Package on a package (PoP) is an integrated circuit packaging method to vertically combine ball grid array (BGA) packages for discrete logic and memory. Two or more packages are installed atop each other, i.e. stacked, with a standard interface to route signals between them. PoP allows higher component density in devices, such as mobile phones, personal digital assistants (PDA), and digital cameras, at the cost of being slightly taller. Stacks with more than 2 packages are uncommon, due to heat dissipation considerations.