Since I was ordering 5 new PCBs to replace the ones I had already tried soldering, I decided to take the opportunity to update the PCB specs and then just replace all of them. Here is a side-by-side comparison of the order images from PCBWay. (once I have the new PCBs I will also post side-by-side photos).

The changes are:

• Traces are 0.4 mm wide instead of 0.2 mm (not accurately represented in the above low-res image)
• Mounting holes have been increased in diameter to 3 mm
• Solder pads for wires have been increased from 1.6 mm wide to 2 mm wide
• Wire holes have been increased from 0.6 mm to 1 mm
• Default REF** labels on mounting holes and solder pad have been removed/updated
• Solder pads for wires are now labeled according to what they connect to
• Board is slightly longer and slightly wider to accommodate larger mounting holes
• Arduino is positioned closer to the top of the board, also to accommodate larger mounting holes
• Wire holes are closer to the Arduino to make room for useful labels

The larger mounting holes mean that I won’t have to drill them out to fit the screws I have, as I did with the first batch.

The larger wire holes will accommodate up to 20 AWG wire (technically 19 AWG, but nobody makes that). I had ordered some 22 AWG wire before deciding to update the boards. I will probably order some 20 AWG wire and just use the 22 AWG for something else.

I was careful to keep the centers of the mounting holes (relative to each other) the same as before so that I can still use the standoffs as they are currently on the control panel. However, the old boards were pretty close to each other, so the extra width of the new boards might make that impossible. Worst case, I will have to buy more hardboard, remove all the components from the current control panel bottom layer (including the glued-down SD holders) and recreate that layer with the new hardboard. I really hope it doesn’t come to that!