Heatsinks for DIY LED lamps

[robincnn]

Looks like your 3070 chip has 3070N written on it.
Seeing mixed results on google. I am not sure if Cree 3070 chips have '3070N' printed on them. May be old chips and CXA were printed with '3070N'.
The heatsink does not cover the entire chip. Chip left hanging in corners. Typical Chinese designs.

I highlighted the original one for you.


Here is my cxa3590 from mouser.com

 

[draz]

I highlighted the original one for you.
View attachment 3530096

Where do I buy those? Looks way better than my COB! Way fuller and rounder.

 

[qwerkus]

Looks like your chip has 3070N written on it.
Seeing mixed results on google. I am not sure if Cree 3070 chips have '3070N' printed on them. May be old chips and CXA were printed with '3070N'. or may be fake once are printed with '3070N'.
The heatsink does not cover the entire chip. Chip left hanging in corners. Typical Chinese designs.

I highlighted the original one for you.
View attachment 3530096

Thank you for the reply. Nah, the heatsink covers the LES surface, which is all that counts. Waiting for more imput about that "3070N"... Though what you post looks a lot like my chips, which would point towards cxa 3070. *sight*. Anyway: I asked the manufacturer for a proof of purchase. No point in more orders there if they don't get the right chip.

 

[littlejacob]

Bonjour
If it is not a cxb 3070 maybe you could ask for a refund!?
You should ask someone who have some to compare...this N look strange!
But try it and if it grow well...who cares!
Have a great day ★

 

[qwerkus]

I doubt I would get any refund. In industrial deals, an error usually means a discount on the next order. If it's a cxa 3070 AD they sent me, there is no big difference anyway. But between cxa Z4 and cxb BB, a rough estimation gives 800-1000Lm @50W difference !

 

[SupraSPL]

You can probably spot a CXB next to a CXA because the glint of the gold traces in the CXB is more prominent while the traces in the CXAs are obscured by the phosphor for some reason.That said, I did come across one CXA3070 that had prominent traces in the new style. So that is not a fool proof method but worth mentioning because I have never seen a "cloudy" CXB.

In addition to that, the traces are in a different pattern from the CXA3070 to CXB3070. Especially noticeable at the bottom. The pic you posted matches the traces in my CXA3070. Notice the trapezoid in the lower center and the three forward slashes on the bottom right. Again, may not always be a foolproof method but worth noting that your COB matches my CXA3070.

The 3070N mark was added to the chips during the CXA3070 runs so some CXAs will have it and some will not. As far as I know, all CXBs have the mark. The N denotes 36V class and R is 72V class.

CXA on left CXB on right

 

[qwerkus]

Thanks a lot for the clarifications SupraSPL. Didn't notice the gold-glint, but I will check again the trace pattern. From What I can spot on your pics, cxb has perpendicular traces on top and bottom, while cxa doesn't have it, am I correct ? Sad though that cree doesn't work with serial numbers like citizen; this makes controlling the chip much easier.

EDIT: Just check all the lamps: they all have this "trapezoid" in the lower middle SupraSPL described. Definitely no random pattern, which means probably the chips are indeed cxa 3070. That would explain the price. Let's see what the manufacturer has to say. For anyone interested, I would strongly advise buying the housings alone, and mount chips + driver yourself. Only way to be 100% sure about the components.

 

[littlejacob]

Bonjour
With a picture it is easy to see the difference between the two cob...
Thanks
Have a great day ★

 

[robincnn]

Thank You @SupraSPL

I had a CXA from mouser since April this year and it never worked. I thought it was static or shipping damage or something. I was not careful when I ordered.
Just saw I says R so it is 72 volt and not 36
It has just been lying around in a toolbox with random parts. Will clean it and fire it up.

