Plating Question

"Few things bring out OCD like connectors.  What seems to be so simple often is not. For example, did you know that tin joined to copper is a bad idea.  The metals can react and form dreaded dendrites. Yikes!"

After your edit -

"CORRECTION--it is tin and gold (not copper) that will react causing fretting and dendrites.  These are forms of corrosion that impair electrical conductivity."

@corelli I think you're full of crap and should look up the definition of dendrite!

From Miriam Webster's Dictionary -

"dendrite
noun
den·​drite ˈden-ˌdrīt 

1: a branching treelike figure produced on or in a mineral by a foreign mineral
also : the mineral so marked

2: a crystallized arborescent form

3: any of the usually branching protoplasmic processes that conduct impulses toward the body of a neuron"

In case you're wondering from YouTube:

2: a crystallized arborescent form -

"The arborescent form of crystals is characterized by tree-like structures that grow from a central point, resembling branches. This form is commonly observed in minerals such as copper, gold, and silver, where the crystals interlock and grow in a manner that resembles a tree. The process of crystallization in this habit is influenced by various factors, including the mineral's chemical composition and the environmental conditions during its formation."

How in any way is this harmful or detrimental continuity? Tin and Gold have been combined and been in widespread use for I don't know how long and is commonly seen on PCB edge connectors and countless other applications throughout the electronics industry. Particularly where continuity of an electrical connection is critical over very long periods of time. In any electronic product really.

I have made many cables from old stock Western Electric copper wire that was tin-plated to resist corrosion.  I like soldering connections used with tinned copper wire (vs. a crimped connection), presuming the soldering process should melt the tin plating for an improved connection with the copper base metal.

I have used both unplated and plated (usually gold) pure copper connectors, but it seems perhaps excessive to obsess over plating when it is far more common to find connectors (wire and chassis connectors) made from a plated copper alloy with much lower conductivity than pure copper, such as Tellurium copper (50%), brass (25-50%), and Phosphor bronze (10-20%).

Have any of you seen studies/measurements of conductivity comparing bare copper with plated copper?  Is there really a penalty for the plating? I am skeptical that the difference between unplated and plated connectors could be heard by direct comparison.  Below is an excerpt/conclusion from AI (link to the whole response).

"For practical electrical connector applications, the initial, theoretical conductivity advantage of pure, unoxidized copper is often outweighed by the long-term stability and reliability offered by plated copper."

@ faustuss

thanks so much for your civil response.  Please do a bit more of "research" and you will see that no reputable metallurgical engineer would ever suggest mating tin and  gold.  Here is one of many comments of the subject:

https://www.greatplainselectronics.com/Information.asp?region=140#:~:text=It%20can%20take%20months%20or,the%20same%20contact%20plating%20type.

And no metallurgical engineer would tell you cryo treatment makes a difference in how electricity travels along wiring, yet lots of non-metallurgical engineers tell you they can hear a difference. 

@corelli  I’ve always used silver plated copper

• Pure copper can oxidize and turn green, which impedes signal transfer and can cause pitting on the surface of the connector
• Whereas silver plated copper combines the two best conductors and the silver plating only tarnishes. Tarnish has to be very severe to impede signal transfer to the same level as oxidized copper
• The tarnish can often be removed simply by reseating the connector, restoring the original conductivity
• Other plating materials do not have the conductive properties of silver or copper
• But if you want "pretty cables" then gold or rhodium look really good🥴

But ithe design of the connector also plays a key role in connector performance.

• Some of the best connectors currently available come from KLE Innovations

Silver plated copper will provide...

• Fastest dynamics
• Best imaging
• Finest micro details
• Articulate signal transfer

But that’s just my opinion after designing and building DIY HELIX cables, with the help of many others from around the world, for over 12 years.

Hope that helps