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Soldering, time for hot air?

Discussion in 'Electronic Repair' started by Jeff, Dec 31, 2007.

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  1. Jeff

    Jeff Guest

    I just replaced a Cyrix surface mount 486 cpu this weekend with my
    conventional Edsyn temp controlled soldering station. I cut the old chip
    body off, cleaned the pads, and used the my own version of the "flood
    and wick off" the extra method. The results were good and it works fine
    but there must be a better way.

    I was looking on ebay and it looks like there are some affordable "Hot
    Air" soldering stations. I really don't want to drop a grand on one for
    hobby work but I would like to be able to do more of this type of thing.
    So, are the ones that you see new for $150.00 to $200.00 any good? Can
    you get parts and different tips for them, and should I stick with one
    brand over another?

    Here is a link to a couple pictures of the board with the CPU that I
    replaced.
    http://www.amiga.org/modules/myalbum/photo.php?lid=3657&cid=13
    http://www.amiga.org/modules/myalbum/photo.php?lid=3656&cid=13

    Thanks for any suggestions and Happy New Year to everyone here.

    Jeff
    (jeff at newsguy dot com)
     
  2. msg

    msg Guest

    <snip>

    I built my own; it works well and has adjustments for temp and airflow.
    Perhaps this is an alternative to a purchase. Please see
    http://www.cybertheque.org/homebrew/smt-rework-tool

    Regards,

    Michael
     
  3. Rich Webb

    Rich Webb Guest

    Web-Tronics has some affordable units that look like re-branded
    Xytronic. Howard Electronics has the real Xytronic units (also
    mostly affordable). I've purchased equipment from each and
    haven't had any issues.

    Hoods are often interchangeable but do check the dimensions,
    of course.

    You also may not need as many hoods as you imagine. There's a
    good tutorial on using hot air over at Sparkfun where they mostly
    use a single pipe hood. Don't miss the videos.

    Finally, also check out the ChipQuik system. If you don't do a
    lot of rework then it may be a better route. It really does work;
    I've used it myself on some 0.5mm TQFP packages and was able to
    reuse the part and the board (no clipping!).

    http://www.web-tronics.com/soldering-equipment---supplies.html
    http://www.howardelectronics.com/xytronic/products.html
    http://www.sparkfun.com/commerce/hdr.php?p=tutorials
    http://www.chipquik.com/
     
  4. I'm in the UK and bought one of these:-

    <http://cpc.farnell.com/jsp/Tools,+S...D-939A/89-3912/displayProduct.jsp?sku=SD01139>

    which I'm sure is available elsewhere. Remarkable value for money. I know
    of a repair shop where one is in heavy use and it seems to have survived
    for a couple of years.

    Only thing I dislike about it is it runs when you first power it up and
    scares the life out of you - if it's on a master circuit like in my
    workshop. I find it a decent addition - but not a replacement - to my
    conventional de-solder station.
     
  5. Rich Webb

    Rich Webb Guest

    Looks very similar to the Xytronic I have. Probably one factory
    makes 'm all and silkscreens on the various labels. ;-)

    Interesting picture on that site, though. They either got the
    tool hanger on upside down or that's another one of your "we
    drive on the *correct* side of the road in the UK" issues.

    Only kidding, of course. Happy New Year!
     
  6. whit3rd

    whit3rd Guest

    Good for you! That removal can't have been easy.

    There's a good removal solution that works without extra
    soldering hardware, called 'Chip-quik'; it's a very low
    melting point solder, you just clean, flux, add the special solder,
    then the whole chip lifts up at circa 100C (which is the melting point
    of the alloy).
    Of course, it needs to be cleaned up before re-soldering with real
    solder. The removed part doesn't need any leads clipped,
    though.
     
  7. mike

    mike Guest

    Depending on how much you need to do, you can do considerable soldering
    with a variable paint stripper gun. They're power controlled, so the
    temp varies with air flow, but you can still do a reasonable job with
    a homebrew head/baffle assembly and a thermometer.

    Another thing that works way better than I expected is a Portasol butane
    torch with the catalytic
    hot-air tip. Works great for small stuff. If you use the hot air
    or a hotplate to preheat the board, you can use the butane torch to
    quickly reach the melting point and do rather large stuff. The torch
    puts the heat in a small space right where you need it.
     
  8. Smitty Two

    Smitty Two Guest

    I've had good luck by adding flux, wicking all the solder I can from
    each connection, and then popping each leg off its pad with an x-acto
    knife. The tiny amount of solder bond that's left just breaks loose.
    Part is saved and re-usable, if it was good to begin with. (If I get a
    tough leg I reheat it while sliding the blade under it.)
     
  9. Yup - a bit like electric drills. Dozens of makes from one factory.
    So they have - never noticed it. ;-) Probably assembled by the art
    department. ;-)

    And to you and everyone.
     
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