Sensor

Abstract

To provide a sensor capable of detecting moisture without consuming power.SOLUTION: A pair of detection electrodes 5, 6 made of metals having different ionization tendencies and first and second deliquescent substances 11, 12 that absorb moisture and become first and second electrolyte solutions are installed inside a detection object space, the first deliquescent substance 11 is disposed so as to cover one detection electrode 5 that becomes a positive electrode, the first electrolyte solution contains a metal ion depositable to the side of one detection electrode 5, the second deliquescent substance 12 is disposed so as to cover the other detection electrode 6 that becomes a negative electrode, and the first deliquescent substance 11, and a separator 4c for suppressing mixture of the first and second electrolyte solutions protrudes between the pair of detection electrodes 5, 6.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a sensor, and more particularly to a sensor suitable for detecting moisture that has infiltrated into the internal space of a hermetically sealed package, for example. [Background technology]

[0002] Sensors that detect moisture, such as humidity sensors, include those that place a moisture-sensitive film between two electrodes and detect humidity based on changes in capacitance or impedance between the two electrodes due to humidity (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-94663 Summary of the Invention [Problem to be solved by the invention]

[0004] As described above, in a sensor that detects changes in capacitance or impedance between two electrodes, a current must be constantly flowing between the two electrodes, posing the problem of power consumption.

[0005] The present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide a sensor that can detect moisture without consuming power. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention is configured as follows.

[0007] (1) A sensor according to the present invention is a sensor for detecting moisture in a space to be detected, the sensor including: an insulating base; a pair of detection electrodes made of metals with different ionization tendencies formed on an upper surface of the base; a first deliquescent substance that absorbs moisture to become a first electrolyte solution; and a second deliquescent substance that absorbs moisture to become a second electrolyte solution, the first deliquescent substance being disposed so as to cover one of the pair of detection electrodes that is a positive electrode; the first electrolyte solution contains ions of a metal that can be precipitated on the one detection electrode side; the second deliquescent substance being disposed so as to cover the other of the pair of detection electrodes that is a negative electrode and the first deliquescent substance; the pair of detection electrodes are formed on an upper surface of the base with a gap therebetween; and a separator that suppresses mixing of the first electrolyte solution and the second electrolyte solution is protruded from the spaced-apart area on the upper surface of the base; and the sensor detects intrusion of moisture into the space to be detected based on an electromotive force generated between the pair of detection electrodes.

[0008] According to the sensor of the present invention, when air containing moisture enters the detection target space, the first and second deliquescent substances absorb moisture to become the first and second electrolyte solutions, and the metal of the other detection electrode, which has a greater tendency to ionize, dissolves into the second electrolyte solution to become metal ions and emits electrons, causing the other detection electrode to become a negative electrode. The electrons emitted from the negative electrode flow into one detection electrode, which becomes a positive electrode, generating an electromotive force between the pair of detection electrodes. In other words, when air containing moisture enters the detection target space, a chemical battery is formed and an electromotive force is generated between the pair of detection electrodes, and the intrusion of air containing moisture can be detected based on this electromotive force.

[0009] In this way, with the sensor of the present invention, there is no need to keep a current flowing between the two electrodes, as in conventional sensors that detect changes in capacitance or impedance between the two electrodes, so no power is consumed, thereby achieving so-called energy conservation.

[0010] Furthermore, since a chemical battery having a simple structure is constructed to detect moisture, the structure of the sensor can be simplified and it is easy to reduce the size of the sensor.

[0011] Furthermore, in one of the detection electrodes, which serves as the positive electrode, the electrons that flow in combine with the ions of a metal in the first electrolyte solution that has a low ionization tendency, causing the metal to precipitate, so hydrogen is not generated at the positive electrode, as in a Voltaic cell. This makes it possible to prevent polarization, in which the generated hydrogen covers the positive electrode, inhibiting the subsequent reaction and causing a sudden drop in electromotive force, as in a Voltaic cell.

[0012] In addition, a separator that suppresses mixing of the first and second electrolyte solutions is protruded between a pair of detection electrodes formed at a distance from each other on the upper surface of the base, so that a decrease in electromotive force due to mixing of the first and second electrolyte solutions can be suppressed. Meanwhile, the second deliquescent material is arranged so as to cover the other detection electrode and the first deliquescent material, so that mixing of the first and second electrolyte solutions is not completely prevented, but rather the first and second electrolyte solutions are gradually mixed, thereby adjusting the imbalance of charges that occurs between one detection electrode side and the other detection electrode side, and suppressing a decrease in electromotive force.

[0013] (2) In a preferred embodiment of the present invention, the space to be detected is an internal space of a package hermetically sealed with an inert gas or dry air.

[0014] According to this embodiment, the internal space of a package that is hermetically sealed with an inert gas or dry air is the detection target space. Therefore, for example, the internal space of a package of an electronic device that houses various elements that may deteriorate and have their characteristics deteriorated due to the infiltration of moisture is the detection target space, and the airtight state of the space can be monitored with a simple configuration.

[0015] (3) In another embodiment of the present invention, a portion of the second deliquescent material extends beyond the separator and covers the first deliquescent material.

