Calibration method, measurement device, and inductor

Abstract

The invention provides a correction method, a measurement device, and an inductor inspection method. The calibration method includes: an open-circuit reference measurement step of measuring electrical characteristics in an open-circuit state in which the contact does not come into contact with another object and acquiring an open-circuit reference measurement value; a reference measurement step for measuring the electrical characteristics of a reference substance by bringing the contact into contact with the reference substance having known electrical characteristics; and a calculation step for calculating, on the basis of the open-circuit reference measurement value, a reference value that is a known electrical characteristic of the reference object, and a measurement reference value that is a result of measuring the electrical characteristic of the reference object, a transmission parameter indicating a characteristic of a transmission path from the measurement unit to the object. The reference measurement step is performed a plurality of times so as to repeatedly contact and separate the contact and the reference substance, and in the calculation step, representative values of the measurement reference values are acquired from the plurality of measured measurement reference values, and the transmission parameter is calculated on the basis of the representative values of the measurement reference values.

Description

Technical Field

[0001] The present invention relates to a calibration method, a measuring device, and an inductor inspection method. Background Art

[0002] Patent Document 1 discloses a calibration method for a vector network analyzer. This calibration method calculates S parameters for each measurement cable, from the vector network analyzer (VNA) to the end of the measurement cable. Then, based on the S parameters from the VNA to the end of the measurement cable and characteristic data related to short circuits, open circuits, and loads associated with the connector, multiple S parameters are calculated for each connector. From these calculated S parameters, one S parameter corresponding to the measurement frequency is selected.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2006-317156

[0006] In measurement devices that measure electrical characteristics, measurement errors may occur due to the transmission characteristics of the electrical signal transmission path from a measurement unit that inputs and outputs the electrical signal to the object being measured. Therefore, as disclosed in Patent Document 1, measurement devices are calibrated before measuring the object to eliminate the influence of transmission path losses on measurement errors.

[0007] As a method for calibrating a measuring device, there is known a method in which the measuring device measures the electrical characteristics of a reference object (reference device) with known electrical characteristics to obtain transmission parameters representing the characteristics of a transmission path, and performs calibration using the transmission parameters.

[0008] In this calibration method, the transmission parameters are obtained based on the electrical characteristics measured by bringing the contactor of the measuring device into contact with a reference object. Therefore, if the contact state (contact resistance) between the contactor and the reference object is different, the value of the transmission parameter will vary, resulting in measurement error.

[0009] Typically, the impact of calibration on measurement errors is minimal, and therefore, has not been considered in the past. However, with the recent demand for higher functionality and smaller electronic components, there is a growing demand for higher precision in the electrical characteristics of these components. Consequently, there is a need to reduce measurement errors during calibration of measurement devices. Summary of the Invention

[0010] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a calibration method of a measuring device, a measuring device, and an inductor inspection method that reduce measurement errors.

[0011] According to a certain embodiment of the present invention, a calibration method for a measuring device includes: an open-circuit reference measurement process, in which electrical characteristics are measured in an open-circuit state in which the contact is not in contact with other objects to obtain an open-circuit reference measurement value; a reference measurement process, in which the contact is brought into contact with a reference object with known electrical characteristics to measure the electrical characteristics of the reference object to obtain a reference measurement value; and an operation process, in which transmission parameters representing the characteristics of a transmission path from a measuring part to an object are operated based on the open-circuit reference measurement value, a reference value of a known electrical characteristic possessed by the reference object, and a reference measurement value as a result of measuring the electrical characteristics of the reference object, the reference measurement process being performed multiple times in such a manner that the contact is repeatedly brought into contact with the reference object, and in the operation process, a representative value of the measurement reference value is obtained based on the multiple measured measurement reference values, and the transmission parameters are operated based on the representative value of the measurement reference value.

[0012] In addition, according to a certain embodiment of the present invention, the measuring device includes: a contact, which contacts an object; a measuring unit, which brings the contact into contact with the object and measures the electrical characteristics of the object through the contact; and a processing unit, which processes the measurement results obtained by the measuring unit, and the processing unit is configured to perform the following steps: measuring the electrical characteristics in an open circuit state where the contact is not in contact with other objects to obtain an open circuit reference measurement value; bringing the contact into contact with a reference object with known electrical characteristics to measure the electrical characteristics of the reference object to obtain a measurement reference value; and calculating a transmission parameter representing the characteristics of a transmission path between the measuring unit and the object based on the open circuit reference measurement value, a reference value of a known electrical characteristic of the reference object, and a measurement reference value obtained by measuring the electrical characteristics of the reference object, the step of obtaining the measurement reference value is performed multiple times in a manner that repeatedly brings the contact into contact with the reference object, and in the step of calculating the transmission parameter, a representative value of the measurement reference value is obtained based on multiple measurement reference values, and the transmission parameter is calculated based on the representative value of the measurement reference value.

[0013] Furthermore, according to one aspect of the present invention, an inspection method for inspecting an inductor includes: a calibration step of acquiring transmission parameters representing characteristics of a transmission path between a contact of a measuring device and a measuring section, and calibrating the measuring device based on the transmission parameters; and an inspection step of bringing the contact into contact with the inductor to measure electrical characteristics and inspect whether the inductor is good, the calibration step including: an open-circuit reference measurement step of measuring the electrical characteristics in an open-circuit state where the contact is not in contact with any other object to obtain an open-circuit reference measurement value; a reference measurement step of bringing the contact into contact with a reference object with known electrical characteristics to measure the electrical characteristics of the reference object to obtain a reference measurement value; calculating the transmission parameter representing characteristics of the transmission path from the measuring section to the contact based on the open-circuit reference measurement value, a reference value representing the known electrical characteristics of the reference object, and a measurement reference value representing the result of measuring the electrical characteristics of the reference object; and a device calibration step of calibrating the inspection device based on the transmission parameters, the reference measurement step being performed multiple times with the contact repeatedly brought into contact, and in a calculation step, obtaining a representative value of the measurement reference values ​​based on the measurement reference values ​​measured multiple times, and calculating the transmission parameter based on the representative value of the measurement reference values.

