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 butā¦
Also white solder mask looks much better under tir optics.
Thank you clemence for great MCPCB!
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 wonāt 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 itās 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 thatās 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.
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 219ās 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 . Letās 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.
Jensen567 just finished IR test the VR16SP4 board with results very much line up to my observations. Wait until he posted the results.
Well done Jensen567, BIG thanks!
Here are some images from thermal testing on the VR16SP4 board using a 2S2P emitter setup. Each image represents a 0.5A current step, I started at 0A and went up to 4A. The final image is taken at 3.8A and shows that the phosphors have roughly hit their maximum of 150C at this point. Room temperature was approximately 22C during testing.
One thing to note is that the top left emitter specifically and the left side in general seem to be the hottest. This could be due to a variety of factors. Not enough solder, too much solder, imperfect alignment, or some slight phosphor damage from a previous test that overheated.
Test Setup, large 120mm fan cooled heatsink.
0A
0.5A
1A
1.5A
2A
2.5A
3A
3.5A
4A
3.8A
Chart
The slope of the line on this chart is right around 33C per Amp (less down low, more up top, not actually a linear function, but close for this range), with the Y-axis intercept being the environmental temperature. Using that info we can calculate what the rough maximum current will be for a given environmental temperature, assuming good heatsinking.
Do note that the cooling setup doesnāt reflect flashlight use. In a flashlight, the LED shelf in not cooled in the centre but only one the sides. Heat has to travel to the sides somehow and it seems to me that MCPCB is a good path. Certainly not all heat will travel this way, but nevertheless I think it should be heated as a whole.
You are correct that in a flashlight we will see more heat in the MCPCB, but that will mainly be due to the entire head heating up since flashlights are (usually) not actively cooled. The thermal junction between MCPCB and heatsink/head should relatively even out any heat spread through the MCPCB regardless of the heatsink below it though, so the actual gradient should be similar, but board temps overall will be higher in a flashlight.
Ultimately in this test I wanted to see the limits of the emitter and MCPCB though, not the heatsink below it, as in flashlight use the heatsink varies greatly from host to host.
(I do not think that in a flashlight, with a 1.5mm copper boards and even a shelf under it, the sitiuation would be much different from this, perhaps overal less heatsinking but not spatially different.)
Now we know when to stop increasing current. 135C is the safe max BLF limit and 150C is the absolute peak max. Beyond 150C the output will drop sharply and start to smoke anytime. Laser guided temperature meter should be affordable to most people while TI camera is the best. Donāt try to touch the LED using thermocouple probe or youāll risk burning the phosphors layer.
New test of E21A quadtrix. My second reflow attempt this time. Change to the test setup included an addition of a lux meter, though not a great one and not mounted well, but it did provide some insight into peak output.
Below is an image compiled by Clemence showing all of the IR images taken in the test, as well as some plots of the data taken. Emitter setup was 2S2P. Please note with the Lux data that I did not turn off the room lighting, so it started out at non-zero. The setup also means that the number could be changed quite a bit just by moving around the room, so they are very approximate.
On this test I went beyond the 150C phosphor temp based on lux meter readings. Peak output occurred at 5.5A!
Phosphor temps were imaged up to 5A, at 5.5A I unfortunately messed up and didnāt save an image, but phosphor temps were bouncing around the 200C mark. At 6A I did not take an image as I saw the temps at 210 and rising and the lux meter was starting to drop fast, so the test was immediately shut down.
This was the result of that 6A run, slightly browned edges right where the two hot spots are between the emitters. If i hadnāt shut it down quickly I predict it would have ended up like the emitters Clemence shows in the 1st post. This also proves the photon absorption, and I am fairly confident the Rev.2 boards with larger gaps between emitters will be capable of even higher output.
After this I tested a hypothesis from an observation of my last test. I re-ran the emitter at 4A for about 5 minutes, and then ran the full sweep from 0.5A to 4A again, with only about 30s per step, just to check Lux. Lux was basically unchanged, I could move my arm and change the number more. Visually the browning is now gone too. Not sure what causes this phenomena, but Clemence has seen the original images with their attached timestamp data and can verify.
It will be interesting to see if more people push these LEDs and also observe this strange healing effect of the phosphors. Will also be interesting to see how the new gapped MCPCB layout changes performance and the hot spots.