Characterization of RF Micro-Coaxial Cable Insertion Loss Degradation
RF micro-coaxial insertion loss escalates through skin-depth resistance, dielectric loss tangent shifts, mechanical flex displacement, and atmospheric oxidation.
Galvanic Corrosion
Meaning
Electrochemical degradation results from the electrical contact of two dissimilar metals in the presence of an electrolyte. In the context of electronic enclosures or connectors, galvanic corrosion occurs when moisture acts as a bridge for ion transfer between metals with different electrode potentials. The less noble metal becomes the anode and loses mass as it oxidizes.
This process continues until the anode is consumed or the electrolyte is removed.
Potential Difference
Metals are ranked on a galvanic series that indicates their likelihood to react when paired. When the gap between the values of two metals is large, galvanic corrosion accelerates. Engineers select plating materials like gold or nickel to reduce the voltage gap between a connector and its mounting surface.
Environmental Barrier
Seals and gaskets prevent the entry of water or salt spray that triggers the reaction. Without a liquid medium to carry the ions, galvanic corrosion cannot proceed even between incompatible metals. Hermetic enclosures or potting compounds act as the primary defense in outdoor or marine deployments where humidity is constant.
Material Compatibility
Assembly logic dictates that the smaller part should be the more noble metal. If a small screw is anodic to a large housing, galvanic corrosion will destroy the screw quickly. Using stainless steel fasteners with aluminum frames requires a coating or an insulating washer to break the electrical path.