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Thermal Epoxy

Discussion in 'Hobby Electronics' started by Big Matt, Jan 31, 2006.

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  1. Big Matt

    Big Matt Guest

    Does anyone know where I can purchase thermal epoxy? I have some small
    copper heatsinks that I want to attach to some transistors. Jaycar and
    DSE don't appear to have it, and a search for thermal epoxy on
    farnell.com also produced nothing. I could, of course, be searching for
    the wrong thing....

    Many thanks
     
  2. Mark Harriss

    Mark Harriss Guest


    I get great results from close fitting heatsink / transistor surfaces
    and superglue. It's possible to speed up drying by putting a few drops
    of water over the glued items to keep air away from the glue which then
    sets.
     
  3. Geoff C

    Geoff C Guest

    As far as I know, most epoxies are thermoplastic, which means they will
    soften with temperature. There are cyclo-allophatic thermosetting ones but
    probably harder to get. You can use a thermal acrylic designed for the job
    such as Loctite "Output". This works well for heatsinks. I think it is
    avaliable from RS and I seem to remember seeing it at Bunnings once.
     
  4. I assume superglue is a good thermal conductor???

    3m is probably the best bet. Although the OP gives no idea on
    quantity, 3m reps are usually very helpful. I have used a thermal
    epoxy from 3m for temperature compensation in conductivity sensors
    with very good results. Highly recommended.
     
  5. Mark Harriss

    Mark Harriss Guest


    I'm inclined to think it's not, but then even thermal grease is not
    a good conductor of heat compared to metals such as aluminium or
    copper and silver, the secret to using thermal grease is to use as
    little as possible to ensure the two have air free contact. When
    I use the superglue the heatsink gets fairly hot so I'm assuming
    there's a transfer of heat. Most conventional epoxy's go jelly soft
    with heating.
     
  6. Mark Harriss

    Mark Harriss Guest

    Ahh so that's how it works!.
     
  7. Poxy

    Poxy Guest

    Bicarb of soda will also accelerate superglue setting,.
     
  8. atec77

    atec77 Guest

    most hardware stores carry epoxy putty , its used as a filler and in air
    conditioning .
     
  9. As long as you dont want high mechanical strength, silicone RTV works
    better than epoxy. Conductivity is higher, and strength doesnt degrade
    with temperature. Make sure you use the neutral cure type, so you dont
    get corrosion from the acetic acid released from some other types of
    silicone.

    --
    Regards,

    Adrian Jansen adrianjansen at internode dot on dot net
    Design Engineer J & K Micro Systems
    Microcomputer solutions for industrial control
    Note reply address is invalid, convert address above to machine form.
     
  10. Mark Harriss

    Mark Harriss Guest

    As it supplies the OH- hydroxyl ions that water can supply, but
    more of it....thanks!.
     
  11. Mark Harriss

    Mark Harriss Guest

    Also some of the common RTV's like Loctite blue are good in high vacuum
    environments, but not super high vacuums as they don't outgas too much.
     
  12. I am not sure what they use in thermal epoxy, but it looks like it has
    aluminium in it and it stays rock solid at any temperature that a
    semiconductor will ever get to without catching on fire.
     
  13. Big Matt

    Big Matt Guest


    Thanks to everyone who replied. I have stumbled across a product called
    Arctic Silver Thermal Epoxy, which looks like it will do what I want.
    Bunnings didn't appear to have anything that was mentioned here, and RS
    want a hundred bucks for the loctite product, which is more than I spent
    on the circuitry. Normally I use screws and thermal grease to attach
    heatsinks, but in this case I packed everything too close together to
    make that possible.

    Thanks again
     
  14. crazy frog

    crazy frog Guest

    yes wes components
    www.wescomponents.com
    phone 02-97979866

    heatsink glue drys like hard rubber
    code number TSE3843W cost $38.50
     
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