Inspection device and inspection method

Abstract

The invention provides an inspection device and an inspection method which are beneficial for detecting abnormality of a capacitor with high precision. The inspection device includes: a voltage applying unit that applies a voltage to a capacitor and charges the capacitor; a current measurement unit that continuously measures the current of the capacitor during charging; and an abnormality detection unit that detects an abnormality in the capacitor on the basis of a regression line (Lr) derived from the logarithm of the current measurement values and the logarithm of the current measurement times in the determination time range during charging.

Description

Technical Field

[0001] The present invention relates to an inspection device and an inspection method for detecting abnormality of a capacitor. Background Art

[0002] Capacitors such as MLCC (Multi-Layer Ceramic Capacitor) and / or electronic components equipped with capacitors are usually shipped after undergoing inspections to detect defective products. In recent years, in particular, a large number of MLCCs are used in devices such as automobiles and / or communication equipment that require high performance and safety, and there is a desire to implement inspections that guarantee the reliability of a large number of MLCCs at a higher level.

[0003] Regarding such inspection, for example, Patent Document 1 discloses a defect detection device for the purpose of detecting and / or screening internal defects such as foreign matter and / or pinholes in a laminated ceramic capacitor in a short time. In addition, Patent Document 2 discloses a quality determination method for the purpose of determining the quality of a capacitor in a short time.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 09-152455

[0007] Patent Document 2: Japanese Patent Application Publication No. 2000-228337 Summary of the invention

[0008] Technical issues

[0009] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a technology useful for detecting abnormality of a capacitor with high accuracy.

[0010] Technical Solution

[0011] One embodiment of the present invention relates to an inspection device, which includes: a voltage application unit that applies a voltage to a capacitor to charge it; a current measuring unit that continuously measures the current of the capacitor being charged; and an abnormality detection unit that detects an abnormality of the capacitor based on a regression line derived from the logarithm of the measured value of the current within a determination time range during charging and the logarithm of the measurement time of the current.

[0012] The abnormality detection unit may detect the abnormality of the capacitor based on the consistency of the logarithm of the measured value of the current and the logarithm of the measurement time with respect to a regression line.

[0013] The abnormality detection unit may detect the abnormality of the capacitor based on a relationship between a logarithm of the current measurement value and at least one of an upper limit and a lower limit of an allowable current range determined based on a regression line over the determination time range.

[0014] The abnormality detection unit can also detect the abnormality of the capacitor based on a first regression line derived from the logarithm of the measured value of the current within a first judgment time range during charging and the logarithm of the measurement time of the current, and can also detect the abnormality of the capacitor based on a second regression line derived from the logarithm of the measured value of the current within a second judgment time range during charging and the logarithm of the measurement time of the current.

[0015] The voltage applying unit may apply a voltage to the capacitor with a first polarity to perform first polarity charging, and may apply a voltage to the capacitor with a second polarity which is opposite to the first polarity after the first polarity charging to perform second polarity charging. The current measuring unit may measure the current of the capacitor during the first polarity charging, i.e., the first polarity current, and may measure the current of the capacitor during the second polarity charging, i.e., the second polarity current. The abnormality detecting unit may detect the abnormality of the capacitor based on a first polarity regression line derived from the logarithm of the measured value of the first polarity current within the first judgment time range during the first polarity charging and the logarithm of the measurement time of the first polarity current, and may detect the abnormality of the capacitor based on a second polarity regression line derived from the logarithm of the measured value of the second polarity current within the second judgment time range during the second polarity charging and the logarithm of the measurement time of the second polarity current.

[0016] Another embodiment of the present invention relates to an inspection method, which includes: a process of applying a voltage to a capacitor to charge it; a process of continuously measuring the current of the capacitor being charged; and a process of detecting an abnormality of the capacitor based on a regression line derived from the logarithm of the measured value of the current within a determination time range during charging and the logarithm of the measurement time of the current.

[0017] Technical Effects

[0018] According to the present invention, abnormality of a capacitor can be detected with high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1A This is a schematic perspective view showing an example of an inspection system for electronic components.

[0020] Figure 1B yes Figure 1A Front view of the inspection system shown.

[0021] Figure 2 It is a diagram showing the configuration of an example of an inspection device.

[0022] Figure 3 This is a graph (antilog graph) showing an example of the measurement results of the leakage current of an electronic component (capacitor).

[0023] Figure 4 2 is a graph (double logarithmic graph) showing an example of the measurement result of the leakage current of the electronic component (capacitor), and is a graph for explaining the first abnormality detection method.

[0024] Figure 5 2 is a graph (double logarithmic graph) showing an example of the measurement result of the leakage current of the electronic component (capacitor), and is a graph for explaining the second abnormality detection method.

[0025] Figure 6 This is a double logarithmic graph of “charging time-measurement current” which is an example of general electrical characteristics of a capacitor.

