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Couple of noob questions

Discussion in 'Electronic Basics' started by [email protected], Dec 6, 2005.

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  1. Rich Grise

    Rich Grise Guest

    Good Grief! The only thing wrong with 2.95/quart FeCl3 is that you have
    to use good etching techniques and practices. You make the stuff sound
    like cyanide (which, BTW, is used routinely in industry). It's really
    quite innocuous. When it doesn't etch copper good enough any more,
    you can either recharge it with some acid, which probably _is_ fairly
    hazardous to handle, or dump a bunch of "washing soda", sodium carbonate,
    into it, and _then_ it's safe to pour down the drain, although I also
    hear it makes some kind of muddy sludge, which might or might not flush
    well.

    If _that_ makes you paranoid, then decant the supernatant liquid through
    a filter of some kind - a coffee filter would probably be fine, and just
    toss the sludge into the trash. It's basically rock powder, which either
    Spehro Pefhany or John Popelish has pointed out. Or maybe both. ;-)

    But, depending on your budget, and how much screwing around you want to
    do - it once took me all day to make one 6" x 9" board, not counting
    having the artwork shot. It might be simpler to send out some kind of
    artwork - I hear that there are electronic CAD programs that will output
    Gerber files, and there are board houses that can make you a board for,
    like $50.00. I'm confident someone will clarify that, if I'm misinformed
    about pricing. :)

    Good Luck!
    Rich
     
  2. Rich Grise

    Rich Grise Guest

    These arent related (taking a part vis-a-vis using chemicals).

    But they _do_ miss the parts. I know, I've been there, done that. But
    there's a trick. You find the guy who's responsible for the parts, and
    _ask_ him. "How can I check out parts for home projects?" They might
    just say, "help yourself", they might say, "We can sell them to you at
    our cost", they might say, "Welcome to the Future" - one doesn't know
    until one finds out, does one? ;-)

    Have Fun!
    Rich
     
  3. Rich Grise

    Rich Grise Guest

    For what it's worth, I recommend against boards with long strips.
    Admittedly, it's been a few years since I've used "perfboard" (that's
    what we call it in Leftpondia, or "vectorbord", yes, that's "bord",
    it's a trademark. But my favoritest of all is the kind with ground
    plane on one side, actually a grid, with clearance for each and every
    hole, and a pad-per-hole on the other side. I just don't trust my
    skills at chiseling away at a copper band on a prototyping board. And
    it's remarkably easy to wire it point-to-point with #30 wire-wrap wire,
    especially if you have a good stripper: I ground down the rivet and
    took the stripper blade off a WSU-30M once:
    http://www.mouser.com/catalog/624/1599.pdf
    and clamped it in an X-acto knife handle:
    http://www.reuels.com/reuels/page173.html
    so I could daisy-chain wire-wrap wire by just sliding the whole
    insulation down the wire, stripping about 3/16" for each connection.

    Good Luck!
    Rich
     
  4. Rich Grise

    Rich Grise Guest

    Not "adhere", but it will melt itself into plastic.

    What kind of plastic perfboard are you using? Frankly, it's the first time
    I've ever heard of any - they're either phenolic or fiberglass.
    Which metal surface is this?
    And, as I've said, see if you can find one with individual pads - you
    can solder the parts in place (to the pads), and _then_ string your
    wires.

    Good Luck!
    Rich
     
  5. Rich Grise

    Rich Grise Guest

    I've heard that there _is_ "solder" that will "stick" to aluminum, but
    I've also heard that it's such a PITA to try to get it to operate properly
    that it's worth it to just take your aluminum parts to a TIG shop. :)

    Have Fun!
    Rich
     
  6. k wallace

    k wallace Guest

    This post has some great soldering advice that I plan on studying in
    much more detail. My soldering consists of fairly simple hobby-type
    stuff, but still I'd like to be able to make those perfect little
    "hershey's kiss" type solder-dots. Now, I can solder small things
    together without shorting two things close together, but I've *never*
    figured out the technique to make those perfect-looking little pointy dots.
    Any specific advice for that? I generally use rosin-core 60/40 RS
    solder, btw. is that less-than-recommended for the level of 'perfection'
    i'm desiring, or is it all in the solderer's control? remember, i'm not
    a pro nor do i play one on tv- just an occasional hobbyist but I *am* a
    perfectionist, and ugly solder joints just bug me.
    TIA
    karinne
     
  7. Solder joints should have the Hershey Kiss look, only if there is a
    lead sticking up out of the joint, with the solder wetting up the wire
    and pad below it. A solder dot on a pad should be smooth a shiny on
    top, more like an M&M or a small donut. Anything rough or with points
    indicates either oxidation on the solder (iron too hot so it burns all
    the flux off or there was not enough flux to cover the solder and keep
    it from being exposed to oxygen before it solidified) or soldering
    iron too cold to melt the solder fully. A good alloy like 63% tin,
    37% lead or 62% tin, 36% lead, 2% silver also flows a bit better than
    60%tin, 40%lead, or (shudder) 50% tin, 50% lead, or (cringe) 40% tin,
    60% lead.

    Don't dab with the iron. This just helps oxygen get mixed with the
    molten metal, creating dross on it. Apply heat to the pad and wire to
    be joined, perhaps with a touch of solder between iron and metal, to
    form a thermally conductive path. Then sweep the end of the solder
    around the lead to spread the flux to wet everything that needs to be
    coated with solder. This sounds like a lot of solder, but if you are
    using something like .02 inch diameter, or .032 inch, it need not be
    very much.

    Finish by sliding the iron up the lead, so the excess follows the iron
    up. Then, when you trim the lead, you also trim the excess solder
    off. You should end up with a tiny Hershey's Kiss with the top
    trimmed off (ideally, with flush cutters for a flat, non snaggy tip).

    Never use acid core solder on electronics, because the flux residue is
    both corrosive and conductive.
     
  8. Rich Grise

    Rich Grise Guest

    Just in hopes of keeping you from going down the wrong track here,
    a "hershey's kiss" solder blob means you've used at least three times
    as much solder as you should have. It should be a smooth fillet,
    that just blends in to both the copper dot on the board (which should
    have already been tinned) and the component lead. For SMT, a fillet
    joint with minimal solder is almost de rigeur, IIUC. (I think they
    call that "sweat-soldering" - the solder wicks up between the pad
    and the chip by capillary action.) What you want is good wetting.
    Practice, practice, practice. :)

    Here ya go:
    http://images.google.com/images?q="good+solder+joint"&btnG=Search+Images

    Have Fun!
    Rich
     
  9. Rich Grise

    Rich Grise Guest

    NO! NO! NO!!!

    There should be no blob. It should make a smooth transition - at the
    edge of the solder fillet, it should just feather into whatever it's
    supposed to be bonding.

    If you have a lump like a Hershey Kiss, or an M&M, or a "small donut",
    you're doing everything exactly wrong - iron's too cold, too much
    solder, didn't heat up the component lead or the pad enough to get
    good wetting. Solder is _NOT_ hot-melt glue.

    I looked up "Good Solder Joints" (with the quotes) on Google images -
    http://images.google.com/images?q="good+solder+joint"&hl=en&btnG=Search+Images

    lemme go see if I can go pick a really good example...
    http://www.antex.co.uk/images/betterfig5.jpg

    Here's an example of a very bad solder joint:
    http://aplsweb.com/Wiper-Fix/Wiper10.jpg

    This is a very long link - please do mind the wrap:
    http://images.google.com/imgres?img...nt%22&svnum=50&hl=en&lr=lang_en&safe=off&sa=G

    Have Fun!
    Rich
     
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