[0014] Effects of the Invention

[0015] In these schemes, characteristic parameters are calculated based on representative values ​​of reference measurement values ​​obtained through multiple measurements of a reference object. Therefore, even if the contact state between the contactor and the reference object varies, characteristic parameters close to the true value can be obtained. This reduces measurement errors caused by calibration. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a diagram showing the configuration of a measuring device and an inspection device according to an embodiment of the present invention.

[0017] Figure 2 This is a flowchart showing the inspection process in the inspection method according to this embodiment.

[0018] Figure 3 This is a circuit diagram for explaining the principle of the correction method of this embodiment.

[0019] Figure 4 This is a flowchart showing a calibration step (calibration method) in the inspection method according to the present embodiment.

[0020] Figure 5 This is a table showing reference measurement values ​​measured in the calibration method of this embodiment.

[0021] Figure 6 This is a table showing the corrected resistance values ​​in the calibration method of this embodiment.

[0022] Figure 7This is a flowchart showing a maintenance warning process in the calibration method according to the present embodiment.

[0023] Description of reference numerals:

[0024] 100: Inspection device; 10: Measuring device; 20: Measuring unit; 30: Processing unit; 40: Contactor; 41a: Contactor; 41b: Contactor; 41c: Contactor; 41d: Contactor; 42a: Contactor; 42b: Contactor. DETAILED DESCRIPTION

[0025] Hereinafter, a calibration method, an inspection method, a measuring device 10 , and an inspection device 100 according to embodiments of the present invention will be described with reference to the drawings.

[0026] First, refer to Figure 1 , the overall structure of the measuring device 10 and the inspection device 100 according to the embodiment will be described. Figure 1 It is a diagram showing the configuration of the inspection apparatus 100 according to the embodiment.

[0027] The following description uses the example of an inductor as the target object for measurement and inspection (DUT: Device Under Test, hereinafter referred to as "DUT"). Inspection apparatus 100 measures the Q value, an electrical characteristic of the DUT, and inspects the DUT based on the measured Q value to determine if it is defective. It should be noted that the DUT can also be other components such as capacitors and filters.

[0028] like Figure 1 As shown, the inspection device 100 includes: a measuring device 10, which measures the Q value of the DUT to check whether the DUT is good; a display unit 70, which displays a signal corresponding to the signal received from the measuring device 10; an operation unit 80, which is operated by an operator and outputs an operation signal corresponding to the operation to the measuring device 10; and a conveying device 90, which conveys the DUT.

[0029] The transport device 90 is configured to transport a DUT supplied from an external source to a measurement location to be measured by the measurement device 10, and to output the DUT having its Q value measured. The operation of the transport device 90 is controlled by the processing unit 30 of the measurement device 10, which will be described later. The transport device 90 can employ a known configuration, and therefore detailed description and illustration are omitted.

[0030] The measuring device 10 measures the Q value of the DUT and determines whether the DUT is good or not based on this Q value. In this embodiment, if the measured Q value is above a preset inspection threshold, the DUT is determined to be good, and if the measured Q value is below the inspection threshold, the DUT is determined to be defective. The result of the good or bad determination obtained by the measuring device 10 is transmitted to the display unit 70 and displayed on the display unit 70 in a format that can be viewed by the operator.

[0031] The measuring device 10 includes a contactor that contacts the DUT, a measuring unit 20 that measures the Q value of the DUT based on an electrical signal applied to the DUT, and a processing unit 30 that processes the measurement result obtained by the measuring unit 20 .

[0032] The measuring unit 20 connects the two contacts 41a and 41b via a transmission unit 45 that transmits an electrical signal. The measuring unit 20 performs measurement using a two-terminal measurement method. When the contacts 41a and 41b are not distinguished, they are collectively referred to as "contacts 40" in the following description.

[0033] The measuring unit 20 is an LCR meter that measures inductance, capacitance, resistance, impedance, etc. It should be noted that the measuring unit 20 is not limited to an LCR meter, and may be, for example, a vector network analyzer (VNA).

[0034] The contactor 40 is a probe that is moved forward and backward relative to the DUT by a driving unit (not shown) to contact the terminal of the DUT, which is an inductor element. The driving unit is controlled by the processing unit 30. The transmission unit 45 is a cable that electrically connects the contactor 40 and the measurement unit 20 to transmit electrical signals between the contactor 40 and the measurement unit 20.

[0035] The measurement unit 20 applies a current to the DUT via the contactors 41 a and 41 b and detects a voltage generated in the DUT.

[0036] The processing unit 30 is a computer equipped with a CPU (Central Processing Unit) and other processing devices, a storage device, a display device, an input device, and a network connection device. The processing unit 30 is electrically connected to the measuring unit 20, controls the operation of the measuring unit 20, and obtains measurement results obtained by the measuring unit 20. The processing unit 30 performs the various processes described in this manual by having the CPU execute programs pre-stored in the storage device.

[0037] It should be noted that the processing unit 30 of the measurement device 10 is composed of a single computer, but the present invention is not limited thereto and may be composed of a plurality of microcomputers and configured so that each control is processed in a distributed manner by the plurality of computers.

[0038] The measuring unit 20 measures the DC resistance of the DUT using a two-terminal measurement method using a DC current as an electrical signal, and measures the effective resistance and inductance of the DUT using a two-terminal measurement method using a high-frequency signal as an electrical signal. The processing unit 30 calculates the Q value using the DC resistance, effective resistance, and inductance values ​​measured by the measuring unit 20. The processing unit 30 then determines whether the DUT is defective based on the calculated Q value. In this manner, the inspection apparatus 100 performs DUT inspection.

[0039] Below, refer to Figures 2 to 7 , the calibration method and inspection method of the measuring device 10 of this embodiment are described in detail. Figure 2 This is a flowchart showing the inspection process in the inspection method according to this embodiment.

