JP2024044355A - Hydrogen sulfide defect risk detection device and sample used therefor - Google Patents

Abstract

[Problem] To provide a hydrogen sulfide defect risk detection device and a sample used therein, which can detect the risk of defects occurring in printed circuit boards and the like due to corrosion caused by hydrogen sulfide with a simple configuration and simple judgment criteria. [Solution] A defect risk detection device 100 includes a measured member 114 including a light-transmitting member 116 and a silver film 118, a light-emitting unit 102 that irradiates light onto the measured member, a light-detecting unit 106 that detects the light transmitted through the silver film, a measurement terminal that generates a voltage corresponding to the current flowing through the light-detecting unit when the measured member is irradiated with light from the light-emitting unit, a measurement unit that measures the voltage of the measurement terminal, and a detection unit that detects the risk of defects occurring in printed circuit boards arranged around the measured member due to corrosion caused by hydrogen sulfide based on the measured voltage, and the detection unit detects the risk by comparing the measured voltage with a threshold value. This makes it possible to detect the defect risk with a simple configuration and simple judgment criteria. [Selected Figure] Figure 1

Description

TECHNICAL FIELD The present invention relates to a hydrogen sulfide failure risk detection device for detecting the risk of failure occurring in a printed circuit board or the like due to corrosion caused by hydrogen sulfide, and a sample used therein.

Hydrogen sulfide is easily generated in sewage treatment facilities and the like, and metal parts (electrical wiring patterns, etc.) of printed circuit boards used in electrical equipment (including electrical equipment) are corroded by hydrogen sulfide. When the metal parts of a printed circuit board are corroded by hydrogen sulfide, problems such as short circuits between adjacent wiring patterns and failures occur. In order to maintain the installed electrical equipment, it is preferable to monitor the concentration of hydrogen sulfide in the installation environment and detect signs of malfunctions due to corrosion caused by hydrogen sulfide.

The EcoChecker (registered trademark) II manufactured by Eurofins FQL Co., Ltd. is known as a method for diagnosing the presence or absence of corrosive substances in the atmosphere and the degree of corrosion. It contains five types of test metal pieces (silver, copper, iron-nickel alloy, aluminum, and iron). After exposing these metal pieces to the measurement environment for a certain period of time (one month), the presence or absence of corrosive gases and the approximate degree of corrosion (corresponding to the approximate concentration of corrosive gases) are determined by comparing the discoloration of the test metal pieces with the color samples provided with the product. If the exposed metal pieces are sent to Eurofins FQL Co., Ltd. for analysis, for example, a hydrogen sulfide concentration (approximate concentration) based on the results of a quantitative analysis of the amount of corrosion of silver using fluorescent X-ray analysis or the like is reported.

The following Patent Document 1 also discloses a corrosive environment monitoring device. This corrosive environment monitoring device constantly monitors the resistance of a silver printed circuit board pattern, and monitors the increase in resistance value caused by the pattern corroding (silver changing into silver oxide), thereby monitoring the concentration of corrosive substances (hydrogen sulfide) in the environment over a long period of time.

Patent Document 2 listed below discloses an environmental measurement device that measures corrosive gas in the atmosphere with high accuracy. This environmental measuring device detects weight increase due to silver sulfidation (sulfur content adhesion) using a QCM (Quartz Crystal Microbalance) sensor. A QCM sensor is a mass sensor that utilizes the property that when the mass of an electrode of a crystal resonator changes due to corrosion, the resonance frequency decreases in accordance with the amount of corrosion.

Patent Document 3 listed below discloses an environmental measurement device that can easily measure the concentration of a gas to be measured in a short time with high accuracy. Specifically, samples of metal thin films (for example, alloys made of Cu-Ag-Sn) that change color due to exposure to corrosive gases (for example, sulfur dioxide gas, hydrogen sulfide gas, chlorine gas, ammonia gas, nitrogen oxide gas) The corrosive gas concentration is estimated by photographing the degree of discoloration and analyzing the intensity and ratio of the three color elements (red, blue, green). For estimation, check the degree of discoloration by testing with various gases in advance.

JP 2019-113433 Publication International Publication No. 2013/186856 Japanese Patent Application Publication No. 2011-196985

In maintaining electrical equipment installed in an environment where hydrogen sulfide may be generated, it would be preferable to automatically and constantly monitor the progress of corrosion caused by hydrogen sulfide. As described above, in the method of exposing a test metal piece for a specified period of time and then performing X-ray fluorescence analysis, it is possible to estimate the hydrogen sulfide concentration during the sample exposure period (one month). However, in order to estimate the degree of exposure to hydrogen sulfide to estimate the risk of equipment malfunction, it is only possible to make an estimate using the one-month concentration estimate result as a representative value. Therefore, if there is a fluctuation in the hydrogen sulfide concentration, the estimate will be inaccurate. In addition, X-ray fluorescence analysis is required to estimate the hydrogen sulfide concentration, which cannot be determined on-site and requires an analysis fee.

In Patent Document 1, in order for the resistance value of the silver pattern to clearly increase, the cross section of the pattern needs to be completely sulfurized. That is, when an increase in the resistance value of the silver pattern is detected, it can be said that a problem has already occurred. Therefore, the sensitivity is too low to detect signs of malfunction due to corrosion of the printed circuit board.

Patent Document 2 requires a function to detect fluctuations in resonance frequency, and the equipment for this is expensive. It also reacts to weight increases due to phenomena other than sulfidation (for example, moisture adhesion or oxidation due to high humidity). Furthermore, since the resonant frequency is also affected by temperature changes, the accuracy is not sufficient as a method for detecting hydrogen sulfide.

In Patent Document 3, detection is based on discoloration of the sample surface, making it highly sensitive and capable of evaluating multiple gases. However, it requires photographing the sample, decomposing it into each color element, and performing calculations. In addition, a dedicated alloy substrate is required for evaluation, and the degree of discoloration must be confirmed in advance through tests with various gases, making the device expensive.

