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pcb etching

Discussion in 'Electronic Design' started by Darkage, Sep 2, 2003.

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  1. Darkage

    Darkage Guest

    whats the best method for etching own boards. Using UV and a riston board
    or the iron on stuff that you use with copper boards.
     
  2. db

    db Guest

    Just this weekend I did up a small board with a 22 pin fpc connector
    with .5 mm pitch and .125mm spacing between pins.
    I used press n peel, an hp 1300 laser printer (1200x1200 dpi) and a
    GBC Heatseal H200 laminator. You will need to pass the board through
    the laminator multiple times so that the board heats up enough for the
    toner to stick to the copper.
     
  3. Darkage

    Darkage Guest

    I like the idea of the press n peel material. I dont have a laminator. Do
    you still get good results with a iron?
     
  4. db

    db Guest

    The iron worked fine while I was doing some basic experimenting with
    some
    boards about 1in x 1in with smds in the 0805 and sot23 size range.
    Even then I got some toner spreading of the traces and pads, but not
    too bad.
    The board I did this weekend was about 1.5 x 3.5 inches and I
    discovered the iron did not provide enough even heat and pressure to
    get the results I was looking for. Some spots would overheat and smear
    while other spots would not stick at all.
    If you are just getting started you might take a look at
    dynaart.com. They sell what appears to be the same laminator I bought
    plus they throw in some transfer paper. I do question the 6in/second
    they have printed for the laminator. Mine went more like 6 seconds per
    inch, assuming it is the exact same model.
    I have not tried it yet, but I think with double sided boards there
    will be better control of registration with the laminator than an
    iron.
     
  5. mike

    mike Guest

    Chuck the pen in the plotter and plot the gerber file. Not messy at
    all. And if you like it and want another, you just chuck the pen in the
    plotter and plot the gerber file. All you need is an old flatbed plotter.

    You want messy, try building a dark room so you can expose and develop
    light sensitive stuff. Or trying to soak the backing off an iron-on
    transfer.



    --
    Bunch of stuff For Sale and Wanted at the link below.
    laptops and parts Test Equipment
    4in/400Wout ham linear amp.
    Honda CB-125S
    400cc Dirt Bike 2003 miles $450
    Police Scanner, Color LCD overhead projector
    Tek 2465 $800, ham radio, 30pS pulser
    Tektronix Concept Books, spot welding head...
    http://www.geocities.com/SiliconValley/Monitor/4710/
     
  6. Darkage

    Darkage Guest

    ahhhhh! now theres an idea :) dont have a flatbed plotter but have came
    across a home made plotter design using stepping motors :) hmm
     
  7. Active8

    Active8 Guest

    man, you don't want to do a whole lot of pnp. you'll be scrubbing with
    acetone forever. it's hard to get good even pressure with a regular iron
    on anything over maybe 3 or 4 " . you have to get the tip down into it
    and all.

    i like the laminator idea, but for more than a coupla boards quick, i'd
    rather use that laminator for dry-film resist.

    mike
     
  8. Active8

    Active8 Guest

    so how fine can you get with a resist pen? i'd just as soon do that, but
    never really got into resist pens. just sharpies. i bet resist ink in a
    regular plot pen would be nice. there was some discussion about that a
    while back.

    mike
     
  9. mike

    mike Guest

    The discussion of pens rages periodically. At one point the
    recommendation was for the Staedtler Lumocolor 318-2. I tried it and it
    seems to work. Some people think the red ones are the best, so that's
    what I tried.
    I also had good plotting results with the finest point sharpies, but
    the ink tended to soften in the etch.

    As for fine lines, you can do as fine as the pen you get, that depends
    on a lot of things. I can get one trace between 0.1" pads, but the pads
    become so small that it's hard to drill 'em without taking out the
    attached trace.

    Then there's the mush factor. You start out with a sharp pen, but all
    that up/down banging from the plotter mushes the tip out so the trace
    gets wider as you go. Finer pens mush more.

    Then there's the drag factor. You put down a pad. Later the pen draws
    thru that pad on it's way to somewhere else. The ink ain't yet
    dry, so a chunk of gunk can get dragged along with the pen making a real
    mess.

    I prefer .020 traces and very slow plotting speed.

    Staedtler makes another ink 485-23SAR-9. Apparently
    it's so toxic that you can't even buy it in the US. But
    you can import it from Canada. That stuff worked really great in a
    metal-tipped plotter pen. Problem was that it ate thru the plastic
    parts of the pen and really gummed up the little wire that goes thru
    the point. Didn't take me long to determine that I didn't want to buy
    a new plotter pen for every board. The sharp tip also had a bad drag
    factor.

    mike

    --
    Bunch of stuff For Sale and Wanted at the link below.
    laptops and parts Test Equipment
    4in/400Wout ham linear amp.
    Honda CB-125S
    400cc Dirt Bike 2003 miles $450
    Police Scanner, Color LCD overhead projector
    Tek 2465 $800, ham radio, 30pS pulser
    Tektronix Concept Books, spot welding head...
    http://www.geocities.com/SiliconValley/Monitor/4710/
     
  10. Quack

    Quack Guest

    I am using PNP-Blue (dry) transfer with a standard house iron and it
    turns out fine. I recently did some tiny SM components on these
    boards, and the small tracks did smudge a *little* but nothing that
    cant be fixed up with a knife & resist pen before etching ...

