Research On Key Process Of High Performance Thermal Wind Sensor

With the development of semiconductor technology,the MEMS thermal wind sensor has gradually replaced the traditional anemometer with movable structure,based on its small size,low power consumption and mass production.It is widely used in the fields of weather forecasting,traffic guidance,agricultural planting and industrial manufacturing.In this paper,a packaging method of MEMS thermal wind sensor based on low temperature cofiring ceramic(LTCC)technology is proposed.It aims at improving the sensor consistency problem caused by the inhomogeneity of the conductive adhesive,reducing the area of the packaging layer,providing support for the chip insulation slot,and improving the sensitivity of the anemometer.Firstly,the simulation of wind sensor is carried out by COMSOL,and its performance is preliminarily verified.Secondly,the process of low temperature cofired ceramic is studied.The thermal stress simulation is carried out by COMSOL to provide guidance for the experiment.Then the process is adjusted to make the ceramic completely sintered on the surface of the silicon wafer,and ensure its adhesion,density,and thermal stress meet the requirements of wind sensor packaging.Finally,the experimental samples are tested and analyzed.The best experimental parameters are found through the analysis of the surface morphology,density,thickness shrinkage,adhesion and thermal stress of the samples of different experimental parameters.The experiment shows that the density is within the allowable range when the speed coefficient of the homogenizing machine is between 7.5-12.5.the heating rate is 10 degrees /min.When the fluidity of the glass meets the requirements of sintering,the minimum sintering temperature is 850 degrees.the time of the glass melt can be given enough time when the holding time is 3h.when the ceramic ratio is 50%,the porosity is about 7%,and the porosity close to 0 while the ceramic ratio is 40%.