Therefore, an object of the present invention is to provide a hydrogen sulfide failure risk detection device that can detect the risk of failure in printed circuit boards, etc. due to corrosion caused by hydrogen sulfide, with a simple configuration and simple judgment criteria, and a sample used therein. shall be.

The defect risk detection device according to a first aspect of the present invention includes a measured member including a translucent member and a silver film disposed on the surface of the translucent member, a light emitting unit that irradiates light onto the measured member, a light detecting unit that detects the light that has passed through the silver film contained in the measured member, a measurement terminal that generates a voltage corresponding to the current flowing through the light detecting unit when the measured member is irradiated with light from the light emitting unit, a measurement unit that measures the voltage of the measurement terminal, and a detection unit that detects the risk of a defect occurring due to corrosion caused by hydrogen sulfide in a printed circuit board disposed around the measured member based on the voltage measured by the measurement unit, and the detection unit detects the risk by comparing the voltage measured by the measurement unit with a threshold value.

Thereby, with a simple configuration and simple criteria, it is possible to detect the risk of a malfunction occurring in a printed circuit board or the like due to corrosion caused by hydrogen sulfide (that is, malfunction risk). In other words, the silver film is irradiated with light and the measurement value (voltage) representing the transmittance is compared with a single threshold.The judgment is based on a simple criterion, so the measurement is repeated over a certain period of time and the time series There is no need to record data, and no complicated processing such as measuring or estimating the concentration of hydrogen sulfide is necessary. Furthermore, an inexpensive malfunction risk detection device can be realized. Therefore, monitoring of malfunction risks in multiple monitoring targets can be realized at low cost.

Preferably, the light-emitting unit includes a light-emitting diode, the light-detecting unit includes a phototransistor, and the measured member is disposed on an optical path through which light emitted from the light-emitting diode passes before being received by the phototransistor, with the surface being perpendicular to the optical path. This makes it easy to configure a malfunction risk detection device.

More preferably, the thickness of the silver film is 50 nm or more and 1000 nm or less. This allows the occurrence of malfunction risks to be detected with high accuracy. Furthermore, by adjusting the thickness of the silver film, it becomes possible to detect when corrosion due to hydrogen sulfide has reached a desired level.

More preferably, the thickness of the silver film is between 100 nm and 500 nm. This allows the occurrence of a defect risk to be detected more accurately.

A defect risk detection device according to a second aspect of the present invention includes a first measured member including a first translucent member and a silver film of a first thickness arranged on the surface of the first translucent member, a first light-emitting unit that irradiates light onto the first measured member, a first light-detecting unit that detects light that has passed through the silver film included in the first measured member, a first measurement terminal that generates a voltage corresponding to a current flowing through the first light-detecting unit when light is irradiated onto the first measured member from the first light-emitting unit, a first measurement unit that measures the voltage of the first measurement terminal, a first detection unit that detects a first risk of a defect occurring due to corrosion by hydrogen sulfide in a printed circuit board arranged around the first measured member based on the voltage measured by the first measurement unit, and a second measured member including a second translucent member and a silver film of a second thickness arranged on the surface of the second translucent member. The device includes a member, a second light-emitting unit that irradiates light onto a second measured member, a second light-detecting unit that detects light that has passed through a silver film included in the second measured member, a second measuring terminal that generates a voltage corresponding to the current flowing through the second light-detecting unit when the second measured member is irradiated with light from the second light-emitting unit, a second measuring unit that measures the voltage of the second measuring terminal, and a second detecting unit that detects a second risk of a defect caused by corrosion due to hydrogen sulfide on a printed circuit board arranged around the second measured member based on the voltage measured by the second measuring unit, and the first detecting unit detects the first risk by comparing the voltage measured by the first measuring unit with a threshold value, and the second detecting unit detects the second risk by comparing the voltage measured by the second measuring unit with a threshold value. This makes it possible to determine different levels of defect risk (i.e., the progression stage of corrosion due to hydrogen sulfide) in the same environment.

The sample according to the third aspect of the present invention is a sample for detecting the risk of a defect occurring in a printed circuit board due to corrosion caused by hydrogen sulfide, and includes a light-transmitting member and a silver film having a thickness of 50 nm to 1000 nm arranged on the surface of the light-transmitting member, and the risk is detected by determining the light transmittance of the silver film when it is arranged around the printed circuit board. This allows the occurrence of a defect risk to be detected with high accuracy.

According to the present invention, a hydrogen sulfide defect risk detection device can be realized that can detect the risk of defects occurring in printed circuit boards and the like due to corrosion caused by hydrogen sulfide using a simple configuration and simple judgment criteria. By using the defect risk detection device for automatic constant monitoring, it is possible to detect signs of defects before they occur.

FIG. 1 is a block diagram showing a schematic configuration of a malfunction risk detection device according to an embodiment of the present invention. FIG. 2 is a circuit diagram showing an optical detection system of the malfunction risk detection device shown in FIG. FIG. 3 is a flowchart showing a malfunction risk detection process executed by the malfunction risk detection device shown in FIG. FIG. 4 is a cross-sectional view showing the configuration of a measured member according to a first modified example. FIG. 5 is a flowchart showing a defect risk detection process according to the third modification. FIG. 6 is a diagram showing the experimental results in a tabular format. FIG. 7 is a graph showing the experimental results.

In the following embodiments, identical parts are given the same reference numbers. Their names and functions are also the same. Therefore, detailed descriptions thereof will not be repeated.

