Connector, that is, connector. It is also called connector, plug and socket in China. Generally refers to the electrical connector. That is, a device that connects two active devices to transmit current or signal.
Connector is a kind of component that our electronic engineers and technicians often contact. Its function is simple: to build a communication bridge between blocked parts or isolated circuits in the circuit, so as to make the current flow and make the circuit realize the predetermined function. Connector is an indispensable part in electronic equipment. If you look along the current path, you will always find one or more connectors. The forms and structures of connectors are ever-changing. There are various types of connectors according to different application objects, frequencies, power and application environments. For example, the connectors used for lighting on the court are very different from those used for hard disk drives and rocket ignition. But no matter what kind of connector, it is necessary to ensure the smooth, continuous and reliable flow of current. Generally speaking, the connection of connectors is not limited to current. Today, with the rapid development of photoelectric technology, the carrier of signal transmission in optical fiber system is light, and glass and plastic replace the wires in ordinary circuits. However, connectors are also used for optical signal paths and have the same function as circuit connectors. Because we only care about circuit connectors, this course will focus on circuit connectors and their applications closely related to Molex products.
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2 Why use connectors?
Imagine what it would be like without connectors. At this point, the circuit should be permanently connected by a continuous conductor. For example, if an electronic device is to be connected to a power supply, both ends of the connecting wire must be fixedly connected to the electronic device and the power supply by some method (such as welding). In this way, both for production and use, have brought a lot of inconvenience. Take the car battery as an example. Assuming that the battery cable is fixedly welded to the battery, the workload of installing the battery in the automobile factory will increase, and the production time and cost will increase. When the battery is damaged and needs to be replaced, it is necessary to take the car to the maintenance station, remove the old one by welding, and then weld a new one, which will consume more manpower. With the connector, you can avoid a lot of trouble. Just buy a new battery from the store, disconnect the connector, take out the old battery, install a new battery and reconnect the connector. This simple example illustrates the benefits of connectors. It makes the design and production process more convenient and flexible, and reduces the production and maintenance costs.
Advantages of connectors:
1, improve the production process
Connectors simplify the assembly process of electronic products. But also simplifies the mass production process;
2, easy to maintain
If the electronic component fails, the faulty component can be quickly replaced when installing the connector;
3, easy to upgrade
With the development of technology, components can be updated when connectors are installed, and old components can be replaced by new and more perfect components;
4. Improve the flexibility of design.
The use of connectors gives engineers more flexibility in designing and integrating new products and composing systems with components.
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3 Basic performance of connectors
The basic performance of connectors can be divided into three categories: mechanical performance, electrical performance and environmental performance. Another important mechanical characteristic is the mechanical life of the connector. Mechanical life is actually a durability index, which is called mechanical operation in GB5095. It takes one insertion and one pull-out as a cycle, and judges whether the connector can normally complete its connection function (such as contact resistance value) after the specified insertion cycle.
1. Mechanical properties In terms of connection function, insertion force is an important mechanical property. Insertion force is divided into insertion force and extraction force (extraction force is also called separation force), and their requirements are different. The maximum insertion force and minimum separation force are specified in the relevant standards, which shows that from the point of view of use, the insertion force is small (thus there is a 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 contact. Plug-in force and mechanical life of connectors are related to contact structure (positive pressure), coating quality (sliding friction coefficient) and contact dimensional accuracy (alignment).
2. Electrical properties The main electrical properties of connectors 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 several tens of milliohms.
(2) Insulation resistance is an index to measure the insulation performance between contacts and between contacts and shell of electrical connector, and its order of magnitude ranges from several hundred megohms to several gigaohms.
(3) Electrical strength, or withstand voltage and dielectric withstand voltage, is the ability to withstand rated test voltage between connectors or between connectors and housings.
④ Other electrical properties.
Electromagnetic interference leakage attenuation is to evaluate the electromagnetic interference shielding effect of connectors, and it is generally tested in the frequency range of 100MHz~ 10GHz.
For RF 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, appears. Correspondingly, in terms of electrical performance, besides characteristic impedance, some new electrical indicators have appeared, such as crosstalk, transmission delay, skew and so on.
3. Environmental properties Common environmental properties include temperature resistance, humidity resistance, salt spray resistance, vibration and impact.
