Thermal type flow rate sensor

摘要

A thermal type flow rate sensor comprising a sensor chip having a rectangular shape. The sensor chip is supported between supporting pins through ribbon-like leads connected to opposite ends of the sensor chip. The ribbon-like leads serve to correctly locate the surface of the sensor chip with respect to flow of fluid. The surfaces of the sensor chip is formed with a thin film heater. A heater portion of the thin film heater comprises a plurality of straight portions and a plurality of turn portions connecting the straight portions to each other. Each turn portion is formed in a smoothly curved shape to avoid the concentration of electric currents and is disposed at an end portion of the sensor chip which has a comparatively low temperature. This structure is effective in preventing generation of cracks in the turn portions. In addition, the plurality of straight portions are alternatively inclined to effectively utilize the surface of the sensor chip to form a long heating portion.