A method for assembling die packages includes attaching contacts on a first side of a plurality of first die to substrate pads on a top surface of a composite carrier. The composite carrier includes a package substrate including at least one embedded metal layer having its bottom surface secured to a semiconductor wafer. The composite carrier minimizes effects of the CTE mismatch between the die and the package substrate during assembly reduces warpage of the die. After the attaching, the semiconductor wafer is removed from the package substrate. Electrically conductive connectors are attached to the bottom surface of the package substrate, and the package substrate is sawed to form a plurality of singulated die packages.