[0026] Explanation of symbols

[0027] 10 inspection system, 10A structure, 10a inclined surface, 11 indexing table, 11a rotation axis, 12 pit, 13 inspection device, 14 electronic component discharge unit, 15 discharge path, 16 recovery device, 18 supply feeder, 19 electronic component supply unit, 30 probe unit, 31 probe, 32 compression spring, 33 probe base, 35 electrode unit, 36 electrode, 37 electrode base, 38 electrode heater, 40 probe fixture, 41a fixture body, 41b fixture body, 41c fixture body, 41d fixture body, 42a sheet, 4 2b sheet, 43 probe heater, 50 circuit, 51 voltage applying unit, 52 current measuring unit, 55 control unit, 60 indexing table cover, 61 first surface side cover, 62 second surface side cover, 63 third surface side cover, B1 upper limit, B2 lower limit, Lr regression line, Lr1 first regression line, Lr2 second regression line, Lr3 third regression line, P1 first stage, P2 second stage, P3 third stage, Tv judgment time range, Tv1 first judgment time range, Tv2 second judgment time range, Tv3 third judgment time range, W electronic component DETAILED DESCRIPTION

[0028] Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings.

[0029] The electronic component W to be inspected in the following description may be a capacitor itself or an electronic component having a capacitor as a component. In addition, the specific type of the capacitor to be inspected is not limited, and the following technology may also be applied to MLCC, tantalum capacitors or other common capacitors.

[0030] [Check system]

[0031] Figure 1A It is a schematic perspective view showing an example of an inspection system 10 for electronic components. Figure 1B yes Figure 1A The front view of the inspection system 10 is shown. Figure 1B For ease of understanding, it is omitted Figure 1A The diagram shows a part of the components shown (for example, the supply feeder 18, the electronic component supply unit 19, and the control unit 55).

[0032] Figure 1A and Figure 1B The inspection system 10 shown includes a structure 10A, an index table 11 provided on an inclined surface 10 a of the structure 10A, an inspection device 13 , an electronic component discharge unit 14 , a discharge path 15 , and a collection device 16 .

[0033] The indexing table 11 has a disk shape, is arranged to be intermittently rotatable around a rotation axis 11a, and has a plurality of recesses 12 for accommodating electronic components to be inspected. The plurality of recesses 12 form a plurality of rows (e.g., 16 rows) along the radial direction of the indexing table 11, and in each row, the plurality of recesses 12 are arranged at equal angles in the circumferential direction of the indexing table 11.

[0034] The indexing table 11 is covered from both the front side and the back side by the indexing table cover 60. The front side indexing table cover 60 includes a first front side cover 61, a second front side cover 62, and a third front side cover 63 which are arranged adjacent to each other with a gap therebetween. A plurality of electronic components to be inspected are supplied from the supply feeder 18 to the electronic component supply unit 19, and are supplied from the electronic component supply unit 19 via the indexing table cover 60 (at Figure 1A and Figure 1B In the example shown, the first surface side cover 61 is supplied to the recess 12.

[0035] The inspection device 13 performs electrical inspection of the electronic components housed in each recess 12. The inspection device 13 of this example can perform inspection of the electronic components in an environment of normal temperature (e.g., 5°C to 35°C), but can also perform electrical inspection while actively applying a heat load (e.g., a heat load of about 100 to 170°C) to each electronic component as described later. A specific configuration example of the inspection device 13 is described later (see Figure 2 ).

[0036] The electronic component discharge unit 14 discharges the electronic components after the electrical inspection by the inspection device 13 to the collection device 16 through the discharge path 15 using compressed air, for example. The collection device 16 has a plurality of collection boxes (in Figure 1A and Figure 1BIn the example shown, there are six collection bins). The electronic component discharge unit 14 delivers each electronic component from the pit 12 (indexing table 11) to the corresponding collection bin according to the results of the electrical inspection. The electronic component discharge unit 14 operates under the control of the control unit 55 so that the electronic components that are judged to be normal as a result of the electrical inspection and the electronic components that are judged to be abnormal are discharged to their respective collection bins. It should be noted that the electronic component discharge unit 14 can discharge the electronic components to their respective collection bins according to the type and / or degree of abnormality based on the results of the electrical inspection, and can also discharge the electronic components to their respective collection bins according to conditions other than the results of the electrical inspection.

[0037] According to the inspection system 10, the index table 11 is moved along the groove 12 in a state where the electronic components to be inspected are stored in each of the grooves 12. Figure 1A and Figure 1B The electronic components W in each pit 12 are gradually transported downstream by the clockwise intermittent rotation. The electronic components W in each pit 12 are subjected to electrical inspection by the inspection device 13 at the inspection position on the transport path, and are classified and recovered by the electronic component discharge unit 14, the discharge path 15 and the recovery device 16 according to the results of the inspection.

[0038] It should be noted that the above Figure 1A and Figure 1B The inspection system 10 shown can be implemented based on a known technique, and further detailed description of the configuration of the inspection system 10 is omitted. As an example, the inspection system 10 of this embodiment may be configured similarly to the device disclosed in Japanese Patent Application Laid-Open No. 2023-5282.

[0039] [Inspection device]

[0040] Figure 2 FIG. 1 is a diagram showing a configuration of an example of the inspection device 13. Figure 2 In FIG. 1 , some elements (such as the probe holder 40 and the electrode unit 35) are shown in cross section. Figure 2 The illustration of the transfer station 11 (including the pit 12) etc., but Figure 2 The electronic components W shown are housed in the corresponding pockets 12 and are intermittently stopped at inspection positions in the middle of being transported by the index table 11 .

[0041] Figure 2 The inspection device 13 shown includes a plurality of probe units 30 , a probe fixture 40 , and an electrode unit 35 .

