industry news
performance analysis and manufacturing technology of connectors
2019-09-21
the connector is also called a connector. between the blocked or isolated circuits in the circuit, a bridge of communication is established to allow current to flow, enabling the circuit to perform its intended function. domestically referred to as connectors and socket sockets, generally referred to as electrical connectors. that is, a device that connects two active devices to transmit current or signals.
connector performance
1. mechanical properties: insertion force is an important mechanical property in terms of connection function.
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. the maximum insertion force and minimum separation force are specified in the relevant standards, which indicates that the insertion force is small from the point of view of use (thereby having a low insertion force lif and a structure without zif insertion), and the separation force is too small. it will affect the reliability of the contact.
another important mechanical property is the mechanical life of the connector. mechanical life is actually an indicator of durability, which is called mechanical operation in gb5095. it is a cycle of one insertion and one extraction to judge whether the connector can normally complete its connection function (such as contact resistance value) after the specified insertion and removal cycle. the insertion force and mechanical life of the connector are related to the coating quality (sliding friction coefficient) of the contact structure (positive pressure) contact area and the dimensional accuracy (alignment) of the contact arrangement.
2. electrical performance: the main electrical properties of the connector include contact resistance, insulation resistance and electrical 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.
2 insulation resistance: a measure of the insulation properties between electrical connector contacts and between the contacts and the enclosure, in the order of hundreds of megaohms to several gigaohms.
3 electric strength: it is called withstand voltage and dielectric withstand voltage. it is the ability to characterize the rated test voltage between the connector contacts or between the contacts and the casing.
4 other electrical performance: 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, and is generally tested in the frequency range of 100mhz~10ghz.
for rf coaxial 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 connector, namely high-speed signal connector, has appeared. correspondingly, in addition to characteristic impedance, some new electrical indicators have appeared in electrical performance. such as crosstalk, delay, skew, etc.
3. environmental performance: common environmental properties include temperature resistance, moisture resistance, salt spray resistance, vibration and shock.
1 temperature resistance: the current maximum operating 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 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 connector at rated operating current is specified.
2 moisture resistance: intrusion of moisture can affect the insulation performance of the connector and corrode metal parts. the constant damp heat test conditions are relative humidity of 90%~95% (up to 98% according to product specifications), temperature 40± 20 °c, and test time is at least 96 hours according to product specifications. the alternating heat and humidity test is more stringent.
3 salt spray resistance: when the connector is operated in an environment containing moisture and salt, the metal structural parts and the surface treatment layer of the contact part may cause galvanic corrosion and affect 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 suspends the connector in a temperature-controlled test chamber and ejects 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: vibration and shock resistance are important properties of electrical connectors. they are especially important in special applications such as aerospace and aerospace, railway and road transportation. they are to verify the robustness and electrical contact of the mechanical structure of electrical connectors. an important indicator of 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 application requirements, other environmental properties of the electrical connector are also sealed (air leakage, liquid pressure), liquid impregnation (resistance to specific liquids), low air pressure, etc.
connector benefits
1. improve the production process: the connector simplifies the assembly process of electronic products. it also simplifies the mass production process;
2, easy to repair: if an electronic component fails, the replacement of the failed component can be quickly replaced when the connector is installed;
3, easy to upgrade: with the advancement of technology, when the connector is installed, the component can be updated, replacing the old one with a new, more complete component;
4. increase design flexibility: the use of connectors allows engineers to have greater flexibility in designing and integrating new products, as well as using components to form a system.
connector manufacturing process
connector process overview the production process of the connector components mainly includes: the manufacturing process of the parts and the assembly process of the products.
the connector component is mainly composed of contact parts, insulation parts and structural parts. the manufacturing process of the parts is mainly the processing technology of the three parts, such as machining, stamping, injection molding, die casting, surface coating, etc.
as the demand for the mating components continues to increase, the production quantities of the parts are large. therefore, the processing of the parts should be continuously improved with mechanization and automation, and more efficient special equipment is used to gradually realize the automatic production method of the plug components.
the contact parts are made by car or punching process. in the mass production, the car is mainly made of longitudinal automatic lathe, and the direction is to use multi-functional automatic machine tool to complete multiple processes on the equipment to avoid the second part. secondary processing, in order to improve the machining accuracy and production efficiency of parts. for small batch production, precision instrument lathe machining is available.
the characteristics of the punched contact parts are higher than that of the vehicle system, but the accuracy is slightly lower than that of the vehicle body. at present, the precision of the tooling and stamping equipment is continuously improved, so the precision of the punching contact parts is also greatly improved. the processes used are: making pins with a cold heading machine, making jacks with a multi-station press, and making reed contacts with a bending machine.
plastic insulation parts are mostly made of thermoplastics or thermosetting plastics according to their requirements. thermoplastic insulation parts have been closed and automated production, which is beneficial to improve work efficiency and reduce environmental pollution. thermoset plastics also use injection materials and processes. .
the structural parts are metal shell, plastic shell and other structural parts. the processing technology includes die casting, injection molding, cold extrusion, extrusion casting and machining. the use of metamorphic aluminum alloy cold extrusion shell process can achieve high strength and high precision. , high efficiency and other processing benefits.
common faults in connectors
there are three common types of fatal faults in terminal blocks:
poor contact
the metal conductor inside the terminal is the core part of the terminal that transfers the voltage, current or signal from the external wire or cable to the corresponding contact of the mating connector. therefore, the contact member must have an excellent structure, stable and reliable contact retention and good electrical conductivity. due to the unreasonable design of the contact structure, the wrong selection of materials, unstable mold, poor processing size, rough surface, unreasonable surface treatment process such as heat treatment and plating, improper assembly, poor storage and use, and improper operation, will be in the contact parts. contact and fitting 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 from the contacts and the contacts from the housing. therefore, the insulation must have excellent electrical properties, mechanical properties and process forming properties. in particular, with the high density and wide use of miniaturized terminals, the effective wall thickness of the insulator is getting thinner and thinner. this puts more stringent requirements on insulation materials, injection mold accuracy and molding processes. due to the presence of metal excesses on the surface or inside of the insulator, surface dust, flux and other pollution are damp, organic material precipitates and harmful gas adsorption film and surface water film fuse to form ionic conductive channels, moisture absorption, mildew, insulation material aging and other reasons, it will cause short circuit, leakage, breakdown, low insulation resistance and other insulation problems.
3. bad fixation
the insulator not only acts as an insulator, but also provides precise centering and protection for the extended contacts, as well as mounting and locking to the device. poor fixing, light contact affects reliable momentary power outage, and serious product disintegration. disintegration refers to the abnormal separation between the plug and the socket between the plug and the socket caused by the unreliable structure due to the material, design, process, etc., and the power transmission of the control system is caused by the disconnection of the terminal. the serious consequences of signal control interruption. due to unreliable design, incorrect material selection, improper selection of molding processes, poor quality of heat treatment, mold, assembly, welding, etc., the assembly is not in place, etc., which will result in poor fixing.
in addition, due to peeling, corrosion, bumping, plastic shell flashing, cracking, rough processing of the contact parts, deformation and other reasons, the appearance is poor, due to the poor positioning of the positioning and locking, the consistency of the processing quality is poor, the total separation force is too poor exchange caused by a large number of reasons is also a common disease, frequently-occurring disease. these kinds of faults can generally be found in the inspection and use process in time.
