JPH09243695A - Method for measuring leakage current of capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable highly reliable measurement of leakage current by applying two kinds of voltage to a capacitor and continuously checking whether respective current values after predetermined time are in a predetermined range. SOLUTION: A capacitor 1 is connected in parallel with a long copper frame or the like, wherein while it is sequentially carried, measurement of leakage current of a number of capacitors is done by the number of probe terminals of a leakage current measuring device 5 at a time. The leakage current measuring device 5 is switched to two kinds of voltage by a controller 6. First, after a current value after predetermined time has elapsed with one kind of voltage, low voltage for example applied, voltage of the leakage current measuring device 5 is immediately switched by the controller 6 to high voltage, for measuring a current value after a predetermined time has elapsed. Thus once measurement is started, measurement is always done continuously without no intermission, and measured values of leakage current may not vary, thereby constantly enabling correct measurement.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for measuring a leakage current of a capacitor. More specifically, the present invention relates to a method for measuring a leak current of a capacitor, in which a measurement error caused by an abnormality in a manufacturing line is reduced when at least two types of voltages are applied and currents after a predetermined time are respectively inspected.

[0002]

2. Description of the Related Art Conventionally, for example, a capacitor such as a tantalum capacitor has a current limiting resistor R connected in series as shown in FIG. By measuring with ammeter A,
Inspection of the quality of the leak current is performed. Generally, in an equivalent circuit of a capacitor, as shown in FIG. 3B, a resistor R _ISO that causes a leak current and a resistor R ₀ and a capacitance C ₀ as a dielectric absorption current are connected in parallel with the capacitance C of the capacitor. The equivalent series resistance E
The SR and the inductance L are connected in series. In the case of a tantalum capacitor, the leak current inspection standard is that the current after a certain time when a voltage V ₁ lower than the rated voltage is applied and a voltage V _{2 that is} about twice as high as the rated voltage.
It is determined by whether or not the currents after a certain time when the voltage is applied are both within a certain value.

Such a leak current measuring method is performed, for example, as shown in the schematic view of FIG. 4, in which a plurality of capacitors 1 connected in parallel to a lead frame or the like are conveyed frame by frame, and are placed in front of each measuring instrument. Capacitor 1 sent
Are measured several times at a time, and the measured number is intermittently conveyed in the direction of arrow A.

In FIG. 4, the first leak current measuring device 2
According to (LC1 measurement), in the example shown in the figure, the probes 21 are connected to the four capacitors ₁ , a low voltage V ₁ is applied to the four capacitors at a time, and the capacitors are left for a time of, for example, about 20 to 32 seconds, Each subsequent current I ₁ is measured.
In the meantime, the measurement by the first leak current measuring device 2 (LC1 measurement) has already been completed, and the second leak current measuring device 3 (L
The probe 31 of the second leak current measuring device 3 is connected to the capacitor 1 that has been conveyed before (C2 measurement). Then, a high voltage V ₂ is applied to the four capacitors 1 at a time, the capacitors are left for a time of, for example, ₂₀ to 32 seconds, which is the same time, and the current I ₂ of each capacitor thereafter is measured. After both the measurements by the first and second leak current measuring devices 2, 3 are completed, the connected capacitors 1 are transported by the measured number.

FIG. 5 shows the relationship between the voltage applied by the first and second leak current measurements and the current at that time.
(A). In FIG. 5A, the time t ₁ is the time measured by the first leak current measuring device 2, the voltage V ₁ is applied, and the charging current that flows first at the beginning decreases exponentially. The current I ₁ at the elapse of t ₁ is measured as the first leak current value. The time t ₀ is the time during which the first leak current measuring device 2 finishes the measurement and reaches the second leak current measuring device 3, during which time the residual voltage of the _first leak current measuring voltage V ₁ remains. V ₀ is applied to the capacitor. The next time t ₂ is the measurement time by the second leak current measuring device 3, and the voltage V ₂ is applied. Also at this time, a large amount of charging current flows at the beginning of voltage application, exponentially decreases, and the current value I ₂ at the elapse of time t ₂ is measured as the second leakage current value. When the voltage is set to 0 after the lapse of time t ₂ , a reverse current D instantaneously flows.

