Sensor element, sensor module, and electronic apparatus

Abstract

This sensor element (101) comprises a pair of electrodes (2) and a resin film (3) that separates the pair of electrodes. The resin film has a surface (30) that connects the pair of electrodes. An additive that bleeds out onto the surface and reduces the resistance value between the pair of electrodes is added to the resin film.

Description

Sensor element, sensor module, and electronic device

[0001] The present disclosure relates to a sensor element, a sensor module, and an electronic device.

[0002] Components (e.g., electronic components) included in electronic devices deteriorate over time in their operating environment, leading to damage. Therefore, such components generally have a protective film, such as a sealant, as a structure to suppress the progression of deterioration in the expected operating environment.

[0003] However, if the customer (user) uses the electronic device in a harsher environment than the manufacturer intended, the deterioration may progress more quickly than the manufacturer anticipated, and the electronic device may be damaged earlier than expected. When electronic devices are damaged earlier than expected, an investigation is conducted to determine the cause, but in some cases the cause cannot be determined because the usage environment cannot be accurately identified. Therefore, a technology has been proposed to estimate the usage environment of electronic devices.

[0004] The sulfide detection sensor described in Japanese Patent Laid-Open No. 2021-181931 (Patent Document 1) is a sensor for detecting the cumulative amount of sulfide due to sulfide gas contained in the usage environment.

[0005] Japanese Patent Application Laid-Open No. 2021-181931

[0006] However, no technology has yet been found that can estimate the cumulative load applied to the components of an electronic device due to the temperature and humidity of the environment in which the electronic device is used.

[0007] An object of the present disclosure is to provide a technology capable of estimating the cumulative load applied to components of an electronic device due to the temperature and humidity of the environment in which the electronic device is used.

[0008] The sensor element according to the present disclosure includes a pair of electrodes and a resin film separating the pair of electrodes. The resin film has a surface connecting the pair of electrodes. An additive is added to the resin film, which bleeds out to the surface to reduce the resistance between the pair of electrodes.

[0009] According to the present disclosure, it is possible to estimate the cumulative load applied to components of an electronic device depending on the temperature and humidity of the environment in which the electronic device is used.

[0010] 6 is a cross-sectional view showing a state before the start of use of an example of a sensor element according to embodiment 1. FIG. 7 is a plan view of the sensor element shown in FIG. 1. FIG. 7 is a cross-sectional view showing a state after the start of use of the sensor element shown in FIG. 1, in which it is determined that a pair of electrodes has been short-circuited. FIG. 8 is a graph showing an example of a change in resistance value over time between a pair of electrodes in a specific usage environment for the sensor element according to embodiment 1. FIG. 9 is a graph showing an example of measurement results of the time until a pair of electrodes is short-circuited (short-circuit time) under a plurality of temperature and humidity conditions for the sensor element according to embodiment 1. FIG. 9 is a plan view showing an example of a sensor module according to embodiment 2. FIG. 10 is a partial enlarged plan view of region VII in FIG. 6. FIG. 11 is a cross-sectional view showing an example of a sensor module according to embodiment 2. FIG. 12 is a diagram showing an example of an electronic device according to embodiment 3. FIG. 13 is a diagram showing a specific example of an electronic device according to embodiment 3. FIG. 14 is a diagram showing a modified example of the electronic device according to embodiment 3. FIG. 15 is a graph showing an example of evaluation results of the short-circuit time (lifespan) of each sensor element in a guaranteed environment and the short-circuit time of each sensor element in a usage environment, in an electronic device including a plurality of sensor elements whose short-circuit times of a pair of electrodes differ from one another in a guaranteed environment.

[0011] 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.

[0012] The sensor element according to this embodiment can estimate the temperature and humidity (temperature and humidity) of the environment in which an electronic device is used. When used together with an electronic device main body such as a semiconductor device, the sensor element according to this embodiment can estimate the cumulative value of the load applied to the electronic device main body due to the temperature and humidity (temperature and humidity) of the environment in which the electronic device is used. The electronic device is any electronic device used in a temperature and humidity environment. The electronic device is, for example, an in-vehicle device. The electronic device may be an inverter, a servo motor, a sequencer, or other factory automation device, a railway, an elevator or other lift, a generator, or the like. The sensor element according to this embodiment may be used as part of the electronic device main body or separately from the electronic device.

[0013] 1 and 2 show a state before the start of use of the sensor element 101 (hereinafter also referred to as an initial state). Fig. 3 shows a state after the start of use of the sensor element 101 in which it is determined that a pair of electrodes 2 is short-circuited (hereinafter also referred to as a short-circuit state).

[0014] As shown in FIGS. 1, 2, and 3, the sensor element 101 according to the first embodiment includes an insulating substrate 1, a pair of electrodes 2, a resin film 3, and a protective film 4.

[0015] The insulating substrate 1 has electrical insulation properties. The insulating substrate 1 acts as a support base for supporting the pair of electrodes 2, the resin film 3, and the protective film 4 in the sensor element 101. The insulating substrate 1 is less susceptible to deterioration due to temperature and humidity than the resin film 3. Preferably, the insulating substrate 1 has higher heat resistance and corrosion resistance than the resin film 3. The material constituting the insulating substrate 1 is, for example, aluminum oxide (Al ２ O ３ ), glass (SiO ２ ), and silicon wafer (Si).

