JP2006133243A - Flow sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flow sensor configured to be capable of enhancing responsiveness and sensitivity. <P>SOLUTION: The flow sensor 1 comprises a substrate 4 whose front surface 4a faces a flow passage 3 of a fluid 2 to be measured, and a flow-passage forming member 5 and a plate 6 disposed to face each other across the substrate 4. The substrate 4 is made of stainless steel and formed in the shape of a thin plate with a plate thickness of about 50 to 150 μm. An electrically insulating film is formed on the side 4b of the substrate 4 opposite to the flow passage 3, and a temperature detection means 7 for measuring the flow velocity (flow rate) of the fluid 2, an ambient temperature sensor 8, an electrode pad 9 and a metallic thin film 10 for wiring are formed thereon. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a flow sensor for measuring the flow velocity or flow rate of a fluid flowing in a flow path, and more particularly to a thermal flow sensor.

  As a thermal type flow sensor that measures the flow rate and flow rate of a fluid, a type that causes a bias in the spatial temperature distribution of the fluid due to heat generated from a heating element (heater) and detects this with a temperature sensor (side Thermal type) and a type (self-heating type) that detects a change in electric power and a change in resistance due to heat deprived from heat by a fluid and detects a flow rate or a flow rate are known.

  Conventionally, this type of flow sensor has been mainly used for a non-corrosive gas, but recently, a sensor that can be used for a liquid or a corrosive gas has been developed. For example, a thermistor flow rate sensor and a liquid flow rate sensor disclosed in Patent Document 1 are known as an example.

The flow rate and flow rate sensor described in Patent Document 1 is formed with a heating element and its electrode on one surface of a plate-like substrate made of alumina, SiO ₂ or the like, and this heating element is covered with an insulator. A thermistor that measures the temperature of the heating element and its electrode are formed on the insulator, and the opposite surface is secured to the inner surface of the cover (container) with an adhesive to completely isolate the sensor from the fluid. . The cover has a good thermal conductivity and is made of a metal having good corrosion resistance against the fluid to be measured, such as stainless steel (SUS316L). Therefore, problems such as wear and corrosion do not occur more than the flow rate sensor of Patent Document 1 described above, and the reliability can be improved.

JP-A-8-146026

  However, since the flow velocity and flow rate sensor described in Patent Document 1 has the sensor fixed to the inner surface of the cover with an adhesive, the heat conduction efficiency between the fluid and the sensor decreases, and the heat capacity of the sensor also increases. There was a problem that sensitivity and response speed were lowered. Another problem is that the characteristics vary depending on the amount of adhesive used.

  The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide a flow sensor capable of improving responsiveness and sensitivity.

  To achieve the above object, according to a first aspect of the present invention, there is provided a flow sensor having a flow path through which a fluid flows, a thin plate-shaped substrate, a flow path forming member disposed so as to face the substrate, and a heat sink. And the flow path includes the substrate and the flow path forming member, and includes a temperature detection unit including a heating element on the surface opposite to the flow path side of the substrate and the heat sink member. Is.

  According to a second aspect of the present invention, in the flow sensor having a flow path through which the fluid flows, the flow path includes at least a thin plate-shaped substrate, a flow path forming member as a heat sink member, and a package. Is attached to a sensor mounting hole provided in a flow path forming member as the heat sink member and has an opening on a surface in contact with the fluid of the flow path, and the substrate generates heat on a surface opposite to the flow path side. A temperature detecting means including a body is provided to cover the opening of the package.

  In the first invention, since the temperature detection means is not exposed to the fluid, there is little possibility that dust accumulates or changes with time due to the fluid, and maintains stable performance. Since the substrate is a thin plate-like body, heat conduction between the fluid and the temperature detecting means is good.

  In the second invention, it is only necessary to insert the package into the sensor mounting hole of the flow path forming member, so that no special device, parts, etc. are required, and it can be easily mounted on the flow path forming member.

  Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings. 1A, 1B, and 1C are a front view, a sectional view, and a rear view showing an embodiment of a flow sensor according to the present invention 1, and FIG. 2 is a front view of a sensor unit. In these drawings, the flow sensor 1 is a flow path disposed so that the surface 4a side faces the substrate 4 facing the flow channel 3 of the fluid to be measured (hereinafter referred to as fluid) 2 with the substrate 4 interposed therebetween. It consists of a forming member 5 and a plate 6, and the substrate 4 and the flow path forming member 5 form a part of the flow path 3. The flow path forming member 5 and the plate 6 are joined by welding, brazing, bolts, or the like.

