Basic parameters of commonly used connectors
The basic performance of connectors can be divided into three categories:
Mechanical behavior
Electrical properties
Environmental performance
Mechanical behavior
1. As far as the connection function is concerned, the insertion force is an important mechanical property. 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. In the relevant standards, there are provisions for the maximum insertion force and the minimum separation force, which means that from the point of view of use, the insertion force should be small (thereby a structure with low insertion force LIF and no insertion force ZIF), and if the separation force is too small, will affect the reliability of the contact.
2. Another important mechanical property is the mechanical life of the connector. Mechanical life is actually a durability index, which is called mechanical operation in the national standard GB5095. It takes one insertion and one extraction as a cycle, and judges whether the connector can normally complete its connection function (such as contact resistance value) after the specified insertion and extraction cycle.
3. The plug-in force and mechanical life of the connector are related to the contact structure (positive pressure), the coating quality (sliding friction coefficient) of the contact part, and the dimensional accuracy (alignment) of the contact arrangement.
Electrical properties
①Contact resistance High-quality electrical connectors should have low and stable contact resistance. The contact resistance of connectors varies from a few milliohms to tens of milliohms.
②Insulation resistance is an indicator of the insulation performance between the contacts of the electrical connector and between the contacts and the shell, and its order of magnitude ranges from hundreds of megohms to several gigaohms.
③ Dielectric strength or withstand voltage, dielectric withstand voltage, is to characterize the ability of the connector to withstand the rated test voltage between the contacts or between the contacts and the shell.
④Other electrical properties:
The 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, which 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, in order to connect and transmit high-speed digital pulse signals, some new connectors such as high-speed signal connectors have 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 delay (skew) and so on.
Environmental performance
①Temperature resistance At present, the maximum working temperature of the connector is 200°C (except for a few high-temperature special connectors), and the minimum temperature is -65°C. Since the current generates heat at the contact point when the connector is working, resulting in a temperature rise, it is generally believed that the operating 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 at the rated operating current is clearly specified.
②The intrusion of moisture resistance will affect the insulation performance of the connection h and corrode metal parts. The constant damp heat test conditions are relative humidity 90%~95% (according to product specifications, up to 98%), temperature +40±20℃, and the test time is at least 96 hours according to product regulations. The alternating damp heat test is more severe.
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