Inspection device and inspection method

Abstract

To provide an inspection device and an inspection method advantageous for accurately detecting an abnormality in a capacitor.SOLUTION: An inspection device includes: a voltage application unit which applies a voltage to a capacitor to charge the capacitor; a current measurement unit which continuously measures a current of the capacitor during charging; and an abnormality detection unit which detects an abnormality in the capacitor on the basis of a regression line Lr derived from a logarithm of a measurement value of the current within a determination time range during charging and a logarithm of measurement timing of the current.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to an inspection device and an inspection method for detecting an abnormality in a capacitor. [Background technology]

[0002] Capacitors such as MLCCs (Multi-Layer Ceramic Capacitors) and electronic components that include capacitors are usually shipped after undergoing inspection to detect defective products. In recent years, in particular, many MLCCs have come to be used in devices such as automobiles and communication devices that require high performance and safety, and there is a demand for inspections that can guarantee a higher level of reliability for large quantities of MLCCs.

[0003] Regarding such inspections, for example, Patent Document 1 discloses a defect detection device that aims to quickly detect and screen internal defects such as foreign matter and pinholes in multilayer ceramic capacitors, while Patent Document 2 discloses a quality determination method that aims to quickly determine whether a capacitor is good or bad. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 09-152455 [Patent Document 2] JP 2000-228337 A Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure has been made in consideration of the above-mentioned circumstances, and has an object to provide a technique that is advantageous for detecting an abnormality in a capacitor with high accuracy. [Means for solving the problem]

[0006] One aspect of the present disclosure relates to an inspection device that includes a voltage application unit that applies a voltage to a capacitor to charge it, 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 based on a regression line derived from the logarithm of the measured current value in a determination time range during charging and the logarithm of the timing of measuring the current.

[0007] The abnormality detection unit may detect an abnormality in the capacitor based on the degree of agreement between the logarithm of the measured current value and the logarithm of the measurement timing with respect to the regression line.

[0008] The abnormality detection unit may detect an abnormality in the capacitor based on a logarithmic relationship of the measured current value with respect to at least one of an upper limit and a lower limit of an allowable current range defined based on a regression line over a determination time range.

[0009] The abnormality detection unit may detect an abnormality in the capacitor based on a first regression line derived from the logarithm of the measured current value in a first judgment time range during charging and the logarithm of the timing of measuring the current, and may detect an abnormality in the capacitor based on a second regression line derived from the logarithm of the measured current value in a second judgment time range during charging and the logarithm of the timing of measuring the current.

[0010] The voltage application unit may perform first polarity charging by applying a voltage to the capacitor with a first polarity, or may perform second polarity charging by applying a voltage to the capacitor with a second polarity that is opposite to the first polarity after the first polarity charging, the current measurement unit may measure a first polarity current that is the current through the capacitor during first polarity charging, and may measure a second polarity current that is the current through the capacitor during second polarity charging, the abnormality detection unit may detect an abnormality in the capacitor based on a first polarity regression line derived from the logarithm of the measured value of the first polarity current in a first judgment time range during first polarity charging and the logarithm of the measurement timing of the first polarity current, or may detect an abnormality in the capacitor based on a second polarity regression line derived from the logarithm of the measured value of the second polarity current in a second judgment time range during second polarity charging and the logarithm of the measurement timing of the second polarity current.

[0011] Another aspect of the present disclosure relates to an inspection method including the steps of applying a voltage to a capacitor to charge it, continuously measuring a current through the capacitor during charging, and detecting an abnormality in the capacitor based on a regression line derived from the logarithm of the measured current value in a determination time range during charging and the logarithm of the timing of measuring the current. Effect of the Invention

[0012] According to the present disclosure, an abnormality in a capacitor can be detected with high accuracy. [Brief description of the drawings]

[0013] [Figure 1A] FIG. 1A is a perspective view showing an outline of an example of an inspection system for electronic components. [Figure 1B] FIG. 1B is a front view of the inspection system shown in FIG. 1A. [Diagram 2] FIG. 2 is a diagram illustrating a configuration of an example of an inspection device. [Diagram 3] FIG. 3 is a graph (antilogarithm graph) showing an example of the measurement results of leakage current of an electronic component (capacitor). [Figure 4] FIG. 4 is a graph (log-log graph) showing an example of the measurement results of leakage current of an electronic component (capacitor), and is a graph for explaining the first abnormality detection technique. [Diagram 5] FIG. 5 is a graph (log-log graph) showing an example of the measurement results of leakage current of an electronic component (capacitor), and is a graph for explaining the second abnormality detection technique. [Figure 6] FIG. 6 is a log-log graph of "charging time vs. measured current" showing an example of typical electrical characteristics of a capacitor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings.

[0015] In the following description, the electronic component W to be inspected may be a capacitor itself, or may be an electronic component that includes a capacitor as a component. The specific type of capacitor to be inspected is not limited, and the following technology may be applied to MLCCs, tantalum capacitors, or other general capacitors.

