A weight optimized stiffener for use in a semiconductor device is disclosed herein. In one example, the stiffener is made of AlSiC for its weight and thermal properties. An O-ring provides sealing between a top surface of the stiffener and a component of the semiconductor device and adhesive provides sealing between a bottom surface of the stiffener and another component of the semiconductor device. The stiffener provides warpage control for a lidless package while enabling direct liquid cooling of a chip or substrate.