Connector performance analysis and manufacturing process

Admin

Admin

Posts : 6693
Join date : 2019-05-10

Between the blocked or isolated circuits in the circuit, a bridge of communication is built, so that the current can flow and the circuit can realize the predetermined function. Domestically, they are also called connectors and sockets, and generally refer to <a href="https://www.klselectronic.com/products" rel="noopener noreferrer" target="_blank">electrical connectors</a>. That is, a device that connects two active devices to transmit current or signal. Connector performance 1. Mechanical performance: As far as connection function is concerned, insertion force is an important mechanical performance. Insertion and extraction force is divided into insertion force and extraction force (extraction force is also called separation force), the requirements of the two are different. There are provisions for maximum insertion force and minimum separation force in the relevant standards, which shows that from the perspective of use, the insertion force should be small (there are low insertion force LIF and no insertion force ZIF structure), and if the separation force is too small, It will affect the reliability of the contact. Another important mechanical property is the mechanical life of the <a href="https://www.klselectronic.com/products" rel="noopener noreferrer" target="_blank">connector</a>. Mechanical life is actually a durability indicator, which is called mechanical operation in the national standard GB5095. It takes one insertion and one extraction as a cycle, and whether the connector can normally complete its connection function (such as contact resistance value) after the specified insertion and removal cycle is used as the judgement basis. 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 (the sliding friction coefficient) and the dimensional accuracy of the contact arrangement (alignment). 2. Electrical performance: The main electrical performance of the connector includes contact resistance, insulation resistance and dielectric strength. ① 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. ②Insulation resistance: a measure of the insulation performance between the contacts of electrical connectors and between the contacts and the shell. Its magnitude ranges from hundreds of megohms to several thousand megohms. ③ Dielectric strength: also known as withstand voltage, dielectric withstand voltage, it is the ability to withstand the rated test voltage between the contact parts of the connector or between the contact part and the shell. ④Other electrical properties: Electromagnetic interference leakage attenuation is to evaluate the electromagnetic interference shielding effect of the connector, and electromagnetic interference leakage attenuation is to evaluate the electromagnetic interference shielding effect of the connector, and it is generally tested in the frequency range of 100MHz~10GHz. For radio frequency 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, a new type of connector, namely high-speed signal connector, has 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 lag (skew), etc. 3. Environmental performance: Common environmental performance includes resistance to temperature, humidity, salt spray, vibration and shock. ①Temperature resistance: The current maximum working temperature of the connector is 200℃ (except for a few high-temperature special connectors), and the lowest temperature is -65℃. When the connector is working, the current generates heat at the contact point and causes a temperature rise. Therefore, it is generally believed that the working 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 under the rated operating current is clearly specified. ② Humidity resistance: The intrusion of moisture will affect the insulation performance of the connector and rust metal parts. Constant humidity test conditions are relative humidity 90%~95% (according to product specifications, up to 98%), temperature +40 & #177; 20 ℃, test time according to product regulations, at least 96 hours. The alternating damp heat test is more stringent. ③Salt spray resistance: When the connector is working in an environment containing moisture and salt, the surface treatment layer of its metal structure and contact may produce galvanic corrosion, which affects the physical and electrical properties of the connector. In order to evaluate the ability of electrical connectors to withstand this environment, a salt spray test is specified. It hangs the connector in a temperature-controlled test box, sprays out a sodium chloride solution of a specified concentration with compressed air to form a salt spray atmosphere, and the exposure time is specified by the product specification, at least 48 hours. ④Vibration and shock: Vibration and shock resistance is an important performance of electrical connectors, especially in special application environments such as aviation and aerospace, railway and road transportation. It is to test the robustness and electrical contact of electrical connectors. An important indicator of reliability. There are clear regulations in the relevant test methods. In the shock test, the peak acceleration, duration and shock pulse waveform, as well as the interruption time of electrical continuity should be specified. ⑤Other environmental performance: According to the requirements of use, other environmental performances of the electrical connector include airtightness (air leakage, liquid pressure), liquid immersion (resistance to specific liquids), low air pressure, etc. Benefits of connectors 1. Improve the production process: connectors simplify the assembly process of electronic products. Also simplifies the mass production process; 2. Easy to repair: If an electronic component fails, the failed component can be quickly replaced when the connector is installed; 3. Easy to upgrade: As technology advances, components can be updated when connectors are installed, and new and more complete components can be used to replace the