JP2021032845A - Sensor device - Google Patents

Abstract

To provide a sensor device that has a structure capable of reducing an influence of mounting variation such as the thickness variation of a circuit board on the positioning accuracy of a sensor element in a channel.SOLUTION: A sensor device includes a detecting portion that has a sensor element installed in a passage to detect physical amount related to gas passing through the passage, a circuit board electrically connected to the detecting portion, a fixing member that fixes the circuit board and the detecting portion respectively, and a passage forming portion. The passage forming portion has a first pat to which the fixing member is fixed, a second part opposing to the circuit board via a gap, and a third part that is one of surfaces forming the passage and opposes to the sensor element via the passage, on the same surface.SELECTED DRAWING: Figure 2

Description

The present invention relates to a sensor device.

An internal combustion engine such as an automobile is provided with an electronically controlled fuel injection device for efficiently operating the internal combustion engine by appropriately adjusting the amounts of air and fuel flowing into the internal combustion engine. The electronically controlled fuel injection device is provided with a flow rate sensor for measuring the flow rate of air flowing into the internal combustion engine. A flow rate sensor in which a diaphragm is formed on a silicon element by using micromachining technology and a flow rate sensor element having a flow rate detection unit provided on the diaphragm is mounted is attracting attention.

The flow rate detection unit includes a heat generation resistor and a resistance temperature detector, and measures the flow rate under the control of a control circuit unit provided on the same or different semiconductor chips. Such a flow rate sensor has, for example, a structure in which the flow rate detection unit is exposed and the periphery of the semiconductor chip is sealed with a resin. Instead of sealing with resin, a flow sensor chip pre-packaged with a resin mold is known. Further, there is a technique related to the semiconductor module described in Patent Document 1.

JP-A-2018-81959

For example, if mounting variations such as circuit board thickness variations affect the positioning accuracy of the sensor element in the flow path, the flow rate measurement accuracy varies. Therefore, we provide a sensor device having a structure capable of reducing the influence of mounting variations such as thickness variations of the circuit board on the positioning accuracy of the sensor element in the flow path.

In order to solve the above problems, the sensor device according to one aspect of the present invention is electrically connected to a detection unit having a sensor element installed in the passage and detecting a physical quantity related to a gas passing through the passage, and the detection unit. A circuit board, a fixing member for fixing the circuit board and the detection unit, and a passage forming unit are provided. The passage forming portion is one of the surfaces forming the passage, the first portion to which the fixing member is fixed, the second portion facing the circuit board via the gap, and the third portion facing the sensor element via the passage. The portion and the portion are on the same surface.

According to the present invention, it is possible to provide a sensor device having a structure capable of reducing the influence of mounting variations such as thickness variations of a circuit board on the positioning accuracy of sensor elements in a flow path. Issues, configurations and effects other than those described above will be clarified by the description of the following embodiments.

It is a top view of the flow rate sensor module which concerns on Example 1. FIG. It is sectional drawing of AA in the flow rate sensor module of FIG. It is a top view which shows a part of the structure of the flow rate sensor module of FIG. It is sectional drawing BB in the flow rate sensor module of FIG. FIG. 3 is a cross-sectional view taken along the line CC of the flow rate sensor module of FIG. It is sectional drawing BB in FIG. 3 about the flow rate sensor module which is the modification of Example 1. FIG. It is a top view which shows a part of the structure of the flow rate sensor module which is another modification of Example 1. FIG. It is a top view which shows a part of the structure of the flow rate sensor module which concerns on Example 2. FIG. It is a DD cross-sectional view of the flow rate sensor module of FIG. It is a top view which shows a part of the structure of the flow rate sensor module which concerns on Example 3. FIG. It is sectional drawing of EE in the flow rate sensor module of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The examples are examples for explaining the present invention, and are appropriately omitted and simplified for the purpose of clarifying the description. The present invention can also be implemented in various other forms. Unless otherwise specified, each component may be singular or plural. The positions, sizes, shapes, ranges, etc. of each component shown in the drawings may not represent the actual positions, sizes, shapes, ranges, etc., in order to facilitate understanding of the invention. Therefore, the present invention is not necessarily limited to the position, size, shape, range and the like disclosed in the drawings. When there are a plurality of components having the same or similar functions, they may be described by adding different subscripts to the same reference numerals. Further, when it is not necessary to distinguish between these a plurality of components, the subscripts may be omitted for explanation. Further, the three-dimensional coordinate axes of the X-axis, the Y-axis, and the Z-axis are shown in the lower right of each figure. Among the drawings illustrating the same embodiment, it is understood that the relationship between these three axes (X-axis, Y-axis, and Z-axis) and the configuration example of the embodiment (for example, the flow rate sensor module) is the same. Good.

