Deterioration detection device, deterioration sensor, electronic apparatus, and deterioration detection method

Abstract

A deterioration detection device (30) comprises: a DC power supply (11); a first transmission line (12) connected to a positive electrode of the DC power supply; a second transmission line (12) provided spaced apart from the first transmission line and connected to a negative electrode of the DC power supply; a resistor (14) having one end connected to the first transmission line and another end connected to the second transmission line; and a detection unit (9) for detecting deterioration of a circuit board, which is a detection target, on the basis of changes over time in a voltage across both ends of the resistor.

Description

Deterioration detection device, deterioration sensor, electronic device, and deterioration detection method

[0001] The present disclosure relates to a deterioration detection device, a deterioration sensor, an electronic device, and a deterioration detection method.

[0002] Electronic devices equipped with printed circuit boards (hereinafter simply referred to as "circuit boards") can deteriorate and malfunction due to factors such as the installation environment and the regional characteristics of the installation environment. For example, circuit board deterioration can be caused by corrosion of the wiring and metal parts of the circuit board due to corrosive gases, ion migration, and the adhesion of dust particles in the air to the wiring. Since such deterioration of circuit boards due to factors such as the installation environment of electronic devices occurs in the field, it is important to take preventive measures to minimize damage caused by deterioration at the time of development of electronic devices.

[0003] As a preventive measure against the above-mentioned problems, Patent Document 1 discloses a technology for detecting deterioration of a printed wiring board on which a plurality of conductors constituting part of an electronic circuit are printed and wired. In this technology, a deterioration detection electrode conductor is printed and formed at a position independent of the conductors constituting the electronic circuit, and deterioration of the conductors constituting the electronic circuit is detected from the change over time in electrical characteristics measured by this deterioration detection electrode conductor.

[0004] Japanese Patent Application Laid-Open No. 2001-358429

[0005] However, while conventional deterioration detection techniques, such as the technique disclosed in Patent Document 1, can detect permanent short circuits and disconnections that occur when deterioration actually occurs in a circuit board, they may not be able to detect temporary short circuits that occur when deterioration actually occurs in a circuit board. As a result, conventional deterioration detection techniques may overlook deterioration of a circuit board accompanied by a temporary short circuit.

[0006] Here, a "temporary short circuit" refers to a short circuit that occurs in a circuit board due to deterioration of the circuit board, and that disappears in a relatively short period of time when a large current flows instantaneously through a short-circuit path (bridge) formed by the short circuit, causing the short-circuit path to burn out due to Joule heat. A "permanent short circuit" refers to a short circuit in which the short-circuit path formed by the short circuit does not burn out due to Joule heat, and current continues to flow through the short-circuit path (or a short circuit that does not take Joule heat into consideration).

[0007] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a deterioration detection device that can detect deterioration of a circuit board by detecting a temporary short circuit that occurs in the circuit board.

[0008] The deterioration detection device according to the present disclosure is characterized by comprising a DC power supply, a first transmission line connected to the positive electrode of the DC power supply, a second transmission line spaced apart from the first transmission line and connected to the negative electrode of the DC power supply, a resistor having one end connected to the first transmission line and the other end connected to the second transmission line, and a detection unit that detects deterioration of a circuit board to be detected based on a change over time in voltage across the resistor.

[0009] According to the present disclosure, with the above-described configuration, it is possible to detect a temporary short circuit occurring in a circuit board, thereby detecting deterioration of the circuit board.

[0010] FIG. 4A is a diagram showing an example of the configuration of a deterioration detection system including a deterioration detection device according to embodiment 1. FIG. 4B is a diagram showing an example of the configuration of a deterioration detection system including a deterioration detection device according to embodiment 1. FIG. 4C is a diagram showing an example of the configuration of a deterioration sensor unit according to embodiment 1. FIG. 4D is a diagram showing an example of the configuration of a deterioration detection system including a deterioration detection device according to embodiment 2. FIG. 4A is a diagram showing an example of the configuration of a deterioration sensor unit according to embodiment 1. FIG. 4C is a diagram showing an example of the configuration of a deterioration detection system including a deterioration detection device according to embodiment 2.

[0011] Hereinafter, embodiments will be described in detail with reference to the drawings. Embodiment 1. Fig. 1 is a diagram showing an example of the configuration of a deterioration detection system including a deterioration detection device 30 according to embodiment 1. As shown in Fig. 1, the deterioration detection system includes a printed circuit board 1 and a deterioration detection device 30 that detects deterioration of the printed circuit board 1.

[0012] The printed circuit board 1 is a circuit board having an electronic circuit 2 formed on one surface thereof. The electronic circuit 2 is a circuit configured to realize a predetermined function using any electronic components, conductors, etc.

[0013] The deterioration detection device 30 includes a deterioration sensor unit 3 and an automatic control device 5, as shown in FIG.

[0014] The deterioration sensor unit 3 is a sensor (deterioration sensor) for detecting deterioration of the printed circuit board 1 on which the electronic circuit 2 is formed. In this example, the deterioration sensor unit 3 is a sensor for detecting deterioration of the printed circuit board 1 due to corrosion in particular.

[0015] 1 , the deterioration sensor unit 3 is provided on a printed circuit board 1 on which an electronic circuit 2 is formed. However, the deterioration sensor unit 3 is not electrically connected to the electronic circuit 2, and is provided on the printed circuit board 1 in a manner electrically independent from the electronic circuit 2. On the other hand, the deterioration sensor unit 3 is electrically connected to the automatic control device 5 by a connecting line such as a cable, and is able to send and receive various data to and from the automatic control device 5 via this connecting line.