old ones; 4. Improve design flexibility: The use of connectors enables engineers to have greater flexibility when designing and integrating new products and when composing systems with components. Manufacturing process of connector Overview of connector technology The production technology of connector components mainly includes: parts manufacturing technology and product assembly technology. Connector components are mainly composed of contact parts, insulating parts and structural parts. The manufacturing process of the parts is mainly the processing technology of these three parts. Such as machining, stamping, injection molding, die casting, surface coating, etc. With the increasing demand for plug-in components, the production batches of parts are larger. Therefore, the processing of parts should continue to increase the degree of mechanization and automation, and more efficient special equipment should be used to gradually realize the automatic production of plug-in components. The contact parts are made by lathe or punching process. In mass production, the lathe is mainly made of slitting automatic lathes, and the direction is to use composite multi-function automatic machine tools to complete multiple processes on the equipment to avoid secondary parts. Sub-processing, in order to improve the accuracy of parts processing and production efficiency. For small batch production, precision instrument lathe processing can be used. The feature of stamping contact parts is higher than the car manufacturing efficiency, but its accuracy is slightly lower than that of the car body. At present, due to the continuous improvement of the accuracy of tooling and stamping equipment, the accuracy of the stamping contact parts has also been greatly improved. The processes used are: cold heading machines are used to make pins, multi-station punches are used to make sockets, and bending machines are used to make reed contacts. Plastic insulation parts are mostly made of thermoplastics according to their requirements for use, and thermosetting plastics can also be used. Thermoplastic insulation parts have realized closed automatic production, which is conducive to improving work efficiency and reducing environmental pollution. Thermosetting plastics also uses injection materials and processes. . Structural parts include metal shells, plastic shells and other structural parts. The processing techniques are die-casting, injection molding, cold extrusion, squeeze casting and machining. The cold-extrusion shell process of modified aluminum alloy can achieve high strength and good accuracy. , High efficiency and other processing benefits. Common faults of connectors There are three common fatal failure forms of terminal blocks: 1. Poor contact The metal conductor inside the terminal is the core part of the terminal. It transfers the voltage, current or signal from the external wire or cable to the corresponding contact of the connector. Therefore, the contact must have an excellent structure, stable and reliable contact retention and good electrical conductivity. Due to the unreasonable structure design of the contact parts, wrong material selection, unstable molds, out-of-poor processing dimensions, rough surface, unreasonable surface treatment processes such as heat treatment and electroplating, improper assembly, harsh storage and use environment, and improper operation and use, all contact parts Contact parts and matching parts cause poor contact. 2. Poor insulation The function of the insulator is to keep the contacts in the correct position, and to insulate the contacts and the contacts, and between the contacts and the housing. Therefore, the insulating parts must have excellent electrical properties, mechanical properties and process molding properties. Especially with the widespread use of high-density and miniaturized terminals, the effective wall thickness of the insulator becomes thinner and thinner. This puts more stringent requirements on insulating materials, injection mold accuracy and molding process. Due to the existence of metal excess on the surface or inside of the insulator, surface dust, flux and other pollution and moisture, organic material precipitates and harmful gas adsorption film merge with the surface water film to form ionic conductive channels, moisture absorption, mold growth, and aging of insulating materials. Will cause short circuit, leakage, breakdown, low insulation resistance and other poor insulation. 3. Poor fixation The insulator not only provides insulation, but also provides precise centering and protection for the protruding contacts. It also has the functions of installation and positioning and locking and fixing on the equipment. Poor fixation, the lighter will affect the reliable contact and cause instantaneous power failure, the more serious is the product disintegration. Disassembly refers to the abnormal separation between the plug and the socket, the pin and the socket caused by the unreliable structure of the terminal under the plug-in state due to material, design, process and other reasons, which will cause the power transmission of the control system and Serious consequences of signal control interruption. Due to unreliable design, wrong material selection, improper selection of molding process, poor quality of heat treatment, mold, assembly, welding and other processes, and improper assembly, etc., it will cause poor fixing. In addition, due to coating peeling, corrosion, bruising, plastic shell flashing, cracking, rough processing of contact parts, deformation, etc., the appearance is poor, due to the out-of-poor positioning and locking fit size, poor processing quality consistency, and total separation force Poor interchange caused by major causes is also a common and frequently-occurring disease. These types of faults can generally be found and eliminated in time during inspection and use.

Connector performance analysis and manufacturing process

1 Connector performance analysis and manufacturing process Mon Nov 23, 2020 8:10 am

Admin