WO2022064771A1

WO2022064771A1 - Physical quantity measurement device

Info

Publication number: WO2022064771A1
Application number: PCT/JP2021/020476
Authority: WO
Inventors: 博幸阿部; 孝之余語; ファハナービンティハリダンファティン; 瑞紀伊集院
Original assignee: 日立Astemo株式会社
Priority date: 2020-09-25
Filing date: 2021-05-28
Publication date: 2022-03-31
Also published as: JP2023165043A

Abstract

The present disclosure provides a physical quantity measurement device capable of suppressing a decrease in air flow rate measurement accuracy due to the influence of external sound pressure while suppressing an increase in the number of parts and an increase in the size of the device. The physical quantity measurement device comprises a damping member disposed between a thermal flow sensor and a lead frame. The thermal flow sensor includes a semiconductor substrate, a thin film portion which is formed on the surface side of the semiconductor substrate and exposed from a resin sealing portion, a flow rate detection portion provided on the front surface side of the thin film portion, and a recess which is formed on the back surface side of the semiconductor substrate and is adjacent to the back surface side of the thin film portion. The lead frame has a through hole that communicates with the opening of the recess, and a ventilation groove that communicates with the through hole and is formed along the back surface. A passage forming member forms a ventilation passage that allows the recess to communicate with the outside together with the through hole and the ventilation groove, and a portion that closes the through hole is exposed from the resin sealing portion. The damping member has a plurality of communication holes having an opening ratio that is set such that the coefficient of resistance to gas flowing between the ventilation passage and the recess is less than 2.76.

Description

Physical quantity measuring device

This disclosure relates to a physical quantity measuring device.

Conventionally, an invention relating to a thermal air flow sensor suitable for being installed in an intake system of an automobile engine to detect the intake air amount of the engine has been known (Patent Document 1 below). The thermal flow rate sensor described in Patent Document 1 includes a flow rate detection element and a support member (claim 1, paragraph 0010).

The flow rate detecting element has a diaphragm provided by processing a semiconductor substrate, a heat generation resistor provided on the diaphragm, and a resistance temperature detector provided on the upstream side and the downstream side of the heat generation resistor, respectively. .. The support member adheres and holds the flow rate detecting element via a sheet adhesive.

Further, the support member has a communication hole at which one side opens in the cavity provided on the back surface side of the diaphragm. The sheet adhesive has a ventilation hole, and the ventilation hole corresponds to the opening region of the communication hole of the support member so as to communicate the cavity and one opening of the communication hole. It is provided in the area of the adhesive.

Further, an invention relating to a thermal air flow meter for measuring the intake air amount of an internal combustion engine is known (Patent Document 2 below). Patent Document 2 discloses a resin package (claim 1, paragraph 0006) including a lead frame, a flow rate detecting element, a protective tape, and a sealing resin. The flow rate detecting element is mounted on one side of the lead frame. The protective tape is provided on the other side of the lead frame. The sealing resin seals the detection portion of the flow rate detecting element and a part of the protective tape so as to expose at least a part thereof.

Japanese Unexamined Patent Publication No. 2014-010023 Japanese Unexamined Patent Publication No. 2020-079711

In the conventional thermal air flow sensor described in Patent Document 1, for example, when the support member is a lead frame (Claim 6, First Example, FIGS. 1 and 2), the back surface side of the diaphragm is used. The cavity portion provided in the above communicates with the outside through the communication hole of the lead frame. In this case, for example, the vibration of the air due to the sound pressure from the turbocharger may propagate to the cavity through the communication hole of the lead frame, and the diaphragm may vibrate to reduce the measurement accuracy of the air flow rate.

On the other hand, in the conventional thermal air flow rate sensor described in Patent Document 1, for example, a substrate support member in which the support member is adhered and held on a lead frame (Claim 7, Second Example, FIG. 4 and In the case of FIG. 5), it is possible to prevent the vibration of the diaphragm as described above. However, there are problems such as an increase in the number of parts of the thermal air flow sensor and an increase in the size of the thermal air flow sensor.

Further, in the conventional thermal air flow meter described in Patent Document 1, by using the protective tape, it is possible to suppress an increase in the number of parts and an increase in size of the thermal air flow sensor. However, when the protective tape vibrates due to the sound pressure from the turbocharger, the diaphragm portion of the sensor chip vibrates, which may reduce the measurement accuracy of the air flow rate.

The present disclosure provides a physical quantity measuring device capable of suppressing a decrease in measurement accuracy of an air flow rate due to the influence of external sound pressure while suppressing an increase in the number of parts and an increase in the size of the device.

One aspect of the present disclosure is a lead frame, a resin encapsulation portion that partially seals the lead frame, a thermal flow sensor mounted on the surface of the lead frame, and an arrangement on the back surface of the lead frame. A physical quantity measuring device including a passage forming member, further including a damping member arranged between the thermal flow sensor and the lead frame, and the thermal flow sensor includes a semiconductor substrate and the semiconductor. A thin film portion formed on the front surface side of the substrate and exposed from the resin sealing portion, a flow rate detection portion provided on the front surface side of the thin film portion, and a back surface of the thin film portion formed on the back surface side of the semiconductor substrate. The lead frame has a recess adjacent to the side, and the lead frame has a through hole communicating with the opening of the recess and a ventilation groove formed along the back surface through the through hole. The passage forming member forms a ventilation passage that communicates the recess to the outside together with the through hole and the ventilation groove, and a portion that closes the through hole is exposed from the resin sealing portion. The physical quantity measuring device is characterized by having a plurality of communication holes set to an opening ratio such that the resistance coefficient to the gas flowing between the ventilation passage and the recess is less than 2.76.

