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lead free solder

Discussion in 'Electronic Repair' started by [email protected], Aug 30, 2006.

  1. Guest

    I was planning on getting into electronics as a hobby seriously, and I
    read that they have or will ban lead solder. Is it already illegal? Is
    traditional lead/tin/rosin solder still available to buy? Do we really
    need such a ban? I think I should stock up on the traditional solder if
    I can because from what I read, lead free solder is terrible,
    especially since I want to mainly work on repairing old electronic
    equipment. I'm wondering if it will even be possible to be an
    electronics hobbyist anymore.
     
  2. Arfa Daily

    Arfa Daily Guest

    The situation is complex, and it depends on where exactly you are located.
    As far as Europe goes, leaded solder is NOT illegal, and is unlikely to
    become so. Supplies are still fairly readily available, although not as
    abundantly as they were, as obviously, there is less demand. The directives
    regarding the use of lead-free solder, allow for amateur and non-commercial
    use of leaded solder, basically without restriction. Any equipment which was
    "placed on the market" prior to July 1 2006, can be repaired, commercially,
    using leaded solder if you wish. If it was constructed originally using
    leaded solder, then the general opinion is that it should be repaired using
    leaded solder, as there is considerable controversy as to whether leaded and
    lead-free solder alloys mix to produce a joint with long-term stability.

    If the item was originally constructed using lead-free, then for the same
    reason, use lead-free to repair it. Any item that was placed on the market
    after July 1 2006, will definitely be constructed using lead-free solder,
    and lead-free components ( the other angle to staying within the terms of
    the directive ). If you are a commercial repairer, you MUST use lead-free
    solder and direct replacement or compatible lead-free RoHS ( Restriction of
    Hazardous Substances ) certified components to perform any repair on this
    equipment, and not commit a theoretical criminal offence. I say theoretical
    because to date, I am not aware of anyone being prosecuted, or any means
    being in place to police the directive.

    You are not required to follow the terms of the directive for this
    equipment, if you are working on it non-commercially ie for your own
    personal purposes. Most commercial equipment has been manufactured in
    lead-free for more than 2 years now, and some manufacturers - Sony for
    instance - have been insisting for some time that their dealers use only
    lead-free solder for carrying out repairs to their equipment, irrespective
    of age or original construction materials, so apparently, they don't believe
    that there is an issue with mixing alloys.

    There is a lot of information on the web about this if you search " RoHS "
    directive. Also, there is a lot of valuable information on the major
    component suppliers' websites such as Farnell and RS Components. If you can
    get hold of a copy of " Technology @ Home " magazine ( last issue ) -
    www.technology-at-home.co.uk you can find the more comprehensive article
    that I did.

    Arfa
     
  3. Eeyore

    Eeyore Guest

    You *need* tin lead solder for repairing old gear and it's still widely
    available for that very reason. It's also hugely nicer to use.

    There are a number of categories of equipment that are still allowed to use tin
    lead solder too. The lead free thing is intended mainly I think to apply in
    reality to consumer goods but the legislation in the EU doesn't distinguish as
    such.

    Graham
     
  4. Mixing leaded and lead-free solders can be problematic. Generally if a
    device was built using leaded solder then leaded solder should be used
    for repair. For lead free assemblies, of course lead free solder should
    be used. The big question is, how will you be able to tell whether or
    not a board was put together using leaded or lead-free solder?
    Hopefully some mfrs will mark their boards accordingly but I doubt if
    many will. Just because some components may be marked as being 'lead
    free' or 'RoHS compliant' doesn't mean the board was assembled with lead
    free solder. Lead free parts will work fine with leaded solders as well
    as lead free solders.

    As far as hobby work goes there's nothing wrong with using lead free
    solder for hand work. It's slightly more difficult to work with, but
    high silver bearing solders such as SAC305 formulas seem to work the
    best. Using lots of flux is important as well, since a more agressive
    flux is needed than with tin/lead solder to ensure proper wetting. But
    if you are a soldering newbie it might be better to start out with some
    tin/lead solder until you get the hang of it as it is a little more
    forgiving...

    -Jeff
     
  5. Are there manufacturers that are not marking their boards for lead content?
    I thought it was required in Europe and all of the CE vendors that I have
    seen in the US are marking the boards.

    What is the problem with mixing the solders? Other than the lead free types
    making it harder to rework and needing slightly higher temps, what problems
    are there? What does "problematic" mean in this case? Is there a real
    issue or does it mean that you are not sure and are being conservative?

    Leonard
     
  6. Arfa Daily

    Arfa Daily Guest

    Hi Leonard

    I have done quite a bit of research into this, and have corresponded with
    several experts in the field, and it seems that the jury is still out on
    this one. Half of the solder manufacturers say that it's ok to mix leaded
    and unleaded, and half say not. Some of the experts that I have spoken to
    say definitely not, so make up your own mind. I prefer not to mix them, as
    it seems that marginally more people seem to be saying don't than do. As the
    solder is still available, I see no reason to risk an unknown long term
    compromise in the stability of the joint, and will continue to use like for
    like, unless forced by product availability, or legislation, to do
    otherwise.

    Personally, I think that the whole thing is an ill-conceived and poorly
    thought through excuse to justify the existence of an EU department, and the
    jobs of those who work in it. And, as I've said before, the avionics
    industry, and medical instruments industry, amongst others, have been
    granted an exemption, and the American military flatly refuse to use it, so
    what are we to make of that ... ?

    Arfa
     
  7. From what I've read about the subject, it comes down to metallurgical
    issues. If a part with tin/lead plated leads is used in a lead free
    process, the lead will contaminate the joint. As little as 0.5% lead is
    enough to weaken the joint and lead to cracking around the footprint.
    What happens is the lead, as it melts at a lower temperature than tin
    (we're not talking about alloys here but trace contaminating amounts),
    will collect in the joint at the place that cools last, which is the
    center of mass, right under the footprint. (Obviously we're talking
    about SMT components here). This reduces the amount of tin doing the
    actual bonding of the lead and can lead to early joint failure.

    Boards made with lead free solders have been found to have better
    reliability when thermally cycled, one reason the automotive companies
    have embraced lead free assembly here in the USA. Long term reliability
    due to tin whiskers is the issue no one wants to talk about however, as
    the process of whisker formation is still not well understood.

    -Jeff
     

  8. Tin can fracture at low temperatures.


    --
    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
     

  9. Lenoard, From what I've read you should wick away most of the old
    solder and do the repair with eutectic solder


    --
    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
     
  10. I usually do, adding some fresh solder to help it off.

    Leonard
     
  11. Eeyore

    Eeyore Guest

    Yes, but I gather that the other way round is just fine.

    Graham
     

  12. Do you leave a tiny bit of saturated braid on the end when you trim
    it? It helps conduct the heat to the joint faster and minimizes heat
    damage. I try to leave about half the width of the tip when I trim
    solder wick, then dip it about 1/4 inch into fresh liquid RMA flux. I've
    changed thousands of ICs this way with almost no damage to the PC
    boards.

    The few that were damaged were mostly due to other causes, like some
    idiot slamming a fist down on the bench while you're working because
    they think you're ignoring them, or defective PC boards that have all
    kinds of loose foils and pads. I have to see if my digital camera will
    do decent macro shots. If it does, I'll put some pictures for the new
    people on my website. BTW, How's business?


    --
    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
     
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