Poor wetting of lead-free Solder Paste frequently occurs in SMT production. Many engineers' first reaction is to suspect the quality of the solder paste, but the actual problem often lies in the process steps.

First, check whether the storage conditions of the solder paste are compliant, and whether the temperature and humidity meet the standards. Improper storage of solder paste will cause the activator to fail, directly affecting the wetting effect.

Secondly, pay attention to whether the printing parameter settings are reasonable. Excessive or insufficient squeegee pressure, or mismatched stencil aperture sizes will cause uneven solder paste deposition, which in turn affects wettability.

Furthermore, check whether the Reflow Soldering profile is accurate. Excessively high or low temperatures, or mismatched heating rates may damage the wetting performance of the solder paste.

In addition, pollution factors in the soldering environment cannot be ignored. Contaminants such as Flux residues and metal dust will hinder the bonding between the solder paste and the pads.

It is recommended to replace the solder paste regularly to avoid performance degradation caused by long-term storage. At the same time, optimize the printing and reflow soldering parameters to ensure process stability.

When encountering poor wetting problems, priority should be given to troubleshooting process parameters, rather than directly attributing the problem to the solder paste itself.

Maintaining equipment cleanliness and environmental control can effectively reduce the incidence of poor wetting.

In actual operation, starting with details is the only way to quickly identify and solve problems.