PCB Desolder

I wish to remove components on a PCB.
Would like suggestions on best method and desoldering tool.

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Hi Les
A very broad question.
There are a lot of options and tools. Probably the most basic would be a soldering iron and small hand held plastic or metal vacuum pump. Several solder tool specialists like Weller, Hakko etc market dedicated de-soldering stations. A popular method is “Solder Wick” which is clean shiny copper braid with a resin flux impregnated. As the name suggests the “wick” is placed over the joint and heated with a soldering iron, the solder “wicks” into the braid and is effectively removed from the joint. Another method suggested by Marconi which is particularly effective for conformal coated boards involves a tooth brush or other stiff bristle brush and a bit of clean automotive grease. A bit of grease is applied to the brush and the joint heatted with an iron, The solder is then brushed out of the joint and the grease keeps the job clean and causes the solder to form little beads which can be brushed off the board without sticking to anything else. For some applications a hot air method is best.

Each different different circumstance requires a different approach. I don’t think anyone can give a definitive opinion as to which method will suit all occasions. A particularly difficult situation arises when you have plated through holes which are small and the component is too neat a fit. This does not allow enough room to remove the solder. Often the most expedient (and economical in the long run) way is to cut the legs of the component and remove them with iron and small pliers then remove the solder from the hole. This may seem a bit drastic but mostly the low cost of replacement components easily offsets the otherwise struggle to remove without damage.

In all situations care has to be taken not to overheat the board as the track will lift. Particularly on cheaper boards where track adhesion may not be up to scratch. Heat sinking effect of larger leads can affect this also.

Practise on some old redundant boards will also help.
Cheers Bob

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Thank you Robert,

I think you have outlined that which ever method is used it is not an easy task and caution is necessary.

Regards,

Les.

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Hi Les
Yes not easy for the inexperienced BUT experience starts somewhere and you cannot get it by reading alone. It is not that difficult either. Get hold of some redundant boards and have a go. You will then be able to think about it and decide which method is best for what job. Unfortunately the hobbyist usually has a limited number of options available but soon learns to improvise. The trick about cutting the component legs (particularly with ICs) and removing the solder from the empty hole has merits to get over a difficult situation but you have to have a new component to replace it with.
Keep trying and have a go.
Cheers Bob

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Hey Les and Bob,

Interesting question, I’d argue that it depends on what you’re removing. By the way, a trick that you’ll likely find very useful is to add some new fresh solder to the joint just before you try to remove it. Sometimes older boards or boards that have been in harsh conditions tend to be quite difficult to get the solder flowing again with heat alone, there’s some great tips on chemtronics that you may be interested in too.

https://www.chemtronics.com/12-easy-tips-to-improve-your-pcb-desoldering-process-today.

Solder wick is likely the best way to go here, you’re usually at less risk of damaging the components, it’s fairly cheap, and the end result is usually much cleaner rather than using a pump (also known as a solder-sucker).

Depending on how often you’ll be desoldering, some Tafe’s, workshops and Universities use tools designed specifically for desoldering. This is essentially a vacuum pump built into a soldering iron and makes it much faster to remove solder joints, although personally, I’d say it’s only a luxury if you’re not desoldering too often as it is quite pricy by comparison to your other options :grinning_face_with_smiling_eyes:

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Hi Bob,

I don’t think experience is an issue as I did 43 yrs as a tech. I am just probing to see if any new procedures have evolved.
I have soldering station, solder sucker, braid and have also ordered a vacuum op desoldering unit so if I get an unsatisfactory results it won’t be because of lack of equipt.
Now the message seems to be cut the board out for best results!

Regards,

Les.

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Hi Les
Sorry about that. Your experience is not apparent in your initial post nor your access to equipment and is completely unknown to people just trying to help.

I had done a similar period starting in 1964 but I haven’t worked full time for a number of years. As far as de soldering goes I haven’t really kept up but I don’t think things have changed much except for more surface mount and smaller size. Indeed I think with some components these days there is a very real risk of the component disappearing up the sucker tube.

While back at base in the factory we had the happy situation where if we had a really difficult problem re component removal we could pass it to the production or rework girls who had all the latest at their disposal. They even had a procedure for repairing damaged or lifted tracks. Like new. You wouldn’t know unless you saw it. They were very good at that sort of thing.
Cheers Bob

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Hey Les,

I would be curious to see if a reflow plate would get hot enough to melt all of the different types of solder as well.
I know they’re good for the initial reflow, but wonder if any additives evaporate off in that process (there are some shoddy videos on YouTube).

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Hi Liam,

I agree there is some misleading info out in u-tube land . There is also some good info given in and on Soldering labs with the capability of working with microdots! Some good points are made on the chemtronics site that make sense to me.

Regards,

Les.

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Hi Les,

Just weighing in that apparently solder suckers are best for through-hole components, while braids work well for SMD components.

I can’t say I’ve done much of either, however, so Liam and Robert’s expertise here is great to see.
-James

Hey James,

Deeefinitely not an expert here ahaha, other than fixing up mistakes on perf-board.
Adafruits ‘Collins lab notes’ are amazing to pick up lil skills (the gold IC’s look AMAZING!!)

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