I need to design a custom power LED module with 3x4 power led layout.
Each LED consumes 9500 mW. So the cooling is crucial, and I need direct copper connection.
I have used a complete module in the past, but I need custom size this time.
The PCB is quite special, the led’s third (cooling) tab is directly soldered to the 1.8mm thick copper sheet, without any insulation in between.
Here is a useful article about it:
h.t.t.p.s.:././.jlcpcb.com/blog/JLCPCB-Direct-Heatsink-Copper-Cored-PCBs-Available-Now!
Here is the led datasheet:
And here is a ready-made module:
h.t.t.p.s.:././.www.uvledchip.com/uv-led-modules.html
(I need to modify mine to be 3x4, and a different size. So I need a pcb design.)
I uploaded the kicad project to github, link:
My questions are:
How can I “connect” the middle pad (heatsink pad) to “B.Cu” without any vias? So kind of show to manufacturing those pads are for direct copper connections, and also satisfy the design rules checker too? Is there any resources for direct copper core pcb design (in Kicad) ?
In schematic, where to connect the third led legs? (the cooling tabs). Right now, I just added a connector, and connected them together.
(sorry as a new user, I can only upload one image. There is a “screenshots” directory inside the github project. There is the schematic inside that folder too.)
Apart from selecting Direct Heatsink Copper for Base Material, a drawing should be attached to indicate which copper areas to make as direct heatsink / connected to the base. It’s recommended to select the Confirm Production File option so that before production you can make sure your intention has been correctly understood.
This is your answer. You will need to draw the direct-copper connection areas on a User layer, and then tell the PCB manufacturer to use that layer to fabricate the board. Talk to them first and see what they recommend.
This is where fabrication notes are critical! as the process a company does is unique to each one.
TWO options exist
A unique non-electrically connected pad of at least 1mm x 1mm square
ALL appropriate pads are all electrically tied together
Looking at the LED in question the middle pad is purely for thermal and thus a 3x6.4mm pad would suffice and left unconnected.
THe notes would then be “all 3.6.4mm pads to be direct heatsink for a total of ???”
have a 3rd unconnected pad and explicitly mark it as NoConnection
