Thermal Epoxy

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.

The transistors don't have a bolt hole for mounting on a heatsink ?

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Big Matt wrote in news:npzDf.407746$Es3.8517 @fe03.news.easynews.com:

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.

I assume superglue is a good thermal conductor???

It's actually moisture that causes superglue to set, and yeah, water works great.

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.

Ahh so that's how it works!.

Bicarb of soda will also accelerate superglue setting,.

most hardware stores carry epoxy putty , its used as a filler and in air conditioning .

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.

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

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.

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.

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

yes wes components

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