[0016] 1, the deterioration sensor unit 3 is formed adjacent to the electronic circuit 2 on the printed circuit board 1, but this position where the deterioration sensor unit 3 is formed is merely an example. For example, the deterioration sensor unit 3 may be formed on a substrate different from the printed circuit board 1, since it is electrically independent from the electronic circuit 2.

[0017] For example, if a substrate different from the printed circuit board 1 is located adjacent to the printed circuit board 1, the deterioration sensor unit 3 may be formed on the substrate different from the printed circuit board 1. In this case, however, the substrate on which the deterioration sensor unit 3 is formed is installed in the same environment as the environment in which the printed circuit board 1 is installed. Here, the same environment as the environment in which the printed circuit board 1 is installed means an environment in which the printed circuit board 1 can come into contact with the same air as the air that the printed circuit board 1 comes into contact with, at least within the same area as the area in which the printed circuit board 1 is installed.

[0018] <Deterioration Sensor Unit 3> Fig. 2 is a diagram showing an example of the configuration of the deterioration sensor unit 3. As shown in Fig. 2, the deterioration sensor unit 3 includes, for example, a DC power supply 11, two transmission lines 12, a voltage monitoring unit 13, and a resistor 14.

[0019] The DC power supply 11 has a positive terminal connected to one of the two transmission lines 12 and a negative terminal connected to the other of the two transmission lines 12. The DC power supply 11 supplies a predetermined bias voltage to these two transmission lines 12.

[0020] Each of the two transmission lines 12 is configured as a differential transmission line. The two differential transmission lines 12 are provided on the printed circuit board 1 so as to be parallel (including substantially parallel) to each other with a predetermined gap therebetween, as shown in, for example, FIGS.

[0021] Each differential transmission path 12 is composed of two signal lines, and is configured so that currents of opposite phases flow through the two signal lines constituting one differential transmission path 12. Similarly, currents of opposite phases flow through the two signal lines constituting the other differential transmission path 12. As a result, even if external noise (ambient noise) is superimposed on the two differential transmission paths 12, the influence of the ambient noise can be canceled out.

[0022] In order to ensure accuracy in detecting deterioration of the printed circuit board 1, the two signal lines constituting each differential transmission path 12 are preferably made of the same type of metal material as the conductors constituting the electronic circuit 2. In each differential transmission path 12, the distance between the two signal lines is preferably as narrow as possible so that the effects of ambient noise can be accurately canceled out.

[0023] The resistor 14 is connected in series between the two differential transmission paths 12. That is, one end of the resistor 14 is connected to the high-voltage side of the two differential transmission paths 12 (the side connected to the positive electrode of the DC power supply 11), and the other end is connected to the low-voltage side of the two differential transmission paths 12 (the side connected to the negative electrode of the DC power supply 11).

[0024] The voltage monitoring unit 13 is configured by, for example, a voltmeter, and is connected to the resistor 14. The voltage monitoring unit 13 measures the voltage across the resistor 14. Note that, as the voltage monitoring unit 13, for example, a voltmeter with a function of amplifying the voltage across the resistor 14 (operational amplifier function) may be used.

[0025] 1 , the two differential transmission paths 12, the voltage monitoring unit 13, and the resistor 14 constitute a short-circuit detection differential circuit 4. In the first embodiment, the voltage monitoring unit 13 measures the voltage between the two differential transmission paths 12 that constitute the short-circuit detection differential circuit 4, i.e., the voltage across the resistor 14, to detect deterioration of the printed circuit board 1 due to corrosion.

[0026] Specifically, in the first embodiment, deterioration due to corrosion progresses in the printed circuit board 1 due to factors such as corrosive gas. As this deterioration progresses, impurities accumulate between the two differential transmission lines 12 that constitute the short-circuit detection differential circuit 4 in the deterioration sensor unit 3, forming a short circuit (bridge) between the two differential transmission lines 12. A large current flows instantaneously through this short circuit, and the short circuit is burned out by Joule heat generated at that time. In this way, a temporary short circuit occurs between the two differential transmission lines 12. The change over time in the voltage between the differential transmission lines 12 caused by this temporary short circuit is measured by the voltage monitoring unit 13.

[0027] Generally, each differential transmission path 12 provided on the printed circuit board 1 is covered with solder resist, but it is desirable to configure each differential transmission path 12 so that the portions that may be electrically short-circuited by corrosive gases or the like are not covered with solder resist.

[0028] <Automatic control device 5> As shown in Fig. 1, the automatic control device 5 is electrically connected to the deterioration sensor unit 3 by wire or wirelessly. There are no particular limitations on the installation location of the automatic control device 5 as long as it is electrically connected to the deterioration sensor unit 3. For example, the automatic control device 5 may be provided on the same substrate as the substrate on which the deterioration sensor unit 3 is formed. Alternatively, the automatic control device 5 may be provided at any location inside the electronic device on which the printed circuit board 1 is mounted. Furthermore, the automatic control device 5 may be provided in a predetermined system that is provided in a location physically separated from the deterioration sensor unit 3 or the electronic device on which the printed circuit board 1 is mounted.

[0029] The automatic control device 5 includes, for example, a control unit 6, a learning unit 7, a storage unit 8, a detection unit 9, and a notification unit 10, as shown in FIG.

[0030] The control unit 6 controls the overall operation of the automatic control device 5. For example, the control unit 6 controls the execution of each command and the input and output of signals.