The following (1) and (2) are known to be typical defects that occur when a printed circuit board is exposed to hydrogen sulfide.
(1) Copper sulfide advances (corrosively advances) from the patterns (wiring, lands, etc.) of the printed circuit board to their surroundings, reaching adjacent patterns and causing a short circuit.
(2) The entire cross section inside the printed circuit board pattern is sulfurized, causing the resistance value of that area to increase.
As a result of investigating past malfunctions, it was confirmed that in most cases malfunction (1) occurs before malfunction (2). Therefore, it would be preferable to detect a sign of malfunction (1) before it occurs. Hereinafter, the risk of malfunction (1), such as wiring shorting, occurring due to hydrogen sulfide corrosion of printed circuit boards and the like included in electrical equipment and the like installed in an environment where hydrogen sulfide can be generated, is referred to as malfunction risk due to hydrogen sulfide, or simply malfunction risk.

Normally, the distance between patterns in printed wiring is 100 μm or more, so even if exposed to a hydrogen sulfide environment, insulation deterioration (short circuit, etc.) will not occur as long as the corrosion progression distance is up to about 20 μm. It is known that if the hydrogen sulfide concentration time product is approximately 15,000 ppb/day or less, the corrosion progression distance will be 20 μm or less (see, for example, JP 2022-62304). The hydrogen sulfide concentration time product refers to the product (in ppb/day) of the number of days that have elapsed since the start of exposure to hydrogen sulfide and the time the hydrogen sulfide concentration is measured.

On the other hand, if the corrosion progression distance is 50 μm or more, the risk of malfunction increases. If the exposure period to the hydrogen sulfide environment becomes longer and the hydrogen sulfide concentration time product becomes approximately 10,000 ppb/day, the risk of malfunction can be considered to be high. The malfunction risk detection device according to the embodiment of the present invention detects the time when the exposure state reaches, for example, a hydrogen sulfide concentration time product of about 3,000 to 4,000 ppb/day, with a view to safety. If the hydrogen sulfide concentration time product becomes approximately 3,000 to 4,000 ppb/day, corrosion has progressed and it can be considered that the risk of malfunction is not high, but does occur.

(Configuration of malfunction risk detection device)
Referring to FIG. 1, a malfunction risk detection device 100 according to an embodiment of the present invention includes a light emitting unit 102 that emits light, a power supply unit 104 that supplies power to the light emitting unit 102, and a photodetector that detects light. 106, a control section 108, a storage section 110, a timer 112, and a member to be measured 114. The malfunction risk detection device 100 also includes a power source (not shown) for operating each part, and an operating device (not shown) for inputting instructions to the control unit 108. As the operating device, for example, a computer keyboard, mouse, touch panel, etc. can be used. FIG. 1 shows a printed circuit board 900 as an example of a target subject to corrosion caused by hydrogen sulfide.

The light-emitting unit 102 is realized by, for example, a light-emitting diode (hereinafter referred to as LED (Light Emitting Diode)). The light-emitting unit 102 is not limited to an LED, and may be any light-emitting element that can stably output light of a predetermined intensity in a predetermined direction for a predetermined time (for example, about 0.1 seconds to several seconds). The light-emitting unit 102 emits, for example, red light (for example, light with a central wavelength of 630 nm). Note that the light-emitting unit 102 may be capable of emitting light of at least a portion of the wavelengths of visible light (for example, 360 nm to 830 nm). The power supply unit 104 supplies power to the light-emitting unit 102 for turning on the light-emitting unit 102 under the control of the control unit 108.

The light detection unit 106 is realized by, for example, a phototransistor. The light detection unit 106 is not limited to a phototransistor, but may be any element that can detect the light emitted by the light emission unit 102 and output an electrical signal (e.g., voltage or current) whose magnitude corresponds to the intensity (amount of light). It is preferable that the center of the detection sensitivity of the light detection unit 106 is near the central wavelength (e.g., 630 nm) of the light emitted by the light emission unit 102.

The member to be measured 114 includes a light-transmitting member 116 and a thin silver film 118. The silver thin film 118 is arranged on one surface of the light-transmitting member 116. The member to be measured 114 is arranged such that the surface on which the silver thin film 118 is arranged faces the light emitting section 102 . The silver thin film 118 may be disposed on the entire surface of the light-transmitting member 116, or may be disposed on a part of the surface. Note that the member to be measured 114 may be arranged such that the surface on which the silver thin film 118 is arranged faces the light detection section 106. Further, the silver thin film 118 may be arranged on both sides of the light-transmitting member 116.

The light-transmitting member 116 is formed of a member with high light transmittance. Light emitted from the light emitting section 102 is transmitted through the transparent member 116. The light-transmitting member 116 is formed into a film shape, for example. The light-transmitting member 116 is made of resin such as polyethylene terephthalate (PET), polycarbonate (PC), or acrylic (PMMA), for example. Further, the light-transmitting member 116 may be made of glass.

The silver thin film 118 is made of silver (Ag). The silver thin film 118 is formed, for example, by depositing or sputtering silver on the surface of the light-transmitting member 116 to form a laminate. The silver thin film 118 may also be formed by silver plating (for example, electroplating) the surface of the light-transmitting member 116. The silver thin film 118 is for detecting hydrogen sulfide. As will be described later as an example, when silver is exposed to an environment in which hydrogen sulfide is present, the sulfurization of silver progresses over time, causing the color to change from the initial silver color to a transparent brown, and gradually the film becomes light-transmitting. The degree of exposure to hydrogen sulfide (hydrogen sulfide concentration time product (ppb/day)) until the film becomes transparent depends on the thickness of the silver thin film (the thicker the film, the larger the hydrogen sulfide concentration time product required to obtain light transparency). Therefore, by appropriately setting the thickness of the silver thin film, the arrival of any hydrogen sulfide concentration time product can be estimated in the exposed film sample.

If the silver thin film 118 is too thin, it is not preferable because it is transparent to light even when silver sulfidation has not progressed. For example, if it was less than 50 nm, it was visually confirmed that light was transmitted under natural light. Furthermore, if the silver thin film 118 is too thick, even if the sulfidation progresses from the surface, the sulfidation inside will not progress (that is, the sulfidation will not progress in the thickness direction throughout the film), resulting in no light transmittance. . The thickness of the silver thin film 118 can be 1 μm or less. The thickness of the silver thin film 118 is preferably in the range of 50 nm to 1000 nm. More preferably, the thickness of the silver thin film 118 is between 100 nm and 500 nm.

