Tips For Desoldering

[Richard_FM]

Does anyone have any tips on how to desolder components from a circuit board so a replacement can be installed? especially how to remove the solder cleanly.

[Wendymott]

I use 3 methods, all for different situations. Large IC's with plated through holes.. Hot air gun...care is needed for local adjacent components... If SMD they may disappear.
Items with large solder pads... Solder sucker....
Small items... desolder braid.

[SiriusHardware]

More context needed Richard, do you mean:

-How to remove the solder cleanly so that the component can be removed?
-How to remove the solder cleanly after the component is removed?

If you are removing a multi-pin component (ie, a chip) which you are certain is faulty then it is often better to snip each pin off near the body of the device and desolder and remove each pin individually with a pair of fine stainless steel tweezers.

I use an electrically assisted hollow-tip OKI/Metcal desoldering iron for most through-hole component removal jobs and I use the same tool to clear any blocked through-holes afterwards, but if you have only basic tools then the above approach is better than trying to keep all of the solder joints melted while you remove the device.

[Biggles]

I use a spring loaded pump action solder sucker which is cheap and cheerful but can be very effective if used with care. Beware, they can scatter little bits of solder all over the board which needs to be removed carefully. The plastic nozzles require periodic replacement too. Professional desolder stations are expensive. I rarely use de solder braid any more, but it can be effective. A good tip for desolder pumps is that if they don't clear all the solder from the joint with the first attempt. Leave the work to cool down (and the track glue to rebond) for ten minutes then add more solder to the joint to build it up, leave for ten minutes to cool, then have another go. Quite often this will clear the hole. Avoid overheating the PCB at all costs. Be patient. You can end up having lots of tea breaks at work, but you have a great excuse. Snipping each leg of a definitely faulty multipin component and removing them one at a time is good advice too.
Alan.

[G8UWM-MildMartin]

If you have £84 to spare, the soldering & desoldering version of this machine has earned its purchase price many times over ar Work:
https://cpc.farnell.com/duratool/d00...st=desoldering (the soldering iron on the combined version (https://cpc.farnell.com/duratool/d00...-eu/dp/SD01386) is not really worth the extra.)
For the previous 27 years, these:
https://uk.rs-online.com/web/p/desol...pumps/4794197/
have been better than its Weller competitor, and the quality isn't noticeably worse since AB moved its manufacture from UK to China (£10 in 1988, now £21) and will do a perfectly good job once you're used to them.
The tips for the Duratool machine are £1.19, compared with £3.86 for the simple sucker.
I have never got on well with desoldering braid: too many lifted pads and burnt fingers!
I could take a board in to Work to desolder for you, if that would help.

[mickm3for]

I find desolder braid works better if extra flux is used

[Diabolical Artificer]

"I could take a board in to Work to desolder for you" That's a kind offer.

I find solder braid needs lots of flux to work well, I've also used cut off's of copper cable and the inside sheath of co-ax.

For valve bases and big stuff that can take it I heat the joint and give it a sharp tap ont bench, covers the bench in spatter but not worried.

One aspect of de-soldering/soldering hardly ever mentioned is cleaning up the excess flux afterwards, I use meths or nail varnish remover but there's better stuff.

Andy.

[Radio1950]

For general PCB work with low value equipment, with just a few replacement components, braid is good.
For irreplaceable, or fragile high value PCB equipment, buy a vacuum desoldering station. Essential.
You wont regret either.
Look for an online training video on desoldering from an accredited provider, and watch and listen closely.
You wont regret that either.

[Station X]

In the case of IC's I cut through the leads close to the package using a Stanley knife with a new blade. This leaves plenty of pin to grip during desoldering. I know it's frowned upon, but I fit the new IC in a socket with turned pins. These have never given any trouble.

Also frowned upon, I have been known to heat solder and blow it away with a compressed air jet. It does scatter round what I call aerated solder, but this is easily brushed away.

SM component replacement I put out to someone else.

[TrevorG3VLF]

I have reshaped a short piece of central heating copper pipe which which has been made fit on my tapered soldering iron bit. I can remove one side of a 16 pin IC with this. I need to remember to be careful when removing it from the iron.

I have recently obtained a combined hollow soldering iron and manual sucker. This works well.

Desoldering braid needs to be uncorroded. Old braid is useless. I use coax braid with added flux.