[0016] [Inspection system] Fig. 1A is a perspective view showing an outline of an example of an electronic component inspection system 10. Fig. 1B is a front view of the inspection system 10 shown in Fig. 1A. Note that in Fig. 1B, in order to facilitate understanding, some of the components shown in Fig. 1A (e.g., supply feeder 18, electronic component supply unit 19, and control unit 55) are omitted from illustration.

[0017] An inspection system 10 shown in FIGS. 1A and 1B includes a structure 10A, an index table 11 provided on an inclined surface 10a of the structure 10A, an inspection device 13, an electronic component ejection section 14, an ejection path 15, and a recovery device 16.

[0018] Index table 11 has a disk shape, is provided so as to be intermittently rotatable about rotation axis 11a, and has a large number of pockets 12 for accommodating electronic components to be inspected. The large number of pockets 12 form a plurality of rows (e.g., 16 rows) in the radial direction of index table 11, and in each row, a plurality of pockets 12 are arranged at equal angular intervals in the circumferential direction of index table 11.

[0019] The index table 11 is covered from both the front and back sides by index table covers 60. The front side index table cover 60 includes a first front cover 61, a second front cover 62, and a third front cover 63 arranged adjacent to each other with gaps between them. A large number of electronic components to be inspected are supplied from the supply feeder 18 to the electronic component supply unit 19, and then supplied from the electronic component supply unit 19 to the pocket 12 via the index table cover 60 (first front cover 61 in the example shown in FIGS. 1A and 1B).

[0020] The inspection device 13 performs electrical inspection of the electronic components housed in each pocket 12. The inspection device 13 of this example can inspect the electronic components in a room temperature environment (e.g., 5°C to 35°C), but can also perform electrical inspection while actively applying a thermal load (e.g., a thermal load of about 100°C to 170°C) to each electronic component, as described later. A specific configuration example of the inspection device 13 will be described later (see FIG. 2).

[0021] The electronic component ejection unit 14 ejects the electronic components after the electrical inspection by the inspection device 13 to the collection device 16 via the ejection path 15, for example, by using compressed air. The collection device 16 has a plurality of collection boxes (six collection boxes in the example shown in FIG. 1A and FIG. 1B). The electronic component ejection unit 14 sends each electronic component from the pocket 12 (index table 11) to the corresponding collection box according to the result of the electrical inspection. The electronic component ejection unit 14 operates under the control of the control unit 55 so that electronic components determined to be normal and electronic components determined to have an abnormality as a result of the electrical inspection are ejected into different collection boxes. The electronic component ejection unit 14 may eject the electronic components into different collection boxes according to the type and degree of abnormality based on the result of the electrical inspection, or may eject the electronic components into different collection boxes according to conditions other than the result of the electrical inspection.

[0022] 1A and 1B while electronic components to be inspected are stored in each pocket 12, the index table 11 is intermittently rotated in the clockwise direction in FIG. 1A and FIG. 1B, so that the electronic components W in each pocket 12 are gradually transported downstream. The electronic components W in each pocket 12 are electrically inspected by the inspection device 13 at an inspection position on the transport path, and are sorted and collected by the electronic component ejection section 14, the ejection path 15 and the collection device 16 according to the results of the inspection.

[0023] 1A and 1B can be realized based on known technology, and further specific description of the configuration of the inspection system 10 is omitted. The inspection system 10 of the present embodiment may be configured similarly to the device disclosed in JP 2023-5282 A, for example.

[0024] [Inspection equipment] Fig. 2 is a diagram showing an example of the configuration of the inspection device 13. In Fig. 2, some elements (for example, the probe holder 40 and the electrode unit 35) are shown in cross section. Also, although the index table 11 (including the pockets 12) and the like are omitted in Fig. 2, each electronic component W shown in Fig. 2 is accommodated in a corresponding pocket 12 and is in a state of being intermittently stopped at an inspection position during transportation by the index table 11.

[0025] The testing device 13 shown in FIG. 2 includes a plurality of probe units 30, a probe holder 40, and an electrode unit 35.

[0026] The number of probe units 30 is not limited, but the number of probe units 30 is set to correspond to the number of electronic components W to be simultaneously inspected (for example, the number of pockets 12 arranged in the radial direction of the index table 11). 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 an electric conductor having high electrical conductivity, and preferably have high thermal conductivity. The probe base 33 is electrically connected to the electric circuit 50. The compression spring 32 is located between the probe 31 and the probe base 33, and is electrically connected to each of the probe 31 and the probe base 33. The probe 31 is supported by the probe holder 40 so as to partially protrude from the probe holder 40 while receiving an elastic force from the compression spring 32 and to be able to advance and retreat from the probe holder 40.

[0027] The probe holder 40 supporting each probe unit 30 has a laminated structure including holder bodies 41a, 41b, 41c, and 41d, sheet materials 42a and 42b, and a probe heater 43. The sheet material 42a is provided between the holder body 41a and the holder body 41b, the probe heater 43 is provided between the holder body 41b and the holder body 41c, and the sheet material 42b is provided between the holder body 41c and the holder body 41d.

[0028] The holder bodies 41a, 41b, 41c, and 41d have relatively low thermal conductivity and electrical conductivity and are made of, for example, a photovoltaic material. On the other hand, the sheet materials 42a and 42b have relatively high thermal conductivity and electrical conductivity and are 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. Heat from the probe heater 43 is efficiently transferred to each probe unit 30 (particularly the probe 31) via the sheet materials 42a and 42b.

