The performance of terminal wire connectors can generally be divided into three categories: mechanical performance, electrical performance and environmental performance.
1. Mechanical properties. As far as the function of the terminal wire connector is concerned, the plugging force of the product structure design is an important mechanical performance. Insertion and extraction force is divided into insertion force and extraction force (extraction force is also called separation force), the requirements of the two are different. There are provisions for maximum insertion force and minimum separation force in the relevant standards, which shows that from the perspective of use, the insertion force should be small (there are low insertion force LIF and no insertion force ZIF structure), and if the separation force is too small, It will affect the reliability of the contact. The plug-in force and mechanical life of the connector are related to the contact structure (positive pressure), the coating quality of the contact part (the sliding friction coefficient) and the dimensional accuracy of the contact arrangement (alignment).
2.Electrical performance. The main electrical properties of terminal wire connectors include contact resistance, insulation resistance and dielectric strength.
(1) Contact resistance. High-quality electrical connectors should have low and stable contact resistance. The contact resistance of the connector ranges from a few milliohms to tens of milliohms.
(2) Insulation resistance. The index to measure the insulation performance between the contacts of the electrical connector and between the contact and the shell, and its magnitude ranges from hundreds of megohms to several thousand megohms.
(3) Dielectric strength, or withstand voltage, dielectric withstand voltage, is the ability to withstand the rated test voltage between the connector contacts or between the contacts and the shell.
(4) Other electrical properties.
The electromagnetic interference leakage attenuation is to evaluate the electromagnetic interference shielding effect of the terminal line connector, and the electromagnetic interference leakage attenuation is to evaluate the electromagnetic interference shielding effect of the connector, and it is generally tested in the frequency range of 100MHz~10GHz.
For RF coaxial terminal line connectors, there are electrical indicators such as characteristic impedance, insertion loss, reflection coefficient, and voltage standing wave ratio (VSWR). Due to the development of digital technology, in order to connect and transmit high-speed digital pulse signals, a new type of connector, namely high-speed signal connector, has appeared. Accordingly, in terms of electrical performance, in addition to characteristic impedance, some new electrical indicators have also appeared , Such as crosstalk, transmission delay, time lag, etc.
3.Environmental performance. Common environmental properties include resistance to temperature, humidity, salt spray, vibration and shock.
(1) Temperature resistance. At present, the maximum working temperature of terminal wire connectors is 200℃ (except for a few high-temperature special connectors), and the lowest temperature is -65℃. When the connector is working, the current generates heat at the contact point and causes a temperature rise. Therefore, it is generally believed that the working temperature should be equal to the sum of the ambient temperature and the temperature rise of the contact point. In some specifications, the maximum temperature rise allowed by the connector under the rated operating current is clearly specified.
(2) Humidity resistance. The intrusion of moisture will affect the insulation performance of the connection and rust metal parts. Constant humidity test conditions are relative humidity 90%~95% (according to product specifications, up to 98%), temperature +40±20℃, test time is as per product specifications, at least 96 hours. The alternating damp heat test is more stringent.
(3) Salt spray resistance. When the connector is working in an environment containing moisture and salt, the surface treatment layer of its metal structural parts and contact parts may produce galvanic corrosion, which affects the physical and electrical properties of the connector. In order to evaluate the ability of electrical connectors to withstand this environment, a salt spray test is specified.
It hangs the terminal wire connector in a temperature-controlled test box and sprays it with compressed air with a specified concentration of sodium chloride solution to form a salt fog atmosphere. The exposure time is specified by the product specification, at least 48 hours.
(4) Vibration and shock. Vibration and shock resistance is an important performance of electrical connectors. It is 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 electrical connectors' mechanical structure and electrical contact reliability. . There are clear regulations in the relevant test methods. In the shock test, the peak acceleration, duration and shock pulse waveform, as well as the interruption time of electrical continuity should be specified.
(5) Other environmental performance. According to the requirements of use, other environmental properties of the electrical connector include airtightness (air leakage, liquid pressure), liquid immersion (ability to resist specific liquids), low air pressure, etc.