What are the reasons why the soldering station is not fully welded?
In the process of soldering lead-free solder paste, we often see some unsoldered phenomena: solder bridges are formed between adjacent leads. Why is there such a problem? Today, solder paste manufacturers will tell you about:
Typically, solder paste slump can be caused by a variety of reasons, including:
1. The furnace temperature rises too fast;
2. The thixotropy of lead-free solder paste is too poor or the viscosity recovers slowly after shearing;
3. The metal load or solid content is too low;
4. The particle size distribution of the powder is too wide;
5. The surface tension of the flux is too small.
Apart from the causes of solder paste slump, there are also some factors that are also common causes of under-soldering:
1. Compared with the space between solder joints, there is a lot of solder paste deposition;
2. The heating temperature is too high;
3. The heating speed of the solder paste is faster than that of the circuit board;
4. The flux wetting is too fast;
5. The vapor pressure of the flux is too low;
6. The solvent content of the flux is too high;
7. The softening point of the flux resin is too low.
Special Note: When the lead-free solder paste reflows, under the promotion of surface tension, the molten solder may break, and the loss of solder will make the problem of unsoldered more serious. In this case, excess solder accumulated in a certain area due to solder loss will make the molten solder too much to disconnect easily.
