Pressure sensor

Abstract

Provided is a pressure sensor capable of reducing adhesion of liquid to a detection part. This pressure sensor comprises: a base member; a detection element that is provided on the base member and has a detection part; a coating member that is provided on the base member, covers at least a part of a portion of the detection element excluding the detection part, and has a hole part that is open to the upper surface on the opposite side from the base member; a soft member that is supported on the upper surface of the coating member and is softer than the coating member; and a lid member that is supported by the soft member and closes the opening of the hole part. The detection part is exposed in the hole part. A gap space is formed in a part between the lid member and the soft member. The lid member has a first surface facing the soft member, a second surface on the opposite side to the first surface, and a through hole penetrating the lid member from the first surface to the second surface. The gap space communicates with both the hole part and the through hole.

Description

Pressure Sensor

[0001] The present invention relates to a pressure sensor for detecting external pressure.

[0002] A pressure sensor for detecting external pressure is disclosed in Japanese Patent Application Laid-Open No. 2003-222299.

[0003] The pressure sensor disclosed in Patent Document 1 includes a detection element provided on a base substrate, a resin package provided on the base substrate in which the detection element is embedded and which has an exposure hole for exposing a detection portion of the detection element to the outside, and a tubular member attached to the resin package and which has a through hole communicating with the exposure hole. The pressure sensor detects pressure acting on the detection portion from the outside through the through hole and the exposure hole.

[0004] International Publication No. 2019 / 208127

[0005] If a liquid such as water adheres to the detection portion, it is difficult to accurately detect the pressure acting on the detection portion unless the adhered liquid is removed.

[0006] In the pressure sensor disclosed in Patent Document 1, the detection unit is provided in the exposure hole. In this case, liquid enters the through hole and the exposure hole and adheres to the detection unit. In other words, the liquid adhering to the detection unit is inside the exposure hole. It is difficult to remove the liquid inside the exposure hole from the exposure hole. Therefore, in order to resume accurate detection by the detection unit with the liquid adhering inside the exposure hole, it is necessary to wait for the liquid inside the exposure hole to completely evaporate.

[0007] SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide a pressure sensor that can reduce adhesion of liquid to a detection portion.

[0008] A pressure sensor element according to one aspect of the present disclosure comprises: a base member; a detection element provided on the base member and having a detection portion; a covering member provided on the base member, covering at least a portion of the detection element excluding the detection portion, and having a hole portion opened on an upper surface opposite the base member; a soft member supported on the upper surface of the covering member and softer than the covering member; and a lid member supported on the soft member and closing the opening of the hole portion, wherein the detection portion of the detection element is exposed to the hole portion, and there is a gap space between a portion of the lid member and the soft member, and the lid member has a first surface facing the soft member, a second surface opposite the first surface, and a through hole penetrating the lid member from the first surface to the second surface, and the gap space is connected to both the hole portion and the through hole.

[0009] According to the present disclosure, it is possible to reduce adhesion of liquid to the detection unit.

[0010] FIG. 2 is a schematic plan view of the pressure sensor according to the first embodiment of the present disclosure. FIG. 3 is a schematic cross-sectional view showing the A-A cross section in FIG. 1 . FIG. 4 is a schematic cross-sectional view of a modified example of the pressure sensor according to the first embodiment of the present disclosure. FIG. 5 is a schematic cross-sectional view of a modified example of the pressure sensor according to the first embodiment of the present disclosure, taken at a position corresponding to the A-A cross section in FIG. 1 of the modified example of the pressure sensor according to the first embodiment of the present disclosure. FIG. 6 is a schematic cross-sectional view of a modified example of the pressure sensor according to the first embodiment of the present disclosure. FIG. 7 is a schematic cross-sectional view of a pressure sensor according to a second embodiment of the present disclosure, taken at a position corresponding to the A-A cross section in FIG.

[0011] An example of the present disclosure will now be described with reference to the accompanying drawings. Note that the following description is merely illustrative in nature and is not intended to limit the present disclosure, its applications, or its uses. The drawings are schematic, and the ratios of dimensions and the like do not necessarily correspond to reality. Furthermore, in the following description, terms indicating specific directions or positions (e.g., terms including "upper," "lower," "right," "left," "front," and "rear") are used as necessary. However, the use of terms indicating specific directions or positions is intended to facilitate understanding of the present disclosure with reference to the drawings, and the meanings of these terms do not limit the technical scope of the present disclosure.

[0012] <First embodiment> Fig. 1 is a schematic plan view of a pressure sensor according to a first embodiment of the present disclosure. Fig. 2 is a schematic cross-sectional view showing the A-A cross section of Fig. 1. The pressure sensor 10 is capable of detecting pressure, and is mounted on, for example, a moving object such as an automobile, or an electronic device such as a smartphone or a smartwatch.

[0013] As shown in FIGS. 1 and 2, the pressure sensor 10 includes a base member 20, a circuit element 30, a detection element 40, a covering member 50, a soft member 60, and a lid member 70.

