Pressure sensor

Abstract

A pressure sensor according to the present disclosure comprises: a substrate; a detection element provided on the upper surface of the substrate; and coating resin that covers a part of the detection element. The coating resin has a coating recess that exposes at least a part of the detection element. The detection element has: a detection part on which pressure acts; a groove part recessed downward from the element upper surface and surrounding the detection part; and an inner recess part provided contiguously with the groove part between the groove part and the detection part and recessed downward shallower than the groove part. The inner recess part has a side surface extending downward from the element upper surface, and a bottom surface extending from the lower edge of the side surface of the inner recess part toward an outer surface and connecting the side surface of the inner recess part and the inner surface of the groove part.

Description

Pressure Sensor

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

[0002] A conventional sensor of this type is known, for example, from the sensor described in Patent Document 1. The sensor described in Patent Document 1 includes a plate-shaped base, a semiconductor substrate provided on the upper surface of the base, and a coating resin provided on the upper surface of the base so as to cover a portion of the semiconductor substrate. The semiconductor substrate has a recess recessed upward from its lower surface, which is the surface that contacts the base. The bottom of the recess forms a detection section to which a resistor or the like for measuring flow rate is attached.

[0003] The semiconductor substrate is provided with an annular groove recessed downward from the upper surface of the semiconductor substrate and surrounding the detection portion in a plan view, and the coating resin is disposed on the upper surface of the base so as to cover the edge of the semiconductor substrate while exposing the exposed portion including the detection portion and the groove in a plan view.

[0004] Japanese Patent Application Laid-Open No. 2017-227451

[0005] In the manufacturing process of the sensor, the coating resin is formed by pouring uncured resin between a base on which the semiconductor substrate is provided and a mold placed on the base. At this time, part of the mold comes into contact with the exposed portion of the semiconductor substrate, thereby preventing the resin from reaching the exposed portion.

[0006] On the other hand, to prevent damage to the exposed portion due to contact with the mold, a film may be applied to the surface of the mold facing the base. In this case, the film, rather than the mold itself, contacts the exposed portion of the semiconductor substrate. This manufacturing process using such a film is known as the Film Assisted Molding (FAM) process.

[0007] When forming a coating resin using the FAM process, depending on the inflow pressure of the resin and the pressure applied to the base of the mold, uncured resin may enter the gap between the exposed portion and the film. In the sensor, the resin that enters the gap reaches the groove before the detection portion and remains there. In this way, the sensor described in Patent Document 1 aims to prevent the resin from reaching the detection portion.

[0008] However, in the sensor described in Patent Document 1, while low-fluidity substances in the resin fall into the groove, high-fluidity substances in the resin may flow along the surface of the film and pass across the groove. As a result, the high-fluidity substances may reach the detection unit. If the high-fluidity substances adhere to the detection unit, the measurement operation of the detection unit is hindered, and the sensor characteristics are deteriorated. In other words, there is still room for improvement in terms of preventing uncured resin from reaching the detection unit.

[0009] Therefore, an object of the present disclosure is to solve the above-mentioned problem and to provide a pressure sensor that can prevent uncured resin from reaching a detection portion.

[0010] a detection element provided on an upper surface of the substrate for detecting pressure; and a coating resin provided on the upper surface of the substrate for covering a portion of the detection element, wherein the coating resin has a coating recess recessed downward from the upper surface of the coating resin and exposing at least a portion of the upper surface of the detection element, and the detection element has: a detection portion on which pressure acts and provided in a portion of the upper surface of the element exposed by the coating recess; a groove recessed downward from the upper surface of the element and surrounding the detection portion in a plan view seen from above; and an inner recess provided between the groove and the detection portion in the plan view, continuous with the groove, and recessed downward to be shallower than the groove; and the groove has an outer surface and an inner surface facing the outer surface and located closer to the detection portion than the outer surface in the plan view, The inner recess has a side surface extending downward from the upper surface of the element, and a bottom surface extending from the lower edge of the side surface of the inner recess toward the outer surface and connecting the side surface of the inner recess to the inner surface of the groove.

[0011] According to the present disclosure, it is possible to provide a pressure sensor that can prevent uncured resin from reaching a detection portion.

[0012] FIG. 6 is a plan view of a pressure sensor according to a first embodiment of the present disclosure. FIG. 7 is a cross-sectional view taken along line A1-A1 of FIG. 1. FIG. 8 is a plan view of a detection element provided in the pressure sensor of FIG. 1. FIG. 9 is an enlarged cross-sectional view showing area Z1 of FIG. 2. FIG. 10 is an enlarged cross-sectional view showing area Z2 of FIG. 4. FIG. 11 is a cross-sectional view showing an example of a manufacturing process for the pressure sensor of FIG. 1. FIG. 12 is an enlarged cross-sectional view showing area Z3 of FIG. 6. FIG. 13 is an enlarged cross-sectional view corresponding to FIG. 4 of a pressure sensor according to a second embodiment of the present disclosure. FIG. 14 is an enlarged cross-sectional view corresponding to FIG. 4 of a pressure sensor according to a third embodiment of the present disclosure. FIG. 15 is a cross-sectional view of a pressure sensor according to a fourth embodiment of the present disclosure. FIG. 16 is a plan view showing the top surface of an element in a pressure sensor according to the fourth embodiment of the present disclosure.

[0013] According to a first aspect of the present disclosure, there is provided a substrate; a detection element provided on an upper surface of the substrate for detecting pressure; and a coating resin provided on the upper surface of the substrate for covering a portion of the detection element, wherein the coating resin has a coating recess recessed downward from the upper surface of the coating resin and exposing at least a portion of the upper surface of the detection element, and the detection element has: a detection portion provided on a portion of the upper surface of the element exposed by the coating recess and on which pressure acts; a groove recessed downward from the upper surface of the element and surrounding the detection portion in a plan view seen from the top to bottom direction; and an inner recess provided between the groove and the detection portion in the plan view, continuous with the groove, and recessed downward to be shallower than the groove, and the groove has an outer surface and an inner surface facing the outer surface and positioned closer to the detection portion than the outer surface in the plan view, The pressure sensor provides a pressure sensor in which the inner recess has a side surface extending downward from the upper surface of the element, and a bottom surface extending from a lower edge of the side surface of the inner recess toward the outer surface and connecting the side surface of the inner recess with the inner surface of the groove.

