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    2021-10-21 17:39:01
    Everything You Need to Know about Connectors

    Topics covered in this article:

    What is an electrical connector?

    What are the types of connectors?

    What is the basic performance of a connector?

    What is the basic structure of a connector?

    What are the characteristics of a connector?


    What is an electrical connector?

    An electrical connector is a device that connects two active devices and transmits current or signals. The role of the connector: to build a bridge of communication between the blocked or isolated circuits in the circuit, so that the current can flow, and the circuit can realize the predetermined function. The connector is an indispensable part of electronic equipment. You'll always find one or more connectors if you look along the line of current flow.

    The shapes and topologies of electrical connectors are constantly changing. Electrical connectors come in a variety of shapes and sizes, with varying application objects, frequencies, power, and application settings. For example, the connectors for lighting on the court and the connectors for hard drives, and the connectors for igniting rockets are quite different. But no matter what kind of connector, it is necessary to ensure that the current flows smoothly, continuously, and reliably. What the connector is attached to is not restricted to current in general. The carrier of the signal in an optical fiber system is light in today's rapid growth of optoelectronic technology. In a traditional circuit, wires are replaced by glass and plastic. But connectors are also used in optical signal paths, and their functions are the same as circuit connectors.

    all kinds of connectors.jpg

    all kinds of connectors

    The fighter aircraft manufacturing technology inspired the creation of the connection. The aircraft in the combat must be refueled and repaired on the ground, and the amount of time spent on the ground determines whether the war is won or lost. Therefore, during World War II, the US military authorities were determined to reduce ground maintenance time and increase combat time due to fighter jets.

    They first united various control instruments and parts, and then connected them into a whole system by electrical connectors. Disassemble the defective unit and replace it with a new one during repairs, and the aircraft will be able to take to the air right away. After the war, AT-T Bell Labs successfully developed the Bell telephone system, and then the rise of the computer, communications, and other industries gave more opportunities for the development of connectors derived from stand-alone technology, and the market expanded rapidly.

    What are the types of connectors?

    As the structure of the connector is becoming increasingly diversified, new structures and application fields are constantly appearing, trying to solve the classification and naming problems with a fixed model has become difficult.

    1. The nature of use

    External connector (for external enclosure), internal connector (for internal enclosure).

    2. The level of the connector

    ● Level 1. Device to packaging: Refers to the connection between the IC CHIP and the pin.

    Device to packaging connector.jpg

    Device to packaging connector

    ● Level 2. Component lead to circuitry: Refers to the connection between component and PC board.

    component to pcb.jpg

    component to PCB

    ● Level 3. Board To Board: Refers to the interconnection between the PC board and the PC board.

    Board To Board connector.jpg

    Board To Board connector

    ● Level 4. Sub-assembly to Sub-assembly



    ● Level 5. Subassembly to I/O port



    ● Level 6. System to system



    3. The processing method

    Crimp type, I.D.CType (also known as piercing type), solder type, Z.I.F Type.

    4. The method of use

    Wire-to-board connectors, board-to-board connector wires, wire-to-wire connectors, sockets, input and output connectors.

    5. The form

    PCB board connectors, flat cable connectors, coaxial cable connectors, integrated connectors, pinch connectors, round connectors, angle connectors, and connectors for printed wiring boards are all examples of connectors for printed wiring boards.

    6. The structure

    Moisture-resistant and waterproof connectors, environment-resistant connectors, air-tight connectors, fire-resistant connectors, and water-resistant connectors are all examples of connectors.

    7. The working frequency

    Low frequency and high frequency (with 3MHz as the boundary).

    8. Connectors can be classified into the following groups based on their adaptability and technical standards:

    ① Low-frequency circular connector;

    ② Rectangular connector;

    ③ Printed circuit connector;

    ④ RF connector;

    ⑤ Optical fiber connector.

    What is the basic performance of a connector?

    The basic performance of electrical connectors can be divided into three categories: mechanical performance, electrical performance and environmental performance.

    1. Mechanical behavior

    As far as the connection function is concerned, the insertion and extraction force is an important mechanical property. The force of insertion and extraction is separated into two categories: insertion force and extraction force. The demands of the two are distinct. The applicable criteria include provisions for maximum insertion force and minimum separation force, indicating that the insertion force should be small from the standpoint of use (there are low insertion force LIF and no insertion force ZIF structure). The contact's reliability will be harmed if the separation force is too minimal. The plug-in force and mechanical life of the connector are related to the contact structure (positive pressure), the coating quality (sliding friction coefficient) of the contact part, and the dimensional accuracy of the contact arrangement (alignment).

    2. Electrical performance

    Contact resistance, insulation resistance, and dielectric strength are the key electrical attributes of the connector.

    ① Contact resistance should be low and stable in electrical connectors with high-quality contact resistance. The connector's contact resistance varies from a few milliohms to tens of milliohms.

