I would say that desoldering is much harder than soldering. It took me a couple weeks to get good at soldering and several years to get good at desoldering, partly because I didn’t used to do it as often when I first got into electronics, just building circuits from kit PCBs and schematics. Working on old synths though, I have to desolder all kinds of things constantly from different kinds of boards and have refined my techniques pretty well, so I thought I’d share some of what I’ve learned here. This tutorial will be an overview of many desoldering techniques, explaining how to desolder with different tools.

Before the onslaught of details begins, I’ll start by telling you what I think is the most important tip for desoldering in general: it’s always better to remove all the solder from a hole at once. Successful desoldering is always reliant on solder’s affinity for itself. So make sure it really seems like the solder is completely melted all the way through the board (especially if it’s a double-sided board) before applying any suction.

This makes such a big difference that if I desolder a pin and remove the blob of solder from around the lead but find that the inside of the hole in the PCB is still clogged with solder, I will actually add more solder and start over rather than persist in trying to extract the solder from the hole. Figuring out this strategy was a game-changer.

Also, if you are trying to desolder old solder and can’t get it to melt in the first place, try adding some new solder to it first.

Edit: One more tip I forgot to include. It’s often easier to desolder if you can snip the component off before you start desoldering its leads, because the component can act like a heat sink and basically waste the heat you’re applying to it!

Desoldering Tools

Unsurprisingly, it’s really important to choose the appropriate desoldering tool for your situation. Here are some thoughts and explanations on how to use the four most common types of tools, shown above.

Desoldering Bulb – this is the first desoldering tool I acquired. To use it, you compress your bulb with one hand, heat up the solder you need to remove using your soldering iron with your other hand, hold the tip of the bulb close to the melted solder and release. The solder will hopefully be sucked up into the bulb as it sucks in air. You periodically have to pull out the white tip and empty it, or clear out a clogged tip.

It doesn’t offer much suction power but there isn’t really any risk of doing damage from suction either. Nowadays, I only use it when I accidentally add too much solder to a joint and want to carefully remove a specific amount (because you can release it slowly to control how much it sucks), and to be honest even then, I’ll just use braid unless the bulb happens to be somewhere where I can reach it without getting out of my chair. (Just trying to be real.)

Spring-loaded “solder sucker” – when I got this after relying solely on the bulb and rather low-quality braid for a few years, I thought it was the greatest thing. You push down on the spring plunger so it clicks into place, and then once you’ve melted your solder you position it above the joint and press the button and it sucks it up with a pleasing “chook” noise.

There are three problems to this. First of all, it can only suck for as long as it takes for the small chamber to fill up with air again. Third, it can, believe it or not, occasionally suck a solder pad right off the board. And third and worst of all, it has a tendency to spew solder flakes everywhere. You have to clear it out constantly by repeatedly pressing the plunger and then pressing the button in between suctions. (Click chook click chook click chook.) Sometimes, even after doing this, it will still spew out solder flakes at the same instant as it is sucking in your melted solder. These solder flakes can shoot into all areas of your board and cause shorts if you fail to remove all of them. Maybe other people don’t have this problem with it? I don’t know, but for this reason, I never use it anymore.

However, it would be safe to use it in situations where you’re working on a milled copper board with big (i.e. discrete) components, where the board can be fully removed from the instrument– PCBs from a combo organ, for instance.

For the most part, I rely on these two tools:

Desoldering Braid or Wick- this relies on the affinity of fluxed solder for itself– “wicking action.” It is just a woven strip of copper wire infused with flux. To use it, you pin the braid against the solder you want to remove using the tip of your heated soldering iron, and the solder will be pulled up into the braid. I find it kind of enchanting to watch the silver coloration from the solder travel backwards along the braid. If you’re having trouble getting the braid to pull the solder, you can add more flux to it!

When using this, it works best if you have your iron on a fairly hot temperature, at least 675 degrees Fahrenheit but up to 725 depending on the characteristics of the board, so that the solder becomes very liquidy. But you have to be careful not to press your tip directly against the PCB trace or pad at this temperature, always keeping the braid between the tip and the board.

While it is possible to desolder basically everything with braid, as I did for some time, I now usually only use braid for desoldering small areas because it is expensive and desoldering a large area, like the solder holding in a snap-in power supply capacitor, can easily use several inches of braid. After a strip of braid is filled with solder, you have to cut it off and throw it away. But there are some applications where the precision and relative gentleness of braid make it sort of the only option– desoldering large ICs from certain ARPs, for example.

Also, it’s very important to get a good quality braid. If the flux in it is no good for whatever reason, it will barely work. I’ve been very happy using MG Chemicals Super-Wick, which is also great because I can order it on Amazon when I unexpectedly run out and it will show up the next day.

Vacuum Desoldering Station – When I got my Aoyue 474A++ vacuum desoldering station (via Amazon) about two years ago, it basically changed my life. I chose it simply because it is the cheapest vacuum desoldering station available (about $145). I use it almost every day, sometimes for several hours, and have not had any issues with it. There are much more expensive versions of this kind of device available, but I’m not sure what they offer to make them cost 6 times as much.

It consists of a big block of a base unit with a motor inside driving a fan that sucks air through a tube connected to the handheld part, which is gun-shaped and has a conical tip with a hole in it. You set the temperature (in Celsius degrees) on the base of it.