After the measurement of the second leakage current is completed, the discharger 4
The capacitor 1 conveyed before is discharged by connecting a resistor between both electrodes of the capacitor 1. This series of operations is performed intermittently, for example, every four pieces. Also, the capacitor 1 which has been discharged is further transported to the next step,
According to the measurement result of the leakage current, the defective product is cut and removed, and the non-defective product is directly sent to the next step.

[0007]

In the conventional method of measuring the leakage current at one of the stations while transporting each station in the process of manufacturing the capacitor by connecting the capacitors, the manual operation is performed somewhere on the manufacturing line. When the frame is stopped due to the stop or the alarm abnormal stop, the second leak current measuring device 3 has a problem that the leak current value becomes a small value at the time of abnormality.

The present inventor diligently investigated the cause of the measured value of the leakage current by the second leakage current measuring device being low when the frame conveyance is interrupted. Found. That is, the conventional leak current measurement includes the first leak current measurement and the second leak current measurement as described above.
Leakage current measurement is done at a different station and at a different station. Therefore, the capacitor 1 being transferred is present between the first and second leak current measuring devices 2 and 3, and the residual voltage V ₀ is applied during the time t ₀ . If there is no trouble in the production line and the products are always transported in a fixed number, the time between the first leak current measurement and the second leak current measurement is constant, and there is no problem if the measurement conditions are the same. , a failure such as a trouble of the production line e.g. defective cutting occurs that time t _f (see FIG. 5 (b)) is abnormally long. When the time until the measurement of the second leak current becomes long, the dielectric absorption of the capacitor progresses a lot due to the residual voltage V ₀ , and as shown in FIG. 5B,
The measured value of the second leak current becomes low (the broken line shows the change in current when normal). As a result, the measured value of the first leak current may be far from the measured value, and the accuracy (reliability) of the measuring device is reduced.

On the other hand, it may be possible to eliminate the residual voltage of the measurement voltage V ₁ by discharging after the measurement of the first leak current, but it is impossible to completely discharge the discharge for several tens of seconds, and Returning the capacitor to which the voltage has been applied to the state before the voltage application requires a long discharge time and is not practical.

The present invention has been made to solve such a problem and has a highly reliable leakage current of a capacitor which does not affect the measurement of the leakage current of the capacitor even when the manufacturing line is stopped due to some abnormality. It is intended to provide a measuring method of.

[0011]

According to the method for measuring the leakage current of a capacitor according to the present invention, two kinds of voltages are applied to the capacitor and it is checked whether or not the current value after a predetermined time is within a predetermined range. The method for measuring the leakage current of a capacitor is characterized in that the measurement using the two types of voltages is continuously performed.

A plurality of capacitor pellets are connected in parallel to a long frame, the frames are conveyed so as to pass through a station of each manufacturing process of capacitors, and the leak current is measured at one of the stations. In this case, the effect of the present invention is particularly exhibited.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Next, a method for measuring a leakage current of a capacitor according to the present invention will be described with reference to the drawings.

FIG. 1A is a schematic diagram for explaining the leak current measuring method of the present invention, and FIGS. 1B and 1C are flow charts thereof. The capacitor 1 is connected to a long copper frame or the like in parallel as in the conventional case, and while being sequentially transported, the number of probe terminals of the leak current measuring device 5 (three in FIG. 1, different from FIG. 4 but limited in number). Not connected), and the leak current of that number of capacitors is measured at one time. In the present invention, the leak current measuring device 5 is switched to two types of measurement voltage by the controller 6, and first, one voltage, for example, a low voltage V ₁
Immediately after measuring the current value after a lapse of a predetermined time, the controller 6 immediately switches the voltage of the leak current measuring device 5 to a high voltage V ₂ and measures the current value after a lapse of the predetermined time. Is characterized by.

That is, according to the present invention, since two kinds of voltages are always measured continuously after the measurement of the leak current is started, the first leak current is measured and then left for a long time and then the second leak current is measured. It does not happen that a leak current measurement of is performed. Even if a line break occurs somewhere in the manufacturing line, the leak current is measured until it is completed, and then the break occurs. This is because the transfer of the connected capacitors is originally stopped during the leak current measurement time, and the capacitors are intermittently transferred each time the work of each process such as measurement of the leak current is completed.

