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Subject: Re: Printing dircetly onro PCB copper side Part II
X-Newsreader: Microsoft Outlook Express 6.00.2800.1106
Date: Sat, 14 Sep 2002 06:05:40 GMT
NNTP-Posting-Date: Sat, 14 Sep 2002 01:05:40 CDT
Organization: Road Runner - Texas
As a matter of fact I have. I thought about turning this into a commercial
product, butI 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
For ink, I found two things that work well standing up to the etchant.
Acrylic Floor Polish.
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
The winner was the Lexmark. Easy cartridge to refill and cheap enough to
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 the acrylic 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......
"Coolkits" wrote in message
> Ok thanks for all your responses.
> It seems that with piezo inktjets it schould be possible to get some kind
> Etch resist ink dircetly onto the copperside of a PCB.
> But this would need some special ink (maby just mixing regular ink with
> chemcal would make it Etch resist).
> Some experimentation would be needed and in de worse case you will
> the printhead.
> And Piezo Printheads are expensive to replace as Brad pointed out.
> Ironic as it may be Thermal inktjets often have the printhead intergrated
> into the ink cartrige (HP). This makes them a lot cheaper to replace then
> there piezo coussins but thermal heads need waterbased inks as some folks
> pointed out and those inks would disolve in the Etch bath.
> Drat !
> But what if you printed the INVERTED image of your design onto the copper
> side of the PCB using the regular ink and then coat the whole thing with
> some standaard Etch resist ink.
> Then when you put it in the Etch bath the parts of the board that received
> "normal ink" and a "Etch Resist ink" might let go and only the parts that
> have 1 layer of etch resist would remane .
> Or would the second coat of Etch resist prevent the unlying layer of
> ink" to dissolve in the Etch bath ?
> Maybe this "print and coat" method won't work but maybe some variation on
> or does somebody else have a better idea. Thermal wax ? goodold
> pinhead/ribbon printers ?
> I also took a look at printerhead manufactures and found out that you can
> make a Piezo head printer that can do (somekind of) Etch resist ink. The
> price of these heads and the effort needed to develop en new printer or
> retrofitting and old one would be factors in considering using these kinds
> of heads.
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