Unsoldering components from things bought at a store

Discussion in 'The Projects Forum' started by jaygatsby, Nov 24, 2011.

  1. jaygatsby

    Thread Starter New Member

    Nov 23, 2011
    I tried to unsolder some components from a cell phone charger so that I could use them in future circuits of my own. I found them to be very difficult to unsolder, even with my iron at its highest heat level, and trying to unsolder them also created some smoke that bothered my eyes. Do commercial solder jobs use higher temperature solder?
  2. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    If it is newer, it's most likely a lead-free solder that melts 100 degrees F hotter.

    Always tin your iron so there is "wet" contact with the solder to be removed. If you can't remove the component after the first 5 seconds, let it completely cool off, otherwise you may be damaging the component (most all are rated 260 deg C for 5 seconds).

    Removing from double sided boards with plated through holes takes a bit more practice/skill, preferably a solder sucker or hot air pencil.

    SMD components are easy if you have a temp controlled heat gun. Put on an oven mitt, heat entire board, tap on workbench, collect parts. :D

    Be sure you don't exceed temp limits and time is all, otherwise you risk debonding the bonding wires that connect the outer pins to the inner die.
    elec_mech and jaygatsby like this.
  3. Adjuster

    Well-Known Member

    Dec 26, 2010
    Some may well use higher melting point solder, especially since a lot of the lead-free formulations are used nowadays. These typically have higher melting points than the tin/lead solders used previously. Sometimes meltiing a bit of ordinary solder into the joint and then wicking it away might help.

    De-soldering is in any case a bit of an art. A second iron can be handy, as can an assistant, unless you happen to be blessed with a spare arm or two! Seriously though, you may do better if you get hold of some de-soldering braid and one of those pump sucker gadgets - the latter can be a bit brutal though.

    Beyond that, you need to practice, but be careful not to hurt yourself. Note that it is a really good idea to invest in some fume extraction, at the very least some kind of fan so that any smoke is drawn away from your face. Goggles or other eye protection is also advisable, even more so than for normal soldering. If you are struggling to get a part off, it is all the more likely that something may move abruptly and send out bits of molten solder. The last thing you want is any of that in your eyes.
  4. Yako

    New Member

    Nov 24, 2011
    Double-sided through hole plated can take some time.

    I usually found that I had to apply new solder to each pin prior to using a gun to remove them. Trick with the gun is to wiggle it around the pin until all of the solder has melted, then all you have to do is pull the trigger.

    SDMs? I don't bother.

    Always make dead certain before you pull the trigger.

    I don't like these new Hakko guns. Plastic cylinder? Their 30-year-old classic design leaves the new models for dead.

    I bought mine from WES components back in the 90's, real workhorse. Day in day out PCB repairs (providing that you look after it: clean the cartridge when it is near full) I see some guys stuff them too lazy to clean the glass cylinder out and replace the filters. Then the pump fails. This is what I get for letting other people use my tools I guess. No respect. Not cheap either -- 2K at the time.
    Last edited by a moderator: Nov 24, 2011
  5. jaygatsby

    Thread Starter New Member

    Nov 23, 2011
    Thanks all
  6. bountyhunter

    Well-Known Member

    Sep 7, 2009
    Maybe lead free solder, but most surface mount boards require two soldering irons (one on each end of the component). For multi pin IC's, you need a special desoldering tool.
  7. sheldons

    Active Member

    Oct 26, 2011
    there are specialist tools available for smd removal-but you need to remember to be quick with your soldering iron or you damage the smd ... desolder braid is very useful here as you can quickly remove solder from a joint with practice before damage to the device occurs....also some smd ics are actually glued to the pcb as well as soldered.
  8. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    That's the first thing we used to teach the apprentices re how to desolder parts. Put lots of fresh solder (which also has flux) on the pins, it helps old or dirty solder to reflow and also the extra thermal mass of extra solder keeps the pads and pins hotter longer making it easier to pull the parts out.

    Many 3-legged parts I add enough solder to join all three legs, and then just pull the whole part out in one go with my fingers as all three pads are melted. The speed a good technician can pull parts from a board is pretty scary. ;)

    I refined a technique for desoldering DIL ICs, where you add lots of extra solder and join the pins in pairs (with the excess solder). Then my desolder pump has a squished oval nozzle that just fits 2 pins, so the increased solder bulk fills the nozzle better and gives more complete solder extraction due to the vacuum and also due to the increased temp as the bulk of 2 joined pads stays hot longer. It also requires only half the number of sucks/cleans from the pump. :)

    Yako- I have an older solder sucker gun here (glass tube). I have never used it much, and not at all in the last 8 years. Are you interested in purchasing? I will sell cheap.