  The substrate 4 is formed in an elongated rectangular thin plate shape, and an outer peripheral edge portion is bonded to the back surface of the flow path forming member 5. The material of the substrate 4 is preferably a material having low thermal conductivity and high heat resistance, corrosion resistance, and rigidity. For this reason, in the present embodiment, the sensor unit 4A having a diaphragm structure is formed by being made of thin stainless steel having a plate thickness of about 50 to 150 μm, and its central portion is separated from the plate 6 and thermally insulated. Forming. In addition, when the board | substrate 4 is stainless steel, since intensity | strength will fall that the board thickness is 50 micrometers or less, it is unpreferable. On the other hand, if the thickness is 150 μm or more, the heat conduction efficiency in the direction parallel to the surface of the substrate increases while the heat conduction efficiency between the thickness direction of the substrate, that is, between the fluid and the temperature detecting means, decreases. It is not preferable.

  An electric insulating film (not shown) is formed on the back surface 4b, which is the surface opposite to the passage 3 side of the sensor unit 4A, and a temperature detecting means 7 for measuring the flow velocity (flow rate) of the fluid 2 and the ambient temperature. The sensor 8, the electrode pad 9, and the metal thin film 10 for wiring are formed by a known thin film forming technique. For example, it is formed by depositing a material such as platinum on the surface of the electrical insulating film and etching it into a predetermined pattern. The temperature detecting means 7 and the ambient temperature sensor 8 are respectively connected to the electrode pad 9 via the wiring metal thin film 10. Electrically connected.

The temperature detecting means 7 is formed at the center of the back surface of the sensor unit 4A. The ambient temperature sensor 8 is used to compensate for a change in the ambient temperature, that is, the fluid temperature, and is formed near the outer peripheral edge of the back surface of the sensor unit 4A. The electrical insulating film is made of, for example, a thin silicon oxide (SiO ₂ ) film having a thickness of about several thousand angstroms or a silicon nitride film. The silicon oxide film is formed, for example, by sputtering, CVD or applying a solvent mixed with silicon oxide and heating to a predetermined temperature to melt and solidify the silicon oxide. The silicon nitride film is formed by sputtering or CVD. The ambient temperature sensor 8 may be provided outside the sensor portion 4A of the substrate 4 soil or in a portion other than the substrate 4. The electrode pad 9 may also be provided on the substrate 4 soil outside the sensor unit 4A, and the electrode may be taken out therefrom.

  The temperature detecting means 7 for measuring the flow velocity (flow rate) generally has one heating element / temperature sensor, two heating elements / temperature sensors, and a heating element / temperature sensor and a temperature sensor. Conceivable.

  FIG. 2 shows an example in which the self-heating type temperature detecting means 7 is constituted by one heating element 11. Further, one ambient temperature sensor 8 is provided on the upstream side near the outer periphery of the back surface of the sensor unit 4A.

  FIG. 3 shows an example in which the self-heating type temperature detection means 7 is configured by two heating elements 11A and 11B. The two heating elements 11A and 11B are arranged close to the center of the back surface of the sensor unit 4A in the fluid 2 flow direction. Two ambient temperature sensors 8A and 8B are provided. These ambient temperature sensors 8A and 8B are formed near the outer periphery of the sensor portion 4A so as to face each other in a direction orthogonal to the flow direction of the fluid 2.

  FIG. 4 shows an example in which the indirectly heated temperature detecting means 7 is configured by one heating element 11 and two temperature sensors 12A and 12B. The heating element 11 is provided in the center of the back surface of the sensor unit 4A. The two temperature sensors 12A and 12B are arranged on the upstream side and the downstream side in the flow direction of the fluid 2 with the heating element 11 interposed therebetween. Further, one ambient temperature sensor 8 is provided on the upstream side in the flow direction of the fluid 2 at the outer peripheral portion of the back surface of the sensor unit 4A. The pattern width of the heating element 11 is preferably 10 to 50 μm, and the pattern widths of the temperature sensors 12A and 12B and the ambient temperature sensor 8 are preferably about 5 to 10 μm.

