JPS63119216A - Method and apparatus for identifying polarity of electrolytic capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method and device for determining the polarity of an electrolytic capacitor. More specifically, the present invention relates to a method and device for determining the polarity of an electrolytic capacitor, and more specifically, the present invention relates to a method and device for determining the polarity of an electrolytic capacitor mounted on a circuit board or the like together with other electronic components. The present invention relates to a discrimination method and a circuit board inspection device to which this method is applied.

[Conventional technology]

The polarity of the terminals or lead wires of aluminum foil dry electrolytic capacitors (hereinafter referred to as "electrolytic capacitors") is as follows:
The standard stipulates that markings must be made so that they can be clearly identified by visual inspection. For example, placing a black mark near the e-polarity terminal or lead wire outlet, or placing a black mark on the θ-polarity lead wire
An example of this is making the lead wire 10 mm or more shorter than the polar lead wire, but it is stipulated that a black mark must be placed even if the lead wire is shortened.

For this reason, in the manufacturing line of electrolytic capacitors, after the capacitor element is sealed in a metal case, it goes through an automatic inspection process to determine its polarity, and then processes such as the above-mentioned mark processing and lead wire lengthening/shortening processing are not included. and
For example, Japanese Patent Application No. 118825/1982 is known as one of the polarity discrimination circuits applied to the automatic inspection.

According to this proposal, DC voltage for measurement is applied to the terminals ■ and e of the electrolytic capacitor for positive (■, e) and reverse (e) terminals.

(2) The polarity of the terminal is determined by alternately switching and applying the DC voltage and detecting the potential between the midpoint of the DC voltage and the metal case.

[Problem that the invention seeks to solve]

The polarity determination circuit proposed above has the advantage that it can be measured in a relatively short time regardless of the capacitance of the electrolytic capacitor, and the determination can be made for positive or negative polarity. However, if resistance division is used to create the midpoint of the DC voltage, increasing the division resistance value will increase the input impedance of the detection circuit. (board tester), it is undesirable because it is easily affected by noise from peripheral components. Furthermore, when the dividing resistance value is made small, the divided current increases, and depending on the voltage capacity of the DC voltage source, it takes time for the voltage between the terminals of the electrolytic capacitor to reach a voltage sufficient for measurement.

The present invention has been made in view of the above points, and its purpose is to provide a method for determining the polarity of an electrolytic capacitor that does not particularly require the midpoint of the DC voltage for measurement, and a circuit board inspection device to which this determination method is applied. There is a particular thing.

[Means to solve the problem]

Referring to FIG. 1(A) showing an embodiment of the present invention, an electrolytic capacitor 1 has terminals 2 oriented in the same direction,
3, and is fixed to the pattern 6.7 of the circuit board 5 by soldering or the like. In order to determine the polarity of the electrolytic capacitor 1, a DC voltage source 8 applies a predetermined DC voltage to the terminal 2.3, and a signal generated in the metal case 4 of the electrolytic capacitor 1 by this DC voltage is transmitted via a probe 9. A measurement unit 10 is provided for taking out the sample and measuring its level.

Referring to FIG. 1B, this electrolytic capacitor 11 has, for example, lead wires 12.13 directed in opposite directions and is fixed by soldering or the like to a pattern 15.16 of the circuit board 5. This lead wire 12.13 has two wiring 1
DC voltage is applied from the DC voltage source 8 as in the case of FIG. The signal thus generated in the metal case 14 is extracted via the probe 17, and its level is measured in the measuring section 10.

[Effect]

In FIG. 1A, it is assumed that a DC voltage of the polarity shown is applied from the DC voltage source 8 to the electrolyte capacitor 1 at time t, for example. When the electrolytic capacitor 1 is properly attached to the circuit board 5, that is, when its polarity is the same as the applied DC voltage, the measured value of the current taken out from the metal case 4 is, for example, The result is as shown in FIG. 2(A). A relatively large inrush current occurs at time t, but it quickly attenuates, and thereafter a small leakage current is measured. Furthermore, when the voltage generated in the metal case 4 is measured, an extremely low level measurement value is obtained as shown in FIG. 3(A).

