# how "permanent" is artic silver thermal adhesive?



## poolman966554 (Dec 1, 2013)

as topic states, im looking to mount 12 xmls in u channel for an offroad light. im curious as how hard it would be to pry an led off if one were to fail.



whats your preferred method of using screws? small heads? or neoprene washers to avoid a short? i thought i had it all figured out, but seem to find small snags everywhere!

Thanks!


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## znomit (Dec 1, 2013)

Not permanent.
If you can get something under the LED star you can usually pop it off.


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## m4a1usr (Dec 1, 2013)

Depends on how much room around the LED you have. Chances are your going to have to use something like a chisel to get it off. Artic is darn good stuff. And if its set on a clean surface with a slight roughness it adheres well. So once set its considered permanent. However if the surface is fairly smooth and oily, like aluminum, it is possible to get it off. I have glued to many aluminum reflectors with Artic and been able to get the adhesive to break or fracture if needed. Clean up will require patience.


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## Illum (Dec 1, 2013)

Unless space is an absolute premium, I usually opt for designs that fastens the LED with screws as opposed to an epoxy joint. For one, if the LED goes, repair is a breeze, if it doesn't, upgrades are a breeze. Arctic silver paste works well, but it still leaves a bit to be desired.


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## TEEJ (Dec 1, 2013)

If the led is thermally bonded to copper, etc, the heat sinking does work better though, hence the pastes' popularity.


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## mds82 (Dec 2, 2013)

If the LED is mounted to a MCPCB then you will be able to remove it if needed. You will need a screw driver and hammer most likely, but it will pop off. You will need to scrape off the old glue after


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## alpg88 (Dec 2, 2013)

it is possible, but hard to remove, i had amc driver glued to heatsink with AS adhesive, when i tried to remove burned driver it took tops of amc chips with it.


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## DellSuperman (Dec 2, 2013)

Freezing it will make it brittle & easier to crack & remove

- JonK


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## RoGuE_StreaK (Dec 2, 2013)

DellSuperman said:


> Freezing it will make it brittle


Could be an issue in poolman's case then? Is this for the snow-plow?


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## poolman966554 (Dec 2, 2013)

Rogue, it is for the quad plow.

thanks for all the responses guys. i guess i will try to find some screws at the hardware store with small enough heads it wont short the terminals, and apply AS5 compound to the stars. 

Is there anything i should consider when mounting with metal screws? ex: is there continuity from side of star? i dont have my meter with me to check right now. These are cree t6-3b

Edit: the leds were purchased premounted on stars from fasttech. i know it does not conduct through backplate, never checked the sides though.


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## mds82 (Dec 2, 2013)

If you have the artic silver glue then i would just use that. It will be the easiest option so you sont need to find screws, tap the aluminum etc. The chances of a LED failing are slim. I wouldnt go through the extra effort and cost for screws. I run a small business and i've had 50,000+ LED's mounted with glue and no issues with them.


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## DIWdiver (Dec 2, 2013)

Socket head cap screws probably have the smallest head of any standard screw. I've found that #4 ones were fine on my stars, but YMMV. 

All of the bare aluminum (or copper) is conductive, it's just not connected to the LED. The way the star is constructed is by gluing a very thin circuit board to the metal plate. The LED is then soldered to the board. The fiberglass of the circuit board insulates the LED and the terminals from the metal substrate. The problem is that the copper plating on the top of the board (which connects the LED to the terminals) can run pretty close to the cutouts for the screws, depending on the star, and a bare screw head can puncture the soldermask (the paint on top of the board) and connect the terminal to the heatink. You can actually see where the plating is if you look very closely; you'll see a slight ridge at the edge of the plating. If in doubt, use nylon (not neoprene) washers. No need to worry about the edge of the star, only the top.


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## DIWdiver (Dec 2, 2013)

mds82 said:


> If you have the artic silver glue then i would just use that. It will be the easiest option so you sont need to find screws, tap the aluminum etc. The chances of a LED failing are slim. I wouldnt go through the extra effort and cost for screws. I run a small business and i've had 50,000+ LED's mounted with glue and no issues with them.



The chances of an LED failing without being abused is slim. Unfortunately, with DIY folks, especially beginners, the chances of abuse are not so slim.


