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Desoldering — Parallax Forums

Desoldering

UnknownUnknown
edited 2010-02-24 01:41 in General Discussion
Does anyone have any good tips on desoldering ICs?

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Comments

  • Peter KG6LSEPeter KG6LSE Posts: 1,383
    edited 2010-02-22 14:45
    I use one of these desoldering_tools.jpg
    but I removed the bulb and attached a a hose goin to a vac pump .

    Peter KG6LSE

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    "Carpe Ducktum" "seize the tape!!"
    peterthethinker.com/tesla/Venom/Venom.html
    Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway. —Tanenbaum, Andrew S.
    LOL
  • kwinnkwinn Posts: 8,697
    edited 2010-02-22 15:04
    Depends on what package they are in and whether or not you want to save/reuse the board.

    My preferred method is a hot air de-soldering station but they are somewhat expensive. I have also seen a "home brew" de-soldering station that used a small propane torch with guides to direct the heat to the leads and a small suction cup to grip the chip.

    For through hole parts:
    A soldering iron and solder sucker or solder wick to de-solder one pin at a time. Board can be reused.
    An iron with a tip to heat all the leads at once and a spring clip to pop out chip. Board can be reused.
    A soldering torch and spring clip. Board is toast.

    For smt:
    A soldering iron and solder sucker or solder wick to de-solder one pin at a time. Very difficult on small chips, almost impossible on chips with more than a few leads. Board can be reused.
    An iron with a tip to heat all the leads at once and a vacuum system to hold and pop out chip. Board can be reused.
    A soldering torch and vacuum system. Board is toast.
  • LeonLeon Posts: 7,620
    edited 2010-02-22 20:12
    For through-hole I use desolder braid. For SMT I use Chip Quik. I have got a hot-air rework station but haven't tried it yet.

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    Leon Heller
    Amateur radio callsign: G1HSM
  • Tracy AllenTracy Allen Posts: 6,666
    edited 2010-02-22 20:47
    You can purchase lo-melt solder that you apply over the pins of the IC, then keep it heated to around 150 degC for about 10 minutes. The low temperature solder alloys with and dissolves the normal solder, and you can lift it up with tweezers. Then vacuum up the residue. Can save the board, the chip or both. I think the Chip Quik that Leon mentioned is pretty much the same idea. The alloy is expensive, but a little goes a long way. For many things the solder braid or heat gun is better or faster.

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    Tracy Allen
    www.emesystems.com
  • Clock LoopClock Loop Posts: 2,069
    edited 2010-02-22 23:54
    Although its generally a bad idea because it flings hot solder all over the place, but if your in a pinch,
    heating up the solder and then quickly whacking the pcb on something, can get solder off pcbs pretty well.
    I have saved many ic's and pcbs because I knew about this last resort method.
    Also consider that this will most likely fling solder all over your pcb also, so you will need to inspect it when your done.

    Again, only do this if you have a protective shield to stand behind.
  • FlyingFishFingerFlyingFishFinger Posts: 461
    edited 2010-02-23 07:19
    If you have either good eyesight or a microscope and steady hands, the following has allowed me to reuse both the chips and the board: Wick off all the solder you can, then pry up each pin using a scalpel just enough for it to clear the pad. Impatience / hurrying will kill the chip though...

    Rafael

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    CalSol: UC Berkeley Solar Car
    http://calsol.berkeley.edu
    KJ6AWU
  • MicrocontrolledMicrocontrolled Posts: 2,461
    edited 2010-02-23 16:33
    Solder sucker works great unless the holes are plated through, then use a wick/braid.

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  • LeonLeon Posts: 7,620
    edited 2010-02-23 18:33
    FlyingFishFinger said...
    If you have either good eyesight or a microscope and steady hands, the following has allowed me to reuse both the chips and the board: Wick off all the solder you can, then pry up each pin using a scalpel just enough for it to clear the pad. Impatience / hurrying will kill the chip though...

    Rafael

    Lifting pads is the biggest danger. Before Chip Quik I used to thread a length of enameled copper wire under the leads and pull one end whilst heating the lead, then go onto the next one.

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    Leon Heller
    Amateur radio callsign: G1HSM
  • FlyingFishFingerFlyingFishFinger Posts: 461
    edited 2010-02-24 01:33
    True dat. Last time I did it, I was only able to remove and replace a QFN-48 twice before some pads got hard to work with (i.e hanging from their traces)

    Rafael

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    UC Berkeley '12 EECS
    CalSol: UC Berkeley Solar Car
    http://calsol.berkeley.edu
    KJ6AWU
  • Peter KG6LSEPeter KG6LSE Posts: 1,383
    edited 2010-02-24 01:41
    Clock Loop I too have used the "Heat , Whack and bang" method all the time to get parts of a board I dont want .
    its my method of choice when I am gutting a donor for parts .

    But like you said .. I full face shield is a must !! I whack the PCB against the inside of A 5 Gal bucket to aid in recovering the parts .

    Also when I desolder a RoHS Lead free PCB for " personal " use I use some kester 44 to lower the melting point of the lead free stuff

    kinda like the chip quick system with a twist ..
    Peter KG6LSE

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    "Carpe Ducktum" "seize the tape!!"
    peterthethinker.com/tesla/Venom/Venom.html
    Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway. —Tanenbaum, Andrew S.
    LOL

    Post Edited (Peter KG6LSE) : 2/24/2010 1:46:36 AM GMT
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