A method includes molding a device die in a molding material, wherein a metal pillar of the device die is exposed through a surface of the molding material. A substrate is adhered to the molding material. The substrate includes a redistribution layer that further includes redistribution lines. A plating is performed to fill a through-opening in the substrate to form a through-via. The through-via is plated on the metal pillar of the device die. An electrical connector is formed to electrically couple to the through-via.