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The Gootee method

Discussion in 'Hobby Electronics' started by [email protected], Feb 3, 2007.

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  1. Guest

    No, it isn't a birth-control thing, it's a 'ghetto' method of using a
    laser printer to create iron-on toner resist to PCB boards.

    See: http://www.fullnet.com/~tomg/gooteepc.htm

    Thought I'd give it a go last weekend, and not having the 'special'
    Staples #471861 paper on hand tried using an Epson glossy inkjet
    'photo'.

    The results were - to put it mildly, a fair bit less than expected.
    The exploding air bubbles between the backing paper producing some
    'interesting' audio and visual effects which I think maybe I can now
    file under my 'impressionist' period in art <g>.

    The question. Has anyone had success with this method, does it involve
    using less than 10 expletives, and what sort of paper did you use?

    I've since ordered some - expensive I think - Peel 'N' Stick from
    Jaycar as a backup...

    Cheers, Phil.
     
  2. Guest

    Thought I might pre-empt any correction from you guys on my post.
    Yes, I know that the expression 'PCB boards' is probably-bably
    something like a 'double additive' (WTF the correct term is I dunno).
    Anyway, thought I'd get in first to correct myself...
     
  3. Glenn

    Glenn Guest

    I don't know what others are using, but I a photoresist board. I used
    negative resist Riston for quite a few years. It's very tough and
    reliable, but a pain to create the negative image for exposure. I now
    use a positive resist board (Kinsten), which is fairly delicate but
    works extremely well. And how do I do my positives? Simple. I just
    laser print onto transpareny film. I do two identical copies and
    sticky tape them together to give a good density. I then expose with
    a high power (800 W) halogen which has enough UV in it to do the job.

    I get excellent results with this method, and its quick and simple.

    What are others doing?

    Cheers
    Glenn
     
  4. Mr.T

    Mr.T Guest

    Yes, I would have thought it fairly obvious that PCB board is a tautology.
    It seems logical to use either the full term Printed Circuit Board, the
    acronym PCB, or if you really must hybridise it, then "PC board" is fairly
    straight forward surely?

    MrT.
     
  5. Robbo

    Robbo Guest

    My set up:

    Kinsten board, single transparency printed on a cheap laser printer. I
    adjust print properties for higher contrast & sharpness - this may not be an
    option on all printers.

    Expose using 2 x 10" or so UV fluoro's mounted in a box + glass. Exposure
    time is 90 seconds. I use a bit of neoprene rubber (like wetsuit material)
    and a lump of aluminium to hold it down against the glass. Its pretty
    reliable for 8 or 10 thou tracks with 10 or 12 spacing.

    It's sometimes a little inconsistent - I think the transparency may not
    always sit flush against the board. ammonium persulphate etch in a homebrew
    polycarbonate tank with a fish tank heater - it runs at about 42C and etches
    in 5 or 10 minutes.

    For DS boards I just tape transparencies together then expose one side, then
    the other.

    r.
     
  6. For prototype single sided boards I use www.pcbcart.com
    For double sided boards I use www.pcbcart.com

    For small production runs, I use... www.pcbcart.com

    I know I know, its not as satisfying when you pay someone to make your
    boards for you, but eh, their quality is very good, and electronic testing
    of every board is standard, so if you need the board done, and want to
    concentrate more on electronics than chemistry or art and craft, you may as
    well use em.
     
  7. Robbo

    Robbo Guest

    True Phil - for me it depends on the lots of factors - do I only want one or
    two boards, is it a simple board, am I going to hack it severely during
    development? Commercially made boards seem to be getting cheaper and the
    quality/presentation is miles better than home brew boards. Home brew boards
    does howeveer mean I can have a proto in my hand in an hour or so. I'm not
    sure I could be bothered with toner xfer/peel n stick though.
    r.
     
  8. Guest

    Thanks Phil (in Melbourne).

    The prices look good!

    I'm not confident enough with Eagle layout yet and think any file I
    send may be totally wrong. I'm guessing some things will be lost in
    translation, although I may just try it anyway.

    Also, I'm still deliberating over decoupling and EMI protection, so
    that's gonna take some time sorting out.
     
  9. Guest

    Sorry about dredging-up such an old thread (I saw my name mentioned,
    while doing a search). But this might be useful:

    To see whether or not your PCB's Gerber files and layout, etc, are
    acceptable to a PCB manufacturer, I highly-recommend trying http://www.freedfm.com
    , which is also available via the "FreeDFM" link at http://www.4pcb.com
    , on Advanced Circuits' website. (In this case, DFM stands for Design
    For Manufacturability, IIRC.)