[0031] The learning unit 7 learns and analyzes data indicating ambient noise that is superimposed on the deterioration sensor unit 3 from outside the deterioration sensor unit 3. As a result, the learning unit 7 generates a trained model that can output an optimal threshold voltage used for detecting deterioration in response to input data indicating ambient noise. Details of the learning unit 7 will be described later.

[0032] The storage unit 8 is configured by a RAM (Random Access Memory) or a ROM (Read Only Memory), and stores general-purpose data and instruction codes used when the automatic control device 5 operates.

[0033] The detection unit 9 detects deterioration due to corrosion of the printed circuit board 1 based on the voltage measured by the voltage monitoring unit 13 and information indicating the time when the voltage was measured. That is, the detection unit 9 detects deterioration due to corrosion of the printed circuit board 1 based on the change over time in the voltage across the resistor 14 measured by the voltage monitoring unit 13. For example, the detection unit 9 detects deterioration due to corrosion of the printed circuit board 1 when the voltage across the resistor 14 measured by the voltage monitoring unit 13 falls below a threshold voltage.

[0034] When the detector 9 detects deterioration of the printed circuit board 1 due to corrosion, the notifier 10 notifies the outside that the deterioration has been detected.

[0035] When the automatic control device 5 is provided on the same substrate as the substrate on which the deterioration sensor unit 3 is formed, the functions of each of the above-mentioned units of the automatic control device 5 are realized by dedicated circuits or the like that can be mounted on the substrate. Furthermore, when the automatic control device 5 is provided in a predetermined system that is provided in a location physically separated from the electronic device on which the deterioration sensor unit 3 or the printed circuit board 1 is mounted, the automatic control device 5 is configured by, for example, a PC (Personal Computer). In this case, the functions of the control unit 6, learning unit 7, detection unit 9, and notification unit 10 are realized by a CPU (Central Processing Unit) mounted on the PC executing a predetermined program that has been installed in the PC in advance.

[0036] In the above description, an example in which the detection unit 9 is provided in the automatic control device 5 has been described, but the detection unit 9 is not limited to this, and may be provided in the deterioration sensor unit 3.

[0037] In the above description, as shown in FIG. 1 , an example has been described in which the two differential transmission lines 12 constituting the short-circuit detection differential circuit 4 are formed on one surface of the printed circuit board 1. However, the formation of the two differential transmission lines 12 is not limited to this. For example, the two differential transmission lines 12 may be formed on both surfaces of the printed circuit board 1, as shown in FIG. 3 . In this case, the two differential transmission lines 12 are connected to each other by through-hole vias 15 provided in the printed circuit board 1.

[0038] In this case, a chip resistor may be provided on one surface of the printed circuit board 1, and this chip resistor may be used as the resistor 14. Specifically, one end of this chip resistor may be connected to the higher voltage side of the two differential transmission lines 12, and the other end may be connected to the lower voltage side of the two differential transmission lines 12. This configuration improves the degree of freedom in the circuit configuration of the short-circuit detection differential circuit 4.

[0039] <Example of Operation of Deterioration Detection Device 30> Next, an example of operation of the deterioration detection device 30 shown in Fig. 1 will be described. In the following description, it is assumed that a printed circuit board 1 on which an electronic circuit 2 is formed is mounted on an arbitrary electronic device (hereinafter also referred to as a "product"). It is also assumed that the deterioration sensor unit 3 is formed on the printed circuit board 1 as shown in Fig. 1. It is also assumed that the automatic control device 5 is installed in a location different from the location where the product on which the printed circuit board 1 is mounted is installed.

[0040] A product is installed in a given environment and begins to be used. When the product begins to be used, a deterioration reaction due to corrosion progresses on the printed circuit board 1 mounted on the product due to the influence of the installation environment of the product or the regional characteristics of the product.

[0041] Causes of corrosion include, for example, corrosion due to corrosive gases, ion migration, and adhesion of dust particles contained in the air to the printed circuit board 1 (electronic circuit 2). Examples of corrosive gases include sulfur oxides, nitrogen oxides, halogen gases, and ammonia. Corrosion factors due to regional influences include, for example, sea salt particles, snow-melting salts, acid rain, and condensation due to temperature fluctuations.

[0042] The deterioration sensor unit 3 is formed on the printed circuit board 1. That is, the deterioration sensor unit 3 is installed in the same environment as the environment in which the printed circuit board 1 is installed. Therefore, a corrosion reaction similar to the corrosion reaction that progresses in the printed circuit board 1 (electronic circuit 2) progresses in the deterioration sensor unit 3.

[0043] As the corrosion reaction progresses in the deterioration sensor unit 3, impurities begin to accumulate between the two differential transmission lines 12. This accumulation of impurities reduces the insulation resistance between the two differential transmission lines 12 in the deterioration sensor unit 3. As the corrosion reaction progresses further, a temporary short circuit occurs between the two differential transmission lines 12 in the deterioration sensor unit 3.

[0044] Specifically, impurities deposited between the two differential transmission paths 12 form a short circuit (bridge) connecting the two differential transmission paths 12, for example, at a location adjacent to the resistor 14. When a short circuit is formed, a large current flows instantaneously through the short circuit from the high-voltage side to the low-voltage side, and the Joule heat generated by this large current burns the short circuit.

[0045] 4A is a diagram showing a simulation of how the voltages applied to the two differential transmission lines 12 change with time elapsed since the product was installed in an arbitrary environment (hereinafter also referred to as "product installation time"). In FIG. 4A, the horizontal axis represents the product installation time, "V1" on the vertical axis represents the voltage applied to the differential transmission line 12 on the lower voltage side of the two differential transmission lines 12, and "V2" on the vertical axis represents the voltage applied to the differential transmission line 12 on the higher voltage side of the two differential transmission lines 12. Also, in FIG. 4A, "Vth" on the vertical axis represents the threshold voltage for the detection unit 9 to detect a temporary short circuit.

