How the connector works
You may not know more about connectors. The so-called connector is two or several containers connected with each other below the liquid level. A connector containing the same liquid and equal pressure on the liquid level has the same liquid level height.
(1) If the connector contains the same liquid, but the pressure on the liquid level is different, the pressure difference of the liquid level is equal to the pressure difference caused by the liquid level difference between the two containers of the connector.
(2) The pressure on the liquid level of the connector is equal, but there are different liquids on both sides that are not mixed with each other. The height of the two liquid levels from the dividing interface is inversely proportional to the liquid density.
The principle of connector is widely used in engineering. For example, various liquid level gauges (water level gauge, oil level gauge, etc.), mercury vacuum gauge, liquid column wind pressure gauge, differential pressure gauge, etc. are made by using the principle of connector.
Understanding the definition and working principle of connector will help us better understand and develop the connector market.
Basic performance of connector
Connector knowledge the basic performance of connectors can be divided into three categories: mechanical performance, electrical performance and environmental performance. Another important mechanical property is the mechanical life of the connector. Mechanical life is actually a durability index, which is called mechanical operation in national standard gb5095. It takes one insertion and one pull-out as a cycle, and takes whether the connector can normally complete its connection function (such as contact resistance value) after the specified plug-in cycle as the evaluation basis.
1. Mechanical properties as far as the connection function is concerned, the plugging force is an important mechanical property. The insertion force is divided into insertion force and pull-out force (pull-out force is also called separation force), and their requirements are different. There are provisions on the maximum insertion force and minimum separation force in relevant standards, which shows that the insertion force is small from the perspective of use (thus, the structure with low insertion force LIF and no insertion force ZIF), and if the separation force is too small, it will affect the reliability of the contact. The plug-in 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 ranges from a few milliohms to tens of milliohms.
② Insulation resistance is an index to measure the insulation performance between contacts of electrical connectors and between contacts and shell. 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 test voltage between connector contacts or between contacts and housing.
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 characteristic impedance, insertion loss, reflection coefficient Electrical indicators such as 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, high-speed signal connector, has emerged. Accordingly, in terms of electrical performance, in addition to characteristic impedance, some new electrical indicators have emerged, such as crosstalk, transmission delay and time delay (skew) et al.
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 connector is 200 ℃ (except for a few high-temperature special connectors), the minimum temperature is - 65 ℃. When the connector 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 specifications, the maximum temperature rise allowed by the connector under rated working current is clearly specified. ② the invasion of moisture resistance will affect the connection Grounding H insulation performance and corrosion of metal parts. The constant damp heat test condition is 90% ~ 95% relative humidity (up to 98% according to the product specification), temperature + 40 ± 20 ℃, and the test time shall be at least 96 hours according to the product regulations. The alternating damp heat test is more severe. ③ when the salt spray resistant connector works in the environment containing moisture and salt, the surface treatment layer of its metal structure and contact may produce electrochemical corrosion, affecting the physical and electrical properties of the connector. In order to evaluate the electrical connection Salt spray test is specified for the ability of the device to withstand this environment. It is to hang the connector in a temperature controlled test box and spray the specified concentration of sodium chloride solution with compressed air to form a salt mist atmosphere. The exposure time is specified by the product specification, which is at least 48 hours. ④ Vibration and shock resistance to vibration and shock is an important performance of electrical connectors. It is particularly important in special application environments, such as aviation and aerospace, railway and highway transportation. It is an important index to test the robustness of mechanical structure and electrical contact reliability of electrical connectors. There are clear provisions in the relevant test methods. The peak acceleration, duration and shock pulse waveform, as well as the time of interruption of electrical continuity, shall be specified in the impact test.
⑤ Other environmental properties according to the use requirements, other environmental properties of the electrical connector include tightness (air leakage, liquid pressure), liquid immersion (anti habitation ability to specific liquid), low air pressure, etc.