[0016] The insulating substrate 1 has, for example, a rectangular parallelepiped shape. The insulating substrate 1 has a first surface (upper surface), a second surface (lower surface), a first side surface, and a second side surface. The first and second surfaces of the insulating substrate 1 extend along a first direction DR1 and a second direction perpendicular to the first direction DR1. The first and second side surfaces face opposite each other in the first direction DR1. The insulating substrate 1 further has a third and fourth side surface. The third and fourth side surfaces each extend between the first and second side surfaces. The third and fourth side surfaces face opposite each other in the second direction.

[0017] Although there are no particular limitations on the dimensions of the insulating substrate 1, it is desirable that the dimensions be as small as possible from the viewpoint of mountability in a sensor module and electronic devices, which will be described later. For example, when the sensor element 101 is mounted on a semiconductor lead frame or a printed circuit board, the dimensions of the insulating substrate 1 may be on the order of several mm to several hundred μm.

[0018] The pair of electrodes 2 are arranged at a distance from each other on the first surface of the insulating substrate 1. Each of the pair of electrodes 2 has a first end 21 arranged on the first surface of the insulating substrate 1 and the other end arranged on the second surface of the insulating substrate 1. The first ends 21 of the pair of electrodes 2 are arranged at a distance from each other on the first surface of the insulating substrate 1. The first ends 21 of the pair of electrodes 2 face each other across a resin film 3. The first ends 21 of the pair of electrodes 2 are covered by a protective film 4. The other ends of the pair of electrodes 2 are arranged at a distance from each other on the second surface of the insulating substrate 1. One of the pair of electrodes 2 covers the first side surface of the insulating substrate 1 and a portion of the first side surface of each of the first and second surfaces. The other of the pair of electrodes 2 covers the second side surface of the insulating substrate 1 and a portion of the second side surface of each of the first and second surfaces. The portion of each of the pair of electrodes 2 that is arranged on the second surface of the insulating substrate 1 functions as a so-called back electrode that is electrically connected to the circuit board (e.g., the circuit board of the main body of the electrical device) on which the sensor element 101 is mounted.

[0019] Each of the pair of electrodes 2 includes, for example, an internal electrode 6 and an external electrode 7. The internal electrode 6 and the external electrode 7 are laminated in this order in a direction perpendicular to the surface of the insulating substrate 1.

[0020] The internal electrode 6 has one end 61 disposed on the first surface of the insulating substrate 1 and the other end disposed on the second surface of the insulating substrate 1. One end 61 of the internal electrode 6 constitutes the first end 21 of each of the pair of electrodes 2. The internal electrode 6 has a surface electrode portion 62 disposed on the first surface of the insulating substrate 1 and a side electrode portion 63 disposed on the first side surface or the second side surface of the insulating substrate 1. In each of the pair of electrodes 2, the surface electrode portion 62 is electrically connected to the side electrode portion 63. Preferably, the surface electrode portion 62 is connected to the side electrode portion 63 so as to have the same potential as the side electrode portion 63.

[0021] The external electrode 7 has one end 71 disposed on the first surface of the insulating substrate 1 and the other end disposed on the second surface of the insulating substrate 1. The one end 71 of the external electrode 7 is disposed, for example, on the surface electrode portion 62 of the internal electrode 6. The one end 71 of the external electrode 7 may also be disposed on the one end 61 of the internal electrode 6. The one end 61 of the internal electrode 6 and the one end 71 of the external electrode 7 may form the first end 21 of each of the pair of electrodes 2. The end face of the one end 71 of the external electrode 7 may be disposed on the same plane as the end face of the one end 61 of the internal electrode 6.

[0022] The internal electrode 6 is covered, for example, on the first surface of the insulating substrate 1 by the resin film 3, the protective film 4, and the external electrode 7. The internal electrode 6 is covered on the second surface, the first side surface, and the second side surface of the insulating substrate 1 by the external electrode 7. The external electrode 7 is exposed on the second surface, the first side surface, and the second side surface of the insulating substrate 1.

[0023] The material constituting the internal electrode 6 includes at least one selected from the group consisting of silver (Ag), nickel (Ni), and chromium (Cr). In the internal electrode 6, the surface electrode portion 62 and the side electrode portion 63 may be made of the same material or different materials. The material constituting the external electrode 7 includes, for example, tin (Sn).

[0024] Each of the pair of electrodes 2 may further have a barrier layer between the internal electrode 6 and the external electrode 7 to suppress interdiffusion. The material constituting the barrier layer includes, for example, nickel (Ni). Each of the internal electrode 6 and the external electrode 7 may be a single conductive film made of a single material, or may be a laminate of multiple conductive films made of different materials.

[0025] The resin film 3 separates the pair of electrodes 2 on the first surface of the insulating substrate 1. The resin film 3 has a surface 30 that connects the pair of electrodes 2 to each other. An additive is added to the resin film 3, which bleeds out onto the surface 30 and reduces the resistance between the pair of electrodes 2. In this specification, "bleed-out" refers to a phenomenon in which an additive added to and mixed inside the resin film 3 precipitates on the surface 30 of the resin film 3 over time in the environment in which the sensor element 101 is used. The additive has the property that the rate of bleed-out changes depending on the temperature and humidity of the environment in which the sensor element 101 is used. The rate of bleed-out of the additive accelerates as the temperature and humidity of the environment in which the sensor element 101 is used increases. The additive that bleeds out onto the surface 30 reduces the resistance between the pair of electrodes 2.

