Tinned copper wire is a type of copper wire coated in a thin layer of tin. It is resistant to corrosion, lasts longer than normal wire, and is easier to solder.
Bare vs. Tinned Copper Wires
Is this AL wire or tinned copper? : r/askanelectrician
What is 'insulated' copper wire? - Quora
What Is Tin Copper Wire?
Tinned Copper VS Bare Copper - Pacer Group
Tinned Copper Wire vs. Bare Copper Wire: When Is It Best to Use Each O
Tinned Copper vs. Bare Copper Wire - International Wire
What is tinned copper wire? - Quora
Why Use Tinned Copper Wire?
Tinned copper & Bare copper