The fundamental performance characteristics of connectors can be categorized into three main types: mechanical performance, electrical performance, and environmental performance. Another important mechanical property is the mechanical life of the connector. Mechanical life is essentially a durability indicator; in the Chinese national standard GB5095, it is referred to as "mechanical operation." One insertion and one withdrawal constitute a single cycle, and the evaluation criterion is whether the connector can still perform its intended connection function (e.g., maintaining specified contact resistance) after a prescribed number of mating cycles.
1. Mechanical Performance – With regard to connection functionality, insertion and extraction force is a critical mechanical characteristic.
Insertion and extraction forces consist of insertion force and withdrawal force (also called separation force), which have different requirements. Relevant standards specify maximum insertion force and minimum separation force. From a usability perspective, insertion force should be low (leading to designs such as Low Insertion Force—LIF—and Zero Insertion Force—ZIF connectors). However, if the separation force is too low, it may compromise contact reliability. The insertion/extraction force and mechanical life of a connector are influenced by the contact structure (normal force magnitude), plating quality at the contact surfaces (coefficient of sliding friction), and dimensional accuracy of contact alignment (mating precision).
2. Electrical Performance – The primary electrical characteristics of connectors include contact resistance, insulation resistance, and dielectric strength.
① Contact Resistance: High-quality electrical connectors should exhibit low and stable contact resistance. Typical contact resistance values for connectors range from a few milliohms to several tens of milliohms.
② Insulation Resistance: This measures the insulation performance between contacts and between contacts and the connector housing. Values typically range from hundreds of megaohms to several gigaohms.
③ Dielectric Strength (also known as Withstand Voltage or Breakdown Voltage): This characterizes the connector’s ability to withstand a specified test voltage between contacts or between contacts and the housing without breakdown.
④ Other Electrical Characteristics: Electromagnetic interference (EMI) leakage attenuation is used to evaluate a connector’s EMI shielding effectiveness and is typically measured over a frequency range of 100 MHz to 10 GHz. For RF coaxial connectors, additional electrical parameters include characteristic impedance, insertion loss, reflection coefficient, and voltage standing wave ratio (VSWR). With the advancement of digital technology and the need to transmit high-speed digital pulse signals, a new class of connectors—high-speed signal connectors—has emerged. Accordingly, new electrical performance metrics beyond characteristic impedance have become relevant, such as crosstalk, propagation delay, and skew.
3. Environmental Performance – Common environmental performance characteristics include temperature resistance, humidity resistance, salt spray resistance, vibration, and shock.
① Temperature Resistance: Currently, the maximum operating temperature for most connectors is 200°C (excluding a few specialized high-temperature connectors), with a minimum of -65°C. During operation, current flow through contact points generates heat, causing a temperature rise. Therefore, the actual operating temperature is generally considered the sum of ambient temperature and contact-point temperature rise. Some specifications explicitly define the maximum allowable temperature rise under rated current conditions.
② Humidity Resistance: Moisture ingress can degrade insulation performance and cause corrosion of metal components. Standard steady-state damp-heat test conditions involve 90%–95% relative humidity (up to 98% per product specifications) at +40±20°C, with a minimum test duration of 96 hours as defined by product standards. Alternating damp-heat tests are even more stringent.
③ Salt Spray Resistance: When connectors operate in environments containing moisture and salt, electrochemical corrosion may occur on metal structural parts and surface finishes of contacts, adversely affecting both physical and electrical performance. To evaluate this resistance, salt spray testing is mandated. In this test, connectors are suspended in a temperature-controlled chamber and exposed to a salt fog atmosphere generated by atomizing a specified concentration of sodium chloride solution with compressed air. Exposure duration is defined by product specifications, with a minimum of 48 hours.
④ Vibration and Shock Resistance: These are critical performance attributes for electrical connectors, especially in demanding applications such as aerospace, aviation, railway, and automotive transportation. They serve as key indicators of both mechanical robustness and electrical contact reliability. Relevant test standards clearly specify test parameters. In shock testing, peak acceleration, duration, pulse waveform, and allowable interruption time of electrical continuity must all be defined.
⑤ Other Environmental Characteristics: Depending on application requirements, additional environmental performance criteria may include sealing capability (air leakage, liquid pressure resistance), liquid immersion resistance (resistance to specific fluids), and low-pressure (altitude) performance.
2025-10-09
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