[0026] The resin film 3 is provided so that the additive bleeds out onto the surface 30 to form conductive paths 5 (see FIG. 3 ) that electrically connect the pair of electrodes 2. The conductive paths 5 are formed as the additive bleeds out. The conductive paths 5 are formed by the precipitated components of the additive that bleed out onto the surface 30.

[0027] The material constituting the resin film 3 (the material constituting the base material of the resin film 3) may be any resin material having electrical insulation properties, and includes, for example, at least one of thermoplastic resins such as polyethylene and polybutylene terephthalate, and thermosetting resins such as epoxy.

[0028] There are no particular limitations on the method for forming the resin film 3. The resin film 3 can be formed by injection molding, compression molding, transfer molding, or the like.

[0029] The additive is provided so as to change into an electrolyte by at least one of oxidation and hydration, for example. The additive is provided so as to change into an electrolyte by oxygen or water vapor contained in the atmosphere in the environment in which the sensor element 101 is used, for example. The additive is, for example, an inorganic additive. The additive is, for example, a red phosphorus flame retardant. The additive may be any material that changes the rate of bleed-out depending on the temperature and humidity and can reduce the resistance value between the pair of electrodes 2.

[0030] Preferably, in the initial state, the additive is homogeneously dispersed in the resin film 3. In this specification, "the additive is homogeneously dispersed" means that there is substantially no bias in the distribution of the additive in the initial state. For example, in the initial state, the ratio obtained by dividing the difference in the weight ratio of the additive in any two portions of the resin film 3 aligned in the first direction DR1 by the average value is less than approximately 10%. Preferably, the ratio is less than approximately 5%. More preferably, the ratio is less than approximately 3%. The weight ratio of the additive in any portion of the resin film 3 may be measured using any analytical technique. Examples of such analytical techniques include gas chromatography mass spectrometry and X-ray fluorescence spectrometry (XRF).

[0031] There are no particular limitations on the method for forming the resin film 3 and the additive homogeneously dispersed in the resin film 3. For example, the resin film 3 and the additive homogeneously dispersed in the resin film 3 may be formed by molding a mixed material of the resin material that constitutes the resin film 3 and the additive homogeneously dispersed in the resin material.

[0032] The resin film 3 has, for example, a pair of first portions 31 and a second portion 32. The pair of first portions 31 are disposed on the first ends 21 of the pair of electrodes 2. The second portion 32 connects the pair of first portions 31. The second portion 32 spans between the first ends 21 of the pair of electrodes 2.

[0033] The resin film 3 is in contact with the end face and upper surface of one end 61 of each internal electrode 6 of the pair of electrodes 2, and with the end face of each external electrode 7. The pair of first portions 31 are in contact with the upper surface of one end 61 of each internal electrode 6 of the pair of electrodes 2, and with the end face of each external electrode 7. The second portion 32 is in contact with the end face of one end 61 of each internal electrode 6 of the pair of electrodes 2.

[0034] The protective film 4 covers the surface of the resin film 3. For example, the protective film 4 covers the resin film 3 and each first end 21 of the pair of electrodes 2 connected to the resin film 3. The protective film 4 is disposed, for example, across each external electrode 7 of the pair of electrodes 2. The protective film 4 has electrical insulation properties. The protective film 4 is made of a material different from that of the resin film 3. The protective film 4 suppresses a decrease in the resistance value between the pair of electrodes 2 due to reasons other than bleed-out of additives in the resin film 3. The material constituting the protective film 4 and the thickness of the protective film 4 are set to suppress alteration or deterioration of the resin film 3 due to factors other than temperature and humidity during the time from the initial state to the short-circuit state. The protective film 4 prevents corrosive components and ionic components that corrode the resin film 3 from reaching the resin film 3. The protective film 4 is provided, for example, so as not to form a conductive path on its surface that electrically connects the pair of electrodes 2. The protective film 4 does not contain, for example, additives that bleed out.

[0035] The material constituting the protective film 4 is preferably a material that has excellent mechanical properties and emits little gas (outgas) from the inside to the outside of the protective film 4. The protective film 4 includes, for example, at least one of a polyimide film and a polyamide film.

[0036] As shown in Fig. 1, before the start of use of the sensor element 101, no conductive path is formed that electrically connects the pair of electrodes 2. As shown in Fig. 3, in the sensor element 101, after the start of use, a conductive path 5 that electrically connects the pair of electrodes 2 is formed over time.

[0037] In the sensor element 101, the resistance value between the pair of electrodes 2 gradually decreases from the initial state to the short-circuit state, or decreases gradually and then sharply.

[0038] Fig. 4 is a graph showing an example of the change in resistance between a pair of electrodes 2 over time as the sensor element 101 goes from an initial state to a short-circuit state under a specific environment. Fig. 4 shows the measurement results of the change in resistance between a pair of electrodes 2 over time under an environment of a temperature of 85°C and a relative humidity of 85%, using a sensor element 101 in which the material constituting the resin film 3 contains polyethylene and the additive added to the resin film 3 is a red phosphorus-based flame retardant. The horizontal axis of Fig. 4 represents the test time (unit: hours). The vertical axis of Fig. 4 represents the resistance between the pair of electrodes 2 (unit: Ω).

