When did Lux3 lead structure change?

I just noticed a difference in the leads of the Luxeons. I can't seem to find this in a search. If this has been discussed before - point me the way...

Notice the way the leads exit the packages in the photo below:

Right-Lux3 star, Center- Lux3 emitter, Left- Lux LD stars
See the difference between the right and center Lux3's?
Is there a date when Lumileds switched over the leads?
I assume the fatter leads allow better heat dissipation.

The Lumileds data sheets show the difference too - between the emitter and star that is.
The star is shown with fat (right) leads, and the emitter is shown with narrow (left) leads.

Curious, Crux

never seen stars with thin legs before.

1W stars had thin legs

Stars using the new star construction (emitter directly bonded to the aluminum heat sink with a raised PCB surrounding the emitter) use the fat leads. This includes Luxeon-III, as well as 5W Luxeons. 1W stars use the thin leads, and are mounted on top of a thin PCB layer, which is on top of the aluminum heat sink.

The leads do not really dissipate any heat - the only connection between the leads and the LED die is a thin gold bond wire, which won't transfer much heat at all.

Evan

Both the Lux3's in my photo (left and center) show different leads. It seems Lumileds makes the lead structure different depending on where they will be used; stars use fat leads, bare emitters use thin.

It now makes sense that the lead form needs to be different in order to accomodate the PCB thickness of the star versus the single mounting plane of the emitter.

No big deal on this, it just caught me by surprise when I first noticed it.

I'll go back in the basement now...

Crux

Yeah, it's too bad they don't leave the L3 and L5 emitters using the fat leads - then (at least for the L3), you could differentiate them from 1W emitters (the 5W is pretty obvious on it's own).

[ QUOTE ]
Crux said:

Both the Lux3's in my photo (left and center) show different leads. It seems Lumileds makes the lead structure different depending on where they will be used; stars use fat leads, bare emitters use thin.

Crux

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Yep, that's how it is done.

The consensus here was that Lumileds is using the fatter leads on the stars for whatever reason, but the solder pads on the star that the end user uses for hook-up are remained the same as the 1w stars, but the emitters wouldn't be if they used the fat leads. This would cause problems for companies using 1w emitters since they couldn't upgrade to the Lux III without changing the layout of the solder points for the emitter on the PCB, so Lumileds kept with the thinner leads for ease of product upgrade by the end user.

So what I'm trying to say here is that Lumileds did this so that the leads would be the same as the 1w parts so end users (big companies) wouldn't have to change their PCB's to upgrade to the Lux III.

Anyway, to answer your question, "When did Lux3 lead structure change?" - It has always been like this since the Lux III came out.