when I was in junior high school, I made a circuit board, drew the circuit diagram with paint, and then put it in liquid medicine (ferric chloride) to replace the corroded copper skin without the protection of the paint pen, and then drilled a hole to form the waxed paper corrosion method. 1. Making the copper-clad plate Cut the copper-clad plate according to the size of the printed layout to make it consistent with the size of the actual circuit diagram, and keep the copper-clad plate clean. 2. Printed circuit on copper clad laminate. Tile the wax paper on the steel plate, carve the printed layout on the wax paper with a pen according to the ratio of 1:1, cut the printed layout on the wax paper according to the size of the circuit board, and lay it flat on the copper clad laminate. Mix a small amount of pigment and talcum powder into a thin and thick material, dip the printed material with a brush, evenly coat it on wax paper, and repeat it several times to print the circuit on the printed board (copper plate). Note: it can be reused and is suitable for making a small number of PCB boards. 3. Corrosion of copper clad plate Put the plated copper plate into ferric chloride solution for corrosion. 4. Clean the printed circuit board. Wash corroded printed boards repeatedly with water. Wipe off the paint with banana oil and clean it several times to make the printed board clean without corrosive liquid. Apply a layer of rosin solution and dry it before drilling.