Tin-Zinc and Other Glenair Material Innovations

Plating for Conductivity

In our electrical interconnect industry, the problems associated with corrosion are compounded by the need to produce parts that are electrically conductive. As we all know, it is the conductive properties of plated connectors and backshells which prevent electromagnetic interference (EMI) from disrupting the flow of data throughout the interconnect system. To prevent EMI from

Corrosion Process The

Cable shielding is grounded to conductively-plated connectors to prevent EMI

permeating into the system, conductive cable shielding is grounded to plated connectors and accessories to take the unwelcome EMI harmlessly to ground. If metal connectors and accessories could be produced without the need for conductive surface platings, corrosion in interconnect systems would be a much easier problem to resolve. Conductive surface platings themselves significantly compound the difficulty of preventing interconnect system corrosion. All matter is electrical by nature. Everything—from your body’s nervous system to the earth itself—has electrical properties since all matter is made up of atoms which in turn are composed of protons, neutrons, and electrons. The center, or nucleus of the atom, is composed of positively charged protons and neutral neutrons. The process of corrosion takes place at this most basic molecular level. To be a bit more exact, the corrosion process is electrochemical in nature; for the process to occur several specific conditions must be met, and not all are solely electrical: • There must be a positive or anodic area, the “anode.” • There must be a negative or cathodic area, the “cathode.” • There must be a path for ionic current flow, the “electrolyte.” • There must be a path for electronic current flow, which is normally a “metallic path.” The electrical pressure between the anode and the cathode results in a migration of electrons from one to the other along the metallic path. With the loss of electrons, positively-charged atoms remain at the anode, combining with negatively-charged ions in the environment to form, in the case of steel parts, ferrous hydroxide, or rust. In most interconnect applications the role of the ionic current flow is played by the atmosphere, rain, or salt spray on ships. The rate at which metal is removed by the corrosive process is measured in Mass Loss per Unit Area, and is driven by current density (Microamp per Centimeter Square). In interconnect applications the conductor for this electrical current can be the mating point of the various subcomponents—such as fasteners, bands and braids—or the threaded interface between the backshell and connector. But the metallic path for the current flow can also be between the shell of the component and its own metallic surface plating.

Anode

Corrosion

Ionic current flow

Electronic current flow

Cathode

The electrochemical corrosion process: Electrons migrate along the metallic path from the Anode to the Cathode. Positively-charged atoms remain in the anode and combine with negatively-charged ions in the environment to form rust.

QwikConnect • April 2023