In accordance with some embodiments, a package-on-package (PoP) structure includes a first semiconductor package having a first side and a second side opposing the first side, a second semiconductor package having a first side and a second side opposing the first side, and a plurality of inter-package connector coupled between the first side of the first semiconductor package and the first side of the second semiconductor package. The PoP structure further includes a first molding material on the second side of the first semiconductor package. The second side of the second semiconductor package is substantially free of the first molding material.