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Tinning of electronic component leads

Discussion in 'Misc Electronics' started by Charles L, Apr 9, 2005.

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  1. Charles L

    Charles L Guest

    I heard somewhere that the leads of common electronic components (resistors,
    capacitors, transistors etc), such as you might buy from your local
    electronic hobbyist
    store, are tinned with a lead based alloy. Is this correct? Any help
    with this query would be appreciated.

    Charles L
     
  2. Al

    Al Guest

    Historically most components were either tinned or gold plated. The
    reason was for solderability.

    With the recent hysterical ban on lead, I have no idea what the new
    products are being "tinned" with. Have fun trying to solder to them.

    Al
     
  3. Guest

    Yes, you are correct.

    This is done to increase its solderability with conventional 60/40
    lead/tin (or is it tin/lead) solders used in the electronics industry.
    To the extent of my knowledge, having used it for over 60 years, it
    does not present any significant health hazard as carbon tetrachloride
    solvents once did.

    I've also used some silver based solders, but mostly on very high-end
    products like Tektronix Oscilloscopes which generally don't reach the
    consumer market.

    Sometimes you'll find gold plated leads on electronic components. This
    is to reduce the oxidation, while providing a very solderable surface.

    On copper plumbing, the use of lead based solders is now restricted,
    although many plumbers still use them because the new substitutes are
    very difficult to work with and produce a water tight joint. Again,
    I've never heard of a health problem the resulted from the use of lead
    based solder on copper plumbing. What you want to avoid is PVC water
    supply plumbing, which has caused documented health problems.


    Harry C.
     
  4. spudnuty

    spudnuty Guest

    The classic case of lead in water was the grandfather who exhibited
    signs of lead poisoning when no one else in the family did. Turns out
    he always drank a lot of water in the morning after it had been
    standing in the pipes overnight.
    Lead is also a documented cause of birth defects. All the items I buy
    from that surplus place in California carry a warning.
    In the '50s we used to play with asbestos mineral and mercury. Kids
    would bring mercury to school and we'd coat coins with it. Do that now
    and they'd have to shut the school down and decontaminate.
    Richard
     
  5. Al

    Al Guest

    And as a result of your experiments with mercury, are you a blithering
    idiot? I don't think so!

    Do you know what a "mad hatter" is? (Aside from "Alice in Wonderland.")
    At one time, mercury salts were used to in the manufacture of hats. The
    people who made the hats were exposed on a daily basis to copious
    amounts of mercury. As a result, they got mercury poisoning.

    Now, water is not considered toxic, is it? But if you are exposed to
    copious amounts of water, where it doesn't belong, like your lungs, you
    will experience symptoms also.

    Moderation in all things is my motto.

    Al
     
  6. Guest

    Spud, the real question may be what he mixed with that water before
    drinking it! (Just kidding.)

    Realise that there are many things that display the same symptoms as
    lead poisoning. I'd seriously be curious what an autopsy revealed and
    if so did it disclose any unusual levels of lead in his body, and what
    his cause of death was.

    The solubility of oxide coated lead in water is normally so low that it
    cannot produce a health risk. Remember that the Romans used it for the
    linings of their aquidiucts, some of which are still in use without
    negative health effect of any note, after over 1,000 years. My home is
    plumbed with copper pipes that are joined by traditional 60/40 tin/lead
    based solder, but the amount of exposure of the lead on the joint is so
    minimal that it cannot be detected on water analysis (which I actually
    had performed). Lots of copper in the water though, so maybe it's time
    for society to return to galvanized pipe in the home if someone is
    overly concerned.

    What concerns me most from a health standpoint is that the water supply
    from the street main to my home is some sort of a black plastic pipe,
    which may be PVC or HDPE. This supply line is over 100-foot long from
    the street, and it poses some concern for me since PVC is now resricted
    from use in water supply line plumbing.

    On a more positive note, I'm now 67 and have lived in this house for
    the past 30 years, and suffered no ill effects. My children are now in
    their 30s and 40s, also having displayed no ill effects. I've also
    ingested small amounts of led fumes throughout the past 50+ years from
    soldering and working with solder pots, still without ever having any
    ill effects.

