A method includes forming a set of through-vias in a substrate, the set of through-vias partially penetrating a thickness of the substrate. First connectors are formed over the set of through-vias on a first side of the substrate. The first side of the substrate is attached to a carrier. The substrate is thinned from the second side to expose the set of through-vias. Second connectors are formed over the set of through-vias on the second side of the substrate. A device die is bonded to the second connectors. The substrate is singulated into multiple packages.