US Patent 9837289 Methods for forming package-on-package structures having buffer dams

Package-on-Package (PoP) structures and methods of forming the same are disclosed. In some embodiments, a method of forming a PoP structure may include: plating at least one through-assembly via (TAV) over a peripheral region of a conductive seed layer; forming a dam member over a central region of the conductive seed layer; and placing a die over the central region of the conductive seed layer. The dam member may be laterally separated from the die and disposed between the die and the at least one TAV. The method may further include encapsulating the die, the dam member, and the at least one TAV in a polymer material.