Circuit board-microprocessor connection
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 💲 (PGA) or Land Grid Array (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 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 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.
Function [ edit ]
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 [ edit
]
80x86 [ edit ]
Table legend:
Intel only
AMD 💲 only
^ Some late model Socket 3
motherboards unofficially supported FSB speeds up to 66MHz ^ This is a double data 💲 rate
bus. FSB in the later models.
Slotkets [ edit ]
Slotkets are special adapters for using
socket processors in bus-compatible slot 💲 motherboards.
See also [ edit ]