@alesh @SupraSPL
Do you think the heatsink base needs to be broad enough just to match LES or does it need to be broad enough to cover the entire ceramic chip. See attached photo. See how corners of chip are not in contact with heatsink. Would love to hear your opinion. Thank You

 

[Shredderthirty]

so i'm just trying to imagine how much power i can ultimately run on this 10" by 36" heatsink. right now i have 200 W on it passively cooled with eight CXB3590s.
I want to put 200W more on it for sure and know it could take that, but the question is how close can you place the CXB3590s to each other? i guess it depends on how many watts are going to each cob.....really i was just bored and imagining trying to put 8 more CXB on this heat sink but that would require to get two rows 3 cxb wide on a 10" wide heatsink to properly space them all out....
I only really planned on putting 14 on this heatsink and running seven cxb/hlg-185-c700 but i've been thinking about cooling it with two large fans like the one @REALSTYLES uses and going with three drivers to power 16 cobs (two with 5cxb and one with 4cxb)

 

[littlejacob]

[QUOTE="robincnn, post: 12020964, member: 74USER=129132]@SupraSPL[/USER]

I had a CXA from mouser since April this year and it never worked. I thought it was static or shipping damage or something. I was not careful when I ordered.
Just saw I says R so it is 72 volt and not 36
It has just been lying around in a toolbox with random parts. Will clean it and fire it up.

@alesh @SupraSPL
Do you think the heatsink base needs to be broad enough just to match LES or does it need to be broad enough to cover the entire ceramic chip. See attached photo. See how corners of chip are not in contact with heatsink. Would love to hear your opinion. Thank You[/QUOTE]
Bonjour
did you try to remove TIM excess?
Or maybe it is not necessary...idk!?
Do you have a thermometer to check the temperature of the cob to be sure?
Have a nice day!

 

[Greengenes707]

You can probably spot a CXB next to a CXA because the glint of the gold traces in the CXB is more prominent while the traces in the CXAs are obscured by the phosphor for some reason.That said, I did come across one CXA3070 that had prominent traces in the new style. So that is not a fool proof method but worth mentioning because I have never seen a "cloudy" CXB.

In addition to that, the traces are in a different pattern from the CXA3070 to CXB3070. Especially noticeable at the bottom. The pic you posted matches the traces in my CXA3070. Notice the trapezoid in the lower center and the three forward slashes on the bottom right. Again, may not always be a foolproof method but worth noting that your COB matches my CXA3070.

The 3070N mark was added to the chips during the CXA3070 runs so some CXAs will have it and some will not. As far as I know, all CXBs have the mark. The N denotes 36V class and R is 72V class.

CXA on left CXB on right
View attachment 3530417

Early CXB's didn;t all have the new marking.

CXA= from blank to 3070N
CXB= from 3070N in black just like the cxa...very few were like this... to B3070N in gold not black...95% of CXB's should be this way.



cxA on lef...cxB on right



Below...is was my first and only cxb's from Kingbrite. They were mixed...some saying just 3070N in black(and were in his stock...possible the first few he ever got)...while the rest...the ones I had to wait 2 weeks to complete my order...were marked B3070N in gold.



I've gone through 1100 cbx3070's from cree(and more in route) and everyone was marked B3070N and B3590N. Even samples. I can definalty say all the logoing issues are long past by now, and all cxb's should be in gold saying "B3070N or B3590N/B3590R.


@robincnn IMO all of the base should be in contact.
Aluminum nitride=~200W/mK vs air=.024W/mK

 

[qwerkus]

Now that was helpful. Thanks alot Greengenes. My chips are written 3070N in grey. Can't say if it was black or gold. Still waiting for a reply from the manufacturer, but from what I pulled here, they are probably cxa. Thank you again guys - really useful stuff here. I'll update when I have more infos. Currently digging into citizen cobs - probably my next choice.
All by side, I mounted the first 3 lamps, and wether it's cxb or not, the light is AWESOME. More plants to follow, probably a lavander and a jasmin. This is going to be a sweet bright winter...

 

[SupraSPL]

Good info thnx GG! Glad to hear they added B designation. Also glad to hear you can recover that 72V CXA Robin.

I had a CXA3070 3K Z4 mounted on a blow through style heatsink with a Copper core. That heatsink gave me the lowest temp droop of any heatsink tested, but the corners were hanging off quite a bit. Judging by that I think it is OK to mount that way but not technically correct way to mount.


@qwerkus do you know of any place that has availability for the larger Citizen COBs?

 

[joseph1026]

Hi Supra! Im having trouble with my build I attached my CREE successfully to my arctic 11 heatsink but I'm afraid to let it run for more then five minutes because I feel its too hot and will burn itself out. Is this possible?

