Using heat gun for desoldering questions

Discussion in 'General Electronics Chat' started by UnnamedUser159, Sep 27, 2016.

  1. UnnamedUser159

    Thread Starter Member

    May 3, 2016
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    Hi there.
    I have never used it for that.
    I have removed adhesive, heated heat shrink and video chips but never used it for desoldering.
    Now i have one board here - from car Renault. It`s ciu 21673814-9
    There are stuff that are connected to board with a lot of pins. I have tried to use desolder pump but a liitle solder stays.
    The question is how to be temperature in Celius to do the job but the board to stay healthy.
    I will make a photos if needed.

    thanks in advance
     
  2. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    If the pins are underneath the chip then solder iron will not work.
    If pins extend outward and are easily reached you can remove the chip by using a small pin or pick and bending each pin upward slightly as you heat the pad to melt the connection. (A wood toothpick is perfect because it will not cool off the pin when you touch it)
    Be careful if you are planning on reusing the chip. If not then less care is needed in bending the connection pins.
    To use hot air, be sure to mask off other areas with several layers of tape and use a long pair of suitable tweezers for lifting. It is tricky because you can destroy the chip if you apply to much heat or work to slowly.
    You will know when enough heat has been applied because the chip will lift off the pads. Keep the hot air moving around all 4 sides, don't stay in one spot to long. It is an art as much as a skill.
     
  3. atferrari

    AAC Fanatic!

    Jan 6, 2004
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    I made the experience of massive desoldering of components from 3 motherboards in one session using a heating gun. If temperature depends of two positions of the switch, you cannot say you are controlling much.

    I put them upside down on a cooking pot. Parts and components fell down mostly by themselves.

    I cannot avoid the feeling I was almost cooking them.
     
  4. MrAl

    Well-Known Member

    Jun 17, 2014
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    Hi,

    If you dont care about the chips you can cut the pins and remove the IC, then remove the pins carefully. That saves the board not the chips.
     
    atferrari likes this.
  5. MrSoftware

    Active Member

    Oct 29, 2013
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  6. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    I have desoldered with a heat gun. I grabbed the component with a pair of pliers and lifted the board slightly off of a heat-resistant surface (with the pliers). Then applied heat with the other hand. The board soon falls to the surface.
     
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  7. atferrari

    AAC Fanatic!

    Jan 6, 2004
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    I received a short period of training on reworking with hot air tools. It looked very appealing until I had to do it myself. Unless using a very focused nozzle, the risk of heating (cooking) components nearby drove me very nervous.

    BTW, nothing like having some practice on discarded boards whether for desoldering or soldering.
     
  8. MrSoftware

    Active Member

    Oct 29, 2013
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  9. MrAl

    Well-Known Member

    Jun 17, 2014
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    Hi,

    Yeah i noticed that too when i went to remove a few components on a couple boards. I was lucky in one case there was nothing closer than about 1/2 inch. In other cases though the chip spread is extremely unfavorable. Trying to remove the main chip, there are numerous tiny resistors and capacitors and whatnot right next to the chip. And i mean really small size SMD, smallest i have ever seen. If one came loose by accident i probably would not be able to get it back into place correctly. This leads me to be very careful with the board and if something does go wrong with the chip, it's too bad, i'll have to buy another board.

    They also make heat directors for various size chips where the hot air is directed on the pins only. I dont have any of those though, and apparently you have to have a separate size for every chip size you intend to desolder/solder.

    I almost forgot about ChipQuik as MrSoftware suggested, but never tried it myself.
     
  10. UnnamedUser159

    Thread Starter Member

    May 3, 2016
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  11. UnnamedUser159

    Thread Starter Member

    May 3, 2016
    130
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    Anybody ?
     
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