KR102648218B1 - Inspection device and inspection method - Google Patents

Abstract

Provided is an inspection device and an inspection method that can inspect the insulation state between circuit patterns with high precision even when an electric cable has parasitic capacitance. The circuit pattern obtained by applying an inspection voltage between an electric cable connecting a printed circuit board to be inspected and an inspection device, a cancellation unit that cancels parasitic capacitance of the electric cable, and a circuit pattern of the printed circuit board through the electric cable. It is provided with a determination unit that determines whether the insulation state between the circuit patterns is good or bad, or whether a spark occurs between the circuit patterns, based on the voltage value between the circuit patterns or the current value flowing between the circuit patterns.

Description

Inspection device and inspection method {INSPECTION DEVICE AND INSPECTION METHOD}

The present invention relates to an inspection device and an inspection method.

Conventionally, in a printed board having a plurality of wiring patterns, the good or bad state of insulation of each wiring pattern from other wiring patterns (whether or not sufficient insulation is secured) is determined by an insulation inspection device, so that the printed board Insulation inspection is performed to check whether the product is a good product (for example, patent document 1).

In Patent Document 1, the insulation state between circuit patterns on a printed board is inspected by applying a voltage between the circuit patterns. In other words, the insulation state of one circuit pattern and the other circuit pattern is inspected by applying a voltage to one circuit pattern and inspecting the current flowing through the other circuit pattern. In such an insulation inspection device, for example, the circuit pattern of a printed board is connected through an inspection probe provided at the tip of an electric cable. The insulation test device applies a test voltage to the circuit pattern through an electric cable and test probe. The insulation inspection device checks whether the insulation is in good condition based on the insulation resistance value calculated from the voltage value between circuit patterns and the current value flowing through the electric cable.

Additionally, the insulation inspection device performs spark detection simultaneously with the insulation inspection. Sparking here is a phenomenon in which insulation breakdown occurs due to a potential difference between circuit patterns and current flows instantaneously between circuit patterns. An insulation test device measures the voltage between circuit patterns or the current flowing between circuit patterns at a predetermined spark detection time during the insulation test process. The insulation inspection device determines that a spark has occurred when a so-called drop voltage occurs, in which the voltage between circuit patterns decreases by more than a predetermined value. Alternatively, the insulation inspection device determines that a spark has occurred when a so-called spark current occurs where the current flowing between circuit patterns increases by more than a predetermined value.

Japanese Patent No. 5727976 Publication

However, there are cases where the current value flowing through the circuit pattern or the voltage value applied to the circuit pattern cannot be accurately measured due to the parasitic capacitance of the electric cable. For this reason, there was a problem that it became difficult to accurately inspect whether the insulation condition was good.

The present invention provides an inspection device and an inspection method that can accurately inspect the insulation state between circuit patterns or the presence or absence of sparks between circuit patterns even when there is parasitic capacitance in an electric cable.

In order to solve the above-described problem, one aspect of the present invention includes an electric cable connecting a printed circuit board to be inspected and an inspection device, a cancellation unit that cancels the parasitic capacitance of the electric cable, and the electric cable through the electric cable. Based on the voltage value between the circuit patterns obtained by applying a test voltage between the circuit patterns of the printed board, or the current value flowing between the circuit patterns, whether the insulation state between the circuit patterns is good or bad, or whether sparks are generated between the circuit patterns. It is an inspection device including a determination unit that determines.

Furthermore, one aspect of the present invention is an inspection method of an inspection device including a canceling unit that cancels the parasitic capacitance of an electric cable connecting a printed circuit board to be inspected and the inspection device, wherein the determination unit is configured to print the printed circuit board through the electric cable. Based on the voltage value between the circuit patterns obtained by applying a test voltage between the circuit patterns of the board, or the current value flowing between the circuit patterns, the good or bad insulation state between the circuit patterns, or the presence or absence of sparks between the circuit patterns, is determined. It is a testing method for making judgments.

According to the present invention, the state of insulation between circuit patterns or the presence or absence of sparks between circuit patterns can be inspected with high precision.

