Thermal control of mems mirrors to limit resonant frequency shift

Abstract

A micro-electromechanical system (MEMS) apparatus has an array of micro-mirrors and a control circuit for rotating the micro-mirrors synchronously at a resonant frequency. The MEMS apparatus includes elements with different Coefficients of Thermal Expansion (CTE) for a die substrate coupled to the array of micro-mirrors, a die attach layer, a chip package coupled to the die substrate and a printed circuit board coupled to the chip package. The apparatus provides mechanisms for reducing changes in the resonant frequency due to changes in temperature causing stresses due to a mismatch between the CTE of the different elements. A thermoelectric cooler is used, along with the optional addition of heating resistors, additional pins to distribute stress, and the widened vias allowing room for the pins to bend and relieve stress on the chip package.