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While initially designing this layout, I added a large capacitor to ease current demand on the power supply. This capacitor may not actually be needed if you are not doing a lot of animations on your LED strip.

What is the capacitor for?

The capacitor between +5v and GND performs two functions in this circuit.

1. Filters noise from the power lines.
2. Acts like a power reserve to prevent the power supply shutting down when the LEDs go from off to full brightness.

As I understand it, if you go from LEDs off to LEDs full brightness, the power supply sees this as a short circuit. So if you have a switching power supply it may just shut down. When using a capacitor, the current is drained from the capacitor first, slowly ramping up the drain from the power supply, so the change seems less drastic.

In my software, I plan to fade the LEDs in when turned on, so the demand should in theory be easier on the power supply.

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Take the above with a pinch of salt, as I'm piecing together bits of infomation from different sources. If what I've said is patently wrong, then please feel free to reply below to help me understand!

The current PCB board uses a 7.5mm pitch capacitor, with 16mm diameter. As this project is low voltage, theres no real need for such a large pitch.

The capacitor could be swapped for a 5mm pitch 12mm diameter footprint. This would allow the board to be shrunk a little, and reduce filled board height 20mm.

Furthermore, you may not need a capacitor at all. See the discussion here.

Currently the DC jack footprint is comprised of 3 drilled holes. This makes soldering a little tricky as the holes requie a lot of solder to fill.

Apparently the better method would be to actually route the holes to accommodate the rectangular pins of the Cliff DC-10A jack.

For more information read about slotted holes on the Autodesk Blog.

In the first design of the board, I routed the data line below the capacitor. This has the disadvantage that it splits my top layer ground pour in half.

If I routed the data line above the capacitor then the ground plane would not be split as drastically.

This is not a huge issue, as the bottom layer has a nice large ground plane, but is still probably worth doing!