JP5206493B2 - Ceramic capacitor sorting method and sorting apparatus - Google Patents

Description

  The present invention relates to a ceramic capacitor sorting method and sorting apparatus for surge resistance.

  Conventionally, surge absorbing parts such as varistors and surge absorbers have been used to prevent dielectric breakdown of multilayer ceramic capacitors due to surge current. However, in recent years, as electronic devices become lighter, thinner and smaller, it is strongly demanded to reduce the mounting area on the mounting substrate. For this reason, it has been proposed to omit surge absorbing parts by adding a surge resistance function to the multilayer ceramic capacitor itself. For example, Patent Document 1 discloses a multilayer ceramic capacitor with a discharge gap. In this multilayer ceramic capacitor, the distance between a pair of discharge electrodes formed on the upper surface of the capacitor body is short. As a result, when a surge flows in, a discharge is generated between the discharge electrodes, preventing the surge from flowing into the capacitor and preventing the capacitor from being destroyed.

  By the way, the multilayer ceramic capacitor described in Patent Document 1 is provided with a discharge electrode in order to surely generate a surge discharge outside the capacitor, but in short, the surge discharge between the external electrodes starts from the breakdown voltage of the capacitor. If the voltage is low, surge discharge occurs outside the capacitor (that is, between the external electrodes) without providing a discharge electrode. In this case, it is necessary to select a capacitor that reliably generates a surge discharge outside the capacitor and a capacitor that does not. However, the conventional sorting apparatus cannot perform the sorting. For example, in the sorting apparatus described in Patent Document 2, a pulse voltage higher than the rated voltage value of the capacitor is supplied to the capacitor, the pulse voltage value applied to the capacitor at that time is monitored, and the monitored pulse voltage value It is said that the abnormality inside the capacitor can be detected based on the above.

JP-A-6-251981 JP-A-7-320993

  However, the cause of the abnormality of the pulse voltage value monitored by the sorting device of Patent Document 2 is that it is caused by surge discharge between external electrodes (surge discharge that occurs outside the capacitor) or by short-circuit due to internal breakdown. There are two cases, and there is a problem that the insulation resistance must be measured again every time in order to identify the true cause.

  SUMMARY OF THE INVENTION Therefore, a main object of the present invention is to provide a ceramic capacitor selection method and a selection apparatus capable of selecting a capacitor in which a surge discharge is reliably generated between external electrodes without performing an insulation resistance measurement. .

  The present invention provides a ceramic body, a first external electrode and a second external electrode provided on the outer surface of the ceramic body, and a first external electrode provided inside the ceramic body and joined to the first external electrode. A ceramic capacitor having a first internal electrode and a second internal electrode joined to the second external electrode, wherein the rated voltage value of the ceramic capacitor is between the first external electrode and the second external electrode. The surface discharge current value generated when a substantially pulsed DC high voltage is applied at the surface leakage current detection terminal that is applied to the surface center of the ceramic body by applying a larger substantially pulsed DC high voltage. A method of selecting a ceramic capacitor, characterized in that the ceramic capacitor is selected by detecting and judging whether the ceramic capacitor has a surge resistance performance based on a creeping discharge current value. That.

  In this invention, the surface leakage current detection terminal generated when a substantially pulsed DC high voltage is applied is detected at the surface leakage current detection terminal brought into contact with the center of the surface of the ceramic element body. Whether the surge performance is good or not can be judged easily and reliably. That is, a capacitor in which surge discharge is reliably generated outside the capacitor by applying a pulsed DC high voltage larger than the rated voltage value of this capacitor according to the capacitor rating (a capacitor that is good in surge resistance performance) In this case, the creeping discharge current value detected at the surface leakage current detection terminal is equal to or greater than a predetermined current threshold. On the other hand, in the case of a capacitor that does not generate surge discharge outside the capacitor (a capacitor that is defective in terms of surge resistance), the creeping discharge current value detected at the surface leakage current detection terminal is less than the predetermined current threshold value. It becomes. Therefore, whether or not the surge resistance performance of the ceramic capacitor is good can be easily and reliably determined based on whether or not the creeping discharge current value detected at the surface leakage current detection terminal has reached a predetermined current threshold value.

