Environment diagnosis sensor, environment diagnosis sensor array, and environment diagnosis device

Abstract

An environment diagnosis sensor (11) is provided with: a pair of electrodes (1); a resistive film (2) disposed between the pair of electrodes; a protective film (3) disposed on the resistive film; and a metal thin film (4) corroded by corrosive gas. The resistive film and the metal thin film are electrically connected in parallel to each other between the pair of electrodes. The metal thin film has a first portion (41) disposed on the resistive film via the protective film.

Description

Environmental diagnostic sensor, environmental diagnostic sensor array, and environmental diagnostic device

[0001] The present disclosure relates to an environmental diagnostic sensor, an environmental diagnostic sensor array, and an environmental diagnostic device.

[0002] Electrical devices are installed and used in a variety of environments, and if corrosive gases are present in the environment in which the electrical devices are used, the circuit boards and other components contained in the electrical devices may be damaged by corrosion over time (e.g., metal wiring may be broken).To prevent such problems from occurring, environmental diagnostic sensors have been proposed for diagnosing the degree of corrosion of electrical devices in their usage environments, or the corrosivity corresponding to the degree of corrosion of electrical devices in their usage environments.

[0003] For example, in a detection device described in Japanese Patent Laid-Open No. 2014-153089 (Patent Document 1), a plurality of detection circuit lines are provided, each of which is formed by connecting a metal thin-film wiring and a fixed resistor in series, and the plurality of detection circuit lines are connected in parallel. The metal thin-film wiring of each of the plurality of detection circuit lines is made of a different metal material or has a different film thickness. With this detection device, in the environment in which the electrical device is used, the time until each metal thin-film wiring breaks due to corrosion is calculated based on the change over time in the combined resistance of the plurality of detection circuit lines, and the corrosiveness of the environment in which the electrical device is used can be determined based on the corrosion rate of each metal thin-film wiring calculated from the result.

[0004] JP 2014-153089 A

[0005] In the above-described detection device, each metal thin film wiring is arranged next to the fixed resistor on the insulating substrate so as to be electrically connected in series with the fixed resistor, and since the metal thin film wiring and the fixed resistor each require their own dedicated area, miniaturization of such a detection device is difficult.

[0006] A primary object of the present disclosure is to enable miniaturization of environmental diagnostic sensors.

[0007] The environmental diagnostic sensor according to the present disclosure includes a pair of electrodes, a resistive film disposed between the pair of electrodes, a protective film disposed on the resistive film, and a thin metal film that is corroded by a corrosive gas. The resistive film and the thin metal film are electrically connected in parallel with each other between the pair of electrodes. The thin metal film has a first portion that is disposed on the resistive film via the protective film.

[0008] According to the present disclosure, the environmental diagnostic sensor can be miniaturized.

[0009] 1 is a diagram showing an example of an environment diagnostic device according to a first embodiment. FIG. 2 is a cross-sectional view showing an example of an environment diagnostic sensor according to the first embodiment. FIG. 3 is a plan view showing an example of an environment diagnostic sensor according to the first embodiment. FIG. 4 is a diagram for explaining an example of a change over time in the combined resistance of the environment diagnostic sensor according to the first embodiment. FIG. 5 is a diagram showing an example of an environment diagnostic device according to a second embodiment. FIG. 6 is a cross-sectional view showing an example of an environment diagnostic sensor array according to the second embodiment. FIG. 7 is a diagram for explaining an example of a change over time in the combined resistance of the environment diagnostic sensor array according to the second embodiment. FIG. 8 is a cross-sectional view showing an example of an environment diagnostic sensor array according to a third embodiment. FIG. 9 is a diagram for explaining an example of a change over time in the combined resistance of the environment diagnostic sensor array according to the third embodiment. FIG. 10 is a diagram for explaining another example of a change over time in the combined resistance of the environment diagnostic sensor array according to the third embodiment. FIG. 11 is a cross-sectional view showing an example of an environment diagnostic sensor array according to a fourth embodiment. FIG. 12 is a diagram for explaining an example of a change over time in the combined resistance of the environment diagnostic sensor array according to the fourth embodiment. FIG. 13 is a diagram for explaining another example of a change over time in the combined resistance of the environment diagnostic sensor array according to the fourth embodiment. FIG. 14 is a cross-sectional view showing an example of an environment diagnostic sensor array according to a fifth embodiment. FIG. 15 is a plan view showing an example of an environment diagnostic sensor array according to the fifth embodiment. FIG. 16 is a perspective view showing an example of an environment diagnostic sensor array according to a sixth embodiment. Fig. 10 is a plan view showing an example of an environmental diagnostic sensor array according to embodiment 6. Fig. 11 is a cross-sectional view showing an example of an environmental diagnostic sensor array according to embodiment 7. Fig. 12 is a graph showing that the rate of change over time (corrosion rate) of the corrosion defect thickness (amount of corrosion) of a metal thin film changes depending on the environment.

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following, the same or corresponding parts will be denoted by the same reference numerals, and redundant description will not be repeated.

[0011] The environmental diagnostic sensor according to this embodiment is a sensor for diagnosing the corrosiveness of the environment in which an electrical device is used. The environmental diagnostic sensor according to this embodiment is included in the electrical device together with the electrical device body, for example, and is used simultaneously with the electrical device body to estimate the degree of corrosion progress of the electrical device body. The environmental diagnostic sensor according to this embodiment is mounted on, for example, a circuit board of the electrical device body. The type of electrical device is not particularly limited. The electrical device is any electrical device used in an environment where corrosive gases may be present. Note that the environmental diagnostic sensor according to this embodiment may be used separately from the electrical device.

[0012] In this embodiment, the term "corrosive gas" refers to a gas that corrodes metal parts in electrical equipment. Corrosive gases include, for example, sulfur-based gases, chlorine-based gases, and nitrogen oxides. Sulfur-based gases include hydrogen sulfide (H ２ S), sulfur dioxide (SO ２ ), Sulfur flower (S ８ ) and the like. Chlorine-based gases include chlorine gas (Cl ２ ) and nitrogen oxides (NO ｘ ) is, for example, nitrogen dioxide (NO ２ In the present embodiment, corrosion refers to the generation of corrosion products and the eventual loss of the metallic material portion. Hereinafter, the term "initial" is used to indicate the state before the environmental diagnostic sensor is exposed to the corrosive gas.

