On Fri, 17 Apr 2009 15:20:00 +0100, Ian Bell
wrote:

Sandi wrote:
On 17 Apr 04:49, Ross Herbert wrote:

On Fri, 17 Apr 2009 04:14:40 +0100, Sandi
wrote:

: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
nly minimal cleaning.
:
:Sounds like a good thing to me, so why isn't almost all wire
re- tinned?
:
:Is cost really so different?
:
oes 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.

Is it real "tin" that's used?


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

Cheers

ian


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.