Circuit Design
First, the etcher designs a circuit board image. This is done for free by a hobbyist using a program like Eagle at Cadsoft Online (see Resources below) or a program like Microsoft Paint.
Print
Next, the printing begins. The circuit board prints as a mirror image of the board desired. The printer is usually a bubble jet or inkjet printer, though laser printers are also used. The image settings are set as high as possible for the darkness and resolution of the ink layer for your printer. The image is scaled up or down to the proper image size. The paper used is commonly the "photo basic gloss" found at office supply stores since the ink transfers well when heated.
Wafer Cutting
The circuit board etcher puts on safety goggles. She cuts the wafer board to match the circuit board. She wears gloves so that the oils on the fingers do not interfere with the etching. Using a standard wafer board means that the etcher should not use a pair of scissors or tin snips since the board is brittle and will crack.
Prepare Copper
The etcher prepares the board by scrubbing it lightly with sand paper (available in the cleaning isle of the grocery store) to remove oxidized copper and surface dirt or oil. Acetone cleans the surface of dirt and oil (if you did happen to touch the board). The board dries off completely. Doing this process outside and wearing a mask ensures that no toxic metal or hydrochloric acid is inhaled.
Melt Ink
Masking tape is used to attach the printout, with the ink side down, onto the copper side of the wafer. An iron on the highest setting (being careful not to burn the paper, of course) irons on the ink from the paper on the surface of the copper. The ink will melt and stick to both the paper and the copper surfaces.
Remove Paper
The etcher soaks the paper in water. Peeling off the back of the paper allows water to penetrate the high gloss finish and to swell the paper so it rubs off using thumbs. This leaves the ink on the etched circuit board.
Etching
The etcher, still wearing the goggles, is also careful not to get acid on anything (including himself). The etcher is careful not to inhale the acid fumes, which will burn the lungs in a way that won't even be felt for a couple of days.
Drilling
Pouring a solution made half from 30 percent muriatic acid (the term for hydrochloric acid at the hardware store) and half hydrogen peroxide (3 percent, from the pharmacy), the etcher manipulates the boards with plastic forks. The etcher may even pull it out to rise and check the progress of the dissolving of the copper. If the solution has not been used recently, the copper may be checked by looking through the solution since the solution will be clear enough to see the progress.
Final Touches
The etcher cleans off the ink with more acetone and scrubbing. Putting a drill bit in a small drill press, the etcher drills a hole that barely fits the wire leads of components he inserts. Most of the time, a 0.04 millimeter drill hole is more than enough for the piece to fit in, but he also drills larger holes for 0.80 millimeter screws (or larger) that will attach the circuit board to a mounting inside of a case.
Trade Secrets
When soldering an electronic component to the copper, the solderer holds the piece at a point on the lead above the hole with a pair of metal tweezers which helps to dissipate heat and protect the component.
