An edge connector is the portion of a printed circuit board

Printed circuit board

A printed circuit board, or PCB, is used to mechanically support and electrically connect electronic components using conductive pathways, tracks or signal traces etched from copper sheets laminated onto a non-conductive substrate. It is also referred to as printed wiring board or etched wiring...

 (PCB) consisting of traces leading to the edge of the board that are intended to plug into a matching socket

Jack (connector)

In electronics and electrical assemblies, the term jack commonly refers to a surface-mounted connector, often, but not always, with the female electrical contact or socket, and is the "more fixed" connector of a connector pair...

. The edge connector is a money-saving device because it only requires a single discrete female connector (the male connector is formed out of the edge of the PCB), and they also tend to be fairly robust and durable. They are commonly used in computers for expansion slots

Expansion slots

Expansion slots are specific slots on a PC motherboard that facilitate the placement of expansion cards.All such expansion slots are colour coded, and are built in such a way that only a specific type of card or device can interface with/ be inserted into the device.- Types :Common types of...

 for peripheral cards, such as PCI

Peripheral Component Interconnect

Conventional PCI is a computer bus for attaching hardware devices in a computer...

, PCI Express

PCI Express

PCI Express , officially abbreviated as PCIe, is a computer expansion card standard designed to replace the older PCI, PCI-X, and AGP bus standards...

, and AGP cards.

Socket design

Edge connector sockets consist of a plastic "box" open on one side, with pins on one or both side(s) of the longer edges, sprung to push into the middle of the open center. Connectors are often keyed to ensure the correct polarity

Electrical polarity

Electrical polarity is present in every electrical circuit. Electrons flow from the negative pole to the positive pole. In a direct current circuit, one pole is always negative, the other pole is always positive and the electrons flow in one direction only...

, and may contain bumps or notches both for polarity and to ensure that the wrong type of device is not inserted. The socket's width is chosen to fit to the thickness of the connecting PCB.

The opposite side of the socket is often an insulation-piercing connector which is clamped onto a ribbon cable

Ribbon cable

A ribbon cable is a cable with many conducting wires running parallel to each other on the same flat plane. As a result the cable is wide and flat. Its name comes from the resemblance of the cable to a piece of ribbon.Ribbon cables are usually seen for internal peripherals in computers, such as...

. Alternatively, the other side may be solder

Solder

Solder is a fusible metal alloy used to join together metal workpieces and having a melting point below that of the workpiece.Soft solder is what is most often thought of when solder or soldering are mentioned and it typically has a melting range of . It is commonly used in electronics and...

ed to a motherboard

Motherboard

In personal computers, a motherboard is the central printed circuit board in many modern computers and holds many of the crucial components of the system, providing connectors for other peripherals. The motherboard is sometimes alternatively known as the mainboard, system board, or, on Apple...

 or daughtercard.

Uses

Edge connectors are commonly used in personal computer

Personal computer

A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator...

s for connecting expansion card

Expansion card

The expansion card in computing is a printed circuit board that can be inserted into an expansion slot of a computer motherboard or backplane to add functionality to a computer system via the expansion bus.One edge of the expansion card holds the contacts that fit exactly into the slot...

s and computer memory

Computer memory

In computing, memory refers to the physical devices used to store programs or data on a temporary or permanent basis for use in a computer or other digital electronic device. The term primary memory is used for the information in physical systems which are fast In computing, memory refers to the...

 to the system bus

System bus

A system bus is a single computer bus that connects the major components of a computer system. The technique was developed to reduce costs and improve modularity....

. Example expansion peripheral technologies which use edge connectors include PCI

Peripheral Component Interconnect

Conventional PCI is a computer bus for attaching hardware devices in a computer...

, PCI Express

PCI Express

PCI Express , officially abbreviated as PCIe, is a computer expansion card standard designed to replace the older PCI, PCI-X, and AGP bus standards...

, and AGP. Slot 1

Slot 1

Slot 1 refers to the physical and electrical specification for the connector used by some of Intel's microprocessors, including the Pentium Pro, Celeron, Pentium II and the Pentium III...

 and Slot A

Slot A

Slot A refers to the physical and electrical specification for a 242-lead single-edge-connector used by early versions of AMD's Athlon processor.The Slot A connector allows for a higher bus rate than Socket 7 or Super Socket 7...

 also used edge connectors; the processor

Central processing unit

The central processing unit is the portion of a computer system that carries out the instructions of a computer program, to perform the basic arithmetical, logical, and input/output operations of the system. The CPU plays a role somewhat analogous to the brain in the computer. The term has been in...

 being mounted on a card with an edge connector, instead of directly to the motherboard as before and since.

IBM PC

IBM PC

The IBM Personal Computer, commonly known as the IBM PC, is the original version and progenitor of the IBM PC compatible hardware platform. It is IBM model number 5150, and was introduced on August 12, 1981...

s used edge connector sockets attached to ribbon cables to connect 5.25" floppy disk drives. 3.5" drives use a pin connector instead.

Video game cartridges typically take the form of a PCB with an edge connector: the socket is located within the console itself. The Nintendo Entertainment System

Nintendo Entertainment System

The Nintendo Entertainment System is an 8-bit video game console that was released by Nintendo in North America during 1985, in Europe during 1986 and Australia in 1987...

 was unusual in that it was designed to use a zero insertion force edge connector: instead of the user forcing the cartridge into the socket directly, the cartridge was first placed in a bay and then mechanically lowered into position.