PCB artwork and dimensional accuracy

[[email protected]]

Recently built a CNC setup for the light drilling of PCBs and thin
aluminum. Thought this would have ended all my drilling needs but as
usual one thing leads to another. Problem now is the accuracy of my
favorite laser printer. I could see there were alignment issues when
making double sided boards using artwork from this printer but the
workaround was simply to compromise with the positioning of each side.
Now it's quite obvious that the drilling setup is much more accurate
than the laser output and holes will not be centered as well as hoped
even after making scaling compromises.

With injet printers the results are near perfect but I hate the artwork
from them. Tried both an Epson 785EPX and 2200 with similar
results....Diagonal lines are just too jagged and octagonal pads looks
like crap for example. These are both photo printers (most seem to be
these days) and I'm wondering whether it's possible to get better
graphics from any type of injet printer? What would be the printers of
choice for excellent dimensional accuracy and fine art detail for less
than $1000.00 or even $2000.00? I'm not even interested in color.

 

[Tim Shoppa]

I'm not even interested in color.

Well, then, stop pricing color inkjet printers.

B/W laserjets are good enough for most double-sided layouts. They
often are consistently off-scale by a percent of so in both X and Y,
but it's a "small matter of software" to correct this if it matters.
1% isn't much for a 16-pin through-hole part (0.007 inches over 8 pins)
but it can matter for a 64-pin LCD module for example (0.063 inches
over 64 pins).

Opacity when printing to transparency material can be an issue if you
do photo-exposure... or do you use toner transfer?

Old pen-plotters are the functional equivalent to your CNC setup and
are real cheap.

Tim.

 

[Matthias Melcher]

With injet printers the results are near perfect but I hate the artwork
from them. Tried both an Epson 785EPX and 2200 with similar
results....Diagonal lines are just too jagged and octagonal pads looks

like crap for example.

That surprises me. Is it possible that you output in a relatively low
resolution, while your inkjet is high res, so it makes the jaggies visible
to begin with? Inkjet printers have easily resolutions of 1440 dpi. My Epson
Stylus R200 cost $50 and is advertised at 5760 x 1440, far beyond my ability
to see. However, if the source image is low res, I will absolutely see the
jaggies on the printout. Maybe you were not printing at highest quality?

Matthias

 

[Ross Herbert]

like crap for example.

That surprises me. Is it possible that you output in a relatively low
resolution, while your inkjet is high res, so it makes the jaggies visible
to begin with? Inkjet printers have easily resolutions of 1440 dpi. My Epson
Stylus R200 cost $50 and is advertised at 5760 x 1440, far beyond my ability
to see. However, if the source image is low res, I will absolutely see the
jaggies on the printout. Maybe you were not printing at highest quality?

Matthias

I agree with you Matthias. I am using an obsolescent Epson Photo
Stylus 700 on a Win XP Pro machine and I can get perfect transparency
prints at 1440 dpi.

Just as an aside, Epson provided drivers for Win2K/XP for this printer
but they were never signed for use on Win XP so Microsoft provided
their own cut down signed driver for this printer. The Microsoft
signed driver does NOT have all the high res settings available in the
Epson driver. Fortunately, you can install the Epson Win2K/XP driver
but you have to ignore the warning XP issues about the unsigned driver
when installing. In Settings/Printers & Faxes there will be 2 Epson
Stylus printers installed - one of them is automatically installed by
XP with the Microsoft driver (shown as Epson Photo Stylus 700 ESC/P2),
and the other will be the manual install with the Epson drivers (shown
as Epson Stylus Photo 700).

Ross

 

[James Meyer]

Recently built a CNC setup for the light drilling of PCBs and thin
aluminum. Thought this would have ended all my drilling needs but as
usual one thing leads to another. Problem now is the accuracy of my
favorite laser printer.

Use a UV laser in your drilling CNC machine in place of the drill bit.
Then you have a gerber plotter with exactly the same resolution, scale factor,
and accuracy as the drill. You'll still need sensitized boards to plot on and
the plotting will have to be done in subdued light, but it should work a treat
after you modify your gerber outputs to match the aperture of the UV laser.