1A and 1B are block diagrams showing a configuration example of the insulation inspection system 1 of the first embodiment.
2A, 2B, and 2C are block diagrams showing a configuration example of the insulation inspection system 1A of the second embodiment.
3A and 3B are block diagrams showing a modified example of the insulation inspection system 2 of the third embodiment.
4A, 4B, and 4C are block diagrams showing a configuration example of the insulation inspection system 2A of the fourth embodiment.
Figure 5 is a block diagram showing a configuration example of a conventional insulation inspection system 500.
Figure 6 is a block diagram showing a configuration example of a conventional insulation inspection system 600.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention will be described with reference to the drawings.

(Conventional insulation inspection system (500))

First, a conventional insulation inspection system 500 will be described. FIG. 5 is a block diagram showing a configuration example of the insulation inspection system 500. The insulation inspection system 500 includes, for example, a conventional inspection device JS1 and a printed board 30. The printed board 30 is a board on which a circuit pattern to be inspected for insulation inspection is printed.

The conventional inspection device JS1 is connected to the circuit pattern 300 of the printed board 30 through an electric cable 110. Additionally, the conventional inspection device JS1 is connected to the circuit pattern 310 of the printed board 30 through an electric cable 120. Here, the circuit pattern 300 and the circuit pattern 310 are different circuit patterns printed on the same printed board 30.

The conventional inspection device JS1 includes, for example, a voltage source VDD, an ammeter A1, a resistor R1, an electric cable 110, an electric cable 120, a voltmeter V, an ammeter A2, and a determination unit 150. Equipped with The voltage source VDD is a voltage source that applies a predetermined test voltage to the circuit pattern 300, and is, for example, a variable voltage source. Additionally, a current source may be provided instead of the voltage source VDD. In this case, the current source supplies a predetermined current to the circuit pattern 300.

The ammeter A1 detects the current flowing through the high potential side (Highside) in the conventional inspection device JS1. Resistance R1 is the resistance between the ammeter A1 and the circuit pattern 300. The voltmeter V detects the voltage applied to the circuit pattern 300. The electric cable 110 electrically connects the circuit pattern 300 and the high-potential side measurement end (point indicated by a black circle in FIG. 5) in the conventional inspection apparatus JS1. The electric cable 120 electrically connects the circuit pattern 310 and the low-potential side (Lowside) measurement end (point indicated by a black circle in FIG. 5) in the conventional inspection apparatus JS1. The ammeter A2 detects the current flowing through the low-potential side in the conventional inspection device JS1. In addition, when applying a voltage to a plurality of circuit boards on the printed board 30, a plurality of circuit patterns different from the plurality of circuit patterns, a plurality of circuit patterns different from one circuit pattern, or a plurality of circuit patterns different from the plurality of circuit patterns There are cases where voltage is applied between circuit patterns.

The electric cable 110 includes a central conductor 111 and a shield conductor 112. The central conductor 111 connects the measurement end on the high potential side and the circuit pattern 300. The central conductor 111 is insulated and coated with an insulator such as polyethylene. The shield conductor 112 is provided in a cylindrical shape to cover the insulator covering the central conductor 111 with an insulating film. The shield conductor 112 is connected (grounded) to ground GND.

The electric cable 120 includes a central conductor 121 and a shield conductor 122. Since the central conductor 121 and the shield conductor 122 in the electric cable 120 have the same structure as the central conductor 111 and the shield conductor 112 in the electric cable 110, the explanation omit. The central conductor 121 connects the circuit pattern 310 and the measurement end on the low-potential side. The shield conductor 122 is connected (grounded) to ground GND.

The determination unit 150 is realized by executing a program stored in the storage unit by a processor such as a CPU (Central Processing Unit) in the conventional inspection device JS1 as a computer device. The determination unit 150 includes a voltage control circuit that is connected to the voltage source VDD and controls the voltage source VDD. The determination unit 150 is connected to each of the ammeters A1 and A2, and acquires the current values measured by the ammeters A1 and A2. The determination unit 150 is connected to a voltmeter V and acquires the voltage value measured by the voltmeter V.

