In PCBA processing, if the soldering quality of the electronic components is found to be inadequate, it is necessary to perform desoldering operations on the electronic components that are not soldered. However, without damaging other components and PCB boards, if you want to remove the wrong soldered electronic components, you must master skilled desoldering skills.

What are the precautions for desoldering? The following Sanjing will introduce to you:

Be sure to clarify the characteristics of the original solder joints before desoldering. Do not damage the components, wires and surrounding components to be removed; do not damage the pads and printed wires on the PCB during desoldering. For electronics that have been judged to be damaged For components, the pins can be cut off before removal, which can reduce damage; try to avoid moving other components, if necessary, be sure to do a good job of restoration.

When desoldering, strictly control the heating temperature and time to avoid high temperature damage to other components. Generally, the time and temperature of desoldering is longer than that of soldering. Handle with care when desoldering. The package strength of components under high temperature will decrease. If the operation is too hard, the components and pads will be damaged. You can use a suction tool to suck the solder on the desoldering point, and unplug the components directly, reducing the desoldering time and the possibility of damaging the PCB.

There are several methods of desoldering, such as split-point desoldering method, centralized desoldering method, reserved desoldering method, cut off desoldering method, etc. The following Sanjing will be introduced for everyone:

1. Split-point desoldering method: For the resistance-capacitance components installed in the bedroom, the distance between the two soldering points is relatively long, and an electric soldering iron can be used for heating at points and pulling out point by point. If the pin is bent, use a soldering iron tip to pry it straight before removing it. When desoldering, the PCB is erected, while heating the pin solder joints of the component to be removed with an electric soldering iron, while holding the pin of the component with tweezers or needle-nose pliers, gently pull it out.

2. Centralized desoldering method: Since each pin of the row resistor is welded separately, it is difficult to heat it at the same time with an electric soldering iron. You can use a hot-air welder to quickly heat several solder joints, and pull out once the solder is melted. 

3. Keep the desoldering method: first suck the solder from the unsoldered joint with a suction tool. Under normal circumstances, you can remove the components. If you encounter multi-pin electronic components, you can use an electronic hot air blower to heat it. If it is lap-welded components or pins, you can dip flux on the solder joints, open the solder joints with an electric soldering iron, and the component pins or wires can be removed. If it is a hook-welded component or pin, first remove the solder from the solder joint with an electric soldering iron, and then heat it with an electric soldering iron to melt the residual solder under the hook, and at the same time use a spatula to lift the pin in the direction of the hook line. It should be noted that excessive force should not be used when prying to prevent the molten solder from splashing into the eyes or clothing.

4. Cut and desolder method: If there is a margin for the component pins and wires on the desoldered point, or if the components are determined to be damaged, you can cut off the components or wires first, and then remove the wire ends on the pads .

However, when re-soldering after desoldering, pay attention to the re-soldering component pins and wires as much as possible to keep the same as before, clean the blocked pad holes in time and restore the moved components to their original state.

The above is about the precautions and methods of PCBA processing and desoldering, I hope it can be helpful to everyone!