[0013] Embodiment 1 <Configuration of Environmental Diagnostic Device> As shown in Fig. 1 , an environmental diagnostic device 101 according to embodiment 1 includes, for example, an environmental diagnostic sensor 11, a power supply 20, an electric circuit including a resistance measuring device 30, and an analysis device 40.

[0014] The environmental diagnostic sensor 11 includes a pair of electrodes 1, a resistive film 2, and a thin metal film 4. The resistive film 2 is, for example, the resistive film of a fixed resistor 10. The resistive film 2 and the thin metal film 4 are electrically connected in parallel between the pair of electrodes 1. The environmental diagnostic sensor 11 is mounted on, for example, a circuit board of the main body of an electrical device. An example structure of the environmental diagnostic sensor 11 will be described later.

[0015] The power supply 20 applies a voltage between the pair of electrodes 1 of the environmental diagnostic sensor 11. The power supply 20 is included in, for example, the main body of the electrical device. Note that the power supply 20 may be a power supply independent of the main body of the electrical device. The power supply 20 may also be a battery.

[0016] The resistance measuring device 30 measures the combined resistance of the resistive film 2 and the thin metal film 4 of the environmental diagnostic sensor 11 and outputs the measurement result to the analyzing device 40. The resistance measuring device 30 includes, for example, a voltmeter 301 and an ammeter 302. The voltmeter 301 measures the voltage applied between the pair of electrodes 1 of the environmental diagnostic sensor 11 and outputs the measurement result to the analyzing device 40. The ammeter 302 measures the current flowing through the environmental diagnostic sensor 11 and outputs the measurement result to the analyzing device 40.

[0017] The analysis device 40 includes, for example, a microprocessor. The analysis device 40 identifies the degree of corrosion of the metal thin film 4 from the resistance value measured by the resistance measuring device 30. Furthermore, the analysis device 40 identifies the type of corrosive gas present in the environment based on the resistance value measured by the resistance measuring device 30 and corrosion resistance information, which will be described later. The analysis device 40 outputs the analysis results to an alarm device or the like.

[0018] <Configuration of Environmental Diagnostic Sensor> As shown in FIGS. 2 and 3, the environmental diagnostic sensor 11 includes a pair of electrodes 1, a resistive film 2, a protective film 3, a thin metal film 4, and an insulating substrate 5.

[0019] The insulating substrate 5 is an electrically insulating substrate. Examples of materials that can be used for the insulating substrate 5 include aluminum oxide (Al2O3), glass (SiO2), and a silicon wafer (Si). The insulating substrate 5 has, for example, a rectangular parallelepiped shape. The insulating substrate 5 has an upper surface (first surface), a lower surface (second surface), a first side surface, and a second side surface. The upper and lower surfaces of the insulating substrate 5 extend along a first direction DR1 and a second direction perpendicular to the first direction DR1. The first side surface and the second side surface face opposite each other in the first direction DR1. The insulating substrate 5 further has a third side surface and a fourth side surface. The third side surface and the fourth side surface each extend between the first side surface and the second side surface. The third side surface and the fourth side surface face opposite each other in the second direction.

[0020] The pair of electrodes 1 are arranged at a distance from each other on the surface of the insulating substrate 5. Each of the pair of electrodes 1 has one end located on the upper surface of the insulating substrate 5 and the other end located on the lower surface of the insulating substrate 5. The ends of the pair of electrodes 1 are arranged at a distance from each other on the upper surface of the insulating substrate 5. The other ends of the pair of electrodes 1 are arranged at a distance from each other on the lower surface of the insulating substrate 5. One of the pair of electrodes 1 covers a first side surface of the insulating substrate 5 and a portion of the first side surface of each of the upper and lower surfaces. The other of the pair of electrodes 1 covers a second side surface of the insulating substrate 5 and a portion of the second side surface of each of the upper and lower surfaces. The portion of each of the pair of electrodes 1 arranged on the lower surface of the insulating substrate 5 functions as a so-called back electrode that is electrically connected to a circuit board (e.g., a circuit board of an electrical device body) on which the environmental diagnostic sensor 11 is mounted.

[0021] Each of the pair of electrodes 1 includes, for example, an internal electrode 6, an intermediate electrode 7, and an external electrode 8. The internal electrode 6, intermediate electrode 7, and external electrode 8 are layered in this order from the surface side in a direction perpendicular to the surface of the insulating substrate 5. For example, the internal electrode 6 extends more inward than the intermediate electrode 7 and external electrode 8 on the upper surface of the insulating substrate 5. On the upper surface of the insulating substrate 5, one ends of the intermediate electrode 7 and the external electrode 8 are disposed more outward than one end of the internal electrode 6.

[0022] The internal electrode 6 is covered by the intermediate electrode 7 or the protective film 3, except for the other end that is disposed on the lower surface of the insulating substrate 5. The intermediate electrode 7 is covered by the external electrode 8. The external electrode 8 is exposed on the lower surface, first side surface, and second side surface of the insulating substrate 5. The external electrode 8 is covered by the metal thin film 4 on the upper surface of the insulating substrate 5.

[0023] The material forming the internal electrodes 6 includes, for example, silver (Ag). The material forming the intermediate electrodes 7 includes, for example, nickel (Ni). The material forming the external electrodes 8 includes, for example, tin (Sn).

[0024] The resistive film 2 is disposed between a pair of electrodes 1 on the upper surface of the insulating substrate 5. The resistive film 2 electrically connects the above-mentioned one end of each of the pair of electrodes 1. For example, the resistive film 2 is in contact with only each of the internal electrodes 6 of the pair of electrodes 1. The resistance value R of the resistive film 2 is R is the initial resistance R of the metal thin film 4 before exposure to the corrosive gas. M1 The material forming the resistive film 2 includes, for example, an oxide semiconductor. The material forming the resistive film 2 includes, for example, ruthenium oxide (RuO ２ The material for the resistive film 2 is not limited to the above materials.

