# How strong is Arctic Alumina and Arctic Silver - Epoxies?



## lightime (Aug 13, 2009)

I want to use Artic Silver or Artic Alumina expoxies to glue some LED stars to heatsinks inside some lamps including a few flashlights. How strong are these epoxies really? I have heard they are very strong but I have never used them before. Can they be used without any sort of mechanical attachment even if the lights will get banged up regularly?

I guess while I'm asking, are these products the best to attached LED stars to heatsinks or is there something better you guys are using?

Thanks for any feedback!


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## wquiles (Aug 13, 2009)

*Re: How strong is Artic Alumina and Artic Silver - Epoxies?*

Here in the forums we have been using Arctic Alumina Thermal Adhesive (two-part Epoxy) for several years now, to glue both the bare emiters and the stars to heatsinks, and it works extremely well.

I buy my Arctic Alumina Thermal Adhesive (two-part Epoxy) from forum member PhotonFanatic:
http://www.photonfanatic.com/ComponentsFS.html

Will


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## lightime (Aug 13, 2009)

*Re: How strong is Artic Alumina and Artic Silver - Epoxies?*

wquiles, thanks for the reply...much appreciated. I thought Arctic Silver epoxy was "better" than Arctic Alumina epoxy? Which one is stonger and which one conducts heat better? I am confused. :duh2:


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## 65535 (Aug 13, 2009)

*Re: How strong is Artic Alumina and Artic Silver - Epoxies?*

I think Arctic Silver epoxy has a higher thermal conductivity rating, the fact that it can be capacitive, and slightly conductive, means that where insulation is absolutely required and preferred that Arctic Alumina would be a better choice.

Realistically I don't think it absolutely matters, or that you would even be able to measure a difference. The Silver looks pretty cool imo.


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## PhotonFanatic (Aug 13, 2009)

You would only have to worry about Arctic Silver Thermal Adhesive's electrical conductivity if you were near some electrical traces.



> Negligible electrical conductivity:
> Arctic Silver Thermal Adhesive was formulated to conduct heat, not electricity.
> NOTE: Even though Arctic Silver Thermal Adhesive is specifically engineered for high electrical resistance, it should be keep away from electrical traces, pins, and leads. The cured adhesive is slightly capacitive and could potentially cause
> problems if it bridged two close-proximity electrical paths.


As for strength--either one will be perfectly fine--if you were to break that bond, most likely you would have something a lot more serious to worry about.


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## lolzertank (Aug 13, 2009)

IIRC, there was a reviewer who stuck a bolt onto a computer case with the epoxy and calculated the strength to be about 65 lb/sq in. That would be one heck of a bump to a flashlight.


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## Linger (Aug 13, 2009)

**posted in error**


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## lightime (Aug 13, 2009)

Thanks for all the replies. I am not so worried about a single hard bump or drop breaking it loose but more concerned say alot of bumps and drops over several years. 

Some of my flashlights are carried in my boat and are literally "bouncing" around ALL the time inside hard fiberglass compartments or tool boxes. Correct me if I'm wrong but compared to most other epoxies isn't 65psi pretty weak (again in comparison to other straight epoxies)?

What about potentially mixing up my own batch of epoxy plus aluminum powder or ???? to make something stronger? Or do you guys think I will be fine?


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## wquiles (Aug 13, 2009)

It will work fine, even in the application you state (lots of bumps), but you can make a stronger setup by using standard two-part clear epoxy on the sides of the emiter/start once the Thermal Epoxy has dried. That is what I do on my diving-rated builds.


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## 65535 (Aug 13, 2009)

It will be fine, figure the SA of the die will result in around 3lbs of static force to remove the led. I think it would be much higher in real situations. At any rate. 3lbs on the slug of the LED would be catastrophic to it. More than enough holding. If the led weighs only an ounce or less (likely far less) the amount of force (measured in G's) would be many many hundreds. I don't forsee a way to remove the led without damaging it.


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## Justin Case (Aug 13, 2009)

wquiles said:


> It will work fine, even in the application you state (lots of bumps), but you can make a stronger setup by using standard two-part clear epoxy on the sides of the emiter/start once the Thermal Epoxy has dried. That is what I do on my diving-rated builds.



That's what I do on my AW LED Turbo Tower builds that go into weaponlights. I figure that the added epoxy will help against shear. I'm not so worried against tensile forces. I also roughen the substrate surface to enhance the epoxy's grip.

If you Google epoxy adhesion to metals, you'll find that the adhesive strength depends on the metal.


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