The basic performance of connectors can be divided *** three categories: mechanical performance, electrical performance and environmental performance. Another important mechanical property is the mechanical life of the connector. In practice, mechanical life is an index of durability, which is called mechanical operation in the national standard gb5095. It takes one ***ion and one pull-out as a cycle, and takes whether the connector can normally complete its connection function (such as contact resistance value) after a regular plug-in cycle as the basis for evaluation.
1. Mechanical performance as far as the connection function is concerned, the plugging force is an important mechanical performance. The pull-out force is divided *** ***ion force and pull-out force (also known as separation force), and their requirements are different. There are rules for maximum ***ion force and minimum separation force in relevant specifications, which indicates that from the perspective of application, the ***ion force should be small (thus the structure with low ***ion force LIF and no ***ion force ZIF), and if the separation force is too small, it will affect the reliability of contact. The plugging force and mechanical life of the connector are related to the contact structure (positive pressure), the coating quality of the contact part (sliding friction coefficient) and the dimensional accuracy (alignment) of the contact arrangement.
2. Electrical properties the main electrical properties of the connector include contact resistance, insulation resistance and electrical strength.
① Electrical connectors with high contact resistance should have low and stable contact resistance. The contact resistance of the connector varies from a few milliohms to tens of milliohms.
② Insulation resistance is an index to weigh the insulation performance between electrical connector contacts and between contacts and shell, and its order of magnitude ranges from hundreds of megaohms to hundreds of gigaohms.
③ Electrical strength, or voltage resistance and dielectric withstand voltage, is the ability to withstand the rated experimental voltage between the connector contacts or between the contacts and the shell.
④ Other electrical properties. Electromagnetic interference leakage attenuation is to evaluate the electromagnetic interference shielding effect of the connector. Electromagnetic interference leakage attenuation is to evaluate the electromagnetic interference shielding effect of the connector. It is generally tested in the frequency range of 100MHz ~ 10GHz. For RF coaxial connectors, there are also electrical indexes such as characteristic impedance, ***ion loss, reflection coefficient, 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, is presented. Accordingly, in terms of electrical performance, in addition to characteristic impedance, it also presents some new electrical indicators, such as crosstalk, transmission delay, skew and so on.
3. Environmental performance common environmental properties include temperature resistance, humidity resistance, salt spray resistance, vibration and impact resistance.
① At present, the maximum working temperature of the temperature resistant adapter is 200 ℃ (except for a few high-temperature special adapters), and the minimum temperature is - 65 ℃. When the adapter works, the current generates heat at the contact point, resulting in temperature rise. Therefore, it is generally considered that the working temperature should be equal to the sum of ambient temperature and contact temperature rise. In some standards, the maximum allowable temperature rise of the adapter under the rated working current is clearly regulated.
② The invasion of moisture resistance will affect the bonding H insulation performance and rust the metal parts. The constant damp heat test conditions are 90% ~ 95% relative humidity (up to 98% according to the product standard), temperature + 40 ± 20 ℃, and the test time is 96 hours at least according to the product rules. The alternating damp heat experiment is more rigorous.
③ When the salt spray resistant adapter works in the environment containing moisture and salt, its metal structure and contact surface treatment layer may produce electrochemical corrosion, affecting the physical and electrical properties of the adapter. In order to evaluate the ability of the electrical connector to withstand this environment, the salt spray experiment was carried out. The adapter is suspended in a temperature controlled experimental box, and the sodium chloride solution with regular concentration is sprayed with compressed air to form a salt spray atmosphere. The exposure time is regulated by the product standard, which is at least 48 hours.
④ Vibration and shock resistance to vibration and shock is an important performance of electrical adaptor, which is particularly important in special application environments, such as aviation and aerospace, railway and highway transportation. It is an important index to test the consolidation of mechanical structure and electrical contact reliability of electrical adaptor. There are clear rules in the relevant experimental methods. In the impact test, the peak acceleration, duration, impact pulse waveform and the time of electrical continuity infill shall be regular.
⑤ Other environmental properties are based on the application requirements. Other environmental properties of the electric connector include tightness (air leakage, liquid pressure), liquid immersion (anti vice ability of specific liquid), low air pressure, etc.