Characterisation and prediction of thermo-mechanical and hygroscopic behaviour of oriented semicrystalline polymer foils

The project aims at understanding and predicting the effects of time, stress, temperature and humidity on the mechanical response of thin semicrystalline polymer foils during lithographic processing.

The Holst Centre has a strong interest in understanding and predicting the dimensional stability of flexible substrates, in particular PEN and PET foils, that are used to manufacture plastic electronics in a cost-effective roll-to-roll process. In particular, in the case of transistor patterning for instance, to make the backplane of a flexible display or to construct a plastic memory for RFID (radio frequency identification), high registration accuracy is required. The objective of this project is to develop a multi-scale modelling tool to predict the time-dependent micro-deformation of PEN and PET foils which occurs during processing such as lithography and foil handling. In order to form and assess the validity of this model, an experimental programme is carried out which maps the viscoelastic properties of the foils by stress and strain controlled mechanical measurement of the inherent molecular transitions.

PhD researcher: Michael Poluektov
Supervisors: Hans van Dommelen, Leon Govaert, Marc Geers
Financing: Materials inovation institute (M2i)

A micromechanical model is developed to predict the dimensional stability (instantaneous and residual shrinkage/expansion) of foils when exposed to heat, moisture and/or a solvent, and mechanical loads. These predictions enable a further optimisation of the patterning processes on flexible substrates and the development of compensation algorithms for maskless imaging on flexible substrates. The model will also be applicable to foil behaviour on a carrier and the behaviour of other oriented semi-crystalline polymers.