The basic performance of connectors can be divided into three categories: mechanical performance, electrical performance and environmental performance.
1. Mechanical properties. As far as the connection function is concerned, the insertion and extraction force is an important mechanical property. The pull-in force is divided into insertion force and pull out force, and their requirements are different. In the relevant standards, there are provisions for large insertion force and small separation force, which indicates that the insertion force is small, and if the separation force is too small, it will affect the contact reliability. Another important mechanical property is the mechanical life of the connector. Mechanical life is a kind of durability index, which is called mechanical operation in GB 5095. It takes one insertion and one pull-out as a cycle, and judges whether the connector can normally complete its connection function after the specified plug-in cycle.
The pulling force and mechanical life of the connector are related to the coating quality of the contact structure and the size accuracy of the contact arrangement.
2. Electrical performance. The main electrical properties of the connector include contact resistance, insulation resistance and electrical strength.
① Contact resistance. High-quality electrical connectors shall have low and stable contact resistance. The contact resistance of the connector varies from a few milliohms to tens of milliohms.
② Insulation resistance. The index to measure the insulation performance between the contacts and between the contacts and the shell of the electrical connector is in the order of hundreds to gigaohms.
③ Electric strength. Or voltage and dielectric withstand voltage, is the ability to withstand rated test voltage between connector contacts or between contacts and shell.
④ Other electrical performance.
EMI leakage attenuation is to evaluate the EMI shielding effect of the connector, and EMI leakage attenuation is to evaluate the EMI shielding effect of the connector, which is generally tested in the frequency range of 100MHz ~ 10GHz. For RF coaxial connectors, there are also electrical indexes such as characteristic impedance, insertion loss, reflection coefficient and VSWR. Due to the development of digital technology, to connect and transmit high-speed digital pulse signals, a new type of connector, namely high-speed signal connector, has emerged.
Correspondingly, in terms of electrical performance, in addition to the characteristic impedance, there are also some new electrical indicators, such as crosstalk hysteresis.
3. Environmental performance. Common environmental properties include temperature resistance, humidity resistance, vibration and impact resistance.
① Temperature resistance. At present, the high working temperature of the connector is 200 ℃, and the low temperature is - 65 ℃. Due to the heat generated by the current at the contact point when the connector works, resulting in temperature rise, it is generally considered that the working temperature should be equal to the sum of the ambient temperature and the contact temperature rise. In some specifications, the allowable high-temperature rise of the connector underrated working current is specified.
② Humidity resistance. The invasion of moisture will affect the insulation performance of connection h and rust the metal parts. The constant humidity and heat test conditions are relative humidity 90% ~ 95%, temperature + 40 ± 20 ℃, and the test time shall be at least 96 hours according to the product regulations. The alternative damp heat test is more severe.
③ Salt fog resistance. When the connector works in the environment containing moisture and salt, the surface treatment layer of its metal structure and contact parts may produce electrochemical corrosion, which may affect the physical and electrical properties of the connector. To evaluate the ability of an electrical connector to withstand this environment, a salt spray test is specified. The connector is suspended in a temperature-controlled test chamber to form a salt spray atmosphere, and its exposure time is specified by the product specification, at least 48 hours.
④ Vibration and impact. Vibration and shock resistance is an important performance of the electrical connector, which is an important index to test the mechanical structure of the electrical connector and electrical contact reliability. There are clear provisions in relevant test methods. Peak acceleration and interruption time of electrical continuity shall be specified in the impact test.
⑤ Other environmental performance. According to the use requirements, the other environmental performance of the electrical connector includes tightness, low air pressure, etc.
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