[0039] In the example shown in Figure 4, the resistance between the pair of electrodes 2 gradually decreased from the initial state to the short-circuit state, and then decreased rapidly. The resistance between the pair of electrodes 2 in the initial state was, for example, several hundred giga-ohms or more. After the test began, the resistance gradually decreased while maintaining a high value of giga-ohms or more, and then decreased rapidly from giga-ohms to mega-ohms or less. In the example shown in Figure 4, it was determined that the pair of electrodes 2 was short-circuited when the resistance between the pair of electrodes 2 decreased to 1 mega-ohm or less.

[0040] The resistance value between the pair of electrodes 2 in the initial state and the resistance value between the pair of electrodes 2 that serves as a criterion for determining whether or not a short circuit has occurred can be set arbitrarily.

[0041] <Method of Using the Sensor Element> The sensor element 101 is used, for example, together with an electronic device in the environment in which the electronic device is used, and is used to estimate the cumulative load applied to the sensor element 101 and the electronic device main body due to the temperature and humidity of the environment. The cumulative load is the cumulative value of the load input to the electronic device main body due to the temperature and humidity.

[0042] In this usage example, correlation data is acquired in advance in an environment having reference temperature and humidity conditions (hereinafter also referred to as the reference environment) between the cumulative load due to temperature and humidity applied to the sensor element 101 and the resistance value between the pair of electrodes 2. The correlation data acquired in advance in the reference environment is, for example, correlation data between the test time and the resistance value between the pair of electrodes 2, as shown in Fig. 4. Hereinafter, the reference resistance value (1 megaΩ in the example shown in Fig. 4) at which it is determined that the pair of electrodes 2 is short-circuited in the reference environment will be referred to as the reference resistance.

[0043] The temperature and humidity conditions of the reference environment are set to be equal to or stricter than the temperature and humidity conditions of the usage environment (hereinafter also referred to as the warranty environment) in which the performance of an electronic device is guaranteed. The reference resistance is set so that the short-circuit time of the sensor element 101 in the warranty environment is equal to or shorter than the warranty period of the electronic device.

[0044] The sensor element 101 is used in the usage environment of the electronic device. The time during which the resistance value between the pair of electrodes 2 in the usage environment of the electronic device falls below the reference resistance is the short-circuit time of the sensor element 101 in the usage environment of the electronic device. If the short-circuit time of the sensor element 101 in the usage environment of the electronic device is shorter than the short-circuit time of the sensor element 101 in the reference environment, it is estimated that at least one of the temperature and humidity of the usage environment of the electronic device is higher than those of the reference environment, and that the cumulative load applied to the sensor element 101 in the usage environment of the electronic device is greater than the cumulative load applied to the sensor element 101 in the reference environment.

[0045] Preferably, the correlation data is acquired in advance in each of a plurality of environments in which at least one of temperature and humidity differs from one another. For example, it is preferable to acquire the correlation data in advance in each of a plurality of environments in which temperature and humidity differ from one another but are constant, using a plurality of sensor elements 101 having the same configuration. In this way, a model that closely matches the correlation data in the plurality of environments acquired in advance can be selected from among general accelerated deterioration models, and based on the selected model and the correlation data in the plurality of environments acquired in advance, it is possible to accurately estimate the short-circuit time until the sensor element 101 reaches the short-circuit state in the environment in which the electronic device is used, or the temperature and humidity of the environment in which the electronic device is used.

[0046] For example, if the additive is transformed into an electrolyte by oxygen or water vapor contained in the atmosphere in which the sensor element 101 is used, the above correlation data obtained in advance under multiple environments using the sensor element 101 closely matches the water vapor pressure model, which is one of the common deterioration acceleration models.

[0047] Fig. 5 is a graph showing an example of a plurality of the above correlation data acquired in advance under a plurality of mutually different temperature and humidity conditions. Fig. 5 shows the measurement results of the change in the resistance value between a pair of electrodes 2 over time under a plurality of mutually different temperature and humidity conditions using a plurality of sensor elements 101 in which the material constituting the resin film 3 contains polyethylene and the additive added to the resin film 3 is a red phosphorus-based flame retardant. The horizontal axis of Fig. 5 shows the partial pressure (unit: Pa) of water vapor in each environment. The vertical axis of Fig. 5 shows the short-circuit time (unit: hours) until the pair of electrodes 2 is short-circuited in each environment. Fig. 5 also shows the above measurement results, as well as the water vapor pressure V based on a water vapor pressure model, which is one of the common temperature and humidity acceleration models. P The relationship between the short circuit time and the temperature, humidity and saturated water vapor pressure is shown. In the water vapor pressure model, the short circuit time is L (unit: hours), the experimental constant is A, and the water vapor pressure calculated from the temperature, humidity and saturated water vapor pressure is V. P (unit: Pa), and the exponent is n, the water vapor pressure is V P The relationship between the short circuit time L and the P -n In the example shown in FIG. 5, the experimental constant A in the water vapor pressure model is 1.97×10 17 and the power exponent n is 3.285. 17 ×V P -3.285 is in good agreement with multiple correlation data previously obtained.

