As a new type of SMD, the BGA evolved from the PGA (pin grid array) and usually consists of a core cavity, base, lead, cover, and spherical pins. The properties of BGA include:
? Higher pin count. In an SMD of the same package size, the BGA can have more pins. Typically, BGA assemblies come with 400 spherical pins. For example, a BGA with an area of 32mm by 32mm can hold up to 576 pins, while a QFP with the same area can only hold 184 pins.
? Smaller assembly area. With the number of pins, the BGA can accommodate a smaller assembly area. For example, compare a QFP with 304 pins to a BGA with 313 pins, which takes up a third less area, although the latter has more pins.
? Lower assembly height. The assembly height of BGA is lower than the sum of package thickness and ball height. For example, a QFP with 208 pins or 304 pins has a height of 3.78mm, while a BGA with 225 or 313 pins has a height of only 2.13mm. In addition, the assembly height of the BGA will be reduced after welding, because the welding ball will melt during welding.