New VirEnce MCPCB for E17/E21/119/144/233U

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.

The cool area around the LEDs proved that lateral heat spreading is minimal with this board

Do note that the cooling setup doesn’t 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.

Nice testing, Jensen! :slight_smile:

(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.)

Interesting test. I always set thermal control to 60C ,according this result 2-2.5A will be best current for that settings.

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. Don’t try to touch the LED using thermocouple probe or you’ll risk burning the phosphors layer.

- Clemence

Update171226: OP updated with VR16SP4 CCT mixing test results (scroll to the lowest pictures)

- Clemence

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 didn’t 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 hadn’t 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.

Thanks Jensen, you’ve been extremely helpful in VirEnce board development and testing
As we discussed earlier last (my) night, there are many factors regarding this wolverine LED. It’s so interesting that the output didn’t change that much (you said the change was too small to be meaningful). I got the same finding but because I cleaned them for the second test, I assumed that was the IPA. I’ll ask Nichia today for surer answer or insights.
Another important thing is: E21A is VERY sensitive to solder quality. My results were on par with your first test (too much solder). I used leadfree solder with worse wetting hence the
Thicker solder joints. Like I reported two days ago, I got so much better result and way easier reflow using cheap 60/40 solder. Your 63/37 is the way to go. For extreme drive current, E21A must be reflowed with 63/37 or better. Lower reflow temp also keeps the solder mask white.

- Clemence

Found this mother next to the board.




FYI: the boards have arrived. Will check it tomorrow in the custom office. :slight_smile:

- Clemence

Testing with 2S2P so… 6 volts’ish in?

Correct Matt
Please check the pictures in below link. I added some configurations diagram there
https://www.virence.com/blank-rwrlr/vr16sp4

- Clemence

If I am looking at the pics correctly, for a 3V setup one needs 2+ and 2- wires?

Unfortunately yes. No space left on this tiny board to create jumper pads without compromising optic’s base or safe side margin.
I’ll make add on secondary jumper board for use on top of it in the near future.

- Clemence

Cool pics! Is that some species of paper wasp?

I think so Looks like its a digger wasp (Sceliphrinae). She didn’t care about anything but her egg safety. Filled two of the M3 screw threads on my testing block.

- Clemence.

Specification:
Changes are highlighted in bold

VR16S1

- MCPCB thickness: 1,65mm ±0,1mm

- Dielectric thickness: 10µm ±3µm

- Dielectric thermal conductivity: 7,5W/MK

- Copper trace: 70µm

- Solder mask thickness: 15µm ±5µm
- Anode - cathode gap: adjustable from 0,5mm down to 0,2mm (was 0,5mm to 0,3mm) by scraping off the masking
- Brighter reflective white solder mask
- Tougher solder mask (untested): prevent yellowing in sustained leadfree 260C environment.
- Copper pads plating: OSP (was ENIG) to get every last bit of thermal performance
- Flat section for V-scoring 15mm maximum (was fully round): mass production consequence

  • Routed MCPCB’s outline, not punched to get the flattest possible bottom.

VR16SP4

- MCPCB thickness: 1,65mm ±0,1mm

- Dielectric thickness: 10µm ±3µm

- Dielectric thermal conductivity: 7,5W/MK
- Copper trace: 35µm (was 70µm) for better reflow process

- Solder mask thickness: 15µm ±5µm
- Anode - cathode gap: 0,2mm (was 0,3mm)
- Final quadtrix footprint: slightly adjustable from 4,4 x 4,4mm to 4,6mm x 4,6mm (was 4,2 x 4,2mm to 4,4 x 4,4mm).
- Brighter reflective white solder mask
- Tougher solder mask (untested): prevent yellowing in sustained leadfree 260C environment.
- Copper pads plating: OSP (was ENIG) to get every last bit of thermal performance
- Flat section for V-scoring 15mm maximum (was fully round): mass production consequence

  • Routed MCPCB’s outline, not punched to get the flattest possible bottom.

- Clemence

Clemence, how hard would be to install vr16s1 with 144 in KF8 ? Seems like perfect host for that combination, except mcpcb size is 20 instead of 16…

You can always run a 16mm PCB in a 20mm spot with no problems. The light should have a centering ring for the reflector and emitter that will ensure the MCPCB is held in the correct spot.

However, jf there is no clamping pressure from the reflector to hold the MCPCB to the host, and instead the host relied on screws to hold the MCPCB down, it is likely you can just use washers on the existing screws to clamp the MCPCB.