Package-Tolerant MEMS Thermal Wind Sensors Using SIG Technology

To minimize the effect by asymmetry of package, a novel chip-level thermal management method is proposed in this article, whereby the heat generated by the central heating resistor is confined within the chip itself. A thermal resistance model was established to analyze heat conduction and thermal convection, studying the influence of the thermal characteristics of substrate and packaging materials on heat distribution, which was further validated through the finite element method (FEM). The sensor was fabricated on the substrate of silicon in glass (SIG), allowing for front-side wind sensing and backside wire bonding. After package, the thermal imaging experiment was performed, showing that the produced heat concentrated on the glass film of the chip, while the silicon substrate portion remained close to ambient temperature. On this basis, wind tunnel experiments were conducted on four groups of the same sensors with different packaging offsets. The results reveal that in the presence of packaging deviation, the difference in wind speed and direction error (DE) between offset and nonoffset packaging was about 1.18% and 2.2°, respectively. Moreover, when the wind speed varied from 0 to 28.1 m/s, the maximum wind speed and wind DEs of the four sensor groups were no more than 2.81% and ±3.2°, respectively.