Thermal Adhesives

[NightShift]

So what do all you modders use to secure the LEDs to heatsinks - arctic silver thermal adhesive/arctic alumina thermal adhesive?

 

[Rothrandir]

arctic silver...it conducts the heat better

expensive stuff though!

 

[Nerd]

The difference with either Artic Silver or Artic Alumina is not a lot. But the price is another thing. If you want the best, there is always a premium.

 

[Rothrandir]

i would (and do) go witht the arctic silver, as every little bit helps, and with such a small surface area to work with, and with the heat produced (especially with overdriving) you want the best thermal transfer possible.

 

[Monsters_Inc]

Go to any computer hardware overclockers site and you'll see reviews of 'Thermal paste', etc.

Nanotherm comes to mind, similar to AS in performance, costs a little less.

 

[lambda]

I started out mixing my own with 20 min epoxy and thermal grease. It works pretty well, but varies in quality by the mix.

I swear by Artic Silver for mounting Luxeons. Especially when mounting $25-$40 5W Luxeons, the little extra cost for AS is well justified.

 

[Minjin]

How about electrically conductive epoxies?

Mark

 

[hotfoot]

Electrically conductive epoxies are not a good idea unless you want to short out your luxeon. The emitter slug is not electrically neutral and it would be best to use a electrically non-conductive epoxy if you are mounting your emitter to a metal surface, particularly in multi-emitter situations.

Its for this reason I prefer Arctic Alumina over Arctic Silver - AA uses a electrically insulative ceramic-filled adhesive compound and runs no risk of shorting anything.

 

[Slick]

I checked out the perfomance curves between Alumina and Silver and there was very little difference. Alumina is electrically NON-conductive along with being more economical to use so I go with it. No problems yet...

 

[hotfoot]

Originally posted by Slick:
I checked out the perfomance curves between Alumina and Silver and there was very little difference. Alumina is electrically NON-conductive along with being more economical to use so I go with it. No problems yet...

<font size="2" face="Verdana, Arial">Alumina is more economical? I thought AS was the cheaper one. Maybe I'm getting ripped off.

BTW, the performance curves between toothpaste, cheap silicone heatsink compound and any of the Arctic goops don't differ very much either, at least according to Dan's data. The pro stuff just lasts longer (ie. doesn't dry up/crumble and flakeout).

 

[NightShift]

Does anyone know if CompUSA carries Arctic Silver products? I pretty much looked and didn't see it. One would expect a leading computer store that carrys computer everything to have it.

Now I have to find a place on the web to buy it...

 

[lambda]

NightShift,

Try http://becooling.safeshopper.com/index.htm , fast service.

 

[sunspot]

http://www.svcompucycle.com/thermalgrease.html free shipping

 

[Hemingray]

I have been trying Arctic Silver expoxy, seems to do the job well. Got it at www.cpufx.com
They are located in eastern Massachusetts.

/ed brown in NH

 

[Doug S]

Originally posted by sunspot:
http://www.svcompucycle.com/thermalgrease.html free shipping

<font size="2" face="Verdana, Arial">The SVC folks have great prices. They only offer the free shipping on some Arctic products but unfortunately not on the adhesive. Worst, their shipping policy statement says that they only charge actual shipping and pride themselves on not trying to make money off of the S&H but if you use their online ordering and select USPS 1st class as the shipping method, they compute $6.25 shipping for this 1 oz item. Go figure.

 

[Rothrandir]

i got some from somewhere on sale for around $8, the s$h was 7 however...

aren't even the white-type luxeons electrically isolated?

i know the red and red/orange are positive which is possibly the stupidest thing i have ever encountered...

 

[hotfoot]

Originally posted by Rothrandir:
aren't even the white-type luxeons electrically isolated?

i know the red and red/orange are positive which is possibly the stupidest thing i have ever encountered...

<font size="2" face="Verdana, Arial">rothrandir,
nope - the whites aren't insulated either. I know, its incredibly odd and very un-smart. I can say this with certainty because I've done something like 50-60 tri-emitter "mods" (more like prototypes, actually) and quite a few of my early pieces suffered from weird ground problems because I chose to ignore the datasheet info.

Now, if I'm in a multi-emitter situation, I'll ALWAYS find a way to insulate each emitter's slug before planting it on an electrically-conductive surface. I will admit that I frequently still omit the insulation if I'm working with single emitters, though.

 

[Slick]

Hotfoot - I'm curious if your tri-emitter mods were wired in series or paralell?

I've never had any problems mounting a SINGLE white emitter directly to the ground plane..

 

[Minjin]

My question still stands. Can anyone recommend an electrically conductive epoxy/glue?

As for mounting luxeons (which my above question does not concern), the base can only be three different things. Connected to either of the two leads, or not connected. If its electrically isolated, then all is well. If its not, then its simple enough to mind current flow and make sure it goes through the luxeon rather than around it.

Mark

 

[Doug S]

Originally posted by Minjin:
As for mounting luxeons (which my above question does not concern), the base can only be three different things. Connected to either of the two leads, or not connected. If its electrically isolated, then all is well.
Mark

<font size="2" face="Verdana, Arial">I can think of two more plausible possibilities. It can be connected to the die via a PN junction to either of the power leads.
It would be hard for anyone to recommend a conductive epoxy without knowing what bulk conductivity you need for your intended application.