Inspection apparatus, inspection method, capacitor manufacturing method, and inspection program product

Abstract

Provided is an inspection device, an inspection method, a capacitor manufacturing method, and an inspection program product that exclude a chip capacitor having a possibility of short life that cannot be detected in a conventional insulation resistance measurement. The inspection device includes: a current measurement unit that measures a current during a charging period of a chip capacitor and a current during an insulation resistance measurement period after the charging period; a voltage measurement unit that measures a voltage applied to the chip capacitor during the charging period and the insulation resistance measurement period; and a determination unit that determines whether the chip capacitor is acceptable based on whether either of the current measured by the current measurement unit and the voltage measured by the voltage measurement unit during the charging period and the insulation resistance measurement period satisfies a threshold value decided in advance.

Description

Technical Field

[0001] This disclosure relates to inspection apparatus, inspection methods, methods for manufacturing capacitors, and inspection procedures for products. Background Technology

[0002] Traditionally, the following method has been used to screen multilayer ceramic capacitors (MLCCs) and other surface-mount capacitors for quality control: a specified voltage is applied to the capacitor for constant current charging; after a certain period of time following the attainment of the specified voltage, the leakage current flowing through the capacitor is measured; and products exceeding the specified current value are rejected. However, it is well known that among surface-mount capacitors deemed acceptable (good), i.e., those with leakage current below the specified value, a small number are electronic components with short lifespans. How to exclude these short-lifespan capacitors from the acceptable range has become a major quality management problem. The phenomenon of shortened lifespan despite having insulation resistance equivalent to acceptable products (e.g., electrical characteristics deteriorating earlier than expected) is often attributed to internal cracks.

[0003] When a specified voltage is applied to a surface-mount capacitor, a current limiter (e.g., around 30mA to 50mA) is included in the power supply used for voltage application, and the power supply performs constant current charging at its current value. For film capacitors, the voltage rises linearly due to constant current charging; however, surface-mount capacitors exhibit voltage dependence due to their electrostatic capacitance (higher voltage results in lower capacitance), thus the voltage rise curve is curved. There are methods for monitoring sharp voltage drops by observing this curve and the voltage after charging (Patent Document 1).

[0004] For example, when a brief insulation failure occurs and it self-repairs, a spike-like voltage drop occurs, and methods exist to detect this. Specifically, at the site of the insulation failure, the voltage drops momentarily due to the discharge current (larger than that of a current limiter). However, as the damaged area is burned through by this discharge energy and separated from its surroundings, it self-repairs, and the voltage rises back to normal. However, the repaired area may develop defects such as cracks, potentially leading to a shortened lifespan. Therefore, detecting this spike-like voltage drop can help screen for products with short lifespans.

[0005] In addition, there is a method to monitor spike-like current increases by observing the leakage current flowing through a surface-mount capacitor after applying a specified voltage. Similar to voltage, when a temporary insulation failure occurs in a surface-mount capacitor, the leakage current increases. However, due to the impact of heat generation and other shocks caused by this increased current, the leakage current recovers to its original normal value. Likewise, the repaired current may become a crack or other defect, potentially leading to a shortened lifespan. Therefore, it is also possible to detect products with short lifespans by detecting this current increase.

[0006] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2000-228338. Summary of the Invention

[0007] The problem the invention aims to solve In cases of insulation damage with voltage fluctuations, the current flowing through the plate capacitor may sometimes exceed the power supply's limiting current, but due to the extent of the insulation damage, this large current may not flow. In other words, with minor insulation damage, the voltage may not change or may change only slightly; therefore, the aforementioned inspection method based on observing the voltage may fail to detect the defect.

[0008] Furthermore, in the latter method of observing the spike-like rise of leakage current, when the normal current supplied to the plate capacitor is large, such as during the initial charging stage, it exceeds the maximum value of the ammeter's measurement range, thus making it impossible to measure the current. When the current reading exceeds the maximum value of each range, it is in a saturation state, making it impossible to determine whether the current value is abnormal, thus making accurate measurement impossible.

[0009] Furthermore, since the initial leakage current flowing through a chip capacitor is mostly due to dielectric absorption, it decreases over time. After a certain period, the saturation of the current reading disappears, making current measurement possible. However, since current value cannot be measured (acquired) during the period when the current reading saturates after voltage is applied, current anomalies cannot be detected during this period. Additionally, the normal period for measuring the insulation resistance of a chip capacitor occurs after a spike in voltage or current, during which spikes cannot be detected.

[0010] The purpose of this disclosure is to provide an inspection apparatus, inspection method, capacitor manufacturing method, and inspection procedure product for surface-mount capacitors that have the potential to have a short lifespan but cannot be detected in conventional insulation resistance measurements.

[0011] Solution for solving the problem The inspection apparatus disclosed herein includes: a current measuring unit that measures the current during charging of a surface-mount capacitor and the current during insulation resistance measurement after the charging period; a voltage measuring unit that measures the voltage applied to the surface-mount capacitor during the charging period and the insulation resistance measurement period; and a determination unit that determines whether the surface-mount capacitor is qualified based on whether either the current measured by the current measuring unit or the voltage measured by the voltage measuring unit during the charging period and the insulation resistance measurement period meets a predetermined threshold.

[0012] The inspection method disclosed herein includes the following steps: measuring the current during the charging period of a chip capacitor and the current during the insulation resistance measurement period after the charging period by a current measuring circuit; measuring the voltage applied to the chip capacitor during the charging period and the insulation resistance measurement period by a voltage measuring circuit; and determining whether the chip capacitor is qualified by a determination circuit based on whether either the current measured by the current measuring circuit or the voltage measured by the voltage measuring circuit during the charging period and the insulation resistance measurement period meets a predetermined threshold.

