Nichia 144A and 229A series: bigger dies, more output, 90CRI included,.......but no thermal slug :-(

Yes indeed. This looks like a drop-in replacement for XHP-50 for the upcoming ZebraLight SC600Fd III Plus.

I think getting those made is a worthy goal. I do understand that a direct thermal path is better technically. But, I haven’t seen proof that Nichia LEDs specifically suffer from NOT having the separate thermal pad. I’m sure it’s impossible to tell, since they don’t make any of their LEDs both ways (with and without DTP pad) for direct comparison. But, what if the emitters that don’t have DTP pads are designed in such a way that heat isn’t the first thing to cause failure? What if removing heat isn’t the bottleneck to performance? I know for Cree LEDs heat is definitely THE issue, but what if for the Nichias it just isn’t?

  1. It’d be nice if it fit on a common Cree footprint so MCPCB’s were easy to come by.
  2. Cree’s probably wouldn’t need a thermal pad at their rated specs either, but because they do we can overdrive them to the levels that make this hobby fun. Likewise I’m sure there is no need for a thermal pad at the Nichia’s rated specs, but it could have been much more fun if there was one. Time/testing will tell.

edit: Late post, Djozz beat me to it.

Direct XML swapping was in my mind…but I didn’t see that the Vf is 6V. It makes the swap more complicated.
Like DavidEF said, it’s more a XHP50 competitor

The 229A is 4.0mm x 4.0mm and ~3V. Not exactly XML size, but could be used for a swap. You’d need to replace (or mod?) the MCPCB anyway, since the Nichia doesn’t have the third pad in the middle for DTP.

There are ways for DTP with custom driver concepts:

a) Reverse the battery so that the body is + and can be electrically connected to LED+.

b) Use a high-side switch, i.e. a P-FET. These typically have a somewhat higher R_DS, but there are very good ones, too. LED- can then electrically connected to body (batt-).

Woa, new NICHIA emitters. Hello High CRI :sunglasses:

Seems like that might lead to the negative side surviving and the positive side turning blue.

So you would use short fat wires from the led into the copper star ?
And heat would go to the star ?
This would work with LEDs that also have a thermal pad. For turbo heat transfer.

Either way there can only be one connection be DTP, otherwise you would still short the led.
Or am I missing some stuff?

We had Bridgelux SM4 but it wasn’t happening…

I’m wondering if the cathode acts as the thermal conduit, therefore must be isolated from ground, unless you want dircect drive.

Which would work better depends on which contact of the LED has better thermal connection to the die. It could end up an advantage, because packages like Cree uses must have internal insulating layers.
Djozz’s sketch would be great if the copper is thick enough.

Why Nichia… Why? :cry:

A makeshift MCPCB shouldn’t be to hard for initial testing. Just use a Cree board whose anode/cathode footprints are close and grind out a little ditch where the thermal pad is with a Dremel, so there is no contact.

Vewy intewesting!

Reminds me of Elmer Fudd hunting wabbits.

If they did a good design and uses the two main contact pads are the thermal conductors then the center pad should not be really needed. ( i guess most of us are used to having the center-pad on Cree emitters to match Noctigon stars, and like to over-drive LEDS to near burn-out. as long as the die, substrate, and two thermal/contact pads are designed well, and we have a good noctigon designed for these LED then where won;t be a problem.

So, if there is a dielectric layer under the electrical traces, how will a Noctigon help? This will be just like all the old Cree boards that have lesser thermal characteristics. The heat being dissipated through the trace pads will still have to go through the dielectric layer and as such, will be slowed down. This is ok if you don’t overclock, not at all conducive to most of us modifying flashlights.

Yeah, DTP stars are pointless if you’re not using the DTP! Best bet would be to make a board like djozz showed, with thick and large copper pours, and use the fancy nano dialectric layer that supposedly has a high thermal conductivity.