JP6696494B2 - Capacitive pressure sensor - Google Patents

Description

  The present invention relates to a capacitance type pressure sensor.

  An example of an element that detects pressure is a capacitance type pressure sensor. The electrostatic capacitance type pressure sensor includes a pair of substrates having electrodes on the surfaces facing each other, the distance between the electrodes is changed by applying pressure, and the capacitance between the pair of electrodes is changed by the change between the electrodes. fluctuate. The electrostatic capacitance type pressure sensor detects pressure based on a change in electrostatic capacitance.

  In the capacitance type pressure sensor, for example, the wiring is drawn out from each of the electrodes provided on each of the pair of substrates and is connected to another device exemplified by the device for measuring the capacitance (for example, See Patent Document 1).

JP, 2009-002740, A

  In the capacitance type pressure sensor, if the wiring is drawn from each of the electrodes provided on each of the pair of substrates, the wiring structure for connecting the capacitance type pressure sensor and another device is likely to be complicated. Further, even when a plurality of layers for wiring different electrodes are provided on the same substrate, the wiring is likely to be complicated because the wiring is performed in different layers for each electrode.

  Therefore, it is an object of one aspect of the disclosed technology to provide a capacitance-type pressure sensor that can realize a simpler wiring structure.

  One aspect of the disclosed technology is exemplified by the following capacitive pressure sensor. This capacitance type pressure sensor has flexibility, and a flexible substrate having a first electrode and an extraction electrode spaced apart from the first electrode provided on one surface, and facing the one surface. A hard substrate having a second electrode on its surface, and a hollow portion supporting the space between the first electrode and the second electrode and between the first electrode and the second electrode. And an insulative wall portion that is erected so as to provide a change in capacitance that occurs when the first electrode bends with respect to the second electrode in the hollow portion. Thus, the capacitance type pressure sensor for measuring the pressure applied toward the facing surface of the first electrode and the second electrode, wherein the extraction electrode and the second electrode are It is characterized by further comprising a conductive connecting portion provided upright so as to support between the extraction electrode and the second electrode.

In such an electrostatic capacitance type pressure sensor, the flexible substrate having flexibility is formed of, for example, polyimide. The first electrode, the extraction electrode, and the second electrode may be made of a conductive material. For example, the first electrode and the extraction electrode may be formed of copper, and the second electrode may be formed of chrome. The wall portion is formed so as not to electrically connect the first electrode and the second electrode. The wall portion may be formed so as not to electrically connect the first electrode and the second electrode even if the entire wall portion is not formed of an insulator. For example, at least one of a portion contacting the first electrode and a portion contacting the second electrode of the wall portion may be formed of an insulator. In the wall portion, for example, a portion in contact with the first electrode may be formed by gold plating, and a portion in contact with the second electrode may be formed by an insulator. Since the first electrode and the second electrode are not electrically connected, the capacitance type pressure sensor can operate as a capacitor having the first electrode and the second electrode as electrode plates. By forming the wall portion so as to provide the hollow portion between the first substrate and the second substrate, the flexible substrate to which pressure is applied can be bent toward the hard substrate. Further, in the capacitance type pressure sensor, the extraction electrode and the second electrode are supported by the conductive connecting portion. The extraction electrode and the second electrode are electrically connected by being connected by the conductive connecting portion. By electrically connecting the extraction electrode and the second electrode, it is possible to draw out the wiring from the second electrode from the extraction electrode. Therefore, the wiring from the first electrode and the wiring from the second electrode can be drawn from the same layer on the flexible substrate. Therefore, according to this capacitance type pressure sensor, a simpler wiring structure can be realized. Further, it becomes possible to simplify the layer structure for forming the electrodes.

  Further, the disclosed technology may have the following features. The connection portion is formed in a ring shape in a plan view. Since the second electrode is supported by the ring-shaped connecting portion, when the pressure is applied to the flexible substrate and the flexible substrate bends toward the rigid substrate, the strain generated in the flexible substrate is suppressed. It The ring shape is not limited to the circular shape, and may be any shape as long as the wall portion does not break in the middle. Examples of the ring shape include a substantially circular shape, a substantially elliptical shape, a substantially triangular shape, a substantially quadrangular shape, a substantially pentagonal shape, a substantially hexagonal shape, and a substantially octagonal shape.