[0048] The water vapor pressure derived above is V P The water vapor pressure, temperature, and humidity of the environment can be estimated from the short-circuit time required for the sensor element 101, which is used together with the electronic device in the usage environment of the electronic device, to reach the short-circuit state, based on the relational expression between the short-circuit time L and the short-circuit time L. For example, if a pair of electrodes 2 of the sensor element 101, which is used together with the electronic device in the usage environment of the electronic device, short-circuits after about five years, it is estimated that the electronic device and the sensor element 101 were used in an environment where the water vapor pressure was about 7000 Pa.

[0049] Alternatively, the water vapor pressure derived as above can be expressed as V PBased on the relational expression between the short circuit time L and the temperature and humidity conditions assumed in the environment in which the electronic device is used, the short circuit time required for the sensor element 101 to reach the short circuit state in the environment in which the electronic device is used can be estimated. For example, if the temperature and relative humidity of the environment in which the electronic device is used are 50°C and 50%, respectively (water vapor pressure V P is assumed to be 61.7 hPa), the short circuit time L is estimated to be about 67,000 hours (about 7.6 years) from the approximation formula shown in FIG.

[0050] <Effects of the Sensor Element> The sensor element 101 includes a pair of electrodes 2 and a resin film 3 separating the pair of electrodes 2. The resin film 3 has a surface 30 connecting the pair of electrodes 2. An additive is added to the resin film 3, which bleeds out onto the surface 30 and reduces the resistance value between the pair of electrodes 2. Therefore, by comparing the correlation data regarding the resistance value between the pair of electrodes 2 obtained by using the sensor element 101 in the usage environment of the electronic device based on the above-mentioned usage method with the correlation data regarding the resistance value between the pair of electrodes 2 obtained in advance in a reference environment having temperature and humidity conditions equivalent to or more severe than the guaranteed environment of the electronic device, it is possible to estimate whether the temperature and humidity of the usage environment of the electronic device are equivalent to the temperature and humidity of the guaranteed environment.

[0051] Preferably, the additive is homogeneously dispersed in the resin film 3. If there is a bias in the distribution of the additive in the resin film 3 in the initial state, there is a risk that the progress of bleed-out of the additive will also be biased, and the short circuit time will vary depending on these biases. If the additive is homogeneously dispersed in the resin film 3, it is possible to prevent the short circuit time from varying depending on the bias in the distribution of the additive.

[0052] Although the model for accelerating deterioration due to temperature and humidity of a semiconductor element sealed with a sealant has not been clearly defined, it is known that the cumulative failure rate of humidity-induced failures of a semiconductor element sealed with a sealant experimentally agrees well with the approximation of the water vapor pressure model. Therefore, the deterioration due to temperature and humidity of the sensor element 101 and the deterioration due to temperature and humidity of a semiconductor element sealed with a sealant can be compared using the same acceleration factor.

[0053] Furthermore, electronic devices are generally subjected to endurance tests under temperature and humidity loads, such as constant temperature and humidity tests and HAST (Highly Accelerated Temperature and Humidity Stress Tests), to calculate acceleration factors and set guaranteed lifespans. The short-circuit time of the pair of electrodes 2 in the sensor element 101 is set, for example, to be shorter than the guaranteed lifespan set for the electronic device. In this way, the pair of electrodes 2 of the sensor element 101 short-circuits before the electronic device is used beyond its guaranteed lifespan and the risk of failure of the electronic device increases. Therefore, the temperature, humidity, and other conditions of the environment in which the electronic device is used can be estimated based on the short-circuit time before the electronic device fails.

[0054] The short-circuit time of the pair of electrodes 2 in the sensor element 101 can be adjusted by the material constituting the resin film 3, the material of the additive thereto, the amount of the additive, etc. For example, if the additive is a phosphorus-based flame retardant, increasing the amount of the additive shortens the short-circuit time, and decreasing the amount of the additive lengthens the short-circuit time.

[0055] In the sensor element 101, the additive may have the property of changing into an electrolyte by at least one of oxidation and hydration. The additive may be an inorganic additive. The additive may be a red phosphorus-based flame retardant. That is, in the sensor element 101, for example, a flame retardant used in sealing materials for semiconductor devices can be used as the additive. The sensor element 101 can achieve the above effects without relying on a special additive.

[0056] In the sensor element 101, the resin film 3 has a pair of first portions 31 disposed on the first ends 21 of the pair of electrodes 2, and a second portion 32 connecting the pair of first portions 31. In this way, even if at least one of the insulating substrate 1, the pair of electrodes 2, and the resin film 3 is deformed, the surface 30 of the resin film 3 can maintain the state in which the pair of electrodes 2 are connected, thereby achieving the above-mentioned effect.

[0057] Preferably, the sensor element 101 further includes a protective film 4 covering the surface 30 of the resin film 3. The protective film 4 has electrical insulating properties and is made of a material different from that of the resin film 3. The sensor element 101 including the protective film 4 can suppress alteration and deterioration of the resin film 3 compared to the sensor element 101 not including the protective film 4. More preferably, the protective film 4 can suppress a decrease in the resistance value between the pair of electrodes 2 due to reasons other than bleed-out of the additive in the resin film 3.

[0058] As described above, the sensor element 101 according to the first embodiment can be used together with an electronic device main body such as a semiconductor element. An example in which the sensor element 101 according to the first embodiment is used together with an electronic device main body such as a semiconductor element will be described below.

[0059] 6, 7, and 8, a sensor module 201 according to a second embodiment has, for example, a small outline package (SOP) structure. The sensor module 201 includes, for example, one sensor element 101, a semiconductor element 20 as an electronic device main body, a sealing body 80, and lead terminals 81.