[0016] According to this embodiment, a portion of the second deliquescent material extends beyond the separator and covers the first deliquescent material, so that the mixing of the first and second electrolyte solutions produced when the first and second deliquescent materials absorb moisture is not completely prevented. As the mixing progresses gradually, the charge imbalance occurring between one detection electrode side and the other detection electrode side can be adjusted, thereby suppressing a decrease in electromotive force.

[0017] (4) In still another embodiment of the present invention, the upper surface of the substrate has a recess in the center that is recessed downward compared to the outer periphery, and the separator is protruded into the recess, and the first deliquescent material and the second deliquescent material are arranged therein.

[0018] According to this embodiment, the first and second deliquescent substances are arranged in a recess recessed downward in the center of the base, separated by a separator, so that the first and second electrolyte solutions produced when the first and second deliquescent substances absorb moisture can be stably held in each recess separated by the separator.

[0019] (5) In one embodiment of the present invention, the separator is integrally formed with the substrate from the same material.

[0020] According to this embodiment, the separator is formed integrally with the substrate from the same material, and therefore can be formed with higher precision by etching or the like, compared to forming the separator from a material separate from the substrate.

[0021] (6) In another embodiment of the present invention, the base is made of an anisotropic etching material, and the surface of the separator facing the other of the pair of detection electrodes is an inclined surface that slopes downward toward the other detection electrode.

[0022] According to this embodiment, the surface of the separator facing the other detection electrode is an inclined surface that slopes downward toward the other detection electrode, so that cations in the second electrolyte solution generated when the second deliquescent material absorbs moisture can easily move along the inclined surface toward one detection electrode. Metal ions (cations) in the first electrolyte solution generated when the first deliquescent material on one detection electrode absorbs moisture are less likely to move across the separator to the other detection electrode on the opposite side because the side of the separator facing the one detection electrode is not an inclined surface.

[0023] This promotes the migration of cations in the second electrolyte solution, which is generated when the second deliquescent material absorbs water, to the opposite side, that is, the one detection electrode, contributing to the generation of a stable electromotive force. Also, the deposition of metal ions in the first electrolyte solution, which is generated when the first deliquescent material absorbs water, on the other detection electrode side can be suppressed, thereby suppressing a decrease in the electromotive force. Effect of the Invention

[0024] According to the present invention, when air containing moisture infiltrates the space to be detected, a chemical battery is formed and an electromotive force is generated, and the infiltration of air containing moisture into the space to be detected can be detected based on this electromotive force.

[0025] In this way, the sensor of the present invention detects moisture by configuring a chemical battery with a simple configuration, so that no power is consumed, thereby saving energy, and the sensor configuration can be simplified to achieve miniaturization.

[0026] In addition, at one of the detection electrodes, which serves as the positive electrode, the metal ions contained in the first electrolyte solution are precipitated as metal, and hydrogen is not generated at the positive electrode as in a Voltaic cell. This prevents polarization, in which the generated hydrogen covers the positive electrode, inhibiting the subsequent reaction and causing a sudden drop in electromotive force.

[0027] Furthermore, a separator that suppresses mixing of the first and second electrolyte solutions is protruded between a pair of detection electrodes formed at a distance from each other on the upper surface of the base, so that a decrease in electromotive force caused by mixing of the first and second electrolyte solutions can be suppressed. Meanwhile, since the second deliquescent material is arranged so as to cover the other detection electrode and the first deliquescent material, mixing of the first and second electrolyte solutions is not completely prevented, and the imbalance of charges generated between one detection electrode side and the other detection electrode side can be adjusted, thereby reducing a decrease in electromotive force. [Brief description of the drawings]

[0028] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a schematic configuration of a sensor according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic plan view showing a schematic configuration of the sensor main body of FIG. [Diagram 3] FIG. 3 is a schematic cross-sectional view corresponding to FIG. 1, showing a state in which the first and second deliquescent materials have absorbed moisture and are mixed together. [Figure 4] FIG. 4 is a schematic cross-sectional view showing a schematic configuration of a sensor main body according to another embodiment of the present invention. [Diagram 5] FIG. 5 is a schematic cross-sectional view showing a schematic configuration of a sensor main body according to another embodiment of the present invention. [Figure 6] FIG. 6 is a schematic cross-sectional view showing a schematic configuration of a sensor main body according to another embodiment of the present invention. [Figure 7] FIG. 7 is a schematic cross-sectional view showing a schematic configuration of a sensor main body according to another embodiment of the present invention. [Figure 8] FIG. 8 is a schematic plan view showing a schematic configuration of the sensor main body of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0030] [First embodiment] FIG. 1 is a schematic cross-sectional view showing the schematic configuration of a sensor according to one embodiment of the present invention, and FIG. 2 is a schematic plan view showing the schematic configuration of a sensor body 2 of FIG.

[0031] The sensor 1 of this embodiment detects moisture that has infiltrated into a space to be detected, and is equipped with a sensor body 2 that generates an electromotive force in response to the infiltrating moisture, and a judgment unit 3 that judges whether or not moisture has infiltrated based on the electromotive force generated in the sensor body 2.