    The freeDFM facility takes your uploaded ZIPped Gerber file set (which
    might need to be in "Extended" Gerber 274-X format, IIRC) and does a
    number of automatic tests to try to determine if the board will be
    manufacturable, or if there are any other problems. It then
    automatically emails you a report that includes lists of "possible
    show stoppers", and other errors, with five samples of each type of
    error.

    For each error sample, it gives the coordinates, the error's
    measurement/margin, and drawings with three different zoom-views of
    the error's location. ALSO included in the resulting email are PDF
    files with high-resolution drawings of your Gerber files' layouts
    (essentially an on-line free Gerber file viewer). They also include
    their price quotes, etc, of course.

    You don't need to worry, much, in advance, about the Gerber filenames
    and what they correspond to (although I think that they do require DOS-
    style naming, i.e. 8 characters max, and then a 3-char extension),
    because their software will immediately list all of your uploaded
    files and let you pick from a drop-down list, for each one, to tell it
    which PCB layer or other file-type each one is. (But they do also
    have a list, there, somewhere, of the standard Gerber file naming
    conventions, for several popular PCB layout software packages.)

    The FreeDFM utility seems to be quite good, and very useful, and
    probably saves their customers and their CAM engineers a ton of time!
    I've also used Advanced Circuits to have PCBs made, and have been
    extremely satisfied with their work and service, but especially liked
    the almost-painless aspect that their freeDFM and automated ordering
    system enabled me to experience as a first-timer. Since you're in
    Australia, you'll almost-no-doubt be better-off finding a more-local
    manufacturer. But at least you can still use the freeDFM service,
    first, and be able to be more-confident when initiating contact with a
    PCB manufacturer, especially for the first time.

    One detail: If you can set your Gerber "device setup" options to
    include "Hardware Fill", it might help to avoid "nuisance" errors
    related to tracks being too narrow, since, otherwise, poured copper
    areas might be filled with lines, instead of being "solid", and the
    lines might be mis-interpreted as tracks. I did have that happen,
    once, when I first tried freeDFM, but, weirdly, only for a small
    portion of my poured copper areas, and never could figure out exactly
    why it happened for some poured areas but not for most of them. Oddly-
    spaced lines could actually be seen in the "problem areas", in the
    PDFs of the Gerbers that they sent back, if they were magnified above
    something like 1200x. But, it's better to use "Hardware Fill", anyway
    (and "Hardware Arcs"), since the results will be more-accurately
    rendered, and the Gerber files will be smaller (assuming you have used
    any copper pours, or arcs).

    Regarding your deliberations over decoupling and EMI protection, etc:
    Those are huge subjects (and are usually well-worth deliberating
    over). And I'm no expert. For PCB layout design, apparently a lot
    depends on the edge-times of the signals involved (i.e. not
    necessarily their frequency, per se). There are some truly-great
    appnotes (Application Notes) covering those types of considerations,
    at places like Analog Devices' website, http://www.analog.com , as
    well as at other IC manufacturers' sites (e.g. national.com,
    linear.com, et al). I can come up with some specific ones that I
    think are very good, if you think you don't already have enough of
    them. The entire Walt Jung book, "Op Amp Applications Handbook", is
    on line, at analog.com, too. That book, also, has a pretty good
    section that deals with those topics. For what it's worth, I usually
    try to include RF filtering on almost all system inputs, outputs, and
    power rails, and on most opamp inputs, and on all opamp power pins
    (and wherever else it seems like it might be necessary).

    Spice programs (e.g. LT-Spice, the _excellent_ free one from
    linear.com) can actually be very useful (and enlightening), for
    modeling and simulating a lot of the problems that can occur with
    improper grounding schemes, and EMI/RF stuff. But you have to insert
    the proper impedances into the models, e.g. PCB traces' and wires'
    impedances. At the very least, if you model the inductance and
    resistance of your power, ground, and signal traces (and capacitance,
    if using a ground plane), it's pretty easy to see what happens when a
    ground trace (for example) is shared, that shouldn't be shared. It
    can also sometimes be quite eye-opening to add parasitics to the
    component models, i.e. parallel capacitance across resistors and
    series inductance for capacitors.

    Sorry to have blathered-on, for so long, about all of that.