  Further, the disclosed technology may have the following features. The wall portion is formed in an annular shape in a plan view, and the area of the region surrounded by the connection portion is smaller than the area of the region surrounded by the wall portion in the plan view. By having such a feature, the size of the electrostatic capacity type pressure sensor provided with the connection part can be suppressed. That is, it is possible to reduce the size of the capacitance type pressure sensor including the connecting portion.

  Further, the disclosed technology may have the following features. The hard substrate is formed of a member having rigidity. The member having rigidity is, for example, glass. By having such a characteristic, even if pressure is applied to the electrostatic capacitance type pressure sensor, the variation of the area serving as a reference for pressure calculation is suppressed. Therefore, by having such a characteristic, the electrostatic capacitance type pressure sensor can detect the pressure with higher accuracy than the pressure sensor formed of the member whose hard substrate is easily deformed.

  Further, the disclosed technology may have the following features. The flexible substrate includes a plurality of the first electrodes, and a plurality of the hard substrates corresponding to the plurality of first electrodes. Further, the disclosed technology may have the following features. The first electrodes are arranged in a grid pattern on the flexible substrate at a predetermined interval. In the capacitance type pressure sensor having such characteristics, the plurality of first electrodes are separated from each other and the plurality of hard substrates are separated from each other. Therefore, when pressure is applied to the electrostatic capacitance type pressure sensor, one of the plurality of flexible substrates that are separated and contacted does not hinder the bending of the other of the plurality of adjacent flexible substrates. Therefore, the bending of the flexible substrate when pressure is applied to the capacitance type pressure sensor is not hindered, and the pressure applied to the capacitance type pressure sensor can be measured with high accuracy.

  The capacitance type pressure sensor can realize a simpler wiring structure.

FIG. 1 is a first diagram showing a schematic configuration of a pressure sensor according to an embodiment. FIG. 2 is a second diagram showing a schematic configuration of the pressure sensor according to the embodiment. FIG. 3 is a first diagram illustrating an example of the pressure sensor according to the embodiment. FIG. 4 is a second diagram illustrating an example of the pressure sensor according to the embodiment. FIG. 5 is a diagram showing an example of the configuration of the capacitance measuring circuit. FIG. 6 is a diagram showing an example of a state before pressure is applied to the pressure sensor. FIG. 7: is a figure which shows an example of the state when pressure is applied to a pressure sensor. FIG. 8A is a first diagram illustrating an example of a manufacturing process of the pressure sensor according to the embodiment. FIG. 8B is a second diagram illustrating an example of the manufacturing process of the pressure sensor according to the embodiment. FIG. 8C is a third diagram illustrating an example of the manufacturing process of the pressure sensor according to the embodiment. FIG. 8D is a fourth diagram illustrating an example of the manufacturing process of the pressure sensor according to the embodiment. FIG. 8E is a fifth diagram illustrating an example of the manufacturing process of the pressure sensor according to the embodiment. FIG. 8F is a sixth diagram showing an example of the manufacturing process of the pressure sensor according to the embodiment. FIG. 8G is a seventh diagram illustrating an example of the manufacturing process of the pressure sensor according to the embodiment. FIG. 8H is an eighth diagram showing an example of the manufacturing process of the pressure sensor according to the embodiment. FIG. 8I is a ninth diagram showing an example of the manufacturing process of the pressure sensor according to the embodiment. FIG. 9: is a figure which shows an example of the cross section of the pressure sensor which concerns on a modification.

  Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.

<Application example>
1 and 2 are diagrams showing a schematic configuration of a pressure sensor 100 according to an application example. FIG. 1 is an example of a schematic view of the pressure sensor 100 in a plan view, and FIG. 2 is an example of a cross-sectional view taken along the line BB of FIG. In FIG. 1, the fixed substrate side plated portion 24, the first hollow portion 18, the fixed electrode 22, and the substrate portion 21 which are invisible in a plan view are shown by dotted lines. As can be understood with reference to FIGS. 1 and 2, the pressure sensor 100 includes a movable portion 10 and a fixed substrate portion 20. The movable portion 10 has flexibility, and a first movable electrode 121 and a second movable electrode 122 separated from the first movable electrode 121 are provided on one surface of the movable portion 10. The fixed electrode 22 is provided on the surface of the fixed substrate portion 20 facing the one surface. When pressure is applied to the movable portion 10, the movable portion 10 bends toward the fixed substrate portion 20 side, and the distance between the first movable electrode 121 and the fixed electrode 22 changes. The pressure sensor 100 is a capacitance-type pressure sensor that detects pressure based on variation in capacitance with variation in the distance between the first movable electrode 121 and the fixed electrode 22.