According to the above aspect of the present disclosure, it is intended to provide a physical quantity measuring device capable of suppressing a decrease in measurement accuracy due to the influence of external sound pressure while suppressing an increase in the number of parts and an increase in size of the device. Can be done.

The system diagram which shows one Embodiment of the flow rate detection apparatus which concerns on this disclosure. The front view of the physical quantity measuring apparatus of FIG. The rear view of the physical quantity measuring apparatus of FIG. The left side view of the physical quantity measuring apparatus of FIG. The right side view of the physical quantity measuring apparatus of FIG. Top view of the physical quantity measuring device of FIG. The front view before arranging the sealing material of the physical quantity measuring apparatus of FIG. 2A. The rear view before attaching the cover of the physical quantity measuring apparatus of FIG. 2B. FIG. 3B is a cross-sectional view of the physical quantity measuring device along the line III (C) -III (C) of FIG. 3B. FIG. 2 is a cross-sectional view of the physical quantity measuring device along the line III (D) -III (D) of FIG. 2A. The front view of the circuit board of the physical quantity measuring apparatus of FIG. 3B. FIG. 4A is a cross-sectional view of a circuit board along the IV (B) -IV (B) line of FIG. 4A. The bottom view of the chip package mounted on the circuit board of FIG. 4A. Top view of the lead frame of the chip package shown in FIG. 4C. FIG. 4B is an enlarged view of the IV (E) part of the chip package mounted on the circuit board. The graph which shows the relationship between the resistance coefficient K and the attenuation factor A∞. The graph which shows the relationship between the diameter d and the pitch l of a communication hole, and the attenuation factor A∞. The graph which shows the relationship between the wire diameter d and pitch l of a mesh, and the attenuation factor A∞.

Hereinafter, embodiments of the physical quantity measuring device of the present invention will be described with reference to the drawings.

FIG. 1 is a system diagram showing an embodiment of the physical quantity measuring device according to the present disclosure. The physical quantity measuring device 100 of the present embodiment is used, for example, in an electronic fuel injection type internal combustion engine control system 1. The internal combustion engine control system 1 includes, for example, an internal combustion engine 10, a physical quantity measuring device 100, a throttle valve 25, a throttle angle sensor 26, an idle air control valve 27, an oxygen sensor 28, and a control device 4. There is.

The physical quantity measuring device 100 is used in a state of being inserted into the inside of the main passage 22 through a mounting hole provided in the passage wall of the intake body which is the main passage 22, and fixed to the passage wall of the main passage 22. The physical quantity measuring device 100 detects the physical quantity of the intake air, which is the gas to be measured 2 taken in through the air cleaner 21 and flows through the main passage 22, and outputs the physical quantity to the control device 4. The physical quantity measuring device 100 projects in the radial direction of the main passage 22 from the passage wall of the main passage 22 toward the center line 22a of the main passage 22 along the main flow direction of the gas to be measured 2 flowing through the main passage 22. That is, the protruding direction of the physical quantity measuring device 100 in the main passage 22 is, for example, a direction orthogonal to the center line 22a of the main passage 22.

The throttle valve 25 is built in, for example, the throttle body 23 arranged on the upstream side of the intake manifold 24 in the flow direction of the gas to be measured 2. The control device 4 changes, for example, the opening degree of the throttle valve 25 based on the operation amount of the accelerator pedal, and controls the flow rate of the intake air as the measured gas 2 flowing into the combustion chamber in the cylinder 11 of the internal combustion engine 10. do. The throttle angle sensor 26 measures the opening degree of the throttle valve 25 and outputs it to the control device 4. The idle air control valve 27 controls the amount of air bypassing the throttle valve 25.

The internal combustion engine 10 includes, for example, a cylinder 11, a piston 12, a spark plug 13, a fuel injection valve 14, an intake valve 15, an exhaust valve 16, and a rotation angle sensor 17. The intake air taken in through the air cleaner 21 based on the operation of the piston 12 of the internal combustion engine 10 flows through the main passage 22, and the flow rate is controlled by the throttle valve 25 in the throttle body 23. The intake air that has passed through the throttle body 23 passes through the intake manifold 24, further passes through the fuel injection valve 14 provided in the intake port, and flows into the combustion chamber in the cylinder 11 via the intake valve 15.

The control device 4 controls the fuel injection valve 14 based on the physical quantity of the intake air as the gas to be measured 2 input from the physical quantity measuring device 100, and injects fuel into the intake air. As a result, the intake air that has passed through the intake manifold 24 is mixed with the fuel injected from the fuel injection valve 14 and guided to the combustion chamber in the state of the air-fuel mixture. The control device 4 explosively burns the air-fuel mixture in the combustion chamber by the spark ignition of the spark plug 13, and generates mechanical energy in the internal combustion engine 10.

The rotation angle sensor 17 detects the position and state of the piston 12, the intake valve 15, and the exhaust valve 16 and information on the rotation speed of the internal combustion engine 10 and outputs the information to the control device 4. The gas generated by combustion is discharged from the combustion chamber of the cylinder 11 to the exhaust pipe through the exhaust valve 16, and is discharged from the exhaust pipe to the outside of the vehicle as exhaust gas 3. The oxygen sensor 28 is provided in the exhaust pipe, measures the oxygen concentration of the exhaust gas 3 flowing through the exhaust pipe, and outputs the oxygen concentration to the control device 4.

