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pcb printing

Discussion in 'Electronic Design' started by Michael (Micksa) Slade, Oct 27, 2004.

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  1. Pretty soon I plan to get a bunch of equipment to make PCBs using
    photoresist & laser printed transparencies etc.

    I have the laser printer already, and I did a test to check its
    stretching. I got a graphics prog to draw a square of 15cm or so, and
    measured each side.

    The horizontal side turned out pretty much exact, but the vertical was
    151mm or so.

    Can I work with this? will vertical stretching of the board layout by 7%
    or so cause trouble for me? Or should I look into fixing this printer, or
    getting a new one?

    Can anyone recommend a (not too expensive) printer? Preferrably one
    that's linux-friendly

    Lastly, does anyone have a service manual for a canon LBP-800? :)

    Mick.
     
  2. 7% Is too big to be usable.

    However, 1/150 = 0.7 % ...

    0.7% should be OK for most part, unless you have very fine pitch stuff.
    If the distortion is constant, you can compensate in software. Export in high-res
    image, then shrink it by 0.7% in vertical direction then print.


    Sylvain
     
  3. Blech. Yeah, I guess I could do that, once I figure out how go get the
    program to produce an image...

    I'd prefer to not have to worry about it though. I'm thinking my
    printer's roll speed or whatever could be calibrated and corrected. Hence
    the request for the service manual.

    Mick.
     
  4. Redo your calculation. The stretching is under 0.7% (it is less than 1mm
    in a hundred, so _must_ be less than 1%). As such, it will be fine for
    most things (7%, would be unacceptable).
    It is allmost certainly just because the paper is being bent when printed.
    As such, it will change with the media (are you printing the test, on
    paper, or plastic?).

    Best Wishes
     
  5. Roy Battell

    Roy Battell Guest

    You can probably get the CAD software to do it by settings slightly
    adjusting the scalings separately on the two axes. Its very unlikely
    the printer mechanism will have any adjustment - the rollers will
    be driven by stepper motors and it is the exact diameter of the
    roller that is about 1% out. Much more important is that it is
    consistent across the width than absolutely accurate or you get
    skew, so don't try sanding it down!

    Actually, unless you have some very long connectors in that
    direction I'd not worry about it.

    If you want some Linux CAD that includes size calibration for
    printer/plotter output have a look at
    http://www.vutrax.co.uk (Main UK site for Vutrax CAD)
    or http://www.protonique.com/vutrax (Central Europe Mirror)

    Roy
     
  6. CBarn24050

    CBarn24050 Guest

    Subject: pcb printing
    i woudnt bother with laser prints, not only do you have dimension problems but
    the density isn't good enough for anything but the crudest pcbs. Get a local
    pcb company to do you some photoplots.
     
  7. If it's consistent could you re-scale the artwork to compensate?
    What media are you using - if you're using plastic film of any sort this may be the problem.
    Tracing paper (heavy, >90gsm) is by far the best thing for doing PCB artwork on lasers.
     
  8. ..
    Not true.
    Laser print on tracing paper and decent quality laminate can easily do 40 tracks per inch with no
    defects.
    see www.electricstuff.co.uk/pcbs.html for details
     
  9. 0.7% not 7%. Suppose you have a DIP-40 vertically oriented. That's an
    error of about +/- 0.006" in the hole locations. That's likely not a
    big deal for homemade boards.


    Best regards,
    Spehro Pefhany
     
  10. Leon Heller

    Leon Heller Guest

    I use a LaserJet 5P that I bought cheap on eBay for creating PCB artwork. I
    only make smallish PCBs (biggest has been 100 mm by 160 mm) so distortion
    doesn't really matter, especially as the components tend to be quite small
    these days. The Pulsonix software I use would allow me to adjust the hor.
    and vert. scale if I wanted to.

    Leon
     
  11. I wouldn't bother with all that at all!!!

    Because: Once you got all the chemicals and equipment together you will have
    spent a significant sum of money and a lot of time. It then takes more time
    to get the process right to yield mediocre results. Life is too short.

    Send it off to one of the new small-series print manufacturers that are on
    the net and get a professionally made board back in the mail 1-3 weeks
    later. The sooner, the dearer.

    I don't know where you are - here in Denmark I have had consistently good
    results with PCB-pool; http://www.pcbpool.com .
     
  12. Did you ever upgrade to the full version, Leon? I was wondering if it
    was worth the extra money.
     
  13. Leon Heller

    Leon Heller Guest

    I've used the full version since it first came out. I'm one of their beta
    testers so I get all the optional packages and get to try out each new
    version.

    Leon
     
  14. Leon Heller

    Leon Heller Guest

    I use PCB-Pool, but I often make my own single-sided boards at home. Total
    cost of equipment, chemicals etc. is about 50 GBP (including the printer). I
    can get down to 10 mil tracks or less without any problems and a typical
    board takes about 1 hour.

    Leon

    Leon
     
  15. Leon Heller

    Leon Heller Guest

  16. nospam

    nospam Guest

    Life is too short, but, apparently long enough to wait 1-3 weeks for PCBS.

    I can and have made PCBs in 1 hour. The most expensive parts of the setup
    were a UV light box and a high speed drill + stand both of which have other
    uses.
     
  17. Guest

    Pretty soon I plan to get a bunch of equipment to make PCBs using
    Not everything is life is driven by the almight dollar, or the currency of
    your choice :)

    Some of us like to do things like this for fun, control, education, and often
    it is a lot faster than sending things out to someone else to deal with.

    Not every photographer uses a digital camera and the corner drugstore for
    everything. Many of us still enjoy the darkroom processes and the fulfilment
    of doing it exactly the way we want.

    I use alternative energy to power my home, even tho its certainly not cheaper
    than the local power company.

    Lighten up and realize that some people just enjoy doing the work for the sake
    of the work. Money is not everything, although its seems to be getting
    there......

    John
     
  18. CBarn24050

    CBarn24050 Guest

    Well thats only 12thou traces, which is pretty crude by todays standards.
     
  19. As stated in a previous post, 1-3 weeks is too long for some people. Also
    money isn't the only issue :)

    I really should remember to point at at the outset that I'm doing this for
    fun, not for profit.

    Mick.
     
  20. But entirely adequate for a large proportion of 1- and 2-layer PCBs. Smaller tracks, down to about 8
    thou are actually possible with care. If you need really tiny tracks then use a commercial
    fabricator - chances are that PCBs requiring this density will need too many vias to be viable as a
    non-plated homebrew PCB anyway. Most run-of-the-mill stuff just doesn't need to be that small.
    I have done PCBs with 0.5mm pitch TSOPS on with this method with good results - you tend to need to
    print a few copies and pick the best one.
    For fine stuff, another good option is to get a transparency made by a phototypesetting shop -
    pretty cheap and excellent resolution.
     
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