[0040] Figure 3 This is a circuit diagram for explaining the principle of the correction method of this embodiment. Figure 4 This is a flowchart showing a calibration step (calibration method) in the inspection method according to the present embodiment. Figure 5 This is a table showing reference measurement values ​​measured in the calibration method of this embodiment. Figure 6 This is a table showing the corrected resistance values ​​in the calibration method of this embodiment. Figure 7 1 is a flowchart showing a maintenance warning process in the calibration method according to this embodiment.

[0041] The inspection method of this embodiment is performed as part of a manufacturing method for an electronic component, such as an inductor element or capacitor, which serves as a device under test (DUT). For example, the manufacturing method for an inductor element includes the following steps: forming electrodes on a core by plating; winding wire around the core; applying resin to the core including the winding to form the inductor element; and inspecting the inductor element. The inspection method of this embodiment is performed during this inspection step.

[0042] The inspection method of this embodiment includes the following steps: calibrating the measuring unit 20 of the measuring device 10 (calibration process); and inspecting the DUT using the calibrated measuring device 10 (inspection process). Figure 2 As shown, the inspection process includes the following steps: supplying the DUT to a measurement position to be measured by the measuring unit 20 (a first conveying process); measuring the electrical characteristics of the DUT by the measuring unit 20 (a measuring process); calculating the Q value of the DUT (a calculating process); judging whether the DUT is good based on the measured Q value (a judging process); and conveying the inspected DUT from the measurement position to a downstream process outside the inspection device 100 (a second conveying process).

[0043] In the calibration process, in order to obtain the Q value of the DUT based on the measured value obtained by the measuring unit 20 of the measuring device 10, a reference (reference object) with a known resistance value as an electrical characteristic is used for calibration. In this embodiment, the equivalent series resistance (ESR) is used as the resistance value of the reference. Therefore, in the following description of the calibration process, the resistance value measured by the measuring unit 20 refers to the equivalent series resistance. The calibration method performed by the measuring device 10 as the calibration process will be described in detail later.

[0044] After the calibration process is completed, for example, when the operation unit 80 is operated by the operator and an operation signal from the operation unit 80 is received (see Figure 1 ), the inspection process is executed by the processing unit 30. The inspection process is executed by the processing unit 30 controlling each component of the inspection device 100.

[0045] like Figure 2 As shown in FIG, in the inspection process, first, a first transport process is performed. In the first transport process, the DUT to be inspected is transported to a measurement position by the transport device 90 .

[0046] During the measurement process, the contactor 40 of the measuring unit 20 is brought into contact with the DUT at the measurement position by the driving unit of the measuring device 10, and the DC resistance, effective resistance, and inductance are measured by the measuring unit 20. It should be noted that the driving unit may be provided on the conveying device 90 instead of on the measuring device 10 side.

[0047] When the measurement process is complete, the calculation process is executed. In the calculation process, the Q value is calculated based on the resistance value, effective resistance value, and inductance value measured in the measurement process by the processing unit 30. The process of calculating the Q value is well known, so its detailed description is omitted.

[0048] After the calculation process is complete, the determination process is executed. In the determination process, the processing unit 30 compares the Q value calculated in the calculation process with a pre-set inspection threshold to determine whether the DUT is good. In the determination process, if the calculated Q value is greater than or equal to the inspection threshold, the device is determined to be good; if the calculated Q value is less than the inspection threshold, the device is determined to be defective. The inspection threshold is set based on, for example, the standard value of the Q value required by the DUT.

[0049] When the determination step is completed, the second transport step is executed, and the DUT at the measured position is transported to a downstream step outside the inspection apparatus 100 by the transport device 90 .

[0050] When the second transport process is complete, the first transport process is repeated to transport a new DUT to be inspected to the measurement position. The inspection process is then repeated for the new DUT. This process is repeated to continuously inspect multiple DUTs.

[0051] Next, a calibration method of the measurement device 10 according to the present embodiment will be described as a calibration step in the inspection method.

[0052] First, the principle of the calibration method of this embodiment will be described.

[0053] If the DC resistance of the DUT is measured by the measuring device 10, the transmission path between the measuring unit 20 of the LCR meter and the DUT, which is composed of the contact 40 and the transmission unit 45, can be considered as follows: Figure 3 The two-terminal pair circuit shown. The input / output of the two-terminal pair circuit can be expressed by the following formula (1). It should be noted that V1 in formula (1) is the input voltage, V2 is the output voltage, I1 is the input current, and I2 is the output current. A to D in the following formula are transmission parameters called F parameters. The transmission parameters represent the transmission characteristics of the transmission path from the measuring device 10 to the DUT, including the contact 40 and the transmission part 45.

[0054]

[0055] In this two-terminal pair circuit, the measured value Rdm of the DC resistance obtained by the measuring unit 20 is expressed as Rdm=V1 / I1. The true value Rd of the DC resistance of the DUT is expressed as Rd=V2 / I2.

[0056] Therefore, a correction formula for correcting (correcting) the measured value Rdm obtained by the measuring device 10 to the true value Rd of the DC resistance of the DUT can be expressed by the following equation (2).

[0057]

[0058] Furthermore, the correction formula for correcting the measured value Rdm can be obtained by calculating the three constants B', C', and A' in the formula. The three constants can be obtained by measuring the resistance values ​​of three reference devices with different resistance values ​​and substituting the measured values ​​and the reference values ​​into the above formula (2) to obtain the three simultaneous equations.

[0059] In this embodiment, the resistance value is measured under three references: an open-circuit reference with an infinite resistance value (i.e., open), a short-circuit reference with a zero resistance value (i.e., short-circuited), and a load reference with a predetermined resistance value different from the open-circuit reference and the short-circuit reference. The above-mentioned correction formula (Formula (2)) is obtained to calibrate the measuring device 10. In this way, by obtaining the correction formula, in other words, by obtaining the transmission parameters, the measured value of the measuring device 10 can be calibrated to the resistance value of the DUT.

[0060] Below, refer to Figure 4 The calibration method performed by the measuring device 10 will be described in detail.

[0061] For example, when the operator operates the operation unit 80 to execute the calibration method, a command signal is sent from the operation unit 80 to the processing unit 30 of the measurement device 10. When the command signal for executing the calibration method is received, the processing unit 30 executes the calibration method. Figure 4 The processing unit 30 of the measurement device 10 is programmed to execute the following calibration method.

