SMD soldering with hot air gun

Discussion in 'General Electronics Chat' started by dmta, Jul 10, 2013.

  1. dmta

    Thread Starter Member

    Mar 24, 2013
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    Hi all,

    I saw a lot of you-tube videos on soldering SMDs with the use of a hot air gun and solder paste. But all of those boards had solder mask on them which aided the proper flow of solder. But is it possible to do this without the solder mask? (my first thought is that it can't be done)

    The main reason I'm asking this is because I have this DRV8432 HSSOP package to be soldered.

    Regards
     
  2. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    Yes its 100% "possible" without a soldermask.
    possible doesn't mean easy though.. But its doable for sure.
     
  3. ian field

    Distinguished Member

    Oct 27, 2012
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    Possibly a better method is a modified tabletop toaster-oven, you need a thermocouple - interface & micro as the temperature steps have to be pretty precise. Possibly; both Circuit Cellar and Nuts & Volts have published projects - I think Elektor magazine did the project as a series of articles, and can supply a kit.

    Some types of solder paste will "bead" onto the solder pads if you don't lay it on too thick.
     
  4. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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    How would you keep the parts from blowing off the PCB?
     
  5. t06afre

    AAC Fanatic!

    May 11, 2009
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    It is not a problem. After some trail and error you will learn it. HOWEVER this technique require that the component is heated in a way that the solder are melted at the same time. Then the surface tension will adjust the component into a nice fit. Even on board that do not have solder stop layer. This component may doable to solder using the hot air method. But it will not be a beginner project. And visual inspection after the solder process will be needed
    EDIT: Proper purpose solder equipment will also be needed. You can not do this with a common heat gun. unless you like your component to behave like confetti on a windy day:D
     
  6. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    Most if not all hot air guns have an adjustable blower/fan speed to prevent this.
    And like t06afre said the surface tension of molten solder literally pulls the part into place.
     
  7. ian field

    Distinguished Member

    Oct 27, 2012
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    Once I constructed a wonderful contraption out of an old fridge compressor - part of the thin copper pipe was coiled and mounted with a gas burner, a carburettor jet brazed to the end of the pipe produced a fine jet of very hot air.

    This was for harvesting SMD parts off scrap boards.

    Simply place a cardboard box downrange to catch the SMD parts blasted clear.
     
    debe likes this.
  8. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    I once reflowed a SMD PCB on my kitchen stove top. I used a piece of metal to keep the board off my (ceramic top) stove to keep the stove safe.

    I gave up trying to set the temp with a thermocouple, so I just raised the temp some and waited till the solder just flowed.
     
  9. Metalmann

    Active Member

    Dec 8, 2012
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    I like that idea with the ceramic stovetop. I may try some using a plate of 1/4" thick sheet metal on my gas stove burner.
    Right now, I've been trying to use my soldering station heat gun, but do not have the technique down yet.:(;)
     
  10. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    cheap hotplates are perfect for reflow in a pinch.
     
  11. dmta

    Thread Starter Member

    Mar 24, 2013
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    Thank you ALL for replying.

    I wanted to ask this question before I ordered the part from TI free samples, so now I've ordered it.

    Best regards
     
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