    Good for prototyping ..

    I like the laminator idea though ... might give it a try if i can find
    a cheap one :)

    Alex.

     
  11. PJ

    PJ Guest

    Stuff snipped..........
    It is available at Galco. $50 min order though....Paul

    http://www.galco.com/scripts/cgiip....arch-part=485 23SAR-9&search-name=WIELAND INC
     
  12. Jim Thompson

    Jim Thompson Guest

    On Fri, 05 Sep 2003 03:37:07 GMT, Active8

    [snip]
    I have a rather expensive laminator that I use to make flash cards for
    my autistic grandson. What is dry film resist?

    ...Jim Thompson
     
  13. That's what's used in most commercial PCB fabrication except at the
    very low end of single-sided boards which are still silk-screen
    printed. The commercial laminators are used in safe-light rooms and
    take a roll of film at a time.

    Here's a relatively small laminator they say is suitable:
    http://www.thinktink.com/stack/volumes/voli/store/specs/modulam.htm
    http://www.thinktink.com/stack/volumes/volvi/modulam_lam.htm

    And a source for the film itself in less than full rolls.

    http://www.thinktink.com/stack/volumes/voli/store/specs/m115spec.htm
    <http://www.thinktink.com/cgi-bin/cart.pl?db|photopolymers.dat|Photoresist>

    The biggest problem with using a paper laminator would probably be the
    adjustment range for thickness. Also, some cheap laminators are "cold"
    (pressure only) and wouldn't work.

    The hassles and cost of legally getting rid of plating and etching
    wastewater is so high that I'd prefer to use commericial suppliers
    except for the very odd one-off. The treatment facility of one local
    medium sized (a few hundred people) PCB manufacturer cost >$2M.

    Best regards,
    Spehro Pefhany
     
  14. Jim Thompson

    Jim Thompson Guest

    My daughter just returned the laminator. It's an IBICO EL-12, accepts
    up to 1/6" thickness (how's that for a strange number?). Temperature
    setting is 100°C to 140°C. No speed adjustment, timed it looks like
    about 0.5"/second. What does PnP Blue or the dry film require?

    ...Jim Thompson
     
  15. Active8

    Active8 Guest

    [snip]
    around 110°C for dry film. not sure about PnP you might take a temp
    probe to an iron on the linen setting to get an idea.

    if it was you who mentioned spray resist, tell me about that. how fine
    and accurate could you go? i was told that the reason presensitized
    boards sell, is because the spray thickness isn't uniform and needs to
    be centrifuged.

    brs,
    mike
     
  16. Jim Thompson

    Jim Thompson Guest

    I wasn't the one who mentioned spray resist, but I did use it in my
    distant past. Worked just fine. I'm just looking for less mess...
    I'll probably send mine out ;-)

    (I once messed up an oven with FeCl3... made me persona non grata in
    the kitchen ;-)

    ...Jim Thompson
     
  17. AtPCLogic

    AtPCLogic Guest

    The biggest problem with using a paper laminator would probably be the
    Its more a problem with the fuser than the transfer paper. The fusing
    temperature of your toner will vary from printer to printer because the toner
    characteristics are optimized for specific print engines. The combination of
    time-temperature-pressure is the most important thing. Experiment....
    Regards,
    Brad
    PC Logic

    Schematic entry and PCB design software
    http://www.pclogic.biz
    http://members.aol.com/atpclogic/index.html
     
  18. db

    db Guest


    The package of PNP says a temperature range of 275F to 325F. So 140C
    just barely makes it at 284F. The temperature needed may depend more
    on the properties of the toner. Also it is possible if the board goes
    through multiple times it may get hotter than the 140C.
     
  19. Michael

    Michael Guest


    Might have been me who mentioned spray resist. I used it many, many
    moons ago ... like the late 60's. I haven't seen it for nearly that
    long though. ISTR the stuff I used was made by G&C (GC?) but I wouldn't
    bet on it. It had a purple color - you could see where it sprayed,
    where it didn't, and how thick a coating was building up. You'd lay the
    board flat, spray it, then bake to dry the resist. I was in the Air
    Force at the time, lived in a barracks, so used ingenuity for the baking
    part: small space heater; board on top; metal waste basket inverted over
    space heater. It "worked a treat" as the Brits say.
     
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