Notes on Solder Flux: before I go into depth on the vacuum desoldering station, I wanted to talk a little about using flux when desoldering. Flux is usually already in lead solder in the form of “rosin” to help it melt and improve its flow and affinity for itself, but you can also apply more flux to the old solder while desoldering to encourage the solder to keep flowing off the board into whatever you’re removing it with. It can be very helpful, especially for two-sided PCBs, when you apply it to both sides of the board.

I hate using flux because I have chronic migraine and the smell of hot flux can be a migraine trigger for me and can make me very nauseous, but it can be very helpful. Adding flux to solder before you desolder it helps the heat travel through it and helps it liquefy, and thus increases the chances of it all melting at once, and all being sucked up at once. I use paste flux on PCBs, and also sometimes use a disposable liquid flux pen to add more flux to braid if I’m trying to desolder something with braid and having trouble. I use flux as little as possible just because it’s so noxious to me, but if you don’t mind using it more often, it may help you a lot.

Flux fumes are very toxic! They will hurt your eyes, your head and probably your brain. If you ever start feeling sick after soldering, the flux in the solder, not the lead, is most likely what’s affecting you. Whenever I am using flux, I open the window in front of my workspace (luckily my work table is directly in front of a window) and put a fan in the window blowing outwards. If you don’t have a window that conveniently located, you can make a rudimentary fume extractor by putting a carbon air filter sheet (like you would put in a stove fan or air purifier) on the back of a box fan and putting that near you (blowing away from you). This is good to do while desoldering or soldering in general, too.

So! More about my beloved vacuum desoldering station

A vacuum desoldering station makes it possible to desolder things quickly and cleanly in a way that is not remotely possible with any of the other tools. It allows me to take on tasks that would be absurd without it. Last week, I removed 43 pots, 44 lighted tact switches and two encoders from a second Quasimidi Polymorph (around 500 leads altogether including a couple hundred snap-in tabs) in just about two hours while watching “funny animal” videos on Youtube. If I wasn’t being distracted by a continuous stream of videos like this, I might have even been able to do it faster.

Here are some important things I’ve figured out about using the vacuum desoldering station, for anyone who has or decides to get one:

• • Clear out the tip of the gun and its filter spring frequently, and make sure the filter sponge stays wet. I clear out the filter spring by taking it out of the gun and melting the solder inside it with my soldering iron– you’ll figure it out.
    The tip of the gun part will clog frequently. The tool for cleaning the tip that came with the unit was not the best and I actually had to throw a few tips away because I couldn’t unclog them. Eventually I lost the tool and I got this one to replace it…

    

    …which I found on Ebay listed as “Tip Cleaner for Handheld Chinese Desoldering Iron,” and it is much, much better. Definitely worth getting for $1.50. I also get my replacement tips on Ebay, from SRA Soldering Products, and have a couple tips with different sized holes. I run this tool through the gun at least about every 10 minutes while I am using it.

    

  • If desoldering a large continuous area of solder (such as the solder surrounding a “snap-in tab” mechanically anchoring a large component), you can simultaneously heat it with your regular soldering iron and the desoldering station’s gun so that the whole area can melt, and stay melted, before sucking it.

    

  • Minimize as much as possible how much of the area of the desoldering gun’s tip actually presses against the PCB! If you push it flush to the PCB, you will most likely hear a crackle and the solder pad will come right off. It’s too much heat. If the angle of the component’s lead allows me, I will slide the gun’s hole over the lead and then tilt it slightly, so only the very edge of the gun’s tip is perched against the board, or with some particularly fragile boards, not allow it to touch the board at all.
  • Appropriate temperatures for different situations/synths: it took me a pretty long time to figure these out!

320-340 C – the lowest temperatures are reserved for the type of PCBs that have delicate, shiny silver traces adhered to just the top surface of a translucent plastic board. These are the worst! In ARPS, ElectroComps, EMS, very early Sequentials, a few other odd things. These were used as prototyping boards so you’ll find them in things that were made in smaller quantities– sometimes as the only board of that kind in the synth, if a manufacturer didn’t need many of a certain board. Oberheims look normal but are also delicate and require a low-ish temperature. Very old Moogs. Very small pads on Rolands.

340-365 C – for me, this is the normal range. 80s Rolands and Korgs (basically all Japanese synths post-1980 actually), Moogs, Sequentials… those common, enameled green boards with the exception of Oberheims. So basically all two-sided green boards from the 80s except Oberheims.

370+ C – reserved for only the most indestructible of boards, and wires just soldered to posts or lugs in components with no plastic parts. Milled copper boards seen on old combo organs and used as power supply boards of some other things.  And one more thing: lead-free boards.

• • And like I said at the beginning, if you don’t get it all on the first time, add more solder and start over. I could have avoided a lot of damage to boards over the years if I had known this in the past.

  Anyway, I hope this has been or can be helpful to some of you. I’m trying to use my blog to put the information out there that I wish I’d been able to read somewhere instead of figuring it all out “the hard way,” so I hope I can spare some of you some wasted time and lifted traces!

  P.S. tip for desoldering lead-free solder: add some lead solder to it first! Not sure this is a NASA-certified method but it works!