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 only minimal
:cleaning.
:
:Sounds like a good thing to me, so why isn't almost all wire pre-
: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.