[0042] The number of probe units 30 is not limited, but the number of probe units 30 corresponding to the number of electronic components W to be inspected simultaneously (for example, the number of pits 12 arranged in the radial direction of the indexing table 11) can be set. Each probe unit 30 has a probe 31, a compression spring 32 and a probe base 33. The probe 31, the compression spring 32 and the probe base 33 all include a conductor with high electrical conductivity, preferably with high thermal conductivity. The probe base 33 is electrically connected to the circuit 50. The compression spring 32 is located between the probe 31 and the probe base 33, and is electrically connected to the probe 31 and the probe base 33, respectively. The probe 31 is supported by the probe fixture 40 in a manner that it can partially protrude from the probe fixture 40 while being subjected to elastic force from the compression spring 32.

[0043] The probe fixture 40 supporting each probe unit 30 has a stacked structure including fixture bodies 41a, 41b, 41c, 41d, sheets 42a, 42b, and a probe heater 43. The sheet 42a is provided between the fixture bodies 41a and 41b, the probe heater 43 is provided between the fixture bodies 41b and 41c, and the sheet 42b is provided between the fixture bodies 41c and 41d.

[0044] The fixing body 41a, 41b, 41c, 41d has relatively low thermal conductivity and electrical conductivity, and is made of, for example, a machinable ceramic (Photoveel) material. On the other hand, the sheet 42a, 42b has relatively high thermal conductivity and electrical conductivity, and is made of, for example, a graphite material. The probe heater 43 is capable of generating heat under the control of the control unit 55, and is made of, for example, a rubber heater. The heat from the probe heater 43 is effectively transferred to each probe unit 30 (especially the probe 31) via the sheet 42a, 42b.

[0045] The electrode unit 35 has a stacked structure including an electrode 36, an electrode base 37, and an electrode heater 38. The electrode 36 is electrically connected to the circuit 50. The electrode base 37 supports the electrode 36. The electrode heater 38 is provided in a manner covered by the electrode base 37 on both sides, namely, the front side and the back side. The electrode heater 38 can generate heat under the control of the control unit 55, and is composed of, for example, a rubber heater. The heat from the electrode heater 38 is transferred to the electrode 36 via the electrode base 37. From the viewpoint of effectively heating the electrode 36 using the electrode heater 38, it is preferred that the electrode base 37 (especially the portion located between the electrode heater 38 and the electrode 36) is composed of a member having excellent heat conductivity.

[0046] The circuit 50 and each probe unit 30 (in Figure 2In the example shown, the probe base 33) and the electrode 36 are connected. During the period when the probe 31 is separated from the electronic component W as the inspection object, the probe unit 30, the electronic component W, the electrode unit 35 (especially the electrode 36) and the circuit 50 are formed as an open circuit as a whole. On the other hand, by clamping the electronic component W as the inspection object using the probe 31 and the electrode 36 so that the probe 31 and the electrode 36 are in contact with the electronic component W, a closed circuit including the probe unit 30, the electronic component W, the electrode unit 35 (especially the electrode 36) and the circuit 50 is formed.

[0047] The circuit 50 of this example functions as a voltage applying unit 51 that applies a voltage to the electronic component W (capacitor) to charge it under the control of the control unit 55, and functions as a current measuring unit 52 that can continuously measure the current of the electronic component W (capacitor) being charged. In particular, the circuit 50 (voltage applying unit 51) provided as a part of the inspection system 10 is configured to be able to apply a large electrical load to the electronic component W that is the inspection object. The magnitude of such an electrical load can be changed by the control unit 55 controlling the circuit 50 (voltage applying unit 51), for example, a DC voltage of several times (for example, 2.5 times) the rated voltage of the electronic component W can be applied to the electronic component W.

[0048] The control unit 55 functions as an abnormality detection unit that detects abnormality of each electronic component W (particularly, a capacitor) based on the measurement result of the circuit 50 (current measurement unit 52). A specific method example of abnormality detection of each electronic component W by the control unit 55 will be described later.

[0049] According to the inspection device 13, during the period when the index table 11 is intermittently stopped, each of the pits 12 (see Figure 1A ) is clamped by the electrode 36 and the corresponding probe 31. It should be noted that when the electronic component W is clamped by the electrode 36 and the probe 31, the electrode unit 35 and / or each probe unit 30 (further the probe fixture 40) can be moved by a device not shown in the figure in such a way that the electrode 36 and the probe 31 start to approach each other from a relatively separated state.

[0050] Then, the circuit 50 functioning as the voltage applying unit 51 applies a test voltage to the electronic component W held by the electrode 36 and the probe 31, and the circuit 50 functioning as the current measuring unit 52 measures a minute current (leakage current) flowing through the electronic component W. In this way, the leakage current of the electronic component W being charged is continuously measured, and the measurement result is transmitted from the circuit 50 to the control unit 55.

[0051] The continuous measurement of the leakage current of the electronic component W can be performed at any time interval, but from the viewpoint of improving the accuracy of determining whether the electronic component W has an abnormality, it is preferred to continuously measure the leakage current of the electronic component W at the shortest possible time interval. According to a conventional measuring device, the leakage current of the electronic component W is usually measured at a time interval of about 10 ms (milliseconds) to 100 ms. On the other hand, the inspection system 10 of the present embodiment can also continuously measure the leakage current of the electronic component W at a time interval shorter than 10 ms. By continuously measuring the leakage current of the electronic component W at a time interval of, for example, less than 5 ms (more preferably less than 1 ms), it is possible to detect with high accuracy the abnormality of the electronic component W that is difficult to detect in the normal measurement performed by a conventional measuring device.

