A single car has upward of 700 connectors, and that number is expected to increase to thousands per vehicle with the proliferation of electric vehicles (EVs) and autonomous driving technology. Electronics and electrical systems are increasingly replacing mechanical ones as designers add modern comforts that consumers demand, including infotainment systems and safety features.
However, increasing electrification means more connectors and the potential for failures that are significantly more serious than a quiet radio. If a connector loses signal in an autonomous vehicle, critical safety features such as braking or steering could fail with potentially fatal consequences.
The risk of electrical system failures is already apparent. In 2012, there were about 20 recalls related to electrical component failures, and in 2016 this number grew to almost 60, according to a report by AlixPartners. Something seemingly as small as connector reliability could mean the difference between safe operation and dangerous, costly recalls. As connectors and electrical systems evolve and become more sensitive to resistance changes, dielectric lubricants must progress to keep up with application needs.
One of the most common reasons for electric connector failure is fretting corrosion – wear that forms on electrical connectors and contacts when they are exposed to micromotions from vibration and/or thermal expansion caused by heating or cooling cycles. Micromovements wear through metal coatings into the base material that then oxidize, eventually creating an open connection and ultimately, power failure or signal loss. As this oxide layer builds up, it acts as an insulator between the contacts, creating an open circuit and voltage drop across the terminal.
Sometimes un-mating and re-mating connectors is enough to solve intermittent power failures. However, unless a dielectric lubricant is applied, the connector will continue to wear and will eventually oxidize and corrode. Dielectric grease has two primary benefits:
- The grease reduces physical wear between the connecting surfaces as they undergo micromotions and fretting wear. This wear reduction preserves the connectors’ layered coatings designed to prevent oxidation and minimize resistance.
- It insulates the system from the surrounding environment, preventing insulative oxide layer buildup, which increases resistance and signal loss. Although the dielectric lubricant is non-conductive, it still allows the microscopic asperities of the contacts to transfer signal and power, while filling in the valleys of the connectors where oxides and wear debris can form. Dielectric properties become especially important in multi-pin connectors, eliminating the possibility of a short between pins.
Insertion force will become more important with EVs and autonomous vehicles (AVs) – especially for those who manufacture large multi-pin connectors and wire harnesses. These connectors require more force to mate the connections, increasing assembly technicians’ risk of musculoskeletal disorders. Dielectric grease reduces the amount of force required to mate connectors by lowering friction between the connectors’ two sides. Lower insertion force reduces physical strain on assembly line workers, which can reduce worker compensation claims.
Aside from fretting protection, dielectric greases also protect against corrosion, reduce insertion force, prevent water washout, and seal connectors from environmental factors, keeping out water, dirt, and other corrosive elements that can lead to power failure.
Brake pedal sensors, wheel speed sensors, and sensors for airbag deployment are a few examples where an instantaneous short circuit or a communication network fault due to signal loss can be catastrophic. Applying grease during production ensures a solid connection for the life of the terminal to avoid costly and safety-critical recalls.