A method includes placing a first package component and a second package component over a carrier. The first conductive pillars of the first package component and second conductive pillars of the second package component face the carrier. The method further includes encapsulating the first package component and the second package component in an encapsulating material, de-bonding the first package component and the second package component from the carrier, planarizing the first conductive pillars, the second conductive pillars, and the encapsulating material, and forming redistribution lines to electrically couple to the first conductive pillars and the second conductive pillars.