[0060] The semiconductor element 20 may be any semiconductor element made of any semiconductor material. In the sensor module 201, the short-circuit time of the pair of electrodes 2 in the sensor element 101 is set to be shorter than the guaranteed life of the semiconductor element 20.

[0061] The plurality of lead terminals 81 include a pair of lead terminals 81A, 81B electrically connected to a pair of electrodes 2 of the sensor element 101. The plurality of lead terminals 81 further include a plurality of lead terminals electrically connected to the semiconductor element 20. The plurality of lead terminals 81A, 81B have, for example, lands 82A, 82B. One electrode 2 of the pair of electrodes 2 of the sensor element 101 is disposed on the land 82A and electrically connected to the land 82A via a bonding member 83A. The other electrode 2 of the pair of electrodes 2 is disposed on the land 82B and electrically connected to the land 82B via a bonding member 83B. The bonding member 83 is, for example, solder.

[0062] The sealing body 80 seals the sensor element 101, the semiconductor element 20, a portion of each of the plurality of lead terminals 81 including the lands 82A and 82B, and the bonding members 83A and 83B. The remaining portions of each of the plurality of lead terminals 81 protrude outward beyond the outer peripheral surface of the sealing body 80.

[0063] The package structure of the sensor module 201 is not limited to the SOP structure. The package structure of the sensor module 201 may be, for example, a molded package or a case package. The sensor module 201 may also include a printed circuit board instead of the multiple lead terminals 81. In this case, the sensor element 101 and the electronic device main body may be mounted on the printed circuit board. The sensor module 201 does not necessarily have to include the sealing body 80.

[0064] The sensor element 101 of the sensor module 201 can be used in the usage environment of the semiconductor element 20 in the same manner as the sensor element 101 according to the first embodiment. The sensor element 101 of the sensor module 201 is used in a state in which it is sealed together with the semiconductor element 20 in the sealing body 80. Therefore, in the usage environment of the semiconductor element 20, the cumulative load due to temperature and humidity applied to the sensor element 101 is substantially equivalent to the cumulative load due to temperature and humidity applied to the semiconductor element 20. In the sensor module 201, by comparing the correlation data regarding the resistance value between the pair of electrodes 2 acquired by the sensor element 101 in the usage environment of the semiconductor element 20 with the correlation data regarding the resistance value between the pair of electrodes 2 acquired in advance in a reference environment having temperature and humidity conditions equivalent to or stricter than the guaranteed environment of the semiconductor element 20, it is possible to estimate whether the cumulative load due to temperature and humidity applied to the semiconductor element 20 in the usage environment of the semiconductor element 20 is equivalent to the cumulative load due to temperature and humidity applied to the semiconductor element 20 in the guaranteed environment.

[0065] The sensor module 201 may include a plurality of sensor elements 101 sealed by the same sealing body 80. Preferably, the plurality of sensor elements 101 are provided so that the degree of bleed-out of the additive differs from one another. In this case, it is preferable to acquire the correlation data in advance for each of the plurality of sensor elements 101 in the guaranteed environment of the semiconductor element 20, and compare this with the correlation data acquired in the usage environment of the semiconductor element 20.

[0066] Third Embodiment As shown in Figures 9 and 10, an electronic device 501 according to a third embodiment includes, for example, a sensor module 201, a measurement device 300, and an output device 400.

[0067] The measuring device 300 measures the resistance value between the pair of electrodes 2 of the sensor element 101 included in the sensor module 201 and outputs the measurement result to the output device 400. The measuring device 300 includes, for example, a voltmeter 301, an ammeter 302, and a power supply 303. The voltmeter 301 measures the voltage applied between the pair of electrodes 2 of the sensor element 101 by the power supply 303. The ammeter 302 measures the current flowing through the pair of electrodes 2 of the sensor element 101. The measuring device 300 calculates the resistance value from the measurement results of the voltmeter 301 and the ammeter 302, for example. The power supply 303 is, for example, a DC stabilized power supply. The power supply 303 may be an AC power supply or a battery. The power supply 303 does not have to be included in the measuring device 300. The sensor module 201 may include a voltage application mechanism configured to apply a voltage between the pair of electrodes 2 of the sensor element 101. Such a voltage application mechanism may be arranged outside the sensor module 201 and the measuring device 300 .

[0068] The output device 400 outputs to the electronic device 501 or its user a detection result that the resistance value measured by the measurement device 300 has fallen below the reference resistance. The output device 400 may be capable of outputting a cumulative load applied to the electronic device body due to the temperature and humidity of the usage environment of the electronic device 501, which is estimated based on the resistance value measured by the measurement device 300.

[0069] The output device 400 includes, for example, at least one of a recording device, an analyzing device, and a notifying device. The recording device stores correlation data between the cumulative load due to temperature and humidity applied to the sensor element 101, which is acquired in advance in a reference environment, and the resistance value between the pair of electrodes 2, or the reference resistance and short-circuit time of the sensor element 101 derived from the correlation data. The recording device may store an analysis program executed by the analyzing device.

[0070] The recording device can record, for example, at least one of the measurement results from the measurement device 300 and the analysis results from the analysis device. The storage device includes, for example, at least one of an HDD and an SSD.