[0029] The electrode unit 35 has a laminated structure including an electrode 36, an electrode base 37, and an electrode heater 38. The electrode 36 is electrically connected to an electric circuit 50. The electrode base 37 supports the electrode 36. The electrode heater 38 is provided so as to be covered by the electrode base 37 on both the front and back sides, is capable of generating heat under the control of the control unit 55, and is constituted, for example, by a rubber heater. Heat from the electrode heater 38 is transferred to the electrode 36 via the electrode base 37. From the viewpoint of efficiently heating the electrode 36 by the electrode heater 38, it is preferable that the electrode base 37 (particularly the portion located between the electrode heater 38 and the electrode 36) is constituted by a material having excellent heat conductivity.

[0030] The electric circuit 50 is connected to each probe unit 30 (probe base 33 in the example shown in FIG. 2) and electrode 36. While the probe 31 is away from the electronic component W to be inspected, the probe unit 30, the electronic component W, the electrode unit 35 (particularly the electrode 36), and the electric circuit 50 as a whole form an open circuit configuration. On the other hand, the electronic component W to be inspected is sandwiched between the probe 31 and the electrode 36 and the probe 31 and the electrode 36 come into contact with the electronic component W, thereby forming a closed circuit including the probe unit 30, the electronic component W, the electrode unit 35 (particularly the electrode 36), and the electric circuit 50.

[0031] The electric circuit 50 in this example functions as a voltage application unit 51 that applies a voltage to the electronic component W (capacitor) to charge it under the control of the control unit 55, and also functions as a current measurement unit 52 that can continuously measure the current of the electronic component W (capacitor) during charging. In particular, the electric circuit 50 (voltage application unit 51) provided as part of the inspection system 10 is configured to be able to apply a relatively large electric load to the electronic component W to be inspected. The magnitude of such an electric load can be changed by the control unit 55 controlling the electric circuit 50 (voltage application unit 51), and for example, a DC voltage of about several times (e.g., 2.5 times) the rated voltage of the electronic component W may be applied to the electronic component W.

[0032] The control unit 55 functions as an abnormality detection unit that detects abnormality in each electronic component W (particularly, a capacitor) based on the measurement result of the electric circuit 50 (current measurement unit 52). A specific example of a method for detecting an abnormality in each electronic component W by the control unit 55 will be described later.

[0033] According to the above-described inspection device 13, while the index table 11 is stopped intermittently, the electronic component W in each pocket 12 (see FIG. 1A) located at the inspection position is sandwiched between the electrodes 36 and the corresponding probes 31. When the electronic component W is sandwiched between the electrodes 36 and the probes 31, the electrode unit 35 and / or each probe unit 30 (and thus the probe holder 40) may be moved by a device not shown so that the electrodes 36 and the probes 31 are brought closer to each other from a state in which they are relatively separated from each other.

[0034] An inspection voltage is applied to the electronic component W sandwiched between the electrodes 36 and the probes 31 by the electric circuit 50 functioning as a voltage application unit 51, and a minute current (leakage current) flowing through the electronic component W is measured by the electric circuit 50 functioning as a current measurement unit 52. In this way, the leakage current of the electronic component W being charged is continuously measured, and the measurement result is sent from the electric circuit 50 to the control unit 55.

[0035] Although continuous measurement of the leakage current of the electronic component W can be performed at any time interval, from the viewpoint of increasing the accuracy of judging whether or not there is an abnormality in the electronic component W, it is preferable to continuously measure the leakage current of the electronic component W at as short a time interval as possible. With a general measuring device, the leakage current of the electronic component W is usually measured at time intervals 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 time intervals shorter than 10 ms. For example, by continuously measuring the leakage current of the electronic component W at time intervals of 5 ms or less (more preferably 1 ms or less), it is possible to accurately detect abnormalities in the electronic component W that are difficult to detect by normal measurement using a general measuring device.

[0036] When measuring the electrical characteristics (leakage current characteristics) of the electronic component W in a state where a thermal 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. This heats the electrode 36 and / or the probe 31, and while the electrode 36 and the probe 31 are in contact with the electronic component W, it is possible to apply a voltage to the electronic component W, measure the leakage current, and heat the electronic component W (apply a thermal load).

[0037] 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 electric circuit 50.

[0038] [Inspection method] Figure 3 is a graph (antilogarithm graph) showing an example of the measurement results of the leakage current of an electronic component W (capacitor). The X-axis of Figure 3 shows the charging time (milliseconds (ms)), which is the elapsed time from the start of the measurement (origin (O)), and the Y-axis shows the measured value of the leakage current of the electronic component W (amperes (A)).

[0039] FIG. 3 shows the measurement results of leakage current of a normal electronic component W (capacitor) that does not contain any abnormalities (i.e., a “good product”) and the measurement results of leakage current of an electronic component that has an abnormality (i.e., a “defective product”) when a constant DC voltage is applied to the electronic component W (capacitor) to charge it.

