Desoldering

Some situations may require you to desolder a component. Maybe a component is defective and requires replacement, or maybe you want to reuse a component for a different keyboard.

Desoldering can be tricky, as the process is prone to causing damage to your keyboard or its components. This page contains some tips and tricks to help you navigate through desoldering parts.

Tools

Tools such as a solder sucker or desoldering braid will help you here. Both are affordable tools and are useful to have in your toolkit. Some of the steps on this page use these tools, though it's often possible to desolder without these tools.

If you have it, flux can help in removing oxidation from old joints. In a pinch, flux-core solder also contains flux, so applying a bit of solder to a joint you want to desolder can help speed up melting it.

Desoldering is the process of removing joints. If there's only a single joint, you could just heat that up and lift the component out - relatively easy. However, usually there are two or more joints to heat up, which requires a little finesse. Here are some techniques you can apply to make desoldering easier.

Wiggle

Wiggling is useful when removing components that only have two leads, including switches, diodes and resistors.

Heat up one of the leads, and try to bend the component in such a way that the lead moves away from the PCB a little. There's no need to move it all the way: just a little is fine.

After the lead has moved, keep holding the component until the solder has solidified again. You can now let go of the component, and it will stay in its new, slightly angled position.

Next, heat up the other joint, and move the component again to move its other lead away from the PCB. Let the solder cool.

You can repeat this series of heating up, moving the component and letting the solder cool to slowly but surely wiggle the component up and away from the PCB. Eventually, it'll be removed from the PCB entirely and you can now place a new component.

It can be easier to place a new component after removing the remaining solder from the joint. You can use your solder sucker or desoldering braid for that purpose.

Adding solder

If a joint won't melt, and if adjusting your soldering iron's temperature won't cut it, you can try this easy trick: just apply a little bit of extra solder!

The extra solder will be easier to melt, and due to the extra surface area it creates, it will be easier to melt the joint as well.

Extra solder also adds some mass to the joint, causing it to cool off more slowly. It can help to add solder just to give you more time to work with, which can be helpful when desoldering components with more leads such as OLED displays.

Bridges

Especially for components with small pads, such as the SK6812MINI-E RGB LEDs, you can add some extra solder to bridge two pads on purpose. This way, you can heat up two pads in the same action, so you can apply the wiggle technique to more complex components as well.

Do mind that when desoldering fragile components such as RGB LEDs, the heat will usually destroy the component, so you may not be able to reuse it. You'll usually only desolder such a component when it already doesn't work, though.

After removing the component, be sure to remove the excess solder as to not cause an accidental short. In most situations, two neighbouring pads should never be connected.

Removing solder

To remove solder, you'll need either a solder sucker, desoldering braid or both. A solder sucker simply sucks up molten solder, while desoldering braid uses capillary force to move molten solder into it as it's heated up.

Using a solder sucker

A solder sucker is used for coarse, rough work. It applies a lot of sudden suction force and may suck in nearby loose SMD components when you're not careful. It is often used for desoldering through-hole components, and for removing larger blobs of solder.

Arm the solder sucker by pushing the button attached to a spring all the way down. Usually it's a big button on the opposite side of the tip.

Once armed, heat up the joint you want to desolder, and hold the solder sucker with its tip next to the joint. Once the joint has molten, press the button on the side of the solder sucker, and the spring will jump right up, sucking air into the sucker, and the molten solder along with it.

You may have to repeat this process a few times.

If some solder is stubborn, it can help to add some solder to the joint first, giving it some more body for the solder sucker to work with.

Don't forget to clean your solder sucker from time to time.

Using desoldering braid

Desoldering braid is usually used for more precise work and for removing smaller volumes of solder.

To use desoldering braid, roll off a little length from the spool, such as 10cm (4 inches). You can let it hang from the spool while using it. While working with it, you can hold the braid by its spool.

Bring the braid to the joint you want to desolder, then poke the tip of your soldering iron to the joint, with the braid between the joint and your soldering iron's tip. It will take longer to melt the joint than you're used to, because the braid also leeches considerable heat, which is needed for its effect to work. You may need to (greatly) increase the temperature of your iron to work with the braid.

Hot! Desoldering braid works by heating it up. Desoldering braid is made of copper, which conducts heat quite well. Don't touch the copper while working with it, it can be hotter than you'd expect!

When using braid, be careful when applying force! There is never a need to apply much force with your soldering iron: just poking at the braid and the underlying joint is enough! When you need to move the braid, lift it up first, and then bring it down again, instead of dragging it over the PCB. Because braid requires working at a higher temperature, the risk of damaging a pad is very large if you do apply excess force.

After a while, you'll see the brown copper slowly becoming more silver as it sucks up solder from the joint. If a spot of braid has become entirely silver, it won't suck up more solder, so while still heating the braid, pull it and your solder iron away from the joint, and move in a fresh piece of braid to capture the rest of the solder.

You can cut off silver spots of your braid using a flush cutter, after which you should dispose of them. Used lengths of braid are not reusable.

Braid getting stuck? It happens to the best of us: the braid can get stuck to your iron, or to the PCB. When that happens, increase the temperature of your iron. If it's still stuck, try to feed some extra solder near the point where it's stuck. That'll usually do the trick. Don't pull the braid away, especially if the braid is stuck on your PCB - you're sure to lift a pad, which is annoying to fix.

The component is still stuck after removing solder

If you've removed solder and want to remove the component, you may find that it's still stuck.

There can be solder remaining on the other side of the PCB, or there can be trace amounts of solder left that still keep the component clinging to the PCB.

Again, don't apply force. Applying force may work, but the risk of ripping a pad off the PCB is too great to be worth it.

If a component is stuck, try the earlier techniques again after applying some solder to the joint that's stuck. Wiggle it out, apply bridges if necessary, or try to remove solder again. Applying brute force will only make the situation worse.

Soldering healthy joints

Being able to form quality joints make for a long-lasting, reliable project.

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