JP2008305891A - Inspection apparatus for capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inspection apparatus for deciding correctness of an electrolytic capacitor in semi-shorted state, at a high speed, prior to reflowing. <P>SOLUTION: The inspection apparatus comprises a constant current power source part 5, having a selecting switch 4 for outputting different constant currents, connecting terminals 7 and 8 for applying the current of the constant current power source part 5 to a capacitor, a short switch 9, consisting of a switching element for shorting/opening the connection terminals 7 and 8, a voltage circuit 10 for measuring the voltage of the connecting terminal 7, and a control part 19 such as a sequencer 16 for controlling the same. A capacitor 6 which is to be measured is connected to the connecting terminals 7 and 8, and the switch 4 is selected according to a capacitance of the capacitor. A current I is made to flow, from the constant current power source part 5 so that the capacitor is charged, and shorting is determined, based on the rise of voltage or the voltage rise time. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an inspection apparatus used for short inspection and capacity inspection of electrolytic capacitors used in various electronic devices.

  FIG. 8 is a circuit diagram showing a part of a conventional electrolytic capacitor resistance test discriminating apparatus, in which a resistor 31 and an electrolytic capacitor 32 to be measured are connected in series, and these voltage dividing resistors are set at a set voltage 34 by a comparator 33. In contrast, it was determined to be a non-defective product when it was higher and a defective product when it was lower.

  Further, as a possibility of being used as a short circuit detection of a conventional electrolytic capacitor, Patent Document 1 discloses that a terminal is left in a short state in a high temperature atmosphere before the inspection of the electrolytic capacitor, and a characteristic inspection is performed thereafter. A method is described.

Electrolytic capacitors that have become good products by these inspection methods can be charged normally even if they are charged, and are treated as good products.
JP-A-11-111580

  In recent years, lead-free has been promoted with the reduction of environmentally hazardous substances. Even in the soldering of electronic equipment, lead-free is becoming the main component, and the temperature of the reflow furnace must be set high to improve solderability. For this reason, in electrolytic capacitors used in electronic equipment, the internal pressure rises due to the temperature at the time of soldering and stress is applied to the capacitor elements. The number of semi-short-circuits where the resistance between them is low is increasing.

  With respect to this half short-circuited electrolytic capacitor, when the current is set free and the voltage is gradually increased, the relationship between the voltage and the current is graphed. As shown in FIG. 35 is generated, and when the applied voltage is increased, the current value is suppressed to a low level, and the current peak 35 is approximately in the range 36 of 40 to 120 mA. This current peak 35 is half of the electrolytic capacitor. It can be presumed that the device was in a short state.

  In the resistance test discriminating apparatus as shown in FIG. 8, for example, to saturate a 2500 μF electrolytic capacitor, 4τ = 4 × 0.0025 × 20 = 0.2 (seconds), a resistance of 20Ω at a voltage of 1V When 31 is used, a maximum current of 50 mA flows as shown in FIG. This value is 40 mA or more at which the half-short state is restored, so that what was in the half-short state flows to the next process as a non-defective product, and there is a high possibility that a half-short state will occur at the time of reflow. Yes.

  When it is desired to discriminate the 1 kΩ resistor 31, the saturation voltage divided by 1V is about 0.98V as shown in FIG. 10B, but the 500Ω discrimination voltage is 0.96V, and the 2kΩ discrimination voltage is 0. Since it is very close to .99V, the detection accuracy of the short resistance becomes extremely poor.

  Therefore, when the charging resistance is increased to 100Ω to increase accuracy, the discrimination voltage of 500Ω, 1kΩ, and 2kΩ is 0.83V, 0.91V, and 9.5V, and the difference between the discrimination voltages is widened and the accuracy is improved. However, since the voltage saturation time of the electrolytic capacitor is four times as long as 0.4 sec, it takes a lot of inspection time, so that it is difficult to go online.

  Moreover, in patent document 1, although a half-short state becomes easy to reproduce, there exists a subject that possibility that the half-short of some electrolytic capacitors will be reset becomes high.

  The present invention solves such a conventional problem and provides an inspection apparatus capable of performing a short inspection or a capacity inspection at high speed before reflowing an electrolytic capacitor in a semi-shorted state to determine whether it is acceptable or not. It is the purpose.

