This is a copy of a reply I just posted in sci.electronics.design. I thought I would
post it here as well for you folks to pursue if you are interested in it. Maybe
Crankorgan John could go work up some plans for it. It's promising technology
but I like working with boards more than belts and gears.
> >Has anyone every tried putting Etch resist Ink in a BubbleJet or InkJet
> >printer and printing a PCB design directy onto the copper side of a PCB.
As a matter of fact I have. I thought about turning this into a commercial product, but
I just don't have the time. Too many other projects to do. I even went so far as to
turn an inkjet into a flatbed plotter. The problem there is converting the stepper motor driven
motion of the platten roller into linear motion with the stepper using belts or gears or
electronic gear ratio reduction for the steps. All three methods work but I like the
belt and gears method best.
I tried modifying printers to feed a board through as is, but that was just too much trouble.
Some would feed thin stock just fine but others wouldn't. The flat bed approach solves that.
Plus the flat bed approach with some simple guide pins lets you do double sided boards with
accurate side to side registration.
For ink, I found two things that work well standing up to the etchant.
Acrylic Floor Polish.
Shellac
Floor polish ( sometimes called wax ) ( I used the Future brand ) works well and won't gum
up the printheads as easily as Shellac does.
Floor polish is removed with Ammonia.
Shellac with Denatured Alcohol.
I used three different types of printers. A Lexmark where the head is built into the cartridge,
an HP where the printhead is separate from the cartridge but still uses thermal "bubble" jet
technology and an Epson which uses piezoelectric technology.
The winner was the Lexmark. Easy cartridge to refill and cheap enough to replace.
The problem in all this is that to use straight "ink" that is very water ( and then etchant ) proof
is, it will dry on your printhead orifices. The solution to that is a valve. One path to ink, one path
to a flushing fluid. Before you print the board, run a cycle of "ink" to clear out all your flush fluid.
Once you have finished printing, run a cycle of flushing fluid to purge all your "ink".
Ammonia diluted with water works great on the acrylic polish ink. You can even put a little regular
inkjet ink into it to color it so it's easier to see on the PC board blank.
Once you get the "ink" on the board and have etched it, you can clean it off with just a quick spray of
Windex or other ammonia based cleaner.
I have no idea as to the benefits or problems with acrylics as conformal coatings but I plan to try it
some day on a finished board. Just dip it in Future polish and see what happens!
Another thought I had was a PVA ( poly vinyl alcohol ) based ink but the PVA I had on hand didn't
thin out well to run in an inkjet. The acrylic ink worked well enough so I didn't really pursue PVA much.
Now go have fun......
later,
Larry Edington.
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