A Brief Look at Edge Connectors
An Edge Connector is the section of a printed circuit board (PCB) that consists of traces leading to the edge of the board intended to plug into a compatible socket. Edge connectors are highly economical because they require only a single discrete female connector, as the male connector is formed out of the edge of the PCB. They are also known for being fairly robust and durable. Edge connectors are primarily used in computers for peripheral card expansion slots, such as PCI (Peripheral Component Interconnect), PCI Express, and AGP (Accelerated Graphics Port) cards.
In terms of design, edge connector sockets feature a plastic box open on one side, with pins on one or both sides of the longer edges, sprung such that they push into the middle of the open center. Connectors are frequently keyed to ensure the correct polarity, and may contain bumps or notches for polarity and to ensure that the wrong type of device is not inserted. The width of the socket is chosen to be compatible with the thickness of the connecting PCB. In most cases, mechanical force is required to insert the connectors into their sockets, though there are some alternatives which have zero insertion force. The opposing side of the socket is commonly an insulation-piercing connector clamped onto a ribbon cable. However, the other side may be soldered to a motherboard or daughtercard.
As stated, the advantages of edge connectors include that they are cost effective, simple to use, and tough. Other advantages include that they are a direct extension of the printed circuit board and can generally meet performance standards more reliably than their alternatives. Despite this, edge connectors also have certain drawbacks. For example, direct access to the PCB is not always ideal. The contact life of edge connectors is also short when compared to alternatives.
Edge connectors have a broad range of uses within electronics. They are commonly used in personal computers to connect expansion cards and computer memory to the system bus. IBM computers use edge connector sockets attached to ribbon cables to connect 5.25 inch floppy disk drives, though smaller drives use a pin connector instead. Video game cartridges also often take the form of a PCB with an edge connector; the socket is located within the console itself. The Nintendo Entertainment System, an early game system, was unique in that it utilized a zero insertion force connector. Instead of the user forcing the cartridge directly into the socket, the cartridge was first placed in a bay before being mechanically lowered into its position. Whatever you need edge connectors for, ensure you are getting them from a reputable source.
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