A Ball Grid Array socket -- also known as a BGA socket -- is a central processing unit package characterized by soldered balls to accommodate a processor. Like other types of CPU sockets, the BGA socket is designed for physical and electrical connection of a processor with the motherboard of a personal computer.
Background
The BGA socket is considered a descendant of the Pin Grid Array, which consists of pin holes arranged in a neat, grid-like format on one side of a square-shaped substrate. This provides the interface for the processor to be connected to the motherboard -- not only for data transfer or interaction with other PC components, but also for protection from potential damage during insertion or removal. The BGA socket follows the same orderly layout of the contacts; however, instead of pins, it uses metal balls or spheres soldered onto the surface.
Types
The BGA socket has more than a dozen variants. However, the most popular ones include the Plastic BGA, Ceramic BGA and Flip Chip BGA. The PBGA and CBGA are named after the material used in their manufacture. The FCBGA is a reference to a variant that involves the back of the CPU's die -- the wafer of semiconductor material upon which its processing unit or units are placed -- exposed so that the user can introduce a heat sink to cool it down.
Advantages
The primary advantage of the BGA socket lies in its ability to fit more processor contacts in a substrate. This design solved the problem of mistakenly bridging pin contacts with solder as manufacturers increased their number on PGA sockets. The BGA socket uses the solder on the balls for attachment, rather than having them applied on the contacts. In addition to its density, which was higher than that of previous types of integrated circuit packaging, the BGA socket has better heat conduction and electrical performance, with a lower thermal resistance between the socket and the motherboard due to the shortened distance and relatively outstanding thermal properties of the socket itself.
Disadvantages
The BGA socket, however, also has its drawbacks. Its main shortcoming is the inability of its solder to flex like sockets with longer contacts. This causes an increase of the possibility of the motherboard's thermal and mechanical stresses being transferred to the socket, thus causing fracture of the solder balls and reducing its reliability. Another problem with the BGA socket is the difficulty of searching for soldering defects once it has been soldered onto the motherboard.
Tags: Grid Array, processing unit, sockets socket, solder balls, soldered onto