[0032] The sensor body 2 has a base 4 having a rectangular outer shape when viewed from above. This base 4 has a flat, rectangular bottom wall portion 4a when viewed from above, a peripheral wall portion 4b formed so as to protrude upward from the outer periphery of the bottom wall portion 4a, and a separator 4c having a rectangular cross section formed so as to protrude upward from the center of the bottom wall portion 4a.

[0033] First and second recesses 21, 22 each having a rectangular shape in plan view are defined in the base 4 by the bottom wall 4a, a peripheral wall 4b on the outer periphery of the bottom wall 4a, and a separator 4c in the center of the bottom wall 4a.

[0034] The separator 4c is formed in the center of the long side direction (left and right direction in FIG. 2) of the rectangular bottom wall 4a in plan view along the short side direction (up and down direction in FIG. 2) so as to connect the opposing peripheral wall portions 4b. The first and second recesses 21, 22 are rectangular in plan view and are partitioned symmetrically by the separator 4c.

[0035] A pair of detection electrodes 5, 6 are formed on the inner bottom surfaces of the first and second recesses 21, 22. The detection electrodes 5, 6 extend toward the short sides from the separator 4c in the center at a slight interval. That is, the separator 4c is provided so as to protrude into the region between the pair of detection electrodes 5, 6.

[0036] The pair of detection electrodes 5, 6 extend toward the short sides and further extend to the inner surface and upper surface of the peripheral wall portion 4b connected to each short side. Conductive wires 9, 10 are electrically connected to the upper surface of each peripheral wall portion 4b, which is the extension end of each detection electrode 5, 6, and each detection electrode 5, 6 is electrically connected to the determination unit 3 via each wire 9, 10.

[0037] The detection electrodes 5 and 6 are each made of a metal having a different ionization tendency. For example, it is formed by a vacuum deposition method, a sputtering method, or a plating method.

[0038] Each of the detection electrodes 5 and 6 has a width slightly narrower than the width along the short side direction (the vertical direction in FIG. 2) of the first and second recesses 21 and 22 which are rectangular in plan view.

[0039] The first and second recesses 21 and 22 contain first and second deliquescent materials 11 and 12, respectively, which absorb moisture and dissolve in the absorbed moisture to become first and second electrolyte solutions.

[0040] The sensor body 2 is installed in a detection target space in which moisture that has infiltrated therein is to be detected. The detection target space is, for example, the internal space of a package that houses various elements that are degraded by moisture that has infiltrated therein and whose characteristics change.

[0041] This package is, for example, a package for various electronic devices such as an optical transceiver, and is a package that is hermetically sealed with an inert gas such as nitrogen gas or dry air.

[0042] The sensor body 2 installed in the package of such an electronic device is small. In this embodiment, the size of the base body 4, which has a rectangular outer shape in a plan view, is, for example, 3 mm×2 mm. The outer size of the sensor body 2 is not particularly limited, and is appropriately selected depending on the size of the detection target space in which the sensor body 2 is installed.

[0043] The substrate 4 is made of an insulating material such as quartz, glass, ceramic, or glass epoxy.

[0044] In this embodiment, the base 4 is made of Z-plate quartz crystal and is roughly rectangular, with the central separator 4c, the peripheral wall portion 4b on the outer periphery, and the first and second recesses 21, 22 defined thereby being integrally formed by etching.

[0045] The quartz crystal is not limited to Z-cut quartz crystal, but may be AT-cut quartz crystal or quartz crystal with other cutting angles.

[0046] The first deliquescent material 11 is accommodated in the first recess 21 of the base 4, which is partitioned by the separator 4c, so as to cover one of the detection electrodes 5, and its upper surface is lower than the height of the separator 4c. This prevents the first electrolyte solution, which is generated when the first deliquescent material 11 absorbs moisture, from moving directly to the other detection electrode 6 across the separator 4c, and prevents the metal ions contained in the first electrolyte solution from directly transferring electrons e from the other detection electrode 6, as described later. - They are trying to prevent people from receiving the message.

[0047] The second deliquescent material 12 is mostly contained within the second recess 22 of the base 4 separated by the separator 4c so as to cover the other detection electrode 6, and a portion of it is positioned so as to extend beyond the separator 4c and cover the first deliquescent material 11.

[0048] The first deliquescent material 11 absorbs moisture, dissolves in the absorbed moisture, and becomes a first electrolyte solution, which spreads over one of the detection electrodes 5. The second deliquescent material 12 absorbs moisture, dissolves in the absorbed moisture, and becomes a second electrolyte solution, which spreads over the other detection electrode 6, and a part of the second deliquescent material 12 spreads over the first deliquescent material 11.

[0049] Since the first and second deliquescent substances 11, 12 are contained in the respective recesses 21, 22 of the base 4, when they absorb moisture and become the first and second electrolyte solutions, they remain within the respective recesses 21, 22, and the first and second electrolyte solutions can be prevented from flowing out to the outside of the detection electrodes 5, 6.

[0050] In order to allow the first and second deliquescent substances 11, 12 that have absorbed moisture to spread smoothly over the detection electrodes 5, 6 as the first and second electrolyte solutions, the surfaces of the detection electrodes 5, 6 may be cleaned in advance by ashing or UV irradiation to improve wettability before the first and second deliquescent substances 11, 12 are placed.

