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Please see this datasheet here for QBLP615 LED.

The LED part top and side views are contained on page 3.

enter image description here

The recommended PCB footprint is shown on page 9.

enter image description here

Why is there a middle pad in the footprint and what is its purpose?

How should the third pad be put into the schematic part creation in Altium designer since it has no matching pin in the actual device?

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    \$\begingroup\$ Looks like a thermal pad to me. \$\endgroup\$
    – Ryan
    Commented Apr 19, 2022 at 23:42
  • \$\begingroup\$ I see, so assuming this is a thermal pad, what are the guidelines on how to actually connect it on the PCB? I think it needs to connect to a larger copper pour on PCB. \$\endgroup\$
    – gyuunyuu
    Commented Apr 19, 2022 at 23:51
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    \$\begingroup\$ @Quantum0xE7 I connect them to the ground plane, as that’s an easily accessible copper pour anywhere on the PCB. \$\endgroup\$
    – user110971
    Commented Apr 19, 2022 at 23:54

1 Answer 1

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it's a leveling pad to support the lens part of the LED to make sure the led lays on its side at 90 degrees instead of leaning downwards towards the PCB.

As there's a possibility of this pad touching the exposed substrate pad of the LED assembly and the datasheet doesn't say which terminal that will be, leave them unconnected

If you're ok with the leds sitting slightly crooked you can omit this pad.

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  • \$\begingroup\$ Does this mean that it will not need to be soldered? \$\endgroup\$
    – gyuunyuu
    Commented Apr 20, 2022 at 3:20
  • \$\begingroup\$ There's no connection needed, solder would form a pillow shape and tend to lift the lens. \$\endgroup\$ Commented Apr 20, 2022 at 3:24

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