Cause analysis of faulty soldering when soldering components with solder wire

Date：2022-06-14 16:21:58Views：900

The solder products industry can be roughly divided into three categories: solder wire, tin bar and solder paste. These three types of products have different operation processes during welding, but they all have their own standard welding process flow and operation steps. If any step is not properly operated, it will lead to some poor welding phenomena, such as false welding and false welding. Today we will mainly talk about the phenomenon of false welding caused by improper welding, False soldering actually means that the solder joint appears to have been welded stably during the welding process, but actually it will fall off when it is touched. So what is the reason for the occurrence of false soldering? Let's analyze:

The reasons for the formation of false soldering are summarized as follows:

1. Due to the different melting points of different solders, different materials of component pins and fixed components, their thermal expansion coefficients are different. With the change of component working temperature, under the force of thermal expansion and cold contraction, the phenomenon of false soldering will occur.

2. Before welding, if the copper coated circuit board is not well de oxidized, coated with anti-oxidation coating and assisted welding, the tin eating effect is not good, and the phenomenon of false soldering will occur. However, the components on the circuit board, such as nickel plated and stainless steel, are not suitable for the selected tin wire, and the tin is not well applied, which will also cause the phenomenon of false soldering.

3. The poor quality of solder itself (especially in lead solder) is also one of the reasons for solder solder solder failure. At the same time, the temperature of the soldering iron head during welding does not reach the temperature that the solder can melt, which will also cause solder failure.

4. One of the core reasons for the false soldering phenomenon in solder wire welding is that the activity of flux (rosin) is invalid, the type is not matched, the content of flux is too small, and the welding materials such as PCB or electronic components are oxidized too much; Then the solder wire manufacturer suggests increasing the content of flux (rosin) in the solder wire or changing a batch of PCB or electronic components to test.

5. In addition to the above points, attention should also be paid to the debugging of the automatic soldering machine equipment. For example, improper debugging, too tight wiring, too short welding time, etc. will lead to the phenomenon of solder welding. In addition, pay attention to the temperature of the soldering iron during manual welding, and select the soldering iron device with automatic temperature adjustment or the equipment of the regular manufacturer for lead-free solder wire There are different melting points of lead solder wires to adjust the parameters of the equipment, and repeated tests to achieve the effect of solid solder, and effectively avoid bad phenomena such as false soldering and false soldering.

To sum up, the factors causing faulty welding can be summarized into two aspects: external and internal. The external factor is that there is no problem in equipment operation and commissioning, and the personnel must be trained to work; The most important internal factor is the selection of raw materials. Whether it is solder raw materials or components raw materials, they should be ordered from regular manufacturers. The preservation of solder and components is also a crucial link. Factors such as oxidation and moisture prevention should be taken into account.