Soldering terminology

Directly after soldering of a Sn-Pb solder alloy, the dendrites are supersaturated with tin. If the solder is stored at room temperature for a few days, the excess tin is precipitated and a softening occurs together with the reduction of internal mechanical stress . This is why we speak about age softening. Figure 1 is a micrograph of the recently solidified solder while Figure 2 shows the precipitation of tin. The addition of Sb counteracts age softening.