The mechanical characterization of polymeric films is an important issue in many industries such as automobile, microelectronic or packaging where films are used as paint coating, photoresists, dielectric insulators and permeable coating. In particular, reliable and reproducible quantitative values of E' (storage) and E'' (loss modulus) are difficult to achieve.

Nanoindentation, the traditional and well established instrumental technique to have access to the Young Modulus and hardness, is however inappropriate for thin and low compliant materials. Indeed, such dc-nanoindentation experiments give a convolution of both the film and the substrate which is not straightforward to interpret.

In contrast to quasi-static measurements, the instrument can be used in ac mode by modulating the force; this mode enables quantitative studies of dynamic mechanical properties like viscoelasticity.

We have designed a dynamical nanoindentation setup based on sample modulation, using a stacked ceramic sample actuator instead of standard bimorph, allowing spectroscopy and quantitative imaging measurements.E' and E" were imaged with a dual phase lock-in amplifier (R and f) from which E' and E'' have been calculated.

The input signal was the actual probe displacement relative to the sample and the reference the sample excitation voltage.Polymeric samples have been encapsulated with phenol formaldehyde resin.

Dynamical Mechanical Analysis and classical nanoindentation measurements on the resin where used to calibrate E' and E'' for the other samples.

Thin film of PolymethylMethacrylate/Polystyrene, a non miscible polymer blend, has been deposited on various substrates and mechanically characterised after different thermal and light sample excitation.

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