[0046] 4B is a diagram showing a simulation of how the voltage measured by the voltage monitoring unit 13 changes with the product installation time. In FIG. 4B, the horizontal axis indicates the product installation time, "V2-V1" indicated on the vertical axis indicates the voltage measured by the voltage monitoring unit 13, and "Vth" indicated on the vertical axis indicates the threshold voltage for the detection unit 9 to detect a temporary short circuit.

[0047] 4A, the difference between voltages V1 and V2 from the time t0 when the product is installed indicates the bias voltage indicated by the reference numeral 18. At this time, it is assumed that ambient noise coming from outside the product is superimposed on the two differential transmission paths 12. This ambient noise may be a cause of erroneous detection by the deterioration detection device 30 (detection unit 9).

[0048] For example, as shown in FIG. 4A, from time t0 to time t1, ambient noise is superimposed on the two differential transmission paths 12, and a voltage waveform as shown by the reference numeral 16, i.e., a voltage waveform in which voltages V1 and V2 momentarily increase or decrease, is observed.

[0049] At this time, in the deterioration sensor unit 3, the voltage monitoring unit 13 measures the voltage across the resistor 14, i.e., the voltage difference (V2-V1) between the two differential transmission lines 12. In this way, the voltage monitoring unit 13 measures the voltage difference between the two differential transmission lines 12, so even if ambient noise is superimposed on the two differential transmission lines 12 as shown in FIG. 4B , the measurement result itself is not affected by the ambient noise.

[0050] Thereafter, as corrosion progresses in the printed circuit board 1, a temporary short circuit occurs from time t2 to time t3 due to impurities deposited between the two differential transmission lines 12. Specifically, when the temporary short circuit occurs at time t2, the short circuit formed between the two differential transmission lines 12 is burned out by Joule heat at time t3.

[0051] The time (t3-t2) from time t2 when the temporary short circuit occurs to time t3 when the short circuit path is burned out by Joule heat is extremely short, and during this time, a voltage waveform is observed in which the voltage V2 or the voltage difference (V2-V1) momentarily drops, as shown by reference numeral 17 in Figure 4A or 4B. At this time, the voltage difference (V2-V1), i.e., the voltage across resistor 14, falls below the threshold voltage Vth.

[0052] When the voltage across the resistor 14 measured by the voltage monitoring unit 13 falls below the threshold voltage Vth, the detection unit 9 detects that a temporary short circuit has occurred between the two differential transmission paths 12 due to the progression of corrosion, thereby detecting deterioration of the printed circuit board 1 that is the target of detection.

[0053] At time t3, if the short-circuit path formed between the two differential transmission paths 12 burns out, a noise voltage (reference numeral 19 in FIGS. 4A and 4B ) may be generated, which is expressed as the product of the parasitic inductance L in each of the two differential transmission paths 12 and the time change di / dt of the current flowing through the short-circuit path. Therefore, in order to suppress such noise voltage 19, a noise removal filter may be added to the short-circuit detection differential circuit 4.

[0054] As described above, in the first embodiment, the detection unit 9 detects a temporary short circuit that occurs in the printed circuit board 1 based on the change over time in the voltage across the resistor 14 measured by the voltage monitoring unit 13, thereby making it possible to detect deterioration of the printed circuit board 1. Furthermore, at this time, the detection unit 9 uses the voltage across the resistor 14 measured by the voltage monitoring unit 13, i.e., the voltage difference (V2-V1) between the two differential transmission paths 12, for deterioration detection, and therefore is less susceptible to the influence of ambient noise during deterioration detection.

[0055] Furthermore, in the first embodiment, the two transmission lines 12 connected to the DC power supply 11 are configured as differential transmission lines. As a result, in the first embodiment, it is possible to expect the effect of reducing the influence of ambient noise also in each differential transmission line 12, and it is possible to further reduce the influence of ambient noise during deterioration detection.

[0056] In the above description, an example has been described in which the two transmission lines 12 connected to the DC power supply 11 are each configured as a differential transmission line 12. However, the two transmission lines 12 do not necessarily have to be configured as differential transmission lines as long as a bias voltage can be applied from the DC power supply 11. However, as described above, if the two transmission lines 12 are each configured as a differential transmission line 12, it is expected that the effect of reducing the influence of ambient noise can also be achieved in each differential transmission line 12, and the influence of ambient noise can be further reduced during deterioration detection.

[0057] Furthermore, in the above explanation, an example was described in which the deterioration sensor unit 3 is configured to include two differential transmission paths 12, but the deterioration sensor unit 3 may also be configured to include, for example, a twisted pair cable 20 as shown in Figure 5 instead of the two differential transmission paths 12.

[0058] When the deterioration sensor unit 3 is configured to include the twisted pair cable 20, it is necessary to remove a portion of the coating of the twisted pair cable 20 and expose the conductor to the outside air so that a temporary short circuit that occurs between the two twisted pair cables 20 can be detected. Even with this configuration, it is expected to be effective in reducing the influence of ambient noise, similar to the case where two differential transmission paths 12 are employed.

[0059] <Regarding Threshold Voltage> In the first embodiment, the threshold voltage Vth used by the detector 9 when detecting a temporary short circuit is determined based on the learning result by the learner 7, for example.