[0025] The protective film 3 is disposed on the resistive film 2. The protective film 3 covers, for example, the resistive film 2. The protective film 3 covers, for example, the resistive film 2 and one end of each internal electrode 6 of the pair of electrodes 1 connected to the resistive film 2. The protective film 3 is disposed, for example, across each intermediate electrode 7 of the pair of electrodes 1. The protective film 3 is more resistant to corrosive gases than the resistive film 2. The material and thickness of the protective film 3 can be arbitrarily set as long as they can suppress corrosion of the resistive film 2 for the time from when the environmental diagnostic device 101 is exposed to the corrosive gas until the metal thin film 4 is broken due to corrosion. The material of the protective film 3 includes, for example, epoxy resin. The protective film 3 has, for example, a central portion 31 and a pair of outer edge portions 32 arranged on either side of the central portion 31 in the first direction DR1. The thickness of the central portion 31 is constant. One end of each external electrode 8 of the pair of electrodes 1 is formed, for example, on the outer edge portion of the protective film 3.

[0026] The metal thin film 4 is exposed to a corrosive gas and corrodes due to the corrosive gas. The metal thin film 4 covers parts of the pair of electrodes 1, the resistive film 2, and the protective film 3 on the upper surface of the insulating substrate 5. The metal thin film 4 has a first portion 41 disposed on the resistive film 2 via the protective film 3, and a pair of second portions 42 disposed on the pair of electrodes 1. The first portion 41 is continuous with the pair of second portions 42.

[0027] The material constituting the thin metal film 4 is selected depending on the corrosive gas to be detected by the environmental diagnosis device 101, i.e., the corrosive gas expected to be present in the environment in which the electrical device is used. For example, if the corrosive gas to be detected is sulfur dioxide or chlorine gas, the material constituting the thin metal film 4 preferably contains Ag. If the corrosive gas to be detected is hydrogen sulfide, sulfur dioxide, or nitrogen dioxide, the material constituting the thin metal film 4 preferably contains Cu.

[0028] The thickness of the metal thin film 4 can be set arbitrarily. For example, the thickness of the metal thin film 4 corresponds to the corrosion defect thickness expected after a predetermined time has elapsed based on the expected degree of corrosion of the electrical device in the usage environment or the corrosiveness of the usage environment of the electrical device. This will be described in detail later.

[0029] 4, in the environmental diagnostic device 101, the combined resistance value of the resistive film 2 and the thin metal film 4 changes as the corrosion of the thin metal film 4 progresses. The initial combined resistance value R C1 is the resistance value R of the resistive film 2 R , the initial resistance value R of the metal thin film 4 M1 When this is done, R M1 ×R R / (R M1 +R R The initial resistance value R of the metal thin film 4 before the environmental diagnostic device 101 is exposed to the corrosive gas is M1 is the resistance value R of the resistive film 2 R Therefore, before the environmental diagnostic device 101 is exposed to the corrosive gas, the current mainly flows through the thin metal film 4.

[0030] As the corrosion of the metal thin film 4 by the corrosive gas progresses, the resistance value of the metal thin film 4 decreases from the initial resistance value R M This is because a part of the metal thin film 4 becomes a corrosion product or is lost. The resistance value R of the metal thin film 4 after the metal thin film 4 located between the pair of electrodes 1 is broken M2 is the initial resistance value R of the metal thin film 4 M1 On the other hand, since the resistive film 2 covered by the protective film 3 is not exposed to the corrosive gas, the resistance value R R The resistance value R of the metal thin film 4 does not change. M 2 is the resistance value R R For example, the resistance value R R Therefore, the resistance value R of the metal thin film 4 M2 is the resistance value R of the resistive film 2 R Therefore, the combined resistance R of the resistive film 2 and the metal thin film 4 after the metal thin film 4 is broken can be considered to be infinite. C2 is R R Equivalent to (R C2 ≒R R ) can be considered as

[0031] In this way, the combined resistance value of the resistive film 2 and the thin metal film 4 is significantly different before and after at least the thin metal film 4 is broken. 12 By detecting this, it is possible to detect that the metal thin film 4 has been broken.

[0032] The effects of the environmental diagnostic sensor 11 and the environmental diagnostic device 101 will be described below in comparison with a comparative example. In the environmental diagnostic sensor according to the comparative example, the metal thin film does not have the first portion 41 and is electrically connected in series to the resistive film. In this comparative example, the metal thin film and the resistive film each require their own dedicated areas, making it difficult to reduce the size.

[0033] In contrast, the environmental diagnostic sensor 11 has the first portion 41 in which the thin metal film 4 is disposed on the resistive film 2 via the protective film 3, and therefore can be made smaller than the comparative example.

[0034] Furthermore, in the comparative example, a verification test is required at the time of design to ensure that the resistive film does not corrode and break before the thin metal film does.

[0035] In contrast, in the environment diagnostic sensor 11, the resistive film 2 is covered with the protective film 3 and the thin metal film 4, so that the thin metal film 4 inevitably corrodes and breaks before the resistive film 2, preventing the resistive film 2 from corroding and breaking before the thin metal film 4. Therefore, the above-mentioned verification test is unnecessary in the environment diagnostic sensor 11. Therefore, the manufacturing costs of the environment diagnostic sensor 11 and the environment diagnostic device 101 can be reduced compared to the comparative example.

[0036] <Modifications> The protective film 3 need only be disposed between at least the resistive film 2 and the first portion 41 of the thin metal film 4, and need not cover the resistive film 2. The resistive film 2 may have a surface exposed from the protective film 3 and exposed to the corrosive gas. Such a resistive film 2 may be made of a material that is more resistant to the corrosive gas than the thin metal film 4. Such an environmental diagnostic sensor can also be made smaller than the comparative example.

[0037] 5 and 6, unless otherwise specified, an environmental diagnosis device 102 according to embodiment 2 has the same configuration and effects as those of embodiment 1. Therefore, the same components as those of embodiment 1 are denoted by the same reference numerals, and description thereof will not be repeated.

