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Subject: Re: [Homebrew_PCBs] Re: printer limitations or etch undercut

From: Adam Seychell <a_seychell@...>
Date: 2007-04-11

Andrew wrote:
>
>
> Does the Epson peizo print head have less
> scatter of dots than the Canon Adam uses ?
> Your photos of the 6/6 artwork certainly
> look less jaggy than Adams.

Unfortunately all inkjet printers seem to suffer the same problem. Since
its invisible to the naked eye , printer manufactures are unlikely to
bother improving it. All that is needed is to slow the print head by 10
times. You may wait 5 minutes for a printout, but who cares ? I can't
think of any applications other than for hobby PCBs. Professional screen
printers who use inkjet printer transparencies for photomasks don't even
need that accuracy and any PCB manufacture will use a laser photoplotter
(3000+ dpi). So the marketers of inkjet printer manufactures aren't
going to get any calls from customers demanding reduced line edge
jaggedness.

If your interested, I can send you similar images produced from an Epson
Stylus 660 printer.

> In my case the bubble etcher will fully
> etch a stripe down one side of a board in
> 1/2 the time it takes the middle of the
> board to etch.
>

This agrees with my experience with bubble etching too. For really fine
lines, such large etch non-uniformity is unacceptable. Another thing to
note is Derek's test pieces had 6 mil spacing between 6 mil lines. I bet
if one of those 6 mil lines were far away from surrounding copper then
it will get etched faster, and therefore more undercut.

Adam