① Temperature resistance At present, the highest working temperature of connectors is 200℃ (except for a few high-temperature special connectors), and the lowest temperature is -65℃. When the connector works, the current generates heat at the contact point, which leads to an increase in temperature. Therefore, it is generally believed that the working temperature should be equal to the sum of the ambient temperature and the contact temperature rise. In some specifications, the maximum allowable temperature rise of connectors under rated working current is clearly defined. (2) The invasion of moisture will affect the insulation performance of connection H and corrode metal parts. The conditions of constant moist heat test are relative humidity of 90%~95% (up to 98% according to the product specification), temperature of+40 20℃ and test time of at least 96 hours according to the product specification. The alternating damp-heat test is more severe. (3) When the salt spray resistant connector works in an environment containing water and salt, the metal structure and the surface treatment layer of the contact may produce electrochemical corrosion, thus affecting the physical and electrical properties of the connector. In order to evaluate the ability of electrical connectors to withstand this environment, salt spray test is stipulated. It is to hang the connector in a temperature-controlled test box, and spray a sodium chloride solution with a specified concentration with compressed air to form a salt spray environment, and its exposure time is at least 48 hours specified in the product manual. ④ Anti-vibration and impact is an important performance of electrical connectors, especially in special application environments such as aerospace, railway and road transportation. It is an important index to test the firmness of mechanical structure and the reliability of electrical contact. It is clearly defined in the relevant test methods. The peak acceleration, duration, impact pulse waveform and interruption time of electrical continuity should be specified in the impact test.
⑤ Other environmental characteristics According to the use requirements, other environmental characteristics of the electrical connector include sealability (air leakage, liquid pressure), liquid immersion (resistance to specific liquid), low air pressure, etc.
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4 categories and definitions of connectors
With the increasing diversification of connector structures and the emergence of new structures and application fields, it is difficult to adapt to trying to solve the classification and naming problems with fixed models. Nevertheless, some basic classifications are still valid.
1. Interconnection level
According to the functions of internal and external connections of electronic equipment, interconnection can be divided into five levels.
① Internal connection of chip package
② Connection between IC package pin and PCB. Typical connector IC socket.
③ Connection between printed circuit and conductor or printed board. A typical connector is a printed circuit connector.
(4) Connection between bottom plates. A typical connector is a cabinet connector.
⑤ Connection between devices. A typical product is a circular connector.
There is some overlap between the third and fourth levels. Among the five levels of connectors, the third and fifth levels are the highest in market value, and the third level is the fastest growing at present.
2. The level of connector specifications.
According to the classification of the International Electrotechnical Commission (IEC), connectors belong to electromechanical components for electronic equipment, and their specifications are as follows:
Family example: connectors
Subfamily Example: Circular Connector
Type: YB type circular connector.
Example of style: YB3470
Specification (variant)
3. Definition of connector in China.
In China's industrial management, connectors, switches, keyboards, etc. They are collectively referred to as electrical plug-in components, while electrical plug-in components and relays are collectively referred to as electromechanical components.
4. Product category of connector.
Although the classification of connector product types is somewhat confusing, technically speaking, there are only two basic ways to classify connector product types: ① according to the external structure: circular and rectangular (cross section), and ② according to the working frequency: low frequency and high frequency (bounded by 3MHz).
According to the above classification, coaxial connectors are round, and printed circuit connectors are rectangular (historically, printed circuit connectors are indeed separated from rectangular connectors and belong to their own category), but now the popular rectangular connectors are trapezoidal in cross-section, almost rectangular. The division of low frequency and high frequency by 3MHz is basically consistent with the frequency division of radio waves.
As for others, they can be divided into many different types according to their uses, installation methods, special structures and special properties. , and they often appear in publications and promotional materials of manufacturers, but generally only to highlight a certain characteristic and use, the basic classification still does not exceed the above-mentioned division principle.
Considering the technical development and actual situation of connectors, according to their universality and related technical standards, connectors can be divided into the following categories (subclasses): ① low-frequency circular connectors; ② Rectangular connector; ③ Printed circuit connector; ④ RF connector; ⑤ Optical fiber connector.
5. Name of connector model.
The model naming of connectors is the basis for customers to purchase and manufacturers to organize production. In the connector industry at home and abroad, there are two ways to name the product model: one is to use letters and numbers to reflect the main structural characteristics of the product in the model naming. The advantage of this method is that it is easy to identify, but the arrangement is too long and complicated. With the miniaturization of connectors, it brings many difficulties to printing. At present, this method is still popular in China, and it is stipulated in some industry standards and even national standards, such as SJ2298-83 (printed circuit connector), SJ2297-83 (rectangular connector), SJ2459-84 (ribbon cable connector) and GB9538-88 (ribbon cable connector). Due to the increasing diversity of connector structures, it is increasingly difficult to cover a certain type of connector with a naming rule in practice. Another idea is to combine Arabic numerals. The advantage of this method is that it is simple and convenient for computer management and logo printing of small products. At present, the main connector manufacturers in the world adopt this method. It can be expected that the naming method developed by manufacturers to reflect their own characteristics will gradually replace the method of unifying some naming rules in the whole industry under the planned economy system.