[0038] As shown in FIGS. 5 and 6, the environment diagnostic device 102 according to the second embodiment includes an environment diagnostic sensor array 12 including a plurality of environment diagnostic sensors.

[0039] The environmental diagnostic sensor array 12 includes a first environmental diagnostic sensor 11A and a second environmental diagnostic sensor 11B. Each of the first environmental diagnostic sensor 11A and the second environmental diagnostic sensor 11B has the same configuration and functions and effects as the environmental diagnostic sensor 11 in the first embodiment.

[0040] 5 and 6, the first environmental diagnostic sensor 11A is electrically connected in series with the second environmental diagnostic sensor 11B. The resistive film 2 and the thin metal film 4 of the first environmental diagnostic sensor 11A are electrically connected in series with the resistive film 2 and the thin metal film 4 of the second environmental diagnostic sensor 11B.

[0041] As shown in Fig. 6, the initial film thickness TB of the metal thin film 4B of the second environmental diagnostic sensor 11B before exposure to a corrosive gas is thicker than the initial film thickness TA of the metal thin film 4A of the first environmental diagnostic sensor 11A before exposure to a corrosive gas. The material constituting the metal thin film 4B of the second environmental diagnostic sensor 11B is the same as the material constituting the metal thin film 4A of the first environmental diagnostic sensor 11A. The first environmental diagnostic sensor 11A and the second environmental diagnostic sensor 11B differ only in the initial film thickness of the metal thin film. The initial resistance value of the metal thin film 4 of the second environmental diagnostic sensor 11B before exposure to a corrosive gas is smaller than the initial resistance value of the metal thin film 4 of the first environmental diagnostic sensor 11A before exposure to a corrosive gas.

[0042] In the first environmental diagnostic sensor 11A, the initial resistance of the metal thin film 4A before exposure to a corrosive gas is smaller than the resistance of the resistive film 2A. In the second environmental diagnostic sensor 11B, the initial resistance of the metal thin film 4B before exposure to a corrosive gas is smaller than the resistance of the resistive film 2B. The resistance of the resistive film 2A is, for example, the same as the resistance of the resistive film 2B. The film thickness of the resistive film 2A is, for example, the same as the film thickness of the resistive film 2B. The material constituting the resistive film 2A is, for example, the same as the material constituting the resistive film 2B. In other words, in the second environmental diagnostic sensor 11B, the initial resistance of the metal thin film 4 before exposure to a corrosive gas is significantly smaller than the resistance of the resistive film 2B.

[0043] One of the pair of electrodes 1 of the first environmental diagnostic sensor 11A is electrically connected in series with one of the pair of electrodes 1 of the second environmental diagnostic sensor 11B via wiring 62. The first environmental diagnostic sensor 11A and the second environmental diagnostic sensor 11B are mounted on, for example, a circuit board 60. The pair of electrodes 1 of each of the first environmental diagnostic sensor 11A and the second environmental diagnostic sensor 11B are mounted on and electrically connected to the circuit board 60 by a bonding member 63. The bonding member 63 is, for example, solder.

[0044] The wiring 62 is formed as a wiring pattern on the substrate 61 of the circuit board 60, for example. The wiring 62 extends, for example, along the first direction DR1. The first environmental diagnostic sensor 11A and the second environmental diagnostic sensor 11B are arranged, for example, side by side at a distance from each other in the first direction DR1. The material constituting the wiring 62 includes, for example, aluminum (Al).

[0045] The wiring 62 may have any shape in plan view. The relative positional relationship between the first environmental diagnostic sensor 11A and the second environmental diagnostic sensor 11B in plan view may be set arbitrarily. The material forming the wiring 62 may include stainless steel.

[0046] The upper surface of the thin metal film 4B of the second environmental diagnostic sensor 11B protrudes higher than the upper surface of the thin metal film 4A of the first environmental diagnostic sensor 11A. The upper surface of the thin metal film 4B of the second environmental diagnostic sensor 11B may be disposed flush with the upper surface of the thin metal film 4A of the first environmental diagnostic sensor 11A. In this case, it is sufficient that the upper surface of the wiring pattern in the area on the circuit board 60 where the second environmental diagnostic sensor 11B is mounted is recessed relative to the upper surface of the wiring pattern in the area where the first environmental diagnostic sensor 11A is mounted.

[0047] As shown in FIG. 7 , in the environmental diagnostic device 102, the combined resistance of the environmental diagnostic sensor array 12 changes as the corrosion of the metal thin films 4A and 4B progresses. Because the initial thickness TA of the metal thin film 4A of the first environmental diagnostic sensor 11A is thinner than the initial thickness TB of the metal thin film 4B of the second environmental diagnostic sensor 11B, the metal thin film 4A breaks due to corrosion before the metal thin film 4B does. When the metal thin film 4A breaks, the combined resistance of the resistive film 2 and the metal thin film 4A in the first environmental diagnostic sensor 11A changes significantly, and the combined resistance of the environmental diagnostic sensor array 12 also changes similarly. When the metal thin film 4B breaks, the combined resistance of the resistive film 2 and the metal thin film 4B in the second environmental diagnostic sensor 11B also changes significantly, and the combined resistance of the environmental diagnostic sensor array 12 also changes similarly. The amount of change R in the combined resistance of the resistive film 2 and the metal thin film 4B in the second environmental diagnostic sensor 11B is Bis the change in the combined resistance value R of the resistive film 2 and the thin metal film 4A in the first environmental diagnostic sensor 11A. A Therefore, according to the environmental diagnostic device 102, the change amount R of the combined resistance value of the environmental diagnostic sensor array 12 is A By detecting the disconnection of the metal thin film 4A, the change amount R of the combined resistance value of the environmental diagnostic sensor array 12 is detected. B By detecting these, it is possible to detect breakage of the thin metal film 4B.

[0048] 8, unless otherwise specified, an environmental diagnosis device 103 according to embodiment 3 has the same configuration and effects as those of embodiment 2. Therefore, the same components as those of embodiment 2 are denoted by the same reference numerals, and description thereof will not be repeated.

