A wafer level fan out package includes a semiconductor die having a first surface, a second surface, and a third surface. A stiffener is disposed on the third surface of the semiconductor die. A conductive via passes through the stiffener. First and second electrically conductive patterns electrically connected to the conductive via are disposed on the first and second surfaces of the semiconductor die and stiffener. Solder balls are electrically connected to the first or second electrically conductive patterns.