Solder joint peeling refers to the phenomenon of peeling between the solder joint and the pad. The phenomenon of solder joint peeling occurs mostly in the through-hole wave soldering process, but it also occurs in the SMT reflow soldering process.
The main reason for this kind of phenomenon is the large difference between the thermal expansion coefficient of the lead-free alloy and the substrate, which causes too much stress in the peeled part of the solder joints to separate them. The non-eutectic nature of some solder alloys is also one of the reasons for this phenomenon.
Therefore, there are two main ways to deal with this PCB problem. One is to select an appropriate solder alloy; the other is to control the cooling rate so that the solder joints solidify as soon as possible to form a strong bonding force. In addition to these methods, the magnitude of stress can also be reduced by design, that is, the copper ring area of the through hole is reduced.