[0014] According to a second aspect of the present disclosure, there is provided the pressure sensor according to the first aspect, wherein the inner recess has a plurality of protrusions arranged on a side surface of the inner recess in the vertical direction.

[0015] According to a third aspect of the present disclosure, there is provided a pressure sensor as described in the first or second aspect, wherein the height of the side surface of the inner recess is smaller than the length between the lower edge of the side surface of the inner recess at the bottom surface of the inner recess and the upper edge of the inner surface of the groove.

[0016] According to a fourth aspect of the present disclosure, there is provided a pressure sensor described in any one of the first to third aspects, wherein the length between the lower edge of the side of the inner recess at the bottom surface of the inner recess and the upper edge of the inner side of the groove is smaller than the distance between the upper edge of the side of the inner recess at the top surface of the element and the detection portion.

[0017] According to a fifth aspect of the present disclosure, there is provided a pressure sensor described in any one of the first to fourth aspects, wherein the detection element further has an outer recess portion that is provided continuously with the outer surface of the groove portion in the planar view and is recessed downward to a shallower depth than the groove portion.

[0018] According to a sixth aspect of the present disclosure, there is provided a pressure sensor as described in the fifth aspect, in which the outer recess has a side extending downward from the upper surface of the element, a bottom surface extending from the lower edge of the side of the outer recess toward the inner surface of the groove and connecting the side of the outer recess with the outer surface of the groove, and a plurality of protrusions aligned in the vertical direction on the side of the outer recess.

[0019] According to a seventh aspect of the present disclosure, there is provided a pressure sensor according to any one of the first to sixth aspects, wherein the inner recess has a plurality of protrusions provided on a bottom surface of the inner recess and aligned in a direction from the inner surface of the groove toward the side surface of the inner recess in the plan view, and the height of each protrusion is smaller than the depth of the inner recess.

[0020] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following description, terms indicating specific directions or positions (e.g., terms including "up," "down," "right," and "left") will be used as necessary. However, the use of these terms 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. Furthermore, the following description is merely exemplary in nature and is not intended to limit the present disclosure, its applications, or its uses. Furthermore, the drawings are schematic, and the ratios of the dimensions and the like do not necessarily correspond to reality.

[0021] In this specification, "electrically connected" includes the ability to conduct current between multiple components, multiple components being capacitively coupled, and multiple components being electromagnetically coupled.

[0022] <First embodiment> A pressure sensor according to a first embodiment of the present disclosure will be described with reference to Figures 1 and 2. Figure 1 is a plan view of the pressure sensor according to the first embodiment of the present disclosure. Figure 2 is a cross-sectional view taken along line A1-A1 in Figure 1.

[0023] 1 and 2, the pressure sensor 1 according to the first embodiment includes a substrate 2, a detection element 3 provided on the substrate 2, and a coating resin 4 provided on the substrate 2 so as to cover the detection element 3. For example, the pressure sensor 1 is configured to be able to measure pressures such as absolute pressure, gauge pressure, differential pressure, and airflow pressure.

[0024] As shown in Fig. 2, the substrate 2 has a lower surface 2a and an upper surface 2b opposite to the lower surface 2a. For example, the substrate 2 is a wiring substrate such as a resin substrate, a ceramic substrate, or a lead frame. In this embodiment, the substrate 2 is a printed wiring board. In the example shown in Fig. 1, the substrate 2 is a square in a plan view from the top-bottom direction, having sides extending in two directions that intersect with each other and that intersect with the top-bottom direction.

[0025] As shown in FIG. 2 , a detection element 3 and a circuit element 21 are provided on the upper surface 2 b of the substrate 2. The detection element 3 is a pressure sensor element that detects pressure. For example, the detection element 3 is a piezo-resistive or capacitive pressure sensor element, and is a MEMS (Micro Electro Mechanical Systems) element. In this embodiment, the detection element 3 is a rectangular parallelepiped and has an element lower surface 3 a facing the upper surface 2 b of the substrate 2 and an element upper surface 3 b opposite the element lower surface 3 a. The detection element 3 has a detection unit 31 that is provided on the element upper surface 3 b and is subjected to pressure. For example, the detection unit 31 is a membrane or diaphragm that receives pressure.

[0026] Fig. 3 is a plan view of the detection element provided in the pressure sensor of Fig. 1. As shown in Fig. 3, the detection portion 31 is located on the element upper surface 3b at a distance from the edge of the element upper surface 3b. In plan view, the detection portion 31 has a rotationally symmetric shape centered on a virtual central axis VA1 extending in the up-down direction. In this embodiment, the detection portion 31 is rectangular in plan view.

[0027] As shown in Figures 2 and 3, the detection element 3 has a groove portion 32 and an inner recess portion 33 recessed downward in the vertical direction from the element upper surface 3b. The groove portion 32 and the inner recess portion 33 surround the detection portion 31 in a plan view. In this embodiment, the groove portion 32 and the inner recess portion 33 are rectangular with no discontinuities in a plan view. The inner recess portion 33 is provided between the detection portion 31 and the groove portion 32 and is continuous with the groove portion 32. In other words, the extension direction of the groove portion 32 coincides with the extension direction of the inner recess portion 33. In this embodiment, the extension direction is along the four sides of the rectangle. The detailed configurations of the groove portion 32 and the inner recess portion 33 will be described later.

[0028] In the following description, the direction intersecting both the up-and-down direction and the extension direction of groove portion 32 will also be simply referred to as the "intersecting direction." In addition, in the intersecting direction, the direction approaching detection portion 31 will also be referred to as the "inward direction," and the direction away from detection portion 31 will also be referred to as the "outward direction." In addition, a cross section intersecting the extension direction of groove portion 32 or inner recess portion 33 (see FIG. 4) will also be simply referred to as the "cross section of groove portion 32 or inner recess portion 33."

[0029] The circuit element 21 is, for example, an element including an application specific integrated circuit (ASIC). In this embodiment, the circuit element 21 includes a converter that converts the voltage signal output from the detection element 3 into a digital signal, a filter that filters the digital signal from the converter, a temperature sensor that detects temperature, a processor that corrects the filtered digital signal based on the temperature detected by the temperature sensor, and a memory that stores correction coefficients and the like used when correcting the digital signal using the detected temperature.

