Patent ID: 7219544

Claim:
A thermal-type flow rate sensor comprising: a flow rate detecting chip including a substrate having a thin wall portion, and a flow rate detecting portion having a heater located in the thin wail portion; a circuit chip electrically connected to the flow rate detecting portion through a first connecting wire and having a circuit portion for controlling input and output of the flow rate detecting portion; a lead portion electrically connected to the circuit portion through a second connecting wire; a support member having a groove portion the flow rate detecting chip being attached in the groove portion at a lower surface of the flow rate detecting chip; and a mold material, which is formed through a mold forming, to integrally cover a predetermined range including the circuit chip, connecting parts of the first connecting wire with the flow rate detecting portion and the circuit portion, and connecting parts of the second connecting wire with the circuit portion and the lead portion, so as to expose a part of the flow rate detecting portion including the heater to a measured fluid, wherein: the flow rate detecting chip is located in the groove portion of the support member to have a clearance with the groove portion and to form a cavity part inside the thin wall portion; the cavity part communicates with an outside of the thin wall portion through a communicating portion that includes the clearance; and the clearance is blocked by a filler material, at least at a portion of the filler material being positioned in the predetermined range, the filler material being disposed to prevent the mold material from entering the clearance in the mold forming, the filler material having been flowed into a position located between a side surface of the groove portion and a side surface of the flow rate detecting chip, the filler material flanking an end surface of the flow rate detecting chip.