Connector Three Performance Details
The three major performance of the connector, namely, the basic performance, are divided into three categories: environmental performance, electrical performance and mechanical performance.
First, environmental performance: common environmental performance includes temperature resistance, humidity resistance and salt spray corrosion resistance.
1. Humidity resistance: the invasion of moisture will affect the insulation performance of the connector and rust the metal parts.Constant humid heat test conditions for relative humidity of 90% ~ 95% (according to the product specification, up to 98%), temperature + 40 + 20 ℃, the test time according to the provisions of the product for at least 96 hours.Alternating heat and humidity tests are more rigorous.
2, heat resistance, the connector of the highest working temperature is 200 ℃ (with the exception of a few special connector), and minimum temperature was 65 ℃.As the connector works, the current generates heat at the contact point, resulting in temperature rise. Therefore, it is generally believed that the working temperature should be equal to the sum of the ambient temperature and contact temperature rise.In some specifications, the maximum temperature rise allowed for the rated working current of the connector is explicitly specified.
3. Salt spray corrosion resistance: when the connector is working in an environment containing moisture and salt, the surface treatment layer of its metal structure parts and contact parts may produce electrochemical corrosion, which affects the physical and electrical properties of the connector.To evaluate the electrical connector's ability to withstand such an environment, salt spray tests are prescribed.It is to hang the connector in the temperature-controlled test box, with the specified concentration of sodium chloride solution with compressed air to form the atmosphere of salt fog, its exposure time is regulated by the product regulation, at least 48 hours.Other environmental performance: according to the application requirements, other environmental performance of electrical connector is sealing (air leakage, liquid pressure), liquid impregnation (resistance to particular liquid), low pressure, etc.
Second, electrical performance: mainly includes contact resistance, insulation resistance, current and electrical strength.
1. Current: Limited by the electrical connector and its terminated wires. Other electrical properties as well as electromagnetic interference leakage attenuation is to evaluate the electromagnetic interference shielding effect of the connector, generally tested in the frequency range of 100MHz~10GHz. For RF coaxial connectors, there are electrical indicators such as characteristic impedance, insertion loss, reflection coefficient, and voltage standing wave ratio (VSWR).
2. Insulation resistance: A measure of the insulation performance between the contacts of the electrical connector and between the contact and the outer casing, in the order of hundreds of megaohms to several gigaohms.
3. 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.
4. Resistance to electric strength or withstand voltage: characterizes the ability of the connector contacts or between the contact and the casing to withstand the rated test voltage, depending on the gap between the circuits (ie contact spacing and creepage distance) and the connector Insulation materials used in the process.
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. Correspondingly, in addition to the characteristic impedance, some new electrical indicators have appeared in terms of electrical performance. Such as crosstalk, delay, skew, etc.
Third, mechanical properties: mainly include positioning keys, insertion force, locking method, mechanical life, vibration and shock resistance.
The positioning key is a key structure selected to prevent mis-insertion of the connector. The insertion force is divided into the insertion force and the extraction force (the extraction force is also called the separation force), and the requirements of the two are different.
There is a maximum insertion force and a minimum separation force specification in the relevant standards, which indicates that the insertion force is small from the viewpoint of use, and if the separation force is too small, the reliability of the contact is affected. The insertion and extraction force and mechanical life of the connector are related to the coating quality (sliding friction coefficient) of the contact structure (positive pressure) and the dimensional accuracy (alignment) of the contact arrangement. The locking method is a safe and reliable connection method to prevent the vibration from causing the connector to separate, such as adding a safety fuse when the thread is connected. Mechanical life is another important mechanical property. Mechanical life is actually a durability indicator, which is called mechanical operation in GB5095. It is a cycle of one insertion and one extraction to determine whether the connector can normally complete its connection function (such as contact resistance value) after the specified insertion and removal cycle. Vibration and shock resistance are important mechanical properties. They are especially important in special applications such as aerospace and aerospace, railway and road transportation. Especially with the increase of aircraft or missile flight speed, vibration and shock are intensified, which may cause insulation installation board. Cracks, wires and joints break at the joints, and even cause the inserts to separate, especially when the resonance is more severe, causing the connector to fail. Peak acceleration, duration, and shock pulse waveform, as well as the time of electrical continuity interruption, should be specified in the impact test.