[0040] As a result of extensive research into the behavior of the electrical characteristics (e.g., leakage current characteristics) of a capacitor (e.g., MLCC) during charging, the inventors of the present invention have newly discovered that a capacitor can exhibit temporary abnormal behavior during charging (see symbol "Ab" in Figure 3).

[0041] Such abnormal behavior can be identified by changes in the measured value of the leakage current of the capacitor, but the changes are not necessarily constant and the amount of change may be small.The present inventors have also newly discovered that there exist capacitors that exhibit abnormal behavior for a certain period of time (e.g., several tens of milliseconds to several seconds) and then return to normal behavior, and thereafter behave like good products.

[0042] Conventional inspection devices that detect capacitor anomalies based on the measured peak value of leakage current are suitable for detecting anomalies in which leakage current suddenly increases, but are not necessarily suitable for detecting anomalies in which leakage current decreases. Furthermore, conventional inspection devices cannot necessarily adequately handle capacitors that have an anomaly in which the leakage current is unstable for some reason, even if the insulation of the capacitor has not deteriorated.

[0043] Furthermore, while the capacity of MLCCs has been increasing in recent years, this increase in capacity has also led to a tendency for the ceramic layer of MLCCs to become thinner, making it difficult to apply high voltages to MLCCs for screening tests. Therefore, there is a demand for technology that can achieve highly reliable screening tests while keeping the voltage applied to MLCCs (capacitors) low.

[0044] For example, the device in Patent Document 1 detects a steep pulse-like abnormal current (leakage current) that occurs in a capacitor during charging. This type of device in Patent Document 1 is effective when the leakage current during charging exhibits stable behavior, but it is difficult to reliably detect abnormal current when the leakage current changes relatively drastically per unit time. In addition, the device in Patent Document 1 cannot detect an abnormality in which the leakage current of a capacitor decreases.

[0045] Furthermore, the device of Patent Document 2 judges the quality of a capacitor based on whether an evaluation function determined from the measured current value of the capacitor and the standard selection current value forms a convex curve upwards or downwards. However, as described in Patent Document 2 (see paragraph 0012), the device of Patent Document 2 treats temporary changes in the measured current value of the capacitor as noise and does not detect them as abnormalities. Furthermore, the device of Patent Document 1 cannot detect abnormalities in which the leakage current of the capacitor decreases.

[0046] As a result of repeated research based on the above findings, the present inventors have found a new technique that can effectively and accurately detect capacitor abnormalities that cannot be detected by conventional devices. That is, a new method has been found that accurately detects capacitor abnormalities based on a regression line derived from the logarithm of the measured value of the current (leakage current) of the electronic component W (capacitor) in a determination time range during charging of the electronic component W and the logarithm of the measurement timing of the current. According to this method, it is possible to accurately detect abnormal behavior that a capacitor having an abnormality temporarily exhibits during charging. In particular, even if the amount of change in the abnormal behavior is small or the abnormal behavior lasts for only a limited time (for example, tens of milliseconds to a few seconds), it is possible to accurately detect such abnormal behavior.

[0047] Although there are various variations of such anomaly detection methods, all of them are capable of detecting abnormal behavior of a capacitor based on a regression line. Typical examples of such anomaly detection methods are shown below, but anomaly detection methods that use a regression line in a form different from the typical examples below are also included in the present disclosure.

[0048] [First anomaly detection method] Fig. 4 is a graph (log-log graph) showing an example of the measurement results of the leakage current of the electronic component W, and is a graph for explaining the first anomaly detection method. The X-axis and Y-axis of Fig. 4 are based on a logarithmic scale, and the X-axis of Fig. 4 shows the charging time (milliseconds) which is the elapsed time from the start of the measurement (origin (O)) in logarithmic scale, and the Y-axis shows the measured value of the leakage current of the electronic component W (amperes) in logarithmic scale.

[0049] Fig. 4 shows the measurement results of leakage current of a normal electronic component W (capacitor) that does not contain any abnormalities (i.e., a "good product") and the measurement results of leakage current of an electronic component that has an abnormality (i.e., a "defective product") when a constant DC voltage is applied to the electronic component W (capacitor) to charge it. Fig. 4 also shows the "regression line Lr" obtained from the measurement results of the good product and the defective product based on the least squares method.

[0050] According to the inspection method based on the first abnormality detection technique, under the control of the control unit 55, a charging step, a current measuring step, and an abnormality detection step are performed.

[0051] In the charging step, the electronic component W (capacitor) is sandwiched between the probe 31 and the electrode 36 shown in Fig. 2 and a voltage is applied by the electric circuit 50 (voltage application unit 51) to charge the electronic component W. In the current measurement step, the current of the electronic component W (leakage current of the capacitor) during charging is continuously measured by the electric circuit 50 (current measurement unit 52). In this way, the current measurement step and the charging step are performed in parallel.

[0052] In the abnormality detection process, the control unit 55 (abnormality detection unit) detects an abnormality in the electronic component W (capacitor) based on a regression line Lr derived from the logarithm of the measured value of leakage current in a determination time range Tv during charging and the logarithm of the measurement timing of the leakage current. More specifically, the control unit 55 detects an abnormality in the electronic component W based on the degree of agreement between the regression line Lr and the logarithm of the measured value of leakage current and the logarithm of the measurement timing.