[0049] 8, the environmental diagnostic device 103 according to the third embodiment includes an environmental diagnostic sensor array 13. The environmental diagnostic sensor array 13 includes a third environmental diagnostic sensor 11C and a fourth environmental diagnostic sensor 11D. Each of the third environmental diagnostic sensor 11C and the fourth environmental diagnostic sensor 11D has the same configuration and functions and effects as the environmental diagnostic sensor 11 according to the first embodiment.

[0050] 8, the third environmental diagnostic sensor 11C is electrically connected in series with the fourth environmental diagnostic sensor 11D, and the resistive film 2C and thin metal film 4C of the third environmental diagnostic sensor 11C are electrically connected in series with the resistive film 2D and thin metal film 4D of the fourth environmental diagnostic sensor 11D.

[0051] The material constituting the thin metal film 4D of the fourth environmental diagnostic sensor 11D is different from the material constituting the thin metal film 4C of the third environmental diagnostic sensor 11C. The material constituting the thin metal film 4C is more susceptible to corrosion by the corrosive gas X than, for example, the material constituting the thin metal film 4D. The material constituting the thin metal film 4D is more susceptible to corrosion by the corrosive gas Y, which is different from the corrosive gas X, than, for example, the material constituting the thin metal film 4C.

[0052] The initial thickness TC of the thin metal film 4C of the third environmental diagnostic sensor 11C is the same as the initial thickness TD of the thin metal film 4D of the fourth environmental diagnostic sensor 11D. The only difference between the third environmental diagnostic sensor 11C and the fourth environmental diagnostic sensor 11D is the material of the thin metal film 4. In the environmental diagnostic sensor array 13, the initial resistance value of the thin metal film 4D of the fourth environmental diagnostic sensor 11D before exposure to the corrosive gas is set to be smaller than the initial resistance value of the thin metal film 4C of the third environmental diagnostic sensor 11C before exposure to the corrosive gas. Furthermore, the change R of the combined resistance value of the third environmental diagnostic sensor 11C before and after the thin metal film 4C is broken due to corrosion is C is the change R of the combined resistance value of the fourth environment diagnostic sensor 11D before and after the metal thin film 4D is broken due to corrosion. D is set smaller than

[0053] 9 and 10 , in the environment diagnostic device 102, the combined resistance value of the environment diagnostic sensor array 12 changes as the corrosion of the metal thin films 4C and 4D progresses. The combined resistance value of the environment diagnostic sensor array 12 changes in two ways depending on the corrosive gas contained in the installation environment of the environment diagnostic device 103.

[0054] 9 , in an environment X containing a corrosive gas X, the metal thin film 4C is more susceptible to corrosion by the corrosive gas X than the metal thin film 4D, and therefore the metal thin film 4C corrodes and breaks before the metal thin film 4D does. When the metal thin film 4C breaks, the combined resistance of the resistive film 2C and the metal thin film 4C in the third environment diagnostic sensor 11C changes significantly, and the combined resistance of the environmental diagnostic sensor array 13 also changes in a similar manner. Thereafter, when the metal thin film 4D breaks in the environment X, the combined resistance of the resistive film 2D and the metal thin film 4D in the fourth environment diagnostic sensor 11D changes significantly, and the combined resistance of the environmental diagnostic sensor array 13 also changes in a similar manner.

[0055] 10 , in environment Y containing corrosive gas Y, metal thin film 4D is more susceptible to corrosion by corrosive gas Y than metal thin film 4C, and therefore metal thin film 4D corrodes and breaks before metal thin film 4C. When metal thin film 4D breaks, the combined resistance of resistive film 2D and metal thin film 4D in fourth environment diagnostic sensor 11D changes significantly, and the combined resistance of environmental diagnostic sensor array 13 also changes in a similar manner. Thereafter, when metal thin film 4C breaks in environment X, the combined resistance of resistive film 2C and metal thin film 4C in third environment diagnostic sensor 11C also changes significantly, and the combined resistance of environmental diagnostic sensor array 13 also changes in a similar manner.

[0056] The change R in the combined resistance value of the third environment diagnostic sensor 11C before and after the metal thin film 4C is broken due to corrosion C is the change R of the combined resistance value of the fourth environment diagnostic sensor 11D before and after the metal thin film 4D is broken due to corrosion. D Therefore, according to the environmental diagnostic device 103, the change amount R of the combined resistance value of the environmental diagnostic sensor array 13 is C By detecting the disconnection of the metal thin film 4C, the change amount R of the combined resistance value of the environmental diagnostic sensor array 13 is detected. D Furthermore, when the initial change in the combined resistance of the environmental diagnostic sensor array 13 is equal to or greater than the change R C If so, the installation environment is environment X, and the change amount R D If so, it can be detected that the installation environment is environment Y.

[0057] 11, unless otherwise specified, an environmental diagnosis device 104 according to embodiment 4 has the same configuration and effects as those of embodiment 2. Therefore, the same components as those of embodiment 2 are denoted by the same reference numerals, and description thereof will not be repeated.

[0058] 11 , the environment diagnostic device 104 according to the fourth embodiment includes an environment diagnostic sensor array 14. The environment diagnostic sensor array 14 includes a fifth environment diagnostic sensor 11E, a sixth environment diagnostic sensor 11F, a seventh environment diagnostic sensor 11G, and an eighth environment diagnostic sensor 11H. The fifth environment diagnostic sensor 11E, the sixth environment diagnostic sensor 11F, the seventh environment diagnostic sensor 11G, and the eighth environment diagnostic sensor 11H have the same configurations and functions and effects as the environment diagnostic sensor 11 according to the first embodiment.

[0059] As shown in FIG. 11, the fifth environment diagnostic sensor 11E, the sixth environment diagnostic sensor 11F, the seventh environment diagnostic sensor 11G, and the eighth environment diagnostic sensor 11H are electrically connected in series with one another.

