Making a printed circuit board (PCB) involves placing a design on a thin board covered with a thin coating of copper. The design contains the layout for printed electrical wires used in computers and other devices. The exposed copper left on the board must be removed by use of an etching material, or etchant, such as ferric chloride, a yellow orange dark salt. Some tips on its use make the process quicker and more effective.
Powder vs. Liquid
Ferric chloride, or FeCl3, a mixture of one part iron and three parts chloride, can be obtained in either liquid or powder form. For the purpose of etching a PCB it must be in liquid form, so the powder has to be mixed to create a liquid. The powder costs less, but some dangers can arise during the mixing process, so it should be avoided unless great care is taken. According to the Material Safety Data Sheet, ferric chloride has several dangerous aspects. It is a corrosive that can cause burns to any part of the body--for example, through inhalation.
Heat
Heating ferric chloride makes it easier to use and the etching job goes much faster with warm liquid. Ferric chloride, when heated to decomposition, gives off toxic fumes. Therefore, only warm the liquid and be careful to avoid high heat. If any fumes start to arise, turn off the heat and ventilate the area completely with fresh air.
Square Sponge
One way to apply the ferric chloride involves placing the slightly warmed liquid in a container that has a lid. Then place the board in the container, put on the lid and shake the container slightly so the etchant gets all over the board and does its work. This can consume some time, waiting for the etchant to remove all the exposed copper. According to Tehnik Service, the use of a square sponge for etching finishes the process in one minute. This quick result arises from the direct application of the ferric chloride to the board as opposed to the board sloshing around in the container. It is the same result as scrubbing a pot as opposed to soaking it. Make sure the hands are protected from the corrosive effects of the etchant.