  In order to achieve the above object, the present invention provides a capacitor inspection device for inspecting whether a capacitor is short-circuited or not by passing a current through the capacitor, wherein the inspection device outputs a different constant current. A constant current power supply unit having a connection terminal for energizing a capacitor for measuring the current of the constant current power supply unit, a shorting switch comprising a switching element for short-circuiting or opening the connection terminal, and a voltage of the connection terminal It consists of a configuration including a voltage circuit to measure and a control unit such as a sequencer for controlling them, and a capacitor to be measured is connected to the connection terminal, a switch is selected according to the capacitor capacity, and the current I from the constant current power supply unit To charge the capacitor, and perform a pass / fail judgment or capacity check based on the voltage rise or voltage rise time. It is an inspection apparatus of the capacitor, wherein the door.

  In addition, a capacitor to be measured is connected to the connection terminal, a switch is selected according to the capacitance of the capacitor, the current I is supplied from the constant current power supply unit, and the capacitor is charged. After time T, a current II smaller than the current I is supplied. The capacitor is inspected by performing a pass / fail judgment or a capacity inspection based on voltage fluctuation after the T time.

  As described above, according to the present invention, the switch is selected from the constant current power supply unit according to the capacitance of the capacitor and charged by flowing the current I at a level that can maintain the half-short state, and the voltage rises or the voltage rise time By performing a short pass / fail determination or a capacity inspection, it is possible to easily determine pass / fail.

  In addition, by charging the current II smaller than the current I after the T time and further charging, if the product is non-defective after the T time, the voltage rises according to the current II. Even if II is passed, the voltage does not increase, and pass / fail judgment can be easily performed.

  In addition, by rapidly charging the electrolytic capacitor with a constant current I at a level that can maintain a half-short state, and measuring the half-short state with a minute current II, even if the judgment resistance R is increased, I2 is reduced. Since the determination voltage V2 (= I2R) can be reduced, the charging voltage V2 + α is reduced, the charging time can be shortened, and the speed can be increased.

(Embodiment 1)
Hereinafter, the first embodiment of the present invention, in particular, the invention described in claims 1 and 2 will be described in detail.

  FIG. 1 is a circuit configuration diagram of a capacitor inspection apparatus according to Embodiment 1 of the present invention. 2 is a timing chart of FIG. 1, FIG. 2A shows the waveform of the inspection output 15, and FIGS. 2B and 2C show the voltage waveform of the terminal voltage 7.

  The inspection apparatus shown in FIG. 1 includes a constant current power supply unit 5 having a changeover switch 4 for outputting different constant currents, and connection terminals 7 and 8 for supplying the current of the constant current power supply unit 5 to a capacitor. And a short-circuit switch 9 made of a switching element that short-circuits or opens the connection terminals 7 and 8, a voltage circuit 10 that measures the voltage of the connection terminal 7, and a control unit 19 such as a sequencer 16 that controls them. Become.

  Then, the constant current source 1 is selected and charged from the constant current power source 5 by the changeover switch 4 according to the capacity of the capacitor 6 connected to the connection terminals 7 and 8, and is smaller than the constant current source 1 after T time. The constant current source 2 is selected and further charged.

  In the constant current power supply unit 5, a constant current source 1 flows 30 mA, a constant current source 2 flows 1 mA, and a constant current source 3 flows 0.1 mA. The current of each constant current source is set according to the measured capacitor capacity.

  The operation of FIG. 1 will be described with reference to FIG. First, when the capacitor capacity is input by the key input 17, the input content is displayed on the display 18. If there is no mistake, the start is started from the key input 17. The short-circuit switch 9 connected in parallel with the capacitor 6 to be measured by the test output 15 of the voltage waveform shown in FIG. 2A from the sequencer 16 is opened, and at the same time, the sequencer 16 outputs from the sequencer 16 according to the capacitance value of the capacitor 6 to be measured. The constant current source 1 (30 mA) or the constant current source 2 (1 mA) is selected from the changeover switch 4 by the switching output 14 and charged.

  FIGS. 2B and 2C show voltage waveforms of the connection terminal 7. When the specified time T in FIG. 2B is charged, the changeover switch 4 in FIG. Switch to a small constant current source 3 (0.1 mA). Then, the measured voltage of the connection terminal 7 is compared with the voltage of the determination voltage source 11 by the voltage circuit 10 (the determination voltage source 11 and the comparator 12 in FIG. 1) that measures the voltage after t (ms).

  As shown in FIG. 2 (b), if the measured voltage 21 is higher than the voltage 20 of the voltage source for determination, the determination is acceptable, and if the determined voltage 22 is low as shown in FIG.

  The pass / fail result is input to the sequencer 16 by the pass / fail input signal 13 in FIG. 1, and processing such as ejection of a defective product and display of a defective count on the display 18 is performed.

