< on November 25, 2019

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　　With the development of the market economy and the growth of all aspects of life, you may not know much about PCBA processing. Today, I will talk to you about the topic of PCBA processing. Do you know the desoldering methods for PCBA processing? What are the common problems? Let's learn more about it with the editor of the board factory.

　　1. The basic principles of PCBA processing and desoldering:

　　Before desoldering, be sure to figure out the characteristics of the original solder joints, and don't do it lightly.

　　(1) Do not damage the pads and printed wires on the pcb circuit board (multilayer circuit board) during desoldering;

　　(2) Do not damage the electronic components, wires and surrounding components to be removed;

　　(3) For electronic components that have been judged to be damaged, the pins can be cut first and then removed, which can reduce damage;

　　(4) Try to avoid moving the position of other original devices. If necessary, you must do the restoration work.

　　2. Main points of PCBA processing and desoldering:

　　(1) Strictly control the heating temperature and time to avoid high temperature damage to other components. Generally, the time and temperature for desoldering are longer than those for soldering.

　　(2) Do not use excessive force when desoldering. The packaging strength of components under high temperature decreases, and excessive pulling, pressing and twisting will damage components and pads.

　　(3) Absorb the solder on the desoldering point. You can use a tinning tool to absorb the solder and unplug the components directly, reducing the desoldering time and the possibility of damaging the pcb circuit board (multilayer circuit board).

　　PCBA patch processing

　　PCBA patch processing

　　3. Desoldering method:

　　(1) Centralized desoldering method

　　Since the pins of the resistor row are soldered separately, it is difficult to heat them at the same time with an electric soldering iron. You can use a hot air soldering machine to quickly heat several solder joints, and pull them out at one time after the solder is melted.

　　(2) Point desoldering method

　　For horizontally installed RC components, the distance between the two solder joints is relatively far, and an electric soldering iron can be used to heat them in points and pull them out point by point. If the pins are bent, pry them straight with a soldering iron tip before removing them.

　　When desoldering, erect the pcb circuit board (multi-layer circuit board), while heating the pin solder joints of the components to be removed with an electric soldering iron, use tweezers or needle-nose pliers to clamp the component pins and gently pull them out.

　　(3) Shearing and desoldering method

　　If the component pins and wires on the desoldered point have excess, or determine that the components are damaged, you can first cut the components or wires, and then remove the wire ends on the pads.

　　(4) Retain the desoldering method

　　Use a de-soldering tool to absorb the solder from the soldered joints first. Components can usually be removed.

　　If you encounter multi-pin electronic components, you can use an electronic hot air blower for heating.

　　If it is a lap-soldered component or pin, you can dip the flux on the solder joint, use an electric soldering iron to solder the solder joint, and the component's pin or wire can be removed.

　　If it is a hook-welded component or pin, first use an electric soldering iron to remove the solder from the solder joint, and then heat it with an electric soldering iron to melt the residual solder under the hook, and at the same time, use a shovel to lift the pins in the direction of the hook line. Do not use too much force when prying to prevent splashing melted solder into your eyes or on your clothes.

　　4. Problems that should be paid attention to when re-soldering after PCBA chip processing and desoldering

　　(1) Pass through the blocked pad hole;

　　(2) The moved components are restored to their original state. ;

　　(3) Keep the re-soldered component pins and wires as original as possible.

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