Step height measurement of microscale thermoplastic polymer specimens using contact stylus profilometry

• A practical elastic–viscoplastic model for modeling the polymer surface deformation.
• A stylus-profiling based methodology to determine the viscous material properties.
• Experimental validation of the proposed methodology and error compensation model.

Quantitative characterisation of the dimensions of micro-scale polymer specimens imposes higher demands on stylus profilometry. Due to the weak and time-dependent mechanical properties of polymers, one of the main error sources within tactile dimensional measurement for polymeric structures comes from the surface deformation of specimens under stylus scanning with a certain probing force. In this paper, a practical elastic–viscoplastic model is proposed for modelling the (steady-state) polymer deformations during tactile surface scanning. To experimentally determine the viscous material properties of polymers necessary for the proposed analytical model, a stylus-profiling based methodology has been developed. The feasibility of the proposed methodology and a measurement error compensation model has been experimentally verified. Preliminary experimental investigation on measurement of polymeric step height specimens with currently available stylus profilometers demonstrates that the specimen deformation induced tactile measurement deviation can be evidently reduced.