When the electrolytic capacitor 1 is mounted on the circuit board 5 in a reverse phase state, the measured values shown in FIG. 2(B) and FIG. 3(B), for example, are obtained. e of electrolytic capacitor
Since there is usually low impedance between the pole and the metal case,
After the inrush current attenuates, a relatively large leakage current flows (FIG. 2(B)), and a relatively high voltage is generated by the leakage current (FIG. 3(B)).

Regarding the electrolytic capacitor 11 in the direction opposite to the lead wire shown in FIG. 1(B), the measured current and voltage characteristics are almost the same as those in FIG. 1(A).

〔Example〕

Referring again to Figures 1 (A) and (B), when a DC voltage of 3 V is applied to the electrolytic capacitor 1 or 11 attached to a regular bowl, the steady current excluding the inrush current is A measured value of about 10μ8 or less was obtained almost regardless of the rated operating voltage or rated capacity of the capacitor. When installed with reverse polarity, a measured value of several tens of μA to several hundred μA can be obtained, depending on the type of electrolytic capacitor.

Regarding the measurement of generated voltage, for example, when applying a DC voltage of 0.4 V, the measured value obtained from an electrolytic capacitor installed in the normal state is about 50 mV or less, but from an electrolytic capacitor installed with the opposite polarity. A relatively high voltage slightly lower than the DC voltage of 0.4 V added above was measured. It is not necessary to perform both current measurement and voltage measurement for polarity determination, and polarity can be clearly determined using either one. In this embodiment, the voltage applied to the electrolytic capacitor was set to 0.4 V in the case of polarity determination by voltage measurement, for example, but since polarity determination is possible with a voltage lower than that, it may be set as appropriate.

In this embodiment, a general digital multimeter is used as the measurement unit 10, but any device that can measure current or voltage may be used. Further, the obtained measured value may be recorded on a printer, or the measured value may be displayed as OK or No on a display device, for example.

FIG. 4 shows an example in which a voltage of Φ, for example, is switched and applied from the DC voltage source 8 to the two terminals 2 and 3 of the electrolytic capacitor 1. In this case, the electrolytic capacitor 1 may be the electrolytic capacitor 11. In this embodiment as well, the polarity of the electrolytic capacitor can be determined by current measurement or voltage measurement similar to those shown in FIGS. 1(A) and 1(B).

FIG. 5 shows an example in which the electrolytic capacitor polarity determination method described above is applied to a circuit board testing device (hereinafter referred to as a "board tester").

That is, the circuit board 5 includes, for example, electrolytic capacitors 1 and 1.
1 is mounted with high density together with other electronic components (not shown), and its terminals 2, 3 and lead wires 12.13 are connected to circuit patterns 6.7 and 15, respectively, on the back side of the circuit board 5.
．． It is soldered to 16.

The circuit board 5 is movably placed, for example, via a guide member 22 and a spring 23 provided on the side of the pin board 21, and the circuit patterns 6, 7, .
Probes 25 to 29 are installed at positions facing the circuit patterns 15 and 16 and the grounding circuit pattern 24, respectively.

An electrically insulating board 31 is provided above the circuit board 5, and is driven in the direction of the arrow, that is, in the direction of the circuit board 5, by a pressurizing machine 30, for example. A rod-shaped member 32 is provided to push down the circuit board 5, and the capacitors 1, 1
Probes 33 and 34 that contact the metal cases 4 and 14 of 1
has been planted.

When the pressurizing machine 30 operates and moves in the direction of the arrow, the circuit board 5 is pushed down by the rod-shaped member 32, and each circuit pattern 6 to which the electrolytic capacitors 1 and 11 are soldered;
7', 15.16 and the grounding circuit pattern 24 are contacted by probes 25 to 29, respectively, and probes 33.34 on the insulating substrate 31 side are contacted to the metal cases 4, 14 of the electrolytic capacitors 1, 11.

