PCB artwork and dimensional accuracy

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.

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.

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

On 27 Jun 2005 07:51:01 -0700, snipped-for-privacy@hotmail.com wroth:

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

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.

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

Good Luck! Rich

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.

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

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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.

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?