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Galileo update & DIY solder mask

September 27th, 2011

The Galileo project is progressing, and the next step is a board to drive its many many LEDs.

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Center column of Galileo display

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.

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Unsoldered PCB

(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.

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Less-successful stencil

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More successful cut

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:

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Soldered PCB

Keep following the Wiki page - the project progresses pretty regularly and Jim updates the page.

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  1. Tyler Bules
    October 5th, 2011 at 23:24 | #1

    Its a little late now, but you guys could have possibly reduced the wiring for the rgb leds through charlieplexing. Leaves you with just 4 wires for every 4 RGB leds. 48 wires instead of 144. of Either way it looks really impressive.

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