The determination unit 150 applies a voltage between circuit patterns of the printed board 30 (between the circuit patterns 300 and 310) through the electric cable 110. The determination unit 150 detects the current value flowing between circuit patterns. For example, when the insulation between the circuit pattern 300 and the circuit pattern 310 is sufficient, even if a voltage is applied to the circuit pattern 300, almost no current flows through the circuit pattern 310. When the insulation state of the circuit pattern 300 and the circuit pattern 310 is insufficient, when a voltage is applied to the circuit pattern 300, a larger current flows through the circuit pattern 310 than when the insulation state is sufficient. In this case, the insulation resistance value between circuit patterns is lower than when the insulation state is sufficient. Using these properties, the determination unit 150 performs an insulation test.

Here, the determination unit 150 performs spark detection in the process of insulation inspection. The determination unit 150 performs spark detection by detecting a voltage drop between circuit patterns or an increase in the current value flowing between circuit patterns, which occurs when a spark occurs. In the following description, the waveform representing the time series change in the current value that increases instantaneously when a spark is generated is referred to as a “spark waveform.” Additionally, the current value that increases instantaneously when a spark occurs is called “spark current.” Additionally, the maximum value of spark current is called “peak current.”

For example, when a voltage is applied between circuit patterns, the determination unit 150 determines whether the current value of the peak current flowing between circuit patterns at a predetermined detection time is greater than or equal to a predetermined threshold. The detection time is a predetermined time period starting from the point in time when the voltage starts to rise after voltage application. The current value in this case may be detected by either the ammeter A1 or A2. Additionally, the determination unit 150 may make a determination based on the current values of both the ammeters A1 and A2.

The determination unit 150 determines that a spark has occurred when a current exceeding the threshold value flows. Meanwhile, the determination unit 150 determines that no spark has occurred when the current value flowing between circuit patterns is less than a predetermined threshold value. That is, the determination unit 150 determines whether or not sparks are generated between circuit patterns based on the current value flowing between circuit patterns obtained by applying a test voltage between circuit patterns.

In addition, in the above description, the case where the determination unit 150 determines whether or not a spark has occurred based on the current value flowing between circuit patterns was described as an example. However, it is not limited to this. The determination unit 150 may determine whether sparks are generated between circuit patterns based on the voltage value (drop amount of voltage value, etc.) applied between circuit patterns.

(Conventional insulation inspection system (600))

Next, a conventional insulation inspection system 600 will be described. FIG. 6 is a block diagram showing a configuration example of a conventional insulation inspection system 600. The conventional insulation inspection system 600 differs from the insulation inspection system 500 in that the electric cable connecting the device and the printed board 30 is a two-core cable (two center conductors). In the following description, only differences from the insulation inspection system 500 will be described, and descriptions of configurations similar to the insulation inspection system 500 will be omitted.

The insulation inspection system 600 includes, for example, a conventional inspection device JS2 and a printed board 30. The conventional inspection device JS2 is connected to the circuit patterns 300 and 310 of the printed board 30 through an electric cable 210.

The conventional inspection device JS2 includes, for example, a voltage source VDD, an ammeter A3, a resistor R2, an electric cable 210, a voltmeter V, an ammeter A4, and a determination unit 250. Among these, the voltage source VDD, ammeter A3, resistor R2, voltmeter V, ammeter A4, and each element of the determination unit 250 are voltage source VDD, ammeter A1, resistor R1, and It is the same as each element of the voltmeter V, ammeter A2, and determination unit 150. For this reason, the explanation is omitted.

The electric cable 210 is a two-core cable. That is, the electric cable 210 electrically connects the circuit pattern 300 to the high-potential side measurement end (point indicated by a black circle in FIG. 6) in the conventional inspection apparatus JS2. In addition, the electric cable 210 electrically connects the circuit pattern 310 and the low-potential side (Lowside) measurement end (point indicated by a black circle in FIG. 6) of the conventional inspection device JS2.