[0013] The capacitor manufacturing method disclosed herein includes the following steps: measuring the current during charging of a chip capacitor and the current during insulation resistance measurement after the charging period by a current measuring circuit; measuring the voltage applied to the chip capacitor during the charging period and the insulation resistance measurement period by a voltage measuring circuit; and determining whether the chip capacitor is qualified by a determination circuit based on whether either the current measured by the current measuring circuit or the voltage measured by the voltage measuring circuit during the charging period and the insulation resistance measurement period meets a predetermined threshold.

[0014] The inspection procedure disclosed herein is an inspection procedure product including an inspection procedure, wherein the inspection procedure, when executed by a computer processor, includes the following functions: measuring the current during charging of a chip capacitor and the current during insulation resistance measurement after the charging period by a current measuring circuit; measuring the voltage applied to the chip capacitor during the charging period and the insulation resistance measurement period by a voltage measuring circuit; and determining whether the chip capacitor is qualified by a determination circuit based on whether either the current measured by the current measuring circuit and the voltage measured by the voltage measuring circuit during the charging period and the insulation resistance measurement period meets a predetermined threshold.

[0015] The effects of the invention According to this disclosure, an inspection apparatus, inspection method, capacitor manufacturing method, and inspection procedure product can be provided to eliminate the possibility of short lifespan in surface-mount capacitors that cannot be detected in conventional insulation resistance measurements. Attached Figure Description

[0016] Figure 1 This is a front view of the electronic component screening device.

[0017] Figure 2 This is a schematic diagram of the conveying components.

[0018] Figure 3 This diagram illustrates the operation of the conveying components and measuring terminals during the transport and measurement of a surface-mount capacitor.

[0019] Figure 4 This is a block diagram of the inspection device.

[0020] Figure 5 This is a graph showing the voltage and current waveforms of the plate capacitor under measurement. Detailed Implementation

[0021] The embodiments of this disclosure are described below with reference to the accompanying drawings. Figure 1 The electronic component screening device 1 (inspection and screening device) shown is a characteristic screening machine that inspects the electrical characteristics of chip capacitors C (electronic components) that have electrodes at least on their sides or a portion of their planes, and classifies them according to the inspection results. The chip capacitor C in this embodiment is a multilayer ceramic capacitor. The chip capacitor C has a cuboid shape with dimensions such as length L > width W = thickness T, or length L > width W > thickness T, set to design dimensions. The chip capacitor C can be used with so-called two-terminal capacitors, three-terminal capacitors, multi-terminal capacitors, or array capacitors, etc., having end-face electrodes, side electrodes, or both.

[0022] Figure 1 This is a schematic front view of the electronic component sorting device 1. The electronic component sorting device 1 includes: a supply unit 12, which supplies a chip capacitor C to a circular plate-shaped conveying member 2 (see reference 1). Figure 2 The circular plate-shaped conveying member 2 is supported so that it can rotate relative to the base portion 111 provided on the device body 11, which is generally rectangular in shape; the conveying portion 13 conveys the plate capacitors C supplied by the supply portion 12 by rotating the conveying member 2; the inspection portion 14 inspects the electrical characteristics (insulation resistance, withstand voltage, electrostatic capacitance, etc.) of the plate capacitors C conveyed by the conveying member 2 in the conveying portion 13; and the sorting and discharge portion 15 sorts and discharges the plate capacitors C according to the inspection results of the inspection portion 14.

[0023] Figure 2This is a schematic diagram of the conveying member 2. The conveying member 2 temporarily houses and conveys the chip capacitor C. The conveying member 2 has multiple receiving holes 21 (also called chip capacitor receiving and holding holes, pouches, or through holes) on the circumference of the rotation axis P. The receiving holes 21 are arranged in multiple columns around the rotation axis P. Figure 2 The conveying member 2 is shown as an example with eight rows of receiving holes 21a~21h (enlarged view of part A), but the receiving holes 21 can also be composed of other multiple rows such as six, ten or twelve.

[0024] In this embodiment, the receiving hole 21 is a through hole. Regarding the receiving hole 21, depending on the shape of the chip capacitor C and the inspection method of the inspection section 14, a rectangular hole or a circular hole can be used. Most of the opening of the receiving hole 21 on the base section 111 side is blocked by the base section 111, and when the conveying member 2 is installed on the base section 111, the receiving hole 21 is configured as a bottomed shape. The receiving hole 21 is attracted by the vacuum groove formed in the base section 111, thus enabling stable reception and conveying of the chip capacitor C. In this embodiment, the chip capacitor C is received relative to the receiving hole 21 in the end direction (length direction) (see also...). Figure 3 ).

[0025] The conveying component 2 is driven by a rotary drive device 112 (see reference 112) located on the base 111 side. Figure 1 It rotates intermittently (or in steps) around the axis of rotation P. Figure 1 In the front view, the conveying member 2 rotates clockwise around the rotation axis P. The electronic component sorting device 1 conveys the plate capacitors C supplied by the supply unit 12 to the conveying member 2 in the order of inspection unit 14 and sorting and discharge unit 15.

[0026] The supply unit 12 includes a hopper unit 121, a feeder 122 that transports the sheet capacitors C supplied from the hopper unit 121, an emitter 123 that supplies the sheet capacitors C supplied from the feeder 122 to the bucket 124 via a transport path (not shown in detail), and a bucket 124 that supplies the sheet capacitors C supplied to the emitter 123 to the receiving hole 21 of the transport member 2.

[0027] The hopper section 121 stores the chip capacitors C before inspection and transports them to the feeder 122 (parts feeder). The hopper section 121 is a silo with an inverted triangular shape when viewed from the top down, as its inner diameter decreases from top to bottom.

[0028] The feeder 122 in this embodiment is a linear feeder with a straight, recessed conveying path on its upper surface. The plate capacitor C is supplied to the transmitter 123 by vibrating the conveying path.

