How to Remove Solder
The whole point of soldering is to form a strong, permanent connection between wires, circuits, and other components, but sometimes a soldering job goes wrong, a circuit board bridge needs to be removed, or a component breaks and needs to be replaced. That's where solder removal, or desoldering, comes into play.
If you're comfortable with soldering in general, then you'll probably find desoldering to be a relatively easy task. Removing a solder joint is more or less the exact opposite of creating one: instead of melting solder into place to create a connection, you melt down an existing solder joint to break a connection, and then clear the old solder away.
Sounds pretty straightforward, right? It is. There are just two tricks to mastering the art of desoldering: using the right tools, and learning a few simple techniques. Below, you'll find quick and easy tips on the 3 most common methods of desoldering.
First Things First: Eye Protection
No matter which desoldering method you decide to use, remember that they all involve your face being in very close proximity to molten metal. When you melt down a solder joint, wires and other joined components can suddenly "snap" apart from each other as the bond loosens, and this can send very small (but extremely hot) droplets of solder flying in your direction. Before firing up your soldering iron, always put on a pair of safety glasses – it's all fun and solder removal until somebody puts an eye out.
The Solder Pump Method
A solder pump, also known as a solder vacuum or even "solder sucker," is a small, handheld suction device that's used to vacuum up small amounts of liquefied solder as you melt down joints. There are a few electrically-powered versions of this tool on the market, but many pros and hobbyists rely on the manual type, which uses the release of a compressed spring to create a brief but strong suction that rapidly removes melted solder from your work surface.
- Set the spring of your solder pump.
- Gently touch the tip of a preheated soldering iron to the solder bead or joint that you need to remove; keep the soldering iron in place until the solder begins to flow.
- Leaving the soldering iron in place, bring the tip of your solder pump very close to the melted solder, so that the two are almost touching.
- Push the release button, which will create a quick blast of suction that should cleanly remove any molten solder in the immediate area.
- Give the melted solder a minute to cool inside the suction device, and then clear the solidified solder debris from the pump (this can usually be done right through the pump's tip).
The Desoldering Iron Method
This technique is so much like the method above that it doesn't take much explaining. The only difference is that it uses a one-piece desoldering iron instead of a separate soldering iron and solder pump. A desoldering iron is basically just a soldering iron with a built-in vacuuming component that suctions away the old solder as soon as it's melted. It's not an absolute must-have for removing solder, but can make the job a lot easier, thanks to the fact that it can be operated with one hand.
There are many different models of desoldering irons available, and like solder pumps, they pretty much all fall into one of two categories. Some are fully powered for both soldering and suction; this type has a constantly running, electrically-powered solder pump that continues to vacuum automatically as long as the iron is in use. These tend to be a little higher in price, and are most commonly used by professional electronics manufacturers.
On the other hand, there's the semi-powered version, which uses electricity or gas to heat the desoldering iron's tip, but suctions via a manually-operated aspirator bulb mounted to the iron. Its simpler design makes this type of desoldering iron much more affordable, so it's a favorite with hobbyists and other less-frequent desolderers.
As for the process? It's easy – much like the steps in the section above…
- If you're using a fully powered desoldering iron, heat it up as you would a standard soldering iron, and with the vacuum running, apply the tip to the solder joint being removed. As the solder liquefies, it will automatically be suctioned away by the running solder pump.
- When removing solder with manual-pump desoldering irons, preheat the iron, apply its tip to the joint, and hold it in place until the solder begins to flow. When this happens, simply squeeze the aspirator bulb mounted to the iron, and the solder will be suctioned away.
The Desoldering Braid Method
Desoldering braid, also known as solder wick, is a cord-like product that's woven out of very fine copper wires, and uses capillary action to wick away molten solder during the desoldering process. Solder wick comes on a spool, and while it's slower at removing solder than the typical solder pump, it's also very effective.
- Choose the correct size desoldering braid by measuring the diameter of the solder joint you'll be removing, and then using solder wick that's the same width or slightly wider.
- Preheat a soldering iron. When it's reached the correct temperature, lay the desoldering braid over the joint, and then apply the soldering iron's tip to it. Because solder wick is copper, it will quickly absorb the iron's heat and transfer it to the joint below. As the solder joint melts, you'll see the molten metal soaking into the copper braid and turning it a tin color.
- Continue to press on the joint, through the braid, until all of the flux has been wicked away. If the flux fully saturates one section of the braid before the job is done, move to a clean section and continue desoldering until the joint is completely removed and absorbed.
- When all the molten solder has been removed, carefully remove the soldering iron and solder wick. Be sure to lift the desoldering braid and hot iron together, in one movement; moving the soldering iron away before the wick can cause the solder-filled braid to rapidly cool off and solidify back onto the project.