The electric cable 210 includes a high-potential side central conductor 211, a low-potential side central conductor 212, and a shield conductor 213. The high-potential side central conductor 211 connects the high-potential side measurement end and the circuit pattern 300. The high-potential side central conductor 211 is insulated with an insulator such as polyethylene. The low-potential side central conductor 212 connects the circuit pattern 310 and the low-potential side measurement end. The low-potential side central conductor 212 is insulated with an insulator such as polyethylene. The shield conductor 213 is provided in a cylindrical shape so as to cover both the insulating film on the high-potential side central conductor 211 and the insulating film on the low-potential side central conductor 212. The shield conductor 213 is connected to ground GND, for example.

Generally, in an electric cable, a shield conductor and a center conductor are provided close to each other. For this reason, the center conductor and shield conductor may unintentionally function as a condenser. In other words, there was a possibility that this unintended capacitance of the condenser could become a parasitic capacitance of the electric cable. Whether it is a single-core (one center conductor) electric cable in the conventional inspection apparatus JS1 or a two-core electric cable in the conventional inspection apparatus JS2, the fact that parasitic capacitance is generated in the electric cable is the same.

In Fig. 5, when a test voltage is applied between circuit patterns, it is conceivable that current flows through roots RT2 and RT3 in addition to root RT1 due to parasitic capacitance. Route RT1 is a path through which current is originally assumed to flow during inspection. Route RT2 is a path through which current is believed to flow from the central conductor 111 to the shield conductor 112 through the parasitic capacitance KY1 of the electric cable 110. Route RT3 is a path through which current is believed to flow from the central conductor 121 to the shield conductor 122 through the parasitic capacitance KY2 of the electric cable 120.

In Fig. 6, when a test voltage is applied between circuit patterns, it is possible that current flows through roots RT11 and RT12 in addition to root RT10. Route RT10 is a path through which current is originally assumed to flow during inspection. The route RT11 is a path through which the current is believed to flow from the high-potential side central conductor 211 to the shield conductor 213 through the parasitic capacitance KY3 between the high-potential side central conductor 211 and the shield conductor 213. Route RT12 is a path through which current is believed to flow from the low-potential side central conductor 212 to the shield conductor 213 through the parasitic capacitance KY4 between the low-potential side central conductor 212 and the shield conductor 213.

In this way, due to the presence of parasitic capacitance in the electric cable, it was difficult to accurately detect the current value flowing between circuit patterns during inspection. In addition, the presence of parasitic capacitance in the electric cable slowed down the slope of the change in current value, potentially slowing down the waveform. For this reason, in insulation inspection, it takes time for the current flowing between circuit patterns to stabilize, which is a factor in increasing the inspection time. Additionally, even in cases where a spark occurred, there were cases where the spark waveform was buried in the parasitic capacitance and the instantaneous increase in current value was not visible, making it impossible to detect the spark.

As a countermeasure to this, in this embodiment, the parasitic capacitance of the electric cable is made to seemingly disappear. That is, in this embodiment, the parasitic capacitance of the electric cable is removed (cancelled). Hereinafter, with respect to this embodiment, the first to fourth embodiments will be described in order.

(First Embodiment)

The insulation inspection system 1 according to the first embodiment will be described. 1A and 1B are block diagrams showing a configuration example of the insulation inspection system 1 of the first embodiment. In the insulation inspection system 1, the parasitic capacitance of the electric cable 110 in the conventional inspection device JS1 is apparently canceled.

As shown in FIG. 1A, the insulation inspection system 1 includes an inspection device 10 and a printed board 30. The inspection device 10 includes a voltage source VDD, an ammeter A1, a resistor R1, a voltmeter V, a connection portion 100, a buffer B, an electric cable 110, an electric cable 120, and an ammeter A2. , and is provided with a determination unit 150. Among these, each element of the voltage source VDD, ammeter A1, resistor R1, voltmeter V, electric cable 120, ammeter A2, and determination unit 150 has the same sign in the conventional inspection device JS1. It is the same as each given element. For this reason, the explanation is omitted.

In this embodiment, the central conductor 111 and the shield conductor 112 of the electric cable 110 are connected by the connecting portion 100 via the buffer B. That is, the connection portion 100 connects the central conductor 111 and the shield conductor 112. Here, the connection unit 100 is an example of a “cancellation unit.”