[0062] The correction method of this embodiment includes: an open circuit reference measurement process, in which the resistance value is measured in an open circuit state in which the contact 40 is not in contact with other objects to obtain an open circuit reference measurement value Rmo; a reference measurement process, in which the contact 40 is brought into contact with a reference device with known electrical characteristics to measure the resistance value of the reference device to obtain a reference measurement value; and a calculation process, in which the transmission parameters representing the characteristics of the transmission path from the measuring unit 20 to the DUT are calculated based on the open circuit reference measurement value Rmo, the reference value as the known resistance value of the reference device, and the measurement reference value as the result of measuring the electrical characteristics of the reference device.

[0063] like Figure 4 As shown, in the open reference measurement process shown in step S10, the resistance value is measured in the open state, without contacting the contact 40 or any other object such as a reference. The measured value under the open reference (hereinafter referred to as "open reference measurement value Rmo") is temporarily stored in the measuring unit 20. It should be noted that since there is little deviation due to the absence of contact between the contact 40 and the reference, the open reference measurement value Rmo is measured only once. Furthermore, the reference value under the open reference is referred to as "open reference value Rdo."

[0064] After the open-circuit reference measurement process is completed, the reference measurement process shown in steps S11 and S12 is executed. In step S11, the resistance value of the reference device corresponding to the short-circuit reference is measured, and in step S12, the resistance value of the reference device corresponding to the loaded reference is measured. In this embodiment, the contact 40 and the reference device are repeatedly brought into contact and separated for both the short-circuit reference and the loaded reference, and the resistance value is measured during each repetition, thereby obtaining multiple measurement values.

[0065] To explain specifically, first, the reference device corresponding to the short-circuit reference is set at the measurement position by the conveying device 90. Then, the contact 40 is moved toward the reference device and brought into contact with the reference device to measure the resistance value. When the resistance value is measured once in this way, the contact 40 is retracted from the reference device to separate the contact 40 from the reference device (become non-contact). Then, the contact 40 is moved toward the reference device again and brought into contact with the reference device to remeasure the resistance value. The above steps are repeated to measure the resistance value of the reference device of the short-circuit reference multiple times according to a predetermined number of times. This will be explained in detail later, but in this embodiment, any multiple (three in this embodiment) measurement values ​​that meet the selected completion conditions described later are selected from the multiple measurement values. The number of times the resistance value is measured can be any number (three in this embodiment) of measurement values ​​that can select at least the selected completion conditions described later. However, if a measurement value does not satisfy the selected completion condition, the reference device must be replaced and additional measurements performed. Therefore, in order to reduce the need for reference device replacement associated with additional measurements, this step predetermines the number of resistance measurements to be greater than the number of times a measurement value satisfying the selected completion condition can be selected. In this embodiment, five resistance measurements are performed (step S11).

[0066] When the short-circuit reference device is measured, the load-reference device is moved to the measurement position and five resistance measurements are performed (step S12). In this way, five measurement values ​​are obtained for each of the short-circuit reference and the load reference (hereinafter referred to as "short-circuit reference measurement value Rms" and "load reference measurement value Rml," respectively).

[0067] The short-circuit reference measurement value Rms and the load reference measurement value Rml (reference measurement value) are temporarily stored in the measurement unit 20 each time they are measured. It should be noted that the order of step S11 and step S12 can also be reversed so that the load reference measurement is performed before the short-circuit reference measurement. In the following, for ease of explanation, the five measurements are assigned measurement numbers n (n = 1 to 5), and the measurement results are indicated by adding the measurement numbers as suffixes in brackets (see Figure 5 ). In addition, hereinafter, the reference value of the short-circuit reference is referred to as “short-circuit reference value Rds”, and the reference value of the load reference is referred to as “load reference value Rd1”.

[0068] After the short-circuit reference measurement value Rms and the load reference measurement value Rml are measured multiple times in the reference measurement step, the calculation step is then performed. In the calculation step, the open-circuit reference measurement value Rmo, the short-circuit reference measurement value Rms, and the load reference measurement value Rml temporarily stored in the measurement unit 20 are first sent to the processing unit 30. In the processing unit 30, the transmission parameter represented by the constant in the above-mentioned formula (2) is calculated based on the open-circuit reference measurement value Rmo, the short-circuit reference measurement value Rms, and the load reference measurement value Rml, and the corresponding open-circuit reference value Rdo, the short-circuit reference value Rds, and the load reference value Rdl.

[0069] Specifically, in the calculation process, first, as shown in step S13, the short-circuit reference measurement value Rms and the load reference measurement value Rml corresponding to the five times are selected one by one to group them, and the transmission parameters corresponding to the five groups are calculated based on each group (a total of five groups) and the open-circuit reference value. For example, in this embodiment, the measurement results of the short-circuit reference and the load reference with the same measurement number are taken as one group, and the transmission parameters of the five quantities (hereinafter referred to as transmission parameters P(1) to P(5)) are calculated (refer to Figure 5 ). It should be noted that the method for selecting a group is not limited to this and can be set arbitrarily.

[0070] Next, as shown in step S14, an arbitrary measurement value (here, Rml(1)) is selected from the five load reference measurement values ​​Rml, and the selected load reference measurement value Rml(1) is corrected using the five transmission parameters P(1) to P(5) to obtain a resistance value. Hereinafter, the resistance value obtained by correction is referred to as the corrected resistance value Rcl. In the case of indicating a corrected resistance value of a specific measurement result, a suffix corresponding to the measurement number is added to indicate it (see Figure 6 It should be noted that P(1) is calculated based on the first load reference measurement value Rml, so the corrected resistance value Rcl(1) obtained by correcting the first load reference measurement value Rml(1) using P(1) is consistent with the load reference value Rdl.