[dominicbeesley]

For years I struggled with a variety of solder suckers, braid, side cutters etc. Last year I needed to do a batch of BBC Micro motherboards and treated myself to one of these:

https://cpc.farnell.com/duratool/d00...SABEgLhCPD_BwE

It's not of much use on valved stuff but for doing a lot of through-hole components its great and is non-destructive to the components which often I need to remove test and refit. The only niggle is that the gun tip and barrel need fettling after use as they tend to get blocked.

I also got a cheap Chinese solder station with a soldering iron and hot air rework gun for smd stuff - I fully expected it to be consigned to the bin after its first use but it is now my main soldering station! The hot air gun fan sounds like its about to stop working occasionally but after a shake comes back to life!

D

[paulsherwin]

Originally Posted by Station X

Also frowned upon, I have been known to heat solder and blow it away with a compressed air jet. It does scatter round what I call aerated solder, but this is easily brushed away.

On occasion I've blown melted solder away using a ballpoint pen case held in the mouth. You do have to be careful to remove the scattered solder of course.

[PsychMan]

This thread is well timed for me because my desoldering skills suck, unlike my crappy old solder pump

I may well invest in that desoldering station suggested. I usually manage ok with a solder pump and careful heating / prizing / bodging, but ended up lifting a track on a level fader on one of my mixers doing that. I aborted the replacement and resoldered the fader back until my skills can improve!

In general I can desolder stuff on valve gear just fine, but "many pinned" ICs and other bits on PCBs often result in some level of carnage

[PsychMan]

Originally Posted by paulsherwin

On occasion I've blown melted solder away using a ballpoint pen case held in the mouth. You do have to be careful to remove the scattered solder of course.

I like the sound of both of these methods, and its far cheaper than a £70 desolder station

[60 oldjohn]

Originally Posted by PsychMan

In general I can desolder stuff on valve gear just fine, but "many pinned" ICs and other bits on PCBs often result in some level of carnage

I once recommended cutting the pins on large surface mount chips then de-soldering the pins, and got shot down. what happens if the knife slips?


I now use one of the many low melting point alloys available "Quick Chip" is one, not cheap but depending on the chip you should not use much. It melts onto all the pins and remains liquid for maybe 30 seconds or more, allowing plenty of time to lift the chip (Tip) blue Tack stuck on the end of a screwdriver helps lift the part. I only use an ordinary soldering iron. I ordered my Quick Chip from Ebay it arrived not in a six inch length but in many quarter inch lengths it is very brittle but it works just a well. Use plenty of flux when cleaning the board. Watch a demonstration on You Tube.
John.

[G8HQP Dave]

I use a solder sucker. In an ideal world the solder will all have melted, the sucker will be perfectly seated on the board and then the air blast through the PCB component hole will push all the solder up into the sucker leaving just a tinned PCB track and tinned component lead with a tiny air gap between them. I have only managed this a few times! Generally it needs several attempts to get an approximation to this.

Once most of the solder has gone you can sometimes take advantage of the fact that solder can become brittle and break of it is flexed too much; so flex it too much, but be careful of damaging or lifting the track. Removing a faulty component is a bit easier than removing a good component because you will be less worried about damaging the component.

[Steve G4WCS]

I like the look of the duratool desoldering station.

About to embark on an Icom IC-251 recap so may invest

[Richard_FM]

Thanks for the advice, I'm planning to replace the capacitors in my Sony VCR that are causing trouble & wanted to do a neat job.

https://www.vintage-radio.net/forum/...d.php?t=156973

[ekjdm14]

Personally I've always managed well on through hole and point to point stuff with a cheap pump action solder sucker, they work really well as long as you keep it cleaned out & I also found lubricating the O-ring with a little Vaseline or coconut oil(!) improves efficiency.

There is something to be said for blowing away of solder in some cases though, I think the main thing to get safe and effective desoldering on through hole components though hasn't been mentioned yet, and that's the temperature and thermal mass of your chosen tip. I find that working hot & fast with as large a tip as I can work with has been key to not damaging traces so far. Get the solder molten, get it out of there & get the heat off before it's soaked too much into the board or component. For reference I run my iron (only calibrated by DMM thermocouple) at around 365c for desoldering through hole and 380 for point to point.

[kalee20]

One method not mentioned so far, for circuit boards with plated-through holes, after you have removed the component lead but want to clear the hole of solder ready to insert the replacement - hold the board 8" off the bench, heat the pad on the top surface with your iron, feed some fresh solder on to get flux on the job, then smartly bang the board downwards away from the iron onto the bench.

Molten solder is quite heavy. You will find that when the board hits the bench, the momentum of the molten solder is enough to carry it out of the hole and splat on the bench.