Sensor

Abstract

To provide a sensor that can detect water content without consuming power.SOLUTION: A pair of detection electrodes 5, 6 formed of metals different in ionization tendency, and first and second deliquescence substances 11, 12 absorbing water content to be first and second electrolytic solutions are installed inside a detection target space. The first deliquescence substance 11 is arranged to cover one detection electrode 5 to be a positive electrode. The first electrolytic solution includes metal ions that can be deposited on one detection electrode 5. The second deliquescence substrate 12 is arranged to cover the other detection electrode 6 to be a negative electrode and the first deliquescence substance 11. The sensor detects infiltration of water content into the detection target space on the basis of electromotive force generated 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, and includes a pair of detection electrodes made of metals with different ionization tendencies, 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, disposed inside the space to be detected, the first deliquescent substance being disposed so as to cover one of the pair of detection electrodes which is the positive electrode, the first electrolyte solution containing ions of a metal that can be precipitated on the one detection electrode side, and the second deliquescent substance being disposed so as to cover the other of the pair of detection electrodes which is the negative electrode and the first deliquescent substance, and detects the intrusion of moisture into the space to be detected based on the 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 higher ionization tendency, dissolves into the second electrolyte solution to become metal ions and emits electrons, causing the other detection electrode to become the negative electrode. The electrons emitted from the negative electrode flow into one detection electrode, which becomes the positive electrode, and combine with metal ions in the first electrolyte solution, which have a lower ionization tendency, to precipitate metal. 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] 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 makes it possible to prevent polarization, which occurs in a Voltaic cell when the generated hydrogen covers the positive electrode, inhibiting the subsequent reaction and causing a sudden drop in electromotive force.

[0012] (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.

[0013] 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.

[0014] (3) In another embodiment of the present invention, the second deliquescent substance is any one of calcium chloride, sodium hydroxide, magnesium chloride, citric acid, or potassium carbonate.

[0015] According to this embodiment, calcium chloride, sodium hydroxide, magnesium chloride, citric acid, and potassium carbonate, which have high deliquescent properties and easily absorb moisture to become an electrolyte solution, can be suitably used as the deliquescent substance.

[0016] (4) In yet another embodiment of the present invention, one of the pair of detection electrodes, which serves as the positive electrode, is made of a metal selected from the group consisting of gold and platinum, and the other detection electrode, which serves as the negative electrode, is made of a metal selected from the group consisting of zinc, iron, and nickel.

[0017] According to this embodiment, one of the detection electrodes, which serves as the positive electrode that receives electrons, can be made of gold or platinum, which have a low ionization tendency and are less susceptible to deterioration, and the other detection electrode, which serves as the negative electrode that emits electrons, can be made of zinc, iron, or nickel, which have a high ionization tendency.

[0018] (5) In one embodiment of the present invention, the metal that can be deposited on the one detection electrode side is copper.

[0019] According to this embodiment, copper ions, which are metal ions contained in the first electrolyte solution, combine with electrons to deposit copper on the side of one detection electrode, which serves as the positive electrode. This allows the generated electromotive force to be maintained for a longer period of time than in a voltaic cell, in which hydrogen is generated at the positive electrode, covering the positive electrode and inhibiting the reaction, causing polarization in which the electromotive force drops rapidly.

[0020] (6) In another embodiment of the present invention, the metal constituting the one detection electrode is a first metal M1, the metal constituting the other detection electrode is a second metal M2, the metal capable of being deposited on the one detection electrode side is a third metal M3, and the ionization tendencies of the first metal M1, the second metal M2, and the third metal M3 are respectively set to I M1 , I M2 , I M3 and the ionization tendency of hydrogen I H Then, the ionization tendency I M1 , I M2 , I M3 , I H satisfies the following magnitude relations:

[0021] I M2 >I H >I M3 >I M1 According to this embodiment, when the first and second deliquescent materials absorb moisture and become the first and second electrolyte solutions, the second metal M2 constituting the other detection electrode, which has a greater ionization tendency, dissolves into the second electrolyte solution. At this time, electrons emitted from the other detection electrode, which is the negative electrode, flow to one detection electrode, which is the positive electrode, and the third metal ions contained in the first electrolyte solution receive the flowing electrons, causing the third metal M3 to precipitate on one detection electrode, forming a chemical battery similar to a Daniel cell.

