How Reliable are Bin Codes?

Every emitter on a roll of 100 is given the same bin code.
But those emitters won't all have the same brightness or tint or forward voltage. But how much variation is common?

It seems like people in this forum think that the bin code is completely reliable, whereas this unreliability is the root of the commonly used, but sometimes misunderstood phrase "Luxeon lottery".

Maybe someone who has experience with rolls of Luxeons can tell us how much variation they expect to find within a roll.

I'd say they're very reliable. Why would they use them if they weren't? The lottery is just a question of which bin you end up with in your light.

But I'm a newb and could more than likely be completely wrong. I'll sit back and wait for the pros hehe.

Do a search and find Mr Bulk's discussion of BIN codes from about a year ago. They are extremely unreliable and that is why he grades each led and doesn't depend upon the roll BIN.

Well then, I'm a moron /ubbthreads/images/graemlins/smile.gif

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D-LIGHT said:
Do a search and find Mr Bulk's discussion of BIN codes from about a year ago. They are extremely unreliable and that is why he grades each led and doesn't depend upon the roll BIN.

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Thanks. I didn't know it was that bad.

Be careful what conclusions you draw based only on your emitter's bin code. It may not be what it says it is.

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Robban said:
I'll sit back and wait for the pros hehe.

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That's why I started this thread.
Many people haven't been exposed to this information.
Remember, they are binning the entire ROLL at once, not the individual emitters.

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Robban said:
The lottery is just a question of which bin you end up with in your light.

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If a manufacturer is using a wide range of bin codes in the same model of their light, with some emitters being tinted and dim, and others being white and bright, then they are just being dishonest. Then it becomes a "Q3" lottery (for instance), not a Luxeon lottery.

I strongly suspect that emitters are individually-binned prior to reeling or "starring." I also suspect this is a fully-automated process with associated calibrations/tolerances. Each LED is binned for 3 characteristics and the bins seem to me to be relatively wide. IMO, The sum of the within-bin variations add up to the majority of the differences frequently observed between a pair of identically-binned LS's. /ubbthreads/images/graemlins/icon3.gif

Larry

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LightScene said:
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Robban said:
I'll sit back and wait for the pros hehe.

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That's why I started this thread.
Many people haven't been exposed to this information.
Remember, they are binning the entire ROLL at once, not the individual emitters.

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Actually your statement is incorrect, at least for Lumileds, the manufacturer of Luxeon LEDs. Each individual LED is tested and categorized by bin.

However, if you will do a little searching here on CPF, you can find other discussions that outlined exactly how much latitude Lumileds allows for the various bin parameters, i.e., Vf, color tint, and lumen output.

This isn't something that Lumileds trys to keep under a rug; they specifically outline the variances to designers and try to get them to understand the possible ranges and how that will affect the final product.

What has been happening is that Lumileds now seems capable of producing more of the "good" bins than in years past.

HTTH.

Yeah, I'm pretty sure that Larry's "suspicions" are on the money. The loose emitters are tested and sorted, and then "reeled." The Lux Lottery refers to having a Lux of a known bin, and NOT having it perform to the specs one would expect. Those of us who see lots of these things have seen many that just don't fit the bin they happen to be marked with. It drives the builders nuts and it can drive the consumer nuts.

And then to top it all off, Future won't even sell us the bins we request - for ANY price! I may never understand their "marketing."

I have two TWOJ Lux III LEDs and they are in no way the same tint... One is perfectly white while the other has a more icy bluish-green tint...

Whatever their means of binning, I think Lumiled's variations are more than enough for a picky eye to notice.

They cannot (I don't think) be using an actual integrating sphere for flux measurement on line. More likely, a simple Lux meter, back-calabratable to a lab sphere and based on a bunch of "average" data. The tolerance stack for variations in dome epoxy lot, dome mold cavity-to-cavity dimentional variations, and dome bonding variations will effect how "Lambertian" each LED is, and the resulting Lux. I clueless as to the metrology associated with colorimetry. And, of course, those pogos used for Vf measurement never get tired. /ubbthreads/images/graemlins/grin.gif

Larry

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Darell said:
The Lux Lottery refers to having a Lux of a known bin, and NOT having it perform to the specs

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Don't worry, the Vf shifts also.

There is a thread in the electronics forum on this.

I've seen the Luxeons shift outside of their spec'd bin with time, even with much more than adequate heatsinking.

They are squirrely little critters, thats for sure.

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They cannot (I don't think) be using an actual integrating sphere for flux measurement on line.


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Actually, (surprisingly) they do. A 6" integrating sphere is used for measuring lumens. The test procedure is outlined in application brief AB08, on page 13.

Although my first idea was the same as yours - that they use a lux meter at some calibrated distance and use a simple conversion. But they go all out and use an integrating sphere.

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NewBie said:
Don't worry, the Vf shifts also.

There is a thread in the electronics forum on this.

I've seen the Luxeons shift outside of their spec'd bin with time, even with much more than adequate heatsinking.

They are squirrely little critters, thats for sure.

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Indeed. I think nearly every luxeon I tested for Vf shift shifted down into the next lower Vf bin.

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evan9162 said:
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They cannot (I don't think) be using an actual integrating sphere for flux measurement on line.


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Actually, (surprisingly) they do. A 6" integrating sphere is used for measuring lumens. The test procedure is outlined in application brief AB08, on page 13.

Although my first idea was the same as yours - that they use a lux meter at some calibrated distance and use a simple conversion. But they go all out and use an integrating sphere.

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Wow! That's got to be some fast mechanism! (Or a bunch in parallel!!)
The variability between LS's of the same bin ia going to continue unless they further expand their binning.

The bottom line for me is they keep getting better,compared to a year ago! We're still playing the "lottery" and will continue to do so for the forseeable future. (Curse Future! /ubbthreads/images/graemlins/grin.gif )

Larry

PhotonFanatic is right.

I'hv been visited LumiLeds,Penang factory years ago and I saw each emitter is being checked for characteristics (Vf, Flux, Color) and automatically falls in many magazine (carrier - this is why we call "BIN" ) having bar code label. Then it transfers to automatic soldring line, where it solder into MCPCB and granted a barcode (BIN Code) or laser marked, thereafter.

By the nature, however, the measured characteristics in Flux and Color may have a variation. This is why same BIN has a slight difference in color. But this variation is being decreased now, as someone said.

At a new factory, LumiLeds will improve more, I hope.

Warren,

Too bad they don't bin them at a useful temperature (they use Tj of 25C (LED die temperature). You move off that temperature and the Luxeons are going to get squirrely, each one doing different things.

It adds to the whackyness of the "binned" parts, once you take them up to an actual operating temperature. You put 1000mA into a Lux III in accordance with the datasheet, that die is going to heat up 60C, you put it on a typical heatsink, and its going to rise even further, due to the heatsink temperature being hotter than ambient. Those Luxeons that have a die that is emitting are below the narrow optimum wavelength for phosphor light conversion are going to shift to a longer wavelength and the spectral output relationship between the blue LED and the phosphor will change, in this case increasing the green/yellow/red output, into the yellow-green area.

If a LED was at the optimum wavelength, it would shift to a longer wavelength, then the green/yellow/red output of the phosphor would drop, shifting the color more towards blue.