# Make your Own Thermal Epoxy??



## mds82 (Nov 27, 2007)

I will be needing to glue a bunch of parts together, 100+ units 1 inch square, and dont want to spend a TON of money on Arctic silver thermal epoxy.

How much area does the arctic silver thermal epoxy cover?

If not, is it safe to mix thermal grease + 5 minute epoxy and get the same results?? something like this ? http://www.overclockers.com/tips683/


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## Mr_Light (Nov 27, 2007)

I highly recommend this which I have used to Glue dozens of Stars into many modded lights.

FUJIK Silicone Thermal Glue (50ml Grease-Like) $7.81 
http://www.dealextreme.com/details.dx/sku.4579


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## McGizmo (Nov 27, 2007)

You have many solutions to choose from. I think I would go with a large set of the Arctic slow cure ceramic epoxy because it has great pot time and provides excellent thermal adhesion after cure.

If I were going to make my own, I think I would get a good and hard setting two part epoxy and then thicken it considerably with some aluminum oxide powder.

I think you need to access how critical and demanding the thermal bond is going to be and let that dictate the level of attention you give the bond.


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## mds82 (Nov 27, 2007)

Mr_Light said:


> I highly recommend this which I have used to Glue dozens of Stars into many modded lights.
> 
> FUJIK Silicone Thermal Glue (50ml Grease-Like) $7.81
> http://www.dealextreme.com/details.dx/sku.4579



does this stuff actually dry, and does it dry hard


In the past i have always used JB Weld to hold the parts together because the strength is great on that stuff, however its thermal conductivity isnt that good afterall. 
What other options are out there?


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## Essexman (Nov 28, 2007)

At work we attach thermocouples to electrical devices to measure working temps. Quick set two part epoxy mixed with Zinc oxide powder in a 50/50 mix is used. I 've used it for a few mods too, appears to works well.


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## Mr_Light (Nov 28, 2007)

Think of this stuff like Thermal GE Silicone Seal. It's rubbery when dry. If you are looking for something rigid this is not it.


mds82 said:


> does this stuff actually dry, and does it dry hard
> 
> 
> In the past i have always used JB Weld to hold the parts together because the strength is great on that stuff, however its thermal conductivity isnt that good afterall.
> What other options are out there?


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## mds82 (Nov 28, 2007)

Essexman said:


> At work we attach thermocouples to electrical devices to measure working temps. Quick set two part epoxy mixed with Zinc oxide powder in a 50/50 mix is used. I 've used it for a few mods too, appears to works well.



OK. i'll have to give this a try. Thanks for the info!


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## laserblue (Nov 28, 2007)

in our country thermal epoxy is way way expensive


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## VidPro (Nov 29, 2007)

i mix copper dust into , well about anything to see if i can concoct something, even into Arctic Ailver.
also have a LB of aluminum oxide dust, but i only used it once, because conductivity was of issue.

everytime i add these Dusts to the normal stuff it changes the properties quite a bit. it can turn them into playdough fast.
With the arctic silver, it seems to make it harder, then i realised (and somone else mentioned) the expansion and contraction of dissimilar metals, and temperature changes, the "flexibility" of the AS was probably very usefull, the dusts added to it soak up the oils (or something) and makes it more "brittle".

JB weld and copper dust worked interestingly too, i dont have thermal specs, but i used it when heat transfer speed is not a huge requirement. same thing happens depending on the dust added, its just like adding flour to bread, it keeps getting thicker, quantity has to be controlled, so metal per epoxy cant get too high.
Lots of my applications so much direct metal to metal contact existed with the epoxy only filling the gaps, so its hard to tell the effect. but JB slow epoxy is many many times stronger and better than the clear junk. its also a VERY slow cure time, providing a much longer working time.

i think the most important tip would be, is there going to be expansion and contraction that over time will damage bonding? because time takes all good ideas and ruins them  ok, ok, so they were bad ideas  but even AS gets harder over time.

I have seen thin clear glues under led star items come loose in a drop, and they pop off pretty easily when manually pressured, some cheeply manufactured products barely had the stuff even mounted, but it came up Easy  the metal to metal contact with some of the manufactured stuff was very poor too, i bet Mr Milkey could tell more about that.

lots of my stuff is stuck down with "the Pink Stuff" from the copper coloration added, so i can guess the formula used that time. havent had any problems yet.

I Always use WAY to much of any of it, its hard to try and 50-50 mix epoxies in teeney quantities, and the cure time makes it a one shot deal, so after clamping i always see $$$ going out the window. If you were assembling within the cure time, many items, and used Really THIN and only nessisary ammounts instead of piles of it, the 2 tubes of AS epoxy will go Very very far, many many items. 
If you can pre-set-up a process for thin coating, alignment, and clamping, and move really fast, or work with help, a single mix of AS would go far, but without speed its to late to get a mass done before a partial cure, and a partial cure is already to late for a great thin layer on clamping.


