Guggi Kofod

Modelling the deformations during the manufacturing of nanostructures on non-planar surfaces for injection moulding tool inserts

This paper presents a new manufacturing process for transferring nanostructures from a glass wafer to a curved aluminium insert for polymer injection moulding. A nanostructure consisting of sinusoidal cross-gratings with a period of 426 nm is successfully transferred to hemispheres with different radii via an embossing process. The embossing is done into a glass-like resist called HSQ, using a 50 μm thick nickel foil, manufactured with electroforming. During the imprinting process the nickel foil is stretched due to the curved surface of the aluminium substrate and it is experimentally possible to characterize this stretch by counting the periods of the cross-gratings via SEM characterization. A numerical model for simulating the deformation of the nickel foil during nanoimprint is also developed, utilizing non-linear material and geometrical behaviour. Good agreement between measured and numerically calculated stretch ratios on the surface of the deformed nickel foil is shown, and from the model it is also possible to predict the limiting boundary of the nanostructures on the curved surfaces, with decreasing radii.

Modelling the deformation of nickel foil during manufacturing of nanostructures on injection moulding tool inserts

In the present work, a manufacturing process for transferring nanostructures from a glass wafer, to a double-curved insert for injection moulding is demonstrated. A nanostructure consisting of sinusoidal cross-gratings with a period of 426u2005nm is successfully transferred to hemispheres on an aluminium substrate with three different radii; 500u2005µm, 1000u2005µm and 2000u2005µm, respectively. The nanoimprint is performed using a 50u2005µm thick nickel foil, manufactured using electroforming. During the imprinting process, the nickel foil is stretched due to the curved surface of the aluminium substrate. Experimentally, it is possible to address this stretch by counting the periods of the cross-gratings via SEM characterization. A model for the deformation of the nickel foil during nanoimprint is developed, utilizing non-linear material and geometrical behaviour. Good agreement between measured and numerically calculated stretch ratios on the surface of the deformed nickel foil is found, and it is shown, that from the mode...