[0022] (7) In yet another embodiment of the present invention, an insulating substrate on which the pair of detection electrodes are formed is placed inside the space to be detected, the substrate has a recess in which the central portion is recessed downward compared to the outer periphery, and the first deliquescent substance and the second deliquescent substance are arranged within the recess.

[0023] According to this embodiment, the insulating base on which the pair of detection electrodes are formed has a recess that is recessed downward in the center, and the first and second deliquescent substances are disposed in this recess. Therefore, the first and second electrolyte solutions produced when the first and second deliquescent substances absorb moisture can be stably retained in the recess.

[0024] (8) In one embodiment of the present invention, the substrate is made of quartz or glass.

[0025] According to this embodiment, the material of the base can be quartz or glass, which is resistant to the chemicals and the like used in forming the recesses and is easy to process. Effect of the Invention

[0026] 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.

[0027] 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.

[0028] 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. [Brief description of the drawings]

[0029] [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 deliquescent material has absorbed moisture. [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. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0031] [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.

[0032] 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.

[0033] The sensor body 2 comprises a base 4 having a rectangular outer shape in a planar view and a recess 8, a pair of detection electrodes 5, 6 formed on the upper surface of the base 4, a first deliquescent material 11 arranged on one of the detection electrodes 5, and a second deliquescent material 12 arranged on the other detection electrode 6 and a portion of the first deliquescent material 11.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] The base 4 is made of an insulating material such as quartz, glass, ceramic, or glass epoxy. In this embodiment, the base 4 is made of quartz and has a rectangular plate shape. The base 4 has a rectangular recess 8 in plan view, recessed downward from the outer periphery, formed in the center by etching. The base 4 has a rectangular bottom wall 4a in plan view and a rectangular annular peripheral wall 4b in plan view that is connected to the outer periphery of the bottom wall 4a, and the recess 8 is formed by the bottom wall 4a and the peripheral wall 4b.

[0038] The pair of detection electrodes 5, 6, which are rectangular in plan view, are formed on the inner bottom surface of the recess 8, which is rectangular in plan view and extend from the center in the long side direction (left and right direction in Figs. 1 and 2) toward the opposing short sides at a distance from each other. Each detection electrode 5, 6 extends toward each short side and further extends 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.

[0039] Each of the detection electrodes 5 and 6, which is rectangular in plan view, has a width slightly narrower than the width along the short side direction (the vertical direction in FIG. 2) of the recess 8, which is rectangular in plan view.

[0040] The detection electrodes 5 and 6 are made of metals having different ionization tendencies, and are formed by, for example, vacuum deposition, sputtering, or plating.

[0041] The first and second deliquescent materials 11 and 12 absorb moisture and dissolve in the absorbed moisture to become an electrolyte solution.

[0042] The first deliquescent material 11 is disposed in the recess 8 of the base 4 so as to cover one of the detection electrodes 5. This first deliquescent material 11 is disposed at a distance from the other detection electrode 6 so as not to come into contact with the other detection electrode 6.

[0043] The first deliquescent material 11 is arranged away from the other detection electrode 6 in this manner in order to secure time for the first electrolyte solution generated by absorbing moisture to reach the other detection electrode 6. Until the first electrolyte solution generated by absorbing moisture reaches the other detection electrode 6, electrons flow from the other detection electrode 6 to one detection electrode 5 via the determination unit 3, as described below. However, when the first electrolyte solution reaches the other detection electrode 6, metal ions contained in the first electrolyte solution directly receive electrons at the other detection electrode 6, and electrons no longer flow to the determination unit 3, which is an external circuit.

[0044] The second deliquescent material 12 is disposed in the recess 8 of the base 4 so as to cover the other detection electrode 6 and to cover a part of the first deliquescent material 11. The second deliquescent material 12 is disposed so as to fill the space between the first deliquescent material 11 and the other detection electrode 6.

[0045] Since the first and second deliquescent substances 11, 12 are contained in the recessed portion 8 of the base body 4, when they absorb moisture and become the first and second electrolyte solutions, they remain within the recessed portion 8, thereby preventing the first and second electrolyte solutions from flowing out to the outside of the detection electrodes 5, 6.

[0046] 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 also over the first deliquescent material 11.

[0047] 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.

