PCBA Tech - Desoldering skills and daily problems in PCBA processing

Desoldering skills and daily problems in PCBA processing

With the development of the market economy and the growth in all aspects of life, PCBA processing may not be very familiar to everyone. Today, I will talk to you about the topic of PCBA processing. Do you know what are the methods of desoldering PCBA processing? What are the common problems? The editors of the circuit board factory come to learn more about it.

1. The basic principles of PCBA processing and desoldering:

Be sure to figure out the characteristics of the original solder joints before desoldering, 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 positions of other original components, and if necessary, restore them.

2. Main points of PCBA processing and desoldering work:

(1) 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.

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

(3) Absorb the solder on the desoldering point. You can use the tin suction tool to absorb the solder and unplug the components directly, reducing the time for desoldering and the possibility of damaging the PCB circuit board (multi-layer circuit board).

3. Desoldering method:

(1) Centralized desoldering method

Since the individual pins of the row resistors are welded separately, it is difficult to heat them at the same time with an electric soldering iron. You can use a hot-air welder to quickly heat several welding points, and pull them out at one time after the solder is melted.

(2) Split-point desoldering method

For horizontally mounted resistance-capacitance components, the distance between the two solder joints 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 the tip of a soldering iron to pry it straight before removing it.

When desoldering, stand up the PCB circuit board (multilayer circuit board), heat the pin solder joints of the component to be removed with an electric soldering iron, and use tweezers or needle-nose pliers to grip the component pin and gently pull it out.

(3) Shearing and desoldering method

If there is a margin for the component pins and wires on the unsoldered spot, or if the components are damaged, you can cut off the components or wires first, and then remove the wire ends on the pads.

(4) Keep the desoldering method

Use a suction tool to suck the solder from the unsoldered point first. Under normal circumstances, components can be removed.

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

If it is a lap-soldering component or pin, you can dip flux on the solder joint and open the solder joint with an electric soldering iron. The component pin or wire can be removed.

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

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

(1) Pass through the blocked pad hole;

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

(3) Try to keep the pins and wires of the re-soldered components consistent with the original ones.