    ② Insulation resistance is a measure of the insulation performance between electrical connector contacts and between the contacts and the shell, and its magnitude ranges from hundreds of megohms to thousands of megohms.

    ③ Dielectric strength, or withstand voltage, dielectric withstand voltage, is the ability to withstand the rated test voltage between the connector contacts or between the contacts and the shell.

    ④ Other electrical properties.

    The electromagnetic interference leakage attenuation test is used to determine the connector's electromagnetic interference shielding effect, and it is typically performed in the frequency range of 100MHz to 10GHz.

    Electrical indications for radiofrequency coaxial connectors include characteristic impedance, insertion loss, reflection coefficient, and voltage standing wave ratio (VSWR). Due to the advancement of digital technology, a new form of a connector, known as a high-speed signal connector, has emerged to link and transmit high-speed digital pulse signals. As a result, in addition to the characteristic impedance, several new electrical indicators, such as crosstalk, transmission delay, skew, and so on, have developed in terms of electrical performance.

    3. Environmental performance

    Common environmental properties include temperature resistance, humidity resistance, salt spray resistance, vibration and shock resistance, etc.

    ①Temperature resistance. Connectors now have a maximum working temperature of 200°C (with the exception of a few high-temperature special connectors) and a minimum temperature of -65°C. When the connector is in use, the current produces heat at the contact site, causing the temperature to rise. As a result, it is commonly assumed that the working temperature should be the total of the ambient temperature plus the temperature rise of the contact point. The maximum temperature rise allowed by the connector under the rated operational current is clearly mentioned in some specifications.

    ②Humidity resistance. The intrusion of moisture will affect the insulation performance of the connection h and rust metal parts. Constant humidity test conditions are relative humidity 90%-95% (according to product specifications, up to 98%), temperature +40±20℃, the test time is as per product specifications, 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. A salt spray test is required to assess the ability of electrical connectors to tolerate this environment. It creates a salt spray atmosphere by hanging the connector in a temperature-controlled test box and spraying it with compressed air with a specific concentration of sodium chloride solution. The product specification specifies that the exposure time is at least 48 hours.

    ④Vibration and shock. Electrical connectors' vibration and shock resistance are key features. It is particularly important in special application environments such as aviation and aerospace, railway, and road transportation. It is an important indicator for testing the robustness of the electrical connector’s mechanical structure and electrical contact 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. Other environmental performances of the electrical connector, depending on the requirements of use, include sealing, liquid immersion, low air pressure, and so on.

    What is the basic structure of a connector?

    The basic structural parts of the connector are ① contact; ② insulator; ③ shell (depending on the type); ④ accessories.

    1. Contact

    It is the central component of the connector that allows the electrical connection to be completed. Generally, a contact pair is composed of a male contact piece and a female contact piece, and the electrical connection is completed by the insertion of the female and male contact pieces.

    The male contact is a rigid part, and its shape is cylindrical (round pin), square cylinder (square pin), or flat (insert piece). The male contact is generally made of brass or phosphor bronze.

    The female contact piece, the socket, is the key part of the contact pair. When inserted into the pin, the elastic structure is elastically bent, generating elastic force and forming close contact with the male contact piece to complete the connection. Jack structures include cylindrical (split, necking), tuning fork, cantilever type (longitudinal slot), folding type (longitudinal slot, 9-shaped), box-shaped (square jack), and hyperboloid wire spring jack, among others.

    2. Insulator

    The insulator is also often called the base or the insert. Its purpose is to place and space the contacts as needed, as well as to ensure good insulation between the contacts and between the contacts and the housing. The primary requirements for selecting insulating materials to be processed into insulators are good insulation resistance, withstand voltage performance and ease of processing.

    3. Shell

    The shell is the connector's exterior cover. It protects the built-in insulating mounting plate and pins from mechanical damage, aligns the plug and socket after mating, and finally secures the connector to the device.

    4. Accessories

    Structural and installation accessories are the two types of accessories. Clamp rings, positioning keys, positioning pins, guiding pins, connecting rings, cable clamps, sealing rings, gaskets, and other structural accessories Screws, nuts, screws, spring rings, and other accessories should be installed. The majority of the accessories are made up of regular and popular parts.

    What are the characteristics of a connector?

    1. Either the male contact or the female contact is flexible. The mutual connection of the contacts can be used to ensure the circuit connection.

    2. The terminal part of the contact has a wiring structure that is easy to implement wires or printed wiring boards. It is for the implementation of welding, encapsulation, holding, through-hole welding, and other structures.

    3. The insulator is used to maintain the voltage insulation resistance between the contacts, and the contact is secured at the correct position of the insulator.

    4. It has a coupling structure, which is convenient for the insertion or removal of the contact, and it does not change its position even after vibration or impact.

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