[0029] The transmitter 123 has multiple linear transport paths internally divided by partition walls. The transmitter 123 of this embodiment has eight transport paths. These transport paths are cylindrical passages arranged parallel to each other. The chip capacitor C supplied from the feeder 122 is supplied to which transport path in the transmitter 123, for example, by a distribution mechanism provided on the inlet side of the transmitter 123.

[0030] The bucket 124 supplies the plate capacitors C supplied from the launcher 123 to the receiving holes 21 of the conveying member 2. The bucket 124 is disposed on the front side of the conveying member 2. The bucket 124 has multiple conveying paths divided according to each row of receiving holes 21 (21a~21h) of the conveying member 2. Each conveying path extends parallel to the arrangement direction (circumferential direction) of the receiving holes 21 about the rotation axis P. By generating a negative pressure in the receiving holes 21 via the base portion 111, the plate capacitors C supplied from the launcher 123 to the bucket 124 in the conveying path are received one by one into the receiving holes 21.

[0031] Furthermore, the conveying path of the launcher 123, the conveying path of the bucket 124, and the measuring terminals 141, 142 of the measuring station described later are configured with the same number of rows as the receiving hole 21 (e.g., six rows, ten rows, or twelve rows, or other multiple rows).

[0032] The inspection section 14 has measuring terminals 141 and 142 (contacts) for measuring electrical characteristics at positions near the base portion 111 and the opposite side of each receiving hole 21 of the conveying member 2 (see reference). Figure 3 The measuring terminals 141 and 142 are electrically connected to the inspection device 3 mounted on the electronic component screening device 1 (see reference). Figure 4 ).

[0033] Furthermore, the electronic component sorting device 1 includes a control device 113 that supplies control signals related to measurement processing to the inspection device 3. The control device 113 controls the operation of each functional unit of the electronic component sorting device 1 (supply unit 12, conveying unit 13, inspection unit 14, and sorting and discharge unit 15, etc.), acquires detection values ​​detected by various sensors, and makes judgments. The control device 113 is, for example, the control unit of a personal computer, and is installed within the electronic component sorting device 1. The control device 113 includes a control unit (i.e., processor) such as a CPU, a storage unit (i.e., storage medium) for storing data and programs, an input unit (e.g., touch panel, keyboard, switch, etc.), an output unit (e.g., display, indicator, sound playback unit, etc.), and a communication unit (e.g., a wired or wireless data communication unit).

[0034] The sorting and discharge unit 15 has the function of discharging the plate capacitors C of the conveying member 2 into the recycling container 16 (also called the sorting box) according to the inspection results of the inspection unit 14. The sorting and discharge unit 15 has discharge paths 151 corresponding to each sorting item at different angular positions on the conveying path about the rotation axis P. The discharge path 151 is connected to the recycling container 16 corresponding to the sorting items, which include qualified and unqualified products.

[0035] The discharge path 151 is a cylindrical member formed of resin or metal. Additionally, the sorting discharge section 15 has an exhaust port on the side near the base section 111. When the chip capacitor C is located in the discharge path 151 connected to the recycling container 16 for the discharged object, the sorting discharge section 15 can sort and recycle the chip capacitor C into the recycling container 16 corresponding to the inspection results by switching the compressed air from the exhaust port of the base section 111 to ON.

[0036] Next, the inspection device 3 will be described in detail. Although the inspection device 3 is mainly used to inspect insulation characteristics, it can also be used to inspect withstand voltage characteristics as long as it can measure the current obtained by applying voltage and determine whether the chip capacitor C is qualified (good or defective, etc.). The inspection device 3 is not limited to any particular purpose or name as long as it has the functions of this embodiment.

[0037] The inspection device 3 includes a power supply device 31 and a measuring device 32. The power supply device 31 generates a DC voltage and supplies the DC voltage to the measuring device 32. The measuring device 32 applies the DC current supplied from the power supply device 31 to the surface-mount capacitor C to measure the current and the resistance of the surface-mount capacitor C, and determines whether it is qualified.

[0038] The power supply unit 31 generates a voltage to be applied to the chip capacitor C, which is the device under test (DUT). The power supply unit 31 includes a rectifier circuit 311, a filter circuit 312, a constant voltage circuit 313, a constant current circuit 314, an output resistor 315, and an interlocking relay SW1.

[0039] The power supply voltage from the electronic component screening device 1 to the power supply device 31 via its internal power circuit is rectified by the rectifier circuit 311 and smoothed by the filter circuit 312. The output of the filter circuit 312 is adjusted to a constant voltage and current by the constant voltage circuit 313 and the constant current circuit 314, respectively, and supplied to the measuring device 32 via the output resistor 315 and the interlocking relay SW1.

[0040] The measuring device 32 includes a current measuring unit 321, a differential waveform detection unit 322, a voltage measuring unit 323, a control unit 324, a judgment unit 325, a storage unit 326, and a communication unit 327. Furthermore, as a circuit structure, the measuring device 32 includes an input terminal T0 for supplying power from the power supply unit 31, a voltage application relay SW2, a polarity switching switch SW3, a first terminal T1, a second terminal T2, and a protection resistor R.

[0041] The measuring device 32 outputs the voltage generated by the power supply device 31 from the first terminal T1 via the input terminal T0, the voltage application relay SW2, and the polarity switching switch SW3, and applies this voltage to the surface-mount capacitor C. The current flowing through the surface-mount capacitor C is input from the second terminal T2 and input to the current measuring unit 321 via the polarity switching switch SW3 and the protection resistor R. The current measuring unit 321 is a current measuring circuit that measures the current flowing through the surface-mount capacitor C.

[0042] The polarity switching switch SW3 has the function of changing the polarity of the electrical path connected to the surface capacitor C by changing the connection of the first terminal T1 and the second terminal T2, thereby applying a voltage with the opposite polarity. The user can arbitrarily set the polarity change in advance according to the inspection items of the surface capacitor C.

