5. CHECK AND CORRECT
Examine the board for obvious errors. You can fix broken traces by filling in the gaps with a permanent
marker such as a fine-tipped Sharpie. Use a hobby knife to separate any traces that have smeared together.
Take the time to do a good, thorough job with this step, which can make or break your final product. For this
reason, it’s smart to print several designs, rather than pinning all of your odds on one.
6. ETCH THE
The chemicals used in etching are
corrosive, and their fumes are irritating.
Follow proper safety procedures, wear
a mask (or work in a well-ventilated
area), and protect your eyes.
There are different types of etching
chemicals: dry and liquid. Dry chemicals are less expensive, but require
dilution, as directed on the packaging. For this project, we recommend
ammonium persulfate, available at lab
and electronics supply stores. You will
need about 1 quart of etching solution
(etchant) to etch a 6" board.
Etching time is related to temperature. A small increase in temperature
drastically reduces the time needed to
etch a board, but too high a temperature makes the etchant too aggressive and gives off fumes. Aim for a
temperature of around 125 degrees
Design houses have temperature-controlled etching tanks. For etching
at home, you just need a stove, a large
pot, and a plastic tray for the etchant.
Fill the pot halfway with water and
heat to a simmer, but not a boil.
Put the PCB in the tray and place
the tray on the simmering pot. Then
slowly pour the etching solution into
The steam from the pot will slowly
heat the etchant and increase the rate
Etch the PCB on the stove.
Etching in progress.