Basic Definition

The Card Edge Connector is a common type of electrical connector that provides an electrical and data connection between two circuit systems through direct contact between the “gold fingers” on the edge of the circuit board (PCB) and the flexible metal contacts inside the connector. This design eliminates the need for additional soldering or complex mechanical connections, and facilitates hardware expansion and maintenance.

Principle of operation

1. Contact Matching

– TheCard Edge Connector is designed with multiple flexible metal contacts (contact pads) on both sides of the connector slot.

– The gold fingers on the edge of the PCB are a copper conductive layer that is precisely gold plated to ensure excellent conductivity and wear resistance.

– When the gold fingers are inserted into the connector slot, the contacts are in direct contact with the gold fingers to establish an electrical connection.

2. Elastic pressure

– The metal contacts are designed with an elastic structure, when the gold finger is inserted, the contacts generate a certain pressure to ensure a stable mechanical and electrical connection, and at the same time to avoid poor contact due to vibration or movement.

3. Signal Transmission

– After insertion, signals are transmitted from the PCB gold finger through the connector contacts to another board or device connected to the connector.

– Optimized contact spacing and conductive materials reduce resistance and inductance, resulting in increased transfer rates and signal integrity.

Card Edge Connector Construction

1. Metal Slot (Contacts)

– Material: Contacts are typically made of gold-plated copper or silver-plated copper for high conductivity and oxidation resistance. Arrangement: Contacts are arranged in a spaced pattern.

– Arrangement: The contacts are spaced to match the gold finger design of the PCB. The spacing and number of contacts depends on the specific interface standard (e.g. PCIe, DIMM).

– Pressure Mechanism: The contacts are held in contact with the gold fingers by elastic pressure to ensure physical stability and electrical conductivity.

2. Card Edge Connector Interface

– The other end of the Card Edge Connector is connected to the motherboard or device circuit board by soldering or crimping.

– The interface types are diverse and can support high-speed transmission standards (such as PCIe 4.0, 5.0).

3. Card slot design

– The card slot is usually made of insulating material to provide physical support and alignment function to prevent misalignment or short circuit between the gold finger and contacts.

– The structure will be designed to guide the insertion direction to ensure proper connection of the device and to avoid reverse insertion to damage the component.

Card Edge Connector works in conjunction with the PCB

1. Gold Finger Design

– The gold fingers on the PCB are made of copper foil with gold plating to improve conductivity and corrosion resistance.

– Each gold finger corresponds to a signal line or power line and is responsible for the transmission of a specific signal or power.

2. Mechanical Matching

– The thickness of the PCB, the length and width of the gold fingers, and the contact spacing need to be perfectly matched to the connector’s specifications to ensure smooth plugging and unplugging.

– Most Card Edge Connector designs are designed to support multiple insertions and removals and the insertion and removal forces are optimized to not damage the PCB or connector.

3. Electrical Connections

– The Card Edge Connector’s connection to the PCB provides low-impedance and high-frequency signal transmission through high-quality contacts and precise mechanical mating.

–Card Edge Connectors in high-speed interfaces such as PCIe are subjected to rigorous signal integrity testing to ensure low noise and high signal quality.

Benefits and Features

1. Stable electrical connection

– Contact pressure and gold plating of the gold fingers ensure a reliable connection over long periods of time.

2. Easy to insert and remove

– The card slot design simplifies installation and replacement and supports hot swapping.

3. High Expandability

– Allows multiple PCBs to be connected to the same motherboard, enhancing the expandability of the hardware system.

Summary

The Card Edge Connector provides a reliable and scalable electrical connection through its simple and efficient design. Its basic mode of operation relies on precision contact between metal contacts and gold fingers, enabling high-speed transmission and long-term stability through optimized mechanics and high-quality materials. The synergy between this connector and the PCB makes it an indispensable key component in the field of computer hardware.

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