[0014] 2 is a rigid substrate such as a glass epoxy substrate or a ceramic substrate, but is not limited to this. For example, the base member 20 may be a lead frame.

[0015] As shown in Fig. 2, external electrodes 21 are provided on the lower surface 20A of the base member 20. When the pressure sensor 10 is mounted on another external device, such as the electronic device described above, the pressure sensor 10 is electrically connected to the electronic device via the external electrodes 21. Although four external electrodes 21 are shown in Fig. 2, the number of external electrodes 21 provided on the pressure sensor 10 is not limited to four.

[0016] As shown in FIG. 2 , the circuit element 30 and the detection element 40 are mounted on the upper surface 20B of the base member 20. That is, the circuit element 30 and the detection element 40 are provided on the base member 20. The base member 20 has electrodes (not shown) on the upper surface 20B. The electrodes provided on the upper surface 20B are electrically connected to the circuit element 30 via bonding wires 81 and to the detection element 40 via bonding wires 82. The bonding wires 81 and 82 are electrically connected to each other via a wiring pattern (not shown) provided on the upper surface 20B of the base member 20. As a result, the circuit element 30 and the detection element 40 are electrically connected to each other. Note that the circuit element 30 and the detection element 40 may be directly connected to each other via bonding wires. Note that the electrodes provided on the upper surface 20B may be electrically connected to the external electrode 21, for example, via an internal electrode or via conductor provided inside the base member 20.

[0017] In the first embodiment, the circuit element 30 is an element including an application specific integrated circuit (ASIC). The circuit element 30 is adhered to the upper surface 20B of the base member 20 by, for example, a die attach film or a die attach material.

[0018] The circuit element 30 includes a signal processing circuit that processes the signal output from the detection element 40 and outputs the processed signal to the base member 20. For example, in the first embodiment, the circuit element 30 includes a converter, a filter, a temperature sensor, a processor, a memory, and the like. The converter converts the voltage signal output from the detection element 40 into a digital signal. The filter filters the digital signal from the converter. The temperature sensor detects temperature. The processor corrects the filtered digital signal based on the temperature detected by the temperature sensor. The memory stores correction coefficients and the like used when correcting the digital signal using the detected temperature.

[0019] The detection element 40 is a pressure sensor element for measuring pressure. The detection element 40 is, for example, a piezoresistance type pressure sensor element or a capacitance type pressure sensor element, and is a microelectromechanical systems (MEMS) element. The detection element 40 is adhered to the upper surface 20B of the base member 20 by, for example, a die attach film or a die attach material. In the first embodiment, the detection element 40 is mounted on the upper surface 20B of the base member 20, but the detection element 40 may also be mounted on the circuit element 30.

[0020] The detection element 40 has a detection unit 41 on its upper surface, on which pressure from outside the detection element 40 acts. That is, the detection unit 41 detects pressure. The detection unit 41 is, for example, a membrane or diaphragm that receives pressure. The detection unit 41 may be provided with, for example, a passivation film and be waterproof.

[0021] The covering member 50 is provided on the base member 20. The covering member 50 is a package produced by molding a hard resin, such as a thermosetting resin, onto the upper surface 20B of the base member 20. The upper surface 20B of the base member 20 is protected and waterproof by being covered with the covering member 50.

[0022] The circuit element 30, the detection element 40, and the bonding wires 81, 82 are embedded in the covering member 50. By being embedded in the covering member 50, the circuit element 30, the detection element 40, and the bonding wires 81, 82 are protected and waterproofed.

[0023] A portion of the upper surface of the detection element 40 is not embedded in the covering member 50. Here, the portion of the upper surface of the detection element 40 is the detection unit 41 provided on the upper surface and the portion of the upper surface surrounding the detection unit 41. In other words, the covering member 50 covers the portion of the detection element 40 excluding the detection unit 41 and the surrounding portion. In other words, the covering member 50 covers the entire portion of the detection element 40 excluding the detection unit 41. Note that the covering member 50 may also cover the surrounding portion. In other words, the covering member 50 may cover the entire portion of the detection element 40 excluding the detection unit 41. As described above, the covering member 50 covers at least a portion of the portion of the detection element 40 excluding the detection unit 41.

[0024] The covering member 50 includes a base portion 51 and a protrusion portion 52 .

[0025] The base 51 constitutes the portion of the covering member 50 that faces the base member 20 in the vertical direction 100. The base 51 is in contact with the upper surface 20B of the base member 20. In the first embodiment, the circuit element 30, the lower portions of the detection element 40, the bonding wires 81, and the lower portions of the bonding wires 82 are covered by the base 51.

[0026] The protruding portion 52 protrudes from the base 51 so as to be away from the base member 20. In other words, the protruding portion 52 protrudes upward from the upper surface 51A of the base 51. That is, in the first embodiment, the protruding direction of the protruding portion 52 is the vertical direction 100. The protruding portion 52 constitutes the side of the covering member 50 opposite the base member 20 with respect to the base 51 in the vertical direction 100. In the first embodiment, the upper portion of the detection element 40 and the upper portion of the bonding wire 82 are covered by the protruding portion 52.