[0043] Furthermore, the voltage measuring unit 323 is connected in the electrical path between the voltage application relay SW2 and the polarity switching switch SW3. The voltage measuring unit 323 is a voltage measuring circuit that measures the voltage applied to the surface capacitor C. The outputs of both the current measuring unit 321 and the voltage measuring unit 323 are connected to the differential waveform detection unit 322.

[0044] The differential waveform detection unit 322 calculates the output values ​​of the current measuring unit 321 and the voltage measuring unit 323 and outputs the differential value.

[0045] The determination unit 325 acquires the detection values ​​(current value, voltage value and their differential values) detected by the current measuring unit 321, voltage measuring unit 323 and differential waveform detection unit 322, compares them with a predetermined threshold, and determines whether the chip capacitor C is qualified based on whether the threshold is met.

[0046] For example, if the differential value detected by the differential waveform detection unit 322 is large, the size or rate of change (the amount of change per unit time) of the peak waveform is significantly large. If it is larger than a preset threshold, it is judged as unqualified, thus determining whether it is qualified. The differential value can be performed analogically or digitally by processing the data acquired by the A / D converter. The determination unit 325 can detect the peak waveform of the current detected by the current measuring unit 321 or the voltage detected by the voltage measuring unit 323.

[0047] The control unit 324 executes functions and / or methods implemented by the code or commands included in the program stored in the storage unit 326. As examples, the control unit 324 can utilize a central processing unit (CPU), MPU (Micro-Processing Unit), GPU, MCU (Microcontroller Unit), processor core, multiprocessor, ASIC, FPGA, etc., and can also implement the various processes disclosed in this embodiment through logic circuits or dedicated circuits formed in integrated circuits, etc. Furthermore, these circuits can be implemented by one or more integrated circuits, and the multiple processes shown in each embodiment can also be implemented by a single integrated circuit.

[0048] The control unit 324 controls the operation of each functional unit (judgment unit 325, storage unit 326, communication unit 327, etc.) of the measuring device 32, and processes the judgment results of the detection values ​​detected by various detection units (current measuring unit 321, differential waveform detection unit 322, voltage measuring unit 323, etc.). The communication unit 327 communicates with the control device 113 and other devices via wired or wireless means.

[0049] The control device 113 is, for example, the control unit of a personal computer, and is installed in the electronic component screening device 1. The control unit 324 is installed in the inspection device 3 (power supply device 31, measuring device 32).

[0050] In addition, the measuring device 32 may also include an input unit (e.g., a touch panel, keyboard, switch, etc.) and an output unit (e.g., a display, indicator, sound playback unit, etc.).

[0051] Next, the inspection method performed by the inspection device 3 and the manufacturing method of the chip capacitor C manufactured by performing the inspection method will be described.

[0052] exist Figure 1 In the electronic component screening device 1, the chip capacitor C fed in via the supply unit 12 is housed in the receiving hole 21 of the conveying member 2 rotatably mounted on the conveying unit 13 (see reference). Figure 2 In the process, along with the intermittent rotation of the conveying component 2, Figure 1 The capacitor moves clockwise around the rotation axis P. The plate capacitor C is first moved to the inspection section 14.

[0053] Figure 3 This diagram illustrates the operation of the conveying member 2 and the measuring terminals 141 and 142 during the conveying and measuring of the chip capacitor C. Figure 3The diagram shows measurement terminals 141 and 142 of a measurement station disposed in the inspection unit 14. The inspection unit 14 of this embodiment includes: a fixed measurement terminal 142 having a contact surface substantially flush with the surface of the base portion 111; and a measurement terminal 141 disposed opposite to the measurement terminal 142. A probe terminal is used as the measurement terminal 141.

[0054] The inspection unit 14 is equipped with multiple testing stations along the conveying direction (the rotation direction of the conveying member 2) to perform multiple inspections on the plate capacitor C moving in the conveying direction. Each testing station is equipped with... Figure 3 The measurement terminals 141 and 142 are shown.

[0055] As an example of a structure with multiple testing stations, the following configuration is provided: four stations (hereinafter referred to as IR1, IR2, IR3, and IR4) are configured to perform positive withstand voltage tests (IR1), negative withstand voltage tests (IR2), leakage current measurements based on positive rated voltages (IR3), and leakage current measurements based on negative rated voltages (IR4), respectively. In each testing station, the voltage applied to the surface-mount capacitor C is set to be arbitrarily different, but the voltage and current measurements and determinations are performed in the same manner. For example, the set voltages are: IR1 applies a voltage approximately 3 to 5 times the rated voltage of the surface-mount capacitor C; IR2 applies the same voltage with the opposite polarity as IR1; IR3 applies the rated voltage with the same polarity as IR1; and IR4 applies a voltage with the same polarity as IR3 but opposite polarity.

[0056] like Figure 3 As shown in (a), during the movement of the conveying member 2, the measuring terminal 141 waits in a position separated from the conveying member 2 in a manner that does not contact the plate capacitor C.

[0057] exist Figure 3 In (b), the conveying member 2 stops at the position of the receiving hole 21, that is, the position of the chip capacitor C, which is the position between the measuring terminal 141 and the measuring terminal 142.

[0058] exist Figure 3 In step (c), after the conveying member 2 stops and a predetermined delay time has elapsed, the measuring terminal 141 is moved by a drive mechanism (not shown) (e.g., a motor, cylinder, solenoid coil, etc.) to contact the surface capacitor C. When the measuring terminal 141 contacts the surface capacitor C, it constitutes... Figure 4 The measuring circuit is inspected by the inspection device 3.

[0059] Figure 5This is a diagram showing the voltage and current waveforms of the surface capacitor C under measurement. The testing device 3 applies the voltage supplied from the power supply device 31 to the surface capacitor C via the testing terminals 141, 142 connected via the testing device 32.