[0060] For example, when determining the threshold voltage Vth, the learning unit 7 first learns and analyzes the amount of change in voltage across the resistor 14 depending on the magnitude of ambient noise. At this time, if a noise component from the DC power supply 11 side is included in the ambient noise, the noise component from the DC power supply 11 side is removed from the ambient noise. The learning unit 7 may also determine the threshold value taking into consideration, as a margin, the influence of the product installation environment and the regional characteristics of the area where the product is installed.

[0061] For example, the learning unit 7 is configured with a neural network. The learning unit 7 is provided with the following learning data: ambient noise from which the noise component from the DC power supply 11 side has been removed, the amount of change in voltage across the resistor 14 before and after the ambient noise is superimposed, data indicating the installation environment of the product, data indicating the influence of the regional characteristics of the area where the product is installed, and the threshold voltage Vth.

[0062] The learning unit 7 learns and analyzes the given learning data, and generates a trained model that can estimate and output the optimal threshold voltage Vth in response to inputs of ambient noise from which noise components from the DC power supply 11 have been removed, data indicating the installation environment of the product, and data indicating the influence of regional characteristics of the area in which the product is installed.

[0063] The detection unit 9 inputs the ambient noise from which the noise component from the DC power supply 11 has been removed, data indicating the installation environment of the product, and data indicating the influence of regional characteristics of the area where the product is installed into the trained model, and acquires the threshold voltage Vth output from the trained model. The detection unit 9 then uses the acquired threshold voltage Vth to detect a temporary short circuit that has occurred on the printed circuit board 1. As a result, in the first embodiment, it is possible to detect a temporary short circuit based on an appropriate threshold voltage Vth that takes into consideration the magnitude of ambient noise superimposed from outside the product, the installation environment of the product, the influence of regional characteristics of the area where the product is installed, and the like.

[0064] Note that the learning data provided to the learning unit 7 does not necessarily include data indicating the installation environment of the product and data indicating the influence of regional characteristics of the area where the product is installed. In this case, the trained model generated by the learning unit 7 only needs to be able to estimate and output an optimal threshold voltage Vth in response to input of ambient noise from which noise components from the DC power supply 11 have been removed. However, as described above, if the learning data provided to the learning unit 7 includes data indicating the installation environment of the product and data indicating the influence of regional characteristics of the area where the product is installed, it is possible to obtain an appropriate threshold voltage Vth that takes into account the installation environment of the product and the influence of regional characteristics of the area where the product is installed, which is preferable.

[0065] The learning unit 7 may also learn and analyze statistical data of the voltage change across the resistor 14. This enables the detection unit 9 to not only detect a temporary short circuit but also estimate the cause of the temporary short circuit (estimate the short circuit mode).

[0066] For example, ion migration is a phenomenon in which metal ions dissolve into water due to an electrochemical reaction and move between electrodes, but metals can also corrode if the concentration of corrosive gas is high even without water. If there is a difference in the reaction rate or frequency of occurrence between these two corrosion reactions, it is expected that differences corresponding to these differences will also be seen in the statistical data of the voltage changes across the resistor 14.

[0067] Therefore, the learning unit 7 learns and analyzes, for example, statistical data of voltage changes across the resistor 14 and data indicating the cause of a temporary short circuit (short circuit mode) corresponding to the statistical data as learning data, and generates a learned model that can estimate and output the cause of a temporary short circuit (short circuit mode) in response to an input of voltage changes across the resistor 14.

[0068] The detection unit 9 inputs data indicating a change in voltage across the resistor 14 to the trained model, and acquires data indicating the cause of the temporary short circuit (short circuit mode) output from the trained model in response to this input. This enables the detection unit 9 to estimate the cause of the temporary short circuit (short circuit mode) in addition to detecting the temporary short circuit.

[0069] In the above description, an example has been described in which the learning unit 7 generates two types of trained models: a trained model capable of estimating and outputting the threshold voltage Vth, and a trained model capable of estimating and outputting the cause of a temporary short circuit (short circuit mode). However, the learning unit 7 does not necessarily need to generate these two types of trained models. For example, the learning unit 7 may generate only one of the two types of trained models.

[0070] In the above description, an example has been described in which the detection unit 9 detects deterioration of the printed circuit board 1 due to corrosion based on the change over time in the voltage across the resistor 14 measured by the voltage monitoring unit 13. However, the cause of deterioration detected by the detection unit 9 may be a cause other than corrosion. In other words, the detection unit 9 may detect deterioration of the printed circuit board 1 due to a cause other than corrosion as long as the cause causes a change over time in the voltage across the resistor 14.

[0071] As described above, according to the first embodiment, the deterioration detection device 30 includes the DC power supply 11, the first transmission line 12 connected to the positive electrode of the DC power supply 11, the second transmission line 12 provided at a distance from the first transmission line 12 and connected to the negative electrode of the DC power supply 11, the resistor 14 having one end connected to the first transmission line 12 and the other end connected to the second transmission line 12, and the detection unit 9 that detects deterioration of the circuit board (printed circuit board) 1 that is the detection target, based on a change over time in the voltage across the resistor 14. As a result, the deterioration detection device 30 according to the first embodiment can detect deterioration of the circuit board 1 by detecting a temporary short circuit that occurs in the circuit board 1.

[0072] Furthermore, the detection unit 9 detects a temporary short circuit that occurs between the first transmission line 12 and the second transmission line 12 based on a change over time in the voltage across the resistor 14, thereby detecting deterioration of the circuit board 1. In this way, the deterioration detection device 30 according to the first embodiment can accurately detect a temporary short circuit that occurs in the circuit board 1.