In the fixed substrate portion 20, the substrate portion 21 on which the fixed electrode 22 is provided is formed by a member having rigidity. The member having rigidity is, for example, glass. The pressure is calculated as a force applied per unit area, but the rigidity of the substrate portion 21 suppresses the fluctuation of the area serving as a reference for pressure calculation, and the pressure detection accuracy of the pressure sensor 100 is increased. The first movable electrode 121, the second movable electrode 122, and the fixed electrode 22 may be formed of conductive members. For example, the first movable electrode 121 and the second movable electrode 122 are made of copper, and the fixed electrode 22 is made of chromium. The surface of the first movable electrode 121 and the second movable electrode 122 on the side facing the fixed electrode 22 is plated to protect the first movable electrode 121. The plating process is, for example, a gold plating process. The fixed substrate portion 20 is further provided with an insulating portion 23 that surrounds the periphery of the fixed electrode 22 and covers a portion above the fixed electrode 22. The insulating part 23 may be formed of an insulator, and the insulator is, for example, tetraethoxysilane (TEOS) or silicon dioxide. The insulating portion 23 is provided with a space 23b in a part of a region where the first movable electrode 121 and the fixed electrode 22 overlap each other in a plan view, and a plan view is obtained from a region near an edge of the space 23b toward the movable unit 10 side. At, the third plated portion 241 is formed so as to surround the space 23b. The inner side surface 23a of the space 23b and the third plated portion 241 become a wall portion of the first hollow portion 18. As shown in FIG. 2, the insulating portion 23 is interposed between the third plated portion 241 and the fixed electrode 22, and the third plated portion 241 and the fixed electrode 22 do not come into contact with each other. Therefore, the first movable electrode 121 and the fixed electrode 22 are not electrically connected by the wall portion of the first hollow portion 18. The first hollow portion 18 enables the movable portion 10 to bend toward the fixed substrate portion 20 when pressure is applied to the movable portion 10. The pressure sensor 100 further includes a fourth plated portion 242, which electrically connects the second movable electrode 122 and the fixed electrode 22, between the second movable electrode 122 and the fixed electrode 22. The shape of the fourth plated portion 242 is not limited, but when the shape of the fourth plated portion 242 in plan view is formed in a ring shape as illustrated in FIGS. 3 and 4, pressure is applied to the movable portion 10. Is applied and the movable portion 10 bends toward the fixed substrate portion 20, the strain generated in the movable portion 10 is suppressed. When the fourth plated portion 242 is formed in a ring shape in plan view, the area of the region surrounded by the fourth plated portion 242 in plan view is smaller than the area of the first hollow portion 18 in plan view. To be done. The movable portion 10 is an example of a “flexible substrate”. The first movable electrode 121 is an example of a “first electrode”. The second movable electrode 122 is an example of a “takeout electrode”. The fixed electrode 22 is an example of the “second electrode”. The fixed substrate unit 20 is an example of a “hard substrate”. The inner side surface 23a of the space 23b and the third plated portion 241 are examples of a "wall portion". The fourth plating part 242 is an example of a “connecting part”.

  As described above, the fourth plated portion 242 may be formed in a ring shape in plan view. In the pressure sensor 100, the fourth plating portion 242 is formed in a ring shape in a plan view, so that the bending of the movable portion 10 that occurs when the movable portion 10 is pressed is generated more uniformly in the entire movable portion 10. become. That is, in the pressure sensor 100 provided with the fourth plated portion 242 formed in a ring shape in a plan view, the first movable electrode 121 is parallel to the fixed electrode 22 when pressure is applied to the movable portion 10. While maintaining such a state, the movable portion 10 can bend toward the fixed substrate portion 20. Therefore, the pressure sensor 100 can detect the pressure with higher accuracy than a pressure sensor in which the fourth plating portion 242 is not formed in a ring shape in plan view.

  When the fourth plated portion 242 is formed in a ring shape, in the pressure sensor 100, the space between the movable portion 10 and the fixed substrate portion 20 is supported by the third plated portion 241 which is the wall portion of the first hollow portion 18. In addition, it is also supported by the fourth plated portion 242. Therefore, the durability of the pressure sensor 100 is improved.

