Tutorial For PCB Desoldering

1. Basic principles of desoldering:

Be sure to make clear the characteristics of the original welding point before desoldering, do not start easily.

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

(2) The pads and printed conductors on the PCB shall not be damaged during desoldering;

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

(4) Try to avoid moving the position of other original devices, if necessary, must do a good job of recovery.

2. Main points of desoldering:

(1) Strictly control the temperature and time of heating to avoid damage to other components by high temperature.

Generally, the time and temperature of desoldering are longer than that of welding.

(2) Do not overexert when desoldering.

The packaging strength of components decreases at high temperatures, and excessive pulling, twisting, and twisting will damage components and pads.

(3) Absorb the solder on the solder joint.

The solder can be absorbed with the solder absorber tool, and the components can be directly unplugged to reduce the soldering time and the possibility of damage to the PCB.

3. Demoldering method:

(1) Point desoldering method

For the resistance and capacitance components installed horizontally, the distance between the two solder spots is far, the electric soldering iron can be used for point heating and point pulling out. If the pin is bent, use the soldering iron head to pry straight and then remove it. During desoldering, the PCB is erected, and the solder joint of the pin of the component to be dismantled is heated with the electric soldering iron, and the pin of the component is clamped with forceps or needle-nosed pliers and gently pulled out.

(2) Centralized desoldering method

Because each pin of the discharge resistor is welded separately, it is difficult to heat it at the same time by using the electric soldering iron. A hot air welder can be used to heat several welding points quickly, and the solder can be pulled out once after melting.

(3) Reserved desoldering method

Use a solder absorber to absorb the solder from the disassembled solder. In general, the components can be removed. If you encounter multi-pin electronic components, you can use the electronic heat fan for heating. If it is a lap welded component or pin, you can dip the flux on the solder joint and open the solder joint with an electric soldering iron. The pin or lead of the component can be removed.

If it is hook welding components or pins, first remove the solder with the electric soldering iron, then heat with the electric soldering iron, the residual solder under the hook to melt open, at the same time must be in the direction of the hook line with the shovel up the pin. Do not use too much force when prying, to prevent the molten solder from splashing into the eyes or clothes.

(4) Shear desoldering method

If the pins and wires of the components on the dismantled solder joints are surplus, or if the components are damaged, the components or wires can be cut off first, and then the wire ends on the solder pads can be removed.