Ferric chloride etches printed circuit boards in the semiconductor and computer industry. It is not the most aggressive etch available but is safer to handle than the common acid etches. You can make ferric chloride solution rapidly as needed and in the desired quantity from small to large batches. Disposal of ferric chloride requires special arrangements because it is a hazardous material. Ferric chloride is corrosive and prolonged exposure leads to dermatitis.
Instructions
1 Put on your safety goggles and latex gloves to protect you from exposure to the corrosive action of the ferric chloride. Wear these safety items whenever you are dealing with the etching solution.
2 Weigh out enough ferric chloride to make the concentration of the solution 200 gm per liter. To find out how much ferric chloride to weigh out multiply 200 times the number of liters with which you will fill the Rubbermaid tub.
3 Place hot water in a Rubbermaid tub up to the level you require for your etching project. Add the number of liters you used in the calculation of how much ferric chloride to weigh out.
4 Add the ferric chloride to the water slowly to avoid splashing any of the solution on you or into the work area. Make the addition while the water is still hot.
5 Stir the solution until the ferric chloride has dissolved. The etch bath is now ready for your parts.
6 Dispose of the solution after your etching is complete by adding sodium carbonate to the solution until the pH is between 7 or 8. You can test the pH of the solution by using a piece of pH indicator paper. When the solution reaches this pH range, the copper in solution will fall to the bottom of the tub as sludge.
7 Pour off the liquid after the sludge settles and dilute it further before pouring it down the drain.
8 Scoop out the sludge and collect it in disposable plastic bags for transport to your local waste disposal site.
