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My first photo etch

Discussion in 'Electronic Basics' started by JazzMan, Mar 21, 2005.

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  1. JazzMan

    JazzMan Guest

    I've used various processes in the past to make boards including
    hand-drawn resist, laser transfer paper, and an odd technique of
    printing the reverse image on a peeled backing sheet of labels
    and ironing the toner onto the board. Results were ok, but I
    wanted to try the photographic process. Being too cheap to buy
    the light source I dug out my 25 year old fluorescent desk
    lamp with two 18" tubes. I didn't know how long to expose the
    board so I drew up a test image with the intention of using
    a light shield to vary the exposure along the length of the
    strip. Here's the result:

    The leftmost part was exposed for 5 minutes, going to
    the right in decreasing 30 second increments. Here's a closeup:

    The numbers are upside down, BTW.

    The narrowest horizontal lines are 0.025" and the narrowest gap is
    0.0045". This was soooo easy! I don't think I'll go back to the
    old ways except for quick and dirty projects. The only downside
    is the cost of presensitized boards, they're fairly expensive.

    Anyway, just wanted to throw this out there.

    Please reply to jsavage"at"
    Curse those darned bulk e-mailers!
    "Rats and roaches live by competition under the laws of
    supply and demand. It is the privilege of human beings to
    live under the laws of justice and mercy." - Wendell Berry
  2. Active8

    Active8 Guest

    On Sun, 20 Mar 2005 23:19:53 -0600, JazzMan wrote:

    You might look at think and tinker's dry-film. You can probably get
    a wal-mart laminator to apply it, but I've only checked the temp on
    my unit, so the jury's still out as to what modifications I'd need. ??
  3. Rex

    Rex Guest

    I think the hard part is finding a cheap laminator that will accept the
    thickness of a PCB. I tried this a few years ago and never got
    dependable laminations of the dry film with the cheap laminator I tried
    to use.
  4. Active8

    Active8 Guest

    What was the symptom? Did it mash your dryfilm? I ran a toner
    transfer through it a couple of times and it worked. I think slowing
    it down would allow me to do it in a single run. IIRC the laminators
    sold for dry film apply pressure but don't remember how much.
  5. Rex

    Rex Guest

    At the time I think the cheapest ThinkTink laminator was over $300. I
    bought a much cheaper one from a local office supply but it was not
    designed to accept .031 thickness. I opened up the case and made some
    mechanical mods to let it open up a bit wider. There were some screws to
    adjust tension which I also made externally accessable.

    As I recall, with mine, the laminate had kind of a wavy quality.
    Probably uneven heat or pressure. The one I had did not have heated
    rollers either -- it had a heating strip.

    Bottom line... you get what you pay for and I tried to go cheap. Hard to
    tell the mechanics of a laminator without opening it up and I think it
    matters a lot for this application.
  6. Clint Sharp

    Clint Sharp Guest

    How 'bout the fuser assembly from an old laser printer? Should be
    possible to buy a refurb assembly for an old Laserjet II,III or IV for
    little money. The temperature would need controlling and you'd have to
    drive it but............
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