  In the pressure sensor 100, the board portion 21 is formed of a member having rigidity. Therefore, even if a pressure is applied to the pressure sensor 100, the variation of the area serving as a reference for pressure calculation is suppressed. Therefore, the pressure sensor 100 can detect the pressure with higher accuracy than the pressure sensor formed by the member whose substrate portion 21 is easily deformed.

<Embodiment>
3 and 4 are diagrams showing an example of the pressure sensor according to the embodiment. 3 and 4 are diagrams showing the configuration of the pressure sensor 100 described in FIGS. 1 and 2 in more detail. FIG. 3 is an example of a plan view of the pressure sensor 100, and FIG. 4 is an example of a cross-sectional view taken along the line AA of FIG. In FIG. 3, the fixed substrate side plated portion 24, the first hollow portion 18, the second hollow portion 19, the fixed electrode 22, and the substrate portion 21 which are invisible in a plan view are shown by dotted lines. In FIG. 3, three pressure sensors 100 (100a, 100b, 100c) are illustrated, and the connector 200 and the capacitance measuring circuit 300 are also illustrated. The three pressure sensors 100a, 100b, 100c share the sheet substrate 11. As can be understood with reference to FIG. 4, in the embodiment, the movable portion 10 has the movable electrode 12 including the second movable electrode 122 in addition to the first movable electrode 121. Hereinafter, in this specification, the direction from the second hollow portion 19 to the first hollow portion 18 in FIG. 3 is right, and the opposite direction is left. Further, in FIG. 3, the direction from the pressure sensor 100a to the pressure sensor 100c is the rear, and the opposite direction is the front. Further, the direction from the movable part 10 to the fixed substrate part 20 in FIG. 4 is downward and the opposite direction is upward.

  The movable portion 10 includes a sheet substrate 11, a movable electrode 12, and a movable portion-side plated portion 14. The sheet substrate 11 is formed of a flexible member (for example, polyimide). The thickness of the sheet substrate 11 is, for example, 25 μm. Here, the thickness of the sheet substrate 11 is the vertical length of the sheet substrate 11. A movable electrode 12 formed of a conductive member (eg, copper) is provided on the lower surface of the sheet substrate 11. The movable electrode 12 includes the first movable electrode 121 and the second movable electrode 122 provided apart from the first movable electrode 121 as described above. The thickness of the movable electrode 12 is, for example, 10 μm. The length of the first movable electrode 121 in the left-right direction is, for example, 2.0 mm. The length of the second movable electrode 122 in the left-right direction is, for example, 0.5 mm. The length in the front-rear direction of the first movable electrode 121 and the second movable electrode 122 is, for example, 1 mm to 2 mm. The distance between the first movable electrode 121 and the second movable electrode 122 is, for example, 0.1 mm. A movable portion side plated portion 14 is provided on the lower surface of the movable electrode 12. The movable part side plating part 14 includes a first plating part 141 provided on the lower surface of the first movable electrode 121 and a second plating part 142 provided on the lower surface of the second movable electrode 122. The movable part side plating part 14 is formed by, for example, gold plating.