[0053] The "determination time range Tv" referred to here is a time range suitable for determining whether or not there is an abnormality in the electronic component W, and is specifically set to a time range in which the measurement results of a non-defective product highly match the regression line Lr. The optimal determination time range Tv is determined under the influence of the leakage current characteristics of the electronic component W and the voltage applied to the electronic component W, and may be set to a time range of 200 ms to 1500 ms after the start of charging (see the origin "O" in FIG. 4), for example.

[0054] The degree of agreement between the logarithm of the measured value of leakage current and the logarithm of the measurement timing with respect to the regression line Lr is typically calculated as a coefficient of determination based on the least squares method. The specific method of calculating the coefficient of determination is not limited, and the coefficient of determination can be calculated using a known formula.

[0055] For example, if the electronic component W is a non-defective product, the "degree of agreement between the logarithm of the measured leakage current value and the logarithm of the measurement timing with respect to the regression line Lr" will be relatively high, and the value of the coefficient of determination (contribution rate) based on the least squares method will also be relatively large. If the coefficient of determination for the case where the logarithm of the measured leakage current value and the logarithm of the measurement timing perfectly matches the regression line Lr is expressed as "100%, the coefficient of determination for a non-defective electronic component W can be, for example, 95.0% or more (as an example, 99.0% or more).

[0056] On the other hand, if the electronic component W is defective, the "degree of agreement of the logarithm of the measured leakage current value and the logarithm of the measurement timing with respect to the regression line Lr" will be relatively low, and the value of the coefficient of determination will also be relatively small, and may, for example, indicate a value smaller than 95.0% (as an example, a value smaller than 99.0%).

[0057] As described above, the electronic components W to be inspected can be classified as good or bad based on the coefficient of determination, but the threshold value of the coefficient of determination, which is the classification standard for good and bad products, is appropriately set according to the actual tolerance for abnormalities. In other words, the closer the threshold value is to "100%, the stricter the judgment of the presence or absence of abnormalities becomes, and even minor abnormalities are not tolerated, and as a result, the proportion of electronic components W that are judged to be defective tends to increase.

[0058] Therefore, the higher the requirement for reliability of the normality of the electrical characteristics (leakage current characteristics) of the electronic component W, the closer to "100%" the threshold value of the determination coefficient, which is the classification standard for good and bad products, is set. In order to satisfy the high level of reliability required in recent cutting-edge technologies, the threshold value of the determination coefficient may be required to be set to, for example, "99.0%" or a value higher.

[0059] In this way, the "degree of agreement between the logarithm of the measured leakage current value and the logarithm of the measurement timing with respect to the regression line Lr" represents the linearity of the logarithm of the measured leakage current value and the logarithm of the measurement timing, and can be expressed as a coefficient of determination based on the least squares method. However, the "degree of agreement between the logarithm of the measured leakage current value and the logarithm of the measurement timing with respect to the regression line Lr" may be obtained based on any other method that can directly or indirectly evaluate the linearity on a log-log graph of "charging time - measured current".

[0060] For example, the control unit 55 (abnormality detection unit) may determine the "degree of mismatch" of the logarithm of the measured leakage current value and the logarithm of the measurement timing with respect to the regression line Lr by any method, and detect an abnormality in the electronic component W based on the degree of mismatch. The control unit 55 (abnormality detection unit) may also extract data on the measured leakage current value of the electronic component W to be inspected only for a partial time range (judgment time range Tv) during the charging time. In this case, the control unit 55 may detect an abnormality in the electronic component W based on the regression line Lr derived from the logarithm of the extracted measured leakage current value and the logarithm of the measurement timing of the leakage current.

[0061] The control unit 55 controls the electronic component ejection unit 14 based on the results of the inspection including the series of processes described above, and ejects electronic components W determined to be abnormal and electronic components W not determined to be abnormal into separate collection boxes of the collection device 16 via the ejection path 15.

[0062] [Second anomaly detection method] In the following description of the second anomaly detection method, detailed description of the same processes as those in the above-described first anomaly detection method (see FIG. 4) will be omitted.

[0063] Fig. 5 is a graph (log-log graph) showing an example of the measurement results of the leakage current of the electronic component W, and is a graph for explaining the second anomaly detection method. The X-axis and Y-axis of Fig. 5 are represented by logarithmic scales, and the X-axis of Fig. 5 shows the charging time (milliseconds) which is the elapsed time from the start of the measurement (origin (O)) in logarithmic scale, and the Y-axis shows the measured value of the leakage current of the electronic component W (amperes) in logarithmic scale.

[0064] Fig. 5 shows the measurement results of a pass / fail electronic component, as well as the regression line Lr obtained based on the measurement results of the pass / fail electronic components. Fig. 5 also shows the upper limit B1 and lower limit B2 of the allowable current range.

[0065] In the inspection method based on the second abnormality detection technique, a charging step, a current measurement step, and an abnormality detection step are also performed, and in particular the charging step and the current measurement step are performed in the same manner as in the inspection method based on the above-described first abnormality detection technique.

