A staggered pin grid array (SPGA) refers to a style of arranging pins on an integrated circuit package. It consists of two square arrays of pins, offset in both directions by half the minimum distance between pins in one of the arrays. Put differently: within a square boundary the pins form a diagonal square lattice. As with the pin grid array, there is generally a section in the middle of the package without any pins.
SPGA is usually used by devices that require a higher pin density than what a pin grid array can provide, such as microprocessors.