[0030] 2, the detection element 3 and the circuit element 21 are arranged side by side on the upper surface 2b of the substrate 2. For example, the detection element 3 and the circuit element 21 are each bonded to the substrate 2 via an adhesive member such as a die attach film or a die bond material.

[0031] In this embodiment, the detection element 3 and the circuit element 21 are connected via a bonding wire 22. Furthermore, the circuit element 21 and the substrate 2 are connected via a bonding wire 23. As a result, the circuit provided on the substrate 2, the detection element 3, and the circuit element 21 are electrically connected.

[0032] The detection element 3 and the circuit element 21 may be electrically connected via a circuit on the substrate 2. For example, the detection element 3 and the circuit element 21 may each be connected to the circuit on the substrate 2 via a bonding wire or a bump. The detection element 3 and the circuit element 21 may also be arranged one above the other in the vertical direction on the substrate 2.

[0033] The coating resin 4 is provided on the upper surface 2b of the substrate 2 and covers a portion of the detection element 3, the circuit element 21, and the bonding wires 22 and 23. The coating resin 4 has a main body 41 provided on the upper surface 2b of the substrate 2 and a coating protrusion 42 protruding upward in the vertical direction from the main body 41. The main body 41 has a lower surface 41a facing the substrate 2 and an upper surface 41b opposite the lower surface 41a. The coating protrusion 42 protrudes from the upper surface 41b of the main body 41. The main body 41 and the coating protrusion 42 are integrally molded as described below. For example, the coating resin 4 is made of epoxy resin, unsaturated polyester resin, or phenolic resin. In FIG. 2, the boundary between the main body 41 and the coating protrusion 42 is indicated by a dashed line.

[0034] 1 and 2, the main body 41 is a rectangular parallelepiped and is provided on the entire upper surface 2b of the substrate 2.

[0035] The coating convex portion 42 has a truncated cone shape that tapers upward in the vertical direction. The coating convex portion 42 has an upper surface 42a that is the top surface, and an outer wall surface 42b that connects the upper surface 42a to the upper surface 41b of the main body 41. The upper surface 42a of the coating convex portion 42 constitutes a part of the upper surface of the coating resin 4.

[0036] An O-ring 6 may be provided on the upper surface 41b of the main body 41 so as to surround the covering protrusion 42 in a plan view. For example, the O-ring 6 is made of an elastic material such as rubber or silicone. The O-ring 6 may be provided around the covering protrusion 42 in a stretched state and may contact the outer wall surface 42b of the covering protrusion 42. In this case, when the pressure sensor 1 is attached to an electronic device, the O-ring 6 is crushed and elastically deformed between the housing of the electronic component and the pressure sensor 1, and may prevent moisture from flowing between them.

[0037] The coating resin 4 is provided with a coating recess 5 that is recessed downward in the vertical direction from the upper surface 42a of the coating protrusion 42 and exposes a part of the detection element 3. In the example shown in Fig. 1, the coating recess 5 exposes the detection section 31, groove 32, and inner recess 33 of the detection element 3. In other words, the coating resin 4 covers the detection element 3 except for the coating recess 5.

[0038] 2, in this embodiment, the coated recess 5 has a tapered shape in which the opening surface becomes smaller in the vertical direction as it moves away from the upper surface 42a of the coated protrusion 42. In this embodiment, the coated recess 5 has a rotationally symmetric shape about an imaginary central axis VA1 extending along the vertical direction. As shown in FIG. 1, the shape of the opening surface of the coated recess 5 is a substantially rectangular shape with rounded corners in a plan view.

[0039] The covering recess 5 has a bottom surface 5 a where the detection element 3 is exposed, and an inner wall surface 5 b connecting the bottom surface 5 a and the upper surface 42 a of the covering protrusion 42 .

[0040] The configurations of the groove portion 32 and the inner recess portion 33 will be described with reference to Figures 4 and 5. Figure 4 is an enlarged cross-sectional view showing area Z1 in Figure 2. Figure 5 is an enlarged cross-sectional view showing area Z2 in Figure 4. In Figure 4, the boundary between the groove portion 32 and the inner recess portion 33 is indicated by a dashed line.

[0041] The groove 32 and the inner recess 33 are configured to be rotationally symmetrical about the imaginary central axis VA1, and therefore, the groove 32 and the inner recess 33 have a cross section similar to the cross section shown in FIG.

[0042] 4, the groove 32 has a bottom surface 32a that intersects the vertical direction and two side surfaces (an outer surface 32b and an inner surface 32c) that extend along the vertical direction. In a cross section of the groove 32, the width W1 of the bottom surface 32a in the intersecting direction is, for example, 10 μm.

[0043] The outer surface 32b is the outermost of the two side surfaces and connects the bottom surface 32a to a region on the top surface 3b of the element that is outer than the groove 32. The inner surface 32c is the side surface that is inner than the outer surface 32b in a plan view and faces the outer surface 32b in the intersecting direction. In this embodiment, the depth D1 of the groove 32 from the top surface 3b of the element is 100 μm.

[0044] The inner recess 33 is provided inside the groove 32 and is continuous with the groove 32. The inner recess 33 is recessed downward from the upper surface 3b of the element to a shallower depth than the groove 32. In this embodiment, the depth D2 of the inner recess 33 from the upper surface 3b of the element is 4 μm.

[0045] The inner recess 33 has a bottom surface 33a that intersects the vertical direction, and a side surface 33b that connects the bottom surface 33a and the element upper surface 3b along the vertical direction.

[0046] The configuration of the bottom surface 33a and side surface 33b of the inner recess will be described with reference to Fig. 5. Fig. 5 is an enlarged cross-sectional view showing area Z2 in Fig. 4.

[0047] The bottom surface 33a of the inner recess connects the inner surface 32c of the groove to the side surface 33b of the inner recess. That is, the inner surface 32c of the groove connects the bottom surface 32a of the groove to the bottom surface 33a of the inner recess. That is, the bottom surface 33a extends from the lower edge of the side surface 33b of the inner recess toward the outer surface 32b of the groove. In the example shown in Figure 5, the bottom surface 33a of the inner recess is perpendicular to the up-down direction.