[0052] It should be noted that, when measuring the electrical characteristics (leakage current characteristics) of the electronic component W in a state where a heat load is applied, the electrode heater 38 and / or the probe heater 43 are heated to a desired temperature under the control of the control unit 55. Thus, while the electrode 36 and / or the probe 31 are heated and the electrode 36 and the probe 31 are in contact with the electronic component W, voltage application and leakage current measurement can be performed on the electronic component W, and heating of the electronic component W (application of a heat load) can be performed.

[0053] The control unit 55 determines whether or not each electronic component W has an abnormality based on the measurement result of the leakage current of each electronic component W provided from the circuit 50 .

[0054] [Inspection method]

[0055] Figure 3 This is a graph (antilog graph) showing an example of the measurement results of the leakage current of the electronic component W (capacitor). Figure 3 The X-axis represents the elapsed time from the start of measurement (origin (O)), that is, the charging time (milliseconds (ms)), and the Y-axis represents the measured value of the leakage current of the electronic component W (ampere (A)).

[0056] exist Figure 3 2 shows the leakage current measurement results of normal electronic components excluding abnormalities (i.e., "qualified products") and the leakage current measurement results of electronic components with abnormalities (i.e., "defective products") when a constant DC voltage is applied to the electronic component W (capacitor) for charging.

[0057] The inventors of the present application have made a thorough study of the behavior of the electrical characteristics (especially the leakage current characteristics) of capacitors (such as MLCC) during charging, and have newly discovered that capacitors sometimes exhibit temporary abnormal behavior during charging (see Figure 3 symbol “Ab”).

[0058] Such abnormal behavior can be grasped by the change in the measured value of the leakage current of the capacitor, but the abnormal behavior is not necessarily constant, and sometimes the change is small. In addition, the inventor of the present application has newly discovered that there are capacitors that exhibit abnormal behavior for a period of time (e.g., tens of milliseconds to seconds) and then return to normal behavior, and thereafter behave like qualified products.

[0059] It should be noted that, in the existing inspection device that detects the abnormality of the capacitor based on the measured peak value of the leakage current, although it is suitable for detecting the abnormality of the leakage current suddenly increasing, it is not necessarily suitable for detecting the abnormality of the leakage current decreasing. In addition, for the capacitor whose insulation property is not deteriorated but has the abnormality of unstable leakage current for some reason, the existing inspection device may not be able to fully deal with it.

[0060] In addition, although the capacity of MLCC has been increasing in recent years, the ceramic layer of MLCC tends to become thinner as the capacity increases, making it difficult to apply high voltage to MLCC for screening inspection. Therefore, a technology for screening inspection with high reliability is sought while suppressing the applied voltage to MLCC (capacitor) to a low level.

[0061] For example, the device of Patent Document 1 detects a steep pulse-shaped abnormal current (leakage current) generated by a capacitor during charging. Although the device of Patent Document 1 is effective when the leakage current during charging exhibits a stable behavior, it is difficult to reliably detect the abnormal current when the leakage current changes drastically per unit time. In addition, the device of Patent Document 1 cannot detect an abnormality in which the leakage current of the capacitor decreases.

[0062] In addition, the device of Patent Document 2 determines the quality of the capacitor by drawing a curve that is convex in either the upward or downward direction based on an evaluation function determined by the measured current value of the capacitor and the standard screening current value. However, as also described in Patent Document 2 (see paragraph 0012), the device of Patent Document 2 treats the temporary change of the measured current value of the capacitor as noise and does not detect it as an abnormality. In addition, the device of Patent Document 1 cannot detect the abnormality of the capacitor's leakage current reduction.

[0063] As a result of the inventors' intensive research based on the above insights, they have discovered a new technology that can effectively and accurately detect capacitor anomalies that cannot be detected in existing devices. That is, a new method for accurately detecting capacitor anomalies has been discovered based on a regression line derived from the logarithm of the measured value of the current (leakage current) of the electronic component W within the judgment time range during the charging of the electronic component W (capacitor) and the logarithm of the measurement time of the current. According to this method, it is possible to accurately detect abnormal behavior temporarily exhibited by an abnormal capacitor during charging. In particular, even if the change in abnormal behavior is small, or even if the abnormal behavior only lasts for a limited time (e.g., tens of milliseconds to a few seconds), such abnormal behavior can be detected with high accuracy.

[0064] Although various variations of such anomaly detection methods are conceivable, any anomaly detection method can detect abnormal behavior of a capacitor based on a regression line. Although a typical example of such anomaly detection method is shown below, an abnormality detection method that uses a regression line in a manner different from the typical example described below is also included in the content of the present invention.

[0065] [First Abnormality Detection Method]

[0066] Figure 4 2 is a graph (double logarithmic graph) showing an example of the measurement result of the leakage current of the electronic component W, and is a graph for explaining the first abnormality detection method. Figure 4 The X-axis and Y-axis are based on logarithmic scales, Figure 4 The X-axis logarithmically shows the elapsed time from the start of measurement (origin (O)), that is, the charging time (milliseconds), and the Y-axis logarithmically shows the measured value of the leakage current of the electronic component W (amperes).

