On Wed, 22 Apr 2009 18:39:16 -0700, Salmon Egg
wrote:

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


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 *******, at best.