CNC mill phase 4: PCB fabrication

By now I’ve got a pretty good system down for fabricating PC boards:

1. print artwork onto transparencies
2. laminate the dry film resist onto copper
3. expose the board on the UV light box
4. develop the film, rinse
5. etch the PCB in a tupperware in a sink full of warm water (I’ve been experimenting with acid cupric chloride, but my go-to is still ferric chloride), rinse
6. strip the film off with acetone & tin plate the board with Tinnit (also in container in warm water), rinse with ammonia solution
7. drill & trim board
8. dab on solder paste and place components
9. reflow solder in the toaster oven
10. hand-solder through hole components

This is basically the process I followed this time, but this was the biggest PC board I’ve made to date at around 11″ long. To start with, I couldn’t fit the whole thing on a 8-1/2 x 11″ transparency out of my laser printer, so I had to print it in two pieces and tape them together.

PCB artwork transparencies

I also couldn’t fit the board in my typical etching tray, so I had to use our good Pyrex baking tray for the etching and plating. Otherwise the process went smoothly. I intentionally sized the board to just fit into my reflow toaster oven, and despite using expired solder paste the boards came out pretty good.

PCB - ready to etch

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