There are many different reasons for the formation of voids and a major factor are details. One reason could be that the solder pin including the solder pin casings seal the hole where the pin is placed tightly from above and thus prevent the air from escaping upwards from the solder joint. In this case it is possible that the hole diameter is too narrow for the pin and that the pin has to be changed during a product review. Another reason may be a steam cushion created by the flux. This cushion creates an increased vapor pressure which vents through the solder joint. This creates cavities and crater-shaped defects in the surrounding solder-meniscus. Vapor pressure can also be generated in the circuit board if the moisture in the circuit board forms a vapor cushion during the soldering process and expands in the form of a void at the solder joint. For this reason, printed circuit boards should be dried for about 1 to 2 hours at 80 to 100°C after being manufactured.
Do you have questions regarding this matter?
Your contact person: Matthias Fehrenbach
Company: Eutect GmbH