I’m sure I’m not the only one curious about how this board performed compared to copper DTP. Am I correct?
Check the OP 
- Clemence
I was, at least.
And they hold up very well! There’s no real need for a DTP board with these. If this technology is getting a bit cheaper these type of boards can be a solution (for flashlight use) for leds without neutral thermal pads.
Well…some people in HQ “forced” me to do it. Now, I’m thankful to them. These are not cheap at the moment, but it will be.
I’m thinking single sided driver boards can benefits from this technology.
- Clemence
Mini review of the VR16SP4 and E21A LEDs.
The quality of the board is very good, nice thick copper tracks and well setup to be very versatile. Also has a nice thin reflective white solder mask, which allows a thin solder layer and reflects most light which hits it. Assembly with E21A is fairly difficult though, and is not for the faint of heart.
My first attempt. I put too much paste on the top left which resulted in a small solder ball popping up in the middle of the 4 during reflow. Thankfully it came right off. Second picture is after a cleaning with IPA and a cotton swab to remove any flux residue. All emitters functional! Setup is 2S2P for 6V type.
After running at 2.8A for about an hour on the worst heatsink ever. Can see some slight browning of the phosphor. Still running great though. I put them on a much better heatsink at 2.1A today for about an hour. I don’t have a photo but the brown seems to have actually gone away somewhat.
Seriously, worst heatsink ever, random piece of leftover phosphor bronze sheet. That colored spot is the back of where the MCPCB sat. To be fair I only intended to run it for a few minutes but got sidetracked. The new heatsink setup is MUCH better. Thankfully the victims of my crime were just R70 emitters Clemence gave me to practice with.
My second attempt went much better, almost perfect alignment and no real cleanup needed. Still gave it a bit of a wipe with IPA just to be safe. All emitters light again. As is I really like these boards and plan to buy more of them. The changes for the production version should be beneficial for assembly and emitter longevity.
Once the production versions come into stock I will begin to experiment with tint mixing using these boards. I have a light I plan to build with 50mm quad optics using 4 quad E21A boards, so 16 emitters in total, and as many tints as I can get by the time I build it.
I will do a review for VR16S1 tomorrow. A little note for both boards though. These boards rely on thick copper with as much surface area as possible being on top of the nano ceramic base layer. This gives them the great thermal performance they have. However, this thermal transfer also means soldering leads is very difficult. I would recommend a nice powerful iron, especially if you want to attempt to solder it in a host because the board really sucks the heat away from the pads. Either that or pre-heat the whole thing in an oven to near reflow temps.
Thanks for the review Kyle. Actually, in this case, the copper spread has little effect to cool the LED. The low thermal resistance of the dielectric dominates most of the thermal transfer via through thickness direction. Lateral heat spreading only plays significant role up to 1,75 mm radius from the heat source point. This means the same board performance can be achieved using board size as small as only 3,25 mm larger than the LED used.
Thick copper foil will, unlike traditional thoughts, increase through thickness thermal resistance and lower the board performance. Sounds like nonsense but the factory lab test proved this. To give you better perspective, normal high performance MCPCB use 0,4 - 11 W/MK, 100 - 200um (0,1 - 0,2mm) thick dielectric. This board use 7,5 W/MK, 15um (0,015mm) dielectric. At this scale level, additional 1 Oz. copper (35um or 0,035mm) is huge. Long time ago, Barkuti pointed us (here and in CPF) about nano ceramic made in China boards he found on AE. Most people especially in CPF, mocked him for using the nano ceramic words (while in fact it’s the wording used by the manufacturer no him). He insisted on the potential performance of the boards, and I remember many people shoo-ed him. Now, the same technology approach is what I’m using. 
The decision to use 2 Oz. Copper foil was to increase current carrying capacity while keeping the heat generated as low as possible. This is useless for VR16SP4 since the LED max current is only 3A - limited by the phosphor temperature. VR16S1 gains benefit from 2 Oz. Copper because the compatible LEDs that can be used on the board have much higher limit.
Thick copper foil also makes reflow harder. In most case some of the paste will fill the gap between LED’s pads. This is especially problematic with lead-free solder with worse wetting capability compared to leaded solder. Less wetting equal less molten solder adhesion and more chance to solder bridging.
The VR16SP4 rev.2 will have 0,4mm gaps between LEDS, 1 Oz. copper, and SMD (Solder Mask Defined) pads. Current prototype is using hybrid SMD and NSMD. Don’t worry about the increased gaps would creates ugly beam under tight optics. With current gapless design it’s ugly already, much like XHP50 beam profile. VR16SP4 is never designed for tight optics anyways.