  The switching time T of each constant current source is expressed by the following (Equation 1), where V2 is a determination voltage, I1 is a constant current for charging, I2 is a minimum constant current, R is a determination resistor, and C is a capacitor capacity. Desired.

  According to the above (Equation 1), since the time T varies depending on the capacitor capacitance C, it is necessary to change the switching time T of each constant current source by the sequencer 16 with the capacitance value by the key input 17.

  Here, assuming that C = 2500 μF, I1 = 30 mA, I2 = 0.1 mA, and determination resistance R = 1000Ω, calculating the charging time,

  From (Equation 2) and (Equation 3), it can be seen that a charging time of about 9 msec including + α is sufficient.

  As described above, since the capacitor inspection apparatus according to the first embodiment is charged with a low current of 30 mA, the voltage of the half-shorted capacitor does not increase, and can be determined as a defective product. can do.

(Embodiment 2)
Hereinafter, the second aspect of the present invention will be described in detail with reference to FIG.

  In the first embodiment, the comparator 12 constituting the voltage circuit 10 for measuring the voltage is replaced with the A / D converter 23. FIG. 3 shows a circuit configuration diagram of the inspection apparatus. Since the components other than the A / D converter 23 are the same, the same reference numerals are given. Further, only the different parts will be described in detail.

  In FIG. 3, the voltage after t (ms) is input to the pass / fail input of the sequencer 16 by the A / D converter 23. On the other hand, the calculated voltage value data T = CV2 / I when charging after T time from the capacitor capacity and the current value is obtained in advance, and the constant current power source according to the capacity of the capacitor 6 connected to the connection terminals 7 and 8 in FIG. The constant current source 1 (30 mA) is selected by the changeover switch 4 from the unit 5 and charged, and the constant current source 2 (1 mA) smaller than the constant current source 1 (30 mA) is selected after T time and further charged. If the determination voltage V2 ≦ V is reached after time t, it is determined to be acceptable, and a voltage less than that is determined to be unacceptable.

  As described above, by configuring the voltage circuit 10 of the capacitor inspection apparatus according to the second embodiment with the A / D converter 23, the voltage of the half short-circuited capacitor does not increase to the determination voltage V2, and is determined to be defective. Can be inspected in a short charge time. Further, by calculating and analyzing the data of the A / D converter 23 by the sequencer 16, there is an effect that the variation in the resistance level can be grasped.

(Embodiment 3)
Hereinafter, the third embodiment will be described in detail with respect to the present invention, particularly, the inventions described in claims 4 and 5.

  Since the circuit configuration of the inspection apparatus according to the third embodiment is the same as that of the inspection apparatus according to the first embodiment (FIG. 1), an inspection method different from the first embodiment will be described.

  The operation of FIG. 1 will be described with reference to FIG. First, when the capacitor capacity is input by the key input 17, the input content is displayed on the display 18. If there is no mistake, the start is started from the key input 17. The short-circuit switch 9 connected in parallel with the capacitor 6 to be measured by the voltage waveform inspection output 15 shown in FIG. 4A from the sequencer 16 is opened, and at the same time, depending on the capacitance value of the capacitor 6 to be measured, The constant current source 1 (30 mA) or the constant current source 2 (1 mA) is selected from the changeover switch 4 by the switching output 14 and charged.

  4B and 4C show voltage waveforms of the connection terminal 7. When the determination voltage 20 in FIG. 4B is exceeded, the constant current source smaller than the current charged by the switching output 14 by the switching output 14 is shown. 3 (0.1 mA). Then, the voltage of the connection terminal 7 is compared with the voltage of the determination voltage source 11 by the voltage circuit 10 (the determination voltage source 11 and the comparator 12 in FIG. 1) that measures the voltage again after t (ms).

  If the measured voltage 21 is higher than the voltage 20 of the determination voltage source 11 as shown in FIG. 4 (b), it is judged acceptable, and if the measured voltage 22 is low as shown in FIG. .

  The result of pass / fail is input to the sequencer 16 by the pass / fail input 13, and processing such as ejection of a defective product or display of a defective count on the display 18 is performed.

  When the measured voltage 22 does not reach the determination voltage 20, it is determined as a failure determination after waiting for a waiting time when the capacity is set to the maximum tolerance. The failure determination time TF of the constant current source is obtained from the following (Equation 4), where V2 is a determination voltage, I1 is a constant current for charging, and Cm is a maximum tolerance capacitor capacity.

  Needless to say, the determination level may be changed according to the actual state of the inspection.