The silver thin film 118 is irradiated with the irradiation light Lin output from the light emitting section 102 . If the degree of hydrogen sulfide exposure is small and sulfidation of silver has not progressed, the irradiated light Lin from the light emitting section 102 is reflected by the silver thin film 118 and is not detected by the photodetecting section 106. As the degree of hydrogen sulfide exposure increases and silver sulfidation progresses, the light transmittance of the silver thin film 118 increases as described above, and the irradiated light Lin from the light emitting section 102 passes through the silver thin film 118 and the transparent member 116. The light is transmitted and detected by the light detection unit 106 as transmitted light Lout. As the sulfidation of silver progresses, the light transmittance increases, so the degree of hydrogen sulfide exposure, that is, the time product of hydrogen sulfide concentration can be evaluated based on the amount of transmitted light Lout detected by the light detection unit 106.

The light emitting section 102, the light detecting section 106, and the member to be measured 114 constitute a light detecting system. The optical detection system of the malfunction risk detection device 100 is placed, for example, near a printed circuit board 900 in an electrical device installed in an environment where hydrogen sulfide can be generated. Note that the light emitted from the light emitting section 102 is not limited to the inside of the electrical equipment and may be in any state where the light emitted from the light detecting section 106 is detected. It suffices if it is placed in an environment where it can be shielded. The power supply section 104, the control section 108, the storage section 110, and the timer 112 can be arranged at any location, and may be arranged inside the electrical equipment to be monitored or outside the electrical equipment.

The control unit 108 is, for example, a CPU (Central Processing Unit), and controls the output of the power supply unit 104 to turn on or off the light emitting unit 102. For example, when the control unit 108 outputs a high-level signal (for example, 5V) to the power supply unit 104, the power supply unit 104 supplies power to the light emitting unit 102. As a result, the light emitting section 102 lights up. When the control unit 108 outputs a low level signal (for example, 0V) to the power supply unit 104, the power supply unit 104 stops supplying power to the light emitting unit 102. As a result, the light emitting section 102 that was lit is turned off.

The control unit 108 also acquires the output signal of the light detection unit 106 at a predetermined timing. For example, if the light detection unit 106 has an A/D conversion function, the control unit 108 acquires digital data output from the light detection unit 106. If the light detection unit 106 outputs an analog signal, the control unit 108 samples the input analog signal at a predetermined time interval to generate digital data.

The storage unit 110 is a volatile or nonvolatile memory that stores data input from the control unit 108. The timer 112 receives a request from the control unit 108 and outputs information representing the current time (hereinafter simply referred to as the current time).

As described above, the irradiation light Lin emitted from the light emitting unit 102 is irradiated onto the member to be measured 114 (i.e., the silver thin film 118 on the transparent member 116), and the member to be measured 114 (i.e., the silver thin film 118 and the transparent member) 116) is detected by the light detection unit 106. The amount of light measured by the photodetector 106 changes depending on the state of the silver thin film 118 (the degree of progress of sulfurization). When the silver thin film 118 is corroded by hydrogen sulfide, the transmittance of light increases, so the measured value becomes larger. The degree of corrosion of the silver thin film 118 increases depending on the concentration of hydrogen sulfide in the surrounding environment and the passage of time after the member to be measured 114 is installed in the electrical equipment. Therefore, the corrosion state of the silver thin film 118 can be observed by periodically measuring the amount of light detected by the light detection unit 106 while the power supply unit 104 is controlled by the control unit 108 to turn on the light emitting unit 102. .

FIG. 2 shows an example of a light detection circuit using an LED as the light emitting section 102 and a phototransistor as the light detection section 106. Referring to FIG. 2, light emitting section 102 includes an LED 130 and a resistive element R1 connected in series between terminals 140 and 142. The photodetector 106 includes a phototransistor 132 and a resistance element R2 connected in series between terminals 144 and 146.

With the terminals 142 and 146 grounded, by applying a DC voltage from the power supply section 104 between the terminals 140 and 142 of the light emitting section 102, the LED 130 emits light (for example, red light). The light detection unit 106 transmits transmitted light Lout (emitted light (red light) from the light emitting unit 102 that has passed through the silver thin film 118) to the phototransistor 132 in a state where a predetermined DC voltage is applied between the terminals 144 and 146. When incident, the phototransistor 132 is turned on and current flows (current flows between terminals 144 and 146). The control unit 108 measures the voltage generated at the measurement terminal 134 due to the accompanying voltage drop (hereinafter referred to as generated voltage). Since the value of the current flowing through the phototransistor 132 depends on the amount of light incident on the phototransistor 132, the generated voltage measured at the measurement terminal 134 represents the amount of light incident on the phototransistor 132. Note that the resistance elements R1 and R2 may have appropriate resistance values depending on the LED 130 and the phototransistor 132. At least one of resistance elements R1 and R2 may be a variable resistor.

When the measurement starts, the thin silver film 118 of the measured member 114 is in an uncorroded state (hereinafter also referred to as the initial state). Therefore, the generated voltage is approximately 0 V. In the initial state of the thin silver film 118, the generated voltage may not be 0 V, so it is efficient if the generated voltage can be evaluated as a relative value. For example, if the circuit in FIG. 2 is adjusted so that the value of the generated voltage measured in the initial state of the silver of the thin silver film 118 becomes a predetermined value, the generated voltage can be evaluated as a relative value. The circuit in FIG. 2 is adjusted by adjusting the resistance value of either of the resistive elements R1 and R2.