  The present invention also provides a pulse supply circuit for applying a substantially pulsed DC high voltage between a pair of external electrodes of a ceramic capacitor, and a substantially pulsed DC high voltage in contact with the center of the surface of the ceramic body of the ceramic capacitor. A surface leakage current detection terminal for detecting a creeping discharge current generated when a voltage is applied, a creeping discharge current value measuring circuit for measuring a current value of the creeping discharge current detected at the surface leakage current detection terminal, and a creeping discharge current value A determination circuit that determines whether or not the creeping discharge current value measured by the measurement circuit has reached a predetermined current threshold; and a control unit that instructs the selection operation of the ceramic capacitor based on the determination result of the determination circuit. This is a ceramic capacitor sorting apparatus.

  According to the present invention, it is possible to easily and reliably determine whether the ceramic capacitor has surge resistance performance with a screening device having a simple circuit configuration.

  According to the present invention, a ceramic capacitor is detected by detecting a creeping discharge current value generated when a substantially pulsed DC high voltage is applied at a surface leakage current detection terminal brought into contact with the center of the surface of the ceramic body. It is possible to easily and reliably determine whether the surge resistance is good or bad. As a result, it is possible to select a capacitor in which surge discharge is reliably generated between the external electrodes without measuring the insulation resistance.

  The above-mentioned object, other objects, features and advantages of the present invention will become more apparent from the following description of embodiments for carrying out the invention with reference to the drawings.

It is an electric block diagram for demonstrating one Embodiment of the sorting apparatus of the ceramic capacitor | condenser which concerns on this invention. FIG. 2 is a waveform diagram of a substantially pulsed DC high voltage supplied from the sorting apparatus shown in FIG. 1. It is a schematic diagram for demonstrating the selection method of the ceramic capacitor which concerns on this invention.

  FIG. 1 is an electric block diagram for explaining a sorting apparatus 1 for multilayer ceramic capacitors. The sorting device 1 generally includes a pulse supply circuit 2, a surface leakage current detection terminal 22, a creeping discharge current value measurement circuit 24, and a determination circuit 26. Furthermore, the sorting device 1 also includes an electrical property sorting circuit 30 that measures the capacitance, dielectric loss tangent, and insulation resistance of the capacitor. In FIG. 1, the symbol C is a capacitance component of the ceramic capacitor 40 to be sorted, and the symbol Rc is a resistance component of the external electrode 44 of the ceramic capacitor 40 to be sorted, the surface of the ceramic body 42, and the external electrode 46 (described later). It is.

  The pulse supply circuit 2 applies a pulsed DC high voltage between the pair of external electrodes 44 and 46 of the ceramic capacitor 40 to be sorted. The pulse supply circuit 2 includes a CPU (control device) 4 that controls the DC high-voltage power supply 10 and applies a pulsed DC high voltage to the capacitor 40 under specified pulse application conditions. A D / A converter 6 that converts a control signal from the CPU 4 from digital to analog and an amplifier (AMP) 8 that amplifies the converted control signal are electrically connected between the CPU 4 and the DC high-voltage power supply 10. Has been. Furthermore, between the output terminal of the DC high-voltage power supply 10 and the high voltage application terminals 21a, 21b, a T-shape configured by a charging resistor 14, an energy storage capacitor 16, and a discharging resistor 18 via a charging switch 12. The circuit and the discharge switch 20 are electrically connected.

  The pulse supply circuit 2 applies a DC high voltage to the energy storage capacitor 16 to charge the energy storage capacitor 16 when the charging switch 12 is in the ON state and the discharge switch 20 is in the OFF state. When the energy storage capacitor 16 is sufficiently charged, the charging switch 12 is turned off and the discharging switch 20 is turned on, and a pulsed DC high voltage having a pulse waveform as shown in FIG. generate.

  On the other hand, the surface leakage current detection terminal 22 is a creeping discharge current value measurement circuit 24 that measures the current value of the creeping discharge current detected by the surface leakage current detection terminal 22, and the creeping discharge current that is measured by the creeping discharge current value measurement circuit 24. The pulse supply circuit 2 passes through a determination circuit 26 that determines whether or not the value has reached a predetermined current threshold value, and a D / A converter 28 that converts a control signal from the determination circuit 26 from digital to analog. The CPU 4 is electrically connected. In addition to the control function of the DC high-voltage power supply 10, the CPU 4 also has a function of instructing the sorting operation of the capacitor 40 based on the determination result of the determination circuit 26.

  The predetermined current threshold set in advance in the determination circuit 26 uses an “appropriate current threshold” obtained by a method described in an embodiment described later. At this time, when the surface leakage current detection terminal 22 is brought into contact with the center of the upper surface of the ceramic body 42, the distance between the external electrodes 44 and 46 and the leakage current detection terminal 22 is compared with the distance between the external electrodes 44 and 46. The surge start voltage is lowered because the distance is reduced. Therefore, separately, the pulse application test and the subsequent insulation resistance measurement are carried out without using the surface leakage current detection terminal 22, and the current threshold is set so as to be the same as the result obtained there.

