Electronic Connector Reliability

An electronic connector system is one of the most critical elements in an electronics package, providing both the mechanical and electrical support necessary for electronics to operate effectively. Electrical connectors facilitate the transmission of electrical signals between components and packaging levels within a unit, while also creating mechanical linkages for the packaging structure. Ideally, an individual connector serves as a separable interface between two subsystems without introducing unwanted effects, such as signal distortion or power loss. As a separable device, its mating interface can be detached, allowing for independent manufacturing of parts for assembly at a central location and greater ease of component maintenance and upgrading. For these reasons, connector reliability is an important factor in electronic systems and can have a major influence on product performance.

One of the major factors affecting electrical connector reliability involves time-dependence, which is the calculation of a connector’s failure rate measured relative to the length of time the connector is in operation. Time-dependant problems are the most common source of connector malfunctions and breakdowns, and are of key significance to connector system designers. Another major reliability factor is plug-dependence, which is the result of the amount of actuations and deactuations that occur during connector operations. Most plug-dependant failures can either be reversed through additional connector insertions or require repair or replacement in order for the system to perform effectively.

Connector Failure Rates

In general, a connector’s expected performance depends on its design characteristics and operating environment. A standard connector system operating in normal commercial parameters can expect one failure for every several thousand successful contacts over the course of its lifespan, while plug-dependant performance for highly durable connectors can be as reliable as only ten failures for every million contacts under normal conditions. Achieving this level of reliability often requires the maintenance of a gas-tight, non-corrosive contact interface throughout a connector’s lifespan because airborne dust and other particulate matter can be a persistent source of plug-dependant problems. The Reliability Information Analysis Center provides technical data on connector failure rate models.

Connector Metallurgy

Most high-quality connectors typically feature a noble metal, such as palladium, plated over a nickel diffusion barrier, which is intended to prevent the connector base metal from diffusing through the plating to contaminate and degrade the contact interface. The material used for the contact interface needs to be thick enough to reduce the risk of operational wear while presenting a corrosion-resistant mating surface for contact. The required plating thickness usually depends on the operating environment, the capabilities of the plating method, and the amount of mating and unmating cycles expected over the device’s lifespan.

When functioning in more corrosive settings, connectors require sealing or enough plating thickness to maintain a non-porous contact area. Depending on the porous properties of the plating process, additional plating layers may be needed to prevent plating pores from exposing the contact base materials. Less expensive, non-noble metals can be used as plating materials for a contact interface in applications that do not require contact motion during operations and are not in a corrosive atmosphere.

Contact and Connector Performance

An effective connector system provides an adequate level of contact force to maintain a gas-tight link at the contact interface and to aid in displacing particles and oxides during a mating cycle. In addition, the degree of relative sliding between mated pairs should normally move particles aside to expose the metallurgy at the contact interface. The balance between the contact force and the sliding action can be a major influence on the connector system’s reliability and cost, while the number of contact interfaces can affect the rate of time- and plug-dependant failure. Increasing the amount of contacts or using multiple-sided mating contacts can reduce the risk of failure. Although it may hinder signal capability, having a close ratio of ground contacts to signal contacts can further improve electrical connector reliability.

Compatibility and Packaging

In many cases, electrical connectors are joined to printed wiring boards at the same time other components are mounted, meaning the connectors must be able to tolerate the chemical processes and temperatures involved in the joining process. Introducing resistant materials to make the connectors compatible with this assembly process can increase the cost of a connector system and must be balanced against packaging density requirements. Connectors with a low level of relative sliding are at a greater risk of failure if the package allows deflections to occur. These deflections can be compensated through the use of tie plates or board stiffeners that improve rigidity, and these considerations may play a prominent role in packaging design.