[0048] The bottom surface 33a has a width W2 in the transverse direction in the cross section of the inner recess 33. For example, the width W2 of the bottom surface 33a is the length between the lower edge of the side surface 33b of the inner recess and the upper edge of the inner side surface 32c of the groove at the bottom surface 33a. As shown in FIG. 4 , the width W2 of the bottom surface 33a is smaller than the distance L1 between the upper edge of the side surface 33b of the inner recess and the detection unit 31 at the element upper surface 3b. In this embodiment, the width W2 of the bottom surface 33a is 5 μm, smaller than the width W1 of the bottom surface 32a of the groove.

[0049] As shown in FIG. 5 , in this embodiment, the side surface 33b of the recess extends downward from the upper surface 3b of the element and reaches the inner edge of the bottom surface 33a. The height H1 of the side surface 33b in the vertical direction is smaller than the width W2 of the bottom surface 33a of the recess in the intersecting direction. That is, the height H1 of the side surface 33b is smaller than the length, at the bottom surface 33a of the recess, between the lower edge of the side surface 33b of the recess and the upper edge of the inner side surface 32c of the groove. In this embodiment, because the bottom surface 33a is perpendicular to the vertical direction, the height H1 of the side surface 33b is equal to the depth D2 of the recess 33. That is, the height H1 of the side surface 33b is 4 μm.

[0050] The inner recess 33 has a plurality of convex portions 331 provided on the bottom surface 33a and a plurality of protruding portions 332 provided on the side surface 33b.

[0051] On the bottom surface 33a, the multiple protrusions 331 are aligned in the intersecting direction. In the present embodiment, each protrusion 331 is linearly arranged in a plan view along the extension direction of the inner recess 33. The multiple protrusions 331 are aligned in a direction from the inner side surface 32c of the groove toward the side surface 33b of the inner recess 33 in a plan view.

[0052] In this embodiment, the plurality of protrusions 331 are provided across the entire bottom surface 33a of the inner recess in the cross direction. That is, the bottom surface 33a of the inner recess is an uneven surface in which the plurality of protrusions 331 and the recesses formed between them are repeated in the cross direction.

[0053] Each of the protrusions 331 has a height H2 from the bottom surface 33a of the inner recess 33 to the top of the protrusion 331. The height H2 is smaller than the depth D2 of the inner recess 33. Therefore, the top of each of the protrusions 331 is located below the opening surface of the inner recess 33. The heights H2 of the protrusions 331 may be the same as or different from each other. In this embodiment, the heights H2 of the protrusions 331 are the same as each other, that is, 1 μm.

[0054] On the side surface 33b, the multiple protrusions 332 are aligned in the vertical direction. In this embodiment, each protrusion 332 is provided linearly along the extension direction of the inner recess 33. The multiple protrusions 332 are provided across the entire side surface 33b of the inner recess in the vertical direction. In other words, the side surface 33b of the inner recess is an uneven surface in which the multiple protrusions 332 and the recesses formed between them are repeated in the intersecting direction.

[0055] Each protrusion 332 has a height H3 from the side surface 33b of the inner recess to the top of the protrusion 332. The heights H3 of the protrusions 332 may be the same as or different from each other. For example, the heights H3 of the protrusions 332 are the same as each other and are equal to or less than 1 μm.

[0056] As shown in Fig. 4, the groove 32 in this embodiment has a plurality of protrusions 322 that are positioned in a row on the inner surface 32c downward from the upper edge of the inner surface 32c and each protrude from the inner surface 32c. The plurality of protrusions 322 may be provided over the entire inner surface 32c of the groove in the vertical direction, or may be provided only on a portion in the vertical direction. In the example shown in Fig. 4, the plurality of protrusions 322 are provided only in the upper region of the inner surface 32c. Here, the upper region includes the upper edge of the inner surface 32c.

[0057] 5, each protrusion 322 has a height H4 from the inner surface 32c of the groove to the top of the protrusion 322. The heights H4 of the protrusions 322 may be the same as or different from each other. For example, the heights H4 of the protrusions 322 are the same as each other and are equal to or less than 1 μm.

[0058] <Method of Forming Coating Resin> A FAM process, which is an example of a method of forming the coating resin 4 in the pressure sensor 1, will be described with reference to Fig. 6. Fig. 6 is a cross-sectional view showing an example of a manufacturing process for the pressure sensor of Fig. 1.

[0059] In this process, the coating resin 4 is formed using two molds: a lower mold 101 and an upper mold 102. In the process of forming the coating resin 4, an aggregate substrate in which a large number of substrates 2 are arranged in the surface direction is placed on the lower mold 101. Figure 6 shows a portion of the aggregate substrate that corresponds to one pressure sensor 1. The substrate 2 on the lower mold 101 is provided with a detection element 3, a circuit element 21, bonding wires 22, 23, etc.

[0060] The upper mold 102 has a lower surface 102a that faces the lower mold 101 in the vertical direction. The lower surface 102a has a shape corresponding to the shape of the coating resin 4.

[0061] A film 103 is provided on the lower surface 102a to prevent the resin from adhering to the upper mold 102 and damage to the detection element 3. For example, the film 103 is a release film containing Teflon (registered trademark).

[0062] The film 103 is heated through the upper mold 102 and is sucked toward the lower surface 102a through suction holes (not shown) opened in the lower surface 102a of the upper mold 102. The film 103 becomes more flexible by being heated than before heating, and is formed into a shape that conforms to the lower surface 102a by the suction.

[0063] The upper mold 102 is fixed to the lower mold 101 so as to sandwich the substrate 2 between the upper mold 102 and the lower mold 101. At this time, the film 103 contacts the area of ​​the element upper surface 3b that is exposed by the covering recess 5. Specifically, the film 103 contacts the detection portion 31, the groove portion 32, and the inner recess portion 33.

[0064] 7 is an enlarged cross-sectional view showing region Z3 in FIG. 6. As shown in FIG. 7, the flexible film 103 is pressed downward by the upper mold 102 (see FIG. 6) and enters part of the groove 32 and the inner recess 33. At this time, the film 103 enters the recessed portions between the multiple protrusions 322 in the groove 32, as well as the recessed portions between the multiple convex portions 331 and the recessed portions between the multiple protrusions 332 in the inner recess 33. This improves the adhesion of the film 103 to the inner side surface 32c of the groove and the bottom surface 33a and side surface 33b of the inner recess. In other words, the adhesion of the film 103 to the detection element 3 is improved.

[0065] Furthermore, each protrusion 322 of the groove 32 and each protrusion 332 of the inner recess 33 prevents the film 103 from moving upward when it enters the recess directly below the protrusion. This makes it possible to more reliably maintain the tight contact between the film 103 and the detection element 3 even when an upward pulling force is unintentionally applied to the film 103.

