Crack formation at the surface of solderfillets on plated through hole solderjoints, became an issue in the days that boards were soldered at so called 'Solder Cutting Solder' lines. This was a common technology in the '80-ties' of the last century. Nowadays with the use of lead-free solder alloys this crack formation shows up again. There seems to be no panacea for this phenomenon, since changing of the process parameters will hardly give any improvement.
This article will describe the main physical mechanism that can be held responsible for these effects.
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