[0060] First, describe the voltage and current waveforms when inspecting a normal, qualified chip capacitor C. For example... Figure 5 As shown, in the leakage current (insulation resistance) test of the chip capacitor C, a predetermined voltage is applied according to the performance of the chip capacitor C, and the current value is measured at a certain time (during the insulation resistance measurement period Tb) when the dielectric absorption (also known as polarization) and charging progress are certain. The insulation characteristics are evaluated based on the magnitude of this value.

[0061] The period during which voltage is applied to the surface-mount capacitor C includes a charging period Ta and an insulation resistance measurement period Tb after the charging period Ta. Furthermore, the charging period Ta includes a constant current charging period Ta1 and a constant voltage charging period Ta2. The current measuring unit 321 measures the current of the surface-mount capacitor C during the charging period Ta and the current during the insulation resistance measurement period Tb after the charging period Ta. Additionally, the voltage measuring unit 323 measures the voltage applied to the surface-mount capacitor C during the charging period Ta and the insulation resistance measurement period Tb.

[0062] During constant current charging (Ta1), the checking device 3 applies a voltage to the surface-mount capacitor C and charges it at a constant current value set by the current limiter of the power supply device 31 until a predetermined voltage is reached. The limiting current I2 of the power supply device 31 (the maximum current flowing through the surface-mount capacitor C) is set, for example, to 2mA~50mA. If the surface-mount capacitor C is normal, the voltage of Ta1 during constant current charging increases (rises) non-linearly and monotonically as shown by the solid line until the set voltage V1 is reached.

[0063] In addition, during constant current charging (Ta1), the limiting current I2 is set to be greater than the full scale of the measurement range. Figure 5 The measurable current value I1 is obtained. Therefore, during most of the constant current charging period Ta1, the actual current flowing through the plate capacitor C cannot be observed. Therefore, the current measuring unit 321 acquires a current value I1 that is less than the limiting current I2 as a measured value.

[0064] Furthermore, the current measuring unit 321 of this embodiment can set the measuring range to, for example, 10mA, 1mA, 100uA, 10uA, 1uA, 100nA, 10nA. Each measuring range (full-scale current value I1) and the limiting current I2 can be changed according to instructions from the control unit 324 or the control device 113.

[0065] During the constant voltage charging period Ta2, the voltage applied to the surface capacitor C remains constant after reaching the set voltage V1. During this time, the current flowing into the surface capacitor C decreases over time. The constant voltage charging period Ta2 is divided into two time regions: Ta21, where the constant voltage current range is exceeded, and Ta22, where the constant voltage current range is not exceeded.

[0066] The period Ta21, during which the constant voltage current range is exceeded, is the time period in which a current flowing through the surface capacitor C exceeds the measurement range that the current measuring unit 321 can measure. Therefore, this is the period during which the current measuring unit 321 cannot accurately measure the current change. Figure 5 In the example, the current flowing into the chip capacitor C is the limiting current I2, but it exceeds the measurement range. Therefore, the current measuring unit 321 obtains a current value I1 that is less than the limiting current I2 as the measured value.

[0067] The constant voltage current range non-exceeding period Ta22 is the time period during which the current flowing through the current measuring unit 321 in the plate capacitor C is within the measurement range that can be measured. Therefore, it is the period during which the current measuring unit 321 can accurately measure the current change.

[0068] When the specified charging period Ta has elapsed, the inspection device 3 (specifically, the current measuring unit 321) measures the leakage current of the plate capacitor C during the insulation resistance measurement period Tb.

[0069] During a series of charging and measuring cycles of Ta during charging and Tb during insulation resistance measurement, the measuring device 32 determines whether the chip capacitor C is qualified (whether it is a qualified product that meets a predefined threshold (good product) or a non-qualified product that does not meet a predefined threshold (defective product)).

[0070] The determination unit 325 acquires the values ​​of the current measured by the current measuring unit 321 or the voltage measured by the voltage measuring unit 323 during the charging period Ta and the insulation resistance measurement period Tb, and determines whether the chip capacitor C is qualified based on whether either the current or the voltage meets a predetermined threshold. Furthermore, the determination of the current or voltage includes the following process: the determination unit 325 acquires the differential value of the current measured by the current measuring unit 321 and the differential value of the voltage measured by the voltage measuring unit 323 from the differential waveform detection unit 322, and determines whether the chip capacitor C is qualified based on whether either of the differential values ​​meets a predetermined threshold.

[0071] More specifically, when the current detected by the current measuring unit 321 is outside the measurable range (the constant current range of constant current charging period Ta1 and constant voltage charging period Ta2 exceeds period Ta21), the determination unit 325 determines whether the chip capacitor C is qualified based on the voltage measured by the voltage measuring unit 323. For example, if the voltage is less than a threshold, the determination unit 325 determines that it is unqualified.

[0072] Furthermore, if the current detected by the current measuring unit 321 is outside the measurable range (the constant current range during constant current charging Ta1 and constant voltage charging Ta2 exceeds period Ta21), the determination unit 325 determines whether the chip capacitor C is qualified based on whether the change in voltage per unit time measured by the voltage measuring unit 323 (i.e., the differential value of the voltage detected by the differential waveform detection unit 322) meets a predetermined threshold. For example, if the differential value of the voltage is above (or exceeds) a predetermined value, the determination unit 325 determines that it is unqualified.

[0073] On the other hand, when the current measuring unit 321 is within the measurable range during the charging period Ta (the constant current range of Ta2 during constant voltage charging is not exceeded during period Ta22), the determination unit 325 determines whether the chip capacitor C is qualified based on whether the change in the current measured by the current measuring unit 321 or the voltage measured by the voltage measuring unit 323, or the change in the current measured by the current measuring unit 321 or the voltage measured by the voltage measuring unit 323 per unit time (i.e., the differential value of the current detected by the differential waveform detection unit 322) meets a predetermined threshold.

