I. Three main parameters of electrical connectors
1. Shielding
In modern electrical and electronic equipment, the increasing density of components and their interconnected functions have imposed strict limitations on electromagnetic interference. Therefore, connectors are often enclosed in metal housings to prevent internal electromagnetic energy radiation or interference from external electromagnetic fields. At low frequencies, only magnetic materials can provide significant shielding against magnetic fields. In this case, certain regulations apply to the electrical continuity of the metal housing, specifically the housing contact resistance. Safety parameters
2. Insulation resistance
Insulation resistance refers to the resistance value exhibited when a voltage is applied to the insulating part of a connector, causing leakage current to flow into or around the surface of the insulating part. It is mainly affected by factors such as the insulating material, temperature, humidity, and contamination. The insulation resistance values provided on connector samples are generally specifications under standard atmospheric conditions; under certain environmental conditions, the insulation resistance value may decrease to varying degrees. It is also important to pay attention to the test voltage value for insulation resistance. According to the formula Insulation Resistance (MΩ) = Voltage applied to the insulator (V) / Leakage Current (μA), applying different voltages will yield different results. In connector testing, the applied voltage is generally available in three ranges: 10V, 100V, and 500V.
3. Pressure resistance
Withstand voltage is the critical voltage that a contact pair can withstand between its insulated parts or between an insulated part and ground within a specified time without breaking down. It is mainly affected by the contact pair spacing, creepage distance and geometry, insulating material, as well as ambient temperature, humidity, and atmospheric pressure.
II. Failure Modes of Electrical Connectors to the End of Their Service Life
In the quality control of electrical connectors, users often encounter two dilemmas:
(1) Believing that electrical connectors are important components for connecting devices/components/systems, and therefore considering all electrical connectors as critical components, leads to a lack of focus and an excessively broad scope of attention, which violates the quality management objective of "achieving low-cost operation";
(2) Compared with mainstream international manufacturers, the overall quality and technical level of domestic electrical connectors still lag significantly behind, especially in standardized production management. This inadequacy results in inconsistent quality of domestically produced electrical connectors, with frequent and recurring low-level quality problems. This disrupts quality management efforts, preventing limited resources from being effectively focused on improving connector reliability. Therefore, understanding and studying common failure modes of electrical connectors is fundamental to overcoming the challenges in quality management and is also the basis for connector selection, quality inspection, use (including processing), and analysis by users.
Reasons for failure due to reaching the end of service life
Based on the main causes of failure of electrical connectors to the end of their service life, the service life of electrical connectors is a comprehensive consideration of wear and fatigue, while the storage life of electrical connectors is a comprehensive consideration of oxidation, moisture and aging, and the objects of consideration are the decline in mechanical and electrical performance.
Among various environmental stresses, failures caused by temperature, humidity, and vibration account for 86% of all environmental stress-induced failures. When analyzing failure modes such as wear, fatigue, oxidation, and aging, these three factors must be considered, and their correlation must be taken into account.
The most significant impact is wear, which can be categorized as: oxidation wear, seizing wear, field wear, abrasive wear, surface fatigue wear, and fretting wear.