[0048] As the first deliquescent material 11 that absorbs moisture to become the first electrolyte solution, for example, copper chloride (CuCl2) is preferable.

[0049] 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 high deliquescent properties and is inexpensive.

[0050] The first and second deliquescent materials 11, 12 can be accommodated in the recess 8 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 recess 8 so as to cover one of the detection electrodes 5. Next, the second deliquescent material 12 in a solid state is accommodated in the recess 8 so as to cover the other detection electrode 6 and to cover a part of the first deliquescent material 11.

[0051] When the work cannot be performed under 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, under an atmosphere containing moisture, first, a first electrolyte solution in which a first deliquescent substance 11 is dissolved in water is applied to one of the detection electrodes 5, and the sensor body 2 is heated to evaporate the moisture of the first electrolyte solution to form the first deliquescent substance 11 in a solid state. Then, a second electrolyte solution in which a second deliquescent substance 12 is dissolved in water is applied to the other detection electrode 6 and to a part of the first deliquescent substance 11 so as to overlap the other detection electrode 6 and the first deliquescent substance 11, and the sensor body 2 is heated to evaporate the moisture of the second electrolyte solution to form the second deliquescent substance 12 in a solid state. By this heating, even if a part of the first deliquescent substance 11 is the first electrolyte solution when the second electrolyte solution is applied, the moisture evaporates and the first deliquescent substance 11 returns to its original solid state.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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 M2The 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 H The magnitude relationship between these is as follows: Hydrogen ions are contained in the electrolyte solution that is produced when water is absorbed.

[0059] 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, the ionization tendency I Au , I Zn , I Cu is shown below.

[0060] 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.

[0061] Of the pair of detection electrodes 5, 6, zinc Zn of the other detection electrode 6 having a greater ionization tendency dissolves into the second electrolyte solution.

[0062] 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

[0063] At the negative electrode, the following reaction occurs:

[0064] 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.

[0065] At this time, electron e - When the liquid passes through the determination unit 3, the intrusion of moisture is detected.

[0066] 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

[0067] At the positive electrode, the following reaction occurs:

[0068] Cu 2+ +2e - →Cu As described above, in this embodiment, when moisture enters the space to be detected, a chemical battery similar to a Daniel cell, as shown in the following battery formula, is formed.

[0069] (-)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 been detected.

[0070] When the first and second deliquescent materials 11 and 12 absorb moisture and the first and second electrolyte solutions are mixed to form a mixed electrolyte solution 25 as shown in FIG. 3, or when the first electrolyte solution is generated by the first deliquescent material 11 absorbing moisture and reaches the other detection electrode 6, the mixed electrolyte solution 25 or the copper ions Cu2+ The other detection electrode 6 directly transmits electrons e - Therefore, the original electromotive force cannot be obtained between the pair of detection electrodes 5 and 6, but since the sensor 1 of this embodiment only needs to detect and notify moisture and does not need to generate power for a long period of time as in a general chemical battery, there is no problem in terms of the sensor's functionality.

[0071] 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 have absorbed moisture and are completely mixed together has a rounded curved surface. 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.

[0072] 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.

[0073] 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.

[0074] In this manner, the ingress of moisture-laden air into the hermetically sealed package of the electronic device can be monitored.

[0075] 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.

[0076] 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.

[0077] In addition, the sensor body 2 has a simple configuration in which first and second deliquescent materials 11, 12, which become the first and second electrolyte solutions, are arranged to cover a pair of detection electrodes 5, 6 on the base 4, so that it is easy to make it compact and inexpensive.

[0078] 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.

[0079] [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.

[0080] 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 recess 8 of the base 4.

[0081] 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.

[0082] The other configuration is similar to that of the sensor 1 in FIG.

[0083] In this manner, the first and second deliquescent substances 11, 12 in the recess 8 of the base 4 are covered by the moisture-permeable lid 13. Therefore, even if the work 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 enter the recess 8 of the base 4 within the relatively short time required for the work, for example, within a few hours.

[0084] 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.

[0085] Therefore, this is suitable for cases where it is necessary to install the sensor body 21 in the internal space of a package of an electronic device in the air, rather than in an inert gas or dry air atmosphere.

[0086] 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.

[0087] Furthermore, the first and second deliquescent materials 11, 12 in the recess 8 can be physically protected by the lid 13, making them easy to handle.

