# super glue as thermal expoxy



## raggie33 (Feb 23, 2004)

well thats all i had.so i super glued a luz 1 water to a big heat sink from a stereo or something i foget but its was big well that heat sink got hot as hect . proveing to me it remved heat from lux i was overdriveing it very very high and it ran all night to batts died .was bright as hect so is it posable that super glue trasnfers heat?


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## kakster (Feb 23, 2004)

I think Dat2zip did an experiment once, and used spit to transfer the heat, so i think superglue would be fine. But i'd bet that a superglued Lux would degrade faster than one that was epoxied with proper thermal stuff.


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## LightScene (Feb 23, 2004)

It sounds like you proved that super glue works. I didn't think it would hold up to high heat. But I know it does a good job of electrical insulation.


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## Al_Havemann (Feb 23, 2004)

It works well. I used it to mount a heat sink on my 5w bike light. Dispite lots of use, it never overheated.

Al


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## NewBie (Feb 23, 2004)

Air:
Thermal conductivity 0.025-0.031 W/mK

Fiberglass:
Thermal conductivity 0.04 W/mK

Superglue Loctite 382:
Coefficient of thermal conductivity, ASTM C177, 0.11 W.m-1K-1 
Glass transition temperature, ASTM E228, ºC 130
(*most epoxies transistion around 50-65 ºC)
(some high temperature epoxies transition 90 ºC and above-specialized)
(glass transition temperature is when material gets soft and 
bonds get weak)

http://www.loctite.se/tds/382.pdf


Picked this as a typical epoxy Loctite Hysol 3450:
Coefficient of thermal conductivity, ASTM C177, 0.28 W.m-1K-1 
Bond strength at temperature is shown on datasheet chart.
http://www.loctite.at/tds/3450.PDF

Nylon (Polymide):
Thermal conductivity 0.24 W/mK

Pure Water:
Thermal conductivity 0.58 W/mK

Wakefield 120 Thermal Grease:
Thermal Conductivity 0.735 W/mK
http://power.ece.uiuc.edu/Balog/images/How%20to%20keep%20your%20cool%20when%20working%20with%20power%20electronics.pdf

Fused Silicon Dioxide:
Thermal Conductivity 1.4 W/mK

Dow Corning SE4447 CV Thermal RTV:
Thermal Conductivity 2.5 W/mK
http://www.dowcorning.com/DataFiles/090007b58021adab.pdf

Artic Silver Thermal Epoxy:
Thermal conductivity. Greater than 7.5 W/mK
http://www.arcticsilver.com/arctic_silver_thermal_adhesive.htm

Stainless Steel:
Thermal conductivity 15-25 W/mK

Loctite Thermal Adhesive QMI 5030:
Thermal Conductivity, 25 W/mK
http://www.loctite.com/int_henkel/loctite/binarydata/pdf/lt3758a_ThermMgmt.pdf
http://www.loctite.at/tds/QMI5030.pdf

Alumina (Aluminum Oxide):
Thermal Conductivity 30 W/mK

Lead:
Thermal conductivity 34.7 W/mK

Carbon Steel:
Thermal conductivity 43-64 W/mK

Aluminum:
Thermal Conductivity 190 W/mK

Aluminum Nitride:
Thermal Conductivity 260 W/mk


Boron Nitride:
Thermal Conductivity 250-300 W/mk

Copper:
Thermal Conductivity 386 W/mK

Silver:
Thermal Conductivity 406 W/mK

Diamond:
Thermal Conductivity 500- 1000+ W/mK


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## Justintoxicated (Feb 23, 2004)

mix in some Artic Silver with it /ubbthreads/images/graemlins/smile.gif


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## raggie33 (Feb 23, 2004)

[ QUOTE ]
*SureFireRocks said:*
Air:
Thermal conductivity 0.025-0.031 W/mK

Fiberglass:
Thermal conductivity 0.04 W/mK

Superglue Loctite 382:
Coefficient of thermal conductivity, ASTM C177, 0.11 W.m-1K-1 
Glass transition temperature, ASTM E228, ºC 130
(*most epoxies transistion around 50-65 ºC)
(some high temperature epoxies transition 90 ºC and above-specialized)
(glass transition temperature is when material gets soft and 
bonds get weak)

http://www.loctite.se/tds/382.pdf


Picked this as a typical epoxy Loctite Hysol 3450:
Coefficient of thermal conductivity, ASTM C177, 0.28 W.m-1K-1 
Bond strength at temperature is shown on datasheet chart.
http://www.loctite.at/tds/3450.PDF

