A method is presented for measuring the strength of thin films deposited on brittle substrates. The method has been successfully applied for Al and Cu films on quartz or Si substrates. A free-standing film region is produced through carefully breaking the substrate below the film starting from a diamond saw-cut. Due to delaminations along the interface the influence of the substrate is minimized. Because substrate breakage can be realized without damage of the ductile film an almost intact free-standing film covers the cracked substrate. The strength behavior of the thin metallic film is measured through applying a bending moment to the specimen, which loads the film by opening the substrate crack. The strength of the film is derived from the maximum of the load-deflection curve. The calculated strength values amount to about 2.3 GPa for e-beam evaporated 200 nm Al film, and 1.7 GPa for thermally evaporated 200 nm Al film. For 800 nm Al film a strength level of 0.74 GPa and for 800 nm Cu film 0.93 GPa is observed. These high strength values are suggested to be due to the size-effect of high geometrical constraint resulting from both the small thickness and active specimen length owing to difficult dislocation generation at submicron length scales. The proposed method proved to be suitable for the investigation of the strength properties of thin films of ductile materials on brittle substrates. (c) 2006 Elsevier B.V. All rights reserved.