[0066] However, in the abnormality detection process based on the second abnormality detection method, the control unit 55 (abnormality detection unit) determines whether or not the logarithm of the measured value of the leakage current of the electronic component W in the judgment time range Tv is included in the allowable current range defined based on the regression line Lr. That is, an abnormality in the electronic component W (capacitor) is detected based on the relationship of the logarithm of the measured value of the leakage current to at least one of the upper limit B1 and the lower limit B2 of the allowable current range defined based on the regression line Lr over the judgment time range Tv.

[0067] In the double logarithmic graph of FIG. 5, the area between the line (upper limit) indicated by the symbol "B1" and the line (lower limit) indicated by the symbol "B2" corresponds to the current tolerance range, and the regression line Lr exists in this area (current tolerance range) in the judgment time range Tv.

[0068] As described above, the electronic component W to be inspected can be classified as a good or bad product based on the current tolerance (upper limit B1 and lower limit B2), but the upper limit B1 and lower limit B2 that determine the current tolerance correspond to thresholds that are the classification criteria for good and bad products, and are appropriately set according to the actual tolerance for abnormalities. In other words, the closer the upper limit B1 and lower limit B2 of the current tolerance are to the regression line Lr, the stricter the judgment of the presence or absence of an abnormality becomes, and even minor abnormalities are not tolerated, and the proportion of electronic components W that are determined to be defective tends to increase. Therefore, the higher the requirement for reliability of the normality 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 tolerance that are the classification criteria for good and bad products are set to values ​​that are closer to the regression line Lr.

[0069] The specific method of determining the upper limit B1 and the lower limit B2 of the current tolerance range is not limited. For example, the difference between the regression line Lr and the upper limit B1 or the lower limit B2 of the current tolerance range may be the same or different between the upper limit B1 and the lower limit B2 of the current tolerance range. Furthermore, the difference between the regression line Lr and the upper limit B1 or the lower limit B2 of the current tolerance range may be the same or different throughout the entire judgment time range Tv. Therefore, in the log-log graph of "charging time-measured current" (see FIG. 5), the line indicating the upper limit B1 and the line indicating the lower limit B2 of the current tolerance range may be parallel or non-parallel to the regression line Lr.

[0070] Also, the upper limit B1 and the lower limit B2 of the current allowable range may be determined from the value of the regression line Lr (the value of the Y-axis related to the measured current) at a plurality of discrete time timings selected from the judgment time range Tv. For example, the upper limit B1 and the lower limit B2 of the current allowable range may be determined based on the regression line Lr for two points, the "start time timing (start point)" and the "end time timing (end point)" of the judgment time range Tv. In this case, in a double logarithmic graph of "charging time - measured current" (see FIG. 5), the upper limit B1 of the current allowable range throughout the entire judgment time range Tv may be determined by a straight line passing through these two points (start point and end point) related to the upper limit B1 of the current allowable range. Similarly, in a double logarithmic graph of "charging time - measured current", the lower limit B2 of the current allowable range throughout the entire judgment time range Tv may be determined by a straight line passing through these two points (start point and end point) related to the lower limit B2 of the current allowable range.

[0071] Furthermore, the control unit 55 (abnormality detection unit) may set only one of the upper limit B1 and the lower limit B2 of the allowable current 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 allowable current range may be set to the same value as the regression line Lr.

[0072] In the above-mentioned abnormality detection process, if the entire measured current of the electronic component W in the determination time range Tv is within the allowable current range (e.g., including the boundaries (upper limit B1 and lower limit B2)), the control unit 55 can determine that the electronic component W has no abnormality. On the other hand, if at least a part of the measured current of the electronic component W in the determination time range Tv is outside the allowable current range (e.g., not including the boundaries (upper limit B1 and lower limit B2)), the control unit 55 can determine that the electronic component W has an abnormality.

[0073] Then, the control unit 55 controls the electronic component ejection unit 14 based on the results of the inspection including the series of steps described above, and ejects the electronic components W determined to be abnormal and the electronic components W not determined to be abnormal into separate collection boxes of the collection device 16 via the ejection path 15.

[0074] [Application of anomaly detection methods] The above-mentioned first and second anomaly detection techniques (see Figures 4 and 5) or other detection techniques based on the regression line Lr can be applied to an inspection method for an electronic component W as follows, making it possible to accurately detect anomalies in the electronic component W.

[0075] [Application example 1] FIG. 6 is a log-log graph of "charging time vs. measured current" showing an example of typical electrical characteristics of a capacitor.

[0076] The correlation between the logarithm of the charging time and the logarithm of the leakage current of a capacitor when a constant DC voltage is applied to the capacitor to charge it is not necessarily constant throughout the charging time, but there are multiple stages (see "P1" to "P3" in FIG. 6) that show an inherent linearity (proportional relationship). In the example shown in FIG. 6, there is a first stage P1 where the leakage current of the capacitor is almost constant, a second stage P2 where the leakage current decreases rapidly, and a third stage P3 where the leakage current decreases more rapidly than the first stage P1 and more gently than the second stage P2. In the double logarithmic graph shown in FIG. 6, the "charging time - measured current" shows a proportional correlation in all of the first stage P1 to the third stage P3, but the proportion of the proportional correlation (i.e., the slope of the linearity) of the "charging time - measured current" differs between the first stage P1 to the third stage P3.

