I'm not so sure that a 7 mil trace is going to come out that well on
a 300 dpi device. that is basically 2 dots wide (2.1 to be exact but
it doesn't do partial dots). that isn't very much toner. 10 mils is 3
dots and that's still kind of light.
Also, I'm not sure its a unit conversion problem. 300 dpi means each
dot is 3.33 mils wide (or .3 dots/mil). You dont get exact alignment
except on 10 dot/3 mil boundaries (for whole mil alignment). So, for
example, a 7 mil trace width starting at 5 mils will have .5 dot, 1
dot, .6 dot (in a row). Depending on how the printer driver software
handles this you could get 1, 2 or 3 dots. if three, you've got a 10
mil trace, if 2, you've got a 6.66 mil trace. Using metric, you can
see similar alignment issues though the math is messier. I know
later HP printers do some sort of resolution enhancement so there are
probably more subtle issues but I always turn that stuff off.
Bottom (and quite obvious) line: you need more DPI for better
printing of your artwork. I'd skip 600 and get a 1200 DPI printer.
--- In
Homebrew_PCBs@yahoogroups.com, Stefan Trethan
<stefan_trethan@g...> wrote:
>
> > A cheap old epson stylus 400 colour will do 8mil tracks/spacing
smoothly
> > in
> > 600x720dpi mode. It's the printer technology and ink/transparency
> > combination
> > that makes the most difference.
> >
> >
>
> You don't understand the problem.
> Even a 300dpi unit can do traces of 7 mil but _not_ metric spaced
smd
> parts.
> the printer works in inches and if you print metric spacing you get
a
> variations in
> line width and space.
>
> ST