US Patent 10529697 Package structure and method of forming the same

An embodiment is a structure including a first package including a first die, and a molding compound at least laterally encapsulating the first die, a second package bonded to the first package with a first set of conductive connectors, the second package comprising a second die, and an underfill between the first package and the second package and surrounding the first set of conductive connectors, the underfill having a first portion extending up along a sidewall of the second package, the first portion having a first sidewall, the first sidewall having a curved portion and a planar portion.