In computer hardware, a CPU socket or CPU slot contains one or more mechanical components providing mechanical and electrical connections between a

microprocessor A microprocessor is a computer processor where the data processing logic and control is included on a single integrated circuit, or a small number of integrated circuits. The microprocessor contains the arithmetic, logic, and control circu ...

and a

printed circuit board A printed circuit board (PCB; also printed wiring board or PWB) is a medium used in electrical and electronic engineering to connect electronic components to one another in a controlled manner. It takes the form of a laminated sandwich str ...

(PCB). This allows for placing and replacing the

central processing unit A central processing unit (CPU), also called a central processor, main processor or just processor, is the electronic circuitry that executes instructions comprising a computer program. The CPU performs basic arithmetic, logic, controlling, an ...

(CPU) without soldering. Common sockets have retention clips that apply a constant force, which must be overcome when a device is inserted. For chips with many pins, zero insertion force (ZIF) sockets are preferred. Common sockets include

Pin Grid Array A pin grid array (PGA) is a type of integrated circuit packaging. In a PGA, the package is square or rectangular, and the pins are arranged in a regular array on the underside of the package. The pins are commonly spaced 2.54 mm (0.1") ...

(PGA) or

Land Grid Array The land grid array (LGA) is a type of surface-mount packaging for integrated circuits (ICs) that is notable for having the pins on the socket (when a socket is used) rather than the integrated circuit. An LGA can be electrically connected to a ...

(LGA). These designs apply a compression force once either a handle (PGA type) or a surface plate (LGA type) is put into place. This provides superior mechanical retention while avoiding the risk of bending pins when inserting the chip into the socket. Certain devices use Ball Grid Array (BGA) sockets, although these require soldering and are generally not considered user replaceable. CPU sockets are used on the

motherboard A motherboard (also called mainboard, main circuit board, mb, mboard, backplane board, base board, system board, logic board (only in Apple computers) or mobo) is the main printed circuit board (PCB) in general-purpose computers and other expand ...

in desktop and server computers. Because they allow easy swapping of components, they are also used for prototyping new circuits. Laptops typically use

surface-mount Surface-mount technology (SMT), originally called planar mounting, is a method in which the electrical components are mounted directly onto the surface of a printed circuit board (PCB). An electrical component mounted in this manner is referred ...

CPUs, which take up less space on the motherboard than a socketed part. As the pin density increases in modern sockets, increasing demands are placed on the

fabrication technique, which permits the large number of signals to be successfully routed to nearby components. Likewise, within the

chip carrier In electronics, a chip carrier is one of several kinds of surface-mount technology packages for integrated circuits (commonly called "chips"). Connections are made on all four edges of a square package; compared to the internal cavity for mou ...

, the

wire bonding Wire bonding is the method of making interconnections between an integrated circuit (IC) or other semiconductor device and its integrated circuit packaging, packaging during Fabrication (semiconductor), semiconductor device fabrication. Altho ...

technology also becomes more demanding with increasing pin counts and pin densities. Each socket technology will have specific reflow soldering requirements. As CPU and memory frequencies increase, above 30 MHz or thereabouts, electrical signalling increasingly shifts to

differential signaling Differential signalling is a method for electrically transmitting information using two complementary signals. The technique sends the same electrical signal as a differential pair of signals, each in its own conductor. The pair of conduc ...

over parallel buses, bringing a new set of

signal integrity Signal integrity or SI is a set of measures of the quality of an electrical signal. In digital electronics, a stream of binary values is represented by a voltage (or current) waveform. However, digital signals are fundamentally analog in nature, ...

challenges. The evolution of the CPU socket amounts to a coevolution of all these technologies in tandem. Modern CPU sockets are almost always designed in conjunction with a

heat sink A heat sink (also commonly spelled heatsink) is a passive heat exchanger that transfers the heat generated by an electronic or a mechanical device to a fluid medium, often air or a liquid coolant, where it is dissipated away from the device, t ...

mounting system, or in lower power devices, other thermal considerations.

Function

A CPU socket is made of plastic, and often comes with a lever or latch, and with metal contacts for each of the pins or lands on the CPU. Many packages are keyed to ensure the proper insertion of the CPU. CPUs with a PGA (pin grid array) package are inserted into the socket and, if included, the latch is closed. CPUs with an LGA (land grid array) package are inserted into the socket, the latch plate is flipped into position atop the CPU, and the lever is lowered and locked into place, pressing the CPU's contacts firmly against the socket's lands and ensuring a good connection, as well as increased mechanical stability.

List of CPU sockets and slots

80x86

Table legend:

Other ISAs

Slotkets

Slotket In computer hardware terminology, slotkets, also known as slockets, (both short for ''slot to socket adapter'') are adapters that allow socket-based microprocessors to be used on slot-based motherboards. Slotkets were first created to allow the u ...

s are special adapters for using socket processors in bus-compatible slot motherboards.

References

External links

Socket ID Guide

CPU Sockets Chart
- A fairly detailed table listing x86 Sockets and associated attributes.
techPowerUp! CPU Database

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