BGA

BGA stands for Ball Grid Array, a type of surface-mount packaging used for integrated circuits. In a BGA, the interconnections are made by an array of solder balls on the underside of the package, arranged in a grid that mates with a corresponding land grid on the printed circuit board. This configuration allows a high I/O density with a relatively small footprint and improved heat dissipation compared with perimeter-pin packages.

Construction and variants: A BGA package typically consists of a ceramic or plastic encapsulation, an internal die attach, wire bonds or flip-chip bumps, and an array of solder balls on the bottom. Balls are usually made of lead-free SnAgCu, with ball pitch ranging from about 0.4 mm to 1.0 mm. Packages can be plastic BGA, ceramic BGA, or flip-chip BGA, where bumps on the die connect directly to the package substrate or to an interposer, and the balls on the bottom connect to the PCB.

Advantages and challenges: The grid of balls provides many connections with good thermal performance, especially when an exposed metal pad or heat spreader is used. However, inspecting solder joints is challenging: defects beneath the package often require X-ray imaging, and rework can be difficult. Warpage, voids, and solder-ball reliability are considerations in thermal cycling.

Applications: BGA is widely used for processors, graphics chips, network devices, and other high-pin-count ICs. It is commonly reflow-soldered onto PCBs and often paired with underfill for mechanical reliability.