Galileo update & DIY solder mask
The Galileo project is progressing, and the next step is a board to drive its many many LEDs.
Dave B. put together a schematic and board in EAGLE for this purpose, based around the TI TLC5940, a 16-channel LED driver, and had the boards made at DorkbotPDX. Schematic is here, board layout here.
(Sorry for the light fogging. I really should just get a real macro lens instead of putting an old Series E 50mm on extension tubes.)
Paul and Jim then used the laser cutter to make a solder mask out of acetate film (i.e. garden-variety transparencies). The cream layer in EAGLE provided the mask to cut, and here’s the stencil created from that:
Here are two of the attempts to laser-cut this stencil from acetate sheets. The imperfection on the top one (see the right of the two holes on the bottom left) came from etching the edges of the hole rather than rastering it, supposedly; the bottom one came out a bit better.
Here’s one finished board, having had solder paste applied through the stencil and reflowed on a cheap electric skillet. It looks good aside from a solder bridge at the chip’s 2nd- and 3rd-to-last pins:
Keep following the Wiki page - the project progresses pretty regularly and Jim updates the page.