After the measurement of these two kinds of leak currents is completed, the capacitors 1 connected to each other are conveyed to the next process by the number thereof and sent to the discharger 4.
Is connected to the discharger 4 and discharged. After that, the defective product is sent to the defective ejector 7, and only the defective product is cut off from the connecting portion according to the instruction from the controller 6 based on the measurement result of the current measuring device 5 in the previous process and put in the defective product box (NG). It is sent to the next process while being connected (G
O). The flow chart of this series of steps is shown in FIG.
(B).

In the above-mentioned method, after measuring the leak current, a series of capacitors are conveyed by the number of measured capacitors and discharged by the dischargers 4 provided in different stations. By doing so, leakage current measurement and discharge can be performed in parallel at the same time, which is convenient for improving the rotation speed of the equipment. However, if the voltage of the leak current measuring device 5 can be switched to 0V,
The voltage applied to the capacitor 1 may be switched to 0 V and discharged at the same station after the two types of current measurements are completed. FIG. 1C is a flowchart showing the steps at this time. In this way, it is not necessary to provide a separate discharge device. The rotation of the production line, as described later,
By increasing the number of probe terminals of the current measuring device or providing a plurality of leak current measuring devices, it is possible to increase the number of measurements at one time, which leads to faster processing.

FIG. 2 shows the relationship between the applied voltage and the current when the leak current is measured by continuously applying two kinds of voltages by the method of the present invention. In FIG. 2, first, V
_When the voltage of ₁ is applied to the capacitor, the charging current flows,
The current value I decreases exponentially. For example between the voltage V ₁ of the 20 seconds to time t ₁ is applied to measure the current value I ₁ of the elapse of time t _1. Immediately thereafter, the voltage applied to the capacitor is switched to V ₂ , and the capacitor is left for a time t ₂ of, for example, 32 seconds. When this voltage becomes high, the charging current rapidly increases again, and then the current decreases exponentially. The controller 6 (see FIG. 1) measures the current I ₂ at the time when the time t ₂ has passed, and judges whether both the currents I ₁ and I ₂ are within the specified values.
By. In FIG. 2, D indicates a current flowing in the opposite direction at the moment when the voltage is set to zero.

According to the present invention, since two kinds of leak currents are continuously measured by one measuring instrument, it takes a lot of time for the step of current measurement, and it is not balanced with the time required for other discharges. In this case, the operating rate of the equipment will decrease. However, in such a case, the number of probe terminals of the leak current measuring device may be increased or two or more leak current measuring devices may be arranged to carry out the transportation of the capacitor for each number to be measured at one time. On the contrary, when the first and second current measurement times are different, the throughput is improved by performing continuous measurement on each of the two devices.

[0020]

According to the present invention, since two types of current measurements are continuously measured and there is no intermittent time between them, even if the capacitor transfer line is stopped due to a failure of any process, The time between different types of measurements does not vary. As a result, even when a line failure or the like interrupts the transfer of the capacitor, there is no cause of variation in the leak current measurement value, there is no need for re-inspection, and accurate measurement is always possible, A highly reliable inspection can be performed.

[Brief description of drawings]

FIG. 1 is a schematic view and a flowchart for explaining a leak current measuring method of the present invention.

FIG. 2 is a relationship diagram between an applied voltage and a current when measuring a leak current according to the method of the present invention.

FIG. 3 is an equivalent circuit diagram for measuring a leak current of a capacitor.

FIG. 4 is a diagram illustrating a conventional method for measuring a leak current of a capacitor.

FIG. 5 is a relationship diagram between an applied voltage and a current when measuring a leak current by a conventional method.

[Explanation of symbols]

 1 Capacitor 4 Discharger 5 Leakage current measuring instrument

Claims (2)

[Claims] 1. A method for measuring a leak current of a capacitor, which comprises applying two types of voltage to a capacitor and inspecting whether or not a current value after a fixed time falls within a predetermined range. A method for measuring the leakage current of a capacitor, which is characterized by continuously measuring by voltage. 2. A plurality of capacitor pellets are connected in parallel to a long frame, the frames are conveyed so as to pass through a station of each capacitor manufacturing process, and the leak current is measured at one of the stations. The method for measuring leak current according to claim 1, wherein