[0060] 11 , the initial film thickness TF of the thin metal film 4F of the sixth environmental diagnostic sensor 11F before exposure to a corrosive gas is thicker than the initial film thickness TE of the thin metal film 4E of the fifth environmental diagnostic sensor 11E before exposure to a corrosive gas. The material constituting the thin metal film 4F of the sixth environmental diagnostic sensor 11F is the same as the material constituting the thin metal film 4E of the fifth environmental diagnostic sensor 11E. The fifth environmental diagnostic sensor 11E and the sixth environmental diagnostic sensor 11F differ only in the initial film thickness of the thin metal film. The initial resistance value of the thin metal film 4F of the sixth environmental diagnostic sensor 11F before exposure to a corrosive gas is smaller than the initial resistance value of the thin metal film 4E of the fifth environmental diagnostic sensor 11E before exposure to a corrosive gas.

[0061] The initial film thickness TH of the thin metal film 4H of the eighth environment diagnostic sensor 11H before exposure to a corrosive gas is thicker than the initial film thickness TG of the thin metal film 4G of the seventh environment diagnostic sensor 11G before exposure to a corrosive gas. The material constituting the thin metal film 4H of the eighth environment diagnostic sensor 11H is the same as the material constituting the thin metal film 4G of the seventh environment diagnostic sensor 11G. The seventh environment diagnostic sensor 11G and the eighth environment diagnostic sensor 11H differ only in the initial film thickness of the thin metal film. The initial resistance value of the thin metal film 4H of the eighth environment diagnostic sensor 11H before exposure to a corrosive gas is smaller than the initial resistance value of the thin metal film 4G of the seventh environment diagnostic sensor 11G before exposure to a corrosive gas.

[0062] The materials constituting the thin metal film 4G of the seventh environmental diagnostic sensor 11G and the thin metal film 4H of the eighth environmental diagnostic sensor 11H are different from the materials constituting the thin metal film 4E of the fifth environmental diagnostic sensor 11E and the thin metal film 4F of the sixth environmental diagnostic sensor 11F. The materials constituting the thin metal films 4E and 4F are more susceptible to corrosion by the corrosive gas X than, for example, the materials constituting the thin metal films 4G and 4H. The materials constituting the thin metal films 4G and 4H are more susceptible to corrosion by the corrosive gas Y than, for example, the materials constituting the thin metal films 4E and 4F.

[0063] The change R in the combined resistance value of the fifth environment diagnostic sensor 11E before and after the metal thin film 4E is broken due to corrosion E is the change R of the combined resistance value of the sixth environment diagnostic sensor 11F before and after the metal thin film 4F is broken due to corrosion. F The change amount R of the combined resistance value of the seventh environment diagnostic sensor 11G before and after the metal thin film 4G is broken due to corrosion is set to be smaller than G is the change R of the combined resistance value of the eighth environment diagnostic sensor 11H before and after the metal thin film 4H is broken due to corrosion. H The change amount R of the combined resistance of the sixth environment diagnostic sensor 11F is set to be smaller than the F is the change amount R of the combined resistance value of the seventh environmental diagnosis sensor 11G. G is set smaller than

[0064] 12 and 13, in the environment diagnostic device 104, the combined resistance value of the environment diagnostic sensor array 14 changes as the corrosion of the metal thin films 4E, 4F, 4G, and 4H progresses. Similar to the combined resistance value of the environment diagnostic sensor array 13 in the third embodiment, the combined resistance value of the environment diagnostic sensor array 14 also changes in two ways depending on the corrosive gas contained in the installation environment of the environment diagnostic device 104.

[0065] 12 , in an environment X containing a corrosive gas X, the metal thin films 4E and 4F are more susceptible to corrosion by the corrosive gas X than the metal thin films 4G and 4H, the metal thin film 4E is more susceptible to corrosion by the corrosive gas X than the metal thin film 4F, and the metal thin film 4G is more susceptible to corrosion by the corrosive gas X than the metal thin film 4H. Therefore, breaks due to corrosion occur in the order of the metal thin film 4E, the metal thin film 4F, the metal thin film 4G, and the metal thin film 4H.

[0066] As shown in Figure 13, in an environment Y containing corrosive gas Y, metal thin film 4G and metal thin film 4H are more susceptible to corrosion by corrosive gas Y than metal thin film 4E and metal thin film 4F, metal thin film 4G is more susceptible to corrosion by corrosive gas Y than metal thin film 4H, and metal thin film 4E is more susceptible to corrosion by corrosive gas Y than metal thin film 4F, so that breaks due to corrosion occur in the order of metal thin film 4G, metal thin film 4H, metal thin film 4E, and metal thin film 4F.

[0067] When each metal thin film is broken, the combined resistance value of the environmental diagnostic sensor including the broken metal thin film changes, and the combined resistance value of the environmental diagnostic sensor array 14 also changes in the same way. The amount of change R in the combined resistance value of the fifth environmental diagnostic sensor 11E before and after the metal thin film 4E is broken due to corrosion is E is the change R of the combined resistance value of the sixth environment diagnostic sensor 11F before and after the metal thin film 4F is broken due to corrosion. F The change amount R of the combined resistance value of the seventh environment diagnostic sensor 11G before and after the metal thin film 4G is broken due to corrosion is smaller than G is the change R of the combined resistance value of the eighth environment diagnostic sensor 11H before and after the metal thin film 4H is broken due to corrosion. H The change in the combined resistance value of the sixth environment diagnostic sensor 11F is smaller than F is the change amount R of the combined resistance value of the seventh environmental diagnosis sensor 11G. G Therefore, according to the environment diagnostic device 104, the amount of change in the combined resistance value of the environment diagnostic sensor array 14 is smaller than the amount of change R E ~R H By detecting which of the thin metal films 4E to 4H is broken, it is possible to detect a break in any of the thin metal films 4E to 4H. EIf so, the installation environment is environment X, and the change amount R G If so, it can be detected that the installation environment is environment Y.

[0068] 14, unless otherwise specified, an environmental diagnosis device 105 according to embodiment 5 has the same configuration and effects as those of embodiment 2. Therefore, the same components as those of embodiment 2 are denoted by the same reference numerals, and description thereof will not be repeated.

