Heat sync thermal compound for Alumilium panel with LEDs?

I am making my own daylight equivalent LED light that uses around 30 watts. I have simply got an aluminium panel that is 250 x 250mm and put 12 LED strips each with 12 LEDs on them. This does get to the point where it is just a little to warm to touch on the back. I will eventually be fixing this on an old lamp that used to have a 300w halogen lamp in it. I have converted it inside and will now just be using the correct 12v power needed. I will also be using a diffuser to make the individual LEDs appear merged together for a softer effect. But as this diffuser will mean less heat will escape, I am just wanting to know a good way of attaching a heat sync to the back of the Aluminium panel.

https://www.amazon.co.uk/dp/B07N2MXP2S/

This heat sync is pretty much exactly the size of the area that the LED strips cover, so should be ideal. I just don't have much knowledge about the methods of attaching it. Are there any particular thermal compounds i should use? I'm not sure if these act like glue and your hold the heat sync in place without needing screws or i would need to drill holes and screw it into the panel?

It might even be the case that the LEDs don't need any of this extra cooling at all and it is just overkill. But I would just like to know how to do this as other LED strips don't get this warm so I feel i should do something to cool these down to extend their life. The LED strip was quite expensive and they are much brighter than others i have got and the colour temperature is far more accurate as well as the CRI. So I want to do what is best to make them last.

Any advice?

Thanks.

What ever you use, read and follow the directions. Whether it's solder or heat sink compound, I've seen that most use them incorrectly; including manufacturers.

I have seen a fair few comments on amazon from reviewers who bought the different types of pastes and that they were surprised with the quantity they reviewer used. I will try to follow what is advised, but I am not totally sure what I am after. I would ideally like what is effectively thermal glue to hold the heat sync to the back of the aluminium plate so it won't need screwing in place. Or would a normal paste compound work if the heat sync got some holes drilled in to attach it by a few screws to the plate? I could do either of these, I just don't know which would be best. And I seem to be finding it hard to come across thermal glue as i don't really know about the stuff.

https://www.amazon.co.uk/dp/B07DWQTPN2/

I am guessing something like this would do the job. What I have yet to understand is how much is to be used over what size area and weather this is enough or not. As it isn't just a tiny component in a PC - the board my LEDs are on is 250mm x 250mm and the heat sync I am wanting is 200mm x 195mm. If this would easily be more than enough quantity wise, then I may as well get it and follow the instructions there. As this isn't glue, do you think it would be ok to hold it on the panel by a screw in each corner if i make the holes?

Thanks.

I've always used this for attaching LED's to heatsinks with great results

https://www.amazon.co.uk/dp/B01N3JWRE3/

This one above does look good as it is effectively glue. I'm just not sure if it would cover the whole area i need. It says there is 5g. I have yet to understand the quantity needed depending on the area you cover. The other thing i am now wondering is thermal tape. This came up in the suggestions on amazon based on what i was viewing. https://www.amazon.co.uk/dp/B07SG416H9/ I am using 12v 5630 LED strips on an aluminium plate. Normally, if the strip was just 1 strip, it wouldn't get the surface so hot, but i have 12 by 12 LEDs on an aluminium panel in a square and and they get it pretty warm. But as they probably won't get anywhere near the temperature of the individual high power LED chips, I wouldn't have thought I would need that much. So would this tape do the job do you think if i cover the area of the heat sync and stick it on with this? Hopefully it will pass the heat through and not get the panel quite as warm and extend the life of the LEDs.

i use arctic silver

You actually want as thin a layer as possible. Even the best thermal compounds are like 100 times less conductive than aluminum. Some are much worse than that. The thermal compound is only there to fill the tiny gaps, as it's way better than air.

From the picture you linked, it looks like that heatsink is far from flat on the back. Even small ripples would be a big problem.

I would think that with such a large area, you'd need to be pretty careful not to get large bubbles trapped between the plates. I'm thinking lots of screws, tightening first in the middle, then working outward, to force any air out. That would make it unnecessary to use a glue.

I think I will buy the heat sync and see how flat the back is. As I said, these LEDs don't usually need a heat sync as they are often used for under cupboard lighting with no heat sync involved. So I still am wondering if such a thorough job needs to be done. It only gets a bit warmer because i have lots of strips in a square on aluminium. I even tried simply sitting an old computer fan heat sync on it that was round and about 12mm x 12mm and that got a lot of the heat through to the heat sync of it without any compound. I don't know how to attach pictures on this forum, but showing the panel I have the LEDs on would give a better idea of the sort of thing that would be ideal. The reason why i thought the thermal tape may be ideal is because it is quite thick. If I use this and some screws, it would likely fill in the small gaps if the back of the heat sync wasn't totally flat. In the description, it also says this: "Professional thermal adhesive tape for mounting heatsinks, chipsets, graphics cards, processors, high power LEDs" If I very neatly cover the entire area of the heat sync, plus use some screws too, do you think this would do the job? https://www.amazon.co.uk/dp/B07SG416H9/ I just feel i wouldn't do a great job with the paste as am not at all familiar with this stuff and how it needs to be applied.

*sink (it's not synchronizing anything)

Also, be very careful with electrically-conductive heat sink compound, so as not to cause electrical shorts.

