The particle shape of the solder paste alloy powder is related to the welding quality of the narrow-pitch device, and the viscosity and composition of the solder paste must also be selected appropriately. In addition, solder paste is generally stored in a refrigerator, and the lid can only be opened after it has returned to room temperature. Special attention should be paid to avoid the solder paste being mixed with water vapor due to temperature difference. When necessary, use a mixer to stir the solder paste evenly.。

Influence of welding equipment

  Sometimes, the excessive vibration of the conveyor belt of the reflow welding equipment is also one of the factors affecting the welding quality。

The effect of reflow soldering process

After eliminating the quality abnormalities of the solder paste printing process and the patch process, the reflow soldering process itself will also lead to the following quality abnormalities:

①Cold welding is usually caused by low reflow temperature or insufficient time in the reflow zone.

②The temperature of the tin bead preheating zone climbs too fast (generally, the slope of the temperature rise is less than 3 degrees per second)。

③Continuous tin circuit boards or components are damp, and too much moisture can easily cause tin explosions to produce tin tins.

④ The crack is generally caused by the rapid temperature drop in the cooling zone (generally, the temperature drop slope of lead soldering is less than 4 degrees per second).