Jim

 

[[email protected]]

I agree with you Matthias

Spoke to Epson yesterday and they recommended the latest drivers and
yes that was the problem. Didn't notice any new high res options in the
menu but the quality is much better now....not on par with the laser,
nevertheless, perfectly acceptable.

 

[Rich Grise]

Recently built a CNC setup for the light drilling of PCBs and thin
aluminum. Thought this would have ended all my drilling needs but as
usual one thing leads to another. Problem now is the accuracy of my
favorite laser printer. I could see there were alignment issues when
making double sided boards using artwork from this printer but the
workaround was simply to compromise with the positioning of each side.
Now it's quite obvious that the drilling setup is much more accurate
than the laser output and holes will not be centered as well as hoped
even after making scaling compromises.

With injet printers the results are near perfect but I hate the artwork
from them. Tried both an Epson 785EPX and 2200 with similar
results....Diagonal lines are just too jagged and octagonal pads looks
like crap for example. These are both photo printers (most seem to be
these days) and I'm wondering whether it's possible to get better
graphics from any type of injet printer? What would be the printers of
choice for excellent dimensional accuracy and fine art detail for less
than $1000.00 or even $2000.00? I'm not even interested in color.

Have you considered chucking a felt-tip pen into your CNC?

Good Luck!
Rich

 

[jim dorey]

Have you considered chucking a felt-tip pen into your CNC?

Good Luck!
Rich

there's a hobby cnc feller that uses a sharpie that way as resist.

 

[[email protected]]

Have you considered chucking a felt-tip pen into your CNC?

Not that desperate. The latest Epson drivers for the 2200 seems to have
solved my problem with the "jaggies". Printing is also now around ten
times faster for the highest resolution than it was before.

 

[Adam. Seychell]

Recently built a CNC setup for the light drilling of PCBs and thin
aluminum. Thought this would have ended all my drilling needs but as
usual one thing leads to another. Problem now is the accuracy of my
favorite laser printer. I could see there were alignment issues when
making double sided boards using artwork from this printer but the
workaround was simply to compromise with the positioning of each side.
Now it's quite obvious that the drilling setup is much more accurate
than the laser output and holes will not be centered as well as hoped
even after making scaling compromises.

With injet printers the results are near perfect but I hate the artwork
from them. Tried both an Epson 785EPX and 2200 with similar
results....Diagonal lines are just too jagged and octagonal pads looks
like crap for example. These are both photo printers (most seem to be
these days) and I'm wondering whether it's possible to get better
graphics from any type of injet printer? What would be the printers of
choice for excellent dimensional accuracy and fine art detail for less
than $1000.00 or even $2000.00? I'm not even interested in color.

Inkjets can be very deceiving if you don't understand that ink and print
media are very dependent on each other. If you buy refill inks then you
have to experiment with different brands of inkjet transparencies until
you find one that works, and/or buy different inks as well. The printer
doesn't need to be expensive. The cheap Epson Stylus and Epson
transparencies are about the best results I've seen. But after lots of
trial and error I found I great results with my bottom of the range
Cannon S330 inkjet with HP or Kodak brand inkjet transparencies with a
particular black pigment based refill ink from a local shop. Artwork
lines and spacing at 0.25mm (10mils) are a no hassle using either of the
above two setups. Results vary enormously between transparencies and
inks, more so than what I am able explain. To make matters more
complicated, the printer driver settings also make a big difference to
quality of the photomask. Printing from incompatible inks/media
typically have problems such as pin holes, poor density, jagged edges
and poor ink absorption. Incompatible inks can also cause pin holes,
jagged edges, splattering and horizontal trails.
I have experimented with about 6 brands of inkjet transparencies, 4
brands of refill inks and 3 inkjet printers.

 

[[email protected]]

Printing from incompatible inks/media

typically have problems such as pin holes, poor density, jagged edges
and poor ink absorption.

None of the inkjets here has a transparency media setting so one has to
choose a media setting that allows the highest resolution to be printed
on transparencies. In other words fool the printer into believing it's
printing on something else. Depending on printer, just choosing any
photopaper media setting may not be the best idea. Any comments on that?