# super-glue Cree star to heatsink



## mikeh (Jun 13, 2008)

After applying drop of silver heatsink paste to the MCPCB star, and pressing it hard against the heatsink, I put superglue on the edges of the star/heatsink join.
Now I'm asking how smart that was 
I reckon that if the star and heatsink surfaces were perfectly flat, you could get away with just superglue and nothing else to join them. The glue has very low viscosity, so would be very thin.
But in this case, I needed the thermal paste to fill the gaps.
So is there any problem with using superglue, rather than screws, to hold the star on the heatsink? Its a lot easier. Heat should only be up to 60degC max at the glue.


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## JamisonM (Jun 13, 2008)

I don't think you should have any problems as long as the glue has a good hold of the emitter and can stand the temperatures you'll put it through. I think some thermal adhesive would've been better though. If you're brave, you could also try doing something like this, but I think it's more trouble then it's worth.


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## allburger (Jun 13, 2008)

Ive done something similar to what you are talking about. Ive done a couple ssc p4's on heatsinks and mag drop ins. What i did was literally put thermal paste and super glue down on the surface and take a tooth pick and mix them, then drop the led onto it. Ive had awesome luck, never has the led overheated and turned blue!!!!!!!


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## Mr_Light (Jun 13, 2008)

I highly recommend the following Thermal Glue from DX. It's simple (no mixing), and it works (I've used it on at least 50 LED lights including P7s). This one tube should be enough for about a hundred LEDs.
http://www.dealextreme.com/details.dx/sku.4579
FUJIK Silicone Thermal Glue (50ml Grease-Like) Price: $8.44


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## LukeA (Jun 13, 2008)

Mr_Light said:


> I highly recommend the following Thermal Glue from DX. It's simple (no mixing), and it works (I've used it on at least 50 LED lights including P7s). This one tube should be enough for about a hundred LEDs.
> http://www.dealextreme.com/details.dx/sku.4579
> FUJIK Silicone Thermal Glue (50ml Grease-Like) Price: $8.44



I love that stuff! :twothumbs 5-minute cure, remains flexible.


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## rizky_p (Jun 15, 2008)

Mr_Light said:


> I highly recommend the following Thermal Glue from DX. It's simple (no mixing), and it works (I've used it on at least 50 LED lights including P7s). This one tube should be enough for about a hundred LEDs.
> http://www.dealextreme.com/details.dx/sku.4579
> FUJIK Silicone Thermal Glue (50ml Grease-Like) Price: $8.44



Yeah i use that one too, strong enough but not permanent


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## eprom (Jun 15, 2008)

I am using Pattex superglue as a thermal adhasive (no other compound or adhasive). All my mods made with Pattex. It gives a electrical insulation and very good thermal conductivity. I have fixed my P7 to DHS Heatsink with Pattex for my mag mod and drive it near 4A for 30 minutes.


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## mikeh (Jun 15, 2008)

eprom said:


> I am using Pattex superglue as a thermal adhasive (no other compound or adhasive). All my mods made with Pattex. It gives a electrical insulation and very good thermal conductivity. I have fixed my P7 to DHS Heatsink with Pattex for my mag mod and drive it near 4A for 30 minutes.



Thanks, that's interesting. I guess 4A is a good test  Was this a bare emitter, or on base?
Anything special about Pattex?
The superglue is great at wicking into tiny gaps, but I worry that if the surfaces are slightly uneven, the glue-filled gaps may be too thick. Thermal paste under the star, plus glue at edges seemed a good compromise.
So long as the paste stays in place over repeated heat/cool cycles.


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## eprom (Jun 16, 2008)

Hi mikeh,

* Yes, it's bare emitter on DHS Heatsink,
* Nothing special with Pattex,
* Yes, surfaces must be smooth and clear, yes key point is very thin film of superglue,

* Yes, using ThermalPaste plus Superglue seems good solution, but i like strongly fixed emitters


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## OldNick (Jun 22, 2008)

My experience says don;'t, if you are going to use any plastic reflectors or lenses. The stuff ruined 3 lenses for me. This was after I left it for a long time. I fear it outgasses when heated or warmed.



Nick



mikeh said:


> After applying drop of silver heatsink paste to the MCPCB star, and pressing it hard against the heatsink, I put superglue on the edges of the star/heatsink join.
> Now I'm asking how smart that was
> 
> So is there any problem with using superglue, rather than screws, to hold the star on the heatsink? Its a lot easier. Heat should only be up to 60degC max at the glue.


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## mikeh (Jun 22, 2008)

OldNick said:


> My experience says don;'t, if you are going to use any plastic reflectors or lenses. The stuff ruined 3 lenses for me. This was after I left it for a long time. I fear it outgasses when heated or warmed.



Ah - good point. I'm sure I've seen similar damage of plastic from superglue, but i think it occurred early (within 24 hrs?)
But I'm using those clip-on optics, and have plenty spare from a 10-pack fortunately. The glue is well away from the optics, but could be a problem if all enclosed in an airtight casing. I'll be sure to give it plenty of time to dry before clipping the optics to the emitters, and use no glue there. Thanks.


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## OldNick (Jun 22, 2008)

I have the optics mounted on about 19mm long tubes, which are glued to the star. The optics pop in.

Be careful. As I say, the damage occurred over time (weeks). I waited for a couple of days before putting the optics in. I used the lights quite a bit, without noticing a problem. However I found it very noticeable when I had not used the lights for a few weeks. They had been gradually deteriorating.

I would still (and I am not alone) recommend the silicones for the optic mounts, and DX's heat-transfer silicone (or Arctic Silver, which is more expensive, but the ultimate. It does have the problem, that you will probably not be able to remove the LED Star.from the heatsink.)

Nick


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## IMSabbel (Jun 22, 2008)

Just to put something in that people might be missing:

Every thermal paste/glue sucks compared to metal.
Reverse conclusion:
As long as you can get the layer thin, you can use _anything_ that fills the surface imperfections with good sucecss.

Be it superglue, toothpaste, epoxy, nutella, ect.

they all hover between 0.5 and 0.05 K/Wm.

Getting good pressure on the led so the created layer is thin, and taking care that there arent air bubble in it is MUCH more important than what you use.


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## mikeh (Jul 3, 2008)

OldNick said:


> My experience says don;'t, if you are going to use any plastic reflectors or lenses. The stuff ruined 3 lenses for me.



Nick - I just found the fix for this. Try cleaning the lenses with acetone.
(ie nail-polish remover.)


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## OldNick (Jul 3, 2008)

mikeh said:


> Nick - I just found the fix for this. Try cleaning the lenses with acetone.
> (ie nail-polish remover.)



Oh dear, and I'm fresh out! <G>. But paint thinners works as well.

HAH! I assumed it was etching, not a deposit. These were K2 reflectors, and I have moved on to Cree, so I just stuck them in the drawer.

Thanks for that and handy to know.

Nick


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