PCBA Tech - The reason why the pad is soldered off the circuit board? Why is the pad easy to fall off when the circuit board is soldered?

In the production process of PCBA,PCBA solderability is poor, and sometimes PCBA pads fall off. We may directly think that it is due to PCB production problems, but in fact the reason is not so simple. Next, PCBA soldering Analyze the cause of the disk falling off.

Temperature is too high. Generally, double-sided boards or single-sided boards are more likely to fall off the pads. Multilayer boards have a large area of ground, fast heat dissipation, and require high temperatures during soldering, and they are not so easy to fall off. It also has something to do with the quality of the board.

The reason why the pad is soldered off the circuit board:
1. Repeatedly soldering a point will solder the pad;

2, the soldering iron temperature is too high, it is easy to solder the pad;

3, the soldering iron tip exerts too much pressure on the pad and the soldering time is too long, and the pad will be soldered;

4. The quality of the printed board is too poor.

During the use of the circuit board, the pads often fall off, especially when the circuit board is repaired. When using an electric soldering iron, it is very easy to cause the pad to fall off. The circuit board manufacturer has made some suggestions on the reasons for the fall off of the pad in this article. Analyze and take corresponding countermeasures for the reasons.

The reason why the pad is easy to fall off when the circuit board is soldered:
1. Board quality problems.

Due to the poor adhesion of the resin adhesive between the copper foil of the copper clad sheet and the epoxy resin, even the large area of the copper foil of the circuit board copper foil is very easy to interact with the epoxy resin when it is slightly heated or under mechanical external force. The separation leads to problems such as peeling off the pad and the copper foil.

2. The influence of circuit board storage conditions.

Affected by the weather or stored in a damp place for a long time, the circuit board absorbs moisture too high. In order to achieve the ideal welding effect, it is necessary to compensate for the heat taken away due to the volatilization of moisture during the patch welding, and the welding temperature and time must be extend. Such soldering conditions are likely to cause delamination between the copper foil of the circuit board and the epoxy resin.

3, soldering iron problem

Generally, the adhesion of the circuit board can meet the requirements of ordinary soldering, and there will be no pad falling off. However, electronic products are generally likely to be repaired. The repair is usually repaired by soldering with an electric soldering iron. The local high temperature of the electric soldering iron often reaches 300-400 degrees., Causing the local temperature of the pad to be too high instantaneously, and the resin glue under the copper foil of the pad will fall off due to the high temperature, and the pad will fall off. When the soldering iron is disassembled, it is easy to attach the physical force of the soldering iron tip to the pad, which is also the cause of the pad falling off.