Connector knowledge The basic performance of connectors can be divided into three categories: mechanical performance, electrical performance and environmental performance. Another important mechanical property is the mechanical life of the connector. Mechanical life is actually a durability indicator, which is called mechanical operation in the national standard GB5095. It takes one insertion and one extraction as a cycle, and whether the connector can normally complete its connection function (such as contact resistance value) after the specified insertion and removal cycle is used as the judgement basis.

1. Mechanical performance As far as the connection function is concerned, the insertion and extraction force 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 properties The main electrical properties of the connector include contact resistance, insulation resistance and dielectric strength.

① Electrical connectors with high-quality contact resistance should have low and stable contact resistance. The contact resistance of the connector ranges from a few milliohms to tens of milliohms.

②Insulation resistance is a measure of the insulation performance between the contacts of electrical connectors and between the contacts 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.

④Other electrical properties.

Electromagnetic interference leakage attenuation is to evaluate the electromagnetic interference shielding effect of the 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 radio frequency 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, 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 (crosstalk), transmission delay (delay), time lag (skew), etc.

3. Environmental performance Common environmental performance includes temperature resistance, humidity resistance, salt spray resistance, vibration and shock resistance.

①Temperature resistance At present, the maximum working temperature of 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, which 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.

②The intrusion of moisture resistance will affect the insulation performance of the connection h and rust the 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.

③When the salt spray resistant connector works 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 connector in a temperature-controlled test box and sprays out a sodium chloride solution with a specified concentration with compressed air to form a salt spray atmosphere. The exposure time is specified by the product specification, at least 48 hours.

④Vibration and shock Vibration and shock resistance is an important performance of electrical connectors, especially in special application environments such as aviation and aerospace, railway and road transportation. It is to test the robustness of the electrical connector’s mechanical structure and reliable electrical contact. An important indicator of sex. 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.

⑤Other environmental performance According to the requirements of use, other environmental performances of the electrical connector include air tightness (air leakage, liquid pressure), liquid immersion (resistance to specific liquids), low air pressure, etc.