Homebrew PCBs

Larry,
      I sell plans for a PCBmill (Brute) and I just finished a 
machine that will mill or draw simple boards. (Morph)
      Months ago I brought up the idea of Scratch and Etch. This
idea is not dead. First I developed a super simple CNC plotter. Now
I have a machine strong enough to drag a scribe through the blueing.
Several people tried Scratch and Etch With good results. Coating the 
whole board and then scribing and isolation between pads for etching 
seems easier.

                                           Crankorgan John 


--- In Homebrew_PCBs@y..., "Larry Edington" <ledington@a...> wrote:
> 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.
> 
> 
> [Non-text portions of this message have been removed]