Hi:
I have just downloaded Kicad 7. My new board needs to have Thermal relief for High Power white LEDs soldered on the front layer with copper thermal dissipation via the Rear filled layer. I have been Unable to figure this out, do I use vias or another transfer mechanisms to accomplish this? The back layer is a no-net. Driving me crazy!
Thanks,
Tom
Greetings,
Is your question about getting the tool to generate some particular geometry you have in mind, or more along lines of PCB design practices?
In the latter case yes, it’s typical to use plated vias as a through-board thermal transfer path. There are app notes such as this one floating around that can offer more in-depth discussion on the topic.
Hi:
I haven`t used Kicad in a while so first just knowing the steps to create a thermal pad similar to those described in the CREE document would be most helpful. I have tried many ideas without success.
Thanks,
Tom
HI:
I should also mention I have used Kicad 5 to create several 4-layer very densely populated boards, but never needed to consider the Thermal Pad with PTH vias for heat transfer. Im stuck on the mechanics of doing that. My project will be using some CREE LEDs- XBDAWT-00-0000-000000G53
Thanks,
Tom
After reading more of the CREE doc I realized all I had to do was re-establish a pin# 3 for each LED for the thermal pad (“free” pin). On the schematic all of the Pin 3 terminals were wired together. For my schematic Kicad called these connections NET-(LED1-X). In the Copper Fill properties I selected the same NET-(LED1-X). Now I can use vias for thermal transfer to the back filled copper layer. My final step will be looking at CREE`s recommendations for the vias and matching those specs as best I can to what my board maker can do.
Thanks-
Tom
Now that I have the thermal relief solved, my last goal is to place a “Mask” on the center heat transfer pad for each led (see pic below). Again, I am stuck. I am editing the footprint and on it placing what I think is a F.Mask rectangle to accomplish my goal. but it is not showing up as expected when viewing the footprint in the pcb editor and when using the 3d viewer. The mask should be between the two vias in the heat transfer pad. Again, any help is appreciated.
Tom
This is the footprint being edited… the mask should sit in the middle of Pad 3.
