Abstract: A rupture testing procedure is carried out on metal foils at a number of process temperatures to evaluate their suitability for use in printed wire multilayer circuit boards. The test stand has a heated platen capable of heating foil test samples up to solder float temperatures (e.g. 550.degree. F.) and an interchangeable cover with a circular aperture that is selected to match the foil thickness. Gas under pressure is admitted to the platen and the unsupported part of the sample bulges out until the sample ruptures. A plot is made of samples for temperature, burst pressure, and bulge height at burst, and the results are used to accurately classify or grade the foil. Creep rupture can also be tested at elevated temperatures to provide further foil quality information.