[0066] The resin that constitutes the coating resin 4 is poured in an uncured state into the space SP1 (see FIG. 6) between the substrate 2 and the film 103. At this time, depending on conditions such as the contact pressure of the film 103 against the detection element 3 and the inflow pressure of the resin into the space SP1, the resin may enter the interface S1 between the film 103 and the detection element 3. The resin progresses inward along the interface S1.

[0067] In the example shown in Figure 7, the resin advances to the right along interface S1. The resin that has entered interface S1 reaches groove 32 before reaching detection unit 31. In groove 32, substances with low fluidity in the resin (hereinafter also referred to as "low fluidity substances") leave surface 103a of film 103 and fall into groove 32. This prevents the low fluidity substances from reaching detection unit 31. On the other hand, substances with high fluidity in the resin (hereinafter also referred to as "high fluidity substances") move along surface 103a of the film due to surface tension and move further inward so as to approach detection unit 31.

[0068] Here, the inner surface 32c of the groove and the side surface 33b of the inner depression function as a barrier against the highly fluid substance moving inward. The highly fluid substance moving along the surface 103a of the film first hits the inner surface 32c of the groove as shown by the arrow in Figure 7. At this time, the inward force of the highly fluid substance (the force toward the right in Figure 7) is reduced.

[0069] Furthermore, the inner side surface 32c of the groove and the bottom surface 33a of the inner recess are firmly adhered to the film 103 due to the presence of the protrusions 322 and the projections 331. This prevents the highly fluid substance from entering the interface S1 or progressing inward along the interface S1.

[0070] Furthermore, unlike conventional sensors (for example, the sensor described in Patent Document 1), the highly fluid substance also strikes the side surface 33b of the inner recess as shown by the arrow in Fig. 7. This further reduces the inward force of the highly fluid substance (the force toward the right in Fig. 7).

[0071] Furthermore, like the inner surface 32c of the groove and the bottom surface 33a of the inner recess, the side surface 33b of the inner recess is also firmly adhered to the film 103 due to the presence of the protrusion 332. This further prevents the highly fluid substance from progressing inward along the interface S1. Therefore, in the pressure sensor 1, compared to conventional sensors, the possibility that resin containing a highly fluid substance will reach the detection section during the formation of the coating resin 4 can be reduced.

[0072] According to the pressure sensor 1 of the first embodiment, an inner recess 33, which is recessed downward and shallower than the groove 32, is provided between the groove 32 and the detection section 31 and is continuous with the groove 32. In this configuration, when the coating resin 4 is formed, the highly fluid substance that moves inward along the surface 103a of the film impinges not only on the inner side surface 32c of the groove but also on the side surface 33b of the inner recess. This makes it possible to suppress the highly fluid substance from moving inward.

[0073] Furthermore, by providing the inner recess 33 that is continuous with the groove 32 in the intersecting direction, the flexible film 103 can penetrate deeper into the groove 32 compared to a configuration without the inner recess 33. This improves the adhesion between the film 103 and the detection element 3. This makes it possible to prevent the highly fluid substance from penetrating the interface S1 between the film 103 and the detection element 3 or from progressing inward along the interface S1.

[0074] Therefore, it is possible to prevent uncured resin from reaching the detection portion 31 .

[0075] Furthermore, in the pressure sensor 1 according to the first embodiment, the inner recess 33 has a plurality of protrusions 332 aligned in the vertical direction on the side surface 33b. With this configuration, the film 103 enters the recessed portions between the protrusions 332 during the process of forming the coating resin 4. Therefore, the adhesion between the film 103 and the side surface 33b of the inner recess is improved compared to a configuration in which the protrusions 332 are not provided.

[0076] Furthermore, each protrusion 332 prevents upward movement of film 103 located in the recessed portion directly below that protrusion 332. This makes it possible to more reliably maintain the tight contact between film 103 and side surface 33b of the inner recessed portion even when a force pulling film 103 upward is unintentionally applied.

[0077] Furthermore, by providing the protrusion 332, the length of the interface S1 from the inner surface 32c of the groove to the detection unit 31 is increased in the cross section of the groove 32 and the inner recess 33. This makes it more difficult for uncured resin to reach the detection unit 31. Therefore, it is possible to further prevent uncured resin from reaching the detection unit 31.

[0078] Furthermore, in the pressure sensor 1 according to the first embodiment, the height H1 of the side surface 33b of the recess is smaller than the width W2 of the bottom surface 33a of the recess in the intersecting direction. With this configuration, the film 103 is more likely to come into contact with the bottom surface 33a of the recess in the vertical direction than in a configuration in which the height H1 is larger than the width W2. This improves the adhesion between the film 103 and the bottom surface 33a of the recess, further preventing uncured resin from reaching the detection unit 31.

[0079] Furthermore, in the pressure sensor 1 according to the first embodiment, the width W2 of the bottom surface 33a of the inner recess in the intersecting direction is smaller than the distance L1 on the element upper surface 3b between the side surface 33b of the inner recess and the detection unit 31. With this configuration, the distance between the inner recess 33 on the element upper surface 3b and the detection unit 31 is larger than in a configuration in which the width W2 is larger than the distance L1, and therefore it is possible to further prevent uncured resin from reaching the detection unit 31.

[0080] Furthermore, in the pressure sensor 1 according to the first embodiment, the inner recess 33 has a plurality of protrusions 331 arranged in a cross direction on the bottom surface 33a. With this configuration, the film 103 enters the recesses between the protrusions 331 during the coating resin 4 formation process. This improves adhesion between the film 103 and the bottom surface 33a of the inner recess compared to a configuration in which the protrusions 331 are not provided. This further prevents uncured resin from reaching the detection unit 31.

[0081] Second Embodiment A pressure sensor according to a second embodiment of the present disclosure will be described with reference to Fig. 8. Fig. 8 is an enlarged cross-sectional view of the pressure sensor according to the second embodiment of the present disclosure, corresponding to Fig. 4.

[0082] The pressure sensor 1A according to the second embodiment differs from the pressure sensor 1 according to the first embodiment in that an outer recess 34 is provided in the detection element 3. In the following description of the second embodiment, the same components as those in the pressure sensor 1 are denoted by the same reference numerals and description thereof will be omitted.