FIG. 1 is a plan view of the flow rate sensor module 1 according to the first embodiment. However, in FIG. 1, the cover 4 of the flow rate sensor module 1 is not shown. FIG. 2 is a cross-sectional view taken along the line AA of the flow rate sensor module 1 of FIG. FIG. 2 also shows the cover 4 of the flow rate sensor module 1.

The flow rate sensor module 1 includes various sensors including a flow rate sensor chip 5, a circuit board 9 on which various sensors and the like are mounted, a housing 2, a base member 3, a cover 4, and a support member 8. The circuit board 9 includes a flow rate sensor chip 5, a pressure sensor chip 6, a humidity sensor chip 7, and a connection portion 10. The circuit board 9 may be a circuit board designed with increased versatility so that it can be used for many models in order to reduce costs. Further, the support member 8 is preferably formed of a heat-resistant material so as not to be deformed or deteriorated at the temperature of a manufacturing process such as soldering.

The flow rate sensor chip 5, the pressure sensor chip 6, and the humidity sensor chip 7 are mounted on a circuit board. In the following description, the flow rate sensor chip 5, the pressure sensor chip 6, and the humidity sensor chip 7 may be referred to as "sensor chips". The circuit board 9 is in contact with the step portion 24 of the support member 8, and may be fixed to the step portion 24 by, for example, an adhesive 22.

The connection portion 10 and the terminal 11 inserted into the housing 2 are electrically connected by, for example, a wire 12. Each sensor chip (flow sensor chip 5, pressure sensor chip 6, and humidity sensor chip 7) has an electrical connection portion 13. The circuit board 9 and the electrical connection portion 13 are electrically connected to each other via a flexible wire rod (not shown) or directly with a solder 14.

The electrical connection portion 13 of each sensor chip is connected to an electric circuit inside each sensor chip, and may be a lead that is also exposed to the outside of each sensor chip, for example. It is preferable that each sensor chip, the wire 12, the electrical connection portion 13, and the solder 14 are protected by a highly insulating resin or gel.

As shown in FIG. 2, the flow rate sensor chip 5 includes a lead frame 15, a flow rate sensor element 16, a semiconductor chip 17, a wire 18, and a mold resin 19. A flow rate detection unit 20 is formed on the upper surface side of the flow rate sensor element 16. The flow rate detection unit 20 is a portion thinner than the surroundings. A rectangular or trapezoidal hollow portion is formed on the lower surface side of the flow rate sensor element 16, and the flow rate detecting portion 20 is thinned by this hollow portion.

The flow rate detection unit 20 has, for example, a heater control bridge and a temperature sensor bridge including a heating element and a pair of measuring resistors arranged on both sides of the heating element resistor. The heat generating resistor and the pair of measuring resistors are arranged along the direction in which a gas such as air for detecting the flow rate flows.

Specifically, in the heating resistor and the pair of measuring resistors, the measuring resistor on the upstream side of the gas flow to be measured is cooled by gas, and the measuring resistor on the downstream side is from the heating resistor. It is arranged so that it can be heated by heat. The semiconductor chip 17 is composed of a CPU, an input circuit, an output circuit, a memory, and the like, and has a control circuit for measuring a gas flow rate.

