Steam your PC Boards
By Peter Reilley <email@example.com>
I have tried all sorts of ways of pc boards,
except for plotting with ink on copper directly. I don't
have a suitable plotter.
I have tried transparency film and release paper with only
The best luck that I am having now uses ordinary copier
paper. I print on the paper at normal density. I am using a
"super black" toner cartridge from Black Lightning. I don't
think that this is necessary because I tried the output from
another printer with an ordinary cartridge and got
equivalent results. All of the following technique is with
the super black toner.
I prepare the copper surface by sanding it with
number 320 wet sanding sand paper. I do the sanding dry
(don't know if this matters). I sand in small circles so the
scratches go in all directions so the adhesion will not have
a perfered axis.
I iron the paper onto the copper with the iron at 170
degrees C, that is the highest temperature on my iron. The
fuser in my laser printers (LaserJet II and III) runs at 160
I iron for about 30 seconds on my counter top with a paper
towel between the board and counter top. This provides
insulation and a slight springiness to the board as I iron.
I iron enough to insure that every part of the paper is
heavly pressed onto the board.
Immediately after ironing I place a wet (dripping)
paper towel on the ironed on paper and press the iron onto
the wet towel. This drives steam into the paper. Without
this step the paper will shrink and pull the toner off the
copper. The steam causes the paper to swell up and relieve
The iron should be placed on the towel for a split second or
the paper will dry out.
I then soak the paper with dripping water and let it
sit for about 5 minutes. The paper should be completely
soaked and swelling between traces.
I then rub the paper with my fingers under running water.
The paper will begin to ball up and come off in layers. I
rub it until I get as much off as I can.
At this point the traces should be well attached to the
copper and not at risk at coming off. You will find that all
the toner has a paper fibers imbeded into its surface.
This is not a problem in most cases.
The problen arises when the fibers bridge the gap between
traces or pads. To solve this I scrub the board with a brass
brush. This brush is like a tooth brush with bristles made
of fine brass wire. The brush will break the fibers that
bridge gaps between toner areas. Do this while the board is
Let the board dry and inspect all the toner for
fibers that would prevent proper etching. Pick any remaining
fibers away with an exacto knife.
While I etch the board, I periodically scrub the surface
with a real tooth brush to insure that the fibers are not
blocking etchant access to any portion of the exposed
copper. Do not use the brass brush in the etchant as it will
be desolved itself.
I have made a number of small boards up to 2 by 4.5
inches using this process and some with very fine traces and
I complete the etching of one side before I apply the toner
to the other side. I don't know it this process will scale
up to larger sizes well.
It seems to me that the steam step is particularly
important. Before I did this traces would pull off at the
edges of the board as the board cooled.
Originally posted on the
sci.electronics usenet group, November 3, 1992.