In this state, for example, when a DC voltage is applied to the electrolytic capacitor 1 from the DC voltage source 8 (see Figure 1 above) on the board tester main body (not shown) via the probes 25 and 26, a current is generated in the metal case 4. A signal or voltage signal is taken out via the probe 33 and sent to the measuring section 10 (see FIG. 1 above) on the board tester main body (not shown) for measurement, and the polarity of the electrolytic capacitor 1 is determined based on the magnitude of the signal. be done. A DC voltage is applied to capacitor 11 via probes 27 and 28, and the current or voltage signal generated in its metal case 14 is extracted via probe 34. As a result, the measurement shown in FIG. 1(B) above is performed. In addition, probe 25
By applying voltages of constant polarity alternately to probes 26 and 26 or probes 27 and 28, the measurement shown in FIG. 4 is performed.

〔effect〕

As described above in detail, in the method for determining the polarity of an electrolytic capacitor according to the present invention, for example, a DC voltage is applied to a predetermined terminal of an electrolytic capacitor, and a current signal is generated between the metal case and the predetermined terminal. Or you can easily determine the polarity of the electrolytic capacitor by measuring the voltage signal.
and can be reliably determined.

In addition, in circuit board inspection equipment to which this polarity determination method is applied, for example, even when electrolytic capacitors are mounted with other electronic components at high density, there is no interference from other components such as noise. Polarity can be determined. Furthermore, even when electrolytic capacitors are connected in parallel, since the probe is provided in contact with the metal case, it is possible to determine the polarity of each individual capacitor without disconnecting the connection.

[Brief explanation of the drawing]

The attached drawings all relate to embodiments of the present invention, and include FIG.
A), (B) and Figure 4 are block diagrams of the polarity discrimination circuit, Figures 2 (A) and (B) are current characteristic diagrams of the electrolytic capacitor measured in Figures 1 and 4 above, Figure 3 (A),
(B) is a voltage characteristic diagram, and FIG. 5 is a diagram showing the main part of a polarity determining unit in a circuit board inspection apparatus to which the present invention is applied. In the figure, 1 and 11 are electrolytic capacitors, 2 and 3 are terminals, and 4.
14 is a metal case, 5 is a circuit board, 8 is a DC voltage source, 9
, 17.25 to 28.33.34 are probes, 1
0 is a measurement unit, 21 is a bin board, and 30 is a pressurizer.

Claims (4)

[Claims] (1) Apply a DC voltage to a predetermined terminal of an electrolytic capacitor consisting of a capacitor element sealed in a metal case, measure the current or voltage generated between the predetermined terminal and the metal case, and determine the polarity of the terminal. A method for determining the polarity of an electrolytic capacitor. (2) A method for determining polarity of an electrolytic capacitor according to claim (1), characterized in that a DC voltage of the same polarity is alternately applied to each terminal of the electrolytic capacitor. (3) A method for determining polarity of an electrolytic capacitor according to claim (1), characterized in that DC voltages of different polarities are simultaneously applied to each terminal of the electrolytic capacitor. (4) A circuit board on which an electrolytic capacitor having a metal case is mounted is brought close to a pin board, and a probe implanted in the pin board is brought into contact with a circuit pattern to which a terminal of the electrolytic capacitor is fixed to a predetermined position. In a circuit board inspection device that performs measurement, a first probe applies a DC voltage for measurement to a predetermined terminal of the electrolytic capacitor via the circuit pattern, and a first probe that contacts a metal case of the electrolytic capacitor to apply a voltage to the case. An apparatus for determining the polarity of an electrolytic capacitor, comprising: a second probe for extracting a generated current or voltage signal; and a polarity determining means for determining the polarity of the electrolytic capacitor based on the current or voltage signal.