Week Two: PCB Fabrication and Surface-Mount Soldering

I used Valentin Heun’s layout with the snap-off programming circuitry, because it seemed like a neater solution than de-soldering jumpers. I cut the PCB on the Modela using default settings in the Fab module, except that I modified the cut depth to 2 mm since others were having trouble with shorts.

Initially, it looked like these settings had worked. But later as I was adding components and checking connectivity along the way, I realized there were actually three shorts on the board:

I took the lazy approach of cutting the shorts with an exacto knife. This was definitely a bad way to do it (nearly broke some neighboring traces) but it worked this time. The components I used were as specified in Valentin’s diagram, except for the two 18 pF caps, which we didn't have, so I replaced them with 10 pFs.

My ISP was programmed correctly using one of Amir's ISPs, but it doesn't work, that is, it doesn't show up in the list of USB devices on any of two Macs and one Linux machine, even though the chip does get 5V from the port. (At least, when I wedge it in there with a piece of paper underneath--the board alone is too thin to fit in securely).