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## Brum (Nov 29, 2007)

Also check out the Loctite lineup, I've got some laying around (got it for free, wasnt cheap though). 
It comes in a pretty big tube, long shelf life, 1-day cure and works perfect according to the guy I got it from.


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## ZuluWhiskeyFox (Nov 29, 2007)

I use JB Weld straight up, no mix added. For potting in sandwiches I use JB Kwik. Never had a problem with it. 

zwf


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## Lighthouse one (Dec 1, 2007)

Another vote for the DX thermal glue. I just did a Seoul Led. Running 1.2 amps...works great. Glue does dry a bit fast, but it's great not having to mix little batches of epoxy all of the time. The Glue is also good for lots of regular stuff. A bit rubbery when dry- but holds real good.


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## legtu (Dec 2, 2007)

i'm thinking that it might be better to just use *any* thermal compound under the LED and use epoxy on the sides to hold it rather than mixing epoxy and a thermally conductive component.


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## LEDite (Dec 3, 2007)

I use a 2-Part 30 minute Epoxy with 800 grit aluminum oxide filler.

2 parts mixed epoxy to 1 part alum. oxide.

Larry Cobb


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## uk_caver (Dec 5, 2007)

Looking at the material safety data, JB Weld is already fairly heavily mineral-filled.

I don't run my LEDs too hard, and for years I used JB weld for sticking them to aluminium plates with no problems.

I switched to using AA thermal epoxy, but mainly for the convenience of having something fast-setting. Though it is more expensive, the amount used per product and the cost is still minimal, and with the tiny syringes, it's easy to make up just the right amount, so there's no waste.


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## lukevsdarth (Dec 6, 2007)

Thanks for the info never knew a local hardware/autoparts store could have what I need to glue stars. 

Thanks, Fred:thinking:


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## NigelBond (Dec 6, 2007)

Can anybody tell me if jb weld is electricaly conductive? I have some but i've never tried to use it in this way. The packaging says that it can be used to insulate electrical components but I find that hard to belive if it's filled with metal.

I remember seeing on a computer hardware forum many years ago, there was some dude that made his own thermal epoxy by mixing 5 minute epoxy with arctic silver thermal compound. I think it was arctic silver 3. Might be worth testing. Thermal compound is much cheaper than thermal epoxy


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## uk_caver (Dec 6, 2007)

I've used leftover JB Weld to cover some components I normally coat in regular epoxy, and it's never caused any problems even in high-impedance areas.

It only seems to have 10-20% iron powder in one of the components, so that's only 5-10% in the final product. All the other fillers seem to be nonconductive metal oxides, carbonates, etc.

Even AA thermal epoxy, which isn't exactly cheap, doesn't cost much per application compared to the cost of the LEDs.


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## OddOne (Dec 6, 2007)

Bear in mind, whether you're talking about nonpermanent junction material or permanent mounting, the thermal junction has to be as thin as practical. From that perspective, you can make a little Artic Alumina go a very, very long way.

oO


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## frenzee (Dec 6, 2007)

JB Weld's electrical properties are very unpredictable. You might set your component and your DMM will tell you everything will looks fine. Then when it sets it tells you that you have a short. This has happened to me at least a dozen times. The frustration, not to mention the cost of the lost component simply isn't worth it. My suggestion is to go with AA or AS as it goes a long if used properly, i.e. both surfaces prepped (lightly sanded, IPA cleaned and wetted), and a very thin layer is applied and light pressure is applied during curing. If you want to improve on AA's performance add 25-50% by weight 200-300 mesh diamond powder to the mix.


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## spun (Aug 3, 2009)

to continue an old thread... 
a link with testing results from using diamond dust to make their own thermal compound. impressive results.
http://inventgeek.com/Projects/DiamondGrease/overview.aspx


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## saltytri (Aug 4, 2009)

I've used West System #420 aluminum powder in epoxy. It's fine as dust and can be mixed into a paste that allows a very thin film between smooth surfaces. Buy it here, among other web vendors:

http://www.westmarine.com/webapp/wc...4?&cid=chanintel&ci_src=14110944&ci_sku=28514


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## Norm (Aug 4, 2009)

Mr_Light said:


> I highly recommend this which I have used to Glue dozens of Stars into many modded lights.
> 
> FUJIK Silicone Thermal Glue (50ml Grease-Like) $7.81
> http://www.dealextreme.com/details.dx/sku.4579


This stuff has very poor thermal performance, not too bad for lower power LEDs no where near the performance of Arctic Alumina. Definitely don't use it for P7s.



mds82 said:


> does this stuff actually dry, and does it dry hard
> 
> 
> In the past i have always used JB Weld to hold the parts together because the strength is great on that stuff, however its thermal conductivity isnt that good afterall.
> What other options are out there?


I sets like silicon, firm but doesn't not hard like AA.
Norm


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## darkzero (Aug 4, 2009)

I too have been using alumina oxide powder for years & on everything. The Shoppe sells it in small quantities if you don't want to purchase a large quantity.


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## Justin Case (Aug 5, 2009)

https://www.candlepowerforums.com/posts/2716057


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