THERMAL FLOW METER

摘要

The present invention provides a thermal flow meter that is capable of minimizing a reduction in measurement accuracy due to deformation of a diaphragm and contamination on the rear surface, even when a void is provided in order to form a diaphragm on a flow rate detection element. The present invention is a thermal flow meter (300) provided with: an auxiliary passage for circulating a gas being measured (30), which has been taken in from a main passage (124); and a flow rate detection element for measuring the flow rate of the gas being measured (30) by transferring heat between the flow rate detection element and the gas being measured (30), which flows through the auxiliary passage. The thermal flow meter (300) is provided with at least a circuit package (400) that includes the flow rate detection element (602). A void (674) is formed on the rear surface of the flow rate detection element (602) in such a manner that a diaphragm (672) is formed in a flow rate detection region (437) of the flow rate detection element (602). The void (674) is an enclosed space in which the pressure has been reduced below the atmospheric pressure.