The control device 4 is based on the physical quantity of the intake air as the gas to be measured 2 flowing through the main passage 22 detected by the physical quantity measuring device 100, for example, flow rate, temperature, humidity, pressure, and the like, and each part of the internal combustion engine control system 1. To control. Specifically, when the control device 4 controls the opening degree of the throttle valve 25 based on the operation amount of the accelerator pedal, the flow rate of the intake air as the gas to be measured 2 flowing through the main passage 22 changes. The control device 4 controls the supply amount of fuel injected from the fuel injection valve 14 based on, for example, the flow rate of the gas to be measured 2 detected by the physical quantity measuring device 100. As a result, the mechanical energy generated by the internal combustion engine 10 is controlled.

The control device 4 calculates the fuel injection amount and the ignition timing based on the physical quantity of the intake air which is the output of the physical quantity measuring device 100 and the rotation speed of the internal combustion engine 10 measured based on the output of the rotation angle sensor 17. do. Based on these calculation results, the control device 4 controls the fuel injection amount by the fuel injection valve 14 and the ignition timing of the spark plug 13.

The control device 4 actually further fuels the fuel based on the temperature of the gas to be measured 2, the change state of the opening degree of the throttle valve 25, the change state of the rotation speed of the internal combustion engine 10, and the air-fuel ratio state of the exhaust gas 3. The supply amount and ignition timing are finely controlled. Further, the control device 4 controls the amount of air bypassing the throttle valve 25 by the idle air control valve 27 in the idle operation state of the internal combustion engine 10, and controls the rotation speed of the internal combustion engine 10 in the idle operation state.

The fuel supply amount and ignition timing, which are the main control amounts of the internal combustion engine 10, are both calculated using the output of the physical quantity measuring device 100 as the main parameter. Therefore, it is important to improve the measurement accuracy of the physical quantity measuring device 100, suppress the change with time, and improve the reliability in order to improve the control accuracy and the reliability of the vehicle.

Especially in recent years, there has been a very high demand for fuel efficiency of vehicles, and a very high demand for exhaust gas purification. In order to meet these demands, it is extremely important to improve the detection accuracy of the physical quantity of the intake air detected by the physical quantity measuring device 100. It is also important that the physical quantity measuring device 100 maintains high reliability.

The vehicle equipped with the physical quantity measuring device 100 is used in an environment where changes in temperature and humidity are large. It is desirable that the physical quantity measuring device 100 also considers the response to changes in temperature and humidity in the usage environment and the response to dust and pollutants.

Further, the physical quantity measuring device 100 is attached to the intake pipe affected by the heat generated from the internal combustion engine. Therefore, the heat generated by the internal combustion engine is transmitted to the physical quantity measuring device 100 via the intake pipe. Since the physical quantity measuring device 100 detects the flow rate of the measured gas 2 by conducting heat transfer with the measured gas 2, it is important to suppress the influence of heat from the outside as much as possible.

Hereinafter, the physical quantity measuring device 100 of the present embodiment will be described in more detail with reference to FIGS. 2A to 2E, FIGS. 3A to 3D, and FIGS. 4A to 4E. In each of these figures, the X-axis parallel to the protruding direction of the physical quantity measuring device 100 in the main passage 22 shown in FIG. 1, the Y-axis parallel to the center line 22a of the main passage 22, and the thickness of the physical quantity measuring device 100. A Cartesian coordinate system consisting of Z axes parallel to the direction is shown. In the following description, it is assumed that the gas to be measured 2 flows along the center line 22a (Y-axis) of the main passage 22.

2A to 2E are a front view, a rear view, a left side view, a right side view, and a top view of the physical quantity measuring device 100 of FIG. 1, respectively. The physical quantity measuring device 100 includes, for example, a housing 110 and a cover 120.

The housing 110 is manufactured, for example, by injection molding a synthetic resin material. The cover 120 is, for example, a plate-shaped member made of metal or synthetic resin. As the cover 120, for example, a molded product made of a synthetic resin material can be used. The housing 110 and the cover 120 constitute a housing of the physical quantity measuring device 100 arranged in the main passage 22.

The housing 110 has, for example, a flange 111, a connector 112, and a measuring unit 113.

As shown in FIG. 2E, the flange 111 has a substantially rectangular plate-like shape, and has a pair of fixing portions 111a at diagonal corners. The fixing portion 111a has a cylindrical through hole 111b in the center portion through which the flange 111 is inserted and through which the fixing screw is inserted. In order to fix the physical quantity measuring device 100 to the main passage 22, the measuring unit 113 is inserted into the mounting hole provided in the main passage 22. Then, the fixing screw inserted through the through hole 111b of the flange 111 is screwed into the screw hole of the main passage 22 to fix the flange 111 to the passage wall of the main passage 22. As a result, the physical quantity measuring device 100 is fixed to the main passage 22 which is an intake body.

The connector 112 protrudes from the flange 111, is arranged outside the main passage 22 which is an intake body, and is connected to an external device. As shown in FIG. 2D, a plurality of external terminals 112a and correction terminals 112b are provided inside the connector 112. The external terminal 112a includes, for example, an output terminal for a physical quantity such as a flow rate and a temperature, which is a measurement result of the physical quantity measuring device 100, and a power supply terminal for supplying DC power for operating the physical quantity measuring device 100.

The correction terminal 112b measures the physical quantity after the physical quantity measuring device 100 is manufactured, obtains a correction value for each physical quantity measuring device 100, and is used to store the correction value in the internal memory of the physical quantity measuring device 100. In the subsequent measurement of the physical quantity by the physical quantity measuring device 100, the correction data based on the correction value stored in the memory is used, and the correction terminal 112b is not used.