As the mold resin 19, for example, a thermosetting resin such as an epoxy resin or a phenol resin can be used. Further, metal fine particles such as gold, silver, copper and tin, or inorganic fine particles containing silica, glass, carbon, mica, talc and the like as components may be mixed. By mixing an appropriate amount of metal fine particles or inorganic fine particles, it is possible to make the resin conductive or adjust the coefficient of linear expansion of the resin.

As the lead frame 15, for example, copper, a 42% nickel lead frame material (42 alloy), or the like can be used. The flow rate sensor chip 5 is fixed to both the housing 2 and the support member 8. The flow path 21 is formed in a space surrounded by a base member 3, a housing 2, a support member 8, and the like. In order to measure the air flow rate by the flow rate detection unit 20 of the flow rate sensor chip 5, the flow rate detection unit 20 of the flow rate sensor chip 5 is mounted so as to protrude into the flow path 21 shown in FIG. The flow rate detection unit 20 is formed on the upper surface of the flow rate sensor element 16 of the flow rate sensor chip 5 and is arranged so as to be exposed to the flow path 21. As the air flows through the flow path 21, the flow rate detection unit 20 measures the air flow rate. If the height from the base member 3 indicated by the arrow in FIG. 2 to the flow rate detection unit 20 of the flow rate sensor chip 5 varies due to variations in the thickness of the circuit board or the like, the flow field in the vicinity of the flow rate detection unit 20 changes. The measured air flow rate varies. Therefore, by providing the support member 8 in contact with the flow rate sensor chip 5 and the base member 3, it is possible to suppress the height variation from the base member 3 to the flow rate detection unit 20.

FIG. 3 is a plan view showing a part of the configuration of the flow rate sensor module 1. FIG. 4 is a cross-sectional view taken along the line BB of the flow rate sensor module 1 of FIG. FIG. 5 is a sectional view taken along line CC of the flow rate sensor module 1 of FIG. Note that FIGS. 3, 4, and 5 show a part of the configuration of the flow rate sensor module 1. For example, FIGS. 3, 4, and 5 do not show the housing 2 and the cover 4. As shown in FIGS. 3 and 4, the support member 8 has a structure that straddles at least a part of the circuit board 9, and has a structure in which a part of the support members 8 that face each other across the circuit board 9 are connected. The support member 8 has a step portion 24. The step portion 24 is in contact with at least a part of the mounting surface of the circuit board 9. The step portion 24 and the circuit board 9 are fixed by the adhesive 22 at at least a part of the contact points thereof.

The support member 8 has a structure having legs protruding toward the base member 3 side from the lowermost surface of the circuit board 9. The support member 8 and the base member 3 are in contact with each other at the legs, and a space is provided between the base member 3 and the circuit board 9. Even if the thickness of the circuit board 9 varies, the legs of the support member 8 are designed to have a sufficient length so that this space exists. Due to such a structure, even if there is a thickness variation (within the allowable range in the specifications) of the circuit board 9, since there is a space between the base member 3 and the circuit board 9, the flow rate from the base member 3 It is possible to suppress the influence on the height up to the detection unit 20. Similarly, even if the circuit board 9 is warped or deformed (within the allowable range in the specifications), this space can suppress the influence on the height from the base member 3 to the flow rate detecting unit 20. Therefore, the height variation from the base member 3 to the flow rate detection unit 20 can be suppressed. The flow rate sensor chip 5 is fixed to the support member 8, and the flow rate detection unit 20 is installed so as to face the base member 3.

As shown in FIGS. 4 and 5, the support member 8 and the base member 3 are in contact with each other on at least two sides to prevent the support member 8 from tilting, and the height variation from the base member 3 to the flow rate detection unit 20. Can be suppressed. The support member 8 and the base member 3 are adhered to each other with, for example, an adhesive 22. In addition to bonding with the adhesive 22, the flow sensor chip 5 and the support member 8 are integrated by molding a part of the flow sensor chip 5 with the resin of the support member 8 before the solder connection with the circuit board 9. It is also possible to do.

