Connecting pad to thermal pour

[keethrax]

I'm trying to put together a board using a Cree XP-G LED. It has a thermal pad (3 in image below) that I can't seem to figure out how to connect to anything in KiCad.

If I add an LED to the schematic it only has the two connections (fair enough). I can then assign this as the footprint even though it has a third pad. But when I go to layout, I can't figure out how to make a pour that will connect to pad 3. When I use "Add filled zones" to create the pour, I get a message about "No net will result in an unconnected copper island" which is exactly what happens.

Since the LED schematic symbol only has two connections, I don't know how to connect pad 3 to a net back in the schematic step which would presumably allow me to connect it to a pour in the layout step. Alternatively, I don't know how to force the pour to connect without pad 3 being on a net. What am I missing?


 

[tox3]

You can change pin number of thermal pad to 1 or 2 on footprint to connect to one of the existing nets or you can create additional pin in schematic symbol of led with pin number 3.
Hope this helps.

[nali]

When editing your PCB layout you should be able to select the pad & hit "E" to edit the properties. You can then select the net (GND), plus also the connection type under the  "Local clearance and Settings" tab. E.g. you might want to force a solid connection rather than thermal spokes to get the heat out depending on the layout requirements of that particular part.

[poeschlr]

I highly advice against the hack suggested by @nali. Do not manually change the net-assignments within the pcb as you will lose this information on your next "update from schematic"! It is very bad practice to have the schematic differ from the layout in part because of this (but also because the schematic is the documentation and your documentation should agree with your product.)


Also KiCad version 5.1.4 (and newer, possibly also older) comes with a symbol LED_PAD which would be the perfect fit for your component.

[nali]

Yep that's better advice... ignore mine 

[keethrax]

Also KiCad version 5.1.4 (and newer, possibly also older) comes with a symbol LED_PAD which would be the perfect fit for your component.

I looked for a similar symbol but didn't know what it was called. Thanks! That solves my issue.