[0088] 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.

[0089] [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.

[0090] 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.

[0091] 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 4a2.

[0092] 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.

[0093] The other configuration is similar to that of the embodiment in FIG.

[0094] [Fourth embodiment] In each of the above-described embodiments, a flat lid 13 is attached to the upper surface of the peripheral wall portion 4b of the base 4, 42 having a recess 8 recessed downward in the center, so as to cover the first and second deliquescent substances 11, 12 contained in the recess 8.

[0095] In this embodiment, as shown in FIG. 6, a base 43 on which a pair of detection electrodes 5, 6 are formed is flat, and a lid 20 is attached to the upper surface of this base 43 so as to cover the first and second deliquescent materials 11, 12 arranged on the detection electrodes 5, 6.

[0096] The lid body 20 of this embodiment includes a flat base portion 20a and a side plate portion 20b extending downward from the peripheral portion of the base portion 20a. The lid body 20 is a cap-shaped lid body in which a recess 18 is formed by the base portion 20a and the side plate portion 20b.

[0097] In this embodiment, the cap-shaped lid 20 is bonded to the upper surface of the flat base 43 by an adhesive or the like having low moisture permeability. Since the cap-shaped lid 20 is bonded to the flat base 43 in this manner, it is possible to prevent the first and second electrolyte solutions, which are generated when the first and second deliquescent materials 11 and 12 absorb moisture, from leaking out of the lid 20.

[0098] The other configuration is similar to that of the embodiment in FIG.

[0099] [Fifth embodiment] FIG. 7 is a schematic cross-sectional view showing the general configuration of a sensor body 24 according to still another embodiment of the present invention, and parts corresponding to those in FIG. 6 are given the same reference numerals.

[0100] In this embodiment, a flat base 44 is formed with a shallow fitting groove into which the lower end of the side plate portion 20b of the cap-shaped lid 20 fits.

[0101] The lower end of the side plate portion 20b of the cap-shaped lid body 20 is fitted into a fitting groove of the flat base body 44 and joined with an adhesive or the like.

[0102] This makes it possible to reliably prevent the first and second electrolyte solutions, which are generated when the first and second deliquescent materials 11 and 12 absorb moisture, from leaking out of the lid 20.

[0103] The other configuration is similar to that of the embodiment shown in FIG. [Explanation of symbols]

[0104] 1 Sensor 2,21~24 Sensor body 3 Judgment section 4,42~44 base 5 Detection electrode (one side) 6 Detection electrode (other side) 11,12 1st and 2nd deliquescent substances 25 Electrolyte solution 8,18 Recess 9,10 Wire 13,20 Lid

Claims

1. A sensor for detecting moisture in a detection target space, A pair of detection electrodes made of metals having different ionization tendencies, 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 installed inside 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; 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. The second deliquescent substance is any one of calcium chloride, sodium hydroxide, magnesium chloride, citric acid, and potassium carbonate. The sensor of claim 2.

4. The one of the pair of detection electrodes, which is the positive electrode, is made of a metal selected from the group consisting of gold and platinum, and the other detection electrode, which is the negative electrode, is made of a metal selected from the group consisting of zinc, iron, and nickel. The sensor of claim 2.

5. The metal that can be deposited on the one detection electrode side is copper. The sensor of claim 2.

6. The metal constituting one of the detection electrodes is a first metal M1, the metal constituting the other detection electrode is a second metal M2, and the metal capable of being deposited on the one detection electrode side is a third metal M3. The ionization tendencies of the first metal M1, the second metal M2, and the third metal M3 are respectively expressed as I Ｍ１ , I Ｍ２ , I Ｍ３ and the ionization tendency of hydrogen I Ｈ Then, the ionization tendency I Ｍ１ , I Ｍ２ , I Ｍ３ , I Ｈ But it satisfies the following magnitude relationship: I Ｍ２ >I Ｈ >I Ｍ３ >I Ｍ１ 3. The sensor according to claim 1 or 2.

7. an insulating substrate on which the pair of detection electrodes are formed is placed inside the space to be detected, the base has a central portion which is recessed downward compared to an outer periphery thereof, and the first deliquescent material and the second deliquescent material are disposed in the recess. The sensor of claim 2.

8. The substrate is made of quartz or glass. The sensor of claim 7.

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