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## poolman966554 (Dec 2, 2013)

mds82 said:


> If you have the artic silver glue then i would just use that. It will be the easiest option so you sont need to find screws, tap the aluminum etc. The chances of a LED failing are slim. I wouldnt go through the extra effort and cost for screws. I run a small business and i've had 50,000+ LED's mounted with glue and no issues with them.



I have ArticSilver 5 compound(for cpu's etc.), not the adhesive. i was just considering it, or even thermal pads..

DIWdiver, thanks for the tip on socket head cap screws. ill use a nylon washer if i cant find anything suitable.


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## hellokitty[hk] (Dec 2, 2013)

I pulled off a 20mm star from a copper block with my hands after trying hard enough.


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## Paul Baldwin (Dec 3, 2013)

I haven't used the artic but have used the Fujik stuff quite a lot and it adheres VERY well. If you have space I have found that a good adjustable spanner is ideal to remove stars! Just place it vertically over the led, adjust the jaws so that it grips the star and twist. :thumbsup: Way better than hammers and chisels, blades etc imo, tried that, too easy to damage the heatsinks surface that you then have to repair before you can use it again.


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## kongfuchicken (Dec 8, 2013)

There's an old trick with the artic silver/alumina two part epoxy in that you can make a 50/50 mix with the non-adhesive type ceramique and the epoxy and it will make it weak enough that you can easily remove it without damaging whatever your heatsink is glued to but still solid enough that there's very little risk for things to fall off on their own. 

Computer overclockers like to use this method to install small pieces of custom-cut heatsinks on VGA card memory chips when using a watercooling block but often have to remove them later when they need to return the card back to stock conditions if they want to resell the parts without risking damage. Personally, I have tried it on a LED star and it seems to work like a charm. Also, freezing does help as well.


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## alpg88 (Dec 9, 2013)

i always use flat head screw, m2,5, and i cut thread on heatsink myself, done it hundreds of times, never had a short.


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## Epsilon (Dec 11, 2013)

hellokitty[hk] said:


> I pulled off a 20mm star from a copper block with my hands after trying hard enough.



When both surfaces are lapped and degreased with acetone, you will not be able to get it off with you hands. I tried it with a pair of pliers and destroyed the LED when I slipped off.

The way you can remove the PCB from the heatsink: Use a knife and pry it between the heatsink and the PCB. If needed (I had too), use a hammer to wedge it in between.
You probably have to lap the heatsink / PCB again to get a nice flat surface again.



alpg88 said:


> i always use flat head screw, m2,5, and i cut thread on heatsink myself, done it hundreds of times, never had a short.



I don't like to tap and drill in copper, bad expieriences with broken taps (once) and drills (lots) in preciously carved workpieces . I try to reduce any drilling with small diameters in copper to a minimum. Granted, it will give a little better thermal path than with the AS Adhesive .

The Fujik (color: "whait" lol) is easy to separate, it is not that strong .


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## alpg88 (Dec 11, 2013)

m2,5 isn't the smallest thread i cut, when i used led tech 16mm copper stars i used m1,6 die. 

copper is harder to cut thread into, that is true, i also not big fan of cutting thread in copper, i use nuts\machine screws for copper heatsinks.


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## oscillator (Dec 12, 2013)

decreases over time but probably doesnt become ineffective, more like 50 percent efficient after 7 8 years, at a guess. anyone know better?

you can buy permanent glue arctic adhesive


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## mds82 (Dec 13, 2013)

google search for it, there are tons of places that sell it. you can buy direct from Arctic Silver and get different versions as well, 5 minute, 30 minute 60 minute setup times. those are for wholesale account and large quantities around 30cc at least.


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## Walterk (Dec 15, 2013)

I always dislike screwheads when mounting a star. I am always afraid pulling them to hard to crack the dielectric layer and forming a short-circuit.
Prefer using nylon rings inbetween bolts and star, but often available space is cramped.
Bolts or screws do help a big lot to make the layer between sink and star as thin as possible.


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## idleprocess (Dec 25, 2013)

I've used arctic alumina thermal epoxy for numerous projects as the sole source of attachment mixed on-the-fly in the best 50/50 mixture I could eyeball. Haven't had it fail me yet.

Most challenging would probably be my driveway lighting project where I glued the LED MCPCB's to aluminum sample jars, themselves glued to the meager heatsinks... all mounted upside-down. These things run 24/7 48-52 weeks of the year including the hot Texas summers.


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