  FIG. 5 shows an example in which the self-heating type temperature detection means 7 is configured by two heating elements 11A and 11B. The two heating elements 11A and 11B are arranged close to the center of the back surface of the sensor unit 4A in the fluid 2 flow direction. One ambient temperature sensor 8 is provided on the upstream side in the flow direction of the fluid 2.

  FIG. 6 shows an example in which two heating elements 11A and 11B are arranged in the center of the back surface of the sensor unit 4A in the flow direction of the fluid 2 to constitute the self-heating type temperature detection means 7. Two ambient temperature sensors 8A and 8B are provided on the upstream side and the downstream side in the flow direction of the fluid 2 near the outer periphery of the back surface of the sensor unit 4A.

  FIG. 7 shows an example in which two heat generating elements 11A and 11B are similarly arranged in the center of the back surface of the sensor unit 4A in the flow direction of the fluid 2 to constitute a self-heating type temperature detecting means 7. One ambient temperature sensor 8 is provided on the back surface of the sensor unit 4A near the outer periphery in the direction orthogonal to the flow direction of the fluid 2.

  In FIG. 1, the flow path forming member 5 is made of an elongated metal plate, and a recess 14 having a depth slightly smaller than the substrate 4 and having a depth of about 0.5 to several mm is formed at the center of the back surface. And a space formed between the substrate 4 and the surface 4 a of the substrate 4 form a part of the flow path 3 of the fluid 2. Further, near the both ends of the flow path forming member 5 in the longitudinal direction, a fluid supply port 15 and a fluid discharge port 16 communicating with the flow path 3 are formed.

  The plate 6 is made of an elongated metal plate, and is in close contact with and joined to the back surface 4b of the substrate 4. Further, a through hole 17 having the same size as the sensor portion 4A of the substrate 4 is provided in the center of the plate 6, and the temperature detecting means 7 and the ambient temperature sensor 8 are electrically connected to the outside through the through hole 17. A connecting electrode 18 is provided. The electrode 18 is formed by fixing a plurality of metal pins 20 to the metal frame 19 via hermetic glass, and the inner end of the pin 20 is brazed to the electrode pad 9 of the sensor unit 4A. It is joined. When attaching the electrode 18, it is preferable to evacuate the through-hole 17 or attach a dry inert gas having a low thermal conductivity in a sealed space between the substrate 4 and the electrode 18. If it is not affected by the wind, it may be open to the atmosphere. Instead of using the electrode 18, the sensor electrode pad and the external circuit board may be connected by wire bonding using a gold wire.

  The material of the flow path forming member 5 is preferably a material having high heat conductivity, heat resistance, corrosion resistance, and rigidity because it also serves as a structural material and a heat sink. In addition, in order to apply the flow sensor 1 to a corrosive fluid, it is preferable that all the portions that come into contact with the fluid 2 are made of the same material having corrosion resistance. Preferably it is done. For this reason, in the present embodiment, the flow path forming member 5 is formed of stainless steel (particularly SUS316L) which is the same material as the substrate 4. Thus, if the board | substrate 4 and the flow-path formation member 5 are formed with stainless steel, it can join by using YAG laser welding etc., without using a dissimilar metal. Stainless steel is relatively excellent in workability and is suitable as a sensor material. However, not only stainless steel but also materials having high thermal conductivity such as sapphire and ceramics can be used because they can reduce the heat escape in the surface direction if they are formed so thin. The thermal conductivity of stainless steel, sapphire, and ceramics at 300K is about 16, 46, and 36 [W / mK], respectively, depending on the composition.

  The material of the plate 6 is preferably a material having high thermal conductivity, heat resistance, and rigidity because it also serves as a structural material and a heat sink. However, since it does not contact the measurement fluid, corrosion resistance is not so necessary.

  In the flow sensor 1 shown in FIG. 2 using one heating element 11, the flow velocity can be converted into a voltage signal by using a constant temperature difference circuit as shown in FIG. As shown in FIG. 11, the constant temperature difference circuit includes a bridge circuit including resistors R 1 and R 2, a heating element (resistance heater) 11, a resistor R 3 and an ambient temperature sensor 8, and a resistor R 1 and a heating element 11. An operational amplifier OP1 having a point voltage as an inverting input and a midpoint voltage of the resistor R2 and the resistor R3 as a non-inverting input is provided. The output of the operational amplifier OP1 is commonly connected to one end of the resistors R1 and R2 constituting the bridge circuit. Has been. Here, the resistance values of the resistors R1, R2, and R3 are set so as to be always higher than the ambient temperature sensor 8 by a certain constant temperature.

