The Study on Diaphragm's Mechanical Properties of Hot-Film Air Flow Sensor

In this paper, the diaphragms Mechanical property of Hot-film air flow sensor is studied on the base of proposition of double-sided convection heat air flow sensor. This diaphragm consists of barrier layer, support layer and passivation layer. For Hot-film air flow sensor, the Diaphragms Mechanical property is mainly up to the support layer, and the support layer is composed of Si3N4. In this research, four types of air flow sensors with different thickness of the support layer is prepared and tested at different air flow velocity. On the same time, the stress analysis of the sensor diaphragm is simulated at the flow rate of 5m/s by the finite element software. A conclusion can be drawn that the thickness of support layer can not be less than 1000nm, when the air flow velocity is more than 5m/s.