Electronic – Cover element on LED component

automotiveledsemiconductors

From time to time I come across a solution in which uses an LED as in below picture:

enter image description here

This particular component is placed inside the module located in car interior. Button backlight application.

The base LED [PLCC-2 Package] is blue color LED. The top cover material changes the light to white, so I assume this cover material is actually a phosphorus layer. This is a common approach of achieving white color but usually the phosphorus layer is integrated inside the PLCC-2 package (The die is sunk in phosphorus line on below picture.)

enter image description here

What is the purpose of this additional cover?
My guesses are:

  • Specially mixed phosphorus layer is added to finished LED in order to achieve exact white color coordinates.
  • Manufacturing process improvement: one line for blue and white LEDs with additional process for white.

Is there any LED expert that could confirm this?

Best Answer

I received confirmation from LED supplier:

  • This solution results in better light homogeneity than die sinking method.
  • It is very rare because it's patent protected.
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