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hot air

Discussion in 'Electronic Equipment' started by Walter Harley, Apr 24, 2005.

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  1. Occasionally folks here ask about approaches to SMT soldering on a
    hobby/prototype basis. The answer often seems to be "it works fine to do it
    with a fine-point soldering iron."

    Desoldering, though, is a little trickier. Even with solder wick, it is
    very hard to remove enough solder to actually detach a component, especially
    if you want the component to survive being detached (often not necessary).
    With SO chips it is possible to go one lead at a time and bend it up with
    tweezers, but it's a slow approach.

    Hot air rework stations are reputed to be a useful tool, but they're
    generally pretty expensive, for a small shop, so I've been very hesitant to
    plunge in. I finally did, and wanted to report my initial results.

    I bought a fairly cheap Chinese hot air station, an Atten 850D, from
    "Acifica", who sell on eBay and Vendio. The transaction (through Vendio)
    went very well: I got very quick responses to emailed questions, and they
    have a physical address and a phone number (I tend to distrust eBay entities
    who don't). I got email feedback every step of the way (order received
    confirmation, shipping confirmation, tracking number), and they shipped the
    next business day. The unit was very well packed. Total price was $268
    including shipping, for a digitally-controlled hot air rework station and 8
    nozzles. (It's possible to find cheaper hot air stations, but you can
    easily pay >$30 each for nozzles.)

    Upon receiving the unit I put it right to work, replacing an SOIC-16 chip on
    a moderately dense board. I was impressed at how easily it went: this is
    definitely the best way to unsolder SMT stuff I've found. Practically
    instant, with no ill consequences to anything else on the board, and the
    removed chip is intact and unblemished.

    The Atten 850D seems to be of adequate quality. The manual is pointless - a
    photocopied page or two of badly translated Chinese - but the unit itself
    quickly comes to temperature and seems to regulate well, has good control
    over airflow and temperature, and feels pretty solid. Nozzles attach easily
    and they seem to have provided a useful assortment; they're Hakko compatible
    in case replacement is needed.

    Hope this helps any other small shops considering similar issues.

    Disclaimer: I have no association with any of the mentioned entities except
    as a satisfied customer.
  2. Russ

    Russ Guest

    It seems there are number of 850D models by different company Yoyue, Madel,
    Atten, and a few others. They have a lot of different models and it is hard
    to figure out what the differences are when it might come to regrets. They
    have one setup that has a pre heater underneath and a stand and hot air on
    top for around $800.00+With over 30 different models of nozzles for extra$.
    I have a friend who works for a company called Sikama?? They sell hot plate
    ovens with a take the board through different levels of heat and cooling and
    adds gas. But that is besides the point. We took one of their basic Hot
    Plates. Heated it up to 220 and took a piece of aluminum or steal that was
    the same size of the chip I wanted to remove Then on a single sided board
    with a square SMD chip we brushed flux all over the pins of the chip and put
    the metal square on the Hot Plate and then held the board over the square
    underneath the chip. So the chip was face up. And the Square aluminum was a
    conductor of the heat from the hot plate. We held the board against the
    metal square for about 45 seconds and then the chip popped right off. There
    was no scorching and no damage to the board or chip as far as I could tell.
    I am going to buy a used hot plate an experiment some more but if this works
    effectively. Think of the cost savings, no nozzles, no complicated setups.
    Just little squares cut to the size of the chip you want to remove and a hot
    plate. I may be wrong. but if you have a hot plate give it a try on a board
    you don't use. My next step to try and solder it back on. Don't knock it
    until you try it. I worked great on about 5 of the different size SMD chips
    on the board.
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