The gold finger of the flex PCB is a part of the flexible printed circuit board. It forms a gold conductive layer on the PCB through a special process for signal transmission and electrical connection in electronic devices.
What is a flex PCB gold finger?
Gold fingers refer to a row of golden conductive contacts on the edge of the printed circuit board. Because their shape and arrangement are similar to fingers, they are named "gold fingers". In flexible circuit boards, gold fingers are a key part of achieving stable and reliable electrical connections with other electronic devices or modules. These contacts are usually designed to be inserted into connectors for electrical connection. The surface finish of the gold finger is gold plating, usually hard gold plating, to provide excellent conductivity, wear resistance, and corrosion resistance. They are widely used in electronic devices that require high-frequency plug-in and high-reliability connections, such as computer motherboards, graphics cards, and some industrial control equipment.
Functions of gold fingers
Electrical connection: Provide reliable and stable electrical connection points to ensure smooth transmission of current and data signals.
Signal transmission optimization: Use materials with excellent conductive properties to reduce signal loss during transmission.
Wear and corrosion resistance: After special treatment, enhance its wear resistance and corrosion resistance and extend its service life.
Easy maintenance and upgrade: The design makes it easy and convenient to connect and disconnect the circuit board.
Types of flex PCB gold fingers
Based on shape, function and application, gold fingers can be divided into the following main types:
(1) Flush gold fingers (the most common gold fingers)
Features: neatly arranged, with the same length and width, usually arranged in a straight line on the edge of the flex PCB.
Purpose: suitable for standardized connectors such as graphics cards, memory sticks, etc.
Advantages: simple design, easy to produce, and strong adaptability.
(2) Segmented gold fingers
Features: The gold fingers are divided into multiple independent parts, and each segment of the contact can connect to different circuits.
Purpose: commonly used in multi-functional equipment, such as control boards for multi-channel signal transmission.
Advantages: improve the flexibility of circuit design.
(3) Wide and narrow alternating gold fingers
Features: The contact width is wide or narrow, which can meet different current and signal transmission requirements.
Purpose: It is mostly used for devices with high current requirements, such as power modules.
Advantages: It has strong adaptability and can support high-power transmission.
(4) Gold fingers of different lengths
Features: The gold fingers have different lengths to ensure that circuits in a specific order are connected first (such as grounding first).
Purpose: It is commonly used in power electronics and industrial automation control systems.
Advantages: It provides higher safety and prevents circuit short circuits or damage.
(5) Double-sided gold fingers
Features: The gold fingers are distributed on both sides of the PCB to increase the number of contacts.
Purpose: It is suitable for complex connection scenarios, such as high-density server interfaces.
Advantages: It provides more connection points in a limited space and improves performance.
Manufacturing process of gold fingers
The manufacturing process of gold fingers includes steps such as substrate treatment, chemical treatment, protective layer treatment and quality inspection. Among them, electroplating nickel gold and immersion gold are two common electroplating processes, which are used to improve the conductivity, oxidation resistance and wear resistance of gold fingers respectively.
In order to ensure reliable contact during the connection process, the ends of the gold fingers of some flexible circuit boards are designed to be slightly bent downward (usually invisible to the naked eye) to form a pre-crimped area. This can increase the contact pressure and ensure that there is enough pressure between the gold fingers and the connector pins when inserting the connector, thereby improving conductivity. It can also improve plug-in and pull-out performance, reduce the insertion force during initial contact, and make plug-in and pull-out smoother.
Application scenarios of gold fingers
Gold fingers are widely used in high-end electronic products such as smartphones, laptops, medical equipment, etc., for connecting motherboards and screens, flexible connections of internal circuits, and providing stable and reliable signal transmission.
By reasonably selecting and designing gold finger types, the needs of different electronic devices can be met, while improving the performance and reliability of the equipment. If more detailed technical analysis or cases are needed, please contact Flex Plus FPC.
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