[0071] Next, representative values ​​of the multiple short-circuit reference measurement values ​​Rms and load reference measurement values ​​Rml are calculated based on the corrected resistance value Rcl. In this embodiment, the representative value is the average of the multiple short-circuit reference measurement values ​​Rms and load reference measurement values ​​Rml that meet the specified selection completion condition. The selection completion condition for the representative value is that the distribution statistic of the corrected resistance values ​​Rcl corresponding to any multiple (in this embodiment, three consecutive measurement numbers) load reference measurement values ​​Rml selected from the multiple measurement values ​​meets a threshold. Specifically, in this embodiment, it means that the difference between the maximum and minimum values ​​of the three corrected resistance values ​​Rcl corresponding to the load reference measurement value Rml is less than a difference threshold. The difference threshold here is set based on the degree of deviation in the Q value required for the DUT as a product (as product precision). The difference threshold is set, for example, to 5% of the load reference value Rdl. Furthermore, since the measurement reference value is the corrected resistance value Rcl, rather than the measured value itself (the original value), it is easy to compare with the reference value.

[0072] The acquisition of the representative value is specifically described. In step S15, k, which represents the starting number of the measurement number to be selected, is initialized to 1 as an initial value. In step S16, the difference between the maximum and minimum values ​​of the three corrected resistance values ​​Rcl with measurement numbers k to k+2 is calculated. Then, in step S17, the calculated difference is compared with the difference threshold. When the difference is less than or equal to the difference threshold, it is assumed that the selection completion condition is met, and the process proceeds to step S18. The short-circuit reference measurement value Rms and the load reference measurement value Rml with measurement numbers k to k+2 are averaged to calculate the respective representative values ​​Rms_ave and Rml_ave. Then, in step S19, the transmission parameter is obtained using formula (2) based on the open-circuit reference value Rdo, the open-circuit reference measurement value Rmo, the short-circuit reference value Rds, the representative value Rms_ave of the short-circuit reference measurement value Rms, the load reference value Rdl, and the representative value Rml_ave of the load reference measurement value Rml. The transmission parameter obtained here is the transmission parameter for calibrating the measuring device 10.

[0073] If the selection completion condition is not met in step S17 (i.e., the difference is greater than the difference threshold), the process proceeds to step S20, where the starting number k of the measurement number to be selected is shifted by one (k is incremented by 1), and the target measurement result is updated. Next, in step S21, a determination is made as to whether a measurement result with measurement number k+2 exists. If so, step S16 is repeated.

[0074] If there are no k+2th measurement results in step S21, a new short-circuit benchmark measurement process is performed in step S22, and a new load benchmark measurement process is performed in step S23. When the number of measurement results is incremented by one, step S16 is executed again. For example, if the difference value is not less than or equal to the difference threshold in step S17, the process is repeated. If k reaches 4 in step S20, steps S22 and S23 are executed to obtain the k+2th, or sixth, measurement result, and then step S16 is executed again.

[0075] In this way, the selection of measurement values ​​(k as the measurement number to be selected initially) is changed until a measurement value that satisfies the selection completion condition is selected. In addition, if the number of samples of the measurement results is insufficient, additional measurement results are added, and the difference between the maximum and minimum values ​​is compared with the difference threshold.

[0076] As described above, representative values ​​Rms_ave and Rml_ave, which are average values ​​of the short-circuit reference measurement value Rms and the load reference measurement value Rml, are obtained from the multiple measurements. Based on these representative values ​​Rms_ave and Rml_ave, the transmission parameters for calibrating the measurement device 10 are calculated. The measurement unit 20 is calibrated based on the thus calculated transmission parameters.

[0077] Next, refer to Figure 7 , the maintenance warning process performed by the processing unit 30 is explained.

[0078] The measuring device 10 is configured to execute a maintenance warning process for issuing a warning to urge maintenance of the contact 40 during the execution of the calibration method. The processing unit 30 is configured to execute a maintenance warning process for issuing a warning to urge maintenance of the contact 40 every time the difference between the maximum value and the minimum value of the correction resistance value Rcl is determined to be greater than the difference threshold value (No in step S17) during the calibration method. Figure 7 Maintenance warning procedure shown.

[0079] When the maintenance warning process is to be implemented, if the difference between the maximum and minimum values ​​of the corrected resistance value Rcl is greater than the difference threshold value in step S17 of the calibration method, a series of steps from step S30 to step S33 of the maintenance warning process are executed after step S20, and then step S21 of the calibration method is executed.

[0080] like Figure 7 As shown, in step S30, the difference is compared with a predetermined maintenance threshold. The maintenance threshold is a value greater than or equal to the difference threshold. If it is determined in step S30 that the difference is less than the maintenance threshold, the maintenance warning process is terminated directly.

[0081] If the difference is determined to be greater than the maintenance threshold in step S30, the process proceeds to step S31 where the counter value is incremented by 1. The counter value is initialized to 0 during initial calibration or after maintenance, or is initialized to 0 (zero) by an instruction from the operator's operating unit 80.

[0082] Next, in step S32, a determination is made as to whether the count value has reached a predetermined warning count. If the count value has not reached the warning count, the maintenance warning process is terminated immediately. If the count value has reached the warning count, the process proceeds to step S33, where the processing unit 30 outputs a warning signal to the display unit 70. This causes a warning message urging maintenance of the contact 40 to be displayed on the display unit 70. The warning count value can be arbitrarily set to a number greater than 1, depending on the specifications of the inspection apparatus 100 or the DUT. Alternatively, the count value itself may be displayed instead of or in addition to the warning message.

[0083] As contact 40 wears out, the difference between the reference value and the reference measured value increases. If the large difference between the reference value and the reference measured value persists, there is a possibility that the difference is not due to measurement error but rather to wear of contact 40. Therefore, when the maintenance warning process detects that the difference has reached a maintenance threshold value or greater for a predetermined number of times, a maintenance warning can be issued to urge maintenance of contact 40, enabling efficient calibration of measurement device 10.

[0084] Next, the effects of this embodiment will be described.