When the flow rate sensor chip 5 and the support member 8 are integrated, the position of the flow rate sensor chip 5 is fixed, so that height variation due to misalignment can be suppressed. In this case, the solder 14 is melted in a state where the support member 8 and the flow rate sensor chip 5 are integrated, and adhered to the electrical connection portion 13 of the flow rate sensor chip 5 and the circuit board 9. When soldering by a heating furnace, the resin of the support member 8 needs to be a resin having high heat resistance, and for example, epoxy resin, polyetheretherketone (PEEK), polyimide, polyphenylene sulfide (PPS), or the like is preferable. is there.

[Modification of Example 1]
Hereinafter, the flow rate sensor module 1 which is a modification of the first embodiment will be described. A plan view showing a part of the configuration of the flow rate sensor module 1 which is a modification of the first embodiment is shown in FIGS. 1 and 3 as in the first embodiment. FIG. 6 is a cross-sectional view taken along the line BB in FIG. 3 of the flow rate sensor module 1 which is a modification of the first embodiment. As shown in FIG. 6, the flow rate sensor module 1 which is a modification of the first embodiment has a structure in which a notch 23 is provided in a support member 8 in contact with a circuit board 9. Further, there is at least a space between the side surface of the circuit board 9 (the side surface in the X-axis direction and the Y-axis direction) and the support member 8. The other configurations of the flow rate sensor module 1 which is a modification of the first embodiment may be the same as those of the flow rate sensor module 1 of the first embodiment. Here, during heating in a manufacturing process (for example, a soldering process), the circuit board 9 thermally expands and expands. At this time, if the side surface of the circuit board 9 comes into contact with the support member 8, a force is applied by the support member 8 from the side surface of the circuit board 9 depending on the linear expansion difference between the circuit board 9 and the support member 8, and the circuit board 9 May be deformed so that it warps greatly. As shown in FIG. 6, when the cutout portion 23 and a sufficient space are provided, it is possible to prevent the circuit board 9 from being significantly warped. This leads to prevention of soldering misalignment and reduction of load such as deformation stress on the solder 14.

[Other Modifications of Example 1]
Hereinafter, the flow rate sensor module 1a, which is another modification of the first embodiment, will be described. FIG. 7 is a plan view showing a part of the configuration of the flow rate sensor module 1a. As shown in FIG. 7, the flow rate sensor module 1a, which is another modification of the first embodiment, is the support member 8 in a plan view from the Z-axis direction from the support member 8 of the flow rate sensor module 1 of the first embodiment of FIG. It is a structure in which the side wall portion forming one side of the rectangle is removed. The support member 8 of the flow rate sensor module 1a may have two sides facing each other with the circuit board 9 in contact with the base member 3, and for example, a part of the support member 8 may be opened as shown in FIG. For example, the support member 8 of the flow rate sensor module 1a may have a U-shaped structure having three sides in a plan view from the Z-axis direction. The shape of the support member 8 can be any shape such as a circular shape, an elliptical shape, a rectangular shape, or a polygonal shape. The other configurations of the flow rate sensor module 1a may be the same as those of the flow rate sensor module 1 of the first embodiment.

Hereinafter, the flow rate sensor module 1b of the second embodiment will be described with reference to FIGS. 8 and 9. FIG. 8 is a plan view showing a part of the configuration of the flow rate sensor module 1b according to the second embodiment. FIG. 9 is a cross-sectional view taken along the line DD of the flow rate sensor module 1b of FIG. In the flow rate sensor module 1b of the second embodiment, the flow rate sensor chip 5 is supported by two opposing sides of the support member 8. As a result, the displacement of the flow rate sensor chip 5 at the time of mounting is further suppressed. The other configurations of the flow rate sensor module 1b may be the same as those of the flow rate sensor module 1 of the first embodiment.

Hereinafter, the flow rate sensor module 1c of the third embodiment will be described with reference to FIGS. 10 and 11. FIG. 10 is a plan view showing a part of the configuration of the flow rate sensor module 1c according to the third embodiment. FIG. 11 is a cross-sectional view taken along the line EE of the flow rate sensor module 1c of FIG.