[0073] Furthermore, the detection unit 9 detects a temporary short circuit by detecting that the voltage across the resistor 14 has fallen below the threshold voltage Vth. This allows the deterioration detection device 30 according to the first embodiment to accurately detect a temporary short circuit that occurs in the circuit board 1.

[0074] The DC power supply 11, the first transmission line 12, the second transmission line 12, and the resistor 14 are provided on the circuit board 1. This allows the deterioration detection device 30 according to the first embodiment to accurately detect a temporary short circuit that occurs on the circuit board 1.

[0075] Furthermore, the first transmission line 12 is provided on one surface of the circuit board 1, and the second transmission line 12 is provided on the other surface of the circuit board 1, and the first transmission line 12 and the second transmission line 12 are connected to each other via a through-hole via 15 formed in the circuit board 1. This improves the degree of freedom in the circuit configuration of the short-circuit detection differential circuit 4 in the degradation detection device 30 according to the first embodiment.

[0076] The deterioration detection device 30 also includes a learning unit 7 that generates a trained model capable of estimating a threshold voltage corresponding to a change in voltage across the resistor 14 before and after input of data indicating noise input from outside to the first transmission line 12 and the second transmission line 12, and the detection unit 9 detects a temporary short circuit based on the threshold voltage estimated by the trained model in response to the input of data indicating noise. This allows the deterioration detection device 30 according to the first embodiment to detect a temporary short circuit based on the threshold voltage that takes into account the influence of noise.

[0077] The deterioration detection device 30 also includes a learning unit 7 that generates a trained model capable of estimating and outputting the cause of a temporary short circuit in response to input data indicating the change over time in the voltage across the resistor 14, and the detection unit 9 detects a temporary short circuit by detecting that the voltage across the resistor 14 has fallen below a threshold voltage, and estimates the cause of the temporary short circuit by inputting data indicating the change over time in the voltage across the resistor 14 to the trained model generated by the learning unit 7. As a result, the deterioration detection device 30 according to the first embodiment can not only detect a temporary short circuit but also estimate the cause of the temporary short circuit.

[0078] Furthermore, the first transmission line 12 and the second transmission line 12 are configured as differential transmission lines, which allows the deterioration detection device 30 according to the first embodiment to cancel the influence of external noise.

[0079] The differential transmission path is configured by the twisted pair cable 20. As a result, the deterioration detection device 30 according to the first embodiment can realize the differential transmission path with a simple configuration.

[0080] Furthermore, according to the first embodiment, the deterioration sensor (deterioration sensor unit) 3 includes a DC power supply 11, a first transmission line 12 connected to the positive electrode of the DC power supply 11, a second transmission line 12 provided at a distance from the first transmission line 12 and connected to the negative electrode of the DC power supply 11, a resistor 14 having one end connected to the first transmission line 12 and the other end connected to the second transmission line 12, a voltmeter (voltage monitoring unit) 13 that measures the voltage across the resistor 14, and a detection unit 9 that detects deterioration of the circuit board 1 that is the detection target, based on a change over time in the voltage measured by the voltmeter 13. As a result, the deterioration sensor 3 according to the first embodiment can detect deterioration of the circuit board 1 by detecting a temporary short circuit that occurs in the circuit board 1.

[0081] Embodiment 2 In the first embodiment, an example was described in which the deterioration sensor unit 3 constituting the deterioration detection device 30 is formed on the printed circuit board 1 that is the target of deterioration detection. In the second embodiment, an example will be described in which the deterioration sensor unit 3 constituting the deterioration detection device 30 is formed on a flexible substrate that is a substrate different from the printed circuit board 1 that is the target of deterioration detection.

[0082] 6 is a diagram showing an example of the configuration of a deterioration detection system including a deterioration detection device 30 according to embodiment 2. In embodiment 2, the deterioration sensor unit 3 constituting the deterioration detection device 30 is formed on a flexible printed circuit (FPC) 25, and is mounted together with this FPC 25 in an electronic device 40.

[0083] The electronic device 40 is a device having a predetermined function. In the configuration example shown in Fig. 6, a plurality of (here, three) printed circuit boards 1 are housed in the housing 21 of the electronic device 40. The predetermined function of the electronic device 40 is realized by the cooperation of these plurality of printed circuit boards 1.

[0084] The housing 21 of the electronic device 40 has a gap 22 formed therein for taking in, for example, outside air into the housing 21. The gap 22 is formed to a predetermined size, and wind containing dust, corrosive gas 24, and the like flow into the housing 21 from the outside through the gap 22.

[0085] Furthermore, a housing protrusion 23 is formed inside the housing 21. The housing protrusion 23 is provided at a position that blocks the flow of dust-laden wind, corrosive gas 24, and the like that have flowed into the housing 21 from the gap 22, for example, and causes these to accumulate at a specific location inside the housing 21. The housing protrusion 23 is also provided at a position that can protect the printed circuit board 1, for example, so that the printed circuit board 1 is not severely affected by the dust-laden wind, corrosive gas 24, and the like.

[0086] In the first embodiment, the deterioration sensor unit 3 is formed on the printed circuit board 1, which is the target of deterioration detection. However, some printed circuit boards 1 have a size or component arrangement that makes it impossible to mount the deterioration sensor unit 3. Therefore, in the second embodiment, the deterioration sensor unit 3 is provided on the FPC 25.

[0087] The FPC 25 is installed in the same environment as the environment in which the printed circuit board 1 is installed. The same environment as the environment in which the printed circuit board 1 is installed means an environment in which the FPC 25 can come into contact with the same air as the air that the printed circuit board 1 comes into contact with, at least within the same area as the area in which the printed circuit board 1 is installed.

