A device includes a semiconductor chip, a molding compound, an insulating structure, an under-bump-metallurgy (UBM), a conductive ball, and a protection layer. The molding compound laterally surrounds the semiconductor chip. The insulating structure is over the semiconductor chip and the molding compound. The UBM is over the insulating structure and is electrically connected to the semiconductor chip. The conductive ball is in contact with the UBM. The protection layer extends from the UBM to the molding compound.