  If the fluid 2 is allowed to flow in the direction of the arrow in this state, for example, when the heat generating element 11 is deprived of heat by the fluid 2, the resistance value of the heat generating element 11 decreases and the equilibrium state of the bridge circuit is lost. -Since the voltage according to the voltage which arises between non-inverting inputs is added to a bridge circuit, the emitted-heat amount of the heat generating body 11 increases so that the heat deprived by the fluid 2 may be compensated. As a result, when the resistance value of the heating element 11 increases, the bridge circuit returns to an equilibrium state. Therefore, a voltage corresponding to the flow velocity is applied to the bridge circuit in an equilibrium state. The constant temperature difference circuit of FIG. 11 outputs the voltage between the terminals of the heating element 11 as a voltage output among the voltages applied to the bridge circuit at this time.

  Thus, the constant temperature difference circuit controls the current or voltage so that the temperature of the heating element 11 is higher than the ambient temperature measured by the ambient temperature sensor 8 to keep the temperature difference constant, The flow velocity or flow rate of the fluid 2 can be measured by detecting a current or power change.

  FIGS. 3 and 6 are combinations of two flow sensors shown in FIG. 2. By detecting a voltage difference between the heating element 11A on the upstream side and the heating element 11B on the downstream side with a circuit as shown in FIG. The flow rate or flow rate of fluid 2 and the direction of flow can be measured. In the circuit shown in FIG. 13, two constant temperature difference circuits shown in FIG. 11 are used, and the voltage difference between the terminals of the heating element 11A and the heating element 11B is amplified by the operational amplifier OP3 to obtain a voltage output. The flow rate can be determined by the magnitude of the voltage output, and the direction can be determined by the polarity. Although the voltage difference is taken here, a current or power difference may be taken.

  In the flow sensor shown in FIG. 5 and FIG. 7 using the two heating elements 11A and 11B, the flow rate and flow direction of the fluid can be detected using the constant temperature difference circuit shown in FIG.

  The circuit shown in FIG. 12 includes a bridge circuit composed of resistors R1 and R2, heating elements (resistance heaters) 11A and 11B, a resistor R3, and an ambient temperature sensor 8, and an operational amplifier OP1 that keeps the bridge circuit in a balanced state. In common with the constant temperature difference circuit shown in FIG. The circuit shown in FIG. 12 includes operational amplifiers OP2A and OP2B that respectively amplify voltages between terminals of two heating elements 11A and 11B connected in series, and an operational amplifier OP3 that receives a difference between these outputs as an operational amplifier OP3. Is output as a voltage output corresponding to the flow velocity of the fluid 2.

  When the bridge circuit of the constant temperature difference circuit as shown in FIG. 12 is energized, the fluid 2 is moved in the direction of the arrow in a state where the two heating elements 11A and 11B are heated to a certain temperature higher than the ambient temperature. When flowing, the heating element 11A located on the upstream side is cooled to lower the temperature. On the other hand, the temperature of the heating element 11B located on the downstream side rises due to heat conduction from the upstream heating element 11A using the flow of the fluid 2 as a medium, and a temperature difference is generated between the two heating elements 11A and 11B. This temperature difference is caught as a change in the resistance value of the heating elements 11A and 11B, and the flow rate or flow rate of the fluid 2 is measured by detecting the change in the resistance value or the voltage between both terminals and using it as a sensor output. In this case, when the temperature difference is detected using the two heating elements 11A and 11B, reproducibility and accuracy can be improved as compared with the case where one is used. Moreover, the flow direction of the fluid 2 can also be detected by the resistance change of the heating elements 11A and 11B.

