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After wasting money, I learned that I can develop and etch PCBs but the artwork is a problem.

Today I bought premium transparencies (made by MG chemicals) specifically for laser printers. I own a brother laser printer.

I did two printouts and made use of the full page as I am doing multiple circuits in one go.

I tried thick paper setting, and the printer took time to print. I tried thin paper setting and the printer printed super fast. In both tests, the image seem to have shrunk horizontally by a few percent (I couldn't align a 40-pin DIP IC onto the holes in the mask and my circuit requires a 40-pin DIP IC).

In the past I tried vellum (equivalent to 120gsm tracing paper), and it also does not work for large circuit boards because the result is not solid (PCB in the end looked patchy and the only way to use it was to redo the board with solder tape?).

I did read somewhere about transparencies shrinking when going through a laser printer but I wasn't expecting MG chemicals transparencies (that even indicate online they are heat stabilized) to shrink the image.

Yes I have done the obvious of making sure I'm printing at a 1:1 scale and I didn't do anything in software to cause scaling to happen.

It seems that my only options are these:

  1. Run to a print shop for every printout (which is a pain).

  2. Ditch my printer and find an older one.

If I choose option 2, should I go with inkjet or laser and why? and what brand should I go for?

The thinnest track width for all my boards is 10mil.

EDIT: I increased the margins to make the printer driver happy but I still get the same disappointing results of the image not to scale.

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Printers are not necessarily made to print in super precision.

Maybe your software has a scaling adjustment (different in X and Y, hopefully). Just put some reference marks of known separation on your artwork and fiddle with it until they measure exactly what they are supposed to measure.

Do that in both X and Y dimensions.

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  • \$\begingroup\$ I notice this more on transparencies than any other media. I don't get it. \$\endgroup\$ – user143136 Mar 23 '17 at 20:28
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    \$\begingroup\$ Maybe the transparencies slip in the rollers. The accuracy in the X direction is fixed by the printer (LED type 'laser class' printers will be very, very accurate), but lengthwise it depends on the printer feed mechanism. \$\endgroup\$ – Spehro Pefhany Mar 23 '17 at 20:29
  • \$\begingroup\$ You can minimize the consequences, if this is the case, by orienting your artwork so that the critical dimension is horizontal. A 5% error in the 0.6" width of a DIP 40 only requires splaying the leads by 30 mils each, but in the long dimension 5% is an entire pin pitch over the length of the DIP. \$\endgroup\$ – Spehro Pefhany Mar 23 '17 at 20:40
  • \$\begingroup\$ For "quality control" consider including multiple fiducial marks of known size and position, in every design layer, every job. This way you can check for dimensional creep at every stage, and catch if it gets too far. (Maybe the print rollers wear, or a different batch of film is more slick) \$\endgroup\$ – MarkU Mar 23 '17 at 20:53
  • \$\begingroup\$ MarkU, I literally tried fitting one side of an IC onto the art to see if the pads line up with the IC pins and with my tests they did not. Now I'm starting to wonder if my software shifted things because I wanted 1mm margins instead of 0.5inch margins. \$\endgroup\$ – user143136 Mar 23 '17 at 21:34
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Switch to Inkjet

Inkjet's print on transparency film better than lasers because they don't heat the film significantly.

Calibrate the feed rate

Many printers have advanced (sometime hidden) menu options to finely tune the paper uptake (feed) rate and thereby calibrate the length dimension. Here's an example for one model of printer.

Compensate via software

If the error is stable enough, pre-scale (pre-emphasize) in the printer driver or with your application to compensate for the resulting shrinkage

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  • \$\begingroup\$ I'm trying the compensate method by making a smaller PCB to fit within the margins the printer driver wants to use. Before eagle asked me whether I wanted to use my margins or the printers margins and I told it to use mine (of 1mm all the way around). I'm going to try to accept the drivers margins and see what happens. \$\endgroup\$ – user143136 Mar 23 '17 at 21:37
  • \$\begingroup\$ The printer can't physically work with a 1mm margin. If you do that the behavior is unpredictable. \$\endgroup\$ – DrFriedParts Mar 23 '17 at 22:24

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