[0027] The protrusion 52 has an upper surface 52A and an outer surface 52B. The upper surface 52A is the top surface of the protrusion 52. The upper surface 52A is located on the side of the protrusion 52 opposite the base member 20 in the vertical direction 100. The outer surface 52B extends downward from the outer edge of the upper surface 52A when viewed along the vertical direction 100. The outer surface 52B connects the upper surface 52A of the protrusion 52 and the upper surface 51A of the base 51.

[0028] When viewed in the vertical direction 100, the base 51 protrudes outward from the outer surface 52B of the protrusion 52. In the first embodiment, the protrusion 52 is provided in the center of the base 51 when viewed in the vertical direction 100.

[0029] The protrusion 52 has a hole 52C. The hole 52C has an opening 52Ca that opens in the upper surface 52A. The hole 52C extends downward from the opening 52Ca toward the base 51. The hole 52C has an inner surface 52D and a bottom surface 52E. The inner surface 52D extends downward from the inner edge of the upper surface 52A when viewed along the vertical direction 100. The inner surface 52D connects the upper surface 52A and the bottom surface 52E.

[0030] The portion of detection element 40 that is not covered by covering member 50, i.e., detection portion 41 of detection element 40 and the surrounding portion of detection portion 41 on the upper surface of detection element 40, are exposed in hole 52C. In the first embodiment, bottom surface 52E of hole 52C is formed by the resin that forms protrusion 52, detection portion 41, and the surrounding portion. In other words, detection portion 41 and the surrounding portion are part of bottom surface 52E of hole 52C.

[0031] The detecting portion 41 and the surrounding area may form the entire bottom surface 52E. When the covering member 50 covers the entire detecting element 40 except for the detecting portion 41, the entire bottom surface 52E may be formed by the resin forming the protruding portion 52 and the detecting portion 41, or the entire bottom surface 52E may be formed by the detecting portion 41 alone.

[0032] In the first embodiment, the shape of the hole 52C is a tapered shape in which the cross-sectional area along an imaginary plane perpendicular to the up-down direction 100 decreases as the hole approaches the detection unit 41 of the detection element 40 from the opening 52Ca, as shown in FIG. 2 , but it may have another shape. For example, the inner surface 52D of the hole 52C may extend straight downward. It is sufficient for the hole 52C to function as a pressure introducing hole that introduces pressure into the detection unit 41.

[0033] The soft member 60 is located on the opposite side of the base member 20 with respect to the covering member 50 in the up-down direction 100. The soft member 60 is supported by the covering member 50. In detail, the soft member 60 is in contact with the upper surface 51A of the base 51, the upper surface 52A of the protruding portion 52, and the outer surface 52B of the protruding portion 52, and is supported by the upper surfaces 51A, 52A, and the outer surface 52B.

[0034] The soft member 60 is made of a material that is softer than the covering member 50. In the first embodiment, the soft member 60 is made of, for example, silicon or rubber. Note that the material of the soft member 60 is not limited to silicon or rubber as long as it is softer than the covering member 50.

[0035] In the first embodiment, the covering member 50 and the soft member 60 are integrally formed by two-color molding. Note that the covering member 50 and the soft member 60 may be joined by means other than two-color molding, such as thermocompression bonding or bonding with an adhesive.

[0036] The soft member 60 has a support portion 61 and a surrounding portion 62 .

[0037] The support portion 61 is an inner portion of the soft member 60 when viewed along the vertical direction 100. The support portion 61 is in contact with the upper surface 52A of the protrusion 52 and is supported by the upper surface 52A. When viewed along the vertical direction 100, the support portion 61 is annular and is provided so as to surround the opening 52Ca of the hole 52C of the protrusion 52. In other words, the soft member 60 does not block the opening 52Ca of the hole 52C. The support portion 61 may extend up to just above the hole 52C. However, in this case, the support portion 61 extending up to just above the hole 52C does not completely block the opening 52Ca of the hole 52C. Therefore, the gap space 90 (described later) is not prevented from communicating with the hole 52C.

[0038] The surrounding portion 62 is formed integrally with the support portion 61. The surrounding portion 62 is an outer portion of the soft member 60 when viewed along the vertical direction 100. The surrounding portion 62 is in contact with the upper surface 51A of the base 51 and is supported by the upper surface 51A. The surrounding portion 62 is annular when viewed along the vertical direction 100 and is provided so as to surround the protruding portion 52. The surrounding portion 62 has an inner circumferential surface 62A. The inner circumferential surface 62A is in contact with the outer surface 52B of the protruding portion 52. This closes the gap between the soft member 60 and the protruding portion 52. Furthermore, the surrounding portion 62 is supported not only by the upper surface 51A but also by the outer surface 52B.

[0039] The upper surface of the soft member 60 is an opposing surface 60A that faces a first surface 70A of the lid member 70, which is the lower surface of the lid member 70, in the vertical direction 100. The opposing surface 60A is the surface of the soft member 60 that is located on the opposite side from the covering member 50 in the vertical direction 100.