Nylon (Polymide):
Thermal conductivity 0.24 W/mK

Pure Water:
Thermal conductivity 0.58 W/mK

Wakefield 120 Thermal Grease:
Thermal Conductivity 0.735 W/mK
http://power.ece.uiuc.edu/Balog/images/How%20to%20keep%20your%20cool%20when%20working%20with%20power%20electronics.pdf

Fused Silicon Dioxide:
Thermal Conductivity 1.4 W/mK

Dow Corning SE4447 CV Thermal RTV:
Thermal Conductivity 2.5 W/mK
http://www.dowcorning.com/DataFiles/090007b58021adab.pdf

Artic Silver Thermal Epoxy:
Thermal conductivity. Greater than 7.5 W/mK
http://www.arcticsilver.com/arctic_silver_thermal_adhesive.htm

Stainless Steel:
Thermal conductivity 15-25 W/mK

Loctite Thermal Adhesive QMI 5030:
Thermal Conductivity, 25 W/mK
http://www.loctite.com/int_henkel/loctite/binarydata/pdf/lt3758a_ThermMgmt.pdf
http://www.loctite.at/tds/QMI5030.pdf

Alumina (Aluminum Oxide):
Thermal Conductivity 30 W/mK

Lead:
Thermal conductivity 34.7 W/mK

Carbon Steel:
Thermal conductivity 43-64 W/mK

Aluminum:
Thermal Conductivity 190 W/mK

Aluminum Nitride:
Thermal Conductivity 260 W/mk


Boron Nitride:
Thermal Conductivity 250-300 W/mk

Copper:
Thermal Conductivity 386 W/mK

Silver:
Thermal Conductivity 406 W/mK

Diamond:
Thermal Conductivity 500- 1000+ W/mK 

[/ QUOTE ]
i dont understand does that mean super glue is real bad or good? i need the homer simpson version please /ubbthreads/images/graemlins/smile.gif


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## raggie33 (Feb 23, 2004)

o btw i had itoverdrived at 4xaa nimh around 4.8 volts fully charged of charger it was so bright but i used a reflector that was wrong it didnt throw far but lighted up a big area


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## tonyb (Feb 23, 2004)

How about Silicon Carbide (Sandpaper)?


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## EvilLithiumMan (Feb 23, 2004)

Super Glue is real bad, 'Homer' /ubbthreads/images/graemlins/smile.gif . But that doesn't mean you can't use it - what really counts is the percentage of metal to metal contact. The Super Glue is only occupying the air gaps that exist. Whether those gaps comprise 10% or 90% of the contact area is anyone's guess. But the fact that excellent heat transfer exists with your setup leads me to guess you have a large percentage of metal to metal contact, and that is where the majority of the transfer occurs.

I've used Super Glue on both of my Hotlips builds. The heat transfer is excellent not because of the Super Glue, but because both mating surfaces are flat.


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## Justintoxicated (Feb 23, 2004)

I don't understand the chart, that or I don't trust it...It has been shown time and time again that those lead thermal pads compleatly suck at thermal transfer and that artic silcer is at least 10x better....Acodring to that lsit it appears this is not the case.

Also wth? locktight works 4 times betteer than Artic Silver? For some reason I highly doubt this. It makes no sense what so ever. Why would people not use locktight on their CPU's etc instead of buying expensive thermal past?

Something is wrong or im not understanding the chart, there is no way locktight or lead is better at transfering heat than artic silver!


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## Bushman (Feb 23, 2004)

intoxicated presents a good question here, I have loctite at home but I would have to spend $10 plus shipping to get the artic alumina or artic silver


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## NightStorm (Feb 23, 2004)

Gentlemen,

The Loctite Corporation produces many products other than their infamous thread locking compounds. Feel free to peruse their web site .

Dan


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## LightScene (Feb 23, 2004)

This is just another example of where theory collides with actual practice. The Luxeon is super-glued to a heat-sink, and the heatsink gets hot as heck. That tells me all I need to know - superglue works really well. 

If this chart claims that diamonds work better than super-glue, who cares? Diamonds are not adhesive.


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## Justintoxicated (Feb 24, 2004)

I don't care wtf locktight makes..There have been numerous studies in the past that show only one uncommon thermal compound to work really well, and thats shin-etsu...How many times were these compounds applied in this chart? just one sample for each reading? A good test would use a minimum of 10 PROPER applications. Superglue as said has little to no thermal properties, I have even read that peanut butter would work better. If only it was adhesive! Well im sure superglue will work, it is just not very good, at least some AS should be mixed in to help a little...or rather some superglue should be mixed in with AS..AA..or other non epoxy to really transfer heat well. if the emitter heats up enough, it will transfer heat to almost anything.