[0074] For example, if the current is greater than a threshold or the voltage is less than a threshold, the determination unit 325 determines that the current is unqualified. Alternatively, for example, if the differential value of the current or the differential value of the voltage is greater than or exceeds a specified value, the determination unit 325 determines that the current is unqualified. In other words, if the change in current and voltage is large, the determination unit 352 determines that the current is unqualified.

[0075] Therefore, during the charging period Ta, the determination unit 325 can detect the spike-like pulse wave of the current measured by the current measuring unit 321 or the voltage measured by the voltage measuring unit 323, and determine the plate capacitor C as unqualified.

[0076] For example, in Figure 5 In the upper voltage waveform, during the constant current charging period, when the range of constant current Ta1 and constant voltage current exceeds the range of period Ta21, the spike-shaped instantaneous voltage drop shown in waveform P1 cannot be accurately measured as a change in current by the current measuring unit 321, but can be detected as an abnormality in the chip capacitor C by monitoring the voltage.

[0077] Furthermore, the constant voltage current range, excluding the period Ta22, is the time period during which the current measuring unit 321 can measure the current flow, and the determination unit 325 is able to detect small changes in current. In cases where internal cracks or other abnormal insulation defects occur inside the chip capacitor C, the voltage may momentarily drop. Therefore, if the size of the voltage spike waveform exceeds a threshold, the product is determined to be defective, thereby eliminating chip capacitors C that may have a short lifespan.

[0078] As an example, waveform P2 is an abnormal current that can be detected by current measurement, but it does not show any obvious abnormality in the measurement results of the same timing voltage. When waveform P3, which shows a voltage drop of more than the specified value, is measured, waveform P4, which also shows a voltage drop of more than the specified value, is also observed in the current measurement results, thus it can be observed as an abnormal value in both voltage and current.

[0079] Subsequently, during the insulation resistance measurement period Tb, if the insulation resistance value calculated based on the voltage measured by the voltage measuring unit 323 and the current measured by the current measuring unit 321 is below a predetermined threshold, the judgment unit 325 determines that the chip capacitor C is unqualified. Thus, if both the peaked waveform and the magnitude of the leakage current (insulation resistance) are within the threshold (qualified), the chip capacitor C is determined to be qualified in the inspection at this testing station. On the other hand, if either the peaked waveform or the magnitude of the leakage current (insulation resistance) indicates an abnormal value, the chip capacitor C is determined to be unqualified in the inspection at this testing station. This improves the reliability of the inspection of the chip capacitor C.

[0080] Furthermore, as a condition for measuring voltage and current, for example, the threshold for the differential value of voltage is set to be approximately 20% to 50% of the applied voltage's + and - range. If the voltage exceeds this range, the determination unit 325 can determine it as unacceptable. Additionally, the determination threshold for the differential value of current is set based on the measurement range and the level of noise, and is set to a value larger than the noise level so that the noise does not affect the determination. For example, the determination threshold for the differential value of current can be set to a range of -10 nA / ms to +10 nA / ms as acceptable. If the current exceeds this range, the determination unit 325 can determine it as unacceptable.

[0081] exist Figure 3 In (d), when the inspection of the chip capacitor C is completed, the measuring terminal 141 is moved in a manner that separates it from the chip capacitor C by a drive mechanism not shown.

[0082] After that, Figure 3In step (e), the conveying member 2 moves, and the plate capacitor C moves to the next measuring station (or sorting and discharge section 15). Additionally, the next plate capacitor C to be inspected is moved to the positions of the measuring terminals 141 and 142 shown in the figure.

[0083] Furthermore, if both voltage and current are deemed unacceptable, voltage can be prioritized as the defective criterion. Alternatively, the priority of current can be increased through settings, or a configuration that can be arbitrarily determined by the user can be established.

[0084] In this embodiment, the inspection device 3 described above includes: a current measuring unit 321 that measures the current during the charging period Ta of the chip capacitor C and the current during the insulation resistance measurement period Tb after the charging period Ta; a voltage measuring unit 323 that measures the voltage applied to the chip capacitor C during the charging period Ta and the insulation resistance measurement period Tb; and a determination unit 325 that determines whether the chip capacitor C is qualified based on whether either the current measured by the current measuring unit 321 or the voltage measured by the voltage measuring unit 323 during the charging period Ta and the insulation resistance measurement period Tb meets a predetermined threshold.

[0085] Furthermore, a manufacturing method for a capacitor manufactured using the inspection method is described. This inspection method includes the following steps: measuring the current Ta during the charging period and the current Tb during the insulation resistance measurement period after the charging period using a current measuring circuit (current measuring unit 321); measuring the voltage applied to the capacitor C during the charging period Ta and the insulation resistance measurement period Tb using a voltage measuring circuit (voltage measuring unit 323); and determining whether the capacitor C is qualified based on whether either the current measured by the current measuring unit (current measuring unit 321) or the voltage measured by the voltage measuring unit (voltage measuring unit 323) during the charging period Ta and the insulation resistance measurement period Tb meets a predetermined threshold.

[0086] Furthermore, the following structure is described: The inspection program that the computer (inspection device 3) can execute enables the following processing: measuring the current Ta during the charging period of the chip capacitor C and the current Tb during the insulation resistance measurement period after the charging period Ta by the current measuring circuit (current measuring unit 321); measuring the voltage applied to the chip capacitor C during the charging period Ta and the insulation resistance measurement period Tb by the voltage measuring circuit (voltage measuring unit 323); and determining whether the chip capacitor C is qualified by the determination circuit (determination unit 325) based on whether either the current measured by the current measuring circuit and the voltage measured by the voltage measuring circuit during the charging period Ta and the insulation resistance measurement period Tb meets a predetermined threshold. The inspection program is stored in a storage medium. In addition, the inspection device 3 (computer) of this embodiment is a program product that can execute the above-described processes (functions) when the above-described inspection program is executed by the processor of the control device 113.

