An integrated circuit structure includes a substrate, a PPI over the substrate, a solder region over and electrically coupled to a portion of the PPI, and a molding compound molding a lower portion of the solder region therein. A top surface of the molding compound is level with or lower than a maximum-diameter plane, wherein the maximum-diameter plane is parallel to a major surface of the substrate, and the maximum-diameter of the solder region is in the maximum-diameter plane.