The measuring unit 113 extends from the flange 111 fixed to the passage wall of the main passage 22 toward the center line 22a of the main passage 22 so as to project in the radial direction of the main passage 22 orthogonal to the center line 22a. The measuring unit 113 has a flat rectangular parallelepiped shape. The measuring unit 113 has a length in the protruding direction (X-axis direction) of the measuring unit 113 in the main passage 22 and a width in the main flow direction (Y-axis direction) of the gas to be measured 2 in the main passage 22. There is. Further, the measuring unit 113 has a thickness in a direction (Z-axis direction) orthogonal to the protruding direction (X-axis direction) and the main flow direction (Y-axis direction) of the gas to be measured 2. As described above, since the measurement unit 113 has a flat shape along the main flow direction of the gas to be measured 2, the fluid resistance to the gas to be measured 2 can be reduced.

The measuring unit 113 has a front surface 113a, a back surface 113b, an upstream side surface 113c, a downstream side surface 113d, and a lower surface 113e. The front surface 113a and the back surface 113b have a larger area than the other surfaces of the measuring unit 113, and are substantially parallel to the protruding direction (X-axis direction) of the measuring unit 113 and the center line 22a (Y-axis direction) of the main passage 22. The upstream side surface 113c and the downstream side surface 113d have an elongated shape having a smaller area than the front surface 113a and the back surface 113b, and are substantially orthogonal to the center line 22a (Y-axis direction) of the main passage 22. The lower surface 113e has a smaller area than the other surfaces of the measuring unit 113, is substantially parallel to the center line 22a (Y-axis direction) of the main passage 22, and is approximately orthogonal to the protruding direction (X-axis direction) of the measuring unit 113. ..

The measuring unit 113 has a sub-passage inlet 114 on the upstream side surface 113c and a first outlet 115 and a second outlet 116 on the downstream side surface 113d. The sub-passage inlet 114, the first outlet 115, and the second outlet 116 are provided at the tip of the measuring unit 113 on the tip side of the center in the protruding direction (X-axis direction) of the measuring unit 113. As a result, the gas to be measured 2 near the central portion of the main passage 22 away from the inner wall surface of the main passage 22 can be taken in from the sub-passage inlet 114. Therefore, the physical quantity measuring device 100 can suppress a decrease in measurement accuracy due to the influence of heat of the internal combustion engine 10.

FIG. 3A is a front view before arranging the sealing material 119 of the physical quantity measuring device 100 of FIG. 2A. FIG. 3B is a rear view of the physical quantity measuring device 100 of FIG. 1 before attaching the cover 120. FIG. 3C is a cross-sectional view of the physical quantity measuring device 100 along the line III (C) -III (C) of FIG. 3B. FIG. 3D is a cross-sectional view of the physical quantity measuring device 100 along the line III (D) -III (D) of FIG. 2A.

The external terminal 112a of the connector 112 shown in FIG. 2D is connected to the pad of the circuit board 140 via the bonding wire 143, for example, as shown in FIG. 3A. In the circuit board 140, for example, the protection circuit 144 is mounted on the surface to which the bonding wire 143 is connected. The protection circuit 144 stabilizes the voltage in the circuit and eliminates noise. The bonding wire 143 and the protection circuit 144 are covered and sealed by the encapsulant 119 as shown in FIG. 2A. As the encapsulant 119, for example, a silicone gel or an epoxy-based encapsulant having higher rigidity than the silicone-based encapsulant can be used.

As shown in FIG. 3B, the housing 110 has a concave sub-passage groove 117 and a concave circuit chamber 118 on the back surface 113b side of the measuring unit 113. As shown in FIG. 3D, the sub-passage groove 117 forms the sub-passage 130 together with the cover 120 by closing the opening by the cover 120. The sub-passage 130 takes in the gas to be measured 2 flowing through the main passage 22 and detours it. As shown in FIG. 3B, for example, the gas to be measured 2 flowing through the main passage 22 is taken into the sub-passage 130 from the sub-passage inlet 114 that opens on the side surface 113c on the upstream side of the measuring unit 113.

The sub-passage groove 117 has, for example, a first sub-passage groove 117a and a second sub-passage groove 117b. As shown in FIG. 3B, the first sub-passage groove 117a extends from the sub-passage inlet 114 opening on the upstream side surface 113c of the measuring unit 113 to the first outlet 115 opening on the downstream side surface 113d of the measuring unit 113. , Extends along the center line 22a (Y-axis direction) of the main passage 22. The first sub-passage groove 117a forms the first sub-passage 131 with the cover 120, for example, as shown in FIG. 3D. The first sub-passage 131 returns the gas to be measured 2 taken in from the sub-passage inlet 114 from the first outlet 115 to the main passage 22.

As shown in FIG. 3B, the second sub-passage groove 117b branches from the middle of the first sub-passage groove 117a and extends toward the flange 111 along the projecting direction (X-axis direction) of the measuring unit 113. .. Further, the second sub-passage groove 117b is curved in a U shape so as to be folded back in the opposite direction, and extends toward the tip end portion of the measuring unit 113 along the protruding direction (X-axis direction) of the measuring unit 113. The second sub-passage groove 117b curves in the direction along the center line 22a (Y-axis direction) of the main passage 22 at the tip of the measuring unit 113, and opens to the side surface 113d on the downstream side of the measuring unit 113. It is connected to 116. For example, as shown in FIG. 3C, the second sub-passage groove 117b has an opening closed by the cover 120 to form a second sub-passage 132 with the cover 120. The sub-passage 130 includes a first sub-passage 131 and a second sub-passage 132.

