Ball grid array

A ball grid array (BGA) is a type of surface-mount packaging (a chip carrier) used for integrated circuits.

A BGA can provide more interconnection pins than can be put on a dual in-line or flat package.

[citation needed] Soldering of BGA devices requires precise control and is usually done by automated processes such as in computer-controlled automatic reflow ovens.

The BGA is descended from the pin grid array (PGA), which is a package with one face covered (or partly covered) with pins in a grid pattern which, in operation, conduct electrical signals between the integrated circuit and the printed circuit board (PCB) on which it is placed.

In a BGA the pins are replaced by pads on the bottom of the package, each initially with a tiny solder ball stuck to it.

The BGA is a solution to the problem of producing a miniature package for an integrated circuit with many hundreds of pins.

This allows heat generated by the integrated circuit inside the package to flow more easily to the PCB, preventing the chip from overheating.

BGAs, with their very short distance between the package and the PCB, have low lead inductances, giving them superior electrical performance to pinned devices.

As with all surface mount devices, bending due to a difference in coefficient of thermal expansion between PCB substrate and BGA (thermal stress) or flexing and vibration (mechanical stress) can cause the solder joints to fracture.

If a BGA is found to be badly soldered, it can be removed in a rework station, which is a jig fitted with infrared lamp (or hot air), a thermocouple and a vacuum device for lifting the package.

Pre-configured solder balls matching the array pattern can be used to reball BGAs when only one or a few need to be reworked.

For higher volume and repeated lab work, a stencil-configured vacuum-head pick-up and placement of loose spheres can be used.

A cheaper and easier inspection method, albeit destructive, is becoming increasingly popular because it does not require special equipment.