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desolder braid or suction pump

Discussion in 'Electronic Repair' started by Dave, Apr 15, 2007.

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  1. Dave

    Dave Guest

    which is better for desoldering IC's ?
     
  2. rebel

    rebel Guest

    depends on a lot of factors. Are these plated PTH or SMD IC's? Are you trying
    to recover the IC's and scrap the board, or vice versa?

    Rule#1: If you don't want to save the (leaded) chip, cut the legs first and
    remove them one-by-one. If SMD, I'd still be trying to minimise board damage by
    cutting leads if at all possible.

    My Rule#2: Desolder braid is largely ineffective on PTH unless the hole is
    laaaarge. I would (do) use a desoldering sucker.

    Just my 2c worth.
     
  3. Dave

    Dave Guest

    I have a board. I have 2 suspect chips. I have spares

    They are normal IC's

    it is an old vic 20

    I want to remove and maybe re-use if ok.

    If I put sockets on the board, can I put the ex soldered chip in the socket
    ? I mean, can I clean the legs enough to do this ?

    thanks
     
  4. Arfa Daily

    Arfa Daily Guest

    The legs of the ICs are usually tinned from the factory anyway, so the basic
    answer is yes. When you've got as much solder off as you can, finish off by
    scraping with a blunt curved scalpel blade. Use good quality turned pin
    sockets rather than leaf contact types.

    As others have said, a lot depends on the type of board as to whether a
    desolder pump or braid is better. If using braid, it is essential to use
    good quality, that is not old. And before the usual suspects start saying
    you can roll your own, yes you can, but it's a lot more convenient to just
    buy new. Whichever method you use, you should first flood the original
    joints with new solder, and let each one bubble a couple of seconds.

    You will struggle with either a hand desolder pump or braid, when you get to
    any pins connected to the power and ground planes. My advice would be to try
    both removal methods first, but once only. If you struggle to release any
    pins, I would not pursue it further, as board damage is sure to result. In
    that case, just cut the IC pins and remove them one at a time. There is a
    board that I work on regularly that has some ordinary DIL ICs which fail. I
    have a proper professional desoldering station that I use on them, and even
    that struggles sometimes. If it doesn't get the IC out first time, I just
    cut it out. Takes more time, but guarantees that the board will stay OK.

    Arfa
     
  5. Guest

    Mostly the sucker beats the braid by a long way. But there are a few
    folk that prefer braid.

    In that case its likely a multilayer board. Trouble with those is that
    sucking the solder out makes it impossible to melt what little's left.
    You may be better off not removing the solder at all, but melting and
    removing each pin, after cutting it from the IC. Then just use the
    sucker to clear the holes.
    Yes, but... you'll not get a flat smooth surface, so it may be
    difficult to get it into the socket, and very difficult to get it out
    again, but yes its poss, if you dont cook the IC or cut its legs off.
    With multilayer boards theres a good probability you'll end up doing
    one or both of those.


    NT
     
  6. Meat Plow

    Meat Plow Guest

    Used braid for many years but it depends on your skill factor.
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  7. James Sweet

    James Sweet Guest

    It depends. I have both on hand, usually I try the bulb first, it's
    attached to a desoldering iron, very useful tool so long as you keep a
    new tip on it. I haven't had much luck with the standalone bulbs.
     
  8. James Sweet

    James Sweet Guest

    If the braid is old, dip it in liquid flux. Makes a huge difference.
     
  9. I've had a solder sucker for twent years, and found that does work
    the best. On the other hand, at some point I did buy some desoldering
    braid, and when that runs out I would get some more to have around.

    I also bought a cheap desoldering iron, from Radio Shack, in the late
    eighties. It has the advantage that it's easier to use than an iron
    and a solder sucker. It was about ten dollars at the time, so I
    felt it was worth having around. But, the tip wasn't plated, so
    it didn't take long before it corroded and the unit wasn't particularly
    useful. The tip was removeable, but they didn't carry replacement
    sat the time. They later did, but I'd gotten out of the habit. I think
    except for the tip issue, the desoldering iron seemed the best choice.

    But again, some braid and a sucker are not really expensive, so one
    might want to keep both around.

    Michael
     

  10. Make sure it is ROSIN flux. Mild RMA is even better.


    --
    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
     
  11. Eeyore

    Eeyore Guest

    Both.

    Graham
     
  12. Thru-hole or surface mount?

    Are you trying to salvage chips for later re-use, or repair
    something?

    For thru-hole, I prefer a good power desoldering unit. I'm using
    the Pace ST-115 at both home and work. Excellent unit.

    For surface-mount, there are a number of rework stations available,
    none of which are particularly cheap. At the low end, you have the
    convection-heating (hot air) units, such as Hakko and Madell. At the
    higher end, you're still doing convection, but the units are better
    built (A.P.E., Pace, etc.)

    At the top of the line for surface mount are the infrared rework
    stations. I've never seen one sell for less than in the high four-figure
    area, and new ones have price tags that rival luxury cars or small
    homes.

    Now, with all that said: I do also use desolder braid. However, its
    main use with me is cleaning off surface-mount pads, or component holes,
    prior to replacing said component.

    Happy hunting.
     
  13. Dave

    Dave Guest

    thankyou for all your help.

    i dont want to spend much, so I shall struggle on....
     
  14. Franc Zabkar

    Franc Zabkar Guest

  15. James Sweet

    James Sweet Guest


    I never did have much luck with those things, the solder always seems to
    solidify by the time I get a good seal. That mechanism with a heated
    metal tip would probably work well.
     
  16. bz

    bz Guest

    Be sure and get some 63/37 solder. It is eutectic solder (the solder melts
    and freezes at a single temperature, the lowest possible for the elements
    involved.

    Many use 60/40 or even 50/50 solder. These both pass through a 'plastic'
    stage when melting and when freezing. Any disturbance of the joint during
    the plastic stage results in a 'cold solder joint'. Crystals of the higher
    melting element form.

    Note, now many countries require 'no lead' or 'low lead' solders. These
    tend to melt at much higher temperatures. For each pair (or trio) of
    elements, there is a ratio that gives a eutectic mixture.

    In any case, when desoldering, adding some 63/37 solder to the joint. It
    will help you 'disolve' the original, higher melting solder, and remove it.

    There are some controlled temperature irons combined with a vacuum pump
    into a desoldering station. They are not cheap but are a good investment if
    you are doing a lot of board repair.

    There are conductive ink 'pens' to allow repair of circuit board traces.

    For a more professional look, there are stick on solder pads and traces.
    Some of the board repair kits even include fiberglass making materials to
    repair the board itself and solder resist to repair the solder mask, along
    with dyes to color these so that the board looks 'as good as new' when you
    finish with it.

    Google for 'eutectic solder', 'desoldering station' and for 'pcb repair
    kit'


    --
    bz 73 de N5BZ k

    please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
    infinite set.

    remove ch100-5 to avoid spam trap
     
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