[0067] exist Figure 4 The leakage current measurement results of normal electronic components excluding abnormalities (i.e., "qualified products") and the leakage current measurement results of electronic components with abnormalities (i.e., "defective products") are shown in FIG. 1 . In addition, in FIG. 1 , a constant DC voltage is applied to the electronic component W (capacitor) to charge the electronic component W (capacitor). Figure 4 The “regression line Lr” obtained based on the least square method from the measurement results of conforming products and defective products is shown.

[0068] According to the inspection method based on the first abnormality detection method, the charging process, the current measurement process, and the abnormality detection process are performed under the control of the control unit 55 .

[0069] During the charging process, the electronic component W (capacitor) is Figure 2In the state where the probe 31 and the electrode 36 are clamped, charging is performed by applying a voltage by the circuit 50 (voltage applying unit 51). In the current measuring step, the current (leakage current of the capacitor) of the electronic component W being charged is continuously measured by the circuit 50 (current measuring unit 52). In this way, the current measuring step and the charging step are performed in parallel.

[0070] Then, in the abnormality detection step, the control unit 55 (abnormality detection unit) detects abnormality of the electronic component W (capacitor) based on the regression line Lr derived from the logarithm of the leakage current measurement value and the logarithm of the leakage current measurement time within the determination time range Tv during charging. More specifically, the control unit 55 detects abnormality of the electronic component W based on the consistency of the logarithm of the leakage current measurement value and the logarithm of the measurement time with respect to the regression line Lr.

[0071] The "judgment time range Tv" mentioned here is a time range suitable for judging whether the electronic component W has an abnormality. Specifically, it is set to a time range in which the consistency of the measurement results of qualified products with respect to the regression line Lr is high. The optimal judgment time range Tv is determined by the leakage current characteristics of the electronic component W and / or the influence of the applied voltage on the electronic component W. As an example, it can also be set to the start of charging (see Figure 4 The time range is 200ms to 1500ms after the origin "O").

[0072] The consistency of the logarithm of the leakage current measurement value and the logarithm of the measurement time with respect to the regression line Lr is usually calculated as a coefficient of determination based on the least squares method. The specific calculation method of the coefficient of determination is not limited, and the coefficient of determination can be calculated using a known calculation formula.

[0073] For example, when the electronic component W is a qualified product, the "consistency of the logarithm of the measured value of the leakage current and the logarithm of the measurement time with respect to the regression line Lr" becomes relatively high, and the value of the determination coefficient (contribution rate) based on the least square method also becomes relatively large. When the determination coefficient of the case where the logarithm of the measured value of the leakage current and the logarithm of the measurement time completely agree with the regression line Lr is expressed as "100%", the determination coefficient of the qualified electronic component W can be shown as 95.0% or more (as an example, 99.0% or more).

[0074] On the other hand, when the electronic component W is a defective product, the "consistency of the logarithm of the measured value of the leakage current and the logarithm of the measurement time with respect to the regression line Lr" becomes relatively low, and the value of the determination coefficient also becomes relatively small, for example, a value less than 95.0% can be shown (as an example, a value less than 99.0%).

[0075] As described above, the electronic components W to be inspected can be classified as conforming products or defective products based on the determination coefficient, but the threshold value of the determination coefficient that serves as the classification standard for conforming products and defective products is appropriately set according to the actual tolerance of abnormalities. That is, the closer the threshold value is to "100%", the stricter the determination of the presence or absence of abnormalities becomes, and even slight abnormalities are not allowed, resulting in a tendency that the proportion of electronic components W judged as defective products increases.

[0076] Therefore, the higher the reliability requirement for the normality of the electrical characteristics (leakage current characteristics) of the electronic component W, the closer the threshold of the determination coefficient that becomes the classification standard for qualified products and unqualified products is set to a value close to "100%". In order to meet the high reliability required in advanced technology in recent years, it is sometimes required that the threshold of the determination coefficient be set to a value such as "99.0%" or above.

[0077] In this way, "the consistency of the logarithm of the measured value of the leakage current and the logarithm of the measurement time with respect to the regression line Lr" indicates the linearity of the logarithm of the measured value of the leakage current and the logarithm of the measurement time, and can be expressed as a coefficient of determination based on the least squares method. However, "the consistency of the logarithm of the measured value of the leakage current and the logarithm of the measurement time with respect to the regression line Lr" can also be obtained based on any other method that can directly or indirectly evaluate the linearity on the double logarithmic graph of "charging time-measured current".

[0078] For example, the control unit 55 (abnormality detection unit) may also use any method to find the "inconsistency" between the logarithm of the leakage current measurement value and the logarithm of the measurement time with respect to the regression line Lr, and detect the abnormality of the electronic component W based on the inconsistency. In addition, the control unit 55 (abnormality detection unit) may extract the data of the leakage current measurement value of the electronic component W as the inspection object only for a part of the time range (determination time range Tv) in the charging time. In this case, the control unit 55 may also detect the abnormality of the electronic component W based on the regression line Lr derived from the extracted logarithm of the leakage current measurement value and the logarithm of the leakage current measurement time.

[0079] The control unit 55 controls the electronic component discharge unit 14 based on the inspection results including the above series of steps to discharge the electronic components W determined to have abnormalities and the electronic components W determined not to have abnormalities to the respective collection boxes of the collection device 16 via the discharge path 15 .

