What is the purspose of pre-tinned wire?

Mr. Haney wrote:


Tarnish is silver sulphide. It is no oxide. The tarnishing process is as follows..
8Ag + 4HS(-) <---> 4Ag2S + 2H2 + 4e-
Oxygen in the form of a water film is required - silver will not tarnish in dry air. This reaction mops up the electrons lost in the oxidation process
O2 + 2H2O + 4e- <---> 4OH(-)
Although the reaction is a classical redox process the end product is not an oxide - it is assuredly silver sulphide.
Since I'm sure there will be a deal of shouting from people about how this is bollocks, I would point out I have a degree and masters in the field and spent a lot of time researching silver adsorption reactions for silver oxide cells and lead acids - I do know what the deal is here.
As fo silver oxide being conductive - the biggest problem in a silver cell is the extra graphite needed to make it conduct - silver oxide is a p-type semiconductor. Silver sulphide is mode conductive than copper oxide though by a long way and is usedful because then the silver coat tarnishes it does not reduce the skin effect like the dielectric coating of copper oxide will.

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Chris Street wrote:

I own a couple of antenna that are silver plated for that reason !

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On Sat, 18 Apr 2009 22:04:11 +0100, Chris Street

No. You are correct.
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You don't understand what "oxidation" means.
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William Sommerwerck wrote:

I most assuredly do as I pointed out in the post above. The suplhide is an oxidation product but it is most assuredly not an oxide as has been claimed several times.
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William Sommerwerck wrote:

All he understands is trolling for attention
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On Sat, 18 Apr 2009 17:10:29 -0700, "William Sommerwerck"

Hmmm then Rust is actually Iron Sulfide?
I thought a high concentration of Sulfur had to be present for sulfidation to occur.?????????????????????????????????
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It could have been solid Silver.
Also, Silver plated wire DOES have favorable skin effect, sanded or not. Tarnished Silver wire would not be as favorable.
Can you say get a grip on what skin effect is?
The coil will do the job it is designed for in either case.
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Him abrading the less than 1/10th of one mil tarnish off with an abrasive does NOT reduce the size of the wire by ANY amount that would be measurable in the setting it was being used in.

At most "hand made radio" frequencies... yes. And the term is efficiency. It comes from the word efficient. There is no word "efficiant".
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I polished the roller coaster ATU in my 62 set with Brasso many years ago, but i think that was solid silver wire? My concern was to get a low resistance contact with the pick up wheel, rather than any surface effect.
Steve Terry
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wrote:

Silver oxide is acceptable. It remains as a mechanical part of the surface, and does not adversely affect conductivity.
Copper oxide is an unacceptable CRUST on your wire.
That is one reason why Sivler was used to plate copper wires.
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"Mr. Haney the Dickwad "

** But non existent on wires etc.

** Since it does not exist on wire surfaces, that is true.
Hanley is a TOTAL MORON !!!
...... Phil
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In article

My guess is that tinned wire is soldered more easily even after much exposure to unfriendly environments. You do not have any copper oxide to remove. Any crap in the tin flots away and new solder flows in under such crap.
Bill
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On 17 Apr 16:22, Salmon Egg wrote:

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?
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This thread has gone on along time without seeming to go anywhere. In a hope to end it and move on, I did a Google search. My best immediate hit was: http://www.cardinalproaudio.com/main/instrume.htm ,
It gave my reason first--it is easier to solder. The second one was also commonly posted. The tin protects against copper getting oxidized if it sits on the shelf for a long time.
What this site did not say was that the coating is not actually tin. But I as well as many other posters use the term tin instead of solder.
Can we move on now?
Bill
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wrote:

Tinning, in soldering nomenclature refers to dipping the stripped ends of a stranded wire into a solder pot after applying flux to it. "Pre-tinned wire" is a stranded wire where the entire length of the wire has been "tinned" (read solder impregnated) during manufacture, before the sheath (insulation) is added.
It is entirely different than TPC, which IS TIN plated copper wire.
Pre-tinned wire is made for manufacturing processes where labor costs have been pared down. It has nothing to do with shelf life other than how it relates to manufacturers and THEIR shelf life during a production cycle. It would oxidize at the same rate that a solder joint does, which is near NONE.
I doubt seriously that you will ever find RoHS "pre-tinned wire" anywhere as it is likely a very poor wire being tinned with RoHS solders.
PVC wire is more porous than tfe is, so it will allow oxygen to attack the wire, even though it is sheathed. TFE allows NO oxygen into the wire via the sheath, so it has a long shelf life regardless of the wire type inside.
So, TPC and SPC are true plated wire assemblies, and "pre-tinned wire" is a cheap way for a manufacturer to cut costs and give a cheaper product as well.
Pre-tinned wire is MORE susceptible to fracture due to flexing of the wire as it is actually a single strand as a result of the way it is made. TPC and SPC are true stranded designs and allow flexure without work hardening the copper inside.
Essentially pre-tinned wire sucks and is a lame choice for ANYONE trying to build a nice piece of equipment. The difference in cost is not enough to say that economizing by using it yields any benefit other than to expose the designer as a cheap, stupid bastard, at best.
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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).
The old-standard tin/lead tinning material can't be used in this high-temperature environment, as it would be melted by the heat of the Teflon extrusion, and would fuse a stranded-conductor wire into an inflexible single strand.
Not tinning or plating the wire would leave the surface of the copper exposed to high temperatures during the extrusion... I suspect that it would oxidize (if there's any free oxygen in that environment... dunno about that) or might react with the polymer. Even if it didn't react at that time, oxygen would infiltrate the wire at the cut end (albeit slowly) and the last few inches of the wire might end up with a significant amount of copper oxide on the conducter surface.
Silver-plating protects the copper from oxidation (I gather that silver oxide is somewhat easier for fluxes to deal with?) and the silver doesn't melt at the Teflon extrusion temperature.
I don't believe that the silver plating is thick enough to give the wire a significant conductivity advantage over pure copper, even at RF frequencies.
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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.
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(GregS) wrote:

This got to be audio grade !
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On Fri, 17 Apr 2009 18:59:48 GMT, snipped-for-privacy@zekfrivolous.com (GregS) wrote:

It is likely SPC and is Mil grade. There is no such thing as "audio grade". You have been talking to too many consumer electronics salespersons.
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