How To Remove Solder From Circuit Board
Regardless of your project, you have several ways to remove solder from, or desolder, your circuit board. These ways range from machine-powered tools to manual, but they will all do the job. For most DIY projects, you only need a desoldering pump and braid.
There is also solder wick. Beyond those, there are methods for more specialized tasks and contexts. Either way, tool choice often comes down to pure personal preference.
1.1 Choose a Desolder Method
Regardless of the tool, desoldering comes down only a few simple methods. They all have advantages and disadvantages. Often, the way you choose comes down to what are you desoldering, how big it is, and where is it.
1.1.1 Grinding and Scraping
Your basic desoldering techniques are grinding and scraping the solder away. These techniques will take some time, but they will work most of the time. Plus, you only need a knife, scraper, or pick.
These techniques are also the most controlled and methodical. The trick is all in your technician skills. Fatigue is the only drawback. Because of this, most people reserve grinding to the final surface preparation steps.
1.1.2 Machining and Milling
While you will want to fit your milling machine with a microscope for precision, you can drill away the solder mask from the circuit board. Milling out the solder will take much less time to do that scrapping, but it does require high levels of skill and experience.
The drill bit can dig into the PCB itself, damaging it in the process.
1.1.3 Chemical Stripping
This technique uses a liquid chemical solvent you must apply with a brush or swab. You should only use this technique to remove solder from copper plates or solder surfaces.
Even then, you still want to use masking tape or some other protective material to protect your circuit. The solvent breaks down the solder like a paint stripper, but it will deteriorate the base material if you allow it.
If you must remove solder from a large surface area, then you want to micro blast your PCB.
This technique uses small bench-top systems that propel abrasive materials at the target area through a pencil-shaped hand-piece, which must be flushed away after application. This abrasive material blasts away the coating.
How To Remove Solder From Circuit Board Holes
The above techniques work on surface mounted components, but through-hole soldering requires a much different approach. Fortunately, you have several useful PCB hole desoldering options, regardless if you want to remove a component or want to remove any excess solder.
2.1 Desoldering Bulb, Pump, or Solder Sucker
Also called solder suckers, desoldering bulbs are the current most popular method for remove solder from circuit board holes. After securing and preheating the PCB and hole in a vice or PCB holder, you suck the solder off the board by squeezing and then releasing the bulb from behind the hole.
To prevent damage to the board, you should re-solder your soldering iron now and then as the technique will remove solder from it as well.
You can also get these tools with or without the rubber bulb. In these desoldering pumps, a plunger replaces the bulb, but their operation is identical.
If you cannot use a bulb for any reason, you can try removing the solder from your circuit board holes with a drill or pin vise.
Drilling is another common desoldering method, but you must use a small enough carbon, cobalt, or high-speed steel bit, as most PCB holes are 0.029 inches in diameter. Oversized bits will remove the tracing within the hole, damaging the board.
2.3 Desoldering Braid/Wick
No longer in everyday use, some technicians still swear by the good old desoldering braid. These ropes of tiny woven copper wires wick up any nearby solder once heated. To use the braid, you place new braid on top of the hole or solder and then apply heat until saturated.
2.4 All-in-one solutions
Besides the above methods, you can find a few combo units. These tools meld a desoldering tool to a soldering iron. You can get them with either a desoldering bulb or plunger. These tools let you desolder while keeping one of your hands-frees.
You can even find fully electronic versions of them that will automatically suck the solder for you. There are also a few models that dedicated to removing solder and nothing else.
How To Remove Solder Without Wick
The techniques mentioned above are the most common ways to remove solder from a circuit board, but they are by no means the only way to do it.
For instance, you do not need an actual wick. You need anything that will absorb molten solder. Any fine stranded wire will do such as old CAT5 Ethernet cabling. After stripping off any insulation and twisting the wires together, you follow the standard procedures for using solder wick.
If you need something more efficient, you can dip your homemade wick into solder flux before using it.
If you do not have any stranded cabling around, you can use some thin rod to push out the solder instead. You push the rod through the hold while heating it from the other side, and the rod takes care of the rest.
To prevent soldering the rod instead, you want something that does not readily solder such as carbon pencil lead, stainless steel, or wooden toothpicks.
How To Remove Solder Without a Soldering Iron
Up to now, we presumed that you have a soldering iron and know how to use it. However, what should you do when you do not? For most of these techniques, you do not need an iron. While they do make solder work more comfortable and faster, but they are never necessary.
A soldering iron is little more than a heated piece of metal. Thus, you can substitute it with any other heated piece of metal. Two long, flat head screwdrivers with a propane torch are perfect for this.
Generally, you will have one to use a screwdriver you do not mine discolored, and another one you mind covered in solder.
From there, you have to heat up your iron-replacement screwdriver until it turns red, and then use it as you would use any other soldering iron. You want to do this close enough to the soldering area so you can use the screwdriver before it cools off.
You use the other screwdriver as a wick. Molten solder should adhere readily to a cold screwdriver. Just do not use your screwdriver wick to pick or chip the solder as this can damage your PCB and components. You can heat the screwdriver to clean off the solder.
How To Remove Old Solder
As solder ages, it becomes increasingly more difficult to melt, especially with an essential soldering iron and solder sucker. However, the great thing about solder is that it hasn’t changed since its invention.
Sure, the materials we use have changed to make better connections, but modern solder melts the same way old solder did. That is also how you remove old solder too. You apply a new layer of solder, and eventually, the heat will melt the old stuff underneath.
You then remove it with any of the desolder techniques mentioned above.
How To Remove Solder Flux
Depending on the solder you use, you may see a bit of flux build up around your soldering area. This flux is mostly harmless so that you could leave it there, but you can clean it off with a simple technique.
How this technique works will depend on your solder and flux, so you will want to check the manufacturer’s documentation. Some DIY experts say you can use isopropyl alcohol or distilled water to remove no-clean flux, but that comes with its risks.
You can also use one of the many chemical cleaners for flux on the market. They all come in aerosol cans like hairspray or shaving cream.
After spraying the flux area, you can use a stiff brush and a set of dental picks to clear the flux out of the cracks and crevices. Once you are done, you can use a cotton swab to dry up any remaining cleaner and flux.
You can repeat the process until you remove everything, going as far as using compressed air as needed.
While most old solder will not damage your PCB or circuitry, there are times when you want to clean your circuit board of solder thoroughly. To remove solder, you must use a desoldering tool in conjunction with a soldering iron.
Once you have all your tools ready, then you can start removing the solder from your boards and components. If you need help choosing the right desoldering tool for your project or instructions on how to use it, please feel free to contact us.