Desoldering

- an overview of how soldered joints can be unsoldered or desoldered.

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Soldering Tutorial Includes:
Soldering basics Manual soldering: how to solder Soldering irons Tools for soldering Solder - what it is and how to use it De-soldering - the secrets of how to do it properly Solder joints PCB solder resist

While being able to make good solder joints is very important, another skill that can be equally important is knowing how to de-solder well. Every electronic project will have one problem or another and often this will involve de-soldering a joint. It could be that a wrong component has been used, the circuit needs changing, or a soldered joint is not satisfactory. If any de-soldering is not done well, then it can damage a printed circuit board or components, leading to costly or time consuming rebuild.

De-soldering a joint may not be easy. Coupled to this, if heat is applied to the joint for too long, it is likely to damage the printed circuit board, if one is used, or it can easily damage a component. It is therefore necessary to tackle any jobs with care, and by using the right tools.

Solder pumps / solder suckers

The main tool used for de-soldering is a form of suction pump. Commercial de-soldering stations have a foot operated electrical pump, but for most home enthusiasts, this will be far too expensive. Instead a spring loaded pump is used. These de-soldering tools are spring loaded and have a plunger that is pushed in to "load" it. A small button is pressed to released the plunger which then draws in air through a small PTFE nozzle. The suction this causes is sufficient to suck the solder off the joint. As a result these tools are often called solder suckers.

Even though the nozzles of these pumps are made from PTFE, they still need replacing from time to time. Additionally the pumps need to be cleaned as they draw in the solder each time. Occasionally it is also necessary to clear the nozzles as these can become blocked with solder. When this occurs the action of the pump is greatly reduced.

The big drawback of these pumps is that they have a recoil. As the plunger moves in one direction, there is a tendency for the rest of the pump to move in the other. This can sometimes knock or jolt the work piece. It also can make it slightly difficult to keep the pump in the correct place so that it can remove all the solder.

Solder braid

Another way of removing solder from an area is to use solder braid or de-soldering braid. This is also sometimes called "Solder Wick". Despite any first thoughts, this works amazingly well. The product consists of a fine copper braid that is impregnated with some flux.

When applied to a solder joint the solder is then drawn into the braid by capillary action. It leaves the joint much cleaner and free from solder than if a solder pump had been used. However it is obviously more costly. Accordingly it is often better to remove most of the solder using a solder pump, and then if required the last remnants of solder can be removed using the braid.

Apart from the fact that each piece of braid can only be used once, the main drawback is that without care, it is possible to solder the braid to the joint. This can result in damage if a solder pad is delicate, and it can result in pads being lifted. The remedy is simple - make sure that the soldering iron and braid are removed together.

Practice

In the same way that soldering requires practice to gain the best results, so to does de-soldering. In some ways de-soldering can be more difficult, but with care and practice (which will certainly happen in any project as nothing ever goes to plan), it will be possible to make a very good job of de-soldering and removing components.