[0077] The control unit 55 (abnormality detection unit) can detect an abnormality in the electronic component W (capacitor) for each stage by setting a determination time range Tv and a regression line Lr for each stage.

[0078] That is, the control unit 55 can detect an abnormality in the electronic component W in a first judgment time range based on a first regression line derived from the logarithm of the measurement value of the leakage current of the electronic component W in a first judgment time range during charging and the logarithm of the measurement timing of the leakage current. On the other hand, the control unit 55 can detect an abnormality in the electronic component W in a second judgment time range based on a second regression line derived from the logarithm of the measurement value of the leakage current of the electronic component W in a second judgment time range during charging and the logarithm of the measurement timing of the leakage current.

[0079] By setting the "first judgment time range" and the "second judgment time range" here to different stages (see the first stage P1, the second stage P2, and the third stage P3 in FIG. 6), it is possible to detect an abnormality in the electronic component W in each of the multiple stages. Note that, if there are three or more stages in the correlation between the charging time of the capacitor and the leakage current, three or more judgment time ranges may be set to be assigned to the respective stages.

[0080] For example, in the example shown in FIG. 6, a "first judgment time range Tv1" may be set in the first stage P1, a "second judgment time range Tv2" may be set in the second stage P2, and a "third judgment time range Tv3" may be set in the third stage P3. In this case, a first regression line Lr1 is determined based on the measurement result of the leakage current in the first judgment time range Tv1, a second regression line Lr2 is determined based on the measurement result of the leakage current in the second judgment time range Tv2, and a third regression line Lr3 is determined based on the measurement result of the leakage current in the third judgment time range Tv3. Then, using the above-mentioned anomaly detection method (see FIG. 4 and FIG. 5), an anomaly of the electronic component W in the first judgment time range Tv1 can be detected based on the first regression line Lr1, an anomaly of the electronic component W in the second judgment time range Tv2 can be detected based on the second regression line Lr2, and an anomaly of the electronic component W in the third judgment time range Tv3 can be detected based on the third regression line Lr3.

[0081] The "first judgment time range" and the "second judgment time range" may be set in a common stage. For example, the "first judgment time range" and the "second judgment time range" (and the third and subsequent judgment time ranges) may be set in one stage (see the third stage P3 in FIG. 6) that occupies a relatively long time range.

[0082] [Application example 2] The inspection device 13 may perform multiple electrical inspections on each electronic component W. Such multiple electrical inspections may include two electrical inspections in which the polarities (direct current) of the current when applying an inspection voltage to each electronic component W are different from each other (the orientation of the positive and negative poles).

[0083] That is, the electric circuit 50 (voltage application unit 51; see FIG. 2) may apply a voltage with a first polarity to the electronic component W (capacitor) to perform first polarity charging, and after the first polarity charging, may apply a voltage with a second polarity opposite to the first polarity to the electronic component W to perform second polarity charging. In this case, the electric circuit 50 (current measurement unit 52) ​​measures a first polarity current that is a leakage current of the electronic component W during first polarity charging, and measures a second polarity current that is a leakage current of the electronic component W during second polarity charging. Then, the control unit 55 (abnormality detection unit) can detect an abnormality in the electronic component W (capacitor) based on a first polarity regression line derived from the logarithm of the measured value of the first polarity current in a first judgment time range during the first polarity charging and the logarithm of the measurement timing of the first polarity current. Similarly, the control unit 55 can detect an abnormality in the electronic component W (capacitor) based on a second polarity regression line derived from the logarithm of the measurement value of the second polarity current in the second judgment time range during second polarity charging and the logarithm of the measurement timing of the second polarity current. Note that when a negative voltage is applied to the electronic component W (e.g., in the case of second polarity charging), the measurement value of the leakage current (e.g., second polarity current) of the electronic component W also becomes negative, so the regression line may be derived from the logarithm of the absolute value of the measurement value of the leakage current.

[0084] The capacitor of the electronic component W may exhibit specific electrical characteristics depending on the polarity of the applied current, and may exhibit abnormal leakage current behavior only when a voltage of a first polarity or a voltage of a second polarity is applied. Even if the electronic component W to be inspected has such a polarity, by performing an electrical inspection for each of the first polarity and the second polarity as in this application example, it is possible to reliably detect an abnormality in the electronic component W.

[0085] As described above, according to the inspection device 13 and the inspection method described above, an abnormality in the electronic component W (capacitor) can be detected based on the regression line Lr derived from the logarithm of the measured value of the leakage current of the electronic component W in the judgment time range Tv during charging and the logarithm of the measurement timing of the leakage current.

[0086] In particular, even if an electronic component W having an abnormality exhibits abnormal behavior only temporarily during charging, the above-described inspection device 13 and inspection method can properly detect the abnormality of such an electronic component W. Moreover, even if 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-described inspection device 13 and inspection method can properly detect the abnormality of such an electronic component W.