The circuit chamber 118 is provided in a concave shape on the back surface 113b side of the measurement unit 113 of the housing 110 and on the base end side of the measurement unit 113 connected to the flange 111, and accommodates the circuit board 140. The circuit chamber 118 is a second sub-passage in the main flow direction (Y-axis direction) of the gas to be measured 2 flowing through the main passage 22 on the base end side of the measurement unit 113 with respect to the first sub-passage groove 117a of the sub-passage groove 117. It is provided adjacent to the upstream side of the groove 117b.

FIG. 4A is a front view of the circuit board 140 of the physical quantity measuring device 100 of FIG. 3B. FIG. 4B is a cross-sectional view of the circuit board 140 along the IV (B) -IV (B) line of FIG. 4A. 4C is a bottom view of the chip package 150 mounted on the circuit board 140 of FIG. 4A. FIG. 4D is a plan view of the lead frame 154 of the chip package 150 shown in FIG. 4C. FIG. 4E is an enlarged view of the IV (E) portion of the chip package 150 mounted on the circuit board 140 of FIG. 4B.

As shown in FIG. 4B, the chip package 150 includes a lead frame 154, a resin sealing portion 155 that partially seals the lead frame 154, and a thermal flow sensor 151 mounted on the surface of the lead frame 154. , Equipped with. Further, the chip package 150 further includes, for example, a passage forming member 156 arranged on the back surface of the lead frame 154 and a damping member 157 arranged between the thermal flow rate sensor 151 and the lead frame 154.

The chip package 150 has a configuration in which the thermal flow sensor 151 and the electronic component 152 are integrally sealed by, for example, a resin sealing portion 155 formed by a transfer mold of a thermosetting resin. As shown in FIG. 4A, the connection terminal 153 of the chip package 150 is mounted on the circuit board 140 via a bonding material such as solder. As shown in FIG. 3B, the connection terminal 153 is sealed by the curable sealing material 141.

The connection terminal 153 of the chip package 150 is connected to, for example, the electronic component 152 shown in FIGS. 4B and 4D. The chip package 150 drives the thermal flow sensor 151 by, for example, an electronic component 152. The electronic component 152 is, for example, an LSI, which is connected to the thermal flow rate sensor 151 via a bonding wire to drive the thermal flow rate sensor 151.

As shown in FIG. 4E, the thermal flow sensor 151 has a semiconductor substrate 151a and a thin film portion 151d formed on the surface side of the semiconductor substrate 151a and exposed from the resin sealing portion 155. Further, the thermal flow rate sensor 151 has a flow rate detection unit 151b provided on the front surface side of the thin film portion 151d, and a recess 151c formed on the back surface side of the semiconductor substrate 151a and adjacent to the back surface side of the thin film portion 151d. is doing.

Although not shown, the flow rate detection unit 151b includes, for example, a pair of temperature sensors arranged on the upstream side and the downstream side in the flow direction of the gas to be measured 2, and a heater arranged between the pair of temperature sensors. I have. The thermal flow rate sensor 151 measures the flow rate of the gas to be measured 2 by detecting the temperature difference by, for example, a pair of temperature sensors of the flow rate detection unit 151b. The opening of the recess 151c has, for example, a square shape having a length and width of about 1 [mm] × 1 [mm].

As shown in FIGS. 4B and 4C, for example, the thermal flow rate sensor 151 measures the flow rate of the gas to be measured 2 flowing through the measurement passage 132a formed between the circuit board 140 and the concave groove 150c of the chip package 150. do. The measurement passage 132a is formed, for example, in the second sub-passage groove 117b of the sub-passage groove 117, that is, in the second sub-passage 132 of the sub-passage 130, as shown in FIGS. 3B and 3D.

As shown in FIGS. 4D and 4E, the lead frame 154 is formed along a through hole 154a communicating with the opening of the recess 151c of the semiconductor substrate 151a and communicating with the through hole 154a along the back surface of the lead frame 154. It has a ventilation groove 154b and. Here, the back surface of the lead frame 154 is the surface opposite to the front surface of the lead frame 154 on which the thermal flow sensor 151 and the electronic component 152 are mounted. The through hole 154a is formed, for example, in a shape and size substantially equal to the opening of the recess 151c.

Further, the lead frame 154 has, for example, a through hole 154c communicating with the other end of the ventilation groove 154b opposite to one end of the ventilation groove 154b communicating with the through hole 154a of the lead frame 154. As shown in FIG. 4B, the through hole 154c is exposed from the resin sealing portion 155 and communicates with the circuit chamber 118. In the example shown in FIG. 4D, three ventilation grooves 154b are formed on the back surface of the lead frame 154. The number of ventilation grooves 154b is not particularly limited, and may be a single number or a plurality of two or four or more.

As shown in FIG. 4B, the passage forming member 156 is arranged on the back surface of the lead frame 154. The passage forming member 156 is, for example, a film-like adhesive tape provided with an adhesive layer on the surface of a resin base material, and is adhered to the back surface of the lead frame 154 via the adhesive layer. As the base material, for example, a film-shaped polyimide can be used. Further, as the pressure-sensitive adhesive layer, for example, an acrylic-based or silicone-based pressure-sensitive adhesive can be used. That is, the passage forming member 156 is, for example, a polyimide tape.

As shown in FIGS. 4D and 4E, the passage forming member 156 forms a ventilation passage 158 for communicating the recess 151c of the semiconductor substrate 151a to the outside together with the through hole 154a and the through hole 154c and the ventilation groove 154b of the lead frame 154. ing. Further, in the passage forming member 156, a portion of the lead frame 154 that closes the through hole 154a and the through hole 154c is exposed from the resin sealing portion 155.