- Clemence
I’ve just caught up with your testing here Clemence. Thanks for taking the time to do it. Its all good useful info. :+1:
You are most welcome Ma’am Sir 
- Clemence
MRsDNF is not a Ma'am. 
What!?
That’s what I’m assuming all these time. I asked Djozz about if there’s female member other than MrsDNF (I guessed by the name there must be MrDNF somewhere). Then he replied there’s TK and some hidden female members too. But he didn’t correct me about MrsDNF, so I thought it’s true.
Okay will fix that. I’m sorry MrDNF. 
- Clemence
LOL, I was not aware that I spread a rumour that MRsDNF is a female.
But in Steve’s case there’s pictures of him around on BLF.
But then again, you never know on the internet so he may still be a woman but then a very manly looking one.
I think I’m in love. :heart_eyes:
It difficult for me too) In Russian language endings of verbs are different for male and female so you always know gender of interlocutor.
By the way recently I installed vr16S1 in flashlight , I also have the same flashlight with copper noDTP 144A star from Djozz. While it heat up to 60C(on host) luminosity drop are 4% for vr16s1 and 6% for copper. Test not very strict but…
Also white solder mask looks much better under tir optics.
Thank you clemence for great MCPCB!
Oh no…. 
The difference will be greater as you increase the current. For anything below 2A this board is overkill.
- Clemence
It is the only one mcpcb available for 144A I know)
Yeah, internet can be very deceiving these days. Who knows…. :laughing:
Here’s the root of all my misleaded assumption: [GB ended,discussion only] CRI > 80+ NICHIA 2000K-6500K [E21A/219B/219C/319A/144A/757GT-F1(Optisolis)] - #787 by clemence
- Clemence
As promised here is the mini review of the VR16S1 board for 144A and other 2 pad emitters.
Like the VR16SP4, the VR16S1 is a high quality MCPCB with a nice reflective white finish. The pads are setup specifically for the Nichia 144A, but can also work with other 2 pad LEDs. The board is made with the same nano-ceramic technology which allows great thermal performance without needing a DTP board.
My first attempt using my standard lazy reflow method. Since the PCB is aluminum and solder won’t stick, I just wet my iron tip then hold it on the bottom of the board, then melt a bunch of solder onto the pads. After this I add some flux paste to the emitter bottom, and heat to reflow temps with the iron again. Once I see the emitter move into position I whack it on the top to shoot out all the excess solder. After that it’s just a matter of cleaning up all the flux. Overall this method worked as well as it does for any standard emitter and the emitter self aligned on the pads well.
Second attempt, this time actually using solder paste, too much solder paste at that. Standard paste procedure, apply paste, set part on paste, heat with hot air until reflow. In this case I also whacked the LED on the top to eject the excess solder since I used way too much paste. After that just a simple cleaning with IPA.
Third attempt, again with solder paste, but a reasonable amount this time. Followed the same reflow procedure as the 2nd attempt, but no whack needed as there was not a bunch of extra paste this time.
The VR16S1 is a great board for 144A and finally gives cree a useful competitor for XHP50 series in flashlights.
Overall I am very satisfied with both boards. The main drawbacks are the hard to solder wire pads, (which is only because the thermal performance is so good), and the somewhat fragile solder mask, but that’s done to get a better solder joint, which is a worthwhile tradeoff I think. I look forward to both of these being regular items in the shop.
Thanks for the review Kyle, and for various reflow methods. To solder the lead wire after the board installed in the host, I use Hakko Presto 20 - 130 watt solder iron: http://www.hakko.com/english/products/hakko_presto.html
But I changed the regular tip to long fine tip.
Rev.2 boards delivery scheduled in mid January 2018. Too many holidays disrupting the production in December.
- Clemence
So, if I have followed correctly the quad E21A would really like to be drive at around 3A total in parallel config? That is a very interesting board and concept, basically 4 leds in an XM footprint with very high CRI. I have been using the R9080 with the 219’s and would be interested in these little guys now.
The rev. 2 should be able to be driven more than 3A. My optimistic goal is 6A in 4p or 3A in 2s2p or 1,5A in 4s . Let’s keep fingers crossed.
The prototype was only 4,2mm x 4,2mm, the rev.2 will be 4,6mm x 4,6mm and much easier to reflow manually.
- Clemence