Haha yes i first looked it up in ebay and spelt it wrong and must have assumed it was right as i saw some being sold spelled like that. I will try to remember it correct now! I have been careful when sticking the LED strips to it and connecting the wires to them. The panel doesn't have either the positive or negative wire contacting it so the heat sink on the back should cause no problems. I will wait until i receive the heat sink and then think about weather compound or thermal tape would be better. I would use screws too with whatever I use but I certainly think I would find it easier to neatly apply the double sided thermal tape than the paste. The tape I have looked at does actually mention it can be used with high power LEDs. So hopefully these strips (just standard 5630) will get cooled down enough using this method.

thermal tape heat conductivity is much lower than thermal glues or pastes, highest one (available and reasonably priced) is arctic silver paste , has almost 9, tapes will get you between 1 and 2.
if you talking about led strips, espasially encapsulated in silicone, do not even bother, it will make little difference, even the surfice you apply it to, dosn't matter much, there is so much thermal resistance inside, they will degrade pretty much same way, no matter what you do, the only thing you can do, is drop voltage to about 10, and it will make much less heat, and it wont be an issue

Thanks for this info. I think I will avoid using tape then. They are LED strips without silicone and they do seem to get the aluminium panel pretty hot. Hot enough that when i had an old PC fan heat sink on it without any compound, it certainly did warm up. I am now thinking the best thing to do will be to use this arctic compound and use plenty of screws to evenly stick the heat sink on. I ordered the heat sink a while ago but it is yet to arrive.

just because it got heat sink hot does not mean much, with those tapes apparently, there is still lots of heat resistance on the strip itself, i tried many different strips, on aluminum angle, on wood cabinet, did not make much difference, all degraded in about same time, in a year they were 1\4 of brightness. only thing that saved them was running them at lower current, but even doing that some strips still degraded even thou they never got hot, i had cool and warm strips mixed in under cabinet lighting, running at 9v (2 strip in series, off an 18v laptop power supply) those tapes ran for a year or two, warm strip was as bright as the first day, cool stip however lost 3\4 or more, both were always cool to touch, ran 24/7.

Interesting hearing your experience. I have received the heat sink just today. Simply by placing the aluminium panel with LED stips upwards (which is what was intended), having the heat sink under this seems to draw an awful lot of heat out of the panel. Leaving it on full brightness before for around 20 minutes would get the panel a little too hot to touch (with no heat sink). Now it is under it still gets warm, but the entire heat sink seems to take most of that. I left it on full brightness for over half an hour, touched the back of the LED panel and it was pretty warm, but nothing like as hot as before. I think I now just need to use the best method to stick the heat sink to the panel to make it efficiently transfer the heat. I am currently thinking about getting this: https://www.amazon.co.uk/dp/B00LT0ZWJE/ I still feel this will be worth doing as i was quite surprised just how much heat having the heat sync there took away from the board the LEDs are on even without any compound. Regarding what I am powering it from, this LED strip is rated at around 12 watts per metre. I have 12 lots of 12 LED strips making a square, so that would likely use between 25 and 30 watts I would say. I have an unused 12v 3.4A power supply which should do the job. I also will be using it with an LED remote which does have a dimmer allowing it to be at 10 different brightness levels. I could perhaps take your advice and have it turned down a step or two. I assume this would do a similar job as dropping the voltage? Thanks.

yes dimmer would do, it does same thing. in any case, when you get to to point of mounting the strip, allow for easy replacement, you most likely will have to replace it in a year or so. that is if you use them 24\7. if not, they can last a while, i still have like 6 years old strips in my closets, glued directly to Sheetrock, running at 12v, they are still as bright as they were before, except for silicone encapsulation getting darker due to age, but I use them several minutes a day. not even everyday.

My intentions for this light is for it to be a daylight equivilent light to replace an old 300w halogen lamp. I will be using the same stand. It is around 6ft high and I will somehow work out a way to fix the panel and heat sink to the old lamp. I have removed the halogen lamp and the old dimmer and will just reuse the cable already built in and wire up the 12v power supply and remote sensor at the bottom. Have already tested that this works and it does so fine. I will just try and do a neater job of it. It will be used as an up lighter and mainly just on dull mornings to make it seem like more daylight is coming in. The colour rendering index of the LED strip I am using is very good compared to most. It is a very clean colour temperature too without that blue tinge. It is around 5500k - 6000k which seems harder to find. It certainly won't be used anywhere close to 24/7 and possibly not much at all in summer. I hope it will last a good few years. The last thing I need to order now will be the compound (linked in my previous post) if you think that would be about the best thing to use between the panel and heat sink before i join it together with nuts and bolts. I think I will use 9 M3 bolts and put one in the centre and then go evenly around the edges too.

Arctic Siilver Epoxy, i also polished my CPU heatsinks and it does improve thermal transfer if only by a small amount.
http://www.arcticsilver.com/arctic_silver_thermal_adhesive.htm

alpg88 said:

just because it got heat sink hot does not mean much, ...

Click to expand...

I disagree. If the heatsink gets hot, it DOES mean that there is significant heat flowing into it. That's heat flowing out of the LEDs that you would not get if they were attached to a thermal insulator like wood or drywall. That will keep them cooler, and that will make them last longer. Will it make them last 20 years? No. But it will help.

All I know is less is more when it comes to this.
Not sure if the same applies to the epoxy, but I would assume so.
Most builders seem to epoxy their LEDs to the pill rather than use thermal grease and screws.

Another mistake people do is fill the pill up with Fujik silicone compound.
In many cases, this actually causes the driver to heat up faster because its actually conducting heat to the driver from the LED itself.
The driver typically does not make anywhere near as much heat as the LED does.