    I have no doubt that the toxic effects of lead poisoning are now well
    documentated, but most of the case studies reveal these cases to be
    based upon small children that for some reason ingested lead based
    paints containing enormous amounts of lead by by chewing on products
    containing them, or by workers in industry who absorbed toxic level of
    lead fumes in the course of their daily work.

    In closing, years back I owned a printed circuit board manufacturing
    facility in which the resist employed was a tin/lead solder plate. For
    gold plating the contact finger of the circuit boards, a chemical etch
    was employed to remove the solder coating before a cyanide based gold
    plating was applied. Curously, anyone that worked with this process was
    required to have a state lawy imposted blood test for lead, but not for
    the far more deadly cyanide. Still, no one including myself ever failed
    that blood test for lead. No one was tested for cyanide, which I assume
    if it doesn't kill you, is relatively harmless.

    Just for the record, the real health hazard in the printed circuit
    business is not the lead, or cyanide, but organic solvents that we use
    in the process. Things like trichlorethylene, methyl and ethyl acetate,
    acetone, MEK, etc. None of these are federally regulated. Many of these
    are capable of making you feel a bit high or dizzy, then fall into an
    uncouscious state, with death immediately followiing.

    Go figure. To me it's obvious that neither the regulators or the media
    have any hint of a clue.

    Harry C.
     
  7. Guest

    Spud, the real question may be what he mixed with that water before
    drinking it! (Just kidding.)

    Realise that there are many things that display the same symptoms as
    lead poisoning. I'd seriously be curious what an autopsy revealed and
    if so did it disclose any unusual levels of lead in his body, and what
    his cause of death was.

    The solubility of oxide coated lead in water is normally so low that it
    cannot produce a health risk. Remember that the Romans used it for the
    linings of their aquidiucts, some of which are still in use without
    negative health effect of any note, after over 1,000 years. My home is
    plumbed with copper pipes that are joined by traditional 60/40 tin/lead
    based solder, but the amount of exposure of the lead on the joint is so
    minimal that it cannot be detected on water analysis (which I actually
    had performed). Lots of copper in the water though, so maybe it's time
    for society to return to galvanized pipe in the home if someone is
    overly concerned.

    What concerns me most from a health standpoint is that the water supply
    from the street main to my home is some sort of a black plastic pipe,
    which may be PVC or HDPE. This supply line is over 100-foot long from
    the street, and it poses some concern for me since PVC is now resricted
    from use in water supply line plumbing.

    On a more positive note, I'm now 67 and have lived in this house for
    the past 30 years, and suffered no ill effects. My children are now in
    their 30s and 40s, also having displayed no ill effects. I've also
    ingested small amounts of led fumes throughout the past 50+ years from
    soldering and working with solder pots, still without ever having any
    ill effects.

    I have no doubt that the toxic effects of lead poisoning are now well
    documentated, but most of the case studies reveal these cases to be
    based upon small children that for some reason ingested lead based
    paints containing enormous amounts of lead by by chewing on products
    containing them, or by workers in industry who absorbed toxic level of
    lead fumes in the course of their daily work.

    In closing, years back I owned a printed circuit board manufacturing
    facility in which the resist employed was a tin/lead solder plate. For
    gold plating the contact finger of the circuit boards, a chemical etch
    was employed to remove the solder coating before a cyanide based gold
    plating was applied. Curously, anyone that worked with this process was
    required to have a state lawy imposted blood test for lead, but not for
    the far more deadly cyanide. Still, no one including myself ever failed
    that blood test for lead. No one was tested for cyanide, which I assume
    if it doesn't kill you, is relatively harmless.

    Just for the record, the real health hazard in the printed circuit
    business is not the lead, or cyanide, but organic solvents that we use
    in the process. Things like trichlorethylene, methyl and ethyl acetate,
    acetone, MEK, etc. None of these are federally regulated. Many of these
    are capable of making you feel a bit high or dizzy, then fall into an
    uncouscious state, with death immediately followiing.

    Go figure. To me it's obvious that neither the regulators or the media
    have any hint of a clue.

    Harry C.
     
  8. Guest

    I believe it's 60% lead and 40% tin.
     
