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Pre-stresses Influence on a Micro Mirror Structure. Introduction. The purpose of the model is to exemplify the use of pre-stresses in plated metal layers in order to create a desired lift-off of a MEMS structure
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Introduction • The purpose of the model is to exemplify the use of pre-stresses in plated metal layers in order to create a desired lift-off of a MEMS structure • The model shows the use of the Initial Stresses feature in the Structural Mechanics Module
Model Geometry Mirror Cantilever beams as support Two-layers of plating
Problem Definition • Loads: • Pre-stresses of different signs but equal in magnitude for the upper and lower layer of the cantilevers • Constraints: • Cantilevers constrained in all directions at the free end surfaces • Materials • Alternative 1: Aluminum for both mirror and beams • Alternative 2: Aluminum for beams, stainless steel for mirror
Conclusions • The model shows that the curvature of the mirror and the lift-off from the substrate is substantially larger for aluminum • Steel gives a flatter mirror surface • The model can be quickly set-up and solve the COMSOL Multiphysics’ Structural Mechanics Module