Methods and apparatus for performing molding on die on wafer interposers. A method includes receiving an interposer assembly having a die side and an opposite side including two or more integrated circuit dies mounted on the die side of the interposer, the interposer assembly having spaces formed on the die side of the interposer between the two or more integrated circuit dies; mounting at least one stress relief feature on the die side of the interposer assembly in one of the spaces between the two or more integrated circuit dies; and molding the integrated circuit dies using a mold compound, the mold compound surrounding the two or more integrated circuit dies and the at least one stress relief feature. An apparatus is disclosed having integrated circuits mounted on a die side of an interposer, stress relief features between the integrated circuits and mold compound over the integrated circuits.