As a result, the potential of the shield conductor 112 becomes the same as the potential of the central conductor 111. For this reason, the current resulting from the potential difference between the potential of the shield conductor 112 and the potential of the central conductor 111 does not flow. Therefore, the parasitic capacitance (capacitance indicated by symbol CM1) occurring between the shield conductor 112 and the central conductor 111 can be ignored, and the parasitic capacitance is apparently canceled.

Additionally, as shown in FIG. 1B, the central conductor 111 and the shield conductor 112 of the electric cable 110 may be directly connected without a buffer intervening.

If the parasitic capacitance of the electric cable 110 is canceled, no current flows through the path of root RT2 in FIG. 5 when the inspection voltage is applied between patterns. In other words, compared to the conventional system shown in FIG. 5, it becomes possible to detect the current value flowing between circuit patterns during inspection with greater precision.

(Second Embodiment)

The insulation inspection system 1A according to the second embodiment will be described. 2A, 2B, and 2C are block diagrams showing a configuration example of the insulation inspection system 1A of the second embodiment. In the insulation inspection system 1, the parasitic capacitance of the electric cable 120 in the conventional inspection device JS1 is apparently canceled.

As shown in FIG. 2A, the insulation inspection system 1A includes an inspection device 10A and a printed board 30. The inspection device 10A includes a voltage source VDD, an ammeter A1, a resistor R1, a voltmeter V, an electric cable 110, an electric cable 120, a virtual ground circuit 130, an ammeter A20, and a plate. Equipped with government (150). Among these, the elements of the voltage source VDD, ammeter A1, resistor R1, voltmeter V, and electric cable 110 are the same as the elements given the same symbols in the conventional inspection device JS1. For this reason, the explanation is omitted. Although the ammeter A20 is shown in a different diagram from the ammeter A2 in FIG. 5 in FIG. 2A, it has the same function as the ammeter A2 and detects the current flowing through the low-potential side of the inspection device 10A.

In this embodiment, the central conductor 121 of the electric cable 120 is connected to the virtual ground circuit 130. The virtual ground circuit 130 is a negative feedback circuit constructed using an operational amplifier, and is a circuit that functions so that the potential of the input terminal of the operational amplifier becomes the same potential. In the virtual ground circuit 130, the non-inverting input terminal (+) of the operational amplifier is connected to ground GND. As a result, the central conductor 121 is maintained at the same potential as the ground GND. Here, the virtual ground circuit 130 is an example of a “cancellation unit.”

As a result, the potential of the central conductor 121 becomes the same as the potential of the shield conductor 122. For this reason, the current resulting from the potential difference between the potential of the center conductor 121 and the potential of the shield conductor 122 does not flow. Therefore, the parasitic capacitance (capacitance indicated by symbol CM2) occurring between the central conductor 121 and the shield conductor 122 can be ignored, and the parasitic capacitance is apparently canceled.

If the parasitic capacitance of the electric cable 120 is canceled, no current flows through the path of the root RT3 in FIG. 5 when the inspection voltage is applied between patterns. In other words, compared to the conventional system shown in FIG. 5, it becomes possible to detect the current value flowing between circuit patterns during inspection with greater precision.

Additionally, the insulation inspection system 1A may be provided with the connection portion 100 shown in FIGS. 1A and 1B. That is, the insulation inspection system 1A is configured to include both a connection portion 100 that cancels the parasitic capacitance of the electric cable 110 and a virtual ground circuit 130 that cancels the parasitic capacitance of the electric cable 120. You can continue.

In addition, as shown in FIG. 2B, in order to apparently cancel the parasitic capacitance of the electric cable 120, instead of providing the virtual ground circuit 130, the same connection portion 100 as the connection portion 100 of the first embodiment is used. -1) may be provided on the low potential side. That is, a connection portion is provided to connect the central conductor 121 and the shield conductor 122 via a buffer. This connection unit 100-1 is also an example of a “cancellation unit.”

Additionally, as shown in FIG. 2C, in order to apparently cancel the parasitic capacitance of the electric cable 120, the central conductor 121 and the shield conductor 122 may be connected directly without a buffer intervening.

