A method including clamping an integrated circuit package substrate between first and second supporting substrates; exposing the clamped package substrate to a heat source from a single direction; and modifying a shape of the package substrate. An apparatus including a first and second supporting substrates, the first supporting substrate including a two-dimensional area that is 75 percent to 95 percent of the area of the first side of the package substrate and the second supporting substrate including a two-dimensional area that is at least equivalent to the area of a package substrate and each of the first supporting substrate and the second supporting substrate include a body having a cavity therein such that when assembled on opposite sides of a package substrate, each cavity has a volume dimension such that the body of the supporting substrate is not in contact with an area of a package substrate.