I used a spring plunger type desolderer for many many years and if I could still see I'v d always have one with me. Very good devices, but do have some spare nozzles handy and clean the innards quite often. the rubber bulb ones were pretty useless. Braid does not work well on non leaded solders and not that well either on the traditional kind as its based on it being able to kind of mop it up. It seemed like snake oil to me. Brian
Probably lead free solder. Braid doesn't work to well on it.
Through hole components is one case where low melt solder (ChipQuik or similar) could come in handy. The usual problem is that you have plated through holes, often with buried layers, and you need to remove a many-pin connector without disturbing them. You can't pick the pins off one at a time (a traditional through-hole desoldering technique) because a plug of solder remains in the hole. Hot air also doesn't help much since you have to heat a large area of board to its full depth, which tends to overcook the top side.
Would be interesting to know, since ChipQuik (Cerrolow 136, 20% Indium, melts at 58C) is frighteningly expensive.
Theo
The trick is to re-solder the joint first with leaded to make sure it is now clean, so the braid can make decent contact.
Generally, you'd only remove a through hole component because it is faulty. So carefully snip off all the 'legs'. They are much easier to remove from a delicate multi-layer board individually.
Or even 'low melt' solder (and possibly extra flux). I've used that to good effect on some multiple pin connectors (like laptop DC power jacks) so you can then heat all the pins at once and the socket falls out easily.
That sort of process really needs quite a good technique, good eyes and often quite a bit of patience, especially if you want to replace the component without doing any further damage to the PCB or surrounding components (as I'm sure you know) ;-)
Cheers, T i m
Roses metal melts at 100C or thereabouts. It contains lead as does Cerrolow 136.
Its the indium that is expensive!
Woods metal melts at 70C and is very cheap, but I wouldn't touch it. Lead may be bad, but cadmium is something else.
Much easier with a proper de-solder iron. Use a bit with a hole which fits over the pin. Once the solder has melted, waggle the iron around to move the pin while sucking.
Yup, as mentioned elsewhere, I wouldn't be without my suction desoldering station now (and used it yesterday in fact). [1]
Cheers, T i m
[1] It was one of those days where I knew I probably should have just stayed in bed. Motorbike needs MOT next week and it's not been run for a while so pulled the battery out and went to put it on charge on my brand new (but cheap) 5-15V, 0-15A bench PSU. I did what I never do and hooked it up backwards (for a second tops) and there was that horrible smell of burning electronics (and money). ;-(I left it a while then pulled it apart, not expecting to be able to do much and found a SMPSU on a PCB. I lifted the board and noticed the (6mm wide and flood soldered) power output track had burned through in one section. I soldered a 15A fuse across the break tacked it all together, tried it again and it still worked!
I then used my desoldering station to 'suck' all the extra solder off the entire length of the track (just like vacuum cleaning) and ran some 1.5 sq mm copper wire (2.5mm earth) from round the end wire, down the entire track and round the other end component and because the desoldering gun iron is pretty powerful (140w?), after first tacking the wire down in several places, used that to flood solder the wire back along the track. I'm now going to fit a fuse into the output line because although it's already short circuit protected, it's not c**t proof if someone connects a battery to the output back to front (FFS). ;-(
I fixed the PSU *then* went back to bed, before I hurt myself (again, I was leaking blood from my thumb all over the tools / PSU somehow) or damaged anything else.
Depends. Sometimes you want to salvage a connector or other component that you can't easily buy (because they aren't made, or because you'd pay squillions in shipping, or you need one /right now/).
Sometimes you need to remove a component that doesn't have accessible legs, and the 'mash it up with side cutters' approach risks damaging the board. Many connectors that mount flush to the board are like this.
For instance, I currently have a credit-card sized board that has about 100 pins of headers that I want to remove (to reduce the height). I'd guess it's at least 8 layer PTH (with blind vias). It's pretty unlikely that any kind of mechanical approach is going to work here: chewing up the plastic to get each pin separately will likely damage the board. That's why desoldering is a more attractive option, if it works.
Theo
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