Nichia E17A/E21A series (April 19th: updated with output tests in the OP)

I want one! Who needs a separate thermal pad? If Nichia believes it don’t need it, or there is no benefit to it, who are we to say otherwise? So, when does the GB start?

Edit: Luminous Flux of the E21A @700mA roughly compares to XP-G2 S3 or XM-L2 T6. Package size is 2.1mm x 2.1mm for the Nichia, 3.45mm x 3.45mm for XP-G2 and 5.0mm x 5.0mm for XM-L2. So, did I say I want one? Maybe I want a few dozen! O:-)

These new Nichias look very promising for tiny pocket throwers.
How is the color rendering of these pipsqueaks?

Looks like they come in two flavors - 70CRI and 80CRI

Thanks for finding out the flux comparisons!

The package comparison is not really fair, for flux density (which is the relevant factor for throw) you need to compare die size: the XP-G2 die size is 1.5x1.5mm, compared to 2.1x2.1mm for the E21A. That suggests that the XP-G2 still wins, even though Nichia claims that high flux density. But what will happen at high current on a copper board is the question…

Since there isn’t a separate thermal pad, I don’t think a copper board will have any advantage over an aluminum board. Since the heat transfer will be going through one, or both, (I’m assuming it will be the cathode) contact pads, there will be a dielectric layer the heat will have to go through.
Sure, you could shift the emitter so part of the cathode is making contact with the DTP, but then you will be dealing with permanent direct drive.

Yeah, I knew that, but I couldn’t find anywhere that says what the die size is. If you can link a source for me, that’d be great! And of course, the XP-G2 definitely wins by a long shot, because that wasn’t even the highest binned XP-G2! :wink:

Although for flux density, only the die size counts, package size does matter in other ways. I’d still like to play around with some of these Nichias. Really, if you think about it, it would seem that Cree and Nichia had some similar advances. Cree starts making flat emitter packages from existing high output dies, and also squeezing dies onto smaller packages. Then, Nichia combines those two in a “chip IS the package” deal with a flat profile. If Cree wanted to, they could easily make a direct competitor to the Nichia E17A and E21A series. They’re already really close with the packaging, and way ahead in flux density!

A copper board should still give a little advantage, because it is copper. I agree that DTP isn’t even a consideration, but copper should do better than aluminum anyway, I’d expect.

If you mount four E17A leds on a XP-Noctigon, you can have all the plus-sides of the leds on the DTP-pad and thus the flashlight body, the led-minus’s will be on the two ledwire-pads combined. Then use a reversed battery and direct the minus of the battery to the ground of your driver, making sure that the led-side ground ring of the driver does not touch the body, while the batt+ pad does make contact with the body. You can rebuild the driver for this by isolating the led-side ground ring of the driver with Kapton-tape, and boring out (just slightly, from the battery side of the driver) all the via’s going to the other side to make them loose all contact to the other side, then make two holes and wire the old batt+pad to the led-side ground ring, and the old batt-minus pad to the led-side+. Are we still there? ;)

I guess I should assume you were thinking about this.

Umm, I don’t know much about drivers, but would there be a way you could re-work the driver to interrupt power to the LED+ instead of the LED- so that none of that drillin’ and choppin’ are necessary? Or is driver design such that your drillin’ and choppin’ IS the easy way? Or is it that the components all work on the negative side, so switching positive is basically impossible?

Good gosh man…so you’re basically saying that we could all be running around with 12 emitter Convoy S2+s on a triple XP board?

Uhm, I guess so… :sunglasses:

Say you can overdrive the E17A to 1500mA on a XP-Noctigon, the output (extrapolated from the Nichia datasheet graph) could be 560 lumen, times 12 is 6720 lumen, with losses 5000 lumen out the front.

… for a brief moment because you are running your S2+ at 18 amps/63W O:-)

w00t!
…and there goes the battery tube - melting away… }:slight_smile:

Thanks for showing off these LED’s Djozz. I can think of a couple fancy ways to design a special star for this led.

One approach is to use a dielectric PVD coating to electrically isolate the star from the rest of the light while retaining optimal thermal transfer. Imagine a two piece star, split down the center, with the dielectric PVD coating on the bottom and sides of the stars semicircle halves. Butt these together. The gap at the center would be practically non existent but it could be shimmed ~.001” or more and that gap filled with high temp thermal epoxy. The gap between the halves would widen and bevel after it left the area under the LED, taking on more thermal epoxy to more strongly keep the star together as one piece.

A less elegant method would be to take an aluminum disc (or the head of a light) and machine two pockets across it, with only a .002” wide divider in the center between them. Anodize the aluminum, then embed a thick, machined copper strip into each of the pockets. A small amount of high temperature thermal epoxy would be necessary under the copper strips. Or, omitting the.002” aluminum divider, (so one contiguous pocket) the copper strips could be shimmed in the middle when “set” into the pockets. Filling the shim gap would be high temp epoxy. The gap could be made ~.001” or wider with this method.

Interesting. Very nice find, djozz!

Hoop, that makes me think of a board I made for a Luxeon Z once: LuxeonZ, the making of a copper board, and testing
It still works but upon heating up, after a few minutes something deforms and shorts, when cooled down it works again. I think I made the AAA insulating layer too thin.

You could use the DTP pad for probably the cathode, and use enough thermal compound between the star and pill that there is no electrical pathway. It’s not ideal, but better than permanent DD, with a little better thermal characteristics.

It would be nice is someone made a cooper MCPCB with its footprint and a thin or heat conducting insulation layer. The Cree LEDs must have an insulating layer in them, but apparently it conducts heat better than the insulating layers of existing MCPCBs do.

I suppose by PVD you mean physical vapor deposition, that is the relevant meaning in Wikipedia. That and anodization both sound like good ways to make thermally conducting electrical insulation layers. I am thinking thin film diamond, but that is too expensive.

I think a thin sheet of something would be easier to control than a thermal epoxy layer under the star. That would really be the best way, because the area of the insulator conducting the heat is much bigger.

How about the mica insulators used for TO-3 packages on heatsinks in through hole stuff? I dont remember how big a TO-3 is exactly, but i think it would be enough to fit under most stars in this small a light.