  In the flow sensor shown in FIG. 4 using one heating element 11 and two temperature sensors 12A and 12B, the heating element 11 is more than the ambient temperature by energizing the bridge circuit of the constant temperature difference circuit as shown in FIG. When the fluid 2 is flowed in the direction of the arrow while being heated to a constant high temperature, a temperature difference is generated between the upstream temperature sensor 12A and the downstream temperature sensor 12B of the heating element 11, and as shown in FIG. The flow rate or flow rate of the fluid 2 is measured by detecting the voltage difference or resistance value difference by the circuit. Here, the circuit shown in FIG. 14 supplies a voltage output using a bridge circuit including two temperature sensors 12A and 12B, and the circuit shown in FIG. 15 includes two temperature sensors 12A and 12B connected in series. The voltage between the terminals is amplified by the operational amplifiers OP1 and OP2, respectively, and the difference is further amplified by the operational amplifier OP3 as the voltage output. In this case, since the two temperature sensors 12A and 12B are used, the flow direction of the fluid 2 can be detected, and this configuration has the best accuracy and reproducibility.

  In such a flow sensor 1, since the temperature detecting means 7 is provided on the surface of the substrate 4 made of a thin plate-like body on the opposite side to the surface in contact with the fluid 2, the temperature detecting means 7, the ambient temperature sensor 8. Measurement of corrosive gases and liquids used in semiconductor manufacturing equipment, etc. without electrode pad 9 etc. being in direct contact with fluid 2 to be corroded or deteriorated or attached to dust etc. The reliability and durability of the sensor can be improved.

  Further, since the substrate 4 is formed in a thin plate-like body with stainless steel having a low thermal conductivity, there is little heat conduction in the direction parallel to the surface, and the thickness direction of the substrate, that is, between the fluid 2 and the temperature detecting means 7. The heat conduction is good and the responsiveness can be improved. Stainless steel is excellent in heat resistance, corrosion resistance, workability and rigidity, and is suitable as a sensor material.

  FIGS. 8A, 8B, and 8C are a front view, a sectional view, and a rear view showing another embodiment of the present invention. The same components as those shown in FIGS. 1 and 2 are denoted by the same reference numerals, and the description thereof will be appropriately described.

  In this embodiment, a sensor mounting hole 31 is formed in the flow path forming member 30 that forms the flow path 3 of the fluid 2, and a flow sensor 32 is mounted in the sensor mounting hole 31. The flow path forming member 30 is formed of stainless steel.

  The flow sensor 32 includes a cup-shaped package 35 having a circular opening 33 at the center of the front surface, an open rear surface, and a flange 34 integrally provided at the rear end portion of the outer peripheral surface, and the outer peripheral portion of the package 35. It is comprised with the board | substrate 4 which covers the said opening part 33 by being joined to the front surface. The substrate 4 is formed of stainless steel into a thin plate-like body, and the temperature detecting means 7, the ambient temperature sensor 8, the electrode pad 9, and the wiring metal thin film 10 shown in FIG. ing. The substrate 4 is not limited to a square, but may be another shape such as a circle. Further, the configurations of the temperature detecting means 7 and the ambient temperature sensor 8 are not limited to those shown in FIG. 4, but may be those shown in FIG. 2, FIG. 3, FIG. 5, FIG. Further, the ambient temperature sensor 8 may be provided in a portion other than the substrate 4.

  The package 35 is made of stainless steel and is fitted into the sensor mounting hole 31 of the flow path forming member 30, and the flange 34 is joined to the back surface of the flow path forming member 30 by YAG laser welding or the like. The front surface of the package 35 and the surface of the substrate 4 form the same surface as the inner wall surface 30 a of the flow path forming member 30 and constitute a part of the flow path 3. An electrode 18 is incorporated into the package 35 from the opening on the back side, and the pin 20 is connected to the electrode pad 9 by brazing. In addition, you may connect with a circuit board by the wire bond by a gold wire from the electrode pad of a sensor.

  In the flow sensor 32 having such a structure, a sensor mounting hole 31 is formed in the flow path forming member 30, and the flow sensor 32 is fitted into the sensor mounting hole 31 so that the surface of the substrate 4 is brought into contact with the fluid 2. Since it is only necessary to join the package 35 to the flow path forming member 30, it is not necessary to use a special device, component, etc., and it can be easily attached. The flange 34 and the flow path forming member 30 may be joined with a bolt using a sealing material such as an O-ring.

