Package structures and methods for forming the same are provided. The method includes forming a passivation layer having an opening and forming a first seed layer in the opening. The method further includes filling the opening with a conductive layer over the first seed layer and bonding an integrated circuit die to the conductive layer over a first side of the passivation layer. The method further includes removing a portion of the first seed layer to expose a top surface of the conductive layer and to partially expose a first sidewall of the passivation layer from a second side of the passivation layer and forming a second seed layer over the top surface of the conductive layer and over the first sidewall of the passivation layer.