Packages structure and methods of forming them are discussed. A structure includes a first die, a first encapsulant at least laterally encapsulating the first die, and a redistribution structure on the first die and the first encapsulant. The second die is attached by an external electrical connector to the redistribution structure. The second die is on an opposite side of the redistribution structure from the first die. A second encapsulant is on the redistribution structure and at least laterally encapsulates the second die. The second encapsulant has a surface distal from the redistribution structure. A conductive feature extends from the redistribution structure through the second encapsulant to the surface of the second encapsulant. A conductive pillar is on the conductive feature, and the conductive pillar protrudes from the surface of the second encapsulant.