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## Negeltu (Feb 24, 2004)

Goodness


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## IsaacHayes (Feb 24, 2004)

Good point. If it heats up enough, it will transfer heat to anything. May not transfer it quick enough with certain things, but still warm up and fool you like it's working.


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## dat2zip (Feb 24, 2004)

Lightscene,

Careful there. The loctite under the Luxeon is ??? of which we don't know the properties. I'm sure Lumileds chose it for many reasons. One for sure is the automated machines that dispense them. The other I'm sure is for the thermal properties. That is not ordinary loctite.

One thing to note and has been pointed out above is not necessarily the thermal compound that is used, but, more sigficantly is the actual thickness of the joint. If both surfaces are very flat then you will have a more ideal metal to metal contact which if you don't care about isolation is very good.

loctite works for some of you only for the fact that your joint or surface to surface is probably very thin.

If you blob'd some loctite and sat the Luxeon on top of the blob without squishing it down, I think you would see a completely different result and in this case the thermal efficiency of the goo in this case loctite, would perform very badly.

I've always said that spit could perform better than many adhesives. My only caveot is that the thickness would be less than 0.001" thick or a very thin layer. In that case it would work better than a 0.10" layer of AA or AS probably.

Keep it thin and you could get by with many substitutes. In some cases the slug must be isolated so you could be playing with fire and smoke your precious LED if you do end up with a metal to metal contact. Be aware of what you are doing.


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## LightScene (Feb 24, 2004)

dat2zip, I was referring to the original post in this thread. He used super-glue and it worked. The proof is in the pudding.


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## gadget_lover (Feb 25, 2004)

Wouldn't it be fair to say that the Arctic Alumina will typically do better than super glue simply because it will fill any small gaps, scrtaches, or imperfections, thus increasing the area of thermal transfer?

On the other hand, it should be OK if the contact area is large enough and the heatsink can absorb or radiate enough heat to keep the temperature below superglue's "Glass transition Temperature" of 130 C. 

Daniel


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## illumiGeek (Feb 25, 2004)

[ QUOTE ]
*LightScene said:*
dat2zip, I was referring to the original post in this thread. He used super-glue and it worked. The proof is in the pudding. 

[/ QUOTE ]

Yes, and my father smoked all his life and never got cancer. That proves smoking is safe right?

/ubbthreads/images/graemlins/jpshakehead.gif

It worked because he had sufficient slug to heatsink contact. Some people get lucky. That's all.


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## NewBie (Apr 17, 2005)

Sorry for taking so long to respond raggie, super glue can be really bad or somewhat decent, depending on the application. By itself, it's pretty poor.


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## Lynx_Arc (Apr 17, 2005)

one other problem with super glue is it isn't waterproof. There is a chance if moisture got into a joint it could come undone.


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## Krit (Apr 17, 2005)

I used thermal metal epoxy without problems. /ubbthreads/images/graemlins/smile.gif


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## VidPro (Apr 18, 2005)

i know one good reason to not use superglue, over time, or maby because of expansion and contraction, it falls off.

i have used it for sinks and lux STAR placement, and you can get a THIN layer FAST, and locked down before a buch of air flows back into the joint.
BUT
it always fell back off over TIME.

in my computer i almost shorted out the motherboard when a superglued sink came crashing down. it had thermal compound in its center, and superglue around the edges to hold it in place. it was firm as a rock after applied, but over time it met its demise.

the stars that i superglued stayed and worked well at first, i thought they would never come off. but when i needed them a year later, i just pushed and it fell right off. which was kinda cool /ubbthreads/images/graemlins/smile.gif at the time.

superglue and superglue gell was quickly available all the time here, and so i applied it often.
yet , i cant think of one item that is still together that i used it on , so i quit using it.

had some of the same problems with normal cheapo expoxies too, age time , heat expansion, and the brittleness of it.


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## twentysixtwo (Apr 18, 2005)

Key to heat transfer is to have your adhesive layer as thin as possible. If both surfaces are perfectly flat and smooth, thermal paste is irrelevant since the layer is zero.

Better to have a ultra thin layer of CA than a thick layer of AA epoxy, though, as you point out, super glue, over time, is less than super. When you glue, make sure you squeeze out the air and excess goop.


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## cy (Apr 18, 2005)

I've posted this several time before, but here goes again...

best use of superglue is for plastic edges only. 

use AA grease or other silicon based contact paste for metal part of luxeon slug. aply only enough to cover metal slug. 

press down and hold. aply small drop of superglue to crack made by plastic luxeon base and heatsink. superglue will wick all the way around luxeon. press down for aprox. 2 minutes and you are done. 

you now have the best of both. if you have done correctly, luxeon is solidly glued down with ability to remove luxeon without damage later.


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