[0085] The inductor as the DUT of this embodiment is used, for example, as a bandpass filter in a wireless communication circuit of a mobile device. The bandpass filter is provided in the wireless communication circuit to transmit and receive using a specific frequency band used in wireless communication. For example, in frequency division multiplexing (FDM) in which multiple signals of different frequency bands are transmitted through a transmission line, a bandpass filter is required to avoid signal interference. Generally, if the resistance component R of the inductor is large and the Q value is low, the bandwidth will become larger, and signals of unnecessary frequencies will also be transmitted / received. In recent years, with the increasing demand for products and services that utilize wireless communication, the allocation of frequency bands has become increasingly urgent. In response to this situation, in order to increase the precision of the bandpass filter, the demand for inductors with high Q values ​​has increased dramatically.

[0086] In addition, if the resistance component R of the inductor is small, the energy loss in the inductor can also be reduced. In wireless communications, if the energy loss is reduced, the components and equipment can be miniaturized due to reduced heat generation, and the battery consumption can be suppressed, thereby extending the driving time. In addition, the output power of the signal can be increased. If the output power of the signal is increased, the amplification rate of the signal can be suppressed, and the noise associated with the amplification of the signal can be reduced. This energy loss problem is not limited to communication technology, but also occurs in other technical fields such as power transmission. Therefore, in various technical fields, there is a demand to improve the Q value of the inductor.

[0087] On the other hand, in measurement devices that measure electrical characteristics, measurement errors may occur due to the transmission characteristics of the electrical signal transmission path from the measurement unit that inputs and outputs the electrical signal to the object being measured. Therefore, to eliminate the influence of the transmission characteristics of the transmission path on measurement errors, measurement devices are calibrated before measuring the object being measured.

[0088] As a method for calibrating a measuring device, there is known a method in which the measuring device measures the electrical characteristics of a reference object (reference device) with known electrical characteristics to obtain transmission parameters representing the characteristics of a transmission path, and performs calibration using the transmission parameters.

[0089] In this calibration method, the transmission parameters are obtained based on the electrical characteristics measured by bringing the contactor of the measuring device into contact with a reference object. Therefore, if the contact state (contact resistance) between the contactor and the reference object is different, the value of the transmission parameter will vary, resulting in measurement error.

[0090] Typically, the impact of measurement error on calibration of measurement equipment is minimal, and therefore, has not been considered in the past. However, as mentioned above, with the recent demand for higher functionality and smaller electronic components, there is a growing demand for higher precision in the electrical characteristics of these components. Therefore, there is a need to reduce measurement error during calibration of measurement equipment.

[0091] According to this embodiment, characteristic parameters are calculated based on representative values ​​(Rms_ave, Rml_ave) of reference measurement values ​​(short-circuit reference measurement value Rms, load reference measurement value Rml) obtained by measuring the reference multiple times. Therefore, even if there is a deviation in the contact state between the contact 40 and the reference, characteristic parameters close to the true value can be obtained. From another point of view, by using representative values ​​(average values) of multiple reference measurement values, characteristic parameters are calculated taking into account the deviation in the contact state between the contact 40 and the reference. Therefore, even if there is a deviation in the contact state during the actual measurement (DUT inspection) performed by the measurement device 10, a high-precision measurement closer to the true value can be performed. As described above, the measurement error caused by calibration can be reduced, and the electrical characteristics and the DUT inspection can be performed with high precision.

[0092] Furthermore, in this embodiment, a representative value of the reference measurement value is calculated based on the equivalent series resistance, and the characteristic parameter is calculated based on the corresponding representative value. Since the equivalent series resistance is affected by the contact resistance, the characteristic parameter can be obtained by obtaining a representative value based on the equivalent series resistance that takes into account the variation in the contact resistance.

[0093] Furthermore, according to this embodiment, a maintenance warning process is executed using the difference between the maximum and minimum values ​​of the corrected resistance value Rcl calculated during the calibration method. This maintenance warning process prompts maintenance of the contact 40, eliminates deviations in measured values ​​caused by wear of the contact 40, and enables efficient calibration of the measuring device 10.

[0094] Next, a modification of this embodiment will be described.

[0095] In the above embodiment, a representative value of the reference measurement value is obtained based on the result of comparing the difference between the maximum and minimum values ​​of the three selected correction resistance values ​​with a difference threshold, more specifically, based on the measurement result that the difference is less than or equal to the difference threshold. However, the method for obtaining the representative value is not limited to this configuration and can be set arbitrarily. For example, the change in the average value resulting from adding one to the measurement value used in the average calculation can be compared with a predetermined threshold. If the change in the average value is less than or equal to the threshold, the average value is used as the representative value of the measurement reference value.

[0096] To explain specifically, first, the average value of j measurement values ​​(for example, two measurement values, measurement numbers 1 and 2) as the initial setting number is calculated. Next, one measurement result is added to obtain the average value of j+1 (three measurement values, 1 to 3), and the difference between the average value of j and the average value of j+1 is calculated. Then, when the difference in the average values ​​is less than or equal to the judgment threshold, the average value of j+1 measurement results is obtained as the representative value. When the difference in the average values ​​is greater than the judgment threshold, one is added to the measurement result to obtain the average value of j+2 measurement results. Then, the difference between the average value of j+1 measurement values ​​and the average value of j+2 measurement results is calculated and compared with the judgment threshold again. In this way, the representative value can also be obtained by comparing the difference between the average value of j measurement values ​​and the average value of j+1 with the judgment threshold, and the transmission parameter is calculated based on the representative value. In addition, when the representative value is obtained based on the change in the average value, a maintenance threshold is set for the value of the change in the average value to perform a maintenance warning process.

[0097] In addition, in the above-mentioned embodiment and modification, the following configuration is used: a comparison is performed between the difference between the maximum and minimum values ​​of the corrected resistance value Rcl and the difference threshold value, or a comparison is performed between the change in the average value and the judgment threshold value. If the comparison result does not meet the prescribed end condition, a new reference measurement process is executed to increase the number of measurement results. In contrast, the configuration of executing the reference measurement process when the prescribed end condition is not met is not a necessary configuration. For example, when multiple (five as an example) reference measurement values ​​are obtained, the average value of these measurement values ​​is used as a representative value, and the characteristic parameters are obtained based on the representative value. In this case, the measurement error caused by the correction can also be reduced, and the electrical characteristics can be measured and the DUT can be inspected with high precision.

