evan9162 said:I have a lot of older luxeons that are doing this too.
The silver turned gold part you are seeing is the top of the heat sink slug of the emitter. The hexagonal shaped silicon submount is thermally attached to the top of the slug, and the square shaped die (covered by yellow phosphor in the case of white Luxeons) is attached to the top of the silicon submount.
The heat sink slug is copper plated with silver. The silver is likely tarnishing. I have several luxeons with many thousands of hours on them that are exhibiting the same phenomenon. The silver is tarnishing on the top of the slug. It's not a result of poor thermal management (the luxeon is not getting overly hot) since many of mine which have tarnished have excellent heat sinking and only get a few degrees above room temperature.
I don't think there's anything to worry about. The silver on the top of the slug tarnishing won't affect the device in any way.
jtice said:exactly what monkeyboy said,
if the reflector is filling up completely with the reflection of the LEDs yellow phosphor, then its designed well.
Some reflectors dont use their entire surface area to actually reflect the LED.
win67 said:What's that? The Luxeon I inside my Fenix L1P gets visible golden, round the die/phospor of the emitter, where it is normally silver plated...
Never seen this before....
evan9162 said:He's not talking about the phosphor reflecting in the reflector, he's talking about the tiny silver ring around the phosphor that's part of the emitter its self - the top of the heat sink slug.