PCB Soldering Issues

PCB pads are easily peel off when the circuit board is being soldered or under repaired. In this article, some reasons for the falling off pads are analyzed, hope it is useful for your next project.

Reasons for easily falling off pads

1.Board quality issue. Due to the poor adhesion of the resin adhesive between the copper foil of the copper clad laminate and the epoxy resin, even the copper foil with a large area copper is slightly heated or mechanically stressed, it is very easy to separate with the epoxy resin which leads to the pad off, copper foil off and other issues.

2.Circuit boards' storage conditions.Affected by the weather or stored in the humid place for a long time, circuit boards absorb too much moisture. To achieve the desired soldering effect, SMD soldering needs to extend soldering time and temperature to compensate for the heat away due to moisture evaporation. Such soldering conditions easily separate copper foil and epoxy resin.

3.Problems caused by soldering irons.Generally, the adhesion capability of PCB boards can endure ordinary soldering process, which means no pad off phenomenon will happen However, electronic products generally needs repaired when running for a long time, repair by soldering iron is always the top choice. While the local high temperature of electric soldering iron can reach 300-400 degrees, and this made the temperature of pads up too high immediately, then resin will be off due to high temperature soldering, and pads will definitely be peel off.

Since pads are easily fall off, PCB manufacturers should take following steps to improve solder resistance to meet customers’ needs.

1.CCL suppliers should have good reputation for high-quality substrate they produced. Generally, copper clad fiberglass material selection and lamination process should ensure that the circuit board made of solder resistance will be in line with customer requirements.

2.Put desiccant and vacuum packaging the PCB board before shipping. Keep the circuit board always dry can reduce virtual welding and improve solderability. 

3.As to the effect about thermal shock caused by the soldering iron on pad, try to increase the thickness of the pad by plating copper foil. In this way, when the soldering iron heats the pad, the thermal conductivity of the copper pad is greatly enhanced, effectively reducing the local high temperature of the pad, and at the same time, the thermal conduction makes the pad detachable more easily and the soldering resistance of the pad is achieved.