(Detection process of defect risk)
The process of detecting a defect risk due to hydrogen sulfide in a printed circuit board of an electrical device, which is executed by the defect risk detection device 100 in Fig. 1, will be described below with reference to Fig. 3. As described above, the defect risk due to hydrogen sulfide is detected by detecting the time when the hydrogen sulfide concentration time product reaches about 3000 to 4000 ppb per day.

The processing shown in FIG. 3 is performed by the control unit 108 reading and executing a predetermined program stored in the storage unit 110 in advance. The light emitting unit 102 and the light detecting unit 106 constitute the circuit shown in FIG. ).

It is assumed that the storage unit 110 of the malfunction risk detection device 100 stores information for specifying the time at which measurement is to be performed (hereinafter referred to as measurement time information), a threshold Th, and a message. The measurement time information is arbitrary as long as it is specified depending on the timing at which the measurement is performed. For example, when measurements are performed at regular time intervals, the measurement time information only needs to be the start time and the time interval Δt. When measuring at a pre-specified time, the measurement time information may be any information that directly represents the time. Here, it is assumed that measurements are performed at predetermined time intervals (time intervals Δt).

The threshold value Th is a real number, and the circuit of FIG. If it has been adjusted, it is set to Th=2 (V), for example. The message includes a message notifying that a risk of malfunction due to hydrogen sulfide has occurred (hereinafter referred to as malfunction risk notification).

In step 300, the control unit 108 obtains the current time from the timer 112, refers to the measurement time information stored in the storage unit 110, and determines whether the measurement time has come (that is, the time interval since the previous measurement). Whether Δt has elapsed or not is determined. If it is determined that the measurement time has come, control moves to step 302. Otherwise, control transfers to step 308.

In step 302, the control unit 108 turns on the light emitting unit 102 and measures the voltage V1 generated at the measurement terminal 134. The measured generated voltage (hereinafter also referred to as measured voltage) V1 is stored in the storage unit 110. Thereafter, the control unit 108 turns off the light emitting unit 102, and control proceeds to step 304.

In step 304, the control unit 108 reads the measured voltage V1 and the threshold Th stored in the storage unit 110, and determines whether the measured voltage V1 is equal to or higher than the threshold Th (that is, V1≧Th1). do. If it is determined that V1≧Th1, the control moves to step 306. Otherwise (V1<Th1), control moves to step 308.

In step 306, the control unit 108 reads out a predetermined message (ie, malfunction risk notification) from the storage unit 110 and presents it. Control then transfers to step 308. As described above, the malfunction risk notification indicates that a malfunction risk has occurred. The threshold Th is set to Th=2 (V) as described above. As will be described later as an example, this value corresponds to the voltage generated by the light detection unit 106 when the hydrogen sulfide concentration time product reaches approximately 3000 to 4000 ppb/day, and detects the stage at which a risk of failure occurs. It is for. As mentioned above, it cannot be said that the risk of failure is high at the stage when the risk of failure occurs, but corrosion due to hydrogen sulfide is progressing, and if electrical equipment continues to be used in this environment, the risk of failure will increase.

If the defect risk detection device 100 is equipped with an audio output device or an image display device, the message can be presented as audio or an image. Data representing the message to be presented may be transmitted from the defect risk detection device 100 to an external audio output device or image display device via wired or wireless communication. This allows the message to be presented by an audio output device or image display device located in a management room, etc.

In step 308, the control unit 108 determines whether or not an instruction to end has been received. If an instruction to end has been received, the program ends. If not, control returns to step 300, and the above processing is repeated. The instruction to end is given, for example, by turning off the power of the malfunction risk detection device 100.

As described above, it is possible to automatically detect the occurrence of a risk of a malfunction due to hydrogen sulfide on a printed circuit board in an electrical device without calculating the hydrogen sulfide concentration in the surrounding environment in which the electrical device is placed. In other words, when the hydrogen sulfide concentration time product reaches approximately 3000 to 4000 ppb/day, the risk of failure is not high, but occurrences can be automatically monitored at all times, and even if the hydrogen sulfide concentration changes, the risk of failure will decrease. Occurrence can be detected with high accuracy. By detecting the occurrence of malfunction risks, countermeasures can be taken before the performance of electrical equipment deteriorates or breakdowns occur, and electrical equipment can be managed appropriately.

A simple optical system is adopted in which the measured member 114 has a simple configuration in which a thin silver film 118 is disposed on a light-transmitting member 116, and the measured member 114 is disposed between the light-emitting unit 102 and the light-detecting unit 106. Therefore, it is possible to realize an optical system that has a simple configuration, is easy to adjust, and is inexpensive, without using expensive parts such as lenses, mirrors, and prisms. Furthermore, by a simple judgment process of comparing a single measured voltage with a single threshold value, it is possible to easily detect that a predetermined hydrogen sulfide concentration time product has been reached, i.e., the occurrence of a malfunction risk. Therefore, there is no need to use high-performance elements in the control unit 108 and memory unit 110, and the malfunction risk detection device 100 can be realized inexpensively.

By observing the corrosion of the silver thin film 118 as a change in light transmittance (a change in generated voltage), it is possible to accurately detect the occurrence of a risk of failure due to hydrogen sulfide. Since the measurement result (generated voltage) is an electrical signal, remote monitoring is easily possible. Moreover, the malfunction risk detection device 100 can easily continue observation by simply replacing the member to be measured 114. For example, if the message (malfunction risk notification) presented in step 306 includes the fact that the member to be measured 114 needs to be replaced, the risk of malfunction due to hydrogen sulfide can be detected by replacing the member to be measured 114. Accuracy can be maintained at a high level. For example, when the message is presented in step 306, if some measure against hydrogen sulfide is taken (for example, replacing the printed circuit board, etc.) and the member to be measured 114 is replaced, the risk of failure will occur again (i.e., hydrogen sulfide concentration (when the time product reaches approximately 3000 to 4000 ppb/day) can be detected. Furthermore, even if the member to be measured 114 is replaced without taking measures against hydrogen sulfide, it is possible to detect when the hydrogen sulfide concentration time product reaches approximately 3000 to 4000 ppb/day from the time of replacement. When presented, it can be seen that the hydrogen sulfide concentration time product was about 6000 to 8000 ppb·day.

