Double stage FPCB scanning micromirror for laser pattern generation

This paper presents a double stage FPCB (Flexible Printed Circuit Board) electrostatic parallel plate (DSFP) micromirror. It is designed and fabricated base on mature commercial FPCB processes with low cost. The DSFP micromirror includes a FPCB moving electrode in the middle, two identical FR4 PCB fixed electrodes on both sides and a silicon mirror plate with aluminum coating. Compare with conventional MEMS micromirrors, it has much lower cost, shorter fabrication cycle and higher mirror surface quality. The performances of DSFP micromirror are modeled by Finite Element Analysis (FEA) software ANSYS. Prototypes are fabricated and tested. It can reach 3.25° average rotation angle with 100 V sinusoidal driving at 117 Hz resonance.

I. Introduction

Scanning micromirror [1] has a broad range of applications such as barcode reading [2], optical switch [3], image and pattern displays [4] [5], spectroscopy [6] and free space optical communication [7] due to its small size, low power consumption and fast speed. Most of the scanning micromirrors in current market are developed and fabricated through Microelectromechanical systems (MEMS) micromachining technology in a clean room. A MEMS micromirror could be driven by electrostatic [8]–[10], thermal [11], magnetic [12], and piezoelectric [13] method. Its aperture could be submillimeter to millimeters due to the micromachining process limitation. Some micromirrors have low flatness [14] [15] due to the residual stress [16]. In addition, it requires months or even years to develop and mature a self-designed microfabrication process for MEMS micromirrors.