  Next, a method for sorting the capacitors 40 using the sorting apparatus 1 will be described. As shown in FIG. 3, after the capacitor to be sorted 40 is set in the sorting apparatus 1, the high voltage application terminals 21a and 21b are brought into contact with the pair of external electrodes 44 and 46 of the capacitor to be sorted 40, respectively. Further, the surface leakage current detection terminal 22 is brought into contact with the center of the upper surface of the ceramic body 42 of the capacitor to be sorted 40 (the center between the pair of external electrodes 44 and 46). The front end portion of the surface leakage current detection terminal 22 has a needle shape. The pulsed DC high voltage generated in the pulse supply circuit 2 is applied to the pair of external electrodes 44 and 46 of the capacitor 40 to be sorted through the high voltage application terminals 21a and 21b. The pulsed DC high voltage is larger than the rated voltage value of the capacitor 40, and the application time is 10 ns or less.

  When a pulsed DC high voltage is applied to the capacitor 40, the surface discharge current detection terminal 22 detects a creeping discharge current generated on the surface of the ceramic body 42 of the capacitor 40. The determination circuit 26 determines whether or not the detected creeping discharge current has reached a predetermined current threshold value. The determination result is transmitted to the CPU 4 of the pulse supply circuit 2 via the D / A converter 28. The CPU 4 determines that the capacitor 40 that has not reached the predetermined current threshold is a defective product (capacitor in which creeping discharge has not occurred) in surge resistance, and transmits it to eliminate it. On the other hand, the capacitor 40 that has reached the predetermined current threshold is determined as a non-defective product (capacitor in which creeping discharge has occurred) in surge resistance.

  The capacitor 40 determined to be a non-defective product in surge resistance performance is further measured by measuring the capacitance, dielectric loss tangent and insulation resistance in the electrical characteristic selection circuit 30. If a broken capacitor 40 occurs, it can be eliminated.

  According to the above selection method, the surface leakage current detection terminal 22 brought into contact with the center of the upper surface of the ceramic body 42 detects the creeping discharge current value generated when a pulsed DC high voltage is applied. In the case of a capacitor 40 that reliably generates surge discharge outside the capacitor (a capacitor that is non-defective in terms of surge resistance), the creeping discharge current value detected by the surface leakage current detection terminal 22 is a predetermined current threshold value. That's it. On the other hand, in the case of a capacitor 40 that does not generate surge discharge outside the capacitor (a capacitor that is defective in surge resistance), the creeping discharge current value detected by the surface leakage current detection terminal 22 is a predetermined current. Below the threshold. Therefore, the quality of the surge resistance performance of the ceramic capacitor 40 can be easily and reliably determined based on whether or not the creeping discharge current value detected at the surface leakage current detection terminal 22 has reached a predetermined current threshold value. . As a result, a capacitor (a capacitor that is good in terms of surge resistance) 40 that reliably generates a surge discharge between the external electrodes 44 and 46 is selected without measuring the insulation resistance that is required in the conventional sorting method. Therefore, it is possible to select all the items for the anti-surge performance.

  Further, by monitoring the surface leakage current value, factors (such as the surface state of the ceramic body 42) other than the design structure that give the surge resistance can be clarified. Furthermore, by introducing the sorting by the sorting device 1 into the manufacturing process, it is possible to quickly and sensitively detect changes in factors other than the design structure that give the surge resistance and surge resistance performance.

  In addition, this invention is not limited to the said embodiment, In the range of the summary, it changes variously.

  The screening device 1 shown in FIG. 1 was used to select whether the multilayer ceramic capacitor had good surge resistance. In order to verify the usefulness of the anti-surge performance selection, electrical characteristics selection (capacitor capacitance and insulation resistance) is performed in advance to cover the capacitors that are removing defective products such as inherently short-circuit defects. Selected for selection. The insulation resistance measuring device at this time uses a 4349B 4-channel high resistance meter manufactured by Agilent, and the insulation resistance selection condition is that a voltage of 100 Vrms is applied for 5 seconds, and an insulation resistance of less than 6.5 MΩ is regarded as a defective product. The selection criteria to be adopted were adopted. In addition, the capacitance measuring apparatus uses 4268A CAPACITANT METER manufactured by Agilent, and the capacitance selection condition is that the applied voltage is 1 kVrms and the measurement frequency is 1 kHz, and the capacitance is less than 5.5 pF. We adopted a selection standard that makes things defective.

