What is package-on-package?

Package-on-package (PoP) is a technology that allows the integration of multiple packages within a single device. It involves stacking two or more packaged integrated circuits (ICs) vertically, with interconnecting through solder balls, copper pillars, or other bonding techniques.

The bottom package is usually a logic device, while the top package is a memory device. PoP technology has become more popular with mobile and handheld devices that require higher memory density in a small form factor.

By stacking multiple packages, device manufacturers can reduce the overall area occupied by multiple components, which leads to smaller form factor devices. PoP also reduces interconnect length, which can improve signal integrity, reduce noise, and increase bandwidth.

PoP technology has some disadvantages, as well. It increases the complexity of the assembly process and may lead to a higher risk of defects, and there might be a thermal issue if there is no proper management of heat generated from such devices. Additionally, PoP devices can be more expensive to manufacture as they require higher precision equipment and processes.