[0040] The opposing surface 60A has a separation surface 60B and a support surface 60C. The separation surface 60B is provided on the support portion 61. The separation surface 60B is spaced apart from the first surface 70A of the lid member 70. The support surface 60C is provided on the enclosing portion 62. The support surface 60C is in contact with the first surface 70A of the lid member 70 and supports the first surface 70A. In other words, the support surface 60C is located closer to the first surface 70A than the separation surface 60B.

[0041] The separating surface 60B is inclined downward as it extends inward when viewed along the up-down direction 100. In other words, the separating surface 60B is inclined so as to move away from the first surface 70A of the cover member 70 as it approaches the hole portion 52C.

[0042] 1, the separation surface 60B is provided on the opposing surface 60A over the entire circumferential area of ​​the annular protrusion 52. Note that the separation surface 60B may be provided on only a portion of the opposing surface 60A in the circumferential direction of the annular protrusion 52, as shown, for example, as an area surrounded by two alternate long and short dash lines and two broken lines in FIG. 1. In this case, the portion of the annular protrusion 52 in the circumferential direction where the separation surface 60B is not provided becomes the support surface 60C.

[0043] 2, the lid member 70 is located on the opposite side of the soft member 60 from the covering member 50 in the up-down direction 100. The lid member 70 is supported by a support surface 60C on the opposing surface 60A of the soft member 60. The lid member 70 is also provided above the opening 52Ca of the hole portion 52C. In other words, the lid member 70 closes the opening 52Ca of the hole portion 52C from above.

[0044] In the first embodiment, the lid member 70 is made of a resin such as a liquid crystal polymer. The lid member 70 is not limited to a resin, and may be made of a metal such as stainless steel (SUS). In the first embodiment, the lid member 70 is made harder than the soft member 60, but it may be softer than the soft member 60 or may have the same hardness. The lid member 70 is joined to the soft member 60 by, for example, an adhesive.

[0045] The lid member 70 has a first surface 70A and a second surface 70B. The first surface 70A is the bottom surface of the lid member 70 and faces the soft member 60 and the hole 52C of the covering member 50. The second surface 70B is the top surface of the lid member 70 and is located on the opposite side of the first surface 70A in the vertical direction 100.

[0046] The first surface 70A faces the opposing surface 60A of the soft member 60 in the up-down direction 100. The first surface 70A is spaced apart from the separation surface 60B of the opposing surface 60A of the soft member 60. Because the first surface 70A and the separation surface 60B are spaced apart, a gap space 90 is provided between the first surface 70A and the separation surface 60B. In other words, the separation surface 60B faces the gap space 90. On the other hand, because the first surface 70A is in contact with the support surface 60C of the opposing surface 60A of the soft member 60, no gap space 90 is provided between the first surface 70A and the support surface 60C. In other words, the gap space 90 is provided in a portion between the cover member 70 and the soft member 60.

[0047] The gap space 90 communicates with the inside of the annular support portion 61 of the soft member 60. In other words, the gap space 90 communicates with the hole portion of the annular support portion 61. As a result, the gap space 90 communicates with the hole portion 52C of the covering member 50.

[0048] 1 and 2, the cover member 70 has two through holes 70C. Each of the two through holes 70C penetrates the cover member 70 in the up-down direction 100 from the first surface 70A to the second surface 70B. Note that the number of through holes 70C in the cover member 70 is not limited to two.

[0049] Each of the two through holes 70C overlaps with the gap space 90 when viewed in the up-down direction 100. As a result, the gap space 90 communicates with the through holes 70C.

[0050] As described above, the detection unit 41 of the detection element 40 is in communication with the outside of the pressure sensor 10 via the hole 52C, the gap space 90, and the through-hole 70C. Therefore, gas acting on the second surface 70B of the cover member 70 acts on the detection unit 41 via the through-hole 70C, the gap space 90, and the hole 52C. This allows the detection element 40 to measure the pressure applied to the detection unit 41 by the gas acting on the detection unit 41.

[0051] 1, when viewed in the vertical direction 100, each of the two through holes 70C is circular. That is, each of the two through holes 70C is cylindrical. When viewed in the vertical direction 100, the two through holes 70C are provided at positions that are point-symmetric with respect to the center C of the pressure sensor 10. The two through holes 70C have the same shape and size.

[0052] The size, shape, and position of the through holes 70C are not limited to those shown in Figures 1 and 2 and described above. The shapes and sizes of the through holes 70C may be the same as or different from each other. The positions of the through holes 70C do not have to be point-symmetric with respect to the center C of the pressure sensor 10.

[0053] In the first embodiment, the size, shape, and position of the through-hole 70C are set so as to satisfy both the first condition and the second condition.

[0054] The first condition is that when a first pressure acts on the second surface 70B by liquid adhering to the second surface 70B so as to cover the through hole 70C, the liquid covering the through hole 70C enters the through hole 70C.

[0055] The first pressure is a large pressure. For example, when the first pressure is applied to the second surface 70B by the liquid adhering to the second surface 70B, the first pressure becomes larger than the surface tension of the liquid located at the boundary with the opening of the through hole 70C. This causes the liquid to enter the through hole 70C.

