Topcoat is bare (untinned) copper wire, stranded, then coated with pure tin.
Topcoat refers to a conductor made from bare, untinned copper wire that is first stranded and then coated with pure tin over the assembled strand. In contrast to using individually tinned strands, the topcoat process applies the tin after stranding, so the tin coats the outer surface of the finished stranded conductor. This provides a tin surface for solderability and corrosion resistance on the completed conductor.
By tinning after stranding rather than before, the topcoat approach coats the conductor as a unit, which can be economical and provides the solderable, corrosion-resistant outer surface that tin offers. The underlying strands remain bare copper within the bundle.
In commercial and industrial wire, topcoated conductors provide a tinned outer surface for solderability and corrosion resistance. Recognizing the term helps in understanding how tinning can be applied to stranded conductors.
Because tinning after stranding rather than before coats the conductor as a unit, the topcoat approach can be economical and provides the solderable, corrosion-resistant outer surface that tin offers, while the underlying strands remain bare copper within the bundle.
Recognizing how a tin topcoat aids soldering and resists corrosion helps customers match conductors to their termination and environmental needs, since topcoated stranded conductors offer a solderable, corrosion-resistant outer surface for reliable terminations in commercial and industrial systems.
At Windy City Wire, an understanding of conductor finishes, including topcoat tinning, supports the selection of wire suited to an application. Recognizing how a tin topcoat aids soldering and resists corrosion helps customers match conductors to their termination and environmental needs.