I created a surface mount design 4-layer board. Below is the computer 3d visualization of what it will hopefully look like when it comes back from OSH Park in a few weeks.
Below is what the computer had auto-generated for me, I tried to use a similar space profile since you pay by the square inch, but reordered some of the parts so the traces worked out...
One thing I need to watch out for is that U3 is upside down, so pin 1 goes in the bottom right. I did this because it saved a bunch on the traces, but perhaps consistency would have been a better plan.
I've never done a 4-layer board before, so hopefully I used the proper values for the Via holes & I end up with decent connectivity. I put the data signals on the front and back of the board, and put VCC and GROUND in the middle layers of the board. I read somewhere that you typically put data in the middle layers and GROUND on the outside layers, but if you are hacking a board it makes more sense to put your data layers on the outside, so that you have the opportunity to fix something if needed.
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