[0056] The second condition is that when a second pressure lower than the first pressure acts on the second surface 70B due to liquid adhering to the second surface 70B so as to cover the through hole 70C, the liquid covering the through hole 70C does not enter the through hole 70C.

[0057] The second pressure is a slight pressure. For example, even if the second pressure is applied to the second surface 70B by the liquid adhering to the second surface 70B, the second pressure is smaller than the surface tension of the liquid located at the boundary with the opening of the through hole 70C. Therefore, the liquid remains located at the boundary with the opening of the through hole 70C due to the surface tension and does not enter the through hole 70C.

[0058] When a first pressure is applied to the second surface 70B by the liquid adhering to the second surface 70B, the soft member 60 is compressed by the action of the first pressure. This causes the separating surface 60B of the soft member 60 to come into contact with the first surface 70A of the cover member 70. As a result, at least a portion of the gap space 90 is closed. In other words, the first pressure is a pressure at which the above-described closing of the gap space 90 occurs.

[0059] When the second pressure acts on the second surface 70B due to the liquid adhering to the second surface 70B, the compression of the soft member 60 due to the action of the second pressure is smaller than the compression of the soft member 60 due to the action of the first pressure. Alternatively, when the second pressure acts on the second surface 70B due to the liquid adhering to the second surface 70B, the soft member 60 is not compressed by the action of the second pressure. Therefore, the separation surface 60B of the soft member 60 is maintained in a state separated from the first surface 70A of the lid member 70. As a result, communication between the through hole 70C and the hole portion 52C via the gap space 90 is maintained. In other words, the second pressure is a pressure that maintains communication between the through hole 70C and the hole portion 52C via the gap space 90 as described above.

[0060] For example, the first pressure is greater than 1 bar, i.e., 100 kilopascals (kPa), and the second pressure is less than 1 bar.

[0061] <Modifications> The configurations of the components of the pressure sensor 10, such as the base member 20, the detection element 40, the covering member 50, the soft member 60, and the lid member 70, such as their shapes and sizes, are not limited to those described above and shown in the figures. For example, the protruding portion 52 of the covering member 50 is cylindrical as shown in FIGS. 1 and 2, but may be a rectangular prism or other shape. Furthermore, the covering member 70 is disk-shaped, but may be a rectangular plate or other shape. Furthermore, the soft member 60 only needs to be supported on the upper surface of the covering member 50. Therefore, for example, while the soft member 60 in the first embodiment includes the support portion 61 and the surrounding portion 62, the soft member 60 may include only the support portion 61 without the surrounding portion 62.

[0062] 1 and 2 , the through hole 70C is located at a position overlapping the support portion 61 of the soft member 60 in the vertical direction 100. However, the position of the through hole 70C is arbitrary, provided that the through hole 70C communicates with the gap space 90. For example, the through hole 70C may be located at a position overlapping the surrounding portion 62 of the soft member 60 in the vertical direction 100. In this case, the separation surface 60B is provided across both the support portion 61 and the surrounding portion 62, and the through hole 70C is located at a position overlapping the separation surface 60B provided on the surrounding portion 62 in the vertical direction 100.

[0063] The number, size, and shape of the through holes 70C in the lid member 70 are arbitrary. An example of the configuration of the through holes 70C is described in Figures 3 and 4. Figure 3 is a schematic plan view of a modified example of the pressure sensor according to the first embodiment of the present disclosure. Figure 4 is a schematic plan view of a modified example of the pressure sensor according to the first embodiment of the present disclosure. In the following description of the modified examples, the same reference numerals are used for configurations that have been described previously, and descriptions thereof will be omitted in principle and will be described only as necessary.

[0064] 3, the cover member 70 has eight through holes 70C. The eight through holes 70C are arranged at equal intervals on the same imaginary arc when viewed in the up-down direction 100.

[0065] In a modified pressure sensor 10B shown in Fig. 4, the cover member 70 has four through holes 70C. Each of the four through holes 70C is an elongated hole that extends along the same imaginary arc when viewed along the vertical direction 100. The four through holes 70C are provided at equal intervals on the same imaginary arc when viewed along the vertical direction 100.

[0066] FIG. 5 is a schematic cross-sectional view showing a cross section of a modified example of the pressure sensor according to the first embodiment of the present disclosure, taken along a position corresponding to the cross section AA in FIG.

[0067] In the pressure sensor 10C shown in FIGS. 1 and 2, the opposing surface 60A of the soft member 60 has a separating surface 60B that is inclined so as to move away from the first surface 70A of the lid member 70 as it approaches the hole portion 52C.

[0068] However, like the pressure sensor 40C shown in Fig. 5, the separating surface 60B does not have to be inclined. That is, the separating surface 60B may be parallel to the supporting surface 60C. In this case, the opposing surface 60A may have a stepped surface 60D in addition to the separating surface 60B and the supporting surface 60C.