[0069] 14 , an environmental diagnostic device 105 according to the fifth embodiment includes an environmental diagnostic sensor array 12, a circuit board 60 serving as a holder, and a plurality of fixing members 50. Each of the first and second environmental diagnostic sensors 11A and 11B included in the environmental diagnostic sensor array 12 is individually and detachably fixed to the circuit board 60 by the fixing members 50. The environmental diagnostic device 105 differs from the environmental diagnostic device 102 in that each of the first and second environmental diagnostic sensors 11A and 11B is individually and detachably fixed to the circuit board 60 by the fixing members 50, rather than by a joining member 63 (see FIG. 5 ). The circuit board 60 has a structure for engaging with the fixing members 50.

[0070] Preferably, the fixing member 50 electrically connects each of the first environmental diagnostic sensor 11A and the second environmental diagnostic sensor 11B to the wiring pattern of the circuit board 60 .

[0071] The fixing member 50 includes, for example, a first connecting portion 51, a second connecting portion 52, a third connecting portion 53, and a fourth connecting portion 54. The first connecting portion 51, the second connecting portion 52, the third connecting portion 53, and the fourth connecting portion 54 are connected to each other in this order. The first connecting portion 51 is connected to the thin metal film 4 of each of the first environmental diagnostic sensor 11A and the second environmental diagnostic sensor 11B. The first connecting portion 51 has, for example, a lower surface that contacts the upper surface of the thin metal film 4. The second connecting portion 52 is connected to one of the pair of electrodes 1 of each of the first environmental diagnostic sensor 11A and the second environmental diagnostic sensor 11B. The second connecting portion 52 has, for example, a side surface that contacts one of the side surfaces of the pair of electrodes 1. The third connecting portion 53 is connected to the wiring pattern of the circuit board 60. The fourth connecting portion 54 is connected to the substrate 61 of the circuit board 60. The third connecting portion 53 and the fourth connecting portion 54 are configured to detachably engage with the circuit board 60.

[0072] The fixing member 50 includes, for example, a screw. The first connecting portion 51 may be configured as a head portion of the screw. The second connecting portion 52 may be configured as a shank portion of the screw. The third connecting portion 53 and the fourth connecting portion 54 may be configured as threaded portions of the screws. In this case, the substrate 61 and the wiring pattern of the circuit board 60 each have a screw hole that screws into the screw portion.

[0073] The fixing member 50 does not necessarily have to have the fourth connecting portion 54. Screw holes may be provided only in the wiring pattern of the circuit board 60.

[0074] In the environmental diagnostic device 105, the first environmental diagnostic sensor 11A and the second environmental diagnostic sensor 11B can be individually attached to and detached from the circuit board 60. This eliminates the need to fix the first environmental diagnostic sensor 11A and the second environmental diagnostic sensor 11B to the circuit board 60 at any time during the manufacture of the circuit board 60. In other words, the first environmental diagnostic sensor 11A and the second environmental diagnostic sensor 11B can be attached to the circuit board 60 later. Furthermore, the first environmental diagnostic sensor 11A and the second environmental diagnostic sensor 11B can be individually replaced at any time without replacing the circuit board 60. Therefore, with the environmental diagnostic device 105, for example, after the metal thin film 4A is broken, the first environmental diagnostic sensor 11A can be replaced with a new first environmental diagnostic sensor 11A, allowing repeated environmental diagnosis.

[0075] 16 and 17, unless otherwise specified, an environmental diagnosis device 106 according to embodiment 6 has the same configuration and effects as those of embodiment 1. Therefore, the same components as those of embodiment 1 are denoted by the same reference numerals, and description thereof will not be repeated.

[0076] The environmental diagnostic device 106 includes an environmental diagnostic sensor 11I. In the environmental diagnostic sensor 11I, a thin metal film 4 is disposed on at least one of a pair of side surfaces of the environmental diagnostic sensor 11I facing opposite each other in the second direction DR2. The environmental diagnostic sensor 11I includes, for example, a plurality of thin metal films 4 disposed on each of the pair of side surfaces of the environmental diagnostic sensor 11I. Note that the thin metal film 4 may be disposed on only one of the pair of side surfaces of the environmental diagnostic sensor 11I. In the environmental diagnostic sensor 11I, the upper surface of the protective film 3 is exposed.

[0077] The metal thin film 4 is disposed at a distance from the resistive film 2 in the second direction DR2. The metal thin film 4 is separated from the resistive film 2 in the second direction DR2 by the protective film 3. The metal thin film 4 has, for example, a first portion 43 (see FIG. 17 ) disposed so as to overlap the resistive film 2 in the second direction DR2, and a pair of second portions 44 disposed so as to overlap each of the pair of electrodes 1 in the second direction DR2. The first portion 43 is continuous with the pair of second portions 44.

[0078] The metal thin film 4 further has, for example, a third portion disposed on a third side surface or a fourth side surface of the insulating substrate 5 in the second direction DR2. Note that the metal thin film 4 does not necessarily have to have the third portion.

[0079] The environment diagnostic sensor 11I in the sixth embodiment can be included in each of the environment diagnostic sensor arrays 12, 13, and 14 in the second to fifth embodiments.

[0080] 18, unless otherwise specified, an environmental diagnosis device 107 according to embodiment 7 has the same configuration and effects as those of embodiment 1. Therefore, the same components as those of embodiment 1 are denoted by the same reference numerals, and description thereof will not be repeated.

[0081] The environmental diagnostic device 107 includes an environmental diagnostic sensor 11J. In the environmental diagnostic sensor 11J, a metal thin film 4 is disposed on the lower surface of an insulating substrate 5. The metal thin film 4 electrically connects the other ends of a pair of electrodes 1 disposed on the lower surface of the insulating substrate 5. The metal thin film 4 has a fourth portion 45 disposed so as to overlap the resistive film 2 in a direction perpendicular to the lower surface of the insulating substrate 5, and a pair of second portions 46 disposed so as to overlap each of the pair of electrodes 1 in the perpendicular direction.

[0082] The environment diagnostic sensor 11J in the seventh embodiment can be included in each of the environment diagnostic sensor arrays 12, 13, and 14 in the second to fifth embodiments.