(Third Embodiment)

The insulation inspection system 2 according to the third embodiment will be described. 3A and 3B are block diagrams showing a configuration example of the insulation inspection system 2 of the third embodiment. In the insulation inspection system 2, the parasitic capacitance of the electric cable 210 in the conventional inspection device JS2 is apparently canceled.

As shown in FIG. 3A, the insulation inspection system 2 includes an inspection device 20 and a printed board 30. The inspection device 20 includes a voltage source VDD, an ammeter A3, a resistor R2, a voltmeter V, a connection unit 200, a buffer B, an electric cable 210, an ammeter A4, and a determination unit 250. Equipped with Among these, the elements of the voltage source VDD, ammeter A3, resistor R2, voltmeter V, and determination unit 250 are the same as the elements given the same symbols in the conventional inspection device JS2. For this reason, the explanation is omitted.

In this embodiment, the high-potential side central conductor 211 and the shield conductor 213 of the electric cable 210 are connected by the connection portion 200 via the buffer B. That is, the connection portion 200 connects the high-potential side central conductor 211 and the shield conductor 213. Here, the connection unit 200 is an example of a “cancellation unit.”

As a result, the potential of the high-potential side central conductor 211 becomes the same potential as the potential of the shield conductor 213. For this reason, the current resulting from the potential difference between the potential of the high-potential side central conductor 211 and the potential of the shield conductor 213 does not flow. Therefore, the parasitic capacitance (capacitance indicated by symbol CM3) occurring between the high-potential side central conductor 211 and the shield conductor 213 can be ignored, and the parasitic capacitance is apparently canceled.

Additionally, as shown in FIG. 3B, the high-potential side central conductor 211 and the shield conductor 213 of the electric cable 210 may be directly connected without a buffer intervening.

If the parasitic capacitance of the electric cable 210 is canceled, no current flows through the path of the root RT11 in FIG. 6 when the inspection voltage is applied between patterns. That is, compared to the conventional system shown in FIG. 6, it becomes possible to detect the current value flowing between circuit patterns during inspection with greater precision.

(Fourth Embodiment)

The insulation inspection system 2A according to the fourth embodiment will be described. 4A, 4B, and 4C are block diagrams showing a configuration example of the insulation inspection system 2A of the fourth embodiment. In the insulation inspection system 2A, the parasitic capacitance of the electric cable 210 in the conventional inspection device JS2 is apparently canceled.

As shown in FIG. 4A, the insulation inspection system 2A includes an inspection device 20A and a printed board 30. The inspection device 20A is provided with a voltage source VDD, an ammeter A3, a resistor R2, a voltmeter V, an electric cable 210, a virtual ground circuit 230, and an ammeter A40. Among these, the elements of the voltage source VDD, ammeter A3, resistor R2, and voltmeter V are the same as the elements given the same symbols in the conventional inspection device JS2. For this reason, the explanation is omitted. Although the ammeter A40 is shown in a different figure from the ammeter A4 in FIG. 6 in FIG. 4A, it has the same function as the ammeter A4 and detects the current flowing through the low-potential side of the inspection device 20A.

In this embodiment, the low-potential side central conductor 212 of the electric cable 210 is connected to the virtual ground circuit 230. The virtual ground circuit 230 is the same as the virtual ground circuit 130 of the inspection device 10A. For this reason, the explanation is omitted. In the virtual ground circuit 230, the non-inverting input terminal (+) of the operational amplifier is connected to ground GND. As a result, the low-potential side central conductor 212 is maintained at the same potential as the ground GND. Here, the virtual ground circuit 230 is an example of a “cancellation unit.”

As a result, the potential of the low-potential overlap conductor 212 becomes the same potential as the potential of the shield conductor 213. For this reason, the current resulting from the potential difference between the potential of the low-potential side central conductor 212 and the potential of the shield conductor 213 does not flow. Therefore, the parasitic capacitance (capacitance indicated by symbol CM4) occurring between the low-potential side central conductor 212 and the shield conductor 213 can be ignored, and the parasitic capacitance is apparently canceled.