  FIG. 9 shows the structure of the sensor unit 4A shown in FIG. 4, in which the temperature of the heating element 11 is set 30 ° C. higher than the ambient temperature in the air, and the heating elements 11 of the upstream and downstream temperature sensors 12A and 12B FIG. 10 is a diagram showing the relationship between the distance and the temperature difference between the two temperature sensors 12A and 12B when a simulation is performed while changing the distance of FIG. 10. FIG. 10 shows from the heater Rh (heating element) to the temperature sensors (Ru, Rd). It is a figure which shows the distance. As apparent from FIG. 9, the position where the temperature difference becomes the largest under these conditions was a position of 650 μm from the center of the heating element 11.

  As described above, the flow sensor according to the present invention is a flow sensor having a flow path through which a fluid flows. The flow path includes a thin plate-shaped substrate and a flow path forming member. Since the temperature detection means including the heating element and the heat sink member are provided on the surface opposite to the flow path side, the temperature detection means is not exposed to the fluid, so that there is little risk of dust accumulation or aging due to the fluid. , Can maintain stable performance. Since the substrate has a thin plate shape, heat conduction between the fluid and the temperature detecting means can be improved. As described above, a sensor with improved responsiveness and sensitivity can be provided. In addition, examples of the material of the substrate include stainless steel, sapphire, ceramics, and the like. Among these, stainless steel is a particularly suitable material in terms of corrosion resistance, workability, thermal conductivity, and rigidity. The thickness of the substrate should be as thin as possible in order to improve the heat conduction between the fluid and the temperature detection means and to reduce the heat conduction in the lateral direction in the substrate, but the conditions are workability, strength, handling It is necessary to determine in consideration of external factors such as production. For this reason, in the case of stainless steel, about 50-150 micrometers is optimal.

  Further, the present invention provides a flow sensor having a flow path through which a fluid flows, wherein the flow path includes a thin plate-shaped substrate, a flow path forming member as a heat sink member, and a package. And an opening on a surface of the flow path that is in contact with the fluid of the flow path that is attached to a sensor mounting hole provided in the flow path forming member as the heat sink member, and the heating element on the surface opposite to the flow path side Since the opening portion of the package is covered with the temperature detecting means including the above, it is possible to easily attach to the flow path forming member without requiring a special device or component.

(A), (b), (c) is the front view, sectional drawing, and rear view which show one Embodiment of the flow sensor which concerns on this invention. It is a front view of a sensor part. It is a front view which shows other embodiment of a sensor part. It is a front view which shows other embodiment of a sensor part. It is a front view which shows other embodiment of a sensor part. It is a front view which shows other embodiment of a sensor part. It is a front view which shows other embodiment of a sensor part. (A), (b), (c) is the front view, sectional drawing, and rear view which show other embodiment of this invention. It is a figure which shows the relationship between the distance and the temperature difference of two temperature sensors when changing the distance from the heat generating body of the temperature sensor of an upstream side and a downstream side. It is a figure which shows the distance from a heater (Rh) to a temperature sensor (Ru, Rd). It is a figure which shows a constant temperature difference circuit. It is a figure which shows another constant temperature difference circuit. It is a figure which shows another constant temperature difference circuit. It is a figure which shows a sensor output circuit. It is a figure which shows another sensor output circuit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Flow sensor, 2 ... Fluid, 3 ... Flow path, 4 ... Board | substrate, 4A ... Sensor part, 5 ... Flow path formation member, 6 ... Plate, 7 ... Temperature detection means, 8 ... Ambient temperature sensor, 9 ... Electrode pad DESCRIPTION OF SYMBOLS 10 ... Metal thin film for wiring, 11 ... Heat generating body (heater), 30 ... Channel formation member, 31 ... Sensor attachment hole, 32 ... Flow sensor, 35 ... Package.

Claims (2)

In a flow sensor having a flow path through which a fluid flows,
A thin plate-like substrate, and a flow path forming member and a heat sink member disposed so as to face each other with the substrate 4 interposed therebetween,
The flow path is constituted by the substrate and the flow path forming member, and has a temperature detection means including a heating element on the surface opposite to the flow path side of the substrate and the heat sink member. Flow sensor. In a flow sensor having a flow path through which a fluid flows,
The flow path is composed of at least a thin plate-shaped substrate, a flow path forming member as a heat sink member, and a package,
The package is attached to a sensor mounting hole provided in a flow path forming member as the heat sink member and has an opening on a surface in contact with the fluid of the flow path,
The flow sensor according to claim 1, wherein the substrate has temperature detection means including a heating element on a surface opposite to the flow path side to cover the opening of the package.

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