Thank you for this test and the well presented results even a non-tech person like me can understand easily.
I got one question, how good/bad will a 20mm noctigon board perform in comparison to the sinkpads ?
About the same. From our members’ tests, pretty sure we can establish now that the limiting factor is almost always the dielectric layer. Once that factor is taken out, even aluminium base gives performance not too far from Noctigon/Sinkpad.
Thank you Sir ! :face_with_monocle:
According to these high end tests there basically no difference.
There is a new MCPCB with a Diamond like dielectric structure. The dielectric functions like graphite which is used by high end fixtures manufacturers as a thermal pad, in that it spreads heat both vertically and horizontally and can provide performance of copper PCB, in a ALU PCB (cheaper)
do you have a link?
That is good news for the emitters without electrically neutral thermal path, like the Oslons :-)
Interesting results, thanks for the detailed tests.
I think where this is most valuable is in modifying those oddball size stars that Sinkpad and Noctigon don't have, 25mm in the Aleto 26650, 32mm in (I forget what). Maybe even triplet/quad boards?
Huge difference between direct heat path and one with the dielectric layer though
the basic details are below. a comparative guide between normal dielectric and the DLC
email me if you want details
Excellent djozz. Thank you.
nice graphic
I find these are helpful too
thanks
Looks useful. I hope you'll send samples to one of our members for review. Relic38 has done some nice reviews. Hopefully he'll be up for testing this too.
A couple questions though.
How can I tell from your webpage if a mcpcb is using DLC? Will a triple XM-L board be made?
Looks very promising but, as usual in marketing, the 'old' type board is drawn to perform worse than in reality; the heat when entering the aluminium core of the board will go circular in all directions, not just downward, as the drawing suggests.
In any case, I think the major bottleneck was already overcome by the direct-bond-to-copper-boards, I do not expect a performance improvement as high as when Sinkpad boards entered the market. But the electrical insulation between thermal pad and core is a really useful feature!
Exactly!
All Copper boards can be enhanced to distribute heat better (not really needed), like all AL normal boards have the thermal trace as wide as the boards. For some reason on direct thermal path they decided not to them like that.
I do not see them actually work better than direct thermal pad boards which clearly cannot take advantage of the 390W/m.k of the cooper when you can see Aluminum boards rated at 135W/m.K performing as the 390W/m.K copper boards.
So what I mean that wide spread can be done with normal copper direct thermal path, especially for single LEDs on 20mm.
djozz - Excellent info, great job on this! Lots of time and some cost I'm sure...
Question - didn't see it mentioned, what was the time lapse on your measurements? For example, was it pretty much instant once the amps was set to the point of reading the lux meter? Wondering if under-lying these stats is the dimension of time - what's the instant reading vs. 10/30/60 seconds of runtime. Of course it would take long collecting all the data pts, but would be interesting to know if the copper MCPCB's show any advantage over aluminum.
The reality is copper as a base substrate has better thermal performance than ALU. The issue has always been the dielectrics which are generally high in fibreglass are the issue and direct thermal pads make a big difference. This is more an exercise in replacing the dielectric to make ALU boards a better performer relative to copper as ALU is a lower cost product. I have some initial samples of a multi led XML PCB, happy to donate for test?
The costs were mainly my new power supply. I bought it to do these kind of measurements, and it performs really well. With my old one I could not have done these kind of tests, it does not go over 7 amps, and setting a current is a pain. The new one adjusts really easy and goes up to 20A. I prepared some things beforehand (like initial testing out the power supply and test-leads, and removing the dielectric layer on one of the boards). But the actual tests were done in one session lasting an evening and part of the night.
The time lapse was mentioned, but not in the OP (should have been there). I started each test at 0.5A, going up 0,5A each time and recording voltage and lux, up to 7A. After each rise I waited 10 seconds and then recorded V and lux, I think the led was at each current for about 25 seconds total, but the starting point for each new current of course was only 0.5A less. Indeed if I had waited much longer to let it settle more, the whole test-series would taken more time than I was happy to spend on it (my hobby is squeezed in between work and family, I have to admit both suffer from it, but I just need to have a hobby), but looking at the luxmeter during the tests I never (also not at 7 amps) saw fast declining numbers signifying an unstable siuation, (typical example: when a reading at 10 seconds was 702 lux, at 20 seconds it would be 700, and that did not worry me).