My heatsink stays cool but the surface of the CREE 3070 is in the 200+ degree Fahrenheit zone within four minutes. Am I just dumb and this is actually the normal temps for it to be running at? I measured the temp by putting the tip of a digital meat thermometer on the surface of the LED, the temp continued to rise. After, I removed the LED from the heatsink and figured maybe it is because I did not sand down the heatsink?? Or because there was a thin layer of factory-applied thermal paste plus some of the "Arctic silver 5 high density polysynthetic silver thermal compound" that I purchased and applied myself. Or is there another reason my LED was running so hot? I am using the $13 driver from ebay that you have recommended.

Any advice what my next step is to get this thing running!? I'm so ansy and love the concept!

 

[qwerkus]

Update: Finally got a reply from the manufacturer. It's indeed cxa 3070 bought on some obscure Taobao reseller. They have no idea what bin. I pointed this is not the chip we agreed. Let's see how this thing evolves.
Also, once mounted on the ceiling, the lamps run much hotter. I have no precise measure yet, but I'd say 50-60°C after a few hours. Still acceptable for a passive setup, but not optimal for chips life. Considering lowering the power input to 45W.

@SupraSPL: Wrote at least to 50 different asian resellers, and never got a good offer. Best place for CITIZEN chips seems to be tme.eu or cdiweb in the us: http://www.cdiweb.com/ProductSearch.aspx?Refinement=&No=0&Nrpp=25&reset=1&Nr=p_portal_id:1&Ntt=citiled#.VjHHjpf5K90

 

[qwerkus]

Hi Supra! Im having trouble with my build I attached my CREE successfully to my arctic 11 heatsink but I'm afraid to let it run for more then five minutes because I feel its too hot and will burn itself out. Is this possible?

My heatsink stays cool but the surface of the CREE 3070 is in the 200+ degree Fahrenheit zone within four minutes. Am I just dumb and this is actually the normal temps for it to be running at? I measured the temp by putting the tip of a digital meat thermometer on the surface of the LED, the temp continued to rise. After, I removed the LED from the heatsink and figured maybe it is because I did not sand down the heatsink?? Or because there was a thin layer of factory-applied thermal paste plus some of the "Arctic silver 5 high density polysynthetic silver thermal compound" that I purchased and applied myself. Or is there another reason my LED was running so hot? I am using the $13 driver from ebay that you have recommended.

Any advice what my next step is to get this thing running!? I'm so ansy and love the concept!

I'm myself fairly new to the LED world, but I happen to bring a lot of experience from the DIY cpu cooling world. A few thumb rules I would advise:

1. Do not touch the surface of the LES. Never. Especially not with a Thermometer. On cree chip, there is a Temperature measure spot on the top.
2. Never mix 2 different Thermal paste. Clean up the old one first with some alcohol before applying the new paste.
3. Sanding helps to cool down, but in my experience never more than a few degrees
4. Don't think it's the driver. Looks more like a mounting/setup problem. If both your Heatsink and your Chip start to get burning hot, than it's probably a too strong/wrong driver.

 

[SupraSPL]

It is critical that the COB have good contact with the heatsink surface. But as long as that is in place you should be all set. The meat thermometer in front of the LES will get much hotter than the actual LES temp because of the stream of photons hitting it and converting. Normally I check the heatsink temp between the fins behind the COB if possible to get an idea how the unit is performing. The CPU cooler heatsink will stay relatively cool even with the COB at 50W and even with the fan running at 5V.

If you are concerned about the thermal interface, you can check the temp droop with a lux meter and a watt meter. Or you can take the COB off the heatsink to inspect and then redo it with new paste.

 

[robincnn]

@joseph1026 Good to stay away from LES yellow area. If you poke it with ur thermometer than you will break the connections within LES. I posted a thread few days back for LES connection damage.
I put a themocouple near LES of vero 29 at 2.1 amps and it was near 120C or 150C. So your 200F seems normal. It gets hot due to light as Supra said. Read the datasheet of your cob and find the case temperature measuring point. Measure themperature only there.

 

[SupraSPL]

In my experience the light can interfere with the case temp measurement point as well. But maybe others will have more luck with it than I did.