Great news!
The VR16SP4 alpha board test was a success! Although the test could not be completed due to inadequate power supply, the result was already very near it’s peak.
Reflow preparations:
Magnifier application and phone stand is invaluable when working with E21A
Dropping the solder paste. I’m done trying leadfree with E21A. Pb63Sn37 is the best.
Carefully even out the drops to match the pads and then placing the LED, try not to smear the applied paste too much. In this picture I dropped the LED too far away from the target.
Fine tip angled tweezer works best for me. Next to the ceramic tweezer is the press to open tweezer. You’ll need to decrease the tension if you want to use PTO tweezer, E21A’s sides are very soft/fragile.
Ready to go to my “deluxe” gas kitchen stove reflow oven… The final positions will be adjusted later, I tap each LED tried not to move them sideways to make sure the flux wet all pads evenly.
Done, cleaned thouroughly with IPA and toothbrush. Ready for the test
PSU, DMM, Lux meter, Digital thermometer + probe, Test block, big heat pipe fanned cooler, and notepad. Where’s Wally?
I found the heat sink in the last minute, it wasn’t screwed, just sat on top the block using my trusty Moly-graphite bearing grease. It was too late to drill and tap mounting threads, perhaps later.
THE RESULT
New record breaking!! 11,2A at whooping 35,6 watt for such tiny LEDs
The test ended prematurely because my PSU can only supply up to 48 watts. But the curve is already near it’s peak (I predict it should be around 12A). Single E21A can be driven up to 3,1A using my VR16S1 proto board. We assumed 4xE21A in 4P should be able to up to 12A, correct? But when they cramped together in gapless VR16SP4 proto board in earlier test, max current was only 4,8A. Stopped prematurely by the photon cross talks (burnt phosphor’s layer). Now without the photons heating the phosphor layers, the new board can unleash each E21A to their maximum.
Start test block temp was 27,3C, test ended with block temp at 35.3C. I held them at 11,2A for more than 5 minutes while texting and sending pictures to Jensen567. The lux, temperature, and voltage reading stayed the same! Here’s the after test picture, no visible damage, like new. The chipped phosphors caused by the ceramic tweezer when I positioned them in the oven.
Just an Idea to extract more lumens:
If we pot it with something like this 10mm spherical glass lens using optical silicone, more photons can be extracted while making the LEDs cooler.
Looks familiar?
Going for a deep sleep now.