Future development of the maximum luminance of LEDs

Interesting, the package does look a bit weird though!
One difference: the Stanley has two bond wires.

Luminus now has a new LED on the site, the XP-G2 sized brother of the SST-40, the SST-20 (datasheet).

Features:

  • Thermal resistance: 3.5°C/W (XP-G2: 4°C/W, CSLPM1.TG: 2.6°C/W)
  • two different solder profiles:
  • => A120: XP solder profile with neutral center solder pad
  • => B120: smaller Osram (Black Flat, Square etc.) solder profile with neutral center solder pad
  • rated up to 3A
  • square die (not retangular)
  • brightness at 1.5A: up to 10.7% higher compared to XP-G2 S4, average might be closer to S3

Maybe 220-230cd/mm^2 are possible? Benefits here are that the new Luminus LEDs seem to be chaeap and easy to obtain. They also seem to still have a cool-white tint after de-doming.

Love those bond wires… :person_facepalming:

I wouldn’t worry about those right now. The SST-40 goes up to 9A and also had just two. It’s possible that they use the same ones in this LED.

And, though not the scope of this thread, the SST-20 comes with some warm 95 CRI versions.

Not too concerned with current capabilities, those long bond wires make it very hard for a clean de-dome. They tend to break when the dome releases during the chemical de-doming process. I went thru over 30 SST-40’s. Vinh gave up on them too, he just shaves them now.

I wish a purely chemical dedome would be easier with these, but I’m not holding my breath. I’ve had good luck with a combination of shaving / slicing / chemical dedome. Considerably more work, but still good results.


click for larger image

SST-20 L2 6500K is available on kaidomain for $3.19.

prophotonix never answered.

I found 2 more companies which may be willing to make a batch of custom LEDs:

At least the latter has the necessary expertise:

I haven’t mailed them, if one wants to do it - just do it.

What is the die size of old XP-G2?
Here I see 2.16 mm².
In the CRX thread 1.66 mm² for old and 2.18 mm² for new…

200 cd/mm² seems semi-consistent with the smaller number.

1.66mm^2 for the first version from 2012-2014

Then koef3 got about 216 cd/mm²

One thing to note here is that the way of measuring the die size is not perfectly accurate. It is usually done by carefully taking a picture and then counting pixels.

What about this LED (don’t know if this LED is already discussed)?
http://www.nichia.co.jp/en/product/led_product_data.html?type='NJ2W270A-Y7'

I noticed it a few months ago, but didn’t see any big benefits. The rectangular shape of the die is definitely a downside.

They do state the luminance!

Die size: 0.93mm^2
Real thermal resistance: typ 4.1cd/mm^2
Luminance at 700mA: avg 110cd/mm^2

Edit:
The Black Flat is 20% larger, but only does 66cd/mm^2 at 700mA. So the Nichia might actually be really good if one can live with the die shape! Thanks Schoki!

Edit2:
The weird thing is that it’s a 6V LED! This makes it easier to drive the LED to its max in single cell lights, there are good boost drivers available.

I wonder how far apart the two dies are. This could ruin the beam with smo reflectors.

OK, so let’s consider the dies separately, so we can compare with Blackie a bit better.
Half-Nichia:
.465 mm² die. 110 cd / mm² at 1.5 A/mm² and 5 W/mm².
Blackie:
1.122 mm² die. 110 cd / mm² at 1.25 A/mm² and 3.85 W/mm².

Nichia has a bit better thermal resistance, but it doesn’t seem to be enough.
Also, its LES is significantly higher than die size in case of Nichia.
So probably not too good….

I think we really just need to wait for the new Osrams.

I need some clarification here: candela is Lumens/Steradian, so the value changes with the amount of dies I place next to each other?

Yeah, I’m keeping tabs on octopart, hopefully soon they will be available in individual units.

Luminance is candela per square millimeter of die area. This means it’s independent of the angle from which you are looking at the LED. The luminance determines the throw when the LED is combined with a given reflector or optic. The area of the lit up reflector as seen from the position of the hotspot in some distance mutiplied by the luminance determines the Candela (which leads to throw). This means that two LEDs with two reflectors will double the Candela (which leads to throw). A larger LED with the same luminance as a smaller one will not increase throw with a reflector, only the hotspot gets larger.