Curved Circuit Art: Make A Double Helix LED Lantern

Step 4 Etching the Curved Circuit Board

Cutting the Pattern
Pic5b shows how the vinyl shelf liner is cut with a double bladed knife and a thin long section is removed. This is done wherever you want the copper to be etched away.

Pic5c shows the double bladed knife which is easily made by bolting on two exact o knives on either side of 1/16" FR-4 circuit board material that has the copper etched off.

Etching the Board
Before etching the board in Ferric Chloride solution, the cut edges of vinyl should be burnished so the etchant cannot ooze under. I burnish by rubbing the rounded end of a Popsicle stick along the edges to make sure they adhere well. The whole thing can then be immersed in Ferric Chloride for about an hour at room temperature. Rinse the etched board very well with water before you peel off the vinyl shelf liner.

Cleaning the Board
Even with burnishing, some etchant will get under and stain the edges of the copper traces. I use the fine steel wool to polish away any stains or finger prints on the copper.