The basic performance of connectors can be divided into three categories: mechanical performance, electrical performance, and environmental performance. Another important mechanical performance is the mechanical lifespan of the connector. Mechanical lifespan is actually a durability indicator. It is based on a cycle of engagement and separation, and is evaluated based on whether the connector can complete its connection function (such as contact resistance value) normally after the specified engagement and separation cycle. 1. In terms of connection function, insertion and extraction force is an important mechanical performance. Insertion and extraction forces are divided into insertion force and extraction force (also known as separation force), and their requirements are different. In relevant standards, there are provisions for maximum insertion force and minimum separation force, indicating that from a usage perspective, the insertion force should be small (resulting in structures with low insertion force LIF and no insertion force ZIF), and if the separation force is too small, it will affect the reliability of the contact. The insertion and extraction force and mechanical life of connectors are related to the contact structure (positive pressure size), the coating quality (sliding friction coefficient) of the contact area, and the accuracy of the contact arrangement dimensions (alignment).
The main electrical performance of electrical connectors includes contact resistance, insulation resistance, and electrical strength.
① High quality electrical connectors with high contact resistance should have low and stable contact resistance. The contact resistance of connectors varies from a few milliohms to tens of milliohms. ② The insulation resistance is an indicator that measures the insulation performance between the contact parts of an electrical connector and between the contact parts and the housing. Its magnitude ranges from several hundred megaohms to several hundred gigaohms. ③ Electrical strength, also known as withstand voltage or dielectric withstand voltage, is the ability to withstand the rated test voltage between connector contacts or between contacts and the housing. ④ Other electrical properties. Electromagnetic interference leakage attenuation is used to evaluate the electromagnetic interference shielding effect of connectors. Electromagnetic interference leakage attenuation is used to evaluate the electromagnetic interference shielding effect of connectors, and is generally tested in the frequency range of 100MHz~10GHz. For RF coaxial connectors, there are also electrical indicators such as characteristic impedance, insertion loss, reflection coefficient, and voltage standing wave ratio (VSWR). Due to the development of digital technology, a new type of connector called high-speed signal connector has emerged to connect and transmit high-speed digital pulse signals. Correspondingly, in terms of electrical performance, in addition to characteristic impedance, some new electrical indicators have also emerged, such as crosstalk, transmission delay, skew, etc.
3. Common environmental performance includes resistance to temperature, humidity, salt spray, vibration, and impact.
① At present, the maximum working temperature of heat-resistant connectors is 200 ℃ (except for a few high-temperature special connectors), and the minimum temperature is -65 ℃. Due to the heat generated by the current at the contact point during the operation of the connector, resulting in temperature rise, it is generally believed that the operating temperature should be equal to the sum of the ambient temperature and the contact temperature rise. In some specifications, the maximum temperature rise allowed for connectors at rated operating current is clearly specified. ② The intrusion of moisture and humidity can affect the insulation performance of the connection and corrode metal parts. The constant humidity and heat test conditions are relative humidity of 90% to 95% (up to 98% according to product specifications), temperature of+40 ± 20 ℃, and test time according to product specifications, with a minimum of 96 hours. The alternating humidity test is more rigorous. ③ When salt spray resistant connectors work in environments containing moisture and salt, their metal structural components and contact surface treatment layers may undergo electrochemical corrosion, affecting the physical and electrical performance of the connector. In order to evaluate the ability of electrical connectors to withstand this environment, a salt spray test is specified. It suspends the connector in a temperature controlled test chamber and sprays a specified concentration of sodium chloride solution with compressed air to form a salt spray atmosphere. The exposure time is specified in the product specifications and is at least 48 hours. ④ Vibration and impact resistance is an important performance of electrical connectors, particularly important in special application environments such as aviation and aerospace, railway, and road transportation. It is an important indicator for testing the robustness of the mechanical structure and electrical contact reliability of electrical connectors. There are clear regulations in the relevant experimental methods. The peak acceleration, duration, and waveform of the impact pulse, as well as the time of electrical continuity interruption, should be specified in the impact test. ⑤ Other environmental properties of electrical connectors include sealing (air leakage, liquid pressure), liquid immersion (resistance to deterioration of specific liquids), low air pressure, etc., depending on usage requirements.