As shown in FIG. 10, the support member 8 of the flow rate sensor module 1c of the third embodiment has a structure that surrounds the circuit board 9. In the support member 8 of the flow rate sensor module 1c, the end face in the negative Z direction is in contact with the base member 3 over the entire surface. In the example of FIG. 10, in a plan view from the Z axis, the four side surfaces (wall surfaces) of the support member 8 indicated by the two sides parallel to the Y axis and the two sides parallel to the X axis are in contact with the base member 3. There is. As a result, the stability of the support member 8 is improved because all the wall surfaces on all four sides are stably supported by the base member 3. Further, since the circuit board 9 is surrounded by the support member 8, it can also be used as a resin casting dam material when protecting the electrical connection portion 13 with an insulating material. As a result, waste of the resin filler and the like is reduced, so that the material efficiency can be improved. The other configurations of the flow rate sensor module 1c may be the same as those of the flow rate sensor module 1 of the first embodiment.

Although various embodiments and modifications have been described above, the present invention is not limited to these contents. The above-mentioned Examples 1 to 3 and the modified examples may be combined with each other. Other aspects conceivable within the scope of the technical idea of the present invention are also included within the scope of the present invention.

The following sensor device is also an example of the embodiment. The sensor device (for example, flow rate sensor modules 1, 1a, 1b, 1c) is installed in a passage (for example, flow path 21) and has a sensor element (for example, flow rate sensor element 16) for detecting a physical amount of gas passing through the passage. A passage is formed by a unit (for example, a flow sensor chip 5), a circuit board (for example, a circuit board 9) that is electrically connected to the detection unit, a fixing member (for example, a support member 8) that fixes the circuit board and the detection unit, respectively. A portion (for example, a base member 3) is provided. The passage forming portion is one of the surfaces forming the passage, the first portion to which the fixing member is fixed, the second portion facing the circuit board via the gap, and the third portion facing the sensor element via the passage. The portion and the portion are on the same surface.

The passage forming portion further has a fourth portion to which the fixing member is fixed on the same surface as the first portion. Between the first portion and the fourth portion to which the fixing member is fixed, there is a second portion facing the circuit board via a gap. Further, the distance between the second portion of the passage forming portion and the circuit board is shorter than the distance between the third portion of the passage forming portion and the sensor element. The sensor device further includes a housing (eg, housing 2) that forms at least a portion of the passage, along with a passage forming portion and a fixing member. The sensor element detects at least the flow rate of the gas passing through the passage as a physical quantity relating to the gas passing through the passage. The circuit board includes a calculation unit that calculates and processes the detected flow rate.

The fixing member has at least two sides that sandwich the circuit board in a plan view from the thickness direction of the circuit board. Further, the fixing member includes a first step portion and a second step portion. The first step portion includes a first fixed portion fixed to the first portion of the passage forming portion, and a second fixed portion fixed to the circuit board. The second step portion includes a third fixing portion fixed to the circuit board, and a fourth fixing portion fixed to the fourth portion of the passage forming portion. The first step portion and the second step portion are two sides that sandwich the circuit board in a plan view from the thickness direction of the circuit board. Further, there may be a gap between the first step portion of the fixing member and the first side surface of the circuit board facing the first step portion. Similarly, there may be a gap between the second step portion of the fixing member and the second side surface of the circuit board facing the second step portion.

The first step portion of the fixing member has a first groove (for example, a notch portion 23) formed in the thickness direction of the circuit board between the first fixing portion and the second fixing portion. Similarly, the second step portion of the fixing member has a second groove (for example, a notch portion 23) formed in the thickness direction of the circuit board between the third fixing portion and the fourth fixing portion. Further, at least a part of the first side surface of the circuit board is located at a position overlapping the first groove in a plan view from the thickness direction of the circuit board. Similarly, at least a part of the second side surface of the circuit board is located at a position overlapping the second groove in a plan view from the thickness direction of the circuit board.