If the parasitic capacitance of the electric cable 210 is canceled, no current flows through the path of RT12 in FIG. 6 when a test voltage is applied between patterns. In other words, compared to the conventional system shown in FIG. 6, it becomes possible to detect the current value flowing between circuit patterns during inspection with greater precision.

In addition, as shown in FIG. 4B, in order to apparently cancel the parasitic capacitance of the electric cable 210, instead of providing the virtual ground circuit 230, the same connection portion 200 as the connection portion 200 of the third embodiment is used. -1) may be provided on the low potential side. That is, a connection portion is provided to connect the low-potential side central conductor 212 and the shield conductor 213 via a buffer. This connection unit 200-1 is also an example of a “cancellation unit.”

Additionally, as shown in FIG. 4C, in order to cancel the parasitic capacitance of the electric cable 210, the low-potential side central conductor 212 and the shield conductor 213 may be directly connected without a buffer intervening.

As described above, the inspection device 10 of the first embodiment shown in FIG. 1A includes an electric cable 110, a connection portion 100, and a determination portion 150. The electric cable 110 connects the printed board 30 and the inspection device 10. The electric cable 110 includes a shield cable in which a central conductor 111, an insulator that insulates and coats the central conductor 111, and a shield conductor 112 that covers the insulator are disposed. In the electric cable 110, the central conductor 111 is connected to the high potential side between circuit patterns. The connection portion 100 connects the central conductor 111 and the shield conductor 112. The determination unit 150 determines whether the insulation state between circuit patterns is good or bad. The determination unit 150 applies a test voltage between circuit patterns of the printed board 30 through the electric cable 110. The determination unit 150 determines whether the insulation state is good or bad based on the voltage value between circuit patterns obtained by applying a test voltage or the current value flowing between the circuit patterns.

As a result, in the inspection device 10 of the first embodiment, the central conductor 111 and the shield conductor 112 are connected. For this reason, the parasitic capacitance of the electric cable 110 is apparently canceled. This makes it possible to accurately detect the current value flowing between circuit patterns during inspection. Therefore, even when there is parasitic capacitance in the electric cable 110, the insulation state between circuit patterns can be inspected with high precision.

Additionally, by canceling the parasitic capacitance of the electric cable 110, it becomes possible to shorten the time until the applied voltage rises. As a result, the time required for inspection can be shortened, and the efficiency of inspection can be improved.

Additionally, conventionally, the frequency characteristics of the measurement path deteriorated due to the parasitic capacitance of the electric cable 110. The measurement path here is a path through which current flows by voltage application. Here, the worsening of the frequency characteristics means that the high-range characteristics deteriorate and the time constant of the current flowing through the measurement path increases. In contrast, in this embodiment, the parasitic capacitance of the electric cable 110 is canceled. Thereby, the frequency characteristics of the measurement path are improved. The improvement in frequency characteristics here means that the high-range characteristics are improved, the decrease in the rate of change of the current flowing through the measurement path is suppressed, and the rate of change of the current becomes faster compared to the prior art. As a result, the high-frequency waveform of the spark current measured by the ammeter A1 or the ammeter A20 becomes sharp, making it possible to improve the measurement accuracy of the peak current.

Additionally, by canceling the parasitic capacitance of the electric cable 110, it becomes possible to detect the peak of the spark waveform that was buried in the parasitic capacitance in the conventional inspection. That is, in the past, the spark waveform was slowed down due to parasitic capacitance, and the peak was buried without being detected. In this embodiment, by canceling the parasitic capacitance of the electric cable 110, the rise of the waveform becomes sharper than before, making it possible to detect peaks that were buried conventionally.

Additionally, the inspection device 10A of the second embodiment shown in FIG. 2A includes an electric cable 120, a virtual ground circuit 130, and a determination unit 150. The electric cable 120 connects the printed board 30 and the inspection device 10A. The electric cable 120 includes a shield cable in which a central conductor 121, an insulator that insulates and coats the central conductor 121, and a shield conductor 122 that covers the insulator are disposed. In the electric cable 120, the central conductor 121 is connected to the low-potential side between circuit patterns. Shield conductor 122 is grounded. The virtual ground circuit 130 is connected to the central conductor 121. As a result, in the inspection device 10A of the second embodiment, the parasitic capacitance of the electric cable 120 is apparently canceled. Therefore, the same effect as the effect described above is achieved.