[0071] For example, based on the resistance value measured by the measuring device 300 and the correlation data recorded in the recording device, the analysis device detects the short-circuit time of the sensor element 101 in the usage environment of the electronic device 501 (the time when the resistance value measured by the measuring device 300 falls below the reference resistance), or estimates the cumulative load applied to the electronic device body due to the temperature and humidity of the usage environment of the electronic device 501. The analysis device outputs the analysis result to at least one of the notification device and the recording device. The analysis device includes, for example, a microprocessor.

[0072] The notification device notifies the user of at least one of the measurement results by the measurement device 300 and the analysis results by the analysis device. The notification device includes, for example, at least one of a liquid crystal display, an LED (Light Emitting Diode) indicator, a speaker, and a buzzer.

[0073] The measurement interval of the measuring device 300 can be set arbitrarily. The output device 400 may output the detection result only when the resistance value measured by the measuring device 300 falls below the reference resistance. The output device 400 may output or record the resistance value measured by the measuring device 300 at each measurement interval of the measuring device 300.

[0074] <Modification of Electronic Device> Fig. 11 is a diagram showing a modification of the electronic device according to embodiment 3. As shown in Fig. 11, electronic device 502 has the same configuration and effects as electronic device 501 according to embodiment 3 above, unless otherwise specified. Therefore, the same components as those in embodiment 3 above are denoted by the same reference numerals, and description thereof will not be repeated.

[0075] The electronic device 502 includes a sensor module 202. The sensor module 202 includes a plurality of sensor elements. Two sensor elements 101A and 101B are illustrated in Fig. 11. The number of sensor elements included in the sensor module 202 may be any number equal to or greater than two.

[0076] The plurality of sensor elements are provided so that the degree of bleed-out of the additive differs from one another. From a different perspective, the plurality of sensor elements are provided so that the short-circuit times differ from one another. For example, the plurality of sensor elements differ from one another in at least one of the amount of additive added to the resin film 3 and the material constituting the resin film 3. For example, the amount of red phosphorus-based flame retardant added to the resin film 3 of sensor element 101A is greater than the amount of red phosphorus-based flame retardant added to the resin film 3 of sensor element 101B. In this case, the short-circuit time of sensor element 101A is shorter than the short-circuit time of sensor element 101B.

[0077] In the electronic device 502, it is preferable to acquire in advance correlation data between the resistance value between a pair of electrodes 2 and the cumulative load due to temperature and humidity applied in a reference environment for each of the plurality of sensor elements.

[0078] The resistance value between a pair of electrodes of each of the two sensor elements 101A and 101B is measured by, for example, one measuring device 300. A short circuit between each of the two sensor elements 101A and 101B is output by, for example, one output device 400. The output device 400 outputs a detection result for each sensor element that the resistance value measured by the measuring device 300 has fallen below a reference resistance.

[0079] In the electronic device 502, the graph shown in Fig. 12 can be created based on the measurement results of each sensor element. In the electronic device 502, from the graph shown in Fig. 12, it is possible to estimate not only the cumulative load applied to the electronic device body due to the temperature and humidity of the usage environment of the electronic device 502, but also fluctuations in the temperature and humidity of the usage environment of the electronic device 502.

[0080] Fig. 12 is a graph showing an example of evaluation results of the short circuit time (lifespan) of each sensor element in the warranty environment and the short circuit time of each sensor element in the usage environment for the electronic device 502 shown in Fig. 11. The horizontal axis of Fig. 12 represents the short circuit time (lifespan) (unit: years) of each sensor element in the warranty environment. The vertical axis of Fig. 12 represents the time (unit: years) from when each sensor element starts operating to when it shorts out in the usage environment of the electronic device 502.

[0081] 12, the electronic device 502 includes a semiconductor element with a guaranteed life of 10 years as the electronic device body. The electronic device 502 is an electronic device for which periodic maintenance inspections, for example, every two years, are recommended or required.

[0082] 12 , the electronic device 502 includes five or more sensor elements each having a different short-circuit time between a pair of electrodes 2 under a warranty environment. The sensor elements of the electronic device 502 are configured to short-circuit in two, four, six, eight, or ten years from the start of use under a warranty environment.

[0083] 12 , during maintenance inspection of the electronic device 502, the resistance value between a pair of electrodes 2 of each of the plurality of sensor elements is measured, and it is detected whether or not the pair of electrodes 2 of each of the plurality of sensor elements is short-circuited. Furthermore, by comparing the measurement result of each sensor element with the correlation data for each sensor element previously acquired in a reference environment, it is estimated whether or not the temperature and humidity of the usage environment of the electronic device 502 is higher than the temperature and humidity of the guaranteed environment, and further, fluctuations in the temperature and humidity of the usage environment of the electronic device 502 are detected.

[0084] 12, if the short-circuit duration of each sensor element detected in the usage environment of the electronic device 502 is the same as the short-circuit duration of each sensor element in the warranty environment, the dots indicating the relationship between the two are plotted on the dashed line. In Fig. 12, if the short-circuit duration of each sensor element detected in the usage environment of the electronic device 502 is shorter than the short-circuit duration of each sensor element in the warranty environment, the dots indicating the relationship between the two are plotted to the right of the dashed line.