[0087] Moreover, the above-described inspection device 13 and inspection method can detect not only an abnormality in which the leakage current of the electronic component W increases, but also an abnormality in which the leakage current decreases. Even if the inspection voltage applied to the electronic component W to be inspected is low, the abnormality of the electronic component W can be detected with high reliability.

[0088] Furthermore, electronic components W whose leakage current per unit time fluctuates relatively drastically even in a normal state may be inspected, and the above-mentioned second anomaly detection method (see FIG. 5) makes it possible to accurately detect anomalies in such electronic components W. That is, by determining the upper limit B1 and / or lower limit B2 of the current tolerance range in consideration of the magnitude of fluctuation in leakage current in the normal state of the electronic component W, it is possible to detect true "anomalies" in the electronic component W while preventing fluctuations in leakage current in the normal state from being detected as "anomalies." Furthermore, such a second anomaly detection method makes it possible to detect "anomalies in which the insulation of the electronic component W (capacitor) has not deteriorated but the leakage current is unstable for some reason."

[0089] It should be noted that the embodiments and modifications disclosed in this specification are merely illustrative and should not be construed as limiting in all respects. The above-mentioned embodiments and modifications can be omitted, substituted, and modified in various forms without departing from the scope and spirit of the appended claims. For example, the above-mentioned embodiments and modifications may be combined in whole or in part, and embodiments other than those described above may be combined with the above-mentioned embodiments or modifications. In addition, the effects of the present disclosure described in this specification are merely illustrative, and other effects may be obtained.

[0090] The technical category embodying the above technical idea is not limited. For example, the above technical idea may be embodied by a computer program for causing a computer to execute one or more procedures (steps) included in a method for manufacturing or using the above device. The above technical idea may also be embodied by a non-transitory recording medium readable by a computer on which such a computer program is recorded. [Explanation of symbols]

[0091] 10 inspection system, 10A structure, 10a inclined surface, 11 index table, 11a rotating shaft, 12 pocket, 13 inspection device, 14 electronic component discharge section, 15 discharge path, 16 recovery device, 18 supply feeder, 19 electronic component supply section, 30 probe unit, 31 probe, 32 compression spring, 33 probe base, 35 electrode unit, 36 electrode, 37 electrode base, 38 electrode heater, 40 probe holder, 41a holder body, 41b holder body, 41c holder body, 41d holder body, 42a sheet material, 42b sheet material, 43 probe heater, 50 electrical circuit, 51 voltage application section, 52 current measurement section, 55 control section, 60 index table cover, 61 first front cover, 62 second front cover, 63 third front cover, B1 upper limit, B2 Lower limit, Lr regression line, Lr1 1st regression line, Lr2 2nd regression line, Lr3 3rd regression line, P1 1st stage, P2 2nd stage, P3 3rd stage, Tv judgment time range, Tv1 1st judgment time range, Tv2 2nd judgment time range, Tv3 3rd judgment time range, W electronic component

Claims

1. a voltage application unit that applies a voltage to the capacitor to charge it; a current measuring unit that continuously measures a current through the capacitor during charging; an abnormality detection unit that detects an abnormality in the capacitor based on a regression line derived from a logarithm of the measured current value in a determination time range during charging and a logarithm of a measurement timing of the current; An inspection device comprising:

2. The inspection device according to claim 1 , wherein the abnormality detection unit detects an abnormality in the capacitor based on a degree of coincidence of the logarithm of the measured current value and the logarithm of the measurement timing with respect to the regression line.

3. 3. The inspection device according to claim 1, wherein the abnormality detection unit detects an abnormality in the capacitor based on a logarithmic relationship of the measured current value with respect to at least one of an upper limit and a lower limit of an allowable current range defined based on the regression line over the judgment time range.

4. The abnormality detection unit detecting an abnormality in the capacitor based on a first regression line derived from a logarithm of the measured value of the current in a first determination time range during the charging and a logarithm of a measurement timing of the current; 3. The inspection device according to claim 1, further comprising: a second regression line derived from the logarithm of the measured current value in a second judgment time range during charging and the logarithm of the measurement timing of the current.

5. The voltage application unit is applying a voltage to the capacitor with a first polarity to perform first polarity charging; After the first polarity charging, a voltage is applied to the capacitor with a second polarity that is opposite to the first polarity to perform second polarity charging; The current measuring unit is measuring a first polarity current, which is a current through the capacitor during the first polarity charging; measuring a second polarity current, which is a current through the capacitor during the second polarity charging; The abnormality detection unit detecting an abnormality in the capacitor based on a first polarity regression line derived from a logarithm of a measurement value of the first polarity current in a first determination time range during the first polarity charging and a logarithm of a measurement timing of the first polarity current; 3. The inspection device according to claim 1, wherein an abnormality in the capacitor is detected based on a second polarity regression line derived from the logarithm of the measurement value of the second polarity current in a second judgment time range during the second polarity charging and the logarithm of the measurement timing of the second polarity current.

6. applying a voltage to the capacitor to charge it; continuously measuring the current through the capacitor during the charging; detecting an abnormality in the capacitor based on a regression line derived from a logarithm of the measured current value in a determination time range during charging and a logarithm of a measurement timing of the current; The inspection method includes:

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