  In the case of continuous production, continuous measurement can be performed by making the connection terminals 7 and 8 movable so that the capacitor leads are sequentially replaced and pinched or pressed.

  As described above, the capacitor inspection apparatus according to the third embodiment can accurately determine a half short-circuited capacitor by charging with a low current of 30 mA and then charging with a lower current.

(Embodiment 4)
Hereinafter, the fourth aspect of the present invention will be described in detail with reference to the fourth embodiment.

  Since the circuit configuration of the inspection apparatus according to the fourth embodiment is the same as that of the inspection apparatus according to the second embodiment (FIG. 3), an inspection method different from that of the second embodiment will be described.

  In FIG. 3, the voltage after t (ms) is input to the pass / fail input of the sequencer 16 by the A / D converter 23. On the other hand, the calculated voltage value when charging after T + t time is obtained in advance from the capacitor capacity and current value, the voltage data of the A / D converter 23 is compared with the calculated voltage value, and the measured voltage is higher than the calculated voltage value. If the measured voltage is low, it is judged as unacceptable.

The calculation voltage value is obtained from V ₁ ≦ (1 + a) It, V ₂ ≧ (1−a) It (a is an error and is usually 0.2), and the voltage data V of the A / D converter 23 The calculated voltage values V ₁ and V ₂ are compared, and if V ₁ ≦ V ≦ V ₂ , the pass voltage is determined, and other voltages are determined to be rejected.

As described above, by using the capacitor inspection apparatus according to the fourth embodiment, it is possible to determine whether the voltage V that has risen in a certain period of time is acceptable or not by using the calculated voltage values V ₁ and V _2. The electrolytic capacitor having a capacitance value and the electrolytic capacitor having a large capacitance value with a small voltage rise can also perform pass / fail judgment of the capacitance in a certain time.

  Note that a = 0.2 is set to 0.2 because the capacitance error of a normal electrolytic capacitor is ± 20%.

(Embodiment 5)
Hereinafter, the fifth embodiment of the present invention will be described in detail with reference to the fourth to sixth aspects of the present invention.

  In the fifth embodiment of the present invention, an A / D converter (analog-to-digital conversion) 23 is added to the voltage circuit 10 for measuring a voltage and an A / D input unit is added to the sequencer 16 in the first embodiment. . The circuit configuration of the inspection apparatus is shown in FIG.

  In addition, the same code | symbol is provided to the same part as the said Embodiment 1, and the detailed description demonstrates only a different part.

  The operation of FIG. 5 will be described below with reference to FIG. First, when the capacitor capacity is input by the key input 17, the input content is displayed on the display 18. If there is no mistake, the start is started from the key input 17. The short-circuit switch 9 connected in parallel to the capacitor 6 to be measured by the voltage waveform test output 15 shown in FIG. 6A from the sequencer 16 is opened, and at the same time, depending on the capacitance value of the capacitor 6 to be measured, The constant current source 1 (30 mA) or the constant current source 2 (1 mA) is selected from the changeover switch 4 by the switching output 14 and charged.

  FIGS. 6B and 6C show the voltage waveform of the connection terminal 7. The sequencer starts charging, and the voltage waveform of FIG. 6B is compared with the specified voltage 26 by the comparator 12. If it exceeds, the charging time starts counting, and the time T is charged, and the changeover switch 14 is switched to the constant current source 3 (0.1 mA) smaller than the charged current by the switching output 14. Then, after t (ms), it is input to the pass / fail input of the sequencer 16 by the A / D converter 23. On the other hand, the calculated voltage value when charging after T time is obtained in advance from the capacitor capacity and current value, the voltage data of the A / D converter 23 is compared with the calculated voltage value, and the measured voltage is higher than the calculated voltage value. If the measured voltage is low, it is judged as unacceptable.

  Depending on the result of pass / fail, processing such as ejection of a defective product and display of a defect count on the display 18 is performed. The specified voltage 26 is preferably low and is usually 50 mV or less.

  As described above, the inspection apparatus according to the fifth embodiment starts counting the time T based on the output of the comparator 12. Therefore, by comparing the timing with the inspection output 15, when there is a residual voltage in the capacitor or the connection terminal If there is a contact failure between the capacitor lead and the capacitor, it can be detected as an abnormality.

  In addition, by calculating and analyzing the data of the A / D converter 23 by the sequencer 16, there is an effect that the variation of the defect level can be grasped.

