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heat sink attaching

Discussion in 'Electronic Repair' started by David Lesher, Oct 11, 2013.

  1. David Lesher

    David Lesher Guest

    I need to add a heatsink to a small product. It has a flat exposed flush
    heatsink now; I'm extending with fins.

    But the attachment is an issue. Do the pads you put between a CPU & heatsink
    provide any stick? Or are the depending on external pressure to compress
    them? [I have no way to do that...]

    For the record, this is a Mobius camera.
  2. gregz

    gregz Guest

    What do you want to do, and why ?

    Temporary or permanent ?

    Pads don't usually have optimum heat transfer. Metal to metal contact is
    optimum, unless surfaces are really off.

    Does the camera instructions say, add heat sink ?

  3. Charlie+

    Charlie+ Guest

    Pads normally require mechanical pressure permanently.
    You can use epoxy resin as long as the layer is thin and you prepare the
    surfaces for mechanical key. Used this method on componants running
    too hot to last! Fast set epoxy is better because it never quite seems
    to set as rock solid as slow cure and thus shouldnt shatter under shock.
  4. Phil Allison

    Phil Allison Guest

    "David Lesher"

    ** Suggest you lightly sand the mating surfaces with fine emery paper and
    then smear with "super glue".

    Hold together tightly for several minutes.

    Should be reasonably strong.

    ..... Phil
  5. Phil Allison

    Phil Allison Guest

    ** The opposite is true.

    1. Pads vary enormously in their performance - the cheapest are silicone
    rubber and are shit awful at conducting heat.

    2. Nothing beats two smooth, mating metal surfaces with a smear of compound

    3. Next best is thin mica insulation (1 or 2 thou of an inch ) with a smear
    of compound each side.

    Even pressure is crucial to getting good thermal transfer, the usual bolt in
    the top part of a TO220 or TO3P metal tab is a horrible way.

    .... Phil
  6. David Lesher

    David Lesher Guest

    The camera has a reputation for running hot. In fairness, the
    original market was RC aircraft where forced air cooling is
    readily available. Other non-RC users have added heatsinks.

    I studied the thermal conductivity issue a few years ago; I was
    coupling sensors to copper pipes & comparing approaches. What
    I found was any of the pastes & conductive epoxies I found had
    thermal resistances so high, vice metal-to-metal, they looked
    useful only against air gaps. In other words, they help by not
    being air, but lapping is a far better solution.
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