[0088] The FPC 25 on which the deterioration sensor unit 3 is provided is provided near the top of the housing 21 along the inner wall of the housing 21, as shown in Fig. 6, for example. Note that Fig. 6 shows an example in which the FPC 25 is displayed as if it is visible from the outside of the housing 21, for ease of understanding, but in reality, the FPC 25 does not have to be visible from the outside of the housing 21.

[0089] In the second embodiment, the substrate on which the deterioration sensor unit 3 is formed is different from that in the first embodiment, but the configuration example of the deterioration sensor unit 3 itself and the configuration example of the automatic control device 5 are basically the same as the configuration example of the deterioration sensor unit 3 and the automatic control device 5 described in the first embodiment. In addition, the operation example of the deterioration detection device 30 according to the second embodiment is also basically the same as the operation example of the deterioration detection device 30 according to the first embodiment.

[0090] Note that, in the deterioration sensor unit 3 in the second embodiment, similarly to the first embodiment, the two transmission lines 12 connected to the DC power supply 11 may each be configured with a differential transmission line 12. Similarly to the first embodiment, the deterioration sensor unit 3 in the second embodiment may also be configured to include, for example, a twisted pair cable 20 as shown in FIG. 5 instead of the two differential transmission lines 12. In this case, in the second embodiment, the twisted pair cable 20 and the FPC 25 may be combined to form the deterioration sensor unit 3. Similarly to the first embodiment, the deterioration sensor unit 3 in the second embodiment may also be configured to include a detection unit 9.

[0091] Corrosion reactions due to the installation environment of electronic device 40 and the regional characteristics of the area where electronic device 40 is installed may occur in specific (biased) locations inside electronic device 40 due to the structure of electronic device 40 itself. In this case, depending on the installation position of deterioration sensor unit 3 inside electronic device 40, the accuracy of detecting deterioration occurring in printed circuit board 1 may be reduced. Furthermore, there is a possibility that sufficient space for installing deterioration sensor unit 3 may not be secured on printed circuit board 1 due to factors such as the size of printed circuit board 1 or component layout.

[0092] In this regard, in the second embodiment, the deterioration sensor unit 3 is formed on the FPC 25, so that the FPC 25 on which the deterioration sensor unit 3 is formed, or the twisted pair cable 20 and the FPC 25, can be effectively and flexibly installed inside the electronic device 40. Furthermore, in the second embodiment, this allows the deterioration sensor unit 3 to be placed around a location inside the electronic device 40 where a corrosion reaction is expected to progress in particular. Therefore, in the second embodiment, a temporary short circuit that occurs on the printed circuit board 1 mounted inside the electronic device 40 can be accurately detected, and a decrease in the accuracy of deterioration detection by the deterioration sensor unit 3 can be suppressed.

[0093] Furthermore, by configuring as described above, the deterioration sensor unit 3 can be mounted in a form that corresponds to the internal structure of the electronic device 40. As a result, in the second embodiment, even if there is a bias in the location inside the electronic device 40 where a corrosion reaction particularly progresses, or even if it is difficult to mount the deterioration sensor unit 3 on the printed circuit board 1, it is possible to accurately detect a temporary short circuit that occurs on the printed circuit board 1 mounted on the electronic device 40.

[0094] Furthermore, by configuring as described above, in the second embodiment, it is possible to reduce constraints on the implementation of the degradation sensor unit 3 when proceeding with the design and development of the electronic device 40. This leads to a reduction in the difficulty or cost involved in the design and development of the electronic device 40. Thus, in the second embodiment, the above-described effects can be expected not only after the electronic device 40 has started to be used, but also during the design and development stage of the electronic device 40.

[0095] As described above, according to the second embodiment, the DC power supply 11, the first transmission line 12, the second transmission line 12, and the resistor 14 are provided on a board that is different from the circuit board (printed circuit board) 1 and that is installed in the same environment as the environment in which the circuit board 1 is installed. As a result, the deterioration detection device 30 according to the second embodiment can accurately detect a temporary short circuit that occurs on the circuit board 1 even when there are installation constraints on the circuit board 1.

[0096] Furthermore, the substrate on which the DC power supply 11, the first transmission line 12, the second transmission line 12, and the resistor 14 are provided is an FPC (flexible printed circuit) 25. This improves the degree of freedom in the placement of the DC power supply 11, the first transmission line 12, the second transmission line 12, and the resistor 14 in the degradation detection device 30 according to the second embodiment.

[0097] According to the second embodiment, the electronic device 40 includes a housing 21 in which a circuit board 1 to be detected is installed, and a deterioration sensor unit 3 provided inside the housing 21. The deterioration sensor unit 3 includes a DC power supply 11, a first transmission line 12 connected to the positive electrode of the DC power supply 11, a second transmission line 12 provided at a distance from the first transmission line and connected to the negative electrode of the DC power supply 11, a resistor 14 having one end connected to the first transmission line 12 and the other end connected to the second transmission line 12, a voltmeter (voltage monitoring unit) 13 that measures the voltage across the resistor 14, and a detection unit 9 that detects deterioration of the circuit board 1 based on a change over time in the voltage measured by the voltmeter 13. As a result, the electronic device 40 according to the second embodiment can detect deterioration of the circuit board 1 by detecting a temporary short circuit that occurs in the circuit board 1.

[0098] Furthermore, according to the second embodiment, the DC power supply 11, the first transmission line 12, the second transmission line 12, the voltage monitoring unit 13, the resistor 14, and the detection unit 9 are provided on the FPC 25, which is a board different from the circuit board 1. This improves the degree of freedom in the placement of the DC power supply 11, the first transmission line 12, the second transmission line 12, the voltage monitoring unit 13, the resistor 14, and the detection unit 9 in the electronic device 40 according to the second embodiment.

