What are the factors affecting the quality of reflow soldering

Reflow soldering is the back-end equipment of SMT chip processing. It mainly melts the solder paste at high temperature to fasten the electronic components and the pad, which is not easy to fall off. Generally, reflow soldering has four temperature zones, namely preheating zone, insulation zone, welding zone and cooling zone. The functions and temperatures of different temperature zones are different. Therefore, the quality of product reflow soldering has a great relationship with the factors of reflow soldering.

1. Influencing factors of solder paste

The quality of reflow soldering is affected by many factors. The most important factors are the temperature curve of reflow soldering furnace and the parameters of solder paste The particle shape of solder paste alloy powder is related to the welding quality of narrow spacing devices, and the viscosity and composition of solder paste must also be selected appropriately In addition, the solder paste is generally stored in cold storage. When taking it, the cover can be opened and stirred until it returns to the room temperature. Pay special attention to the water vapor mixed into the solder paste due to the temperature difference. Mix the solder paste with a mixer when necessary.

2. Impact of equipment

Excessive vibration of the conveyor belt of reflow soldering equipment is one of the factors affecting the welding quality.

3. Influence of reflow soldering process

After excluding the abnormal quality of solder paste printing process and patch process, the reflow process will also lead to abnormal quality.

1. Cold welding is usually reflow welding with low temperature or insufficient circulation time

2. The temperature in the preheating area of tin bead climbs too fast

3. Components are damp and contain too much water, which is easy to cause tin explosion and tin connection

4. The temperature in the cooling area drops too fast