[0083] As shown in Fig. 8, in the pressure sensor 1A, the detection element 3 further has an outer recess 34 that is recessed downward and shallower than the groove 32. In Fig. 8, the boundaries between the groove 32, the inner recess 33, and the outer recess 34 are each indicated by a dashed line. In plan view, the outer recess 34 is provided outward from the groove 32 in the intersecting direction and continuous with the groove 32. That is, in plan view, the outer recess 34 is provided continuous with the outer surface 32b of the groove. That is, the outer recess 34 is provided continuous with the groove 32 on the opposite side from the inner recess 33 in the intersecting direction.

[0084] In this embodiment, the groove portion 32, the inner recessed portion 33, and the outer recessed portion 34 are configured to be rotationally symmetrical about the imaginary central axis VA1 (see FIG. 3). Therefore, the groove portion 32, the inner recessed portion 33, and the outer recessed portion 34 have a cross section similar to the cross section shown in FIG. 8 over the entire circumference. The extension direction of the outer recessed portion 34 coincides with the extension directions of the groove portion 32 and the inner recessed portion 33.

[0085] The depth D3 of the outer recess 34 from the element top surface 3b is smaller than the depth D1 of the groove 32. The depth D3 of the outer recess 34 may be the same as or different from the depth D2 of the inner recess 33. In this embodiment, the depth D3 of the outer recess 34 is 4 μm, the same as the depth D3 of the inner recess 33.

[0086] The outer recess 34 has a bottom surface 34a that intersects the vertical direction and a side surface 34b that extends along the vertical direction and connects the bottom surface 34a to the element's top surface 3b. The side surface 34b extends downward from a region on the element's top surface 3b outside the outer recess 34. The bottom surface 34a connects the side surface 34b to the outer surface 32b of the groove along the intersecting direction. In the example shown in FIG. 8 , the bottom surface 34a is perpendicular to the vertical direction. Therefore, the height H5 of the side surface 34b in the vertical direction is 4 μm, the same as the depth D3 of the outer recess 34.

[0087] Similar to the inner recess 33, the outer recess 34 has a plurality of convex portions 341 provided on the bottom surface 34a and a plurality of protruding portions 342 provided on the side surface 34b.

[0088] The plurality of protrusions 341 extend linearly on the bottom surface 34a along the extension direction of the outer recess 34, and are aligned in the intersecting direction. The top of each protrusion 341 is located below the element upper surface 3b.

[0089] The multiple protrusions 342 are positioned side by side in the up-down direction on the side surface 34b. In this embodiment, each protrusion 342 is provided linearly along the extension direction of the outer recess 34. The multiple protrusions 342 are provided across the entire side surface 34b of the outer recess in the up-down direction. In other words, the side surface 34b of the outer recess is formed as an uneven surface in which the multiple protrusions 342 and the recesses formed between them are repeated in the up-down direction.

[0090] According to the pressure sensor 1A of the second embodiment, an outer recess 34, which is recessed downward and shallower than the groove 32, is provided continuous with the outer surface 32b of the groove in the cross direction. With this configuration, compared to a configuration in which the outer recess 34 is not provided, the flexible film 103 can penetrate deeper into the groove 32 when forming the coating resin 4. This improves the adhesion between the film 103 and the detection element 3. This makes it possible to prevent highly fluid substances from penetrating the interface S1 between the film 103 and the detection element 3 or from progressing inward along the interface S1.

[0091] Furthermore, in the pressure sensor 1A according to the second embodiment, the outer recess 34 has a plurality of protrusions 342 aligned in the vertical direction on the side surface 34b. With this configuration, the film 103 enters the recessed portions between the protrusions 342 during the process of forming the coating resin 4. Therefore, the adhesion between the film 103 and the side surface 34b of the outer recess is improved compared to a configuration in which the protrusions 342 are not provided.

[0092] Furthermore, each protrusion 342 prevents upward movement of the film 103 located in the recessed portion directly below the protrusion 342. This makes it possible to more reliably maintain the tight contact between the film 103 and the side surface 34b of the outer recessed portion even when a force pulling the film 103 upward is unintentionally applied.

[0093] Furthermore, by providing the protrusion 342, the length of the interface S1 between the film 103 and the detection element 3 is increased in the cross sections of the groove 32, the inner recess 33, and the outer recess 34. This makes it more difficult for uncured resin to reach the detection unit 31. Therefore, it is possible to further prevent uncured resin from reaching the detection unit 31.

[0094] Third Embodiment A pressure sensor according to a third embodiment of the present disclosure will be described with reference to Fig. 9. Fig. 9 is an enlarged cross-sectional view of the pressure sensor according to the third embodiment of the present disclosure, corresponding to Fig. 4.

[0095] The pressure sensor 1B according to the third embodiment differs from the pressure sensor 1 according to the first embodiment in that a second inner recess 35 is provided in the detection element 3. In the following description of the third embodiment, the same components as those in the pressure sensor 1 will be given the same reference numerals and the description thereof may be omitted.

[0096] 9, in the pressure sensor 1B, the detection element 3 has a first inner recess 33 and a second inner recess 35. The first inner recess 33 corresponds to the inner recess 33 in the pressure sensor 1 according to the first embodiment.

[0097] The second inner recess 35 is provided between the groove 32 and the first inner recess 33 in the intersecting direction, continuing into both the groove 32 and the first inner recess 33, and is recessed downward from the element top surface 3b. In Figure 9, the boundaries between the groove 32, the first inner recess 33, and the second inner recess 35 are each indicated by a dashed line.

[0098] In this embodiment, the groove 32, the first inner recess 33, and the second inner recess 35 are configured to be rotationally symmetrical about the imaginary central axis VA1 (see FIG. 3 ). Therefore, the groove 32, the first inner recess 33, and the second inner recess 35 have a cross section similar to the cross section shown in FIG. 9 over the entire circumference. The extension direction of the second inner recess 35 coincides with the extension direction of the groove 32 and the first inner recess 33.

[0099] 9, the depth D4 of the second inner recess 35 from the element top surface 3b is smaller than the depth D1 of the groove 32 and larger than the depth D2 of the first inner recess 33. As a result, the groove 32, the second inner recess 35, and the first inner recess 33 are formed in a stepped shape that rises inward in the intersecting direction. In this embodiment, the depth D4 of the second inner recess 35 is 8 μm.