A capacitor having a rated voltage of 100 V and a size of 2.0 mm × 1.25 mm × 0.85 mm is used, and all capacitors are of the same lot. The pulsed DC high voltage of the pulse supply circuit 2 was set to 15 kV. The number of samples was 10,000. The current threshold value preset in the determination circuit 26 is set to three types of patterns. That is, pattern (1) was set to threshold values of less than 5.00 A (defective product I), 5.00 A or more and less than 20.00 A (defective product II), and 20.00 A or more (good product). For pattern (2), threshold values of less than 5.00 A (defective product I), 5.00 A or more and less than 40.00 A (defective product II), and 40.00 A or more (good product) were set. For pattern (3), threshold values of less than 5.00 A (defective product I), 5.00 A or more and less than 60.00 A (defective product II), and 60.00 A or more (good product) were set.

  Table 1 shows the results of sorting with these three types of patterns. As for the number of defective capacitors I generated, the threshold values of the three types of patterns are the same, so there is almost no difference between the patterns. However, the number of defective capacitors II was found to be different between the three patterns.

  Table 2 is a graph showing the number of shorts in defective products and the number of shorts in non-defective products for each of the three types of patterns. Since electrical characteristics selection (capacitance and insulation resistance of the capacitor) is performed in advance to remove defective products such as inherently short-circuit defects, these short-circuited capacitors are connected to the pulse supply circuit 2 pulse. It is generated by applying a high DC voltage. Whether or not the capacitor after the selection of whether or not the surge resistance is good was short-circuited was confirmed by performing the electric characteristic selection again under the same conditions.

All capacitors of the defective product I were short-circuited. These defective I capacitors were considered to have short-circuited because creeping discharge did not occur or was extremely difficult to occur. In the case of pattern (1), the number of shorts of the defective product II capacitor was the lowest, but the occurrence rate of the short circuit of the non-defective product was high. This is probably because the set current threshold value of the determination circuit 26 was too low, so that a sufficient value of the creeping surface current did not flow, but the product was determined to be non-defective. On the other hand, in the case of the pattern (3), the number of shorts of the capacitor of the defective product II was the highest, but the short-circuit occurrence rate of the capacitor of the defective product II was almost the same as that of the pattern (2). This is probably because the set current threshold of the determination circuit 26 was too high, and the creeping surface current of a sufficient value flowed, but the product was determined to be defective II. In the case of pattern (2), all the defective product capacitors were short-circuited, and the occurrence rate of the non-defective product capacitors was zero. This proves that the setting of the pattern (2) is appropriate, and if this “appropriate current threshold” is used, it is possible to determine whether the surge resistance is good or bad.

1 Sorting Device 2 Pulse Supply Circuit 4 CPU (Control Device)
22 Surface Leakage Current Detection Terminal 24 Creeping Discharge Current Value Measurement Circuit 26 Judgment Circuit

Claims (2)

A ceramic body, a first external electrode and a second external electrode provided on an outer surface of the ceramic body, and a first body provided in the ceramic body and joined to the first external electrode A method of selecting a ceramic capacitor having an internal electrode and a second internal electrode joined to the second external electrode,
A surface leak in which a substantially pulsed DC high voltage larger than the rated voltage value of the ceramic capacitor is applied between the first external electrode and the second external electrode to bring it into contact with the center of the surface of the ceramic body. At the current detection terminal, the creeping discharge current value generated when the substantially pulsed DC high voltage is applied is detected, and the surge resistance performance of the ceramic capacitor is judged based on the creeping discharge current value, A method for sorting ceramic capacitors, comprising sorting ceramic capacitors. A pulse supply circuit for applying a substantially pulsed DC high voltage between a pair of external electrodes of a ceramic capacitor;
A surface leakage current detection terminal for detecting a creeping discharge current generated when the substantially pulsed DC high voltage is applied in contact with the center of the surface of the ceramic body of the ceramic capacitor;
A creeping discharge current value measuring circuit for measuring a current value of the creeping discharge current detected at the surface leakage current detection terminal;
A determination circuit for determining whether or not the creeping discharge current value measured by the creeping discharge current value measuring circuit has reached a predetermined current threshold;
A control unit for instructing the selection operation of the ceramic capacitor based on the determination result of the determination circuit;
An apparatus for sorting ceramic capacitors, comprising:

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