Effect of Electrical Contact on the Contact Residual Stress of a Microrelay Switch.

Yung-Chuan Chen,Wei-Hua Lu,Hsun-Heng Tsai,Li-Wen Chen

doi:10.3390/s7112997

Yung-Chuan Chen, Wei-Hua Lu + Show 2 more

Open Access

https://doi.org/10.3390/s7112997

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Abstract

This paper investigates the effect of electrical contact on the thermal contactstress of a microrelay switch. A three-dimensional elastic-plastic finite element model withcontact elements is used to simulate the contact behavior between the microcantilever beamand the electrode. A model with thermal-electrical coupling and thermal-stress coupling isused in the finite element analysis. The effects of contact gap, plating film thickness andnumber of switching cycles on the contact residual stress, contact force, plastic deformation,and temperature rise of the microrelay switch are explored. The numerical results indicatethat the residual stress increases with increasing contact gap or decreasing plating filmthickness. The results also show that the residual stress increases as the number of switchingcycles increases. A large residual stress inside the microcantilever beam can decrease thelifecycle of the microrelay.

Highlights

Microrelays are widely used in the field of electromechanical control, telecommunications, test equipment, and other MEMS devices
A model with thermal-electrical coupling and thermal-stress coupling is used in finite element analysis to simulate interactions between the electricity, temperature and deformation arisen during the contact process
The elastic-plastic finite element model is used to investigate the effects of film thickness, contact gap and contact force on the contact deformation and residual stress distribution of the microrelay

Summary

Introduction

Microrelays are widely used in the field of electromechanical control, telecommunications, test equipment, and other MEMS devices. The magnetically actuated microrelay has the advantages of large actuating force, large displacement, low driving voltage as well as its insensitivity to the operating environment, which make it popular in many applications. To function well and to have a good reliability, the knowledge of design parameters, such as the contact gap, plating film thickness of the electrode, contact force, and contact resistance is required. Li and Zhang [4] used the finite element method to do the modal analysis of the microcantilever beam and to analyze the static deflection in the coil center of a magnetically actuated microrelay. A thermal elastic-plastic finite element model was utilized to calculate the residual stress distribution across the cantilever cross-section and to determine the beam tip deflection following heat treatment. The simulation data show that the residual stress increases with increasing contact gap or decreasing plating film thickness. A large residual stress inside the microcantilever beam can decrease the lifecycle of the microrelay

Theoretical Analysis

Finite Element Model

Results and Discussion

Conclusions