A method comprises determining a warpage of an integrated circuit (IC) package design. The IC package design includes a substrate having a top solder mask on a first major surface and a bottom solder mask on a second major surface opposite the first major surface. The first major surface has an IC die mounted over the top solder mask. The design is modified, including modifying an average thickness of one of the group consisting of the top solder mask and the bottom solder mask, so as to reduce the warpage. An IC package is fabricated according to the modified design.