[0051] The separator 4c separating the first and second recesses 21, 22 of the substrate 4 basically has the function of preventing the first and second electrolyte solutions produced when the first and second deliquescent substances in each recess 21, 22 absorb moisture from mixing.

[0052] The first and second deliquescent materials in the first and second recesses 21 and 22 absorb moisture to generate first and second electrolyte solutions, respectively. When a chemical battery is constructed as described below, the first and second electrolyte solutions are mixed, and the metal ions of the first electrolyte solution contained in the mixed electrolyte solution are directly converted into electrons e at the other detection electrode 6. - This is because if the external circuit, the determining unit 3, receives this signal, no current will flow to the determining unit 3, which is an external circuit.

[0053] On the other hand, if the first and second electrolyte solutions were completely immiscible, when a chemical battery is constructed, the number of cations will increase on the other detection electrode 6 side, which will become the negative electrode, as described below, and the number of anions will increase on the other detection electrode 5 side, which will become the positive electrode, resulting in an imbalance of charges and a decrease in electromotive force.

[0054] Therefore, in this embodiment, as described above, a portion of the second deliquescent material 12 is disposed so as to extend beyond the separator 4c and cover the first deliquescent material 11, so that when a chemical battery is constructed, the first and second electrolyte solutions are allowed to mix, thereby making it possible to adjust the charge balance.

[0055] The basic function of the separator 4c is to suppress mixing of the first and second electrolyte solutions generated when the first and second deliquescent materials 11, 12 absorb moisture. Therefore, when the amounts of the first and second deliquescent materials 11, 12 contained in the first and second recesses 21, 22 are small, the height of the separator 4c from the bottom wall portion 4a may be lower than the height of the peripheral wall portion 4b from the bottom wall portion 4a.

[0056] As the first deliquescent material 11 that absorbs moisture to become the first electrolyte solution, for example, copper chloride (CuCl2) is preferable.

[0057] The second deliquescent material 12 that absorbs moisture to become the second electrolyte solution is preferably any one of calcium chloride (CaCl2), sodium hydroxide (NaOH), magnesium chloride (MgCl2), citric acid (C6H8O7), and potassium carbonate (K2O3), which have high deliquescent properties and easily absorb moisture to become an electrolyte solution. The second deliquescent material 12 in this embodiment is calcium chloride, which has very high deliquescent properties and is inexpensive.

[0058] Calcium chloride has a very high deliquescent property and easily becomes an electrolyte solution. Therefore, by covering the first deliquescent material 11 with calcium chloride, which is the second deliquescent material 12, as described above, the entire material can be filled with the second electrolyte solution, which is generated by the second deliquescent material 12 absorbing moisture, before the first deliquescent material 11 absorbs moisture and changes into the first electrolyte solution.

[0059] The first and second deliquescent materials 11, 12 can be accommodated in the first and second recesses 21, 22 as follows. That is, under an inert gas atmosphere such as nitrogen gas or a dry air atmosphere, the first deliquescent material 11 in a solid state is accommodated in the first recess 21 so as to cover one of the detection electrodes 5. Next, the second deliquescent material 12 in a solid state is accommodated in the second recess 22 so as to cover the other detection electrode 6 and to cover a part of the first deliquescent material 11.

[0060] When the work cannot be performed in an inert gas atmosphere such as nitrogen gas or a dry air atmosphere, the connection between each of the detection electrodes 5, 6 and the determination unit 3 is cut off to inhibit the movement of electrons, and the work is performed as follows. That is, in an atmosphere containing moisture, first, a first electrolyte solution in which the first deliquescent material 11 is dissolved in water is applied to one of the detection electrodes 5 in the first recess 21, and the sensor body 2 is heated to evaporate the water in the first electrolyte solution to form the first deliquescent material 11 in a solid state. Thereafter, a second electrolyte solution in which the second deliquescent material 12 is dissolved in water is applied to the other detection electrode 6 in the second recess 22 and to a part of the first deliquescent material 11 so as to overlap therewith, and the sensor body 2 is heated to evaporate the water in the second electrolyte solution to form the second deliquescent material 12 in a solid state. By this heating, even if a part of the first deliquescent material 11 is the first electrolyte solution when the second electrolyte solution is applied, the water evaporates and the first deliquescent material 11 returns to its original solid state.

[0061] In this manner, under an atmosphere containing moisture, the first and second deliquescent substances 11, 12 are treated as first and second electrolyte solutions in solution state, and finally, under an inert gas atmosphere or a dry air atmosphere, the first and second electrolyte solutions are heated to evaporate the moisture therein to turn them into solid-state deliquescent substances 11, 12, and each of the detection electrodes 5, 6 is connected to the determination unit 3.

[0062] One of the pair of detection electrodes 5, 6, the detection electrode 5, is made of a precious metal such as gold (Au) or platinum (Pt), and in this embodiment, gold. This one detection electrode 5 may be made of copper (Cu) instead of gold (Au). The other detection electrode 6 is made of a base metal with a high ionization tendency, such as zinc (Zn), iron (Fe), or nickel (Ni), and in this embodiment, zinc.

