A package substrate stack modeler includes a manufacturing modeler, configured to generate a model of a real package substrate stack based on an ideal design of the package substrate stack; a signal integrity model, configured to determine a signal integrity of a metal trace of the real package substrate stack; and a yield model, configured to determine a yield of the real package substrate stack; wherein the metal trace comprises a first value of a trace variable; further comprising a processor, configured to select a second value of the trace variable of the metal trace based on the determined signal integrity of the metal trace or the determined yield of the package substrate stack model.