[0099] In addition, the present disclosure allows for free combination of the embodiments, modification of any of the components of the embodiments, or omission of any of the components of the embodiments.

[0100] The present disclosure makes it possible to detect deterioration of a circuit board by detecting a temporary short circuit that occurs in the circuit board, and is suitable for use in deterioration detection devices, deterioration sensors, electronic devices, and deterioration detection methods.

[0101] 1 Printed circuit board (circuit board), 2 Electronic circuit, 3 Deterioration sensor unit (deterioration sensor), 4 Short circuit detection differential circuit, 5 Automatic control device, 6 Control unit, 7 Learning unit, 8 Memory unit, 9 Detection unit, 10 Notification unit, 11 DC power supply, 12 Transmission line (differential transmission line), 13 Voltage monitoring unit (voltmeter), 14 Resistor, 15 Through-hole via, 16 Voltage waveform, 17 Voltage waveform, 18 Bias voltage, 19 Noise voltage, 20 Twisted pair cable, 21 Housing, 22 Gap, 23 Housing protrusion, 24 Corrosive gas, 25 FPC, 30 Deterioration detection device, 40 Electronic device, V1 Voltage, V2 Voltage, Vth Threshold voltage.

Claims

1. A deterioration detection device comprising: a DC power supply; a first transmission line connected to a positive electrode of the DC power supply; a second transmission line spaced apart from the first transmission line and connected to a negative electrode of the DC power supply; a resistor having one end connected to the first transmission line and the other end connected to the second transmission line; and a detection unit that detects deterioration of a circuit board to be detected based on changes over time in voltage across the resistor.

2. The deterioration detection device according to claim 1, characterized in that the detection unit detects deterioration of the circuit board by detecting a temporary short circuit that occurs between the first transmission line and the second transmission line based on the change over time in the voltage across the resistor.

3. The deterioration detection device according to claim 2, characterized in that the detection unit detects the temporary short circuit by detecting that the voltage across the resistor falls below a threshold voltage.

4. A deterioration detection device as claimed in any one of claims 1 to 3, characterized in that the DC power supply, the first transmission line, the second transmission line, and the resistor are provided on the circuit board.

5. The deterioration detection device according to claim 4, characterized in that the first transmission line is provided on one side of the circuit board, the second transmission line is provided on the other side of the circuit board, and the first transmission line and the second transmission line are connected to each other via a through-hole via formed in the circuit board.

6. The deterioration detection device according to any one of claims 1 to 3, characterized in that the DC power supply, the first transmission line, the second transmission line, and the resistor are provided on a board that is different from the circuit board and is installed in the same environment as the circuit board.

7. The deterioration detection device according to claim 6, wherein the substrate on which the DC power supply, the first transmission line, the second transmission line, and the resistor are provided is a flexible substrate.

8. The deterioration detection device according to claim 3, further comprising a learning unit that generates a trained model capable of estimating a threshold voltage corresponding to an amount of change in voltage across the resistor before and after input of data indicating noise input from outside to the first transmission line and the second transmission line, and the detection unit detects the temporary short circuit based on the threshold voltage estimated by the trained model in response to the input of data indicating the noise.

9. The deterioration detection device according to claim 3, further comprising a learning unit that generates a trained model capable of estimating and outputting the cause of the temporary short circuit in response to input of data showing the change over time in the voltage across the resistor, wherein the detection unit detects the temporary short circuit by detecting that the voltage across the resistor has fallen below a threshold voltage, and estimates the cause of the temporary short circuit by inputting data showing the change over time in the voltage across the resistor to the trained model generated by the learning unit.

10. A deterioration detection device as claimed in any one of claims 1 to 9, characterized in that the first transmission line and the second transmission line are configured as differential transmission lines.

11. The deterioration detection device according to claim 10, characterized in that the differential transmission path is composed of a twisted pair cable.

12. A degradation sensor comprising: a DC power supply; a first transmission line connected to a positive electrode of the DC power supply; a second transmission line spaced apart from the first transmission line and connected to a negative electrode of the DC power supply; a resistor having one end connected to the first transmission line and the other end connected to the second transmission line; a voltmeter that measures the voltage across the resistor; and a detection unit that detects degradation of a circuit board to be detected based on a change over time in the voltage measured by the voltmeter.

13. An electronic device including a housing in which a circuit board to be detected is installed, and a deterioration sensor provided inside the housing, wherein the deterioration sensor comprises: a DC power source; a first transmission line connected to the positive electrode of the DC power source; a second transmission line provided at a distance from the first transmission line and connected to the negative electrode of the DC power source; a resistor having one end connected to the first transmission line and the other end connected to the second transmission line; a voltmeter that measures the voltage across the resistor; and a detection unit that detects deterioration of the circuit board based on the change over time in voltage measured by the voltmeter.

14. The electronic device according to claim 13, characterized in that the DC power supply, the first transmission line, the second transmission line, the resistor, the voltmeter, and the detection unit are provided on a flexible substrate that is a substrate different from the circuit board.

15. A degradation detection method using a degradation detection device including: a DC power supply; a first transmission line connected to the positive electrode of the DC power supply; a second transmission line spaced apart from the first transmission line and connected to the negative electrode of the DC power supply; a resistor having one end connected to the first transmission line and the other end connected to the second transmission line; and a detection unit, wherein the detection unit detects degradation of a circuit board to be detected based on a change over time in voltage across the resistor.

Images