As shown in FIG. 4E, the damping member 157 is arranged between the thermal flow rate sensor 151 and the lead frame 154. The damping member 157 is, for example, an adhesive sheet for adhering the thermal flow sensor 151 to the lead frame 154. In this case, as the base material of the adhesive sheet constituting the damping member 157, for example, a film-shaped polyolefin or a film-shaped polyolefin in which epoxy powder is dispersed in a sea-island shape can be used. Further, for the adhesive layer of the adhesive sheet constituting the damping member 157, for example, a silicone-based or polyurethane-based adhesive can be used.

More specifically, as the damping member 157, for example, a die bonding film manufactured by Hitachi Kasei Co., Ltd., HR-9004, HR-9050G, or the like is suitable. The thickness of the adhesive sheet constituting the damping member 157 is, for example, about 15 [μm] or 30 [μm]. Further, the elastic modulus of the adhesive sheet constituting the damping member 157 is, for example, 1 [MPa] or more due to high temperature aging. The damping member 157 is not limited to the configuration in which the entire damping member 157 is an adhesive sheet.

More specifically, in the damping member 157, at least a portion arranged between the through hole 154a of the lead frame 154 and the recess 151c of the semiconductor substrate 151a of the thermal flow sensor 151 may be a mesh. In this case, a metal mesh can be used as the damping member 157. Further, the damping member 157 is located outside the through hole 154a of the lead frame 154, that is, a portion other than the mesh, that is, a portion arranged between the thermal flow rate sensor 151 and the lead frame 154 is formed by an adhesive sheet. It may be configured.

The damping member 157 has a plurality of communication holes 157a set to an opening ratio such that the resistance coefficient to the gas flowing between the ventilation passage 158 and the recess 151c of the thermal flow sensor 151 is less than 2.76. .. For example, assuming that the drag coefficient for the gas flowing between the ventilation passage 158 and the recess 151c of the thermal flow sensor 151 is K and the opening ratio of the plurality of communication holes 157a is β, the following equation (1) is established.

K = 0.85 (1-β) / β ² ... (1)

The opening ratio β of the plurality of communication holes 157a is the opening area of the plurality of communication holes 157a with respect to the area of the damping member 157 arranged between the through hole 154a of the lead frame 154 and the recess 151c of the thermal flow sensor 151. Is the ratio of. More specifically, as shown in FIG. 4D, the plurality of communication holes 157a of the damping member 157 are arranged in a staggered manner in the opening region of the through hole 154a of the lead frame 154, for example. In this case, the opening ratio β of the plurality of communication holes 157a can be expressed by the following equation (2), where d is the diameter of the communication holes 157a and l is the pitch.

β = {π / (2 × 3 ^1/2 )} × (d / l) ² ... (2)

Further, in the damping member 157, when at least the portion arranged in the opening region of the through hole 154a of the lead frame 154 is a mesh, the opening ratio β of the plurality of communication holes 157a has a wire diameter of d and a pitch of l. It can be expressed by the following equation (3).

β = (1-d / l) ² ... (3)

As described above, the physical quantity measuring device 100 of the present embodiment sets the opening ratio β of the plurality of communication holes 157a of the damping member 157, for example, to heat the measured gas 2 at a frequency in a predetermined range due to vibration. The error of the signal of the formula flow sensor 151 is set to a predetermined value or less. More specifically, for example, the sound pressure of the turbocharger provided in the internal combustion engine control system 1 causes the gas to be measured 2 to vibrate at a frequency of 10 [kHz] or more and 20 [kHz] or less.

As described above, the physical quantity measuring device 100 of the present embodiment has the opening ratio β of the plurality of communication holes 157a of the damping member 157 with respect to the gas flowing between the ventilation passage 158 and the recess 151c of the thermal flow sensor 151. The aperture ratio β is set so that the resistance coefficient K is less than 2.76. As a result, in the physical quantity measuring device 100 of the present embodiment, the error of the signal of the thermal flow sensor 151 with respect to the vibration of the gas to be measured 2 having a frequency of 10 [kHz] or more and 20 [kHz] or less becomes 150 [db] or less. It has become.

Hereinafter, the operation of the physical quantity measuring device 100 of the present embodiment will be described.

In the internal combustion engine control system 1 as shown in FIG. 1, for example, the measured gas 2 taken into the sub-passage 130 of the physical quantity measuring device 100 by the sound pressure generated by the turbocharger mounted on the vehicle has a predetermined frequency. It may vibrate. In this case, for example, as shown in FIG. 4B, the passage forming member 156 exposed from the resin sealing portion 155 of the chip package 150 vibrates at the portion of the lead frame 154 facing the through hole 154a.

Here, when the damping member 157 is not arranged between the through hole 154a of the lead frame 154 and the recess 151c of the semiconductor substrate 151a of the thermal flow sensor 151, the through hole 154a is caused by the vibration of the passage forming member 156. The air flowing between the recesses 151c vibrates. As a result, the thin film portion 151d of the semiconductor substrate 151a vibrates, and the measurement accuracy of the flow rate of the gas to be measured 2 by the thermal flow rate sensor 151 is lowered.

