PCB Tech - Precautions for manual welding in PCBA processing

Matters needing attention during PCBAmanual soldering:

1. It must be operated with an electrostatic ring, the human body can generate static electricity above 10,000 volts, and the IC will be damaged when the voltage is above 300 volts, so the static electricity of the human body needs to be discharged through the ground wire.

2. Wear gloves or finger cots to operate, and bare hands cannot directly touch the machine board and the golden fingers of the components.

3. Perform welding with the correct welding temperature, welding angle, and welding sequence to maintain proper welding time.

4. Take the PCB correctly: When taking the PCB, hold the edge of the PCB, and don't touch the components on the board.

5. Try to use low-temperature soldering: high-temperature soldering will accelerate the oxidation of the soldering iron tip and reduce the life of the soldering iron tip. If the temperature of the soldering iron tip exceeds 470°C. Its oxidation rate is twice that of 380°C.

6. Do not apply too much pressure when soldering: Do not apply too much pressure when soldering, otherwise the tip of the soldering iron will be damaged and deformed. As long as the soldering iron tip can fully contact the solder joints, heat can be transferred. (Choose different soldering iron tips according to the size of the solder joints, which can also make the soldering iron tips better heat transfer).

7. Do not knock or shake the tip of the soldering iron when soldering: knocking or shaking the tip of the soldering iron will damage the heating core and the tin bead spattering, shortening the service life of the heating core. If the tin bead splashes on the PCBA, it may form a short circuit and cause Poor electrical performance.

8. Use a wet water sponge to remove the soldering iron tip oxide and excess tin dross. The water content of the cleaning sponge should be appropriate, and the water content can not completely remove the solder swarf on the soldering iron tip, but also because of the sharp drop in the temperature of the soldering iron tip (this Thermal shock damages the soldering iron tip and the heating elements inside the soldering iron greatly), resulting in poor soldering such as missed soldering and false soldering. The water on the soldering iron tip sticks to the circuit board, which will also cause the circuit board to corrode and short-circuit. Too little or no wet water treatment will damage the soldering iron tip, oxidize and cause no tin, and it is also easy to cause poor soldering such as false soldering.

Always check that the water content in the sponge is appropriate, and clean the tin slag and other sundries in the sponge at least 3 times a day.

9. When soldering, the amount of tin and flux should be appropriate. Too much solder can easily cause tin connection or cover welding defects. Too little solder not only has low mechanical strength, but also the surface oxide layer gradually deepens over time, which will easily lead to solder joint failure. Too much flux will pollute and corrode the PCBA, and may cause electrical defects such as leakage. Too little will not work.

10. Always keep the soldering iron tip tinned: This can reduce the chance of oxidation of the soldering iron tip and make the soldering iron tip more durable.

11. The incidence of flux spatter and solder balls is related to the proficiency of the soldering operation and the temperature of the soldering iron tip; the problem of flux spatter during soldering: When the solder wire is directly melted with a soldering iron, the flux will rapidly heat up and splash. When soldering, use solder The method that the wire does not directly touch the soldering iron can reduce the splashing of the flux.

12. PCBA manual soldering, be careful not to burn the plastic insulation layer of the surrounding wire and the surface of the components with the electric soldering iron, especially the products with compact soldering structure and complicated shape.