[0063] In order to improve adhesion between the base 4 made of quartz crystal and the metals constituting each of the detection electrodes 5, 6, it is preferable to form a base metal film such as chromium (Cr) on the base 4, and then form the metals constituting each of the detection electrodes 5, 6 on the base metal film.

[0064] The sensor 1 of this embodiment is incorporated into the internal space of a package of an electronic device, and the wires 9, 10 connected to the detection electrodes 5, 6 are connected to, for example, a determination unit 3 provided in the electronic device, and the sensor 1 is hermetically sealed. Note that the determination unit 3 only needs to be able to determine whether or not an electromotive force is generated between the pair of detection electrodes 5, 6, and may be housed within the package of the electronic device, or may be installed outside the package.

[0065] The sensor 1 is assembled in an internal space of the package of the electronic device under an inert gas atmosphere or a dry air atmosphere. When the assembly is performed under an atmosphere containing moisture, the first and second deliquescent materials 11 and 12 are treated as the first and second electrolyte solutions in a solution state as described above, and finally, the first and second electrolyte solutions are heated under an inert gas atmosphere or a dry air atmosphere to evaporate the moisture in the solutions to turn them into the deliquescent materials 11 and 12 in a solid state, and the detection electrodes 5 and 6 are connected to the determination unit 3.

[0066] In this embodiment, when air containing moisture invades the space to be detected, the sensor body 2 forms a chemical battery as described below. At this time, an electromotive force, for example, an electromotive force of about 1.5 V, is generated between one detection electrode 5, which serves as the positive electrode, and the other detection electrode 6, which serves as the negative electrode. This electromotive force allows the determination unit 3 provided in the electronic device to detect the intrusion of moisture, and it is possible to light up an appropriate notification unit, for example, a light-emitting element (LED), to notify the intrusion of moisture.

[0067] In this embodiment, the metal constituting one of the detection electrodes 5 is a first metal M1, and its ionization tendency is I M1 The metal constituting the other detection electrode 6 is the second metal M2, and its ionization tendency is I M2 The metal contained in the first electrolyte solution and precipitated on one side of the detection electrode 5 is designated as the third metal M3, and its ionization tendency is I M3 and hydrogen ionization tendency is I H Then, the ionization tendency I M1 , I M2 , I M3 , I HThe magnitude relationship between these is as follows: Hydrogen ions are contained in the electrolyte solution that is produced when water is absorbed.

[0068] I M2 >I H >I M3 >I M1 As described above, the first metal M1 constituting one detection electrode 5 is gold (Au), the second metal M2 constituting the other detection electrode 6 is zinc (Zn), and the third metal M3 contained in the first electrolyte solution and precipitated on the side of one detection electrode 5 is copper (Cu). Therefore, their ionization tendencies I Au , I Zn , I Cu The magnitude relationship is shown below.

[0069] I Zn >I H >I Cu >I Au In this embodiment, when air containing moisture enters the detection space, the first deliquescent substance 11, copper chloride, and the second deliquescent substance 12, calcium chloride, absorb the moisture and dissolve in the absorbed moisture to become first and second electrolyte solutions, which spread over each of the detection electrodes 5 and 6.

[0070] Of the pair of detection electrodes 5, 6, the zinc of the other detection electrode 6 having a greater ionization tendency dissolves into the second electrolyte solution.

[0071] At this time, zinc Zn is oxidized to zinc ions Zn 2+ and electron e - That is, the other detection electrode 6 emits electrons e - It becomes a negative electrode that releases

[0072] At the negative electrode, the following reaction occurs:

[0073] Zn → Zn 2+ +2e - The electron e generated at the other detection electrode 6 -flows into one of the detection electrodes 5 via the wire 10, the determination unit 3, and the wire 9.

[0074] At this time, electron e - When the liquid passes through the determination unit 3, the intrusion of moisture is detected.

[0075] At one detection electrode 5, the electrons e - The first electrolyte solution contains copper ions, which are cations with a low ionization tendency. 2+ is electron e - The electrons react with the gold and react with the metal, and the metal is reduced to precipitate copper (Cu). - It becomes the positive electrode that receives

[0076] At the positive electrode, the following reaction occurs:

[0077] Cu 2+ +2e - →Cu As described above, in this embodiment, when air containing moisture enters the detection target space, a chemical battery similar to a Daniel cell, as shown in the following battery formula, is formed.

[0078] (-)Zn|CaCl2(aq)|CuCl2(aq)|Au(+) At this time, an electromotive force is generated between one detection electrode 5 which serves as a positive electrode and the other detection electrode 6 which serves as a negative electrode, and this electromotive force causes the determination unit 3 to determine that moisture has infiltrated.

[0079] In this embodiment, the separator 4c separating the first and second recesses 21 and 22 of the base 4 can prevent the first and second electrolyte solutions generated by the first and second deliquescent substances absorbing moisture in the first and second recesses 21 and 22 from mixing. This prevents the copper ions Cu contained in the first electrolyte solution of the mixed electrolyte solution from being mixed. 2+ However, electrons e - Therefore, it is possible to prevent the original electromotive force from being not obtained between the pair of detection electrodes 5 and 6 due to the reception of the electric current.