[0080] [Second abnormality detection method]

[0081] In the following description related to the second abnormality detection method, the first abnormality detection method (see Figure 4 )The detailed description of the same processing is omitted.

[0082] Figure 5 2 is a graph (double logarithmic graph) showing an example of the measurement result of the leakage current of the electronic component W, and is a graph for explaining the second abnormality detection method. Figure 5 The X-axis and Y-axis are represented using logarithmic scales. Figure 5 The X-axis logarithmically shows the elapsed time from the start of measurement (origin (O)), that is, the charging time (milliseconds), and the Y-axis logarithmically shows the measured value of the leakage current of the electronic component W (amperes).

[0083] exist Figure 5 The measurement results of the electronic components as qualified products and the measurement results of the electronic components as defective products are shown in FIG, and the regression line Lr obtained based on the measurement results of qualified products and defective products is shown. Figure 5 The upper limit B1 and the lower limit B2 of the allowable current range are shown in FIG.

[0084] The inspection method based on the second abnormality detection method also performs a charging step, a current measuring step, and an abnormality detection step. In particular, the charging step and the current measuring step are performed in the same manner as the inspection method based on the first abnormality detection method described above.

[0085] However, in the abnormality detection process based on the second abnormality detection method, the control unit 55 (abnormality detection unit) determines whether the logarithm of the measured value of the leakage current of the electronic component W within the determination time range Tv is included in the current allowable range determined based on the regression line Lr. That is, the abnormality of the electronic component W (capacitor) is detected based on the relationship between the logarithm of the measured value of the leakage current and at least one of the upper limit B1 and the lower limit B2 of the current allowable range determined based on the regression line Lr over the determination time range Tv.

[0086] exist Figure 5 In the double logarithmic graph, the area between the line indicated by the symbol "B1" (upper limit) and the line indicated by the symbol "B2" (lower limit) corresponds to the allowable current range, and the regression line Lr exists in this area (allowable current range) within the judgment time range Tv.

[0087] As described above, the electronic component W to be inspected can be classified as a qualified product or a defective product based on the current allowable range (upper limit B1 and lower limit B2), but the upper limit B1 and lower limit B2 of the current allowable range are determined to be threshold values ​​that are equivalent to the classification criteria for qualified products and defective products, and are appropriately set according to the actual tolerance of abnormalities. That is, the closer the upper limit B1 and lower limit B2 of the current allowable range are to the regression line Lr, the stricter the determination of the presence or absence of abnormalities becomes, and even slight abnormalities are not allowed, which tends to increase the proportion of electronic components W being judged as defective products. Therefore, the higher the reliability requirement for the normal degree of the electrical characteristics (leakage current characteristics) of the electronic component W, the closer the upper limit B1 and lower limit B2 of the current allowable range that are the classification criteria for qualified products and defective products are set to the regression line Lr.

[0088] The specific method for determining the upper limit B1 and the lower limit B2 of the current allowable range is not limited. For example, between the upper limit B1 and the lower limit B2 of the current allowable range, the measured current (see Figure 5 The difference between the regression line Lr and the upper limit B1 or lower limit B2 of the current allowable range in the entire determination time range Tv may be the same or different. Therefore, in the double logarithmic graph of "charging time-measured current" (refer to Figure 5 ), the line indicating the upper limit B1 of the allowable current range and the line indicating the lower limit B2 may be parallel to the regression line Lr or may not be parallel to the regression line Lr.

[0089] In addition, the upper limit B1 and lower limit B2 of the current allowable range can also be determined based on the values ​​of the regression line Lr (the values ​​of the Y axis related to the measured current) at multiple discrete time points selected from the determination time range Tv. For example, regarding the two points of the "starting time point (starting point)" and the "ending time point (end point)" of the determination time range Tv, the upper limit B1 and lower limit B2 of the current allowable range can also be determined based on the regression line Lr. In this case, in the double logarithmic graph of "charging time-measured current" (refer to Figure 5 ), the upper limit B1 of the current allowable range over the entire determination time range Tv can also be determined by a straight line passing through the two points (starting point and end point) related to the upper limit B1 of the current allowable range. Similarly, in the double logarithmic graph of "charging time-measured current", the lower limit B2 of the current allowable range over the entire determination time range Tv can also be determined by a straight line passing through the two points (starting point and end point) related to the lower limit B2 of the current allowable range.

[0090] In addition, the control unit 55 (abnormality detection unit) may set only one of the upper limit B1 and the lower limit B2 of the current allowable range to a value different from the regression line Lr. In this case, the other of the upper limit B1 and the lower limit B2 of the current allowable range may be set to the same value as the regression line Lr.

[0091] In the above-mentioned abnormality detection process, when the entire measured current of the electronic component W within the determination time range Tv is within the current allowable range (for example, including the boundaries (upper limit B1 and lower limit B2)), the control unit 55 can determine that there is no abnormality in the electronic component W. On the other hand, when at least a part of the measured current of the electronic component W within the determination time range Tv is outside the current allowable range (for example, excluding the boundaries (upper limit B1 and lower limit B2)), it can be determined that the electronic component W has an abnormality.

[0092] Then, the control unit 55 controls the electronic component discharge unit 14 based on the inspection results including the above series of steps, and discharges the electronic components W determined to have abnormalities and the electronic components W not determined to have abnormalities to the respective collection boxes of the collection device 16 through the discharge path 15.

