How to Etch With Hydrochloric Acid & Hydrogen Peroxide

By Barbara Stanley

A simple etchant can be made from common chemicals found at local hardware stores. Hydrochloric acid, also known as muriatic acid, is generally used to clean concrete foundations or patios. A pattern is either transferred or printed onto a 3 1/2-by-5 inch circuit board. The circuit board is made of copper that covers an insulator. Any indelible marker will work to trace a pattern onto the board, but some people prefer using a thin permanent marker to control the thickness of the lines drawn. The pattern could be transferred by ironing a copy of the pattern printed on photo paper. You would need to make a separate copy of the front and back of the pattern and iron the front to one side and the back on the flip side.

Things You'll Need

  • Circuit board
  • Indelible marker
  • Goggles
  • Vinyl gloves
  • Glass or plastic bowl
  • Hydrochloric acid: 38 percent by volume
  • Hydrogen peroxide: 3 percent by volume
  • Nonmetallic tongs
  • Acetone or mineral spirits

Step 1

Draw or iron a transfer of your pattern onto the circuit board. If you draw directly onto the circuit board, wipe off mistakes with a 1-to-1 mix of acetone and alcohol, then start over.

Step 2

Put on the goggles and vinyl gloves before mixing the chemicals. In a large nonmetallic bowl or container, mix 1 part hydrochloric acid with 2 parts hydrogen peroxide. For example, you would use 1 cup of the acid to mix with 2 cups of the peroxide.

Step 3

Slowly add the acid to the hydrogen peroxide. Never add the hydrogen peroxide to the hydrochloric acid, as it could cause a reaction that might splash the chemicals into your face.

Step 4

Mix enough chemical solution to totally submerge the circuit board. Agitate the board in the solution for 10 to 15 minutes, using a pair of nonmetallic tongs.

Step 5

Mix the acetone and rubbing alcohol together. Dip a paper towel into the solution and wipe both surfaces of the circuit board to stop the etching process and remove any remaining lines from the marker.

Step 6

Dispose of the etchant properly or store the solution in a glass or plastic container with a lid. Mark the contents of the container and store it in a responsible place out of heat and excess light and out of reach of children.

Tips & Warnings

  • Do not use metal of any kind while etching circuit boards. The metal will cause a chemical reaction that could burn whatever it comes into contact with.
  • The solution will turn a green color during the etching process. This is normal.