[0083] <Example of Setting the Metal Thin Film Thickness> In the environmental diagnosis devices 101 to 107 according to embodiments 1 to 7, the thickness of the metal thin film 4 can be set based on the expected degree of corrosion progression of the electrical equipment in the usage environment or the expected corrosion defect thickness after a predetermined time has elapsed based on the corrosiveness of the usage environment of the electrical equipment, as described above. FIG. 19 is a graph showing the rate of change over time (corrosion rate) of the corrosion defect thickness (amount of corrosion) of the metal thin film depending on the environment. As shown in FIG. 19, the corrosion rate of the metal thin film 4 exposed to a corrosive gas varies depending on the installation environment of the environmental diagnosis device. Corrosion levels 1 and 2 in FIG. 19 indicate the degree of corrosion rate of the metal thin film 4 depending on the installation environment. An environment of corrosion level 2 is more likely to corrode the metal thin film 4 than an environment of corrosion level 1. Environment 1 refers to an environment in which the corrosion rate of the metal thin film 4 is expected to be slower than the corrosion rate at corrosion level 1. Environment 2 refers to an environment in which the corrosion rate of the metal thin film 4 is expected to be slower than the corrosion rate at corrosion level 2. Environment 3 refers to an environment in which the corrosion rate of the thin metal film 4 is expected to be faster than the corrosion rate at corrosion level 2.

[0084] The thickness of the metal thin film 4 may be set based on the amount of corrosion expected after a predetermined time has elapsed. For example, the thickness of the metal thin film 4 may be set to a thickness equivalent to the amount of corrosion expected after a predetermined time has elapsed. Furthermore, for example, if the environment in which the environmental diagnosis device 102 is installed is assumed to be environment 2, the thickness TA of the metal thin film 4A may be set to be equal to the amount of corrosion expected after a predetermined time has elapsed at corrosion level 1. The thickness TB of the metal thin film 4B may be set to be equal to the amount of corrosion expected after a predetermined time has elapsed at corrosion level 2. In this way, if a break in the metal thin film 4A is detected but a break in the metal thin film 4B is not detected after the predetermined time has elapsed, it can be assumed that the installation environment of the environmental diagnosis device 102 is environment 2.

[0085] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0086] 1 Electrode, 2 Resistive film, 2, 2A, 2B, 2C, 2D Resistive film, 3 Protective film, 4, 4A, 4B, 4C, 4D, 4E, 4F, 4G, 4H Metal thin film, 5 Insulating substrate, 6 Internal electrode, 7 Intermediate electrode, 8 External electrode, 10 Fixed resistor, 11, 11I, 11J Environmental diagnostic sensor, 11A First environmental diagnostic sensor, 11B Second environmental diagnostic sensor, 11C Third environmental diagnostic sensor, 11D Fourth environmental diagnostic sensor, 11E Fifth environmental diagnostic sensor, 11F Sixth environmental diagnostic sensor, 11G Seventh environmental diagnostic sensor, 11H Eighth environmental diagnostic sensor, 12, 13, 14 Environmental diagnostic sensor array, 20 Power supply, 30 Resistance measuring device, 31 Central portion, 32 Outer edge portion, 40 Analysis device, 41, 43 First portion, 42, 44 Second portion, 50 Fixing member, 51 First connection portion, 52 Second connection portion, 53 Third connection portion, 54 Fourth connection portion, 60 Circuit board, 61 Board, 62 Wiring, 63 Joint member, 101, 102, 103, 104, 105 Environmental diagnosis device, 301 Voltmeter, 302 Ammeter.

Claims

1. An environmental diagnostic sensor comprising: a pair of electrodes; a resistive film connecting the pair of electrodes; a protective film disposed on the resistive film; and a thin metal film exposed to a corrosive gas, wherein the resistive film and the thin metal film are electrically connected in parallel to each other between the pair of electrodes.

2. The environmental diagnostic sensor according to claim 1, wherein the thin metal film has a first portion disposed on the resistive film via the protective film.

3. The environmental diagnostic sensor according to claim 1, further comprising an insulating substrate having a first surface and a second surface located opposite the first surface, wherein each of the pair of electrodes has one end located on the first surface of the insulating substrate and the other end located on the second surface, wherein the resistive film and the protective film are located on the first surface, and wherein the thin metal film is located on the second surface.

4. The environmental diagnostic sensor according to any one of claims 1 to 3, wherein the protective film covers the resistive film.

5. The environmental diagnostic sensor according to any one of claims 1 to 4, wherein the initial resistance value of the thin metal film before exposure to the corrosive gas is smaller than the resistance value of the resistive film.

6. The environment diagnostic sensor according to claim 5, wherein the resistance value of the metal thin film after exposure to the corrosive gas is greater than the initial resistance value of the metal thin film.

7. The environmental diagnostic sensor according to any one of claims 1 to 6, wherein the thin metal film covers the protective film.

8. An environmental diagnostic device comprising: an environmental diagnostic sensor according to any one of claims 1 to 7; a measuring device that measures the combined resistance of the resistive film and the metal thin film; and an analyzing device that identifies at least one of the type of corrosive gas and the degree of corrosion of the metal thin film based on the amount of change in the combined resistance.

9. An environmental diagnostic sensor array comprising a plurality of environmental diagnostic sensors, each of which is an environmental diagnostic sensor according to any one of claims 1 to 7, wherein at least one of the initial film thickness of the thin metal film before exposure to the corrosive gas and the material constituting the thin metal film is different among the plurality of environmental diagnostic sensors, and the plurality of environmental diagnostic sensors are electrically connected in series with each other.

10. The environmental diagnostic sensor array according to claim 9, further comprising: a holder that holds the plurality of environmental diagnostic sensors; and a plurality of fixing members that individually and detachably fix each of the plurality of environmental diagnostic sensors to the holder.

11. An environmental diagnostic device further comprising: an environmental diagnostic sensor array according to claim 9 or 10; a measuring device for measuring a combined resistance of the plurality of environmental diagnostic sensors; and an analyzing device for identifying at least one of the type of the corrosive gas and the degree of corrosion of the metal thin film based on the amount of change in the combined resistance.

Images