[0093] [Application example of anomaly detection method]

[0094] Regarding the first abnormality detection method and the second abnormality detection method (refer to Figure 4 and Figure 5 ) or other detection methods based on the regression line Lr, by applying the inspection method of the electronic component W as described below, it is possible to detect abnormalities in the electronic component W with high accuracy.

[0095] [Application Example 1]

[0096] Figure 6 This is a double logarithmic graph of “charging time-measurement current” which is an example of general electrical characteristics of a capacitor.

[0097] When a constant DC voltage is applied to a capacitor to charge it, the relationship between the logarithm of the capacitor charging time and the logarithm of the leakage current is not necessarily constant over the entire charging time, and there are multiple stages showing inherent linearity (proportional relationship) (see Figure 6 "P1" to "P3"). Figure 6 In the example shown, there is a first stage P1 in which the leakage current of the capacitor is almost constant, a second stage P2 in which the leakage current sharply decreases, and a third stage P3 in which the leakage current sharply decreases compared to the first stage P1 but more gently than the second stage P2. Figure 6In the double logarithmic graph shown, "charging time - measured current" shows a proportional relationship in any stage from the first stage P1 to the third stage P3, but the ratio of the proportional relationship of "charging time - measured current" (i.e., the slope of the regression line) is different between the first stage P1 to the third stage P3.

[0098] The control unit 55 (abnormality detection unit) can detect abnormality of the electronic component W (capacitor) at each stage by setting the determination time range Tv and the regression line Lr at each stage.

[0099] That is, the control unit 55 can detect the abnormality of the electronic component W within the first determination time range during charging based on the first regression line derived from the logarithm of the leakage current measurement value of the electronic component W within the first determination time range during charging and the logarithm of the leakage current measurement time. On the other hand, the control unit 55 can detect the abnormality of the electronic component W within the second determination time range during charging based on the second regression line derived from the logarithm of the leakage current measurement value of the electronic component W within the second determination time range during charging and the logarithm of the leakage current measurement time.

[0100] By setting the "first determination time range" and the "second determination time range" here to different stages (see Figure 6 The first stage P1, the second stage P2 and the third stage P3) can detect the abnormality of each electronic component W in multiple stages. It should be noted that when there are more than three stages in the relationship between the charging time of the capacitor and the leakage current, it can be set to allocate more than three determination time ranges to each stage.

[0101] For example, Figure 6 In the example shown, the "first judgment time range Tv1" can be set in the first stage P1, the "second judgment time range Tv2" can be set in the second stage P2, and the "third judgment time range Tv3" can be set in the third stage P3. In this case, the first regression line Lr1 is determined based on the measurement result of the leakage current in the first judgment time range Tv1, the second regression line Lr2 is determined based on the measurement result of the leakage current in the second judgment time range Tv2, and the third regression line Lr3 is determined based on the measurement result of the leakage current in the third judgment time range Tv3. And, using the above-mentioned abnormality detection method (refer to Figure 4 and Figure 5 ), it is capable of detecting the abnormality of the electronic component W within the first determination time range Tv1 based on the first regression line Lr1, it is capable of detecting the abnormality of the electronic component W within the second determination time range Tv2 based on the second regression line Lr2, and it is capable of detecting the abnormality of the electronic component W within the third determination time range Tv3 based on the third regression line Lr3.

[0102] It should be noted that the "first determination time range" and the "second determination time range" can be set at a common stage. For example, it can be set at a certain stage that occupies a longer time range (refer to Figure 6 In the third stage P3), the "first judgment time range" and the "second judgment time range" (as well as the judgment time ranges after the third) are set.

[0103] [Application Example 2]

[0104] The inspection device 13 can perform multiple electrical inspections on each electronic component W. Such multiple electrical inspections can include two electrical inspections in which the polarities (positive and negative directions) of the current (DC current) applied to each electronic component W when the inspection voltage is applied are different from each other.

[0105] That is, the circuit 50 (voltage applying section 51; see Figure 2 ) can apply a voltage to the electronic component W (capacitor) with a first polarity to charge the first polarity, and after the first polarity charging, apply a voltage to the electronic component W with a second polarity opposite to the first polarity to charge the second polarity. In this case, the circuit 50 (current measuring unit 52) ​​measures the leakage current of the electronic component W during the first polarity charging, that is, the first polarity current, and measures the leakage current of the electronic component W during the second polarity charging, that is, the second polarity current. In addition, the control unit 55 (abnormality detection unit) can detect the abnormality of the electronic component W (capacitor) based on the first polarity regression line derived from the logarithm of the measured value of the first polarity current within the first determination time range during the first polarity charging and the logarithm of the measurement time of the first polarity current. Similarly, the control unit 55 can detect the abnormality of the electronic component W (capacitor) based on the second polarity regression line derived from the logarithm of the measured value of the second polarity current within the second determination time range during the second polarity charging and the logarithm of the measurement time of the second polarity current. It should be noted that since the measured value of the leakage current (e.g., the second polarity current) of the electronic component W also becomes a negative value when a negative voltage is applied to the electronic component W (e.g., the second polarity is charged), the regression line can also be derived from the logarithm of the absolute value of the measured value of the leakage current.

