Terminal Connector Knowledge Terminal connector basic performance can be divided into three categories: mechanical, electrical and environmental performance. Another important mechanical property is the mechanical life of the terminal connector. Mechanical life is actually a durability indicator, which is called mechanical operation in GB5095. It is a cycle of one insertion and one extraction, so as to judge whether the terminal connector can complete its connection function normally after the specified insertion and removal cycle.
1. Mechanical properties In terms of the connection function, the insertion force is an important mechanical property. The insertion force is divided into the insertion force and the extraction 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 force and mechanical life of the terminal connector are related to the structure of the contact, the plating quality of the contact portion (sliding friction coefficient), and the dimensional accuracy (alignment) of the contact arrangement.
2. The main electrical properties of the electrical performance terminal connectors include contact resistance, insulation resistance and electrical strength.
1 Contact resistance High quality electrical terminal connectors should have low and stable contact resistance. The contact resistance of the terminal connectors ranges from a few milliohms to tens of milliohms.
2 Insulation resistance is an indicator of the insulation performance between the contacts of the electrical terminal connectors and between the contacts and the casing, which is on the order of hundreds of megaohms to several gigaohms.
3 Resistance to electric strength, or withstand voltage, dielectric withstand voltage, is the ability to characterize the rated test voltage between the terminal connector contacts or between the contacts and the housing.
4 other electrical properties. Electromagnetic interference leakage attenuation is an evaluation of the electromagnetic interference shielding effect of the terminal connector. The electromagnetic interference leakage attenuation is an evaluation of the electromagnetic interference shielding effect of the terminal connector, and is generally tested in the frequency range of 100 MHz to 10 GHz. For RF coaxial terminal connectors, there are electrical specifications 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 terminal connector, namely high-speed signal terminal connector, has appeared. Accordingly, in addition to the characteristic impedance, some new features have appeared in electrical performance. Electrical indicators such as crosstalk, transmission delay, time lag, etc.
3. Environmental performance Common environmental properties include temperature resistance, moisture resistance, salt spray resistance, vibration and shock.
1 Temperature resistance The current terminal connector has a maximum operating temperature of 200 ° C and a minimum temperature of -65 ° C. Since the current generates heat at the contact point when the terminal connector is in operation, resulting in a temperature rise, it is generally considered that the operating temperature should be equal to the sum of the ambient temperature and the junction temperature rise. In some specifications, the maximum temperature rise allowed by the terminal connector at rated operating current is specified.
2 Intrusion of moisture-resistant moisture will affect the insulation performance of the joint h and corrode metal parts. The constant damp heat test conditions are relative humidity of 90% to 95% and temperature of +40 ± 20 ° C. The test time is specified by the product and is at least 96 hours. The alternating heat and humidity test is more stringent.
3 Salt-tolerant terminal connectors When working in an environment containing moisture and salt, the metal structural parts and the surface treatment layer of the contact parts may cause galvanic corrosion and affect the physical and electrical properties of the terminal connectors. In order to evaluate the ability of electrical terminal connectors to withstand such environments, a salt spray test is specified. It suspends the terminal connector in a temperature-controlled test chamber and sprays it with compressed air at a specified concentration of sodium chloride solution to form a salt spray atmosphere. The exposure time is specified by the product specification for at least 48 hours.
4 Vibration and shock Resistance to vibration and shock is an important performance of electrical terminal connectors. It is especially important in special applications such as aerospace and aerospace, railway and road transportation. It is to verify the robustness and electrical structure of the mechanical structure of electrical terminal connectors. An important indicator of contact reliability. There are clear regulations in the relevant test methods. Peak acceleration, duration, and shock pulse waveforms, as well as the time of electrical continuity interruption, should be specified in the impact test.
5 Other environmental performance According to the use requirements, other environmental properties of the electrical terminal connector are also sealed, liquid impregnated, low air pressure and the like.
