Abstract
Microtransfer printing is a sophisticated technique for the heterogeneous integration of separately fabricated micro/nano-elements into functional systems by virtue of an elastomeric stamp. One important factor influencing the capability of this technique depends on the adhesion between the viscoelastic stamp and the transferred element. To provide theoretical guidance for the control of adhesion in the transfer printing process, a finite element model for the viscoelastic adhesive contact between a polydimethylsiloxane (PDMS) stamp and a spherical transferred element was established, in which the adhesive interaction was modeled by the Lennard-Jones surface force law. Effects of the unloading velocity, preload, and thermodynamic work of adhesion on the adhesion strength, characterized by the pull-off force, were examined for a loading-dwelling-unloading history. Simulation results showed that the unloading path deviated from the loading path due to the viscoelastic property of the PDMS stamp. The pull-off force increased with the unloading velocity, and the increasing ratio was large at first and then became low. Furthermore, the influence of the preload on increasing the pull-off force was more significant under larger unloading velocity than that under smaller unloading velocity. In addition, the pull-off force increased remarkably with the thermodynamic work of adhesion at a fixed maximum approach.
Highlights
Microtransfer printing is an advanced technique in the area of material assembly and micro/nano manufacturing, which relies on the interfacial adhesion for integrating functional devices by transferring prefabricated micro/nano-elements from the growth substrate to the receiver substrate via a viscoelastic stamp [1]
4, which means thatset the element was moved the displacement in Figure the present analysis was totransferred follow a loading-dwelling-undownward to make contact with the stamp at a constant loading velocity until loading profile, shown in Figure 4, which means that the transferred element was moved reaching a preset maximum approach, dwelling for a few seconds, and retracting it downward to make contact with the PDMS stamp at a constant loading velocity until at a prescribed unloading velocity
The interfacial adhesion was simulated by the axial connector elements with nonlinear properties governed by the Lennard-Jones surface force law
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Microtransfer printing is an advanced technique in the area of material assembly and micro/nano manufacturing, which relies on the interfacial adhesion for integrating functional devices by transferring prefabricated micro/nano-elements from the growth substrate to the receiver substrate via a viscoelastic stamp [1]. The effects of work of adhesion on the transfer printing mechanics are unclear To solve these problems, this work was undertaken to establish a viscoelastic adhesive contact model between an elastomeric PDMS stamp and a spherical transferred element, and to realize the quantitative prediction of the interfacial adhesion. The surface interaction between the transferred element and the stamp by the Mooney-Rivlin strain energy function and the viscoelastic constitutive model was simulated by the axial connector elements with nonlinear properties governed by the characterizedforce-distance by the Prony series. The contact and separation processes between the stamp and the were simulated by the displacement control approach
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