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This is a rough, jot-note version. Feel free to flesh it out, add screenshots, or plain fix it.

To cut a solder stencil into a laser transparency:

  1. Add a section to your CAM job in Eagle. Output type should be HPGL and the only layer selected should be tCream. I'd suggest a filename of %N.plt
  2. Run the CAM job.
  3. Take the Project.plt file to the laser computer.
  4. In SmartCarve, create a “New” document.
  5. File→Import, Select your .plt file.
  6. Choose 1016dpi
  7. Modify→Scatter Group
  8. Modify→fill, Direction: X Single, 508, 0, CHECK “Delete Contours”, OK
  9. Set velocity to 40 and power to 1%
  10. “Carve Out”

Clean up the rough edges with wet fine emery paper. I used 1000 grit.

To use, I build up a “frame” of unpopulated boards around the board I'm soldering. Tape them down. Position the stencil and tape it down. I deposit a small amount of paste on the top of the stencil, then use a metal scraper to squeegee it across the board. It might take a bit of touchup if the paste missed any holes. Carefully peel up the stencil and remove the board. I find I need to clean the bottom of the stencil with isopropanol after every three boards.

Carefully place all SMT components on the board. Then “bake” the board in the reflow oven. Our oven is pre-set for a Tin-Lead profile. Plug it in. Place your board as near the centre of the oven as possible, then press the right button. At the peak temperature, once the heat turns off, open the door to allow faster cooldown. Watch the temperature! It's too hot to handle for longer than you might think.

smtstencil.1399693619.txt.gz · Last modified: 2014/05/10 03:46 by srw7
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