[0069] The step surface 60D is provided between the separating surface 60B and the supporting surface 60C. In other words, the separating surface 60B and the supporting surface 60C are connected via the step surface 60D. The step surface 60D extends in the vertical direction 100. The separating surface 60B is located below the supporting surface 60C. In other words, the separating surface 60B is located closer to the base member 20 than the supporting surface 60C in the vertical direction 100. This provides a gap space 90 between the separating surface 60B and the first surface 70A of the cover member 70.

[0070] 6 is a schematic plan view of a modified example of the pressure sensor according to the first embodiment of the present disclosure. In the pressure sensor 10D shown in FIG. 6, the separation surface 60B and the step surface 60D are provided on a part of the opposing surface 60A in the circumferential direction of the annular protrusion 52. As a result, the gap space 90 formed by the separation surface 60B and the step surface 60D has a thin, elongated slit shape.

[0071] Note that the configuration in which the separation surface 60B is an inclined surface as shown in Fig. 1 may be changed to a configuration in which the clearance space 90 is slit-shaped as shown in Fig. 6. For example, as described above, in Fig. 1, only the region of the opposing surface 60A surrounded by two dashed lines and two broken lines may be the separation surface 60B. In this case, the slit-shaped clearance space 90A is provided in that region.

[0072] According to the first embodiment, the detection portion 41 of the detection element 40 is connected to the outside of the pressure sensor 10 through the through-hole 70C of the lid member 70, the gap space 90, and the hole 52C of the covering member 50. This makes it possible to measure the pressure acting on the detection portion 41 from the outside.

[0073] According to the first embodiment, the cover member 70 covers the opening 52Ca of the hole 52C, so that foreign matter such as liquid can be prevented from adhering to the detection unit 41.

[0074] When excessive pressure acts on the second surface 70B of the lid member 70 due to the adhesion of liquid such as water to the second surface 70B, the soft member 60 is compressed by the pressure. This causes the soft member 60 to come into contact with the through-hole 70C, blocking at least a portion of the gap space 90. As a result, even if liquid adhering to the second surface 70B of the lid member 70 enters the through-hole 70C, it is possible to reduce the possibility that the liquid will enter the hole portion 52C and reach the detection unit 41. In other words, it is possible to reduce the possibility that liquid will adhere to the detection unit 41.

[0075] According to the first embodiment, all or most of the liquid adhering to the second surface 70B of the lid member 70 does not enter the hole 52C, but remains on the second surface 70B of the lid member 70. The liquid on the second surface 70B of the lid member 70 can be more easily removed by tilting the pressure sensor 10 than the liquid inside the hole 52C. As a result, measurement by the detection unit 41 can be performed without waiting for the liquid to completely evaporate.

[0076] According to the first embodiment, when an excessive first pressure is applied by liquid adhering to the second surface 70B of the lid member 70, at least a portion of the gap space 90 is blocked. In this case, the first pressure may become higher than the surface tension of the liquid covering the through hole 70C, and the liquid on the second surface 70B may enter the through hole 70C. However, as described above, because at least a portion of the gap space 90 is blocked, it is possible to prevent the liquid from passing through the gap space 90 and entering the hole portion 52C.

[0077] According to the first embodiment, when a slight second pressure is applied to the second surface 70B of the cover member 70, the gap space 90 is not closed. In this case, the second pressure is lower than the surface tension of the liquid covering the through hole 70C, and therefore the liquid on the second surface 70B does not enter the through hole 70C. This prevents the liquid from entering the hole 52C.

[0078] According to the first embodiment, the opposing surface 60A of the soft member 60 has two surfaces at different heights: a separation surface 60B and a support surface 60C. This allows the separation surface 60B to form a gap space 90, and the support surface 60C allows the soft member 60 to support the lid member 70.

[0079] According to the first embodiment, the gap space 90 is realized by the inclination of the separating surface 60B of the soft member 60. As a result, when the soft member 60 is compressed by the action of pressure caused by liquid adhering to the second surface 70B, the cover member 70 comes into close contact with the soft member 60 along the inclination of the separating surface 60B of the soft member 60. Therefore, the gap space 90 can be efficiently closed.

[0080] According to the first embodiment, the covering member 50 and the soft member 60 are integrally formed by two-color molding, and therefore the covering member 50 and the soft member 60 can be firmly joined together.

[0081] When the pressure sensor 10 is attached to the housing (not shown) of an electronic device, the gap between the housing and the pressure sensor 10 may be sealed with a sealing member such as an O-ring made of silicon, rubber, or the like. In this case, liquid is prevented from entering the interior of the electronic device from the outside through the gap. According to the first embodiment, the soft member 60 can be used as the sealing member.

[0082] Second Embodiment Figure 7 is a schematic cross-sectional view showing a cross section of a pressure sensor according to a second embodiment of the present disclosure at a position corresponding to cross section A-A in Figure 1. The pressure sensor according to the second embodiment differs from the pressure sensor according to the first embodiment in that the cover member 70 has a recess 70D, and the soft member 60 and the covering member 50 are joined together with an adhesive 84. Differences from the first embodiment will be described below. Points in common with the pressure sensor according to the first embodiment are denoted by the same reference numerals, and explanations thereof will be omitted in principle, and will be described only when necessary.

