SMT reflow soldering furnace temperature test content

In order to improve the quality of SMT reflow soldering, we all need to test the furnace temperature. The different temperature zones in the four temperature zones of reflow soldering equipment (heating zone, preheating constant temperature zone, reflow soldering zone, cooling zone) have special functions. JEENOCE would like to share the content of SMT reflow soldering furnace temperature testing.

1、 Reflow soldering furnace temperature test: Solder the temperature sensor to the corresponding test point on the PCB according to the operating specifications and procedures of the furnace temperature tester; According to the operating specifications and procedures of the furnace temperature tester, place the furnace temperature tester and PCB on the track of the welding equipment. Run the welding equipment and collect data on the temperature curve of the welding equipment. The data collector of the furnace temperature tester is shown in the figure.

2、 Import the temperature curve data obtained from the data collector of the furnace temperature tester into the furnace temperature tester, and use analysis software to analyze the actual temperature curve. If the actual welding temperature curve does not reach the preset result, the temperature curve should be corrected again. And guide the revised welding procedure back to the welding equipment.

3、 Furnace temperature curve correction: Run the welding equipment again and collect data from the corrected welding temperature curve. And analyze whether it overlaps with the ideal temperature curve.

Finally, there is another important point to pay attention to, which is the issue of cooling zone in SMT surface mount production. The misunderstanding about the cooling zone is that after the board is welded, in order to ensure the stability of the solder joints, the cooling solder paste is solidified to maintain cold stability of the solder joints.

But the fact is that the higher the cooling rate, the better. Consider the cooling capacity of the reflow soldering equipment, the thermal shock that the board, components, and solder joints can withstand. A balance should be sought between ensuring the quality of solder joints without damaging the board and components. The minimum cooling rate should be above 2.5 ℃, and the maximum cooling rate should be above 3 ℃. Considering the thermal shock that components and PCBs can withstand, the cooling rate should be controlled between 6-10 ℃.