PCB etching

A set of tools and chemicals for creating electronic circuit boards.

Contents

• boards covered with copper and a photosensitive material (exposed area gets etched away)
• the Resin printer
• a jar with 2% NaOH solution
• a jar with used NaOH solution
• a plastic bottle with NaS₂O₈ powder
• a jar with NaS₂O₈ solution
• a jar with used NaS₂O₈ solution
• a chipped glass bowl

Danger

All those chemicals are somwhat corrosive or poisonous. DO NOT flush them down the drain before deactivating.

Experimental

This setup mostly works, but the disposal of spent chemicals has never been tried yet.

Process

TODO: expand

1. When designing the board, use 0.1mm resolution at minimum. The etchant will remove copper, so traces will be narrower and spaces larger than designed. 0.3mm trace width recommended for no breaks due to dust.
2. Use UVTools to convert a Gerber Cu file to 3d printer format
   1. Open any print file for this printer
   2. Use the "PCB Etching" tool: Mirror, invert, 4 min exposure.
   3. Use the specially prepared printer USB stick.
3. Cut board to size with a metal saw
4. Remove build plate from printer (IMPORTANT)
5. Dry run the exposure print (without board)
6. While it's running, manually place the board on exposed area and close the printer
7. Dunk board in NaOH solution, see red stuff flow. Continue until shiny copper visible.
8. Wipe, drop board in NaS₂O₈ solution
9. Fill the glass bowl with some hot water, put NaS₂O₈ jar in the bowl, wait 10min. Copper should be gone, greenish board clearly visible.
10. Use pincers to remove the board from the solution

Cleanup

Used NaOH developer can be diluted and flushed in the sink.

Used NaS₂O₈ solution MUST NOT be flushed in the sink, as it now contains copper. TODO: how to deactivate copper?

Post-processing

After the board is soldered, the copper remains exposed. Use the protective lacquer from the PCB supplies to cover the copper. (TODO: how to use it?)