Mechanical modelling of microelectronic packages for design optimization requires the quantitative knowledge of a large number of physical parameters. Because of the composite nature of many components, and because relevant materials properties in the microscale often deviate from the bulk values, there is therefore a need for a variety of micromechanical testing techniques. These techniques include tension, compression, shear, bending, and fatigue testing of samples with sizes in the 10 micron range. A novel technique has been developed for the testing the z-direction properties of thin films with displacements in the sub-micron range. Mechanical properties of thin films and surface regions may advantageously be probed by a continuous microindentation tester. All elastic properties of both isotropic and anisotropic packaging materials and components may be evaluated directly by the above methods, and the inelastic deformation behavior determined over many orders of magnitude of strain rate by load relaxation measurements. The above techniques and examples of their application will be discussed.