[0085] In the example shown in FIG. 12 , the short circuit time of each sensor element in the usage environment of the electronic device 502 was shorter than the short circuit time in the respective warranty environments. A sensor element whose short circuit time in the warranty environment was 2 years shorted out after 1.5 years in the usage environment of the electronic device 502. A sensor element whose short circuit time in the warranty environment was 4 years shorted out after 3.0 years in the usage environment of the electronic device 502. A sensor element whose short circuit time in the warranty environment was 6 years shorted out after 4.6 years in the usage environment of the electronic device 502. A sensor element whose short circuit time in the warranty environment was 8 years shorted out after 6.1 years in the usage environment of the electronic device 502. A sensor element whose short circuit time in the warranty environment was 10 years shorted out after 7.6 years in the usage environment of the electronic device 502. From this, in the example shown in FIG. 12 , it was estimated that the temperature and humidity in the usage environment of the electronic device 502 were always higher than the temperature and humidity in the warranty environment.

[0086] 12, since the dots are arranged in a substantially straight line, it is estimated that the temperature and humidity of the environment in which the electronic device 502 is used is substantially constant. However, if the dots are arranged in a quadratic curve, it is estimated that the temperature and humidity of the environment in which the electronic device 502 is used has fluctuated.

[0087] In the example shown in Figure 12, it can be estimated that, for example, at the stage of the sixth-year periodic inspection, the temperature and humidity of the usage environment of the electronic device 502 will be higher and substantially constant than the temperature and humidity of the warranty environment. In this case, the user, manufacturer, or maintenance company of the electronic device 502 can plan at this point to replace or overhaul a part, such as a semiconductor element with a 10-year warranty life, that will soon reach the end of its warranty life. Furthermore, if a failure of a part becomes apparent because the user has not responded to the replacement or overhaul request, the graph shown in Figure 12 can be used to determine whether the failure of the part is due to use within the warranty period.

[0088] The number of sensor elements included in the electronic device 502 and the short-circuit time of each sensor element in the guaranteed environment may be determined arbitrarily, taking into consideration the guaranteed life of the electronic device 502 or the components included therein, the timing of regular inspections of the electronic device 502, and the prediction accuracy required of the electronic device 502 regarding the cumulative load on components, etc. due to the temperature and humidity of the environment in which the electronic device 502 is used.

[0089] 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 by the description of the above embodiments, and is intended to include all modifications within the meaning and scope of the claims.

[0090] REFERENCE SIGNS LIST 1 insulating substrate, 2 electrode, 3 resin film, 4 protective film, 5 conductive path, 6 internal electrode, 7 external electrode, 20 semiconductor element, 21 first end, 30 surface, 31 first portion, 32 second portion, 62 surface electrode portion, 63 side electrode portion, 80 sealing body, 81, 81A, 81B lead terminal, 83, 83A, 83B joining member, 101, 101A, 101B sensor element, 201, 202 sensor module, 300 measuring device, 301 voltmeter, 302 ammeter, 303 power supply, 400 output device, 501, 502 electronic device.

Claims

1. A sensor element comprising a pair of electrodes and a resin film separating the pair of electrodes, the resin film having a surface connecting the pair of electrodes, and an additive added to the resin film that bleeds out onto the surface and reduces the resistance value between the pair of electrodes.

2. The sensor element according to claim 1, wherein the additive is homogeneously dispersed in the resin film.

3. The sensor element according to claim 1 or 2, wherein the additive that bleeds out onto the surface forms a conductive path that electrically connects the pair of electrodes.

4. The sensor element according to any one of claims 1 to 3, wherein the additive is transformed into an electrolyte by at least one of oxidation and water absorption.

5. The sensor element according to any one of claims 1 to 4, wherein the additive is an inorganic additive.

6. The sensor element according to claim 5, wherein the additive is a red phosphorus-based flame retardant.

7. A sensor element as claimed in any one of claims 1 to 6, 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 a first end portion spaced apart from each other on the first surface of the insulating substrate and a second end portion spaced apart from each other on the second surface, wherein the resin film is disposed on the first surface, and wherein the resin film has a pair of first portions located on the first ends of each of the pair of electrodes and a second portion connecting the pair of first portions.

8. The sensor element according to any one of claims 1 to 7, further comprising a protective film covering the surface of the resin film, the protective film having electrical insulating properties and being made of a material different from that of the resin film.

9. A sensor module that detects a cumulative load applied to an electronic device main body in the environment in which the electronic device main body is used, comprising: at least one sensor element; the electronic device main body; a plurality of lead terminals; and a sealing body that seals the sensor element, the electronic device main body, and a portion of each of the plurality of lead terminals, wherein the at least one sensor element is a sensor element as defined in any one of claims 1 to 8, and the plurality of lead terminals include a pair of lead terminals electrically connected to each of the pair of electrodes of the at least one sensor element.

10. An electronic device comprising: the sensor module according to claim 9; a measuring device for measuring the resistance value between the pair of lead terminals; and an output device for outputting a detection result that the resistance value has fallen below a reference resistance.

11. An electronic device comprising the sensor module according to claim 9, wherein the sensor module comprises a plurality of the sensor elements, and further comprising: a measuring device that measures the resistance value between the pair of electrodes of each of the plurality of sensor elements; and an output device that outputs a detection result that the resistance value of each of the plurality of sensor elements has fallen below a reference resistance, wherein the plurality of sensor elements are arranged so that the degree of bleed-out of the additive differs from one another.

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