  9. Guillaume

    Guillaume Guest

    Lead is not used much anymore for environmental reasons.
    A common alloy used for tinning component leads nowadays contains Sn
    and Ni.
     
  10. In my teens (35 years ago or so) I saw a friend actually pour the
    stuff on a cloth and put it up to his nose and sniff it. He survived!
    I think what saved him was that he lost consciousness so quickly that
    he didn't breath much in. Remember the aftermath of the death blow to
    Apollo Creed in Rocky IV? My friend went the same way, eyes rolled
    back, fell forward on his face (went face-first into a deep freeze)
    and didn't even attempt to stop himself; he was out like a light.
    Scary.

    Tom
     
  11. Guest

    Read up on the history of carbon tetrachloride, because the toxicity
    issue was a puzzle for many years. For years it was used as an
    industrial solvent, a standard solvent in every radio and TV repair
    shop, and even sold as a safe, non-flamable household cleaning agent
    under the name Carbona Cleaning Fluid.

    Most users experience no adverse effects, still other died. For years,
    no one could figure out what the difference was.

    Some bright guy in the 1950s finally solved the mystery and found out
    what was happening. It turns out that if you had even a small level of
    alcohol in your bloodstream, the combination with carbon tet was lethal
    and had no medical cure. I don't recall if if was your liver or kidneys
    that the combination destroyed. Perhaps someone else here does.

    At any rate, rather than banning alcohol, the government banned the
    general sale and use of carbon tetrachloride.

    This made big news in the electronics magazines of the 1950s. Later,
    trichlorethlene was introduced as a safe replacement for carbon tet but
    it turned out to be carcinogenic. Later a number of freon solvents were
    introduced, but not only were they lousy solvents, they were later
    discovered to pose an environmental risk and banned.

    Likely the only general purpose grease and oil solvent available on the
    market today is unleaded gasoline, which sort of takes us full circle
    back to the starting line! :)


    Harry C.
     
  12. spudnuty

    spudnuty Guest

    Al wrote
    Yes I do remember that cleaning fluid, as well as the glass globes that
    were used as fire extinguishers "toss at the base of flames" Some even
    had a heat sensitive trigger that would release the carbon tet in a
    fire.
    Al, I was always leery of messing around with that mercury so as a
    result my exposure was limited. Now I just read in Discover magazine
    that they discovered a genetic marker for sensitivity to mercury. I
    think that exists with other chemicals too. I worked in the photo
    industry for many years and always tried to use tongs and rubber gloves
    in working with methol the developing agent. I met a few old timers who
    had developed an acute reaction to it. They couldn't be in a building
    where it was being used without developing a severe reaction.

    I grew up on a farm in the west and in the '50s we were using two weed
    killers. 2-4-D and 2-4-5-T. The first was a broad leaf killer and the
    2nd killed everything. I never liked either of them but was
    particularly afraid of 2-4-5-T. I took a lot of ribbing over my mask,
    rubber everything goggles etc. but I figured anything that anything
    that could knock down my mom's roses 50 yards down wind, 5 mph wasn't
    nice. It was bright orange. Guess what that was called when I saw it on
    TV in Viet Nam?
    Now they actually use a chemical to keep the canals and ditches clear
    of moss. It's so dangerous that the last time I was out there a county
    guy accidentally sprayed it all over himself. He died. I suppose that's
    why there are no frogs or toads in those irrigation ditches anymore.

    Sometimes the hazards are obvious sometimes we're just ignorant. I saw
    kids at the Buster Brown Shoe store stick everything they could into
    that fluoroscope they used to check where your toes were in the shoes.
    http://www.orau.org/ptp/collection/shoefittingfluor/shoe.htm
    I was also very careful about sound levels on the farm, now my dads
    nearly deaf and my brother's on the way.
    ..
    Harry, they took lead out of the gas. Remember the gray residue that
    used to build up on your sills if you lived close to a street with a
    lot of traffic on it especially at a stop light? Does anyone remember
    the old tooth paste tubes? They always felt suspiciously heavy to me.
    Ha just Googled it:
    http://www.saveyoursmile.com/toothpaste/toothpaste-a.html
    and I do remember them changing the water supply lines to houses. In a
    lot of these old houses I still see lead pipe supplies coming from the
    street.
    Richard
     
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