Which term describes a protective layer formed by applying solder to wire ends prior to joining?

• A. Tinning
• B. Wetting
• C. Capacitance
• D. Compression

Answer: (A)

Tinning is coating the wire ends with a thin layer of solder to protect the copper from oxidation and to improve solderability for a reliable joint. When you tin wires, you apply flux and heat the end so solder flows over the strands, creating a smooth, solder-coated tip that will readily fuse with the component lead or connector during assembly. That protective solder layer helps prevent fraying and ensures better wetting and flow when you actually make the joint.

Wetting describes how well solder spreads and adheres to a surface during soldering, which is part of the process but not the term for the pre-coated layer itself. Capacitance is an electrical property related to how much charge can be stored between conductors, and compression refers to a mechanical joining method—neither describes forming a protective pre-coating with solder.