Editing CPU socket (section)

{{Short description|Circuit board-microprocessor connection}}
[[File:AM5 Socket Open.jpg|thumb|[[Socket AM5]], a [[land grid array]] socket]]
[[File:Socket AM2.jpg|thumb|[[Socket AM2+]], a [[pin grid array]] socket]]

In [[computer hardware]], a '''CPU socket''' or '''CPU slot''' contains one or more mechanical components providing mechanical and electrical connections between a [[microprocessor]] and a [[printed circuit board]] (PCB). This allows for placing and replacing the [[central processing unit]] (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|pin grid array (PGA)]] or [[land grid array|land grid array (LGA)]]. These designs apply a [[compression (physics)|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 [[Lead (electronics)|pins]] when inserting the chip into the socket. Certain devices use [[Ball grid array|Ball Grid Array]] (BGA) sockets, although these require soldering and are generally not considered user replaceable.

CPU sockets are used on the [[motherboard]] in [[desktop computer|desktop]] and [[server (computing)|server]] computers. Because they allow easy swapping of components, they are also used for prototyping new circuits. [[Laptop]]s typically use [[surface-mount technology|surface-mount]] 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 [[printed circuit board]] fabrication technique, which permits the large number of signals to be successfully routed to nearby components. Likewise, within the [[chip carrier]], the [[wire bonding]] 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]] over parallel buses, bringing a new set of [[signal integrity]] 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]] mounting system, or in lower power devices, other thermal considerations.