heat conductive epoxy ??

gregatron

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Hey guys,
Late last night I was swapping some of my Vs. boards out and inadvertently knocked off the heat sync on the 2C03 on one of the boards. It looks as if it wasn't really adhered all that well in the first place. Does anyone know what I can use to re adhere it? What have you guys used in the past? I know this can not be an isolated event, I mean I'm clumsy sometimes but I really didn't knock it that hard. I was thinking JB weld but I'm not sure it's heat conductive. I may have to try to find something here at work thats used for that.
 
I use epoxy with west system aluminum powder mixed in.
You can also use arctic silver thermal epoxy but its kinda expensive.
 
I use epoxy with west system aluminum powder mixed in.
You can also use arctic silver thermal epoxy but its kinda expensive.
Is it really aluminum? Or is it alumina (aluminum oxide)? If it's aluminum be careful because it will conduct electricity. When I used to design ignition boxes for race cars, we used epoxy filled with alumina to pot the boards into the metal cases. It conducts heat very well, but is an electrical insulator. We did it for heat sinking, but mostly to make the boards vibration proof.

Although I think it's hard to have pure aluminum powder. It it came into contact with oxygen it would rust instantly, forming an alumina coating. That's pretty thin though. I don't know what the breakdown voltage would be. Mmmm.....nerdy rambling.....I'm tired.
 
Is it really aluminum? Or is it alumina (aluminum oxide)? If it's aluminum be careful because it will conduct electricity. When I used to design ignition boxes for race cars, we used epoxy filled with alumina to pot the boards into the metal cases. It conducts heat very well, but is an electrical insulator. We did it for heat sinking, but mostly to make the boards vibration proof.

Although I think it's hard to have pure aluminum powder. It it came into contact with oxygen it would rust instantly, forming an alumina coating. That's pretty thin though. I don't know what the breakdown voltage would be. Mmmm.....nerdy rambling.....I'm tired.

Its aluminum and its not an issue if you are just using it to hold on heat sinks. I wouldnt use it as potting material. Also... aluminum doesnt rust, it corrodes. Aluminum corrosion acts as an insulator. Anodizing aluminum is actually a dense layer of corrosion.
*end* usless information */end*

I posted what I did because I know it works and have used it hundreds of times. Use it like you would thermal grease, just a thin layer. If its running down the chip on the ic legs then you used way too much.
 
Yeah, ok. Corrosion is a process. Rust is the result. But most people think only of iron when you say "rust". I was being lazy. And I will probably continue. But just this once...when aluminum is exposed to oxygen it corrodes to form a very thin passivation layer of aluminum oxide. </CYA>

You are correct Riptor. I can't tell you how many trashpiles I've seen with chips that overheated because of thermal compound that was applied with a trowel. "It's still not cooling right. Put more grease on it. The best was the silver impregnated lump that managed to short a power supply. Burned the power traces on not one but several motherboards. The guy couldn't figure out what happened.

To emphasize what Riptor says use *A THIN LAYER* of thermal grease/glue. Whatever type it is. And I agree that it would be fine if you keep it where it's supposed to be.
 
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