger for reliability problems of an electronic assembly. The causes for cold joints are manifold. Amongst the most common causes for this defect are disturbances such as vibrations during the cool down period of the solder, or a too high process temperature which has caused the flux to break down prematurely. Another possible cause could be a process temperature at the solder joint that is too low, so that complete wetting could not take place.