On the other hand, the physical quantity measuring device 100 of the present embodiment is mounted on the surface of the lead frame 154, the resin sealing portion 155 that partially seals the lead frame 154, and the lead frame 154, as described above. A thermal flow sensor 151 and a passage forming member 156 arranged on the back surface of the lead frame 154 are provided. Further, the physical quantity measuring device 100 of the present embodiment further includes a damping member 157 arranged between the thermal flow rate sensor 151 and the lead frame 154. The thermal flow sensor 151 includes a semiconductor substrate 151a, a thin film portion 151d formed on the surface side of the semiconductor substrate 151a and exposed from the resin sealing portion 155, and a flow rate detection unit provided on the surface side of the thin film portion 151d. It has 151b and a recess 151c formed on the back surface side of the semiconductor substrate 151a and adjacent to the back surface side of the thin film portion 151d. The lead frame 154 has a through hole 154a communicating with the opening of the recess 151c and a ventilation groove 154b communicating with the through hole 154a and formed along the back surface of the lead frame 154. The passage forming member 156 forms a ventilation passage 158 that communicates the recess 151c to the outside together with the through hole 154a and the ventilation groove 154b, and the portion that closes the through hole 154a is exposed from the resin sealing portion 155. The damping member 157 has a plurality of communication holes 157a set to an opening ratio β such that the drag coefficient K against the gas flowing between the ventilation passage 158 and the recess 151c is less than 2.76.

With this configuration, when the passage forming member 156 exposed from the resin sealing portion 155 of the chip package 150 vibrates, the through hole 154a of the lead frame 154 and the recess 151c of the semiconductor substrate 151a are formed through the plurality of communication holes 157a of the damping member 157. Air circulates between them. Here, the opening ratio β of the plurality of communication holes 157a of the damping member 157 is such that the drag coefficient K against the gas flowing between the through holes 154a constituting the ventilation passage 158 and the recess 151c is less than 2.76. It is set.

FIG. 5A is a graph showing the relationship between the drag coefficient K and the attenuation factor A∞. As shown in FIG. 5A, when the drag coefficient K is less than 2.76, the damping factor A∞ becomes larger than zero, and the vibration of the gas flowing between the through hole 154a constituting the ventilation passage 158 and the recess 151c is generated. Decay. Therefore, as described above, by setting the opening ratio β of the plurality of communication holes 157a of the damping member 157 so that the drag coefficient K is less than 2.76, the air flows between the ventilation passage 158 and the recess 151c. It is possible to attenuate the vibration of the gas. The aperture ratio β can be obtained by, for example, the above-mentioned equation (2) or (3), and the attenuation factor A∞ can be obtained by the following equations (4) to (6) with α and C as proportional constants. Can be asked.

A∞ = (1 + α-αK) / (1 + α + K) ・・・ (4)
α = 1.1 × (1 + K) ^1/2 ... (5)
K = C (1-β) / β ² ... (6)

FIG. 5B is a graph showing the relationship between the diameter d and pitch l of the communication holes 157a and the attenuation factor A∞. In FIG. 5B, the arrangement of the plurality of communication holes 157a of the damping member 157 is a staggered arrangement as shown in FIG. 4D. The opening ratio β of the plurality of communication holes 157a of the damping member 157 is determined by the diameter d and the pitch l of the communication holes 157a as shown in the above equation (2). For example, as described above, it is assumed that the opening of the recess 151c of the thermal flow sensor 151 and the through hole 154a of the lead frame 154 are squares of 1 [mm] × 1 [mm]. In this case, the diameter d and pitch l of the communication hole 157a of the damping member 157 arranged between the opening of the recess 151c of the thermal flow sensor 151 and the through hole 154a of the lead frame 154, and the damping factor A∞. The relationship shown in FIG. 5B is established between the two.

That is, when the diameter d of the communication hole 157a is 20 [μm], the attenuation factor A∞ is set to be larger than 0 by setting the pitch l in the range of about 30 [μm] to about 50 [μm]. Can be done. When the diameter d of the communication hole 157a is 50 [μm], the damping factor A∞ is set to be larger than 0 by setting the pitch l in the range of about 80 [μm] to about 110 [μm]. Can be done. When the diameter d of the communication hole 157a is 100 [μm], the damping factor A∞ is set to be larger than 0 by setting the pitch l in the range of about 170 [μm] to about 230 [μm]. Can be done. When the diameter d of the communication hole 157a is 200 [μm], the damping factor A∞ is set to be larger than 0 by setting the pitch l in the range of about 330 [μm] to about 460 [μm]. Can be done. When the communication hole 157a is formed by laser processing, it is possible to suppress the generation of burrs by setting the diameter d to about 100 [μm].

FIG. 5C is a graph showing the relationship between the wire diameter d and the pitch l of the mesh constituting the damping member 157 and the damping factor A∞. The opening ratio β of the plurality of communication holes 157a of the damping member 157 is determined by the wire diameter d and the pitch l of the mesh constituting the communication holes 157a, as shown in the above equation (3). For example, as described above, it is assumed that the opening of the recess 151c of the thermal flow sensor 151 and the through hole 154a of the lead frame 154 are squares of 1 [mm] × 1 [mm]. In this case, between the wire diameter d and pitch l of the mesh arranged between the opening of the recess 151c of the thermal flow sensor 151 and the through hole 154a of the lead frame 154, and the damping factor A∞, The relationship shown in FIG. 5C is established.

That is, when the wire diameter d of the mesh constituting the damping member 157 is 20 [μm], the damping factor A∞ is set to 0 by setting the pitch l in the range of about 70 [μm] to about 200 [μm]. Can be larger. Further, when the wire diameter d of the mesh is 50 [μm], the attenuation factor A∞ can be made larger than 0 by setting the pitch l in the range of about 180 [μm] to about 500 [μm]. can. Further, when the wire diameter d of the mesh is 100 [μm], the attenuation factor A∞ can be made larger than 0 by setting the pitch l in the range of about 360 [μm] to about 1000 [μm]. can. By setting the wire diameter d of the mesh to 20 [μm] and the pitch l to the range of about 100 [μm] to about 200 [μm], the damping effect of air vibration is high and the damping member 157 is manufactured. Can be facilitated.