[0080] The sensor 1 of the present embodiment only needs to detect and report moisture, and does not need to generate power for a long period of time like a general chemical battery, so it can fully function as a sensor.

[0081] As time passes, the other detection electrode 6, which is the negative electrode, becomes positive. 2+ The negative ion Cl increases on the positive detection electrode 5 side. - In this embodiment, however, as described above, a part of the second deliquescent material 12 is disposed so as to extend beyond the separator 4c and cover the first deliquescent material 11.

[0082] As a result, the first and second deliquescent materials 11 and 12 gradually mix with each other to produce a mixed electrolyte solution 25 as shown in FIG. 3. The mixing of the first and second electrolyte solutions causes zinc ions Zn 2+ is the chlorine ion Cl from the negative electrode to the positive electrode. - can move through the solution from the positive electrode to the negative electrode, adjusting the balance of electric charges and suppressing a decrease in electromotive force.

[0083] In Fig. 1, the surfaces of the first and second deliquescent materials 11 and 12 in the solid state are flat, while in Fig. 3, the surface of the electrolyte solution 25 in which the first and second electrolyte solutions are completely mixed is rounded and curved. This is an exaggerated example, and depending on the amounts of the first and second deliquescent materials 11 and 12, the surfaces may be flat, curved, or uneven, regardless of whether they are in the solid state or solution state.

[0084] The space to be detected is the internal space of a package of an electronic device that is hermetically sealed with an inert gas or dry air. If the sensor 1 of this embodiment detects the intrusion of moisture-containing air into the internal space of the package after a long period of time has passed, it can be determined that the moisture-containing air has infiltrated into the package due to deterioration of the electronic device over time, and that the electronic device has reached the end of its life.

[0085] Furthermore, if the intrusion of moisture-containing air is detected at an early stage, it can be determined that the airtight sealing of the package of the electronic device is incomplete.

[0086] In this manner, the ingress of moisture-laden air into the hermetically sealed package of the electronic device can be monitored.

[0087] Conventional humidity sensors detect changes in capacitance or impedance between two electrodes, so a voltage must be constantly applied between the two electrodes, resulting in power consumption.

[0088] In contrast, the sensor 1 of the present embodiment can detect moisture that has infiltrated into the detection target space without consuming power, and does not require a power source.

[0089] In addition, the sensor body 2 has a simple configuration in which the first and second deliquescent materials 11 and 12, which become the first and second electrolyte solutions, are placed in the first and second recesses 21 and 22 so as to cover the pair of detection electrodes 5 and 6 on the base 4, so that it is easy to make it compact and inexpensive.

[0090] Furthermore, a chemical battery similar to a Daniel cell is configured, and copper is precipitated on one of the detection electrodes 5, which is the positive electrode, and hydrogen H2 is not generated at the positive electrode as in a Volta cell. Therefore, in this embodiment, unlike a Volta cell, hydrogen generated at the positive electrode accumulates around the positive electrode, making it difficult to transfer electrons, and polarization does not occur, in which the electromotive force drops suddenly.

[0091] In addition, the separator 4c separating the first and second recesses 21 and 22 of the base 4 can suppress the mixing of the first and second electrolyte solutions generated when the first and second deliquescent substances in the first and second recesses 21 and 22 absorb moisture. 2+ However, electrons e - This can prevent the electromotive force from being lost.

[0092] Furthermore, since the first and second electrolyte solutions are allowed to mix gradually rather than being completely prevented from mixing, the mixing allows for the movement of ions, making it possible to adjust the charge balance and suppress a decrease in electromotive force.

[0093] [Second embodiment] FIG. 4 is a schematic cross-sectional view showing the schematic configuration of a sensor body 21 according to another embodiment of the present invention, and parts corresponding to those in FIG. 1 are given the same reference numerals.

[0094] In this embodiment, the sensor body 21 has a moisture-permeable lid 13 bonded to the upper surface of the peripheral wall portion 4b of the base 4, for example by an adhesive, so as to cover the first and second deliquescent substances 11, 12 contained in the first and second recesses 21, 22 of the base 4.

[0095] The lid 13 is preferably made of a moisture-permeable resin, such as a thermoplastic resin. The resin constituting the lid 13 is preferably, for example, polyimide, cellophane, polyethylene, acrylic, or the like, and in this embodiment, the lid 13 is made of polyimide.

[0096] The other configuration is similar to that of the sensor 1 in FIG.

[0097] In this manner, the first and second deliquescent materials 11, 12 in the first and second recesses 21, 22 of the base 4 are covered by the moisture-permeable lid 13. Therefore, even if the task of housing the sensor body 21 in the package of an electronic device cannot be performed in an inert gas atmosphere or a dry air atmosphere, moisture in the air will not penetrate through the lid 13 and into the first and second recesses 21, 22 of the base 4 within the relatively short time required for the task, for example, within a few hours.