[0106] The capacitor of the electronic component W sometimes exhibits unique electrical characteristics depending on the polarity of the applied current, and sometimes exhibits abnormal behavior of leakage current only in one of the cases where the voltage of the first polarity is applied and the case where the voltage of the second polarity is applied. Even if the electronic component W to be inspected has such polarity, the abnormality of the electronic component W can be reliably detected by performing electrical inspections in relation to the first polarity and the second polarity, respectively, as in this application example.

[0107] As described above, according to the above-mentioned inspection device 13 and inspection method, it is possible to detect abnormalities in the electronic component W (capacitor) based on the regression line Lr derived from the logarithm of the measured value of the leakage current of the electronic component W within the determination time range Tv during charging and the logarithm of the measurement time of the leakage current.

[0108] In particular, even when an abnormal electronic component W exhibits abnormal behavior only temporarily during charging, the above-mentioned inspection device 13 and inspection method can appropriately detect the abnormality of such an electronic component W. In addition, even when the behavior of the leakage current of the electronic component W is not constant and the amount of change in the leakage current is small, the above-mentioned inspection device 13 and inspection method can appropriately detect the abnormality of such an electronic component W.

[0109] In addition, according to the above-mentioned inspection device 13 and inspection method, it is possible to detect not only an abnormality of increased leakage current of the electronic component W, but also an abnormality of decreased leakage current. In addition, even if the inspection voltage applied to the electronic component W as the inspection object is low, the abnormality of the electronic component W can be detected with good reliability.

[0110] In addition, although there are cases where an electronic component W whose leakage current per unit time fluctuates violently even in a normal state is used as an inspection object, according to the above-mentioned second abnormality detection method (see Figure 5 ), it is also possible to detect such anomalies of the electronic component W with high accuracy. That is, by determining the upper limit B1 and / or lower limit B2 of the current allowable range in consideration of the magnitude of the fluctuation of the leakage current in the normal state of the electronic component W, it is possible to detect the true "abnormality" of the electronic component W while preventing the fluctuation of the leakage current in the normal state from being detected as "abnormality". In addition, according to such a second abnormality detection method, it is also possible to detect "abnormality in which the insulation of the electronic component W (capacitor) is not deteriorated but the leakage current is unstable for some reason".

[0111] It should be noted that the embodiments and modifications disclosed in this specification are merely examples in all respects and are not to be interpreted as limiting. The above-mentioned embodiments and modifications can be omitted, replaced, and changed in various ways without departing from the attached claims and their subject matter. For example, the above-mentioned embodiments and modifications can be combined in whole or in part, and embodiments other than the above-mentioned can also be combined with the above-mentioned embodiments or modifications. In addition, the effects of the present invention described in this specification are merely examples, and other effects can also be provided.

[0112] The technical category for realizing the above technical idea is not limited. For example, the above technical idea can also be realized by a computer program for causing a computer to execute one or more sequences (steps) included in the method for manufacturing the above device or the method for using the above device. In addition, the above technical idea can also be realized by a computer-readable non-transitory recording medium that records such a computer program.

Claims

1. An inspection device, characterized in that: have: a voltage applying unit that applies a voltage to the capacitor to charge it; a current measuring unit configured to continuously measure the current of the capacitor being charged; as well as The abnormality detection unit detects abnormality of the capacitor based on a regression line derived from a logarithm of the current measurement value and a logarithm of the current measurement time within a determination time range during the charging.

2. The inspection device according to claim 1, characterized in that: The abnormality detection unit detects an abnormality of the capacitor based on the consistency of the logarithm of the measured value of the current and the logarithm of the measurement time with respect to the regression line.

3. The inspection device according to claim 1 or 2, characterized in that: The abnormality detection unit detects abnormality of the capacitor based on a relationship between a logarithm of the current measurement value and at least one of an upper limit and a lower limit of a current allowable range determined based on the regression line over the determination time range.

4. The inspection device according to claim 1 or 2, characterized in that: The abnormality detection unit detects an abnormality of the capacitor based on a first regression line derived from a logarithm of the current measurement value and a logarithm of the current measurement time within a first determination time range during the charging. The abnormality detection unit detects an abnormality of the capacitor based on a second regression line derived from a logarithm of the current measurement value and a logarithm of the current measurement time within a second determination time range during the charging.

5. The inspection device according to claim 1 or 2, characterized in that: The voltage applying unit applies a voltage with a first polarity to the capacitor to charge the capacitor with a first polarity. The voltage applying unit applies a voltage to the capacitor with a second polarity opposite to the first polarity after charging with the first polarity to perform second polarity charging, The current measuring unit measures a first polarity current, which is a current flowing through the capacitor during charging of the first polarity. The current measuring unit measures a second polarity current, which is a current flowing through the capacitor during charging of the second polarity. The abnormality detection unit detects an abnormality of the capacitor based on a first polarity regression line derived from a logarithm of a measured value of the first polarity current within a first determination time range in the first polarity charging and a logarithm of a measurement time of the first polarity current. The abnormality detection unit detects abnormality of the capacitor based on a second polarity regression line derived from a logarithm of a measurement value of the second polarity current within a second determination time range during the second polarity charging and a logarithm of a measurement time of the second polarity current.

6. An inspection method, characterized in that: include: The process of applying voltage to a capacitor to charge it; The step of continuously measuring the current of the capacitor during charging; as well as A step of detecting an abnormality of the capacitor based on a regression line derived from a logarithm of the current measurement value and a logarithm of the current measurement time within a determination time range during the charging.

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