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What is the purspose of pre-tinned wire?

Discussion in 'Electrical Engineering' started by Sandi, Apr 17, 2009.

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  1. Sandi

    Sandi Guest

    Some insulated multistrnd copper wire is pre-tinned and a lot is
    not.

    What is the purpose of pre-tinned wire? As far as I can see the
    advantage is that the copper core doesn't oxidise which means the
    wire can be soldered or fixed to a terminate with only minimal
    cleaning.

    Sounds like a good thing to me, so why isn't almost all wire pre-
    tinned?

    Is cost really so different?

    Does the tinning-coating replace where copper would have been in
    the overall wire and tinning is of higher reistence?

    Is flexibility affected?
     
  2. Ross Herbert

    Ross Herbert Guest

    :Some insulated multistrnd copper wire is pre-tinned and a lot is
    :not.
    :
    :What is the purpose of pre-tinned wire? As far as I can see the
    :advantage is that the copper core doesn't oxidise which means the
    :wire can be soldered or fixed to a terminate with only minimal
    :cleaning.
    :
    :Sounds like a good thing to me, so why isn't almost all wire pre-
    :tinned?
    :
    :Is cost really so different?
    :
    :Does the tinning-coating replace where copper would have been in
    :the overall wire and tinning is of higher reistence?
    :
    :Is flexibility affected?


    As you surmised, the answer is cost. It is not the cost of the tin itself but
    the additional process and handling which adds to the complexity of production.
    The copper conductor wire gauge is not made smaller where tinning is not applied
    and the added few microns of tin would not affect resistance/unit length by any
    significant degree. Flexibility is not an issue.

    I think that manufacturers realise the majority of termination methods used
    today rely on crimping or soldering while the copper conductors are clean.
    Tinned conductors are an advantage where the conductors are secured by screws or
    wire-wrap although less so for the latter. Insulation displacement techniques
    are not a problem for untinned conductors.
     
  3. Steve Terry

    Steve Terry Guest

    Tin has a much lower conductivity than copper, and as RF travels on
    the surface of a conductor, it would attenuate RF and high frequency AC

    Steve Terry
     
  4. Phil Allison

    Phil Allison Guest

    "Pilgrim"

    ** No.

    Teflon coated wire intended is for high temp applications.

    Silver has a much higher melting point than tin ( just a tad below copper)
    and is more corrosion resistant too.



    ...... Phil
     
  5. GregS

    GregS Guest

    Most of my TFE coated wire is not silvered butl is tinned. All TFE wirewrap is
    silvered.

    greg
     
  6. Steve Terry

    Steve Terry Guest

    Yes, Silver is one of the few metals that has a lower resistance than
    copper,
    but oxidises easily so silver should be covered, PTFE is one of the best
    coverings.

    Steve Terry
     
  7. Ian Bell

    Ian Bell Guest


    No, it is usually tin/lead alloy, better known as solder.

    Cheers

    ian
     
  8. Some of the newer wires have PTFE-Polyimide-PTFE insulation. Best of
    both worlds.
     
  9. Not any more (post-RoHS). (Solder, yes, but not lead.)
     
  10. GregS

    GregS Guest

    My understanding is that the Teflon-insulated wire uses silverplating
    for a couple of reasons, related to the high melting point of Teflon
    (and thus the high temperatures to which the wire is exposed when the
    Teflon is melt-extruded onto the conductors).[/QUOTE]

    I checked looked at a spool of about #20 stranded wire. It does look very shiny like silver.
    I thought it was odd looking at it. its made up of a tightly twisted center
    section and a loosly woven outer section around the inner section. The TFE is
    almost a fluorescent blue. Neat stuff. 19/32 strands.
     
  11. GregS

    GregS Guest


    This got to be audio grade !
     
  12. Ian Bell

    Ian Bell Guest


    Fortunately I stocked up on the real stuff before they banned it ;-)

    Cheers

    Ian
     
  13. Steve Terry

    Steve Terry Guest

    Beats me?

    Steve Terry
     
  14. Sandi

    Sandi Guest

    That's what I would have thought too. But if pre-tinned (plastic
    insulated) wire is so useful in this respect then why isn't pre-
    tinned found more often?

    I'm not thinking of the use of wire at RF frequencies but as an
    interconecting wire.

    I haven't managed to compare the cost of pre-tinned wire identical
    plain copper wire but I don't ever recall seeing tinned wire and
    thinking it was unexpectedly expensive. Has anyone got any info
    from making this comparison in the past?
     

  15. In the telecom industry the rule is "silver on silver". Back in the
    bad old days there could be problems with diss-simmilar metals
    corroding & creating noise on circuits both from rectification effects
    & from current punch-through across the junction when voltage was
    applied to the circuit, i.e. "going off-hook". In some cases
    "sealing" current was (& still is) applied on a constant basis to
    circuits that didn't require it for operation, just to keep junction
    corrosion from getting bothersome.

    Although not part of the original Bellcore standard I've actually
    speced tinned wire for T1 circuits going into areas I knew were going
    going to be climate controlled.

    H.
     
  16. Silver does not oxidize so much as it tarnishes,
    Same thing. Chemically, it's oxidation. Silver cleaners/polishes are
    reducing agents (eg, Tarn-X).
     
  17. Mr. Haney

    Mr. Haney Guest


    Folks in this discussion need to define "pre-tinned".

    There is TPC wire, which is individual TIN plated Copper strands made
    into mutli-stranded wire in the same process as any other stranded wire.

    There is SPC, which is individual Silver plated Copper strands.

    It was always my understanding that "pre-tinned" wire was stranded wire
    that was run through a solder bath and tinned similarly as the 'tinning'
    one would give the end of a wire in a solder pot.

    If the wire is this type, it is used in certain industries to reduce
    production labor costs. It is specifically NOT used in certain other
    industries due to the problems associated with cinched type termination
    processes and an effect known as 'solder creep'.

    TPC is TIN plated, not solder plated. Just like it states.

    "Pre-tinned wire" IS processed using solder.
     
  18. Mr. Haney

    Mr. Haney Guest


    Sorry, but TPC wire was already RoHS compliant. All the idiots had to
    do is change the label. TIN is TIN. It doesn't say "SPC" (Solder PLated
    Wire)... It SAYS TPC TIN Plated Wire. Pretty simple.

    SPC (Silver, of course) is better anyway... particularly from a shelf
    life POV.

    I hate TPC wire that has been around too long. The crap won't even
    take solder. Give me SPC any day. The cost difference is negligible, if
    one weighs the added labor cost of dealing with poor quality TPC, which
    nearly all of it is.
     
  19. Mr. Haney

    Mr. Haney Guest

    That's why one should use SPC, which is Silver plated Copper.
     
  20. Mr. Haney

    Mr. Haney Guest


    Wrong. The customer gets what the customer buys. If all YOU were
    exposed to was SPC TFE, the THAT was ALL your employer was buying, you
    dope. TPC was just as prevalent, despite the fact that it sucks on so
    many levels.
     
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