[0087] In this disclosure, sampling is performed while simultaneously monitoring voltage and current. When the current exceeds the measurable range (measuring range), the voltage change is used to detect non-conforming products. Once the current value enters the measurable range, the current is primarily used to detect non-conforming products. This process compensates for the shortcomings of each component, enabling more precise determination of conformity. By screening and excluding these as non-conforming products, the possibility of short-life products being mixed into the list of conforming chip capacitors can be reduced.

[0088] Until now, methods have been considered to determine defects based on whether the current value exceeds or does not exceed a predetermined value. In the inspection method disclosed herein, by setting the amount of change in current per unit time (differential value) as a threshold, a peak-shaped waveform can be set as a detection item for defect determination by means of a single parameter.

[0089] In this way, it is possible to eliminate the possibility of short lifespan in surface-mount capacitors that could not be detected in previous insulation resistance measurements.

[0090] This concludes the description of embodiments of the present disclosure, but the methods of the present disclosure are not limited to this embodiment. For example, in this embodiment, an inspection device 3 for inspecting and classifying multilayer ceramic capacitors, which are chip capacitors C, has been described. However, the electronic component screening device 1 may also be an apparatus for inspecting and classifying other chip capacitors, such as single-layer ceramic capacitors.

[0091] In addition, the inspection device 3 can be mounted on other devices such as a visual inspection device or a tape device to inspect the chip capacitor C.

[0092] Furthermore, for convenience, the determination unit 325 is described as an independent functional unit of the measuring device 32. However, as long as it has the functions described in this embodiment, the determination unit 325 can also be set as part of other structures (e.g., control unit 324, current measuring unit 321, differential waveform detection unit 322, voltage measuring unit 323, etc.), or it can be set in other devices other than the control device 113 or the measuring device 32.

[0093] Furthermore, this embodiment describes a conveying path with a straight, recessed shape on the upper surface of the feeder 122, and a structure for supplying the chip capacitor C to the conveying path within the emitter 123 via a distribution mechanism provided on the inlet side of the emitter 123, but it is not limited to this. For example, it could also be structured as follows: the feeder 122 is formed by multiple linear feeders capable of independent vibration conveying, and each linear feeder independently conveys the chip capacitor C and supplies it to the conveying path of the emitter 123.

[0094] In addition, in this embodiment, the measuring terminal 141, which is arranged facing the measuring terminal 142 on the base portion 111 side, is shown as an example of a probe terminal. However, the measuring terminal 141 may also be a sliding terminal that is always close to or in contact with the conveying member 2 in a state where it can be ejected in a direction separated from the conveying member 2 by the elastic member, or a roller terminal with a rotor provided at the front end of the terminal to reduce contact friction with the plate capacitor C, or other measuring terminals with other structures. In addition, the measuring terminal 141 may also perform the operation of contacting the plate capacitor C while the plate capacitor C is stopped in the measurable position, and separating from the plate capacitor C after measurement, as in the inspection portion 14 of this embodiment. It may also be a structure that is always close to or in contact with the conveying member 2 according to the terminal shape and does not actively move up and down relative to the plate capacitor C.

[0095] In addition, there is a period during charging where current measurement cannot be performed, so the invalidation period can be set by setting it.

[0096] Furthermore, the inspection program of this embodiment can be stored in the storage unit 326 or the storage unit of the control device 113 or other storage media, and can be executed by a computer such as the measuring device 32 or the control device 113.

[0097] in addition, Figure 3 The measuring terminals 141 and 142 are represented as receiving holes 21 (one of the eight receiving holes 21a to 21h) corresponding to a certain column in a certain measuring station, but the measuring terminals 141 and 142 can also be configured in the same way in all eight columns and in each measuring station.

[0098] In addition, in this embodiment, an example is shown where the determination unit 325 determines whether a condition is qualified based on current or voltage or their differential values. However, it is also possible that instead of two stages of qualification or non-qualification, multiple stages of thresholds are set to sort and determine multiple stages of three or more stages.

[0099] The structure of this disclosure is illustrated as follows. [1] An inspection device comprising: The current measuring unit measures the current during the charging period of the plate capacitor and the current during the insulation resistance measurement period after the charging period. A voltage measuring unit that measures the voltage applied to the plate capacitor during the charging period and the insulation resistance measurement period; and The determination unit determines whether the chip capacitor is qualified based on whether either the current measured by the current measuring unit or the voltage measured by the voltage measuring unit during the charging period and the insulation resistance measurement period meets a predetermined threshold. [2] According to the inspection device described in [1], wherein If the current detected by the current measuring unit is outside the measurable range, the determination unit determines whether the chip capacitor is qualified based on the voltage measured by the voltage measuring unit. [3] According to the inspection device described in [1] or [2], wherein During the charging process and when the current measuring unit is within its measurable range, the determination unit determines whether the chip capacitor is qualified based on whether the change in current per unit time measured by the current measuring unit meets a predetermined threshold. [4] According to the inspection device described in [1] or [2], wherein During the insulation resistance measurement, if the insulation resistance value calculated based on the voltage measured by the voltage measuring unit and the current measured by the current measuring unit is below a predetermined threshold, the determination unit will determine that the chip capacitor is unqualified. During the charging process, the determination unit detects spike-like pulse waves of the current measured by the current measuring unit or the voltage measured by the voltage measuring unit to determine that the chip capacitor is unqualified. [5] An inspection method comprising the following steps: The current during the charging period of the chip capacitor and the current during the insulation resistance measurement period after the charging period are measured by a current measuring circuit. The voltage applied to the chip capacitor during the charging period and the insulation resistance measurement period is measured by a voltage measuring circuit; and The determination circuit determines whether the chip capacitor is qualified based on whether either the current measured by the current measuring circuit or the voltage measured by the voltage measuring circuit during the charging period and the insulation resistance measurement period meets a predetermined threshold. [6] A method for manufacturing a capacitor includes the following steps: The current during the charging period of the chip capacitor and the current during the insulation resistance measurement period after the charging period are measured by a current measuring circuit. The voltage applied to the chip capacitor during the charging period and the insulation resistance measurement period is measured by a voltage measuring circuit; and The determination circuit determines whether the chip capacitor is qualified based on whether either the current measured by the current measuring circuit or the voltage measured by the voltage measuring circuit during the charging period and the insulation resistance measurement period meets a predetermined threshold. [7] An inspection procedure product includes an inspection procedure, wherein The inspection program, when executed by the computer's processor, includes the following functions: The current during the charging period of the chip capacitor and the current during the insulation resistance measurement period after the charging period are measured by a current measuring circuit. The voltage applied to the chip capacitor during the charging period and the insulation resistance measurement period is measured by a voltage measuring circuit; and The determination circuit determines whether the chip capacitor is qualified based on whether either the current measured by the current measuring circuit or the voltage measured by the voltage measuring circuit during the charging period and the insulation resistance measurement period meets a predetermined threshold.

