Analysis of the reason why the pad is easy to fall off when the circuit board is soldered

During the soldering process of the circuit board, the pad peeling often occurs. Especially when the circuit board is reworked, when the soldering iron is used, the phenomenon of the pad falling off is very easy. In this paper, the circuit board factory analysis the reasons for the peeling of the pad and takes corresponding countermeasures for the reasons.

Analysis of the reason why the pad is easy to fall off when the board is soldered:

1. Material quality issues. Since the adhesion of the resin glue between the copper foil of the copper clad laminate (CCL) and the epoxy resin is relatively poor. In this case, even if the copper foil of a large area is slightly heated or under mechanical external force, it is very easy to separate from the epoxy resin, causing problems such as peeling of the pad and falling off of the copper foil.

2. The influence of storage conditions on the board. Affected by the weather or stored in a humid place for a long time, the moisture absorption of the circuit board is too high. In order to achieve the desired welding effect, it is necessary to compensate for the heat taken away by the moisture volatilization when soldering, the temperature and time of the welding must be extended. Such soldering conditions easy cause the copper foil and the epoxy resin are delamination.

3. Electric soldering iron welding problem, the general circuit board adhesion can meet the ordinary welding, there will be no peeling off the phenomenon of the pad, but the electronic products are generally likely to be repaired, the repair is generally repaired with electric soldering iron, due to the local high temperature of the soldering iron often reaches a temperature of 300-400 degrees, causing the local temperature of the pad to be too high, and the resin glue under the copper foil of the pad is detached at a high temperature, and the pad is detached. When the soldering iron is removed, it is easy to attach the physical force of the soldering iron to the pad, which is also the cause of the falling off of the pad.

For the pad to fall off easily under the conditions of use, the circuit board factory adopts the following aspects to improve the welding resistance of the circuit board pad as much as possible to meet the needs of customers.

1. Use copper clad laminates from manufacturers with quality assurance.

2. The circuit board is vacuum-packed before leaving the factory, and the desiccant is placed to keep the circuit board in a dry state.

3. For the thermal impact of the soldering iron on the pad, we increase the thickness of the pad copper foil by electroplating as much as possible, so that when the soldering iron is heated to the pad, the thermal conductivity of the copper foil thick pad is obviously enhanced, effectively reducing the local high temperature of the pad, and at the same time, the heat conduction makes the pad easier to disassemble, increase the solder resistance of the pad.