Pure copper apparently works in clean, dry environments. Lack of plating also
saves weight, which is critical in aerospace. The small company I was engineer
for had nothing but tin plated wire and terminals in its stock room. Some of
the wiring on cars is tin plated as well as all of the wires that came with my
Orion BMSs. It is harder to find in larger sizes, but Waytek wire stocks it.
I would use nothing but tin plated wires and connections in my EV and battery
projects. If unplated wire is used, the crimp compression pressure is much
more critical to prevent oxidation from destroying the connection. The wire
strands must be free of oxide to start. The pressure must be great enough to
change the shape of all the strands so no oxygen can get in between them. Tin
plated strands will form a long lasting low resistance crimp even with lower
crimp pressure. It also solders much more easily. Be sure that the solder
doesn't wick under the insulation or the wire will bend where the solder stops
and break there. This is why crimps are much more reliable than solder when
vibration is present. I had this happen several times where I tried to solder
repairs in the wiring of my 1942 army truck.
Phil Dooley
On Friday, February 27, 2026 at 09:53:33 PM EST, Lee Hart via EV
<[email protected]> wrote:
paul dove via EV wrote:
> 4.2.2.11 Tin
> Tin and tin plating shall not be used in any applications unless the tin is
> alloyed with at least
> five percent lead to prevent tin whisker growth. The presence of at least
> five percent lead shall
> be verified by lot sampling.
> The problem arises from variations and errors in the plating process,
> producing parts that have pure tin plating, despite certification that said
> they were not pure tin. Even if insulated and conformal coated sometimes
> whiskers would puncture to coating or insulation.
Ah, but lead has basically been banned from new products. Everything now
has to be RoHS compliant, which means no lead.
<https://en.wikipedia.org/wiki/RoHS>.
Pure tin is not that big a deal for things like terminals and
connectors, but is a problem for printed circuit boards and soldering.
The lead ban has forced an entirely new suite of alloys, fluxes, and
soldering protocols.
RoHS is "the law" in the EU. In the US, it's not federal law, but
several states have adopted Europe's RoHS requirements (California, New
York, New Jersey, Illinois, etc.) So in effect, even products sold in
the US need to meet the RoHS standards, unless you don't sell in those
states.
--
A nation of sheep will beget a government of wolves.
-- Edward R Murrow
--
Lee Hart, 2521 19th St N, St. Cloud MN 56303, www.sunrise-ev.com
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