Through impulsive stimulated thermal scattering, the elastic and thermal properties of silicon-supported thin films (2-11 mu m thicknesses) of a new low-CTE (coefficient of thermal expansion) photosensitive polyimide based on a biphenyl dianhydride/p-phenylenediamine backbone were studied. The material was found to be mechanically anisotropic. The in-plane thermal diffusivity and the in-plane and through-plane shear and longitudinal sound speeds were determined.