The fixed substrate portion 20 includes a substrate portion 21, a fixed electrode 22, an insulating portion 23, and a fixed substrate side plated portion 24. The substrate portion 21 is formed of a member (for example, glass) that does not easily deform. The thickness of the substrate portion 21 is, for example, 300 μm to 600 μm. Since the base plate portion 21 is formed of a member that is not easily deformed, the fixed base plate portion 20 is suppressed from being deformed even when the movable portion 10 is bent by applying pressure to the sheet base plate 11. A fixed electrode 22 formed of a conductive member (eg, chrome) is arranged on the upper surface of the substrate portion 21. Further, an insulating portion 23 that surrounds the periphery of the fixed electrode 22 and covers a portion above the fixed electrode 22 is provided. The insulating portion 23 is formed of an insulating material (for example, tetraethoxysilane (TEOS) or silicon dioxide). The insulating portion 23 has a thickness of 0.5 μm, for example. The insulating portion 23 is provided with the above-described first hollow portion 18 in a part of a region where the first movable electrode 121 and the fixed electrode 22 overlap each other in a plan view, and the second movable electrode 122 and the fixed electrode 22 in a plan view. The above-mentioned second hollow portion 19 is provided in a part of the region where and overlap. The first hollow portion 18 and the second hollow portion 19 are formed as through holes that extend from the surface of the insulating portion 23 on the movable portion 10 side to the surface on the fixed electrode 22 side. The diameter of the first hollow portion 18 in a plan view is, for example, 0.6 mm to 1.2 mm. When the pressure sensor 100 is viewed in a plan view, the area of the second hollow portion 19 is smaller than the area of the first hollow portion 18. That is, the diameter of the second hollow portion 19 when seen in a plan view is smaller than the diameter of the first hollow portion 18 when seen in a plan view. The distance d between the fixed electrode 22 and the first movable electrode 121 of the first hollow portion 18 when no pressure is applied is, for example, 1 μm. In addition to a part of the upper surface of the insulating portion 23, the fixed substrate side plated portion 24 is provided on the inner side surface and the bottom portion of the second hollow portion 19. The fixed substrate side plating section 24 includes a third plating section 241 and a fourth plating section 242. The third plated portion 241 is provided in a region near the edge of the first hollow portion 18 on the upper surface of the insulating portion 23. The fourth plated portion 242 is provided on the upper surface of the insulating portion 23 in the region near the edge of the second hollow portion 19, the inner side surface of the second hollow portion 19, and the bottom portion. The fourth plated portion 242 reaches the fixed electrode 22 via the second hollow portion 19, and is formed so as to project from above the second hollow portion 19 toward the second movable electrode 122. In the embodiment, the fourth plated portion 242 is formed in a ring shape in plan view. The fixed substrate side plated portion 24 is formed by, for example, gold plating. By joining the movable portion side plated portion 14 and the fixed substrate side plated portion 24, the movable portion 10 and the fixed substrate portion 20 are integrated, and the pressure sensor 100 is formed. Further, the second movable electrode 122 and the fixed electrode 22 are electrically connected by joining the second plated portion 142 and the fourth plated portion 242.

  The second movable electrode 122 and the connector 200 are connected by the signal line 15 extending from the second movable electrode 122. Further, the first movable electrode 121 of the pressure sensors 100a and 100b and the first movable electrode 121 of the pressure sensors 100b and 100c are connected by a ground (GND) line 16a extending from the first movable electrode 121. In FIG. 3, the distance between the adjacent pressure sensors 100 is, for example, 0.1 mm to 0.3 mm. That is, the length of the GND wire 16a is 0.1 mm to 0.3 mm. Further, the first movable electrode 121 of the pressure sensor 100c is connected to the connector 200 by the GND line 16b extending from the first movable electrode 121. That is, the pressure sensors 100a, 100b, 100c share GND. As can be understood with reference to FIGS. 3 and 4, in the pressure sensor 100, both the signal line 15 and the GND line 16 are formed on the lower surface of the sheet substrate 11. That is, in the pressure sensor 100, the wiring extending from the first movable electrode 121 and the wiring extending from the fixed electrode 22 are formed in the same layer. By adopting such a configuration, the pressure sensor 100 realizes a simple wiring structure.

  In the pressure sensor 100 having the above-described configuration, the area where the first movable electrode 121 overlaps with the fixed electrode 22 and the area where the fixed electrode 22 overlaps with the first movable electrode 121 are disposed as electrodes. It works as a plate capacitor. The capacitance C of the capacitor is calculated by the following (Equation 1) using, for example, the distance d and the area S (see FIG. 2) of the region where the first movable electrode 121 and the fixed electrode 22 overlap. .

In the above (Formula 1), ε ₀ is the dielectric constant of vacuum, and ε _r is the relative dielectric constant of the atmosphere. That is, according to (Equation 1), the electrostatic capacitance C changes in accordance with the change in the distance d between the first movable electrode 121 and the fixed electrode 22 caused by the force applied to the movable portion 10. I understand.

  Further, the pressure P is calculated by the following (Formula 2) using the area S described above, for example.

  In the above (Formula 2), F is the magnitude of the force applied to the pressure sensor 100. As described above, since the substrate portion 21 is formed of a member that is not easily deformed, even if pressure is applied to the pressure sensor 100, fluctuations in the area S that serves as a reference for pressure calculation are suppressed. Therefore, the pressure sensor 100 can detect the pressure with higher accuracy than the pressure sensor formed by the member whose substrate portion 21 is easily deformed.