[0083] As shown in FIG. 7, in a pressure sensor 10E according to the second embodiment, a cover member 70 has a recess 70D on a first surface 70A.

[0084] The recess 70D is a portion of the first surface 70A that is recessed upward. In other words, the recess 70D is a portion of the first surface 70A that is recessed in a direction away from the covering member 50. The recess 70D may be provided so as to face the soft member 60 over the entire circumferential direction of the annular soft member 60, or may be provided so as to face the soft member 60 over a portion of the circumferential direction.

[0085] The bottom surface of the recess 70D is a separation surface 70Aa. The separation surface 70Aa is a part of the first surface 70A. The separation surface 70Aa is separated from the soft member 60. A part of the separation surface 70Aa faces the support portion 61 of the soft member 60 in the up-down direction 100. As a result, a gap space 90 is provided between the separation surface 70Aa and the support portion 61. In other words, the separation surface 70Aa faces the gap space 90. The remaining part of the separation surface 70Aa excluding the part faces the hole portion 52C of the covering member 50. As a result, the gap space 90 is in communication with the hole portion 52C.

[0086] The through-hole 70C penetrates the cover member 70 in the up-down direction 100 from the separating surface 70Aa of the first surface 70A to the second surface 70B, so that the gap space 90 communicates with the through-hole 70C.

[0087] The first surface 70A of the cover member 70 has a supported surface 70Ab and a blocking surface 70Ac in addition to the separating surface 70Aa of the recess 70D described above.

[0088] The supported surface 70Ab is in contact with the soft member 60 and is supported by the soft member 60. In other words, the supported surface 70Ab is located closer to the soft member 60 than the separating surface 70Aa.

[0089] The blocking surface 70Ac faces the hole 52C of the covering member 50 in the vertical direction 100. The blocking surface 70Ac closes the opening 52Ca of the hole 52C. In the second embodiment, the blocking surface 70Ac and the supported surface 70Ab are located on the same imaginary plane, but they may be located on different imaginary planes.

[0090] In the first embodiment described above, the opposing surface 60A of the soft member 60 is composed of two surfaces (the separating surface 60B and the supporting surface 60C). On the other hand, in the second embodiment, the opposing surface 60A of the soft member 60 is composed of a single surface. A portion of the opposing surface 60A faces the recess 70D of the lid member 70 and faces the separating surface 70Aa in the up-down direction 100. The remaining portion of the opposing surface 60A excluding the portion in question is in contact with the supported surface 70Ab of the lid member 70 and supports the supported surface 70Ab.

[0091] In the second embodiment, similarly to the first embodiment, the opposing surface 60A of the soft member 60 may be configured with two surfaces (a separating surface 60B and a supporting surface 60C).

[0092] In the pressure sensor 10E according to the second embodiment, the soft member 60 and the covering member 50 are joined together via an adhesive 84 such as a die attach film or a die attach material. The soft member 60 and the lid member 70 are joined together via an adhesive 83 such as a die attach film or a die attach material.

[0093] According to the second embodiment, the first surface 70A of the cover member 70 has two surfaces at different heights: a separating surface 70Aa and a supported surface 70Ab. This allows the separating surface 70Aa to form a gap space 90, and the supported surface 70Ab allows the cover member 70 to be supported by the soft member 60.

[0094] According to the second embodiment, the shape of the cover member 70 has a separating surface 70Aa and a supported surface 70Ab. It is easier to configure the dimensions and positions of the separating surface 70Aa and the supported surface 70Ab of the cover member 70 with high precision than to configure the dimensions and positions of the separating surface 60B and the supporting surface 60C of the soft member 60 with high precision.

[0095] According to the second embodiment, the covering member 50 and the soft member 60 are joined together with the adhesive 84, which makes it easy to join the covering member 50 and the soft member 60 together.

[0096] The pressure sensor described above can be expressed as follows.

[0097] (1) A pressure sensor according to one aspect of the present disclosure comprises: a base member; a detection element provided on the base member and having a detection portion; a covering member provided on the base member, covering at least a portion of the detection element excluding the detection portion, and having a hole portion opened on an upper surface opposite the base member; a soft member supported on the upper surface of the covering member and softer than the covering member; and a lid member supported on the soft member and closing the opening of the hole portion, wherein the detection portion of the detection element is exposed to the hole portion, and there is a gap space between a portion of the lid member and the soft member, and the lid member has a first surface facing the soft member, a second surface opposite to the first surface, and a through hole penetrating the lid member from the first surface to the second surface, and the gap space is in communication with both the hole portion and the through hole.