[0100] The second inner recess 35 has a bottom surface 35a that intersects the vertical direction and a side surface 35b that extends along the vertical direction and connects the bottom surface 35a to the bottom surface 33a of the first inner recess 35. The bottom surface 35a connects the side surface 35b to the inner surface 32c of the groove along the intersecting direction.

[0101] Here, the bottom surface 33a of the first inner recess connects the side surface 33b of the first inner recess to the inner side surface 32c of the groove via the bottom surface 35a and side surface 35b of the second inner recess.

[0102] Similar to the first internal recess 33, the second internal recess 35 has a plurality of convex portions 351 provided on the bottom surface 35a and a plurality of protruding portions 352 provided on the side surface 35b. The plurality of convex portions 351 correspond to the plurality of convex portions 331 in the first internal recess 33. The plurality of protruding portions 352 correspond to the plurality of protruding portions 332 in the first internal recess 33.

[0103] According to the pressure sensor 1B of the third embodiment, a second inner recess 35 is provided between the groove 32 and the first inner recess 33 in the cross direction. In this configuration, when the coating resin 4 is formed, the highly fluid substance that moves inward along the film 103 impinges on the inner side surface 32c of the groove and the side surface 33b of the first inner recess, as well as the side surface 35b of the second inner recess. This further suppresses the highly fluid substance from moving inward.

[0104] Furthermore, compared to a configuration in which the second inner recess 35 is not provided, the flexible film 103 can penetrate deeper into the groove 32. This further improves the adhesion between the film 103 and the detection element 3. This further prevents the highly fluid substance from penetrating the interface S1 between the film 103 and the detection element 3 or from progressing inward along the interface S1.

[0105] Therefore, it is possible to further prevent uncured resin from reaching the detection portion 31 .

[0106] <Fourth embodiment> A pressure sensor according to a fourth embodiment of the present disclosure will be described using Fig. 10 and Fig. 11. Fig. 10 is a cross-sectional view of the pressure sensor according to the fourth embodiment of the present disclosure. Note that Fig. 10 shows an enlarged view of the detection unit 31 and its surroundings. Fig. 11 is a plan view showing the upper surface of the element in the pressure sensor according to the fourth embodiment of the present disclosure.

[0107] The pressure sensor 1C according to the fourth embodiment differs from the pressure sensor 1B according to the third embodiment in that there are gaps in the groove portion 32, the inner recess portion 33, and the outer recess portion 34. In the following description of the fourth embodiment, the same reference numerals are used to designate the same components as those in the pressure sensor 1B, and the description thereof may be omitted.

[0108] 10 , the element upper surface 3b of the detection element 3 has an exposed region 36 exposed from the coating resin 4 in the coating recess 5. The exposed region 36 is provided with a detection portion 31, and a groove portion 32, an inner recess portion 33, and an outer recess portion 34 that surround the detection portion 31 in a plan view.

[0109] 11 , the detection unit 31 and the exposed area 36 are rectangular in shape with intersecting sides extending in the left-right and depth directions in a plan view, while the groove 32, the inner recess 33, and the outer recess 34 are substantially rectangular in shape with intersecting sides extending in the left-right and depth directions in a plan view.

[0110] The exposed region 36 has a right region 361 that is a region to the right of the detection unit 31 in the left-right direction, and a left region 362 that is a region to the left of the detection unit 31 in the left-right direction. In addition, the exposed region 36 has a rear region 363 that is a region behind the detection unit 31 in the depth direction, and a front region 364 that is a region in front of the detection unit 31. In the following description, the right region 361, the left region 362, the rear region 363, and the front region 364 may be collectively referred to as four regions 361 to 364.

[0111] For example, the right region 361 is the region to the right of the right side of the detection unit 31 in a planar view and its imaginary extension. The left region 362 is the region to the left of the left side of the detection unit 31 in a planar view and its imaginary extension. The back region 363 is the region behind the back side of the detection unit 31 in a planar view and its imaginary extension. The front region 364 is the region in front of the front side of the detection unit 31 in a planar view and its imaginary extension.

[0112] 11 shows distances L11 to L14 between the detection unit 31 and the outer edge of the exposed region 36 in four regions 361 to 364. Distance L11 is the distance between the detection unit 31 and the outer edge of the exposed region 36 in the right region 361. Distance L12 is the distance between the detection unit 31 and the outer edge of the exposed region 36 in the left region 362. Distance L13 is the distance between the detection unit 31 and the outer edge of the exposed region 36 in the back region 363. Distance L14 is the distance between the detection unit 31 and the outer edge of the exposed region 36 in the front region 364. For example, each of distances L11 to L14 is the shortest distance in each of the four regions 361 to 364.

[0113] In this embodiment, the distance L11 is the longest among the four distances L11 to L14.

[0114] The groove 32, the inner recess 33, and the outer recess 34 are provided so as to surround the detection unit 31 in a plan view. The groove 32, the inner recess 33, and the outer recess 34 are discontinued in the region that includes the longest distance among the four distances L11 to L14, among the four regions 361 to 364. In this embodiment, the groove 32, the inner recess 33, and the outer recess 34 are discontinued in the right region 361 that includes the distance L11.

[0115] In this specification and claims, "surrounding the detection portion" includes not only an unbroken annular groove portion 32, inner recess portion 33, or outer recess portion 34 surrounding the detection portion 31, but also one or more interrupted groove portions 32, inner recess portions 33, or outer recess portions 34 surrounding the detection portion 31 as a whole.

[0116] During the manufacturing process of the pressure sensor 1C, the resin that has entered the interface S1 (see FIG. 7 ) is less likely to reach the detection unit 31 the longer the distance from the outer edge of the exposed region 36 to the detection unit 31. In this embodiment, in the right region 361, which includes the longest distance L11, the resin is less likely to reach the detection unit 31 compared to the other three regions 362 to 364. According to this embodiment, the groove 32, the inner recess 33, and the outer recess 34 are discontinued in the right region 361, where it is more difficult for the resin to reach the detection unit 31. This makes it possible to prevent the resin that has entered the interface S1 from reaching the detection unit 31, even if the groove 32, the inner recess 33, and the outer recess 34 are configured to be discontinued in a planar view.

