Larry and others,
If you print onto a sheet of plastic with an inkjet and
put it into the acid for us. I am out of acid right now. Let us
know if the inkjet ink holds up! If it does then the idea is
valid. I remember a guy from Texas asking me about printing directly
onto copper. I am overwhelmed with projects right now and it has been
too hot this summer. I burned out trying to finish the Morph!
Cranky
--- In Homebrew_PCBs@y..., "Larry Edington" <ledington@a...> wrote:
> The problem with scratch and etch is the same as milling. Users
must have a toolpath calculation program to
> generate the outline toolpaths. In practical terms, that's
expensive for robust software that can do small trace
> pitches.
>
> Outline paths also have the problem of "islands" of varying sizes
which can cause a lot of problems
> for high speed boards. I don't think you could practically route a
differential trace pair with isolations. There would
> be an enormous amount of rubouts required to clear all the copper
between the traces but keep the traces at the
> proper spacing and width for the correct impedence. One tiny hair
of copper running along between your traces
> can really mess up the signalling. I wouldn't even try an LVDS bus
with isolation.
>
> Sure, Eagle can do outline paths but not everybody uses Eagle. T-
Tech's Isolator Pro does excellent toolpaths
> but is expensive!. KellyCam generates pretty good toolpaths but
sucks as a CNC controller. I always used Isolator
> Pro for toolpaths when I did mechanical etching.
>
> I played around with "scratch and etch" too for a while. I also
plotted directly to copper using modified drafting pens
> filled with acrylic floor polish. The smallest pen I have found
locally is a .18 mm tip technical pen. That produces a trace
> of .0070866 wide. So it's a 7 mil trace. I successfully plotted and
etched some 48 pin TSOP to 48 pin DIP adapter
> boards so I could read some flash roms on my programmer. But it was
SLOW! Also filled areas like pads
> had concentric circles in them where the carbide pen tip scratched
into the just layed down path of resist.
>
> However, using Inkjets produces solid fills with no voids. No
special software is needed either. All you need is
> something that can print your gerber files to a standard printer.
>
> Modern inkjet printers are fast and are accurate enough to do some
very small trace widths and spacings.
>
> You could also lay down solder mask and the component identifiers
using the same modified printer.
>
> While I agree that the scratch and etch idea is great, and has some
benefits over direct resist application, the biggest
> downside I see is the problem of the toolpath generation for the
average user. Also, the tool must be tightly controlled
> to produce the necessary isolation path widths. For me the perfect
width would be a 5 mil tool. But will a tool that is
> .005 wide cut a clean swipe through the bluing without splintered
edges? If your tool has a very sharp tip, then you'll
> need multiple passes to get a 5 to 10 mill isolation path. I never
got a clean enough path through the resist. "furry"
> or jagged edges on traces also cause lots of noise problems on high
speed circuits.
>
> The market for these products are not just hobbiests. There are a
lot of us guys out there that make their living in the
> electronics industry that would LOVE to have something to quickly
make a board without having to send it out!
> Lots of corporations would buy them for the EE labs!
>
> I just wish someone would run with it and work out all the bugs so
I could just buy one. I want to make boards not
> tools to make boards.
>
> later,
> Larry E.
>
>
>
> ----- Original Message -----
> From: crankorgan
> To: Homebrew_PCBs@y...
> Sent: Saturday, September 14, 2002 6:41 AM
> Subject: [Homebrew_PCBs] Re: Inkjet printing PC boards
>
>
> 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]
>
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