PCB Tech - How to control the quality of reflow soldering?

How to control the quality of reflow soldering?
The reflow soldering process is to remelt the solder paste pre-distributed on the printed board pad to realize the mechanical and electrical connection between the solder end of the surface mount component or the pin and the printed board pad. . We are not unfamiliar with the technology of reflow soldering in the field of electronic manufacturing industry. The components on the various boards of our electronic products must be soldered to the circuit board through the reflow soldering process. The advantage of this process is that the temperature is easier to control, oxidation can be avoided during the welding process, and the cost of manufacturing products is easier to control. There is an electric heating circuit inside this kind of equipment, which heats the nitrogen gas to a high enough temperature and blows it to the circuit board where the component is already attached, so that the solder on both sides of the component is melted and bonded to the motherboard.

1. How to control the quality of reflow soldering, the production process is mainly optimized from these aspects:

1. Set up a scientific reflow soldering temperature curve and do real-time testing of the temperature curve regularly.

2. The welding should be carried out in accordance with the welding direction of the PCB design.

3. Prevent the conveyor belt from shaking during the welding process.

4. The welding effect of the first printed board must be checked.

5. Whether the soldering is sufficient, whether the surface of the solder joint is smooth, whether the solder joint shape is half-moon shape, the condition of tin balls and residue, the condition of continuous soldering and virtual soldering. Also check for changes in the color of the PCB surface, etc. And adjust the temperature curve according to the inspection results. The welding quality should be checked regularly during the whole batch production process.

6. Regular maintenance of reflow soldering. Due to the long-term operation of the machine, organic or inorganic contaminants such as solidified rosin are attached. In order to prevent secondary pollution of the PCB and ensure the smooth implementation of the process, regular maintenance and cleaning are required.

2. In the maintenance of reflow soldering, how should we operate and what should we pay attention to?

1. It is necessary to formulate a maintenance system for reflow soldering equipment. We must do equipment maintenance after using reflow soldering, otherwise it is difficult to maintain the service life of the equipment.

2. Daily inspection and maintenance of all parts should be carried out, and special attention should be paid to the conveyor belt to prevent it from jamming or falling off;

3. When overhauling the machine, shut down and cut off the power supply to prevent electric shock or short circuit;

4. The machine must be stable and must not be tilted or unstable;

5. Regularly clean the reflow soldering furnace, mesh belt, and condenser, and formulate weekly, monthly, and quarterly maintenance plans to ensure the quality of reflow soldering.
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