[0117] The present disclosure is not limited to the above-described embodiment and can be embodied in various other forms. For example, in the above description, the coating resin 4 has a rectangular parallelepiped main body 41 and a truncated conical coating protrusion 42, but the present disclosure is not limited thereto. The shape of the coating resin 4 may be any shape that allows the detection unit 31, the groove 32, and the inner recess 33 to be exposed through the coating recess 5. For example, the coating resin 4 may be a rectangular parallelepiped having a coating recess 5 recessed downward from the top surface.

[0118] Furthermore, although the pressure sensors 1, 1A to 1C are provided with the convex portions 331, 341, and 351 in the above description, the present disclosure is not limited to this. The convex portions 331, 341, and 351 do not necessarily have to be provided.

[0119] Although the protrusion 322 is provided on the inner surface 32c of the groove in the above description, the present disclosure is not limited to this. For example, the groove 32 may have a protrusion similar to the protrusion 322 protruding from the outer surface 32b. Furthermore, the groove 32 does not necessarily have to have the protrusion 322.

[0120] Furthermore, in the third embodiment, one internal recess (second internal recess 35) is provided between the groove 32 and the first internal recess 33. However, the present disclosure is not limited to this. For example, a plurality of internal recesses connected to the groove 32 and the first internal recess 33 in the cross direction may be provided between the groove 32 and the first internal recess 33. In this case, the bottom surfaces of the plurality of internal recesses may all be located higher than the bottom surface 32a of the groove, and the bottom surfaces of the internal recesses located further inward may be located higher. In other words, the cross section of the groove 32 may be formed with a stepped shape that rises inward by the first internal recess 33 and the plurality of internal recesses located outside it. This stepped shape can provide more barriers against the highly fluid substance moving inward across the interface S1 between the film 103 and the detection element 3, thereby further preventing uncured resin from reaching the detection unit.

[0121] Furthermore, multiple outer recesses may be provided outside the groove 32. In this case, the bottom surfaces of the multiple outer recesses may all be located higher than the bottom surface 32a of the groove, and the more outer the recesses, the higher the bottom surfaces may be. In other words, the multiple outer recesses may form a stepped shape in the cross section of the groove 32 that rises outward. This stepped shape allows the flexible film 103 to penetrate deeper into the groove 32. This improves adhesion between the film 103 and the detection element 3.

[0122] In the fourth embodiment, the groove 32, the inner recess 33, and the outer recess 34 are interrupted in the region that includes the longest distance among the four distances L11 to L14 among the four regions 361 to 364. However, the present disclosure is not limited to this. For example, the groove 32, the inner recess 33, and the outer recess 34 are not limited to the region that includes the longest distance, and may be interrupted in a region having a distance L11 to L14 that makes it difficult for resin that has entered the interface S1 to reach the detection unit 31.

[0123] Any of the various embodiments or modifications described above can be combined appropriately to achieve the effects of each. In addition, combinations of embodiments, combinations of examples, or combinations of embodiments and examples are possible, and combinations of features from different embodiments or examples are also possible.

[0124] Although the present disclosure has been fully described in connection with the preferred embodiments with reference to the accompanying drawings, various changes and modifications will be apparent to those skilled in the art, and such changes and modifications are to be understood as being included within the scope of the present disclosure as defined by the appended claims unless they depart therefrom.

[0125] INDUSTRIAL APPLICABILITY The present disclosure is useful for various pressure sensors because it can prevent uncured resin from reaching a detection portion.

[0126] REFERENCE SIGNS LIST 1, 1A to 1C pressure sensor 2 substrate 2b upper surface 3 detection element 3b element upper surface 31 detection portion 32 groove portion 32b outer surface 32c inner surface 33 inner recess portion (first inner recess portion) 33a bottom surface 33b side surface 331 convex portion 332 protrusion portion 34 outer recess portion 34a bottom surface 34b side surface 342 protrusion portion 4 coating resin 5 coated recess portion

Claims

1. A pressure sensor comprising: a substrate; a detection element provided on the upper surface of the substrate for detecting pressure; and a coating resin provided on the upper surface of the substrate for covering a part of the detection element, wherein the coating resin has a coating recess that is recessed downward from the upper surface of the coating resin and exposes at least a part of the upper surface of the detection element, the detection element is provided on a part of the upper surface of the element exposed by the coating recess and serves as a detection part on which pressure acts, the detection element has a groove part that is recessed downward from the upper surface of the element and surrounds the detection part in a plan view from above, and an inner recessed part that is provided continuously between the groove part and the detection part in the plan view and is shallower and recessed downward than the groove part, the groove part has an outer surface and an inner surface that is located closer to the detection part side than the outer surface and faces the outer surface in the plan view, and the inner recessed part has a side surface that extends downward from the upper surface of the element and a bottom surface that extends from the lower edge of the side surface of the inner recessed part toward the outer surface and connects the side surface of the inner recessed part and the inner surface of the groove part.

2. The pressure sensor according to claim 1, wherein the inner recessed part has a plurality of protruding parts arranged in the vertical direction on the side surface of the inner recessed part.

3. The pressure sensor according to claim 1 or 2, wherein the height of the side surface of the inner recessed part is smaller than the length between the lower edge of the side surface of the inner recessed part at the bottom surface of the inner recessed part and the upper edge of the inner surface of the groove part.

4. The pressure sensor according to any one of claims 1 to 3, wherein the length between the lower edge of the side surface of the inner recessed part at the bottom surface of the inner recessed part and the upper edge of the inner surface of the groove part is smaller than the distance between the upper edge of the side surface of the inner recessed part and the detection part on the upper surface of the element.

5. The pressure sensor according to any one of claims 1 to 4, wherein the detection element further has an outer recessed part that is provided continuously to the outer surface of the groove part and is shallower and recessed downward than the groove part in the plan view.

6. The pressure sensor according to claim 5, wherein the outer recessed part has a side surface that extends downward from the upper surface of the element, a bottom surface that extends from the lower edge of the side surface of the outer recessed part toward the inner surface of the groove part and connects the side surface of the outer recessed part and the outer surface of the groove part, and a plurality of protruding parts arranged in the vertical direction on the side surface of the outer recessed part.

7. The inner recessed portion is provided on the bottom surface of the inner recessed portion and has a plurality of convex portions arranged in a direction from the inner side surface of the groove portion toward the side surface of the inner recessed portion in the plan view. The height of each convex portion is smaller than the depth of the inner recessed portion. The pressure sensor according to any one of claims 1 to 6.

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