[0107] Explanation of symbols 1: Electronic component screening device; 2: Conveying component; 3: Inspection device; 11: Main body of the device; 12: Supply unit; 13: Conveying unit; 14: Inspection unit; 15: Classification and discharge unit; 16: Recycling container; 21 (21a~21h): Receiving hole; 31: Power supply unit; 32: Measuring device; 111: Base unit; 112: Rotary drive unit; 113: Control unit; 121: Hopper unit; 122: Feeder; 123: Emitter; 124: Bucket; 141: Measuring terminal; 142: Measuring terminal; 151: Discharge path; 311: Rectifier circuit; 312: Filter circuit; 313: Constant voltage circuit; 314: Constant current circuit; 315: Output resistor; 321: Current measuring... 322: Differential waveform detection unit; 323: Voltage measurement unit; 324: Control unit; 325: Judgment unit; 326: Storage unit; 327: Communication unit; C: Chip capacitor; I1: Current value; I2: Limiting current; P: Rotating shaft; P1~P4: Waveform; R: Protection resistor; SW1: Interlocking relay; SW2: Voltage application relay; SW3: Polarity switching switch; T0: Input terminal; T1: First terminal; T2: Second terminal; Ta: Charging period; Ta1: Constant current charging period; Ta2: Constant voltage charging period; Ta21: Constant voltage current range exceeded period; Ta22: Constant voltage current range not exceeded period; Tb: Insulation resistance measurement period; V1: Set voltage.

Claims

1. An inspection device comprising: The current measuring unit measures the current during the charging period of the plate capacitor and the current during the insulation resistance measurement period after the charging period. A voltage measuring unit that measures the voltage applied to the plate capacitor during the charging period and the insulation resistance measurement period; and The determination unit determines whether the chip capacitor is qualified based on whether either the current measured by the current measuring unit or the voltage measured by the voltage measuring unit during the charging period and the insulation resistance measurement period meets a predetermined threshold.

2. The inspection device according to claim 1, wherein If the current detected by the current measuring unit is outside the measurable range, the determination unit determines whether the chip capacitor is qualified based on the voltage measured by the voltage measuring unit.

3. The inspection device according to claim 1 or 2, wherein During the charging process and when the current measuring unit is within its measurable range, the determination unit determines whether the chip capacitor is qualified based on whether the change in current per unit time measured by the current measuring unit meets a predetermined threshold.

4. The inspection device according to claim 1 or 2, wherein During the insulation resistance measurement, if the insulation resistance value calculated based on the voltage measured by the voltage measuring unit and the current measured by the current measuring unit is below a predetermined threshold, the determination unit will determine that the chip capacitor is unqualified. During the charging process, the determination unit detects spike-like pulse waves of the current measured by the current measuring unit or the voltage measured by the voltage measuring unit to determine that the chip capacitor is unqualified.

5. An inspection method comprising the following steps: The current during the charging period of the chip capacitor and the current during the insulation resistance measurement period after the charging period are measured by a current measuring circuit. The voltage applied to the chip capacitor during the charging period and the insulation resistance measurement period is measured by a voltage measuring circuit. as well as The determination circuit determines whether the chip capacitor is qualified based on whether either the current measured by the current measuring circuit or the voltage measured by the voltage measuring circuit during the charging period and the insulation resistance measurement period meets a predetermined threshold.

6. A method for manufacturing a capacitor, comprising the following steps: The current during the charging period of the chip capacitor and the current during the insulation resistance measurement period after the charging period are measured by a current measuring circuit. The voltage applied to the chip capacitor during the charging period and the insulation resistance measurement period is measured by a voltage measuring circuit. as well as The determination circuit determines whether the chip capacitor is qualified based on whether either the current measured by the current measuring circuit or the voltage measured by the voltage measuring circuit during the charging period and the insulation resistance measurement period meets a predetermined threshold.

7. An inspection procedure product, comprising an inspection procedure, wherein... The inspection program, when executed by the computer's processor, includes the following functions: The current during the charging period of the chip capacitor and the current during the insulation resistance measurement period after the charging period are measured by a current measuring circuit. The voltage applied to the chip capacitor during the charging period and the insulation resistance measurement period is measured by a voltage measuring circuit. as well as The determination circuit determines whether the chip capacitor is qualified based on whether either the current measured by the current measuring circuit or the voltage measured by the voltage measuring circuit during the charging period and the insulation resistance measurement period meets a predetermined threshold.

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