The selection of Solder Paste directly affects SMT production quality. Leaded Solder Paste has good fluidity at high temperatures and can effectively reduce cold solder joints, but its lead-containing characteristics have gradually been restricted by environmental regulations. While lead-free solder paste complies with the RoHS standard, it has a higher melting point and imposes stricter requirements on the temperature control accuracy of Reflow Soldering equipment.

In actual production, it has been found that when using leaded solder paste, the uniformity of solder paste printing and slump control are relatively easy. Especially for fine-pitch components, its wettability performance is superior to that of lead-free solder paste. However, with the tightening of environmental protection policies, more and more enterprises are beginning to transition to lead-free alternatives.

Lead-free solder paste requires a higher preheating temperature and longer holding time during the soldering process; otherwise, problems such as solder joint embrittlement or Flux residue are prone to occur. Meanwhile, its solder ball formation rate is approximately 15% to 20% lower than that of leaded solder paste, which needs to be optimized by adjusting stencil aperture dimensions and squeegee pressure.

In procurement decisions, the cost of leaded solder paste is usually lower than that of lead-free products. However, in the long run, the environmental compliance advantages of lead-free solder paste are gradually emerging, especially in export orders, where customers' environmental requirements have become a key consideration.

For existing production lines, if the equipment supports lead-free soldering, it can be gradually replaced with lead-free solder paste. However, process verification must be carried out in advance, including temperature profile debugging, Solder Joint Strength testing, and appearance inspection, to ensure stable yield during the transition process.

The final selection should be determined based on specific application scenarios. For example, high-reliability military products may still use leaded solder paste, while consumer electronics products prioritize lead-free solutions. At the same time, it is necessary to consider the supplier's technical capabilities and localized service response speed.

In practical operations, it is recommended to first verify the adaptability of lead-free solder paste through small-batch trial production, and then gradually expand the application scope to avoid batch scrap caused by immature processes.

Whether it is leaded or lead-free solder paste, its storage conditions, usable time after opening, and printing parameters must be strictly followed; otherwise, solder joint defects are easily caused, affecting the overall product quality.