FIG. 5 is a diagram showing an example of the configuration of the capacitance measuring circuit 300. In FIG. 5, the pressure sensors 100a, 100b, 100c are also illustrated. Further, in FIG. 5, the illustration of the connector 200 is omitted. The capacitance measuring circuit 300 includes two multiplexers 301 and 301 (denoted as MUX in the figure) and a converter 302. A signal associated with a change in electrostatic capacitance of the pressure sensors 100a, 100b, 100c is input to each of the multiplexers 301, 301 via a signal line 15. Each of the multiplexers 301, 301 outputs a selected one of the signals input from the pressure sensors 100a, 100b, 100c. In FIG. 5, the illustration of the selection signals used for selecting the signals output from the multiplexers 301 and 301 is omitted. The converter 302 inputs the signals output from the multiplexers 301, 301 to the converter 302. The converter 302 stores, for example, a correspondence relationship between signal values input from the multiplexers 301 and 301 and pressure. The correspondence relationship managed by the converter 302 may be, for example, a table indicating the correspondence between the input signal value and the pressure, or a mathematical expression for calculating the pressure from the input signal value. The converter 302 converts the signal value input from the multiplexers 301 and 301 into a signal value indicating pressure and outputs a signal value indicating pressure, for example, according to the correspondence relationship.

  As illustrated in FIG. 3, it is possible to arrange the plurality of pressure sensors 100 by sharing the sheet substrate 11. That is, by providing the plurality of movable electrodes 12 on the single sheet substrate 11, the plurality of movable electrodes 12 and the plurality of fixed substrate portions 20 are arranged on the single sheet substrate 11 in a row, a grid or an array. It is possible. In this case, the plurality of movable electrodes 12 are separated from each other and the plurality of fixed substrate portions 20 are separated from each other. Therefore, when a pressure is applied to the pressure sensor 100, one of the plurality of movable portions 10 that is in contact with or separated from the other does not hinder the bending of the other of the plurality of adjacent movable portions 10. Therefore, the bending of the movable portion 10 when pressure is applied to the pressure sensor 100 is not hindered, and the pressure applied to the pressure sensor 100 can be measured with high accuracy.

  FIG. 6 shows an example of a state before pressure is applied to the pressure sensor 100, and FIG. 7 shows an example of a state when pressure is applied to the pressure sensor 100. In the pressure sensor 100, when pressure is applied from above the first hollow portion 18, the movable portion 10 including the sheet substrate 11 and the first movable electrode 121 responds to the applied force as illustrated in FIG. 7. And bends toward the fixed substrate portion 20. When the pressure is no longer applied to the pressure sensor 100, the pressure sensor 100 returns from the state of FIG. 7 to the state of FIG. That is, in the pressure sensor 100, the distance d between the first movable electrode 121 and the fixed electrode 22 changes according to the applied force. When the distance d changes, the capacitance of the pressure sensor 100 changes according to (Equation 1). For example, the pressure applied to the pressure sensor 100 is detected by measuring the variation in the capacitance of the pressure sensor 100 by the capacitance measuring circuit 300 illustrated in FIG.

By the way, the pressure sensor 100 has a second hollow portion 19 in addition to the first hollow portion 18. On the inner side surface of the second hollow portion 19, as described above, the fourth plated portion 242 which is formed in a cylindrical shape in a plan view and reaches the second movable electrode 122 from the fixed electrode 22 is formed. If only the fixed electrode 22 and the second movable electrode 122 are electrically connected, it is sufficient to connect the fourth plated portion 242 with a single wire without forming the fourth plated portion 242 into a cylindrical shape in plan view. However, in the pressure sensor 100 according to the embodiment, both the first movable electrode 121 and the second movable electrode 122 that are provided separately are provided on the sheet substrate 11. Therefore, when a force is applied from above the first movable electrode 121, the first movable electrode 121 bends toward the fixed electrode 22 side, and the second movable electrode 122 also distorts toward the fixed electrode 22 side. In order to detect the pressure with high accuracy, it is preferable that the first movable electrode 121 bends relative to the fixed electrode 22 in the front-rear direction and the left-right direction. However, when the second movable electrode 122 is distorted to the fixed electrode 22 side, the first movable electrode 121 is affected by the distortion, and it is difficult to bend the first movable electrode 121 without being biased with respect to the fixed electrode 22. Therefore, in the pressure sensor 100 according to the embodiment, the cross-sectional shape of the fourth plated portion 242 when seen in a plan view is formed in a ring shape. As a result, the second movable electrode 12 when pressure is applied is compared with the configuration in which the fixed electrode 22 and the second movable electrode 122 are connected by one wire.
The distortion in the two parts is suppressed. As a result, when the first movable electrode 121 bends with respect to the fixed electrode 22, a deviation in the front-rear direction and the left-right direction is suppressed. Further, the fourth plated portion 242 having a ring-shaped cross section can stably support the second movable electrode 122, as compared with the case where the single movable wire supports the second movable electrode 122.

