The board was laid out to fit within a 50mm square so that it could be manufactured by one of the discount Chinese prototyping houses such as Seeed, ITead, PCBWay and Elecrow. For this size of board I choose Elecrow and for US$9.90 plus delivery I can get ten copies in about two or three weeks.
Time passes. Two or three weeks worth of time as it happens…
I made a small mistake on the Gerbers for the USB connector. On the footprint I include a guideline on one of the mech layers to aid positioning of the connector at the board edge and I mistakenly included that mech layer on the Gerber export with the result being a small sliver of exposed copper at the board edge on both sides under the USB connector. It makes no difference to the viability of the board but I find it annoying because I know it shouldn’t be there!
I’ve included M3 sized screw holes that can be used for adding ‘feet’ to the board so it’s lifted above my work surface and if you look at the back you can see that there are some handy quick-reference tables that identify which pins are connected to the commonly used peripherals.
Now it’s time to build it. I don’t have a paste stencil for this board so I opted to build it in several stages. Firstly I tinned all the surface mount pads with solder. Secondly, I reflowed the larger surface mount components such as all the ICs, the inductor and the USB connector using my bluetooth reflow oven. Thirdly I attached all the smaller 0603 and 0805 components using hot air and tweezers and finally the through-hole components were soldered into place using an iron. A quick wash with hot water and fairy liquid followed by drying overnight and she’s ready to test.
Looking pretty sweet I think. But does it work? Let’s run through some tests to see what it can do.