Connect with us

PCBs on glass

Discussion in 'Electronic Design' started by Michael Brown, Jan 6, 2007.

Scroll to continue with content
  1. Possibly slightly odd question here - I'd like to use glass (as in the stuff
    you have in windows, not fibreglass) as a PCB substrate, approximately A5
    (210x150 mm) sized. As far as I can see, there's three options. The first is
    to stick some copper foil on, the second option would be to evaporate copper
    onto the glass, and the final option would be to use electrolysis.
    Afterwards I'd do the usual photoresist/etch steps to get a PCB. I can't
    seem to find much information at all on any of these. The main things I'm
    looking for are surface preparation tips, and things to avoid due to them
    reacting badly with the photoresist.

    One thing that makes it slightly more complicated is that the glass must
    remain transparent (outside of the tracks). Roughing the surface will
    probably be OK as I'm going to be using an optical epoxy to sandwich the PCB
    side (with SMT components) to another piece of glass, but I don't want the
    copper to bleed into the glass (which would presumably result in a green
    tint).

    Any tips/links appreciated, or if anyone knows where pre-coated glass can be
    obtained from in Australia let me know.
     
  2. Rich Grise

    Rich Grise Guest

    If the copper part doesn't have to be transparent, just stick the foil
    onto the glass and etch it or use a press-n-peel premade copper pattern.

    Otherwise, if it needs to be transparent, then you're getting into vapor
    deposition and molecular-beam epitaxy and stuff like that.

    But somebody's got transparent conductive stuff (like the touch-screen
    folks), but you'd have to look that up. )-;

    Maybe http://www.google.com/search?q=transparent-conductor or similar.

    Good Luck!
    Rich
     
  3. Guest

    Actually, printed wiring on glass is a known technology;
    porcelain-on-steel
    circuit boards and additive copper (silk screen applied, I believe,
    possibly
    electroplated to add thickness) is a rugged-duty standard. Last time I
    saw
    it used, was for relays (too heavy for a flimsy plastic board).

    As far as adhesion is concerned, the porcelain is just a kind of glass.

    Surface mount soldering to such a board, however, may require some
    finesse.
     
  4. Guest

    Actually, printed wiring on glass is a known technology;
    porcelain-on-steel
    circuit boards and additive copper (silk screen applied, I believe,
    possibly
    electroplated to add thickness) is a rugged-duty standard. Last time I
    saw
    it used, was for relays (too heavy for a flimsy plastic board).

    As far as adhesion is concerned, the porcelain is just a kind of glass.

    Surface mount soldering to such a board, however, may require some
    finesse.
     
  5. Ben Jackson

    Ben Jackson Guest

    You could look into how the astronomy guys silver home-made mirrors.
    I know I've seen at least one do-it-yourself vacuum deposition project
    on the web. There are also chemical methods, but I'm not sure how
    the chemistry would transfer over to copper.
     
  6. Ian Bell

    Ian Bell Guest

    Actually there's a fourth - silk screen silver loaded epoxy (conductive ink)
    directly onto the glass. I did this over 20 years ago on a coke can and the
    front of Electronics Weekly. I framed the mag with a working flashing LED
    circuit and sent it to the mag. Got an article and interview out of it. 3D
    circuits were all the rage then but nothing came of it.

    ian
     
  7. Ban

    Ban Guest

    Come out of the PCB thinking.
    Take a glass used for solar-panels, print(silkscreen) silver paste on it,
    cure it at high temperature. Have a look at Hybrid manufaction for the
    paste.
    Probably the epoxy will tear off the components due to different thermal
    expansion. it is actually a big problem to even find some suitable backside
    coating for solar panels, let alone hard and transparent stuff.
    Schott, Germany
     
  8. Tam/WB2TT

    Tam/WB2TT Guest

    How are you going to make the holes in the glass? Feedthroughs, crossovers,
    etc.

    Tam
     
  9. John  Larkin

    John Larkin Guest

    Could you use transparent flex pc boards? That's a very common thing.
    They even come with peel-off adhesive, so you could just slap it down
    on the other piece of glass. Multilayers with vias are standard.

    John
     
  10. Chris Jones

    Chris Jones Guest

    What do you need it for?

    If you can stick a normal but very thin fibreglass PCB to the glass I would
    expect that to be most convenient. If you really need to metallise the
    glass, and if you can afford to have this done professionally then it might
    be worth asking Lintek (http://www.lintek.com.au/) whether they would do
    this, as their PCB process is based on vacuum deposition.

    Chris Jones
     
  11. Ross Herbert

    Ross Herbert Guest

    No matter how you might manage to get conductive traces onto the glass
    substrate there is a slight problem when trying to make connections to
    items which require soldering. In my experience glass doesn't take too
    kindly to sudden and localised heating as you would get from a
    soldering iron. Then there is the problem if you need holes in the
    glass...

    Now ceramic substrate is a different matter, and this is used in
    specific circumstances. I would forget about glass if I were you and
    go for a more commonly used method which will work and will be far
    cheaper.
     
  12. jasen

    jasen Guest

    I've never managed to damage it that way, OTOH could always use a
    reflow oven, or hot air.

    IIRC I've see spade lugs soldered to rear window demisters.
    the mirror guys know how to do that, and I've seem the windscreen
    repairers do small holes.

    Bye.
    Jasen
     
  13. Ross Herbert

    Ross Herbert Guest


    You seem to have it all sorted out, go for it!

    Specialised glass - no doubt with pre-cut shape & size (bugger! I
    should have made that a bit smaller, now it won't fit the case)
    Specialised technique for applying conductive material.
    Specialised techniques for attaching connections.
    Specialised hole drilling.

    All in all, just the sort of facilities one would have available in a
    small scale electronics production workshop.

    Oh, did you say you would get these things done by outside
    contractors?

    I wonder how interested a company would be (ie. one which might have
    similar facilities to those which make car windscreens with heated
    wiring and connectors attached) would be in your project. "Sure, we
    can rejig our equipment which is set up to make windscreens to
    manufacture your non-standard clear glass circuit mounting substrate -
    how many millions do you want?"

    Bye.
     
  14. Pyrex?

    Its probably worthwhile investigating the different types of glass
    available and their properties.
     

  15. Using glass for a PC board is nothing new. It was done in the '70s
    for CATV notch filter traps for pay TV. Any attempt to open the filter
    caused a sharp steel spring to shatter the glass, in an attempt to keep
    it from being reverse engineered.


    --
    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
     
  16. Maybe a borosilicate glass (pyrex) that's silvered and then etched?
    Or more likely have copper evapourated onto it as a mirror.
    Won't carry much current in the traces but maybe OK low low frequency cmos


    --
    Dirk

    http://www.onetribe.me.uk - The UK's only occult talk show
    Presented by Dirk Bruere and Marc Power on ResonanceFM 104.4
    http://www.resonancefm.com
     
  17. Just bonding a copper sheet to it and etching would seem pretty easy.
    Vias are another matter.

    --
    Dirk

    http://www.onetribe.me.uk - The UK's only occult talk show
    Presented by Dirk Bruere and Marc Power on ResonanceFM 104.4
    http://www.resonancefm.com
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-