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Flat Sections in LED Leads -- Why?
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rediv:
Possibly dumb question, not sure where/which forum to ask...

I needed some white LEDs and ordered these without looking at the mechanical diagram:

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwiV_pacwbn0AhWQRDABHRNbCA8QFnoECAcQAQ&url=https%3A%2F%2Fcree-led.com%2Fmedia%2Fdocuments%2FC512A-WNS-WNN-942.pdf&usg=AOvVaw3QdQwqfQ8r9sg_H6kaspxO

There are flat spots on the leads that prevent fully inserting the LEDs into my PCB.  Never seen that before.  What purpose do they serve?

Thanks.
flolic:
Exactly that.
Infrared_Fred:
I think the point of the flat parts is that if the LEDs get fully inserted to the epoxy case topuching the circuit board, overheating is more likely, especially during something like hand soldering, where the time of heat applied to the leads may be longer than the heat it gets during wave soldering.  Also, having air space with exposed leads would probably give a lower operating temperature for the LEDs, which gives a longer lifespan since heat kills LEDs. 
eti:
Crude but effective stand off
Gyro:
It also allows for some differential expansion between the epoxy package and the PCB.

I bought some LED car lamp replacements (as a light source for a microscope), where the LEDs were flush to the board. Even under-running them, they didn't last long - they started the flashing behaviour characteristic of detached bond wires (package stress).
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