The above-mentioned value of threshold value Th (Th = 2 (V)) is an example and is not limited to this value. By conducting a preliminary experiment according to the thickness of the thin silver film 118 and the hydrogen sulfide concentration time product (ppb/day) to be detected, the threshold value Th can be set to an appropriate value. In other words, by adjusting the thickness of the thin silver film 118 on the translucent member 116, it is possible to detect when an arbitrary water sulfide concentration time product has been reached.

Although the above describes a case where measurement and judgment are performed automatically according to a predetermined schedule, this is not limiting. Measurement and judgment may also be performed when an operating switch or the like is operated by a person. This makes it possible to realize a malfunction risk detection device at even lower cost. Also, for example, malfunction risks can be detected by manual operation during patrol inspections by an administrator.

As described above, the member to be measured 114 includes the light-transmitting member 116 and the silver thin film 118 disposed on the surface of the light-transmitting member 116 and having a thickness of 50 nm or more and 1000 nm or less. The member to be measured 114 is disposed around the printed circuit board 900 and is used to detect the occurrence of a risk of failure by determining the light transmittance of the silver thin film 118. The member to be measured 114 is very effective in detecting occurrence of malfunction risk.

Alternatively, a binary determination circuit (such as a comparator) may be configured to compare the voltage obtained for each measurement with a threshold value, and the relay contact may be turned on or off based on its output value. For example, when a relay is turned on, a lamp may be lit or a buzzer may sound. The occurrence of a malfunction risk can be notified by lighting a lamp or sounding a buzzer. With this configuration, remote monitoring becomes possible very simply and at low cost.

In the above description, a case has been described in which a failure risk is detected by binary determination in which the presence or absence of a failure risk is determined by comparing the voltage obtained for each measurement with a threshold value, but the present invention is not limited to this. As described above, step 302 shown in FIG. 3 is repeatedly executed, so if the measured generated voltage is stored in the storage unit 110 in correspondence with the elapsed time from the start of measurement, a series of time-series data can be obtained. can get. By displaying time-series data as a graph on an image display device, you can not only determine whether the threshold has been reached, but also observe the voltage change until the threshold is reached, thereby reducing the risk of malfunctions. It will also be possible to monitor for signs.

When the door is opened during inspection of electrical equipment, for example, light from the outside may enter the inside of the equipment, and the light detection system may also be irradiated with light. In such a state, when the time comes to measure the generated voltage and the measurement is performed, the measured value will be higher than the actual value. Since the manager or the like can know in advance that the door will be opened, etc., and light from the outside will enter the inside of the equipment, the manager or the like can simply temporarily stop the malfunction risk detection device 100.

(First Modification)
In the above, the case where the measured member 114 in which the thickness of the silver thin film 118 is constant has been described, but the present invention is not limited to this. A plurality of silver thin films with different thicknesses may be used at the same time. For example, a plurality of silver thin films with different thicknesses may be arranged on the surface of one light-transmitting member. Referring to FIG. 4, the measured member 200 according to the first modification has silver thin films 204, 206, and 208 arranged on its surface. The thicknesses t1, t2, and t3 of the silver thin films 204, 206, and 208 are t1<t2<t3. The positions of the silver thin films 204, 206, and 208 on the light-transmitting member 202 are arbitrary.

In the measurement, the member to be measured 114 is replaced by the member to be measured 200 in the configuration shown in FIG. It is sufficient to operate the members to be measured 200 as shown in FIG. Note that measurement may be performed by fixing the member to be measured 200 and moving the light emitting section 102 and the light detecting section 106.

If the thickness of the silver thin film is different, the hydrogen sulfide concentration time when the light transmittance becomes the same (that is, when the generated voltage (the voltage of the measurement terminal 134 shown in FIG. 2) becomes the same) The products are different. Therefore, by using a plurality of silver thin films with different thicknesses like the member to be measured 200 and making judgments using the same threshold Th (for example, Th=2V), multiple levels of failure risk (i.e., different Hydrogen sulfide concentration time product) can be determined.

For example, by adjusting the thickness of the thin silver film 118 to be thinner, it is possible to detect a state in which corrosion due to hydrogen sulfide is progressing at a stage prior to the state in which a risk of malfunction due to hydrogen sulfide has occurred (a state in which a malfunction risk notification is presented), as described above. Also, by adjusting the thickness of the thin silver film 118 to be thicker, it is possible to detect a state in which the risk of malfunction due to hydrogen sulfide has increased at a stage after the state in which a risk of malfunction due to hydrogen sulfide has occurred.

(Second modification)
Although the case where one failure risk detection device 100 is installed in a predetermined environment has been described above, the present invention is not limited to this. A plurality of malfunction risk detection devices 100 using members 114 to be measured with silver thin films 118 having different thicknesses may be installed in a predetermined environment. For example, two defect risk detection devices 100 having the configurations shown in FIGS. 1 and 2 are prepared and installed in the same environment. However, the members to be measured 114 used in the two failure risk detection apparatuses 100 have silver thin films 118 of different thicknesses. In either malfunction risk detection device 100, the malfunction risk detection method is the same as that in FIG. 3, and for example, the same threshold Th (for example, Th=2V) is used.