[0098] On the other hand, in applications such as detecting moisture contained in the air that has entered the package as the package of an electronic device deteriorates over time, it is not necessary to immediately detect and report the intrusion of moisture-containing air into the package, and it is acceptable for there to be a time delay sufficient for the moisture to penetrate the moisture-permeable lid 13.

[0099] Therefore, this is suitable for cases where it is necessary to install the sensor body 21 in the internal space of the package of an electronic device in the air, rather than in an inert gas or dry air atmosphere.

[0100] By selecting the material, thickness, etc. of the lid 13, the time it takes for moisture that has entered the package of the electronic device to permeate the lid 13 can be changed.

[0101] Furthermore, the first and second deliquescent materials 11, 12 in the first and second recesses 21, 22 can be physically protected by the lid 13, making them easy to handle.

[0102] The lid 13 may be provided with a large number of minute through holes through which air containing moisture can pass, so that intrusion of air containing moisture can be detected quickly.

[0103] Furthermore, a plurality of shallow grooves may be formed on the upper surface of the separator 4c so as to connect the first and second recesses 21, 22 on both sides of the separator 4c. This allows the second deliquescent material 12 in the second recess 22 to easily move toward the first recess 21 through the plurality of grooves, so that it is not necessary to dispose the second deliquescent material 12 to cover the first deliquescent material 11 beyond the separator 4c, and accordingly the height of the sensor body 21 can be reduced to achieve a low profile.

[0104] [Third embodiment] FIG. 5 is a schematic cross-sectional view showing a schematic configuration of a sensor body 22 according to still another embodiment of the present invention, and parts corresponding to those in FIG. 4 above are given the same reference numerals.

[0105] In each of the above-described embodiments, the pair of detection electrodes 5 and 6 are electrically connected to the determination unit 3 via conductive wires 9 and 10, respectively.

[0106] In this embodiment, the detection electrodes 5, 6 on the upper surface of the base 42 are conductively connected to the external connection terminals 16, 17 on the outer bottom surface of the base 42 by internal conductors 14, 15 that penetrate the bottom wall portion 42a.

[0107] That is, in this embodiment, the sensor body 22 is electrically connected to a determination unit 3 provided in the electronic device by bonding each of the external connection terminals 16, 17 to a substrate within a package, which is the detection target space of the electronic device, for example.

[0108] The other configuration is similar to that of the embodiment in FIG.

[0109] [Fourth embodiment] FIG. 6 is a schematic cross-sectional view showing the schematic configuration of a sensor body 23 according to still another embodiment of the present invention, and parts corresponding to those in FIG. 4 above are given the same reference numerals.

[0110] The substrate 43 of the sensor body 23 in this embodiment is made of quartz, which is an anisotropic etching material that is easily etched in specific crystal planes, as in the above embodiments, and in this example, an AT-cut quartz plate is used. Figure 6 shows the crystal axes X, Y', and Z' of this AT-cut quartz plate, with the crystal axis X being +X on the front side of the paper and -X on the back side of the paper.

[0111] In this embodiment, by utilizing the etching anisotropy of the quartz plate, the surface of separator 43c facing the other detection electrode 6 forms inclined surface 43c1 that is inclined downward toward the other detection electrode 6 side.

[0112] In this way, the surface of the separator 43c facing the other detection electrode 6 is an inclined surface 43c1 that inclines downward toward the other detection electrode 6, so that cations in the second electrolyte solution generated when the second deliquescent material 12 absorbs moisture can easily move along the inclined surface 43c1 toward one detection electrode 5. Metal ions (cations) in the first electrolyte solution generated when the first deliquescent material 11 on one detection electrode 5 absorbs moisture are less likely to move across the separator 43c to the other detection electrode 6 on the opposite side because the side surface of the separator 43c facing the one detection electrode 5 is not an inclined surface.

[0113] This promotes the movement of cations in the second electrolyte solution, which is generated when the second deliquescent material 12 absorbs moisture, to one of the detection electrodes 5, contributing to the generation of a stable electromotive force. In addition, the deposition of metal ions in the first electrolyte solution, which is generated when the first deliquescent material 11 absorbs moisture, at the other detection electrode 6 can be suppressed, thereby suppressing a decrease in the electromotive force.

[0114] The other configuration is similar to that of the embodiment in FIG.

[0115] In another embodiment of the present invention, the surface of the separator facing one of the detection electrodes 5 may be inclined upward toward the one of the detection electrodes 5, that is, the inclined surface may be inclined so as to protrude upward toward the one of the detection electrodes 5.

[0116] According to this configuration, the first electrolyte solution, which is generated when the first deliquescent material 11 covering one detection electrode 5 serving as the positive electrode absorbs moisture, can be prevented from moving over the inclined surface of the separator toward the other detection electrode 6. This makes it possible to prevent metal ions contained in the first electrolyte solution from moving toward the other detection electrode 6 and directly receiving electrons from the other detection electrode 6, thereby reducing the decrease in electromotive force.

[0117] [Fifth embodiment] Fig. 7 is a schematic cross-sectional view showing a schematic configuration of a sensor body 24 according to another embodiment of the present invention, and Fig. 8 is a schematic plan view thereof. Fig. 7 is a cross-sectional view taken along the cutting line AA in Fig. 8. In Fig. 8, the outer shape of the lid body 134 is indicated by a dashed line.