As described above, according to the physical quantity measuring device 100 of the present embodiment, by using the passage forming member 156, the substrate is supported like the conventional thermal air flow rate sensor described in the second embodiment of Patent Document 1. There is no need to use members, and it is possible to suppress an increase in the number of parts and an increase in the size of the device. Further, according to the physical quantity measuring device 100 of the present embodiment, the vibration of the air flowing between the ventilation passage 158 and the recess 151c of the thermal flow sensor 151 is attenuated by the plurality of communication holes 157a of the damping member 157. It is possible to suppress a decrease in the measurement accuracy of the air flow rate due to the influence of sound pressure from the outside.

Further, in the physical quantity measuring device 100 of the present embodiment, the damping member 157 is, for example, an adhesive sheet for adhering the thermal flow rate sensor 151 to the lead frame 154. With this configuration, the adhesive sheet conventionally used for adhering the thermal flow sensor 151 to the lead frame 154 can be used as the damping member 157. Therefore, it is possible to suppress an increase in the number of parts of the physical quantity measuring device 100 and an increase in the size of the device. In addition, the damping member 157 can be easily installed and processed.

Further, in the physical quantity measuring device 100 of the present embodiment, the elastic modulus of the adhesive sheet used as the damping member 157 is, for example, 1 [MPa] or more. With this configuration, the deflection of the damping member 157 due to the air flowing between the ventilation passage 158 and the recess 151c of the thermal flow sensor 151 is prevented, and the vibration of the air passing through the communication hole 157a is more reliably damped. Will be possible.

Further, in the physical quantity measuring device 100 of the present embodiment, the damping member 157 is, for example, a mesh. With this configuration, the strength and durability of the damping member 157 can be improved. For example, when the material of the mesh constituting the damping member 157 is the same as the material of the lead frame 154, the linear expansion coefficients of the mesh constituting the damping member 157 and the lead frame 154 become equal to each other, and the generation of thermal stress is suppressed. be able to. Further, it is possible to simplify the manufacturing process by omitting the drilling process for the damping member 157.

Further, in the physical quantity measuring device 100 of the present embodiment, the resistance coefficient to the air flowing between the ventilation passage 158 and the recess 151c of the thermal flow sensor 151 is K, and the opening ratio of the plurality of communication holes 157a is β. Equation (1): K = 0.85 (1-β) / β ² is established. Thereby, the opening ratio β of the plurality of communication holes 157a can be determined based on the drag coefficient K.

Further, in the physical quantity measuring device 100 of the present embodiment, the error of the signal of the thermal flow sensor 151 with respect to the vibration of the gas having a frequency of 10 [kHz] or more and 20 [kHz] or less is 150 [db] or less. With this configuration, it becomes possible to improve the measurement accuracy of the flow rate of the gas to be measured 2 by the thermal flow rate sensor 151.

Although the embodiment of the physical quantity measuring device according to the present disclosure has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and the design change is not deviated from the gist of the present disclosure. Etc., but they are included in this disclosure. As the passage forming member, a glass sheet having a low melting point that reaches a softening point at about 300 [° C.] to 350 [° C.] may be used. In this case, the glass sheet is integrated with the lead frame by chemically bonding the flux, Ni, Au, and other metals blended in the glass sheet. In this case, a plurality of communication holes are formed in the adhesive sheet for adhering the thermal flow sensor and the lead frame by forming an opening having the same shape and size as the through hole of the lead frame or the opening of the recess of the thermal flow sensor. The damping member to have may be omitted.

100 Physical quantity measuring device 151 Thermal flow sensor 151a Semiconductor substrate 151b Flow detection part 151c Recessed part 151d Thin film part 154 Lead frame 154a Through hole 154b Ventilation groove 155 Resin sealing part 156 Passage forming member 157 Damping member (adhesive sheet, mesh)
157a Communication hole 158 Ventilation passage K Drag coefficient β Aperture ratio

Claims

A lead frame, a resin sealing portion that partially seals the lead frame, a thermal flow rate sensor mounted on the surface of the lead frame, and a passage forming member arranged on the back surface of the lead frame. It is a physical quantity measuring device equipped
A damping member arranged between the thermal flow sensor and the lead frame is further provided, and the thermal flow sensor is formed on the semiconductor substrate and the surface side of the semiconductor substrate and exposed from the resin sealing portion. It has a thin film portion, a flow rate detecting portion provided on the front surface side of the thin film portion, and a recess formed on the back surface side of the semiconductor substrate and adjacent to the back surface side of the thin film portion.
The lead frame has a through hole communicating with the opening of the recess and a ventilation groove communicating with the through hole and formed along the back surface.
The passage forming member forms a ventilation passage that allows the recess to communicate with the outside together with the through hole and the ventilation groove, and a portion that closes the through hole is exposed from the resin sealing portion. , A physical quantity measuring device having a plurality of communication holes set to an opening ratio such that a drag coefficient against a gas flowing between the ventilation passage and the recess is less than 2.76.
The physical quantity measuring device according to claim 1, wherein the damping member is an adhesive sheet for adhering the thermal flow sensor to the lead frame.
The physical quantity measuring device according to claim 2, wherein the elastic modulus of the adhesive sheet is 1 [MPa] or more.
The physical quantity measuring device according to claim 1, wherein the damping member is a mesh.
Let K be the drag coefficient and β be the aperture ratio.
Equation: K = 0.85 (1-β) / β 2
The physical quantity measuring device according to claim 1, wherein the above is satisfied.
The physical quantity measuring device according to claim 1, wherein the error of the signal of the thermal flow sensor with respect to the vibration of the gas having a frequency of 10 [kHz] or more and 20 [kHz] or less is 150 [db] or less. ..