[0098] In addition, in the above-mentioned embodiment and modification, a plurality of (five) reference measurement values ​​are obtained in advance, and if the prescribed end condition is not satisfied according to these reference measurement values, a new measurement is performed. In this way, by initially pre-measuring a plurality of reference measurement values, the movement (replacement) of the reference devices of the short-circuit reference and the load reference is reduced, so that the correction method can be carried out efficiently. In contrast, it can also be set as follows: the reference measurement process is performed once for each of the short-circuit reference and the load reference, and a determination is made whether the end condition is satisfied each time the process is performed. In addition, it can also be set as follows: the reference measurement process is performed multiple times in advance for one of the short-circuit reference and the load reference, and an end determination is made each time the reference measurement process of the other is performed.

[0099] Furthermore, in the above-described embodiment, the corrected resistance value Rcl is calculated based on the load reference measurement value Rml, and the measurement result used to obtain the representative value is selected based on the difference between the maximum and minimum values ​​of the multiple corrected resistance values ​​Rcl. Using the load reference measurement value Rml, which is closer to the actual measured DUT resistance value than the open-circuit reference and short-circuit reference values, allows the measurement device 10 to be calibrated according to the deviation of the measured values ​​during actual DUT inspection. Therefore, the measurement device 10 can be calibrated with higher accuracy. However, using the load reference measurement value Rml is not essential; the corrected resistance value can also be calculated based on the short-circuit reference measurement value Rms to calculate the representative value, and further calculate the characteristic parameters to calibrate the measurement device 10.

[0100] The calibration method of the above embodiment calibrates the measuring device 10 based on the measurement reference values ​​of the open reference, short reference, and load reference. However, the calibration method may also be so-called open / short calibration that performs calibration based on the open reference and the short reference.

[0101] Furthermore, in the above embodiment, the average value is calculated as the representative value of the measurement reference value, but the representative value may be another value obtained from a plurality of measurement reference values, such as the median.

[0102] Furthermore, in the above-described embodiment, the plurality of measurement values ​​temporarily stored in the measurement unit 20 are output to the processing unit 30, and the representative value of the measurement reference value and the characteristic parameter are calculated in the processing unit 30. Alternatively, the representative value of the measurement reference value may be calculated in the measurement unit 20, and the characteristic parameter may be calculated based on the representative value in the processing unit 30. Furthermore, the measurement unit 20 may output a measurement value to the processing unit 30 each time a measurement is performed, without temporarily storing the plurality of measurement values.

[0103] Furthermore, the measurement performed by the measurement unit 20 is not limited to the two-terminal measurement method or the four-terminal measurement method, and other measurement methods such as the five-terminal measurement method or the six-terminal measurement method may be employed.

[0104] Hereinafter, the configuration and effects of each embodiment will be summarized and described.

[0105] The inspection method of this embodiment includes a calibration step for calibrating the measurement device 10, and an inspection step for inspecting the DUT using the measurement device 10. The calibration method performed in the calibration step includes an open-circuit reference measurement step for measuring electrical characteristics in an open-circuit state where the contact 40 is not in contact with any other object to obtain an open-circuit reference measurement value Rmo; a reference measurement step for bringing the contact 40 into contact with a reference object with known electrical characteristics to measure the reference object's electrical characteristics; and a calculation step for calculating a transmission parameter representing the characteristics of the transmission path from the measurement unit 20 to the object based on the open-circuit reference measurement value Rmo, a reference value representing the known electrical characteristics of the reference object, and a measurement reference value representing the result of measuring the electrical characteristics of the reference object. The reference measurement step is performed multiple times by repeatedly bringing the contact 40 into contact with and separating from the reference object. In the calculation step, a representative value of the measurement reference value is obtained from the multiple measured measurement reference values, and the transmission parameter is calculated based on the representative value of the measurement reference value.

[0106] Furthermore, the inspection apparatus 100 of the present embodiment includes the measuring apparatus 10 , and the processing unit 30 of the measuring apparatus 10 is configured to be able to execute the above-described calibration method.

[0107] In addition, in the correction method of this embodiment, the representative value is the average value of the multiple measured reference values. In the calculation process, the difference between the maximum value and the minimum value of the multiple measurement reference values ​​is obtained, and the transmission parameter is calculated based on the result of comparing the difference with a predetermined judgment threshold. The reference measurement process is re-executed based on the comparison result of the difference between the measurement reference values ​​in the calculation process and the judgment threshold.

[0108] In addition, in the correction method of a variant example of the present embodiment, the representative value is the average value of multiple measured measurement reference values. In the calculation process, after the reference measurement process is executed a specified number of times or more, the average value of the newly acquired measurement reference value is calculated each time the reference measurement process is executed, and the transmission parameter is calculated based on the result of comparing the change in the average value of the measurement reference value accompanying the newly executed reference measurement process with a predetermined judgment threshold. The reference measurement process is re-executed based on the result of comparing the change in the average value of the measurement reference value in the calculation process with a predetermined judgment threshold.

[0109] In this embodiment, characteristic parameters are calculated based on representative values ​​of measurement reference values ​​obtained by multiple measurements of the reference object. Therefore, even if the contact state between the contactor 40 and the reference object deviates, characteristic parameters close to the true value can be obtained. This reduces measurement errors caused by calibration.

[0110] In addition, the calibration method of this embodiment further includes: a maintenance warning process, which compares the difference between the maximum and minimum values ​​of the measurement reference value with the maintenance threshold, and issues a warning urging maintenance when the difference is greater than or equal to the maintenance threshold a specified number of times.

[0111] In this configuration, the maintenance warning process is executed using the difference between the maximum and minimum measurement reference values ​​calculated during the calibration process. This maintenance warning process prompts maintenance of the contact 40, eliminates deviations in measurement values ​​caused by wear of the contact 40, and allows for efficient calibration of the measuring device 10.

[0112] While the embodiments of the present invention have been described above, the above embodiments merely illustrate a part of application examples of the present invention and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments.