[0098] (2) In the pressure sensor of (1), the size, shape, and position of the through hole may be set to satisfy both a first condition and a second condition, and the first condition may be a condition that when a first pressure is applied to the second surface by a liquid adhering to the second surface so as to cover the through hole, the liquid covering the through hole enters the through hole, and the second condition may be a condition that when a second pressure lower than the first pressure is applied to the second surface by a liquid adhering to the second surface so as to cover the through hole, the liquid covering the through hole does not enter the through hole, and the first pressure may be a pressure at which the soft member is compressed by the action of the first pressure on the second surface, thereby bringing the soft member into contact with the lid member and blocking at least a portion of the gap space, and the second pressure may be a pressure at which the soft member is maintained separated from the lid member even when the second pressure is applied to the second surface.

[0099] (3) In the pressure sensor of (1) or (2), the opposing surface of the soft member that faces the first surface may have a separating surface that faces the gap space and is spaced apart from the first surface, and a supporting surface that is located closer to the first surface than the separating surface and supports the first surface.

[0100] (4) In the pressure sensor of (3), the separating surface of the opposing surface of the soft member may be inclined so as to move away from the first surface as it approaches the hole portion.

[0101] (5) In the pressure sensor of (1) or (2), the first surface of the cover member may have a separating surface facing the gap space and separated from the soft member, and a supported surface positioned closer to the soft member than the separating surface and supported by the soft member.

[0102] (6) In the pressure sensor according to any one of (1) to (5), the covering member and the soft member may be integrally formed by two-color molding.

[0103] (7) In the pressure sensor according to any one of (1) to (5), the covering member and the soft member may be joined together via an adhesive.

[0104] (8) In any one of the pressure sensors (1) to (7), the covering member may include a base that covers the detection element, and a protrusion that protrudes from the base and has the hole, and the soft member may include a support that is supported on an upper surface of the protrusion, and a surrounding portion that surrounds the protrusion when viewed along the protrusion direction of the protrusion and is in contact with an outer surface of the protrusion.

[0105] Any of the various embodiments described above may be combined appropriately to achieve the effects of each of them.

[0106] While the present invention has been fully described in connection with preferred embodiments, with appropriate reference to the drawings, various changes and modifications will become apparent to those skilled in the art, and it is to be understood that such changes and modifications are included within the scope of the present invention as defined by the appended claims unless they depart therefrom.

[0107] REFERENCE SIGNS LIST 10 Pressure sensor 20 Base member 40 Detection element 41 Detection section 50 Covering member 51 Base 52 Projection 52A Upper surface 52B Outer surface 52C Hole 60 Soft member 60A Opposing surface 60B Separating surface 60C Supporting surface 61 Supporting section 62 Surrounding section 70 Lid member 70A First surface 70Aa Separating surface 70Ab Supported surface 70B Second surface 70C Through hole 83 Adhesive 90 Gap space

Claims

1. A base member, a detection element provided on the base member and having a detection part, a covering member provided on the base member, covering at least a part of the portion of the detection element excluding the detection part, and having a hole opened on the upper surface on the side opposite to the base member, a soft member supported on the upper surface of the covering member and softer than the covering member, and a lid member supported by the soft member and closing the opening of the hole. The detection part of the detection element is exposed in the hole. There is a gap space in a part between the lid member and the soft member. The lid member has a first surface facing the soft member, a second surface opposite to the first surface, and a through hole penetrating the lid member from the first surface to the second surface. The gap space communicates with both the hole and the through hole. A pressure sensor.

2. The size, shape, and position of the through hole are set to satisfy both a first condition and a second condition. The first condition is that when a first pressure acts on the second surface by a liquid attached to the second surface so as to cover the through hole, the liquid covering the through hole enters the through hole. The second condition is that when a second pressure lower than the first pressure acts on the second surface by a liquid attached to the second surface so as to cover the through hole, the liquid covering the through hole does not enter the through hole. The first pressure is a pressure at which the soft member contacts the lid member and at least a part of the gap space is blocked by compression of the soft member due to the action of the first pressure on the second surface. The second pressure is a pressure at which the soft member remains separated from the lid member even when the second pressure acts on the second surface. The pressure sensor according to claim 1.

3. The opposing surface of the soft member facing the first surface has a separated surface facing the gap space and away from the first surface, and a support surface located closer to the first surface than the separated surface and supporting the first surface. The pressure sensor according to claim 1 or 2.

4. The separated surface of the opposing surface of the soft member is inclined so as to move away from the first surface as it approaches the hole. The pressure sensor according to claim 3.

5. The first surface of the lid member faces the gap space, and has a separation surface that is away from the soft member, and a supported surface that is located closer to the soft member than the separation surface and is supported by the soft member. The pressure sensor according to claim 1 or 2.

6. The pressure sensor according to any one of claims 1 to 5, wherein the covering member and the soft member are integrally formed by two-color molding.

7. The pressure sensor according to any one of claims 1 to 5, wherein the covering member and the soft member are joined via an adhesive.

8. The covering member includes a base portion that covers the detection element, and a protruding portion that protrudes from the base portion and has the hole portion. The soft member includes a support portion supported on the upper surface of the protruding portion, and a surrounding portion that surrounds the protruding portion when viewed along the protruding direction of the protruding portion and contacts the outer surface of the protruding portion. The pressure sensor according to any one of claims 1 to 7.

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