Microwaves & RF

JJD: Why is oxidation and corrosion an issue with coaxial cables?

CK: Oxidation and corrosion can be significant problems on copper and aluminum conductors. These oxides inhibit solderability, degrade the electrical performance of the conductor, and—if left to grow unchecked­can compromise the device’s mechanical or electrical integrity. Such oxides grow most rapidly in warm and moist environments. They require the presence of oxygen in the atmosphere to corrode.

JJD: What methods exist to protect coaxial cable conductors from oxidation?

CK: Probably the most common means of protecting these materials from oxidation is through the use of barrier coatings. These coatings prevent oxygen from reaching the surface of the conductor. Such coatings include the common electroplated surface layers. For example, gold, silver, and tin are commonly used to protect less noble metals from corrosion, preserve or enhance solderability, and provide a pleasing appearance. The coatings must be thick enough to provide protection for the service life of the conductor. Often, an intermediate layer like nickel is used to reduce porosity and inhibit the migration of the basis metal to the surface.