[0113] A part or all of the processing unit 30 of the measurement device 10 may be configured as a cloud server provided in a cloud environment.

[0114] Furthermore, the series of processes in the processing unit 30 described above may be provided as a program for causing a computer to execute the series of processes.

[0115] That is, the program of the above-mentioned embodiment causes the processing unit 30 of the computer serving as the measuring device 10 to perform the following steps: measuring the electrical characteristics in an open circuit state in which the contact 40 is not in contact with other objects to obtain an open circuit reference measurement value; bringing the contact 40 into contact with a reference object with known electrical characteristics to measure the electrical characteristics of the reference object to obtain a measurement reference value; calculating a transmission parameter representing the characteristics of the transmission path between the measuring unit and the object based on the open circuit reference measurement value, the reference value of the known electrical characteristics possessed by the reference object, and the measurement reference value obtained by measuring the electrical characteristics of the reference object; the step of obtaining the measurement reference value is performed multiple times in a manner that causes the contact 40 to repeatedly contact the reference object; in the step of calculating the transmission parameter, a representative value of the measurement reference value is obtained based on the multiple measurement reference values, and the transmission parameter is calculated based on the representative value of the measurement reference value.

[0116] In addition, the program for executing the above-mentioned series of processing is provided via a storage medium readable by the processing unit 30. In addition, the program can also be provided to the processing unit 30 via a network line.

Claims

1. A calibration method, which is a calibration method for a measuring device, wherein: The measuring device comprises: a contact head, which contacts an object; and a measuring unit configured to measure an electrical characteristic of the object based on an electrical signal applied to the object, wherein the calibration method includes: an open circuit reference measurement step of measuring the electrical characteristics in an open circuit state in which the contact is not in contact with other objects to obtain an open circuit reference measurement value; a reference measuring step of bringing the contact into contact with a reference object with known electrical characteristics to measure the electrical characteristics of the reference object; and a calculation step of calculating a transmission parameter representing a characteristic of a transmission path from the measuring unit to the object based on the open circuit reference measurement value, a reference value representing the known electrical characteristic of the reference object, and a measurement reference value representing a result of measuring the electrical characteristic of the reference object; The reference measurement step is performed multiple times by repeatedly bringing the contactor into contact with and separating from the reference object. In the calculation process, acquiring a representative value of the measurement reference value based on the plurality of measured measurement reference values; The transmission parameter is calculated based on the representative value of the measurement reference value.

2. The calibration method according to claim 1, wherein: The representative value is an average value of a plurality of the measured reference values. In the calculation step, the difference between the maximum value and the minimum value of the plurality of measurement reference values ​​is obtained, and the transmission parameter is calculated based on the result of comparing the difference with a predetermined judgment threshold value. The reference measurement step is re-executed based on a comparison result between the difference between the measurement reference value and the determination threshold value in the calculation step.

3. The calibration method according to claim 2, further comprising: The maintenance warning step compares the difference between the maximum and minimum values ​​of the measurement reference values ​​with a maintenance threshold value, and issues a warning urging maintenance when the difference is greater than or equal to the maintenance threshold value a predetermined number of times.

4. The calibration method according to claim 1, wherein: The representative value is an average value of a plurality of the measured reference values. In the calculation process, After the reference measurement step is executed two or more times, each time the reference measurement step is executed, an average value including the newly acquired measurement reference value is calculated; calculating the transmission parameter based on a result of comparing a change in the average value of the measurement reference value associated with a new execution of the reference measurement step with a predetermined determination threshold; The reference measurement step is re-executed based on a comparison result of a change in the average value of the measurement reference values ​​in the calculation step and the predetermined determination threshold value.

5. A measuring device comprising: Contact, which comes into contact with the object; a measuring unit that brings the contact into contact with the object and measures electrical characteristics of the object through the contact; as well as a processing unit that processes the measurement results obtained by the measurement unit, The processing unit is configured to perform the following steps: measuring the electrical characteristics in an open circuit state where the contact is not in contact with other objects to obtain an open circuit reference measurement value; bringing the contact into contact with the reference object having known electrical characteristics to measure the electrical characteristics of the reference object and obtain a measurement reference value; as well as calculating a transmission parameter representing a characteristic of a transmission path between the measuring unit and the object based on the open circuit reference measurement value, a reference value of the known electrical characteristic of the reference object, and the measurement reference value obtained by measuring the electrical characteristic of the reference object; The step of obtaining the measurement reference value is performed multiple times in such a manner that the contactor repeatedly contacts the reference object. In the step of calculating the transmission parameter, a representative value of the measurement reference value is acquired based on the plurality of measurement reference values, and the transmission parameter is calculated based on the representative value of the measurement reference value.

6. A method for inspecting an inductor using a measuring device, wherein: The measuring device includes: a contactor that contacts the inductor as an object; and a measuring unit configured to measure electrical characteristics of the inductor based on an electrical signal applied to the inductor, wherein the inspection method includes: a calibration step of acquiring a transmission parameter indicating a characteristic of a transmission path between the contactor and the measurement unit of the measurement device, and calibrating the measurement device based on the transmission parameter; and an inspection step of bringing the contactor into contact with the inductor to measure the electrical characteristics and inspect whether the inductor is in good condition; The correction process includes: an open circuit reference measurement step of measuring the electrical characteristics in an open circuit state in which the contact is not in contact with other objects to obtain an open circuit reference measurement value; a reference measurement step of bringing the contact into contact with a reference object with known electrical characteristics to measure the electrical characteristics of the reference object and obtain a measurement reference value; and a calculation step of calculating the transmission parameter representing the characteristics of the transmission path from the measuring portion to the contact based on the open circuit reference measurement value, the reference value of the known electrical characteristic of the reference object, and the measurement reference value obtained by measuring the electrical characteristic of the reference object; The reference measurement step is performed multiple times in such a manner that the contactor repeatedly contacts the reference object. In the calculation process, obtaining a representative value of the measurement reference value based on the measurement reference value measured a plurality of times, The transmission parameter is calculated based on the representative value of the measurement reference value.

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