  Needless to say, in the above-described inspection apparatus, the same constant current source may be used for each capacity, and the saturation voltage may be measured to perform a half-short inspection. In addition, in the non-defective product determination product, the capacitance measurement may be performed based on the voltage data V or the time data T of the A / D converter 23.

  In this case, the capacity can be calculated using the relational expression C = IT / V.

  FIG. 7 shows an example of switching the constant current source of the constant current power supply unit 5 and displays the charging voltage after 100 ms at a constant current of 10 mA, 1 mA, and 100 μA according to capacity and current. If this voltage is equal to or higher than the voltage value of the saturation voltage for each resistance at a constant current, it is possible to discriminate with the discrimination resistance value in the table.

  In the constant current source, the maximum current value should not be set beyond the peak value from the voltage-current characteristics in the half-short state described in [Problems to be Solved by the Invention].

  INDUSTRIAL APPLICABILITY The present invention can provide an inspection apparatus capable of performing a short inspection or a capacity inspection at high speed before reflowing a capacitor in a short-circuited state, and making a pass / fail judgment. Used for capacitors.

Circuit configuration diagram of inspection apparatus according to Embodiment 1 and Embodiment 3 of the present invention Timing chart of configuration of embodiment 1 Circuit configuration diagram of inspection apparatus according to Embodiment 2 and Embodiment 4 of the present invention Timing chart according to Embodiment 3 of the present invention Circuit configuration diagram of an inspection apparatus according to Embodiment 5 of the present invention Timing chart of configuration of embodiment 5 The figure which shows the example of switching of the constant current source of this invention Partial detection circuit diagram of conventional electrolytic capacitor inspection equipment Voltage vs. current graph of electrolytic capacitor in half-short state (A) Time-current graph in conventional electrolytic capacitor inspection device, (b) Time-voltage graph

Explanation of symbols

1 Constant current source of 30 mA 2 Constant current source of 1 mA 3 Constant current source of 0.1 mA 4 Changeover switch 5 Constant current power supply unit 6 Capacitor to be measured 7 Connection terminal (+)
8 Connection terminal (-)
DESCRIPTION OF SYMBOLS 9 Short circuit switch 10 Voltage circuit which measures voltage 11 Judgment voltage source 12 Comparator 13 Pass / fail input signal 14 Switch output 15 Inspection output 16 Sequencer 17 Key input 18 Display 19 Control part

Claims (7)

A capacitor inspection device for inspecting the pass / fail of a capacitor by passing a current through the capacitor, or a capacitance, wherein the inspection device has a changeover switch for outputting different constant currents, and the constant current power supply unit. A connection terminal for energizing a capacitor for measuring the current of the current power supply unit, a short-circuit switch comprising a switching element for short-circuiting or opening the connection terminal, a voltage circuit for measuring the voltage of the connection terminal, and a sequencer for controlling them A capacitor including the control unit is connected to the connection terminal, the switch is selected according to the capacitor capacity, the current I is supplied from the constant current power supply unit, and the capacitor is charged. Capacitor inspection device, which performs pass / fail judgment of short circuit or capacitance inspection according to rise time or voltage rise time . 2. The capacitor inspection apparatus according to claim 1, wherein the voltage circuit includes a determination voltage source and a comparator, and compares the voltage of the connection terminal with the voltage of the determination voltage source. The capacitor inspection apparatus according to claim 1, wherein the voltage circuit comprises an A / D converter. A capacitor inspection device for inspecting the pass / fail of a capacitor by passing a current through the capacitor, or a capacitance, wherein the inspection device has a changeover switch for outputting different constant currents, and the constant current power supply unit. A connection terminal for energizing a capacitor for measuring the current of the current power supply unit, a short-circuit switch comprising a switching element for short-circuiting or opening the connection terminal, a voltage circuit for measuring the voltage of the connection terminal, and a sequencer for controlling them A capacitor including a control unit is connected to the connection terminal, a switch is selected according to the capacitor capacity, the current I is supplied from the constant current power supply unit, and the capacitor is charged. Later, a current II smaller than the current I is supplied to further charge the battery, and a pass / fail judgment is made based on voltage fluctuations after the T time. Testing apparatus of capacitors and performing capacity test. 5. The capacitor inspection apparatus according to claim 4, wherein the voltage circuit includes a determination voltage source and a comparator, and compares the voltage of the connection terminal with the voltage of the determination voltage source. The capacitor inspection apparatus according to claim 4, wherein the voltage circuit comprises an A / D converter. The capacitor inspection apparatus according to claim 1, wherein a plurality of constant current sources having different currents in a constant current power supply section of 0.1 to 30 mA are used.

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