White LEDs are a combination of a blue LED and phosphor. Due to the nature of the beast, they have a limited life because of the materials used.
That's bullshit. The phosphor can easily be applied to the lense and essentially make the LED part exactly the same as a blue LED.
Yeah, phosphor is applied to the cup or the surrounding area of the LED. Blue is emitted, absorbed, and the excited phosphor emits as white. YAG is the most common for the high-power lighting LEDs, it's what gives COB LEDs their distinctive piss-yellow color. Look at a white LED with a spectral analysis. You'll mostl likely see one in deeper blue and one in yellow-green. You see it as white.
Lower power whites used to just coat the cup with phosphor, that's why the old ones had a blue halo around the white light. I need to pick up some new 5mm units and see if they still do that.
The phosphor eventually changes over time and emits less light. I'd assume it has something to do with heat cycles and moisture and simple aging, but I have no idea. Never really studied the effect because I'm not going to be working in the field.
The point is there is nothing there to make them fail. It is planned obsolescence.
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