Even if the silver thin film 118 is placed in the same hydrogen sulfide environment, that is, the degree of exposure to hydrogen sulfide (that is, the hydrogen sulfide concentration time product) is the same, the light transmittance of the silver thin film 118 will vary depending on the thickness of the silver thin film 118. , that is, the generated voltages are different. This means that even if the same generated voltage is measured, the hydrogen sulfide concentration time product differs depending on the thickness of the silver thin film 118. Therefore, in the same environment, by using thin silver films 118 of different thicknesses and determining the failure risk using the same threshold value, different hydrogen sulfide concentration time products can be detected, and different levels of failure risk can be determined. That is, by using a plurality of silver thin films 118 having different film thicknesses, as in the first modification, a state where a risk of failure due to hydrogen sulfide occurs (a state where a failure risk notification is presented) and corrosion due to hydrogen sulfide progresses. It is possible to detect conditions where the risk of failure due to hydrogen sulfide is high.

(Third Modification)
In the first modified example, a case has been described in which a plurality of thin silver films with different thicknesses are arranged on the surface of one light-transmitting member to determine a plurality of levels of risk of malfunction (i.e., different hydrogen sulfide concentration time products), but this is not limiting. A plurality of threshold values can also be used for a single measured member 114 to determine a plurality of levels of risk of malfunction. In the third modified example, in the same configuration as in Figures 1 and 2, a determination is made using a plurality of threshold values as shown in Figure 5.

In the flowchart shown in FIG. 5, steps 304 and 306 in the flowchart shown in FIG. 3 are replaced with steps 320 to 326. In FIG. 5, the processing of steps with the same reference numerals as in FIG. 3 are the same as in FIG. Therefore, in the following, the different points will be mainly explained without repeating redundant explanations. Here, it is assumed that the storage unit 110 stores a plurality of threshold values Thi (i=1 to n, where n is a natural number) and a message corresponding to each threshold value Thi.

As described above, in step 302, after lighting the light emitting unit 102 and measuring the generated voltage V1 at the measurement terminal 134, in step 320, the control unit 108 selects one of the plurality of threshold values stored in the storage unit 110. Read one maximum threshold value from . As will be described later, since step 320 is repeatedly executed, the threshold values are read so as not to overlap thresholds that have already been read. Assume that the threshold value Thi is read out. Control then transfers to step 322.

In step 322, the control unit 108 reads the measured voltage V1 stored in the storage unit 110 in step 302, and determines whether the measured voltage V1 is equal to or higher than the threshold value Thi (ie, V1≧Thi). If it is determined that V1≧Thi, control moves to step 324. Otherwise (V1<Thi), control moves to step 308.

In step 324, the control unit 108 reads out from the memory unit 110 the i-th message corresponding to the threshold value Thi read out in step 320 and presents it. Then, control proceeds to step 308. That is, once one message has been presented, control proceeds to step 308.

As described below, the light transmittance of the silver thin film 118 changes depending on the degree of exposure to hydrogen sulfide, i.e., the hydrogen sulfide concentration time product, and the generated voltage changes. Different threshold values correspond to different hydrogen sulfide concentration time products. Therefore, it is sufficient to store messages corresponding to the hydrogen sulfide concentration time products (i.e., threshold values). For example, as described above, a message notifying that corrosion due to hydrogen sulfide is progressing (hereinafter referred to as a corrosion progression warning) and a message notifying that the risk of malfunction due to hydrogen sulfide has increased (hereinafter referred to as a malfunction risk warning) can be set. The messages corresponding to the threshold values are, in ascending order of threshold values, a corrosion progression warning, a malfunction risk notification, and a malfunction risk warning.

In step 326, it is determined whether the determination process has been completed for all threshold values. If it is determined that the process has ended, control moves to step 308. Otherwise, control returns to step 320, where new threshold values are read out to avoid duplication and a determination process is performed, as described above.

As a result, when sulfurization of the silver thin film 118 is not progressing, no message is displayed, and when sulfurization of the silver thin film 118 progresses, for example, a corrosion progress warning, a malfunction risk notification, and a malfunction risk warning are displayed in that order. Note that the messages to be displayed are not limited to a corrosion progress warning, a malfunction risk notification, and a malfunction risk warning, and two types of messages may be displayed using two thresholds. Four or more thresholds may be used to display four or more types of messages.

The experimental results are presented below to demonstrate the effectiveness of the present invention. Measurements were performed in an environment where hydrogen sulfide was present using a malfunction risk detection device (see Figure 1) that employs an optical detection system with the circuit configuration shown in Figure 2.

For the light emitting unit 102, an LED that emits red light with a wavelength of 630 nm was used. A 900Ω resistor was used as the resistance element R1, and the voltage applied between the terminals 140 and 142 was 5V DC. A phototransistor was used for the light detection section 106. A 12.5 kΩ resistor was used as the resistance element R2, and the voltage applied between the terminals 144 and 146 was 5 VDC. A polyethylene terephthalate (PET) film was used as the light-transmitting member 116, and a thin silver film 118 with a thickness of 100 nm was formed on the surface of the film by sputtering to form a member to be measured 114 (hereinafter referred to as a film sample). The threshold value Th was set to 2V. An exposure test was conducted using the produced film sample. That is, a hydrogen sulfide concentration measuring device was separately prepared, and while measuring the hydrogen sulfide concentration, the produced film sample was exposed to hydrogen sulfide over a time product of hydrogen sulfide concentration of 400 to 4000 ppb/day.

The experimental results are shown in FIGS. 6 and 7. FIG. 6 shows the results of visual observation of the film sample (ie, the member to be measured 114) that changed over time. In FIG. 7, the generated voltage (ie, measured voltage) corresponding to the hydrogen sulfide concentration time product is plotted using black squares. The measured voltage on the vertical axis is a relative value with the generated voltage measured in the initial state of the silver thin film as a reference value. During the period when the hydrogen sulfide concentration time product is less than 1000 ppb/day, the surface of the film sample (i.e., the surface on the thin silver film side) turns brown, but the back surface (i.e., the surface on the PET film side) remains mostly silver. there were. On the other hand, when the hydrogen sulfide concentration time product exceeded 2500 ppb/day, the back surface of the film sample turned brown, and it became possible to visually confirm that light was passing through the film sample.

