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 Post subject: Creating a new LED pattern and component
PostPosted: 15 Jul 2016, 10:48 
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Joined: 14 Jul 2016, 09:09
Posts: 1
Hello DipTrace Community,

I am pretty new to PCB Designing and Engineering. But I am trying to build a particular LED circuit and I am trying to use a specific LED for the design. Is there an easy way to import or create a pattern for the Luxeon Rebel LED? It is a LED with great performance but it is a complicated design with many thermal vias and an intricate shape for the pads. Are these thermal vias only necessary for boards without heatsinks? I am attaching a link to see the LED below. I also have a .dxf file from Luxeon on the LED, but the best I can tell it imports it like a Gerber would and doesn't act like a pattern when I do it. Any help is much appreciated, thanks in advance!

Image

http://www.lumileds.com/uploads/252/AB32-pdf


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 Post subject: Re: Creating a new LED pattern and component
PostPosted: 21 Jul 2016, 11:55 
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Joined: 20 Jun 2015, 14:39
Posts: 934
jerenkholman wrote:
"...Are these thermal vias only necessary for boards without heatsinks?..."
Section 3.2 of the Luxeon datasheet states "...Thermal vias are the primary method of heat transportation to the heat sink at the PCB bottom..."

In other words, a thermally-connected heatsink is needed on the opposite side of the PCB to keep what I presume is a 3W LED from destroying itself. Don't rely on the PCB alone to dissipate that much power/heat from such a small area. A cursory scan of the datasheet leads me to believe that the LED's thermal landing pad is electrically isolated, which should make designing that area of the PCB a bit easier unless you start playing around with high voltage series LED strings.

For your entertainment I have included a User Pattern library file named LED.lib (inside the LED.zip folder) containing the pattern shown below. I pieced together the Pattern from some of the drawing figures inside the manufacturer's *.DXF file and it should probably only be used as a starting point to create your own pattern. Take note of the manufacturer's drawings for examples of how to route the supply traces to the input pads. The circuitous routing of the supply traces either has something to do with electrical clearance issues underneath the LED or they are trying to add a little more thermal isolation from the rest of the circuit (just a guess). Please note that I cannot guarantee a proper fit or fire resistance for the included Pattern. The illustration below shows what the Pattern looks like and how it appears in the PCB Layout editor and 3D Preview. What follows is how to interpret the illustration...

Pattern
Dark Green Area: Top Mask (Solder Mask Opening)
All Through-Hole Pads: Top and Bottom Mask and Paste are disabled

PCB
Blue Area: Top Copper
Red Circles: DRC violations (ignore or change the DRC rules)

3D
Light Green Area: Solder Mask over Top Copper
Dark Green Area: no Solder Mask
Gray: Top Copper (without Solder Mask)

p.s. Don't forget to connect all thermal Vias and the Top/Bottom Copper Pours to the same Net. Specify Direct instead of Thermal Spoke connections for the thermal Vias. You will have to determine how the heatsink will be fixed to the opposite side of the PCB.


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Tom


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