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Overview of connector market development
With the rapid growth of consumer electronics, automotive electronics and communication terminal markets, and the continuous transfer of global connector production capacity to Asia and China, Asia has become the most potential place in the connector market, and China will become the fastest growing and largest connector market in the world. It is predicted that the growth rate of connector market in China will continue to exceed the global average in the future. In the next five years, the average annual growth rate of connector market in China will reach 15%, and by 20 10, the connector market capacity in China will reach 25.7 billion yuan.
The main areas supported by electrical connectors are transportation, communication, network, IT, medical treatment, household appliances and so on. The rapid development of product technology level and the rapid growth of supporting market have strongly promoted the development of connector technology. So far, the connector has developed into a series of professional products with complete product categories, rich varieties and specifications, diverse structural types, subdivided professional direction, obvious industry characteristics and standardized standard system.
Generally speaking, the development of connector technology presents the following characteristics: high-speed and digitalization of signal transmission, integration of various signal transmission, miniaturization of product volume, reduction of product cost, surface-to-surface contact termination mode, modular combination, convenient plugging and unplugging, etc. The above technology represents the development direction of connector technology, but it should be noted that the above technology is not necessary for all connectors, and the requirements for connectors in different support fields and different use environments are completely different.
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6 development direction of connectors
The development of connectors should be miniaturization, high density, high speed transmission and high frequency. Miniaturization means that the distance between connector centers is smaller, and high density means more cores. The total number of effective contacts of high-density PCB (printed circuit board) connectors is 600 cores, and the maximum number of special devices is 5000 cores. High-speed transmission means that modern computer, information technology and network technology require that the time scale rate of signal transmission reaches MHz band and the pulse time reaches sub-millisecond level, so high-speed transmission connectors are needed. In order to adapt to the development of millimeter wave technology, RF coaxial connectors have entered the millimeter wave working frequency band. [ 1]
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7 well-known connector manufacturers at home and abroad
Glossary of common terms for AVIC Optoelectronics, Aerospace Electric Appliances, Sichuan Huafeng, Foxconn Technology, Tyco Electronics, Moshi, Amphenol, FCI, JAE and connectors.
1. connector: a detachable component (except adapter) usually attached to a cable or equipment, used for electrical connection of transmission line systems.
2. RF connector: This is a connector for RF range.
3. Video: Radio waves with frequency range of 3HZ∽30MHZ.
4. Radio frequency: radio waves with a frequency range of 3 kHz∽3000 GHz.
5. High frequency: radio waves with frequency range of 3MHZ∽30MHZ.
6. Coaxial: The inner conductor is supported by dielectric, so the minimum internal reflection coefficient can be obtained in the frequency range used for measurement.
7. Triaxial transmission line: a transmission line consisting of three coaxial and insulated conductors.
8. Grade: the mechanical and electrical accuracy level of the connector, especially the specified reflection coefficient.
9. Universal connector (Class 2): A connector that has the maximum allowable dimensional deviation (tolerance) when manufactured, but still ensures the minimum specified performance and compatibility.
Note: The requirement of reflection coefficient can be specified or not.
10. High-performance connector (Class 1): A connector that specifies the limit value of reflection coefficient according to frequency change. Generally, the specified dimensional tolerance will not be stricter than that of the corresponding Class 2 connector, but when it is necessary to ensure that the connector meets the requirements of reflection coefficient, it is the manufacturer's responsibility to choose a stricter tolerance.
1 1. standard test connector (class 0): a special type of connector, which is precisely manufactured and used to measure the reflection coefficient of 1 and class 2 connectors, and the error caused by the measurement results can be ignored.
Note: Standard test connectors are usually part of different types of adapters, and adapters are connected with precision connectors to form a part of test equipment.
12. seal
12. 1 sealed connector: a connector that can meet the specified gas, moisture or liquid sealing requirements.
12.2 isolation seal: a seal that prevents gas, moisture or liquid from entering the connector housing in the axial direction.
12.3 panel seal: prevent gas, moisture or liquid from entering the seal between the fixed or adapter housing and the panel through the mounting hole.
Note: Seals are usually provided as stand-alone products.
12.4 plug-in surface seal: a seal that prevents gas, moisture or liquid from entering the interface of a pair of plug-in connectors.
12.5 gas seal: a seal that meets the requirements of test Qk specified in IEC60068-2- 17 "basic environmental test specification part 2: test-test q: sealing".
Basic structural composition of connector
The basic structural components of the connector are ① contact components; ② Insulator; ③ Shell (depending on the variety); 4 accessories.