The results shown in FIG. 7 also show that the sulfidation of the silver thin film portion of the film sample progresses in the direction of the thin film thickness, and as the light transmittance increases, the measured voltage (ie, the generated voltage) increases. From FIG. 7, it can be seen that if the generated voltage of 2V is taken as the threshold value Th (see the broken line in FIG. 7), it can be quantitatively determined that the exposure has reached approximately 3000 to 4000 ppb·day. If the generated voltage has not reached the threshold Th (i.e. 2V), it is determined that the predetermined hydrogen sulfide concentration time product (i.e. 3000 to 4000 ppb/day) has not been reached, that is, there is no risk of failure. can. Therefore, you can continue exposure using the same film sample and check next time.

The experimental results shown in Figures 6 and 7 are for a case where a film sample with a silver thin film thickness of 100 nm was used. By changing the thickness of the silver thin film, it is possible to determine the occurrence of different hydrogen sulfide exposure risks (i.e., the arrival of different hydrogen sulfide concentration-time products). For example, when using the same threshold value Th (e.g., 2 V), if a film sample with a silver thin film thickness thinner than 100 nm is used, the light transmittance of the silver thin film increases and the generated voltage reaches the threshold value Th for hydrogen sulfide concentration-time products smaller than 3000 to 4000 ppb-days. If a film sample with a silver thin film thicker than 100 nm is used, the light transmittance of the silver thin film increases and the generated voltage reaches the threshold value Th for hydrogen sulfide concentration-time products larger than 3000 to 4000 ppb-days.

For a film sample using a silver thin film with a thickness different from 100 nm, the threshold value Th for determining that the hydrogen sulfide concentration time product has reached 3000 to 4000 ppb/day is a value different from 2 V. . For film samples using thin silver films with a thickness different from 100 nm, an exposure test was conducted in the same manner as above, and in the same manner as shown in FIGS. 6 and 7, light transmittance was obtained in the thin silver film. What is necessary is to check the hydrogen sulfide concentration time product and determine the threshold value Th for determining that the predetermined hydrogen sulfide concentration time product has been reached.

Although the present invention has been described above by describing the embodiments, the above-described embodiments are merely examples, and the present invention is not limited to the above-described embodiments. The scope of the present invention is indicated by each claim, with reference to the description of the detailed description of the invention, and all changes within the scope and meaning equivalent to the words described therein are defined. include.

100 Malfunction risk detection device 102 Light emitting unit 104 Power supply unit 106 Light detection unit 108 Control unit 110 Storage unit 112 Timer 114, 200 Member to be measured 116, 202 Transparent member 118, 204, 206, 208 Silver thin film 130 LED
132 Phototransistor 134 Measurement terminals 140, 142, 144, 146 Terminal 900 Printed circuit board Lin Irradiation light Lout Transmitted light R1, R2 Resistance element t1, t2, t3 Thickness

Claims (5)

a measurement target member including a light-transmitting member and a silver film disposed on a surface of the light-transmitting member;
A light emitting unit that irradiates light onto the member to be measured;
a light detection unit that detects light transmitted through the silver film included in the measurement target member;
a measurement terminal that generates a voltage corresponding to a current flowing through the light detection unit when the member to be measured is irradiated with light from the light emitting unit;
A measurement unit that measures a voltage at the measurement terminal;
a detection unit that detects a risk of a malfunction occurring due to corrosion caused by hydrogen sulfide in a printed circuit board arranged around the measured member based on the voltage measured by the measurement unit,
A malfunction risk detection device characterized in that the detection unit detects the risk by comparing the voltage measured by the measurement unit with a threshold value. the light emitting unit includes a light emitting diode;
the light detection unit includes a phototransistor;
The malfunction risk detection device described in claim 1, characterized in that the measured part is positioned on the optical path through which light emitted from the light-emitting diode passes before being received by the phototransistor, with the surface being perpendicular to the optical path. The defect risk detection device according to claim 1 or 2, characterized in that the thickness of the silver film is 50 nm or more and 1000 nm or less. a first measured member including a first transparent member and a silver film having a first thickness disposed on the surface of the first transparent member;
a first light emitting section that irradiates light to the first member to be measured;
a first light detection unit that detects light transmitted through the silver film included in the first member to be measured;
a first measurement terminal that generates a voltage according to a current flowing through the first light detection section when the first member to be measured is irradiated with light from the first light emitting section;
a first measurement unit that measures the voltage of the first measurement terminal;
a first detection unit that detects a first risk related to the occurrence of a malfunction due to corrosion due to hydrogen sulfide in a printed circuit board disposed around the first member to be measured, based on the voltage measured by the first measurement unit;
a second member to be measured including a second light-transmitting member and a silver film having a second thickness disposed on the surface of the second light-transmitting member;
a second light emitting unit that irradiates light to the second member to be measured;
a second light detection unit that detects light transmitted through the silver film included in the second member to be measured;
a second measurement terminal that generates a voltage according to the current flowing through the second light detection section in a state in which the second measured member is irradiated with light from the second light emitting section;
a second measurement unit that measures the voltage of the second measurement terminal;
a second detection unit that detects a second risk related to the occurrence of a malfunction due to corrosion due to hydrogen sulfide in the printed circuit board disposed around the second member to be measured, based on the voltage measured by the second measurement unit; including;
The first detection unit detects the first risk by comparing the voltage measured by the first measurement unit with a threshold,
The failure risk detection device, wherein the second detection unit detects the second risk by comparing the voltage measured by the second measurement unit with the threshold value. A sample for detecting the risk of malfunctions caused by hydrogen sulfide corrosion on printed circuit boards,
A translucent member;
a silver film disposed on the surface of the light-transmitting member and having a thickness of 50 nm or more and 1000 nm or less,
The sample is characterized in that the risk is detected by determining the light transmittance of the silver film while the sample is placed around the printed circuit board.

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