<Manufacturing process of the pressure sensor 100>
8A to 8I are views showing an example of a manufacturing process of the pressure sensor 100. Hereinafter, an example of a manufacturing process of the pressure sensor 100 will be described with reference to FIGS. 8A to 8I.

(Manufacturing process of the fixed substrate part 20)
8A to 8E show an example of a manufacturing process of the fixed substrate section 20. In FIG. 8A, the fixed electrode 22 is formed on the surface of the substrate portion 21 facing the movable portion 10. Subsequently, in FIG. 8B, an insulating film 231 is formed so as to cover the fixed electrode 22. Further, in FIG. 8B, a resist film 51 is formed on the surface of the insulating film 231 facing the movable portion 10. In FIG. 8C, the resist film 51 having a predetermined pattern is formed on the insulating film 231 by performing photoresist using a photomask having a desired pattern formed on the resist film 51. In FIG. 8D, the insulating part 23 is formed by performing the etching process and further removing the resist film 51. In FIG. 8E, the fixed substrate side plated portion 24 is formed on the surface of the insulating portion 23 facing the movable portion 10. In the process illustrated in FIG. 8E, the fixed substrate side plated portion 24 is formed in a desired region by performing plating treatment after plating resist is applied to a region where the fixed substrate side plated portion 24 is not formed.

(Manufacturing process of the movable part 10)
8F and 8G show an example of a manufacturing process of the movable part 10. In FIG. 8F, the movable electrode 12 is formed on the surface of the flexible sheet substrate 11 that faces the fixed substrate portion 20. Further, the surface of the movable electrode 12 facing the fixed substrate portion 20 is plated, so that the movable portion side plated portion 14 is formed. In FIG. 8G, the etching resist is applied to the regions corresponding to the first movable electrode 121 and the second movable electrode 122 on the surface of the movable portion side plated portion 14 facing the fixed substrate portion 20, and then the etching is performed. As a result, the first movable electrode 121 and the second movable electrode 122 are formed. The fixed substrate side plated portion 24 may be formed by sputtering. That is, the pattern of the fixed substrate side plated portion 24 is formed by forming a plated layer on the surface of the insulating portion 23 facing the movable portion 10 with a sputtering device, and then applying a resist and etching. May be.

(Step of joining the movable portion 10 and the fixed substrate portion 20)
8H and 8I show an example of a process of joining the fixed substrate unit 20 and the movable unit 10. In FIG. 8H, the movable portion 10 and the fixed substrate portion 20 are joined together. The joining method is not particularly limited. The movable portion 10 and the fixed substrate portion 20 may be joined by room temperature joining, for example. In the room temperature bonding, for example, with respect to the surface of the movable portion side plating portion 14 of the movable portion 10 facing the fixed substrate portion 20 and the surface of the fixed substrate side plating portion 24 of the fixed substrate portion 20 facing the movable portion 10, A treatment for smoothing the surface and a treatment for removing impurities from the surface to clean the surface are performed. When the movable portion side plated portion 14 and the fixed substrate side plated portion 24 that have been subjected to these treatments come into contact with each other, the movable portion is caused by the intermolecular force acting between the movable portion side plated portion 14 and the fixed substrate side plated portion 24. 10 and the fixed substrate portion 20 are joined together. FIG. 8I exemplifies a state in which three pressure sensors 100 manufactured by the steps of FIGS. 8A to 8H are arranged so as to share the sheet substrate 11. As illustrated in FIG. 6I, in the pressure sensor 100, the sheet substrate 11 is shared and a plurality of pressure sensors 100 are arranged side by side, whereby the area for pressure detection can be expanded.