The 1. contact is the core component of the connector to complete the electrical connection function. Usually, a contact pair consists of a male contact and a female contact, and the electrical connection is completed through the insertion of the female contact and the male contact.
The male contact is a rigid part, and its shape is cylindrical (round pin), square column (square pin) or flat (insert). Male contacts are usually made of brass and phosphor bronze.
The female contact, namely the jack, is the key part of the contact pair. It relies on the elastic deformation of the elastic structure when inserting the pin to generate elastic force and form close contact with the male contact to complete the connection. There are many kinds of jack structures, such as cylindrical (split slot, necking), tuning fork, cantilever (longitudinal slot), folding (longitudinal slot, 9-shaped), box (square jack), hyperboloid wire spring jack, etc.
2. Insulators Insulators are also often called bases or inserts. Its function is to arrange the contacts according to the required position and spacing, and ensure the insulation performance between contacts and between contacts and shell. Good insulation resistance, withstand voltage and machinability are the basic requirements for selecting insulation materials for insulators.
3. The shell, also known as the shell, is the outer cover of the connector, which provides mechanical protection for the built-in insulating mounting plate and pin, and provides alignment when the plug and socket are inserted, thus fixing the connector on the equipment.
4. Accessories are divided into structural accessories and installation accessories. Structural accessories, such as circlip, locating key, locating pin, guide pin, coupling ring, cable clamp, sealing ring, gasket, etc. Install accessories, such as screws, nuts, screws, spring rings, etc. Most accessories have standard parts and common parts.
Brief introduction of connector structure principle
The basic structural components of the connector are ① contact components; ② Insulator; ③ Shell (depending on the variety); 4 accessories.
Contact is the core component of the connector to complete the electrical connection function. Usually, a contact pair consists of a male contact and a female contact, and the electrical connection is completed through the insertion of the female contact and the male contact.
The male contact is a rigid part, and its shape is cylindrical (round pin), square column (square pin) or flat (insert). Male contacts are usually made of brass and phosphor bronze. ]
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2. Insulators Insulators are also often called bases or inserts. Its function is to arrange the contacts according to the required position and spacing, and ensure the insulation performance between contacts and between contacts and shell. Good insulation resistance, withstand voltage and machinability are the basic requirements for selecting insulation materials for insulators.
3. The shell, also known as the shell, is the outer cover of the connector, which provides mechanical protection for the built-in insulating mounting plate and pin, and provides alignment when the plug and socket are inserted, thus fixing the connector on the equipment.
4. Accessories are divided into structural accessories and installation accessories. Structural accessories, such as circlip, locating key, locating pin, guide pin, coupling ring, cable clamp, sealing ring, gasket, etc. Install accessories, such as screws, nuts, screws, spring rings, etc. Most accessories have standard parts and common parts. Connector, connector technology, electronic connector, connecting wire, connector, terminal, cable harness, switch, wire and cable, optical fiber connector, computer connector, connector, cable, card holder, harness, jst, HDMI, USB, molex, AMP, terminal, terminal, FPC, Shenzhen, switch, pin, RF coaxial connector, FFC.
Basic performance of connector
The basic performance of connectors can be divided into three categories: mechanical performance, electrical performance and environmental performance.
1. Mechanical properties In terms of connection function, insertion force is an important mechanical property. Insertion force is divided into insertion force and extraction force (extraction force is also called separation force), and their requirements are different. The maximum insertion force and minimum separation force are specified in the relevant standards, which shows that from the point of view of use, the insertion force is small (thus there is a 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 contact.
Another important mechanical characteristic is the mechanical life of the connector. Mechanical life is actually a durability index, which is called mechanical operation in GB5095. It takes one insertion and one pull-out as a cycle, and judges whether the connector can normally complete its connection function (such as contact resistance value) after the specified insertion cycle.
Plug-in force and mechanical life of connectors are related to contact structure (positive pressure), coating quality (sliding friction coefficient) and contact dimensional accuracy (alignment).
2. Electrical performance
Field application engineer, market application engineer
I just collected and synthesized the working definition.
1. Collect and analyze customer status information (production and R&D)-and feed back the corresponding information to sales &; R&D, making product specifications internally according to customer standards;
2. Assist sales staff to introduce new products (including imported products) to customers. If sales intend to send samples, it is necessary to inform FAE of relevant information in advance;
3. Assist and define the quality assurance of product ORT verification and analysis;
4. Pay attention to and collect market information, comprehensively analyze it and feed it back to the management and R&D department of the company; Sales to do related research and development trends and product promotion evaluation;
5. Support CQS to solve technical problems related to products raised by customers;
6. Complete the analysis of CQS&; Competitor products collected by the sales department that need internal reference (samples and complete reports should be kept);
Thank you for your assistance. Thank you.