What Is an Edge Connector?

Printed circuit boards (PCB) are devices that serve as a mechanical support and electrical connection point for various electronic components, used for nearly all modern electronic products. Printed circuit boards may feature a number of added peripherals and connectors that aid in the overall functionality of the system, each serving a unique role providing features that benefit the assembly. The edge connector is a common addition to a printed circuit board, serving as a component that mates with the PCB in order to provide an external electrical connection. As a component that is regularly found on PCBs for defining the power specifications of peripherals, it can be useful to understand their design and use.

Edge connectors are an embedded component, capable of mating with the edges of either a single-sided PCB or a double-sided PCB. In order to attach itself to a printed circuit board, the edge connector is designed to mate with a plastic box-shaped socket that features pins that protrude from the longer edges. As the male connector is provided by the edge of the PCB itself, the edge connector is fairly cheap, robust, and reliable.

Commonly used within personal computers, the edge connector serves for attaching either expansion cards or computer memory to the system bus of a PCB assembly. In general, edge connectors may be used to facilitate the connection of PCI, PCI Express, AGP hardware, hard disk drives, and other various components. Edge connectors may also be used alongside processors and microprocessors, the processor being mounted onto the edge connector rather than directly to the printed circuit board itself. Edge connectors have also been used for entertainment purposes such as for the construction of video game cartridges, those of which feature an edge connector that mates with a socket within the console.

To ensure an optimal connection and the transfer of signals, the contacts of the edge connector are constructed from metal that is plated with gold, copper, nickel, or silver. The coating is important to the overall functionality and health of the device, both increasing the conductivity of the contacts while mitigating rust and corrosion. To house the contacts, a plastic termination assembly is used. Contacts will also typically come in either one or two rows, and pins are separated by spaces ranging from 0.5 mm to 2.84 mm.

For the termination of the edge connector, a few methods may be used. With crimping, a contact wire barrel may be shaped around a conductor. Meanwhile, wire wrapping is used to wrap a wire around a terminal post, the wire either being stripped or unstripped. With the use of insulation displacement connectors, the insulation of connector cables can be sliced open so that the bare wires may establish a connection with the contact. With an IDC card edge connector, termination is achieved through displacement of the conductor insulation, thus removing the need to strip insulation. Alongside such methods, other means of termination may be achieved with the use of cage clamps, quick-connect tabs, screws, lugs, and more.