In addition, in the process of joining the movable portion 10 and the fixed substrate portion 20, the movable portion 10 and the fixed substrate portion 20 are manufactured without performing the process of flattening the surfaces of the movable portion side plated portion 14 and the fixed substrate side plated portion 24. In the step, the flatness of the surface may be ensured. For example, in the manufacturing process of the movable part 10, a metal (for example, copper) that will be the movable electrode 12 is flattened by CMP (Chemical Mechanical Polishing) on the sheet substrate 11, and is then flattened on the movable part by a sputtering device. The film 14 may be formed.

<Modification>
In the embodiment, the space between the second movable electrode 122 and the fixed electrode 22 is supported by the fourth plated portion 242 formed as the wall portion of the second hollow portion 19. However, joining between the second movable electrode 122 and the fixed electrode 22 is not limited to the fourth plated portion 242 formed as the wall portion of the second hollow portion 19. FIG. 9: is a figure which shows an example of the cross section of the pressure sensor 100a which concerns on a 1st modification. The pressure sensor 100a is different from the pressure sensor 100 in that the insulating portion 23 is provided with a pillar portion 23c instead of the second hollow portion 19. The column portion 23c is provided between the second movable electrode 122 and the fixed electrode 22 in a substantially columnar shape. A fourth plated portion 242a is provided on the side surface of the pillar portion 23c. In the case of the first modification, the fourth plated portion 242a supports between the second movable electrode 122 and the fixed electrode 22. Such fourth plating portion 242a also suppresses distortion in the second movable electrode 122 when pressure is applied to the first movable electrode 121. Further, the second movable electrode 122 and the fixed electrode 22 can also be electrically connected by the fourth plated portion 242a. In the modification, the pillar portion 23c has a substantially columnar shape, but the shape is not limited to the substantially columnar shape, and it may be a substantially elliptical column shape, a substantially triangular column shape, a substantially square column shape, a substantially pentagonal column shape, or a substantially hexagonal column shape. The shape may be a substantially octagonal prism shape.

  The embodiments and modifications disclosed above can be combined with each other.

100, 100a, 100b, 100c ... Pressure sensor 10 ... Movable part 11 ... Sheet substrate 12 ... Movable electrode 121 ... First movable electrode 122 ... Second movable electrode 14 ... Movable part side plating part 141 ... 1st plating part 142 ... 2nd plating part 15 ... Signal line 16, 16a, 16b ... GND line 18 ... 1st hollow part 19 ... 2 Hollow portion 20 ... Fixed substrate portion 21 ... Substrate portion 22 ... Fixed electrode 23 ... Insulating portion 23a ... Inner side surface 24 ... Fixed substrate side plated portion 241 ... Third plating Part 242 ... Fourth plated part 51 ... Resist film 200 ... Connector 231 ... Insulating film 300 ... Capacitance measuring circuit 301 ... Multiplexer 302 ... Converter

Claims (6)

A flexible substrate having flexibility and provided on one surface with a first electrode and an extraction electrode separated from the first electrode;
A hard substrate having a second electrode on a surface facing the one surface;
An insulative wall portion that stands between the first electrode and the second electrode and that is erected so as to provide a hollow portion between the first electrode and the second electrode; The first electrode and the second electrode by detecting a change in capacitance caused by bending of the first electrode with respect to the second electrode in the hollow portion. A capacitive pressure sensor for measuring the pressure applied to the facing surface of
Between the extraction electrode and the second electrode, a conductive connecting portion is provided upright so as to support between the extraction electrode and the second electrode.
Capacitive pressure sensor. The connection portion is formed in a ring shape in a plan view,
The capacitance type pressure sensor according to claim 1. The wall portion is formed in a ring shape in a plan view,
In a plan view, the area of the region surrounded by the connecting portion is smaller than the area of the region surrounded by the wall portion,
The capacitance type pressure sensor according to claim 2. The hard substrate is formed of a member having rigidity,
The electrostatic capacitance type pressure sensor according to any one of claims 1 to 3. The flexible substrate includes a plurality of the first electrodes, and has a plurality of the hard substrates corresponding to the plurality of first electrodes,
The electrostatic capacitance type pressure sensor according to any one of claims 1 to 4. The first electrodes are arranged in a grid pattern on the flexible substrate at predetermined intervals.
The electrostatic capacitance type pressure sensor according to claim 5.