    Good luck!

    - Tom Gootee

    http://www.fullnet.com/~tomg/index.html

    -
     
  10. Guest

    Well, ahem, I'VE had pretty-good success, with that method.

    I used the recommended paper, having tried many other types, mostly
    with poor results, although there are quite a few that are "almost as
    good". And I usually only have to use 8 or 9 expletives.

    All kidding aside, though, the toner-transfer method CAN work
    extremely well, and can be almost painlessly easy and quick. It might
    take an hour or two of practice, at first, to get to that point,
    though. I tried to give as many details as possible, in hopes that
    the "practice" time would be minimal (and, mainly, so people wouldn't
    have to "re-invent the wheels" that I had to, i.e. just to try to save
    "the universe" some time and trouble). But at least you can usually
    just wash the toner off with acetone or laquer thinner, and start
    over, wasting mostly only some time.

    For making "immediately-available" prototype boards without much
    special equipment or money, it's pretty hard to beat.

    By the way, there's a LOT of good information available about
    different ways to make PCBs, yourself, in the Homebrew_PCBs discussion
    group, and its archive, at http://www.yahoogroups.com . [Not too long
    ago, there, I read about some guys who have successfully modified a
    couple of different inkjet printer models to use certain types of ink
    to DIRECTLY print the patterns onto PCBs. i.e. They can now run the
    boards right through the inkjet printers. (Talk about painless! I
    think I just might have to try that!)]

    Good luck!

    - Tom Gootee

    http://www.fullnet.com/~tomg/index.html

    -
     
  11. Guest

    Hey Tom,

    Thanks very much for taking the time to write, also for the great
    amount of information. I feel kinda honoured.
    I've still yet to get back to using your PCB method, and now having
    read more know of at least one other problem apart from paper
    selection, iron temperature.
    I had the temp set to max, which is probably great if you wish to
    create exploding air bubbles.

    Also, thanks for the links, especially regarding decoupling and EMI
    protection.
    I guess you understand why I stopped for a good long think at that
    point.

    I'll give freeDFM a try also this week. Looks like it will help a lot.

    I'm a little embarrassed though that you've probably been reading
    other aus.electronics subjects. Trying not to go into specifics let me
    just say that we Aussies don't normally swear at each other and I've
    only ever had help, even from the person/s that may be going a fair
    bit overboard in that area.

    BTW, we have an Australian electronics magazine http://www.siliconchip.com.au/
    (the only one in captivity here) which I'd like to see an article in
    about your PCB method. Not sure if they - or yourself for that matter
    would be interested, but if anyone noticing this message might be in
    contact with SC (maybe Leo), it may be worth mentioning.

    Anyway, thanks again for the help.

    Cheers, Phil.
     
  12. Guest

    [Phil: I've tried posting replies, repeatedly, through Google Groups
    (http://groups.google.com ), but have not seen my messages appear.
    This is another try, but in response to my own message, instead.]

    You're welcome. No problem. And thanks.

    Gee, that's almost embarrassing. I'm just a regular guy; dumber than
    some but more stubborn than most. :)
    Actually, I use my iron at max temp, too. But I haven't measured its
    actual temperature. Someone also said that a lower temp might make
    the paper release better, after the transfer. The type of paper is
    probably the most critical factor. I'm not sure what kind of bubbling
    you had. I always get a sort-of bubbling effect when soaking the
    board, to get the paper to release. But none has ever exploded. If
    it's happening during the ironing step, maybe you should try baking
    the paper in an oven, first (before printing the pattern onto it). I
    suppose you could also get bubbling if the PCB surface had traces of
    acetone or some other liquid, remaining on it. Maybe you should try
    baking the blank cleaned/prepared PCB, first, too, or even just
    preheating the bare board with the iron (maybe with a clean sheet of
    plain paper on it to keep the surface clean), just to be sure, (and
    then let it cool somewhat) before putting the pattern paper on it.
    Oh yeah. It's definitely not trivial. And it can be quite a pain,
    especially if you find out you did it wrong AFTER already doing a lot
    of work on a layout.
    Don't sweat it.

    Apparently I haven't read enough of them. But since you've "spilled
    the beans" preemptively, I probably will have to go have a look,
    now. :)
    I'm always glad to help. It's one of my many character flaws. :)

    Good luck!

    - Tom Gootee

    http://www.fullnet.com/~tomg/index.html

    -
     
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