[0118] In the sensor main body 2, 21-23 of each of the above embodiments, the outer shape of the base 4, 42-43 in plan view is rectangular, but in this embodiment, the outer shape of the base 44 in plan view is circular. That is, the base 44 includes a bottom wall portion 44a that is circular in plan view, a peripheral wall portion 44b that is annular in plan view and stands on the outer periphery of the bottom wall portion 44a, and a separator 44c that is approximately annular in plan view inside the peripheral wall portion 44b. The lid body 134 attached to the base 44 is circular in plan view.

[0119] The inner peripheral surface of the separator 44c is circular in plan view and is concentric with the base 44. The outer peripheral surface of the separator 44c is generally circular in plan view, and one side in the circumferential direction (the right side in FIGS. 7 and 8) is pulled outward and connected to the peripheral wall portion 44b via a step portion 44d.

[0120] One of the detection electrodes 54 has a detection electrode portion 54a which is circular in plan view and is partitioned by the inner surface of the separator 44c, and a connection electrode portion 54b which is pulled out from the one circumferential side of the detection electrode portion 54a and connected to the step portion 44d and the upper surface of the peripheral wall portion 44b.

[0121] The other detection electrode 64 includes a detection electrode portion 64a that is C-shaped in a planar view and concentrically formed in an area partitioned by the outer peripheral surface of separator 44c and the inner peripheral surface of peripheral wall portion 44b so as to surround separator 44c, and a connection electrode portion 64b that is extended from this detection electrode portion 64a to the upper surface of peripheral wall portion 44b on the other side (left side in Figures 7 and 8) facing the one side in the circumferential direction.

[0122] The connection electrode portion 54b drawn out from one circumferential side of the detection electrode portion 54a, which is circular in a planar view, and the connection electrode portion 64b drawn out from the other circumferential side of the detection electrode 64, which is C-shaped in a planar view, are electrically connected to a determination portion (not shown) via conductive wires 9 and 10.

[0123] The first deliquescent material 11 is disposed in a circular shape in plan view in a region that is defined by the inner circumferential surface of the separator 44c so as to cover the detection electrode portion 54a of one detection electrode 54.

[0124] The second deliquescent material 12 is arranged in a circular shape in plan view within an area partitioned by the inner surface of the peripheral wall portion 44b so as to cover the first deliquescent material 11 which is circular in plan view in the center, and to cover the detection electrode portion 64a of the other detection electrode 64 which is C-shaped in plan view.

[0125] According to this embodiment, since the one and the other detection electrode parts 54a, 64a are formed concentrically with each other, the planar shapes of the first and second electrolyte solutions generated by the first and second deliquescent materials 11, 12 absorbing moisture can be made to approach a circle by the surface tension. Therefore, the first and second electrolyte solutions can be easily spread evenly over the detection electrode parts 54a, 64a, and an electromotive force can be stably generated.

[0126] The other configuration is similar to that of the embodiment in FIG. [Explanation of symbols]

[0127] 1 Sensor 2,21~24 Sensor body 3 Judgment section 4,42~44 base 4c,44c separator 43c1 Slope 5,54 Detection electrode (one side) 6,64 Detection electrode (other side) 11,12 1st and 2nd deliquescent substances 25 Electrolyte solution 21, 22 First and second recesses 9,10 Wire 13 Lid

Claims

1. A sensor for detecting moisture in a detection target space, An insulating base, a pair of detection electrodes made of metals with different ionization tendencies formed on an upper surface of the base, a first deliquescent substance that absorbs moisture to become a first electrolyte solution, and a second deliquescent substance that absorbs moisture to become a second electrolyte solution are disposed within the detection target space; the first deliquescent material is disposed so as to cover one of the pair of detection electrodes which is a positive electrode; the first electrolyte solution contains ions of a metal that can be deposited on the one detection electrode side, the second deliquescent material is disposed so as to cover the other of the pair of detection electrodes, which is a negative electrode, and the first deliquescent material; the pair of detection electrodes are formed at an interval on the upper surface of the base, and a separator for suppressing mixing of the first electrolyte solution and the second electrolyte solution is provided in a protruding manner in the spaced apart region on the upper surface of the base; detecting intrusion of moisture into the detection target space based on an electromotive force generated between the pair of detection electrodes; A sensor characterized by:

2. The detection target space is an internal space of a package hermetically sealed with an inert gas or dry air. The sensor of claim 1 .

3. A portion of the second deliquescent material extends beyond the separator and covers the first deliquescent material. The sensor of claim 2.

4. the upper surface of the base body has a recess in which a central portion is recessed downward compared to an outer periphery, and the separator is provided in a protruding manner within the recess, and the first deliquescent material and the second deliquescent material are disposed within the recess. The sensor of claim 2.

5. The separator is integrally formed with the substrate using the same material. The sensor of claim 2.

6. the base is made of an anisotropic etching material, and a surface of the separator facing the other of the pair of detection electrodes is an inclined surface that slopes downward toward the other detection electrode. The sensor of claim 5.

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