PCB News - What is the impact on the quality of reflow soldering in the smt factory SMT process?

What is the impact on the quality of reflow soldering in the smt factory SMT process?
Paying attention to the trend of environmental informationization and the development of various environmental protection technologies, PCB factories can start with big data to monitor corporate pollution and governance results, and find and solve environmental pollution problems in a timely manner. Keep up with the production concept of the new era, continuously improve resource utilization, and realize green production. Efforts to enable the PCB factory industry to achieve an efficient, economical and environmentally friendly production model, and actively respond to the country's environmental protection policy.
During the reflow soldering process in the smt factory, some quality problems sometimes occur, which reduces the product yield. So what are the factors that affect the quality of reflow soldering? The editor will give you an introduction.

1. The influence of solder paste

The quality of reflow soldering in smt factory patch is affected by many factors. The most important factor is the temperature profile of the reflow oven and the composition parameters of the solder paste. Nowadays, the commonly used high-performance reflow soldering furnaces can easily and accurately control and adjust the temperature curve. In contrast, in the trend of high density and miniaturization, the printing of solder paste has become the key to the quality of reflow soldering. .

The particle shape of the solder paste alloy powder is related to the soldering quality of narrow-pitch devices, and the viscosity and composition of the solder paste must also be selected appropriately. In addition, the solder paste is generally stored in refrigeration, and the lid can be opened after returning to room temperature when taking it. Special attention should be paid to avoid mixing the solder paste with moisture due to temperature differences. If necessary, use a mixer to stir the solder paste evenly.

2. The influence of reflow soldering process

After eliminating the quality abnormalities of the solder paste printing process and the placement process, the reflow soldering process itself will also cause the following quality abnormalities:

1) Cold welding is usually the reflow temperature is low or the time in the reflow zone is insufficient;

2) The circuit board or components with tin connection are damp, and excessive water content may cause tin explosion to produce tin connection;

3) The temperature rise in the preheating zone of the tin bead is too fast (generally required, the slope of the temperature rise is less than 3 degrees per second);

4) Cracks are generally caused by the temperature drop in the cooling zone too fast (generally, the temperature drop slope of lead soldering is less than 4 degrees per second);

3. The influence of welding equipment

Sometimes the excessive vibration of the conveyor belt of the reflow soldering equipment itself is also one of the factors that affect the quality of the soldering.

The above are the factors that affect the quality of reflow soldering in the smt factory patch process introduced by the editor. I hope to help you! Paying attention to the trend of environmental informationization and the development of various environmental protection technologies,PCB factories can start with big data to monitor corporate pollution and governance results, and find and solve environmental pollution problems in a timely manner. Keep up with the production concept of the new era, continuously improve resource utilization, and realize green production. Efforts to enable the PCB factory industry to achieve an efficient, economical and environmentally friendly production model, and actively respond to the country's environmental protection policy.