Solder paste is a type of soldering material commonly used in the SMT production industry. It is a paste-like solder made by uniformly mixing alloy powder with a flux carrier. Many PCB manufacturers have reported that solder paste easily dries out during the production process. Next, we will introduce the reasons and solutions for solder paste drying out easily.
Firstly, solder paste used in the reflow soldering process has a smaller area of application compared to solder paste in the solder paste container, making it more prone to hardening. This can result in the solder paste not melting properly, causing poor soldering of the joints. Additionally, trace amounts of solder paste conduct heat more easily, making it less likely to melt at high temperatures. Therefore, adjusting the reflow soldering temperature curve slightly or conducting soldering in a nitrogen environment are effective solutions.
Secondly, solder paste hardening can also be attributed to the volatile flux contained in its composition. The flux with the highest content in solder paste is typically rosin, which contains a large amount of rosin acid that can lose activity at high temperatures. Therefore, it is essential to control the soldering process temperature, ensuring it stays around 200°C, as temperatures that are too high or too low are not suitable. Moreover, the quality of the flux can also affect solder paste hardening. Poor-quality flux can affect the viscosity of the solder paste, making it more prone to drying out. Therefore, selecting high-quality solder paste can fundamentally solve the problem of solder paste hardening.
Additionally, external factors such as the usage scenario, humidity, temperature, etc., can also affect the occurrence of solder paste hardening and not melting. Therefore, attention should also be paid to these external factors. We hope these methods can help solve your problem.