PGA
Initialism of pin grid array, a type of integrated circuit package, describing the electrical connections to circuit boards on which such a package is mounted.
PGA: processor package with pins on the bottom
A pin grid array (PGA) is a square integrated circuit package with pins arranged in a regular grid pattern on its underside. These pins push through holes drilled in the circuit board and solder into place, creating both mechanical and electrical connections. The package itself is typically ceramic or plastic, and the pins are usually made of copper alloy. PGA packages range from around 0.1 inches to 0.15 inches in pitch (center-to-center spacing), with pin counts from roughly 100 to over 600 depending on the die complexity and application.
PGA packaging was standard for high-performance processors from the late 1980s through the early 2000s. Intel used it for Pentium, Pentium Pro, and Pentium II processors; AMD used it for K6 and early Athlon chips. The regular grid layout made assembly straightforward and allowed for relatively easy socketing, which meant users could upgrade processors without replacing the motherboard. This was a significant advantage in an era when processor speeds were climbing rapidly and socket standards changed frequently.
Variants and related packages
Socket-based PGA packages (where the processor plugged into a zero-insertion-force socket) are distinct from land grid arrays (LGA), which replaced them. LGA packages have pads instead of protruding pins, with the complementary pins built into the socket itself. This shift allowed higher pin density and lower cost manufacturing. Ball grid arrays (BGA), used in graphics cards and mobile processors, use small solder balls instead of pins, enabling even denser layouts and better thermal properties.
The main weakness of PGA is mechanical fragility. Pins bend easily during handling, and a single bent pin can render the chip unusable. Solder joints beneath the package are also difficult to inspect visually after assembly, requiring X-ray examination to verify joint quality. The through-hole design also limits how tightly components can be packed on a motherboard and makes automated assembly more time-consuming than later surface-mount alternatives.
Today PGA survives mainly in niche industrial and server applications where pin-through-hole construction remains preferred for board durability and repairability. The term appears frequently in legacy documentation and in discussions of vintage computing hardware.