Patent ID: 8186213

Claim:
A thermal-type flowmeter comprising: a passage into which a measurement-target fluid is introduced; and a sensor element which is provided in the passage and which measures a flow rate of the measurement-target fluid, the sensor element including a semiconductor substrate; a hollow portion formed in the semiconductor substrate, and a heating resistor formed on an electric insulating film above the hollow portion, the sensor element measuring the flow rate of the measurement-target fluid by radiating heat from the heating resistor to the measurement-target fluid, wherein when Lh is a length of the heating resistor in a direction perpendicular to a flowing direction of the measurement-target fluid and Wd is the shortest distance between an upstream-side edge of the heating resistor and a peripheral edge of the hollow portion in the flowing direction of the measurement-target fluid, Wd≧0.4×Lh is satisfied in a relation between Lh and Wd.