The fixing member may have an intermediate portion between the first step portion and the second step portion. The fixing member may have three sides that are U-shaped in a plan view from the thickness direction of the circuit board. The fixing member may be a frame made of resin. The detection unit may penetrate at least a part of the frame body. In this case, the sensor element of the detection unit may be on the outside of the frame, and the portion where the detection unit and the circuit board are connected may be on the inside of the frame. Further, the fixing member may be a frame body surrounding the circuit board.

1 Flow sensor module, 2 housing, 3 base member, 4 cover, 5 flow sensor chip, 6 pressure sensor chip, 7 humidity sensor chip, 8 support member, 9 circuit board, 10 connection part, 11 terminal, 12, 18 wire, 13 Electrical connection, 14 Solder, 15 Lead frame, 16 Flow sensor element, 17 Semiconductor chip, 19 Mold resin, 20 Flow detector, 21 Flow path, 22 Adhesive, 23 Notch, 24 Step, 100 Flow sensor

Claims (11)

A detection unit installed in a passage and having a sensor element for detecting a physical quantity related to a gas passing through the passage.
A circuit board that is electrically connected to the detector,
A fixing member for fixing the circuit board and the detection unit, respectively.
A third portion to which the fixing member is fixed, a second portion facing the circuit board via a gap, and a third portion forming the passage and facing the sensor element via the passage. A passage forming portion having a portion on the same surface,
A sensor device equipped with. The passage forming portion further has a fourth portion to which the fixing member is fixed on the same surface as the first portion.
The sensor device according to claim 1, wherein the second portion facing the circuit board via a gap is provided between the first portion and the fourth portion to which the fixing member is fixed. The sensor device according to claim 2, wherein the distance between the second portion of the passage forming portion and the circuit board is shorter than the distance between the third portion of the passage forming portion and the sensor element. Further having a housing forming at least a part of the passage together with the passage forming portion and the fixing member.
The sensor element detects at least the flow rate of the gas passing through the passage as a physical quantity related to the gas passing through the passage.
The sensor device according to claim 3, wherein the circuit board includes a calculation unit that calculates and processes the detected flow rate. The sensor device according to claim 4, wherein the fixing member has at least two sides that sandwich the circuit board in a plan view from the thickness direction of the circuit board. The fixing member is
A first step portion including the first fixed portion fixed to the first portion of the passage forming portion and the second fixed portion fixed to the circuit board, and a first step portion.
A second step portion including a third fixing portion fixed to the circuit board and a fourth fixing portion fixed to the fourth portion of the passage forming portion is provided.
The sensor device according to claim 5, wherein the first step portion and the second step portion are two sides that sandwich the circuit board in a plan view from the thickness direction of the circuit board. There is a gap between the first step portion of the fixing member and the first side surface of the circuit board facing the first step portion.
The sensor device according to claim 6, wherein there is a gap between the second step portion of the fixing member and the second side surface of the circuit board facing the second step portion. The first step portion of the fixing member has a first groove formed in the thickness direction of the circuit board between the first fixing portion and the second fixing portion.
The second step portion of the fixing member has a second groove formed in the thickness direction of the circuit board between the third fixing portion and the fourth fixing portion.
At least a part of the first side surface of the circuit board is located at a position overlapping the first groove in a plan view from the thickness direction of the circuit board.
The sensor device according to claim 7, wherein at least a part of the second side surface of the circuit board is located at a position overlapping the second groove in a plan view from the thickness direction of the circuit board. The fixing member has an intermediate portion between the first step portion and the second step portion.
The sensor device according to claim 6, wherein the fixing member has three sides that are U-shaped in a plan view from the thickness direction of the circuit board. The fixing member is a frame made of resin and has a frame body.
The detection unit penetrates at least a part of the frame and
The sensor element of the detection unit is located on the outside of the frame.
The sensor device according to claim 5, wherein the portion where the detection unit and the circuit board are connected is inside the frame. The sensor device according to claim 10, wherein the fixing member is a frame body surrounding the circuit board.