Additionally, the inspection device 20 of the third embodiment shown in FIG. 3A includes an electric cable 210, a connection portion 200, and a determination portion 250. The electric cable 210 connects the printed board 30 and the inspection device 20. The electric cable 210 includes a shield cable in which a high-potential side central conductor 211, a low-potential side central conductor 212, an insulator, and a shield conductor 213 are disposed. The insulator insulates and coats each of the high-potential side central conductor 211 and the low-potential side central conductor 212. Shield conductor 213 covers the insulator. The high-potential side central conductor 211 is connected to the high-potential side between circuit patterns. The low-potential side central conductor 212 is connected to the low-potential side between circuit patterns. The connection portion 200 connects the high-potential side central conductor 211 and the shield conductor 213. As a result, in the inspection device 20 of the third embodiment, the parasitic capacitance of the electric cable 210 is apparently canceled. Therefore, the same effect as the effect described above is achieved.

Additionally, the inspection device 20A of the fourth embodiment shown in FIG. 4A includes an electric cable 210, a virtual ground circuit 230, and a determination unit 250. The high-potential side central conductor 211 is connected to the high-potential side between circuit patterns. The low-potential side central conductor 212 is connected to the low-potential side between circuit patterns. Shield conductor 213 is grounded. The virtual ground circuit 230 is connected to the low-potential side central conductor 212. As a result, in the inspection device 20A of the fourth embodiment, the parasitic capacitance of the electric cable 210 is apparently canceled. Therefore, the same effect as the effect described above is achieved.

Additionally, in the above-described embodiment, the expression “connected (grounded) to ground GND” is used. The potential of the ground GND (ground potential) in this case is not limited to the case where it represents the absolute potential 0 [V]. That is, the ground potential includes the intermediate potential (intermediate potential) of the power supply of the circuit in the inspection device. The intermediate potential means the potential between the potential on the high potential side and the potential on the low potential side of the power supply. For example, the intermediate potential is 7.5 [V] when the high potential side of the power supply is 15 [V] and the low potential side is 0 [V]. The ground GND may be this intermediate potential of 7.5 [V], or may be any potential between 15 [V] on the high potential side and 0 [V] on the low potential side.

Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, as well as the invention described in the claims and their equivalents.

1: Insulation inspection system
10: Inspection device
100, 100-1: Connection part
110: electric cable
111: center conductor
112: shield conductor
120: electric cable
121: center conductor
122: shield conductor
130: Virtual ground circuit
200, 200-1: Connection part
210: Electric cable
211: High potential side center conductor
212: Low-potential side center conductor
213: shield conductor

Claims (12)

An electric cable connecting the printed circuit board to be inspected and the inspection device,
a cancellation unit that cancels parasitic capacitance of the electric cable;
Based on the voltage value between the circuit patterns obtained by applying a test voltage between the circuit patterns of the printed board through the electric cable, or the current value flowing between the circuit patterns, the insulation state between the circuit patterns is good or bad, or the circuit Judgment unit that determines whether sparks occur between patterns
Equipped with
The electric cable is a shield cable including a high-potential side central conductor, a low-potential side central conductor, an insulator that insulates and coats each of the high-potential side central conductor and the low-potential side central conductor, and a shield conductor that covers the insulator. An inspection device comprising: the high-potential side central conductor is connected to the high-potential side between the circuit patterns, and the low-potential side central conductor is connected to the low-potential side between the circuit patterns. According to paragraph 1,
The inspection device wherein the cancellation unit is a connection unit that brings the high-potential side central conductor and the shield conductor to the same potential. According to paragraph 2,
The cancellation unit is a connection unit that connects the high-potential side central conductor and the shield conductor. According to paragraph 1,
The shield conductor is brought to ground potential,
The inspection device wherein the cancellation unit is a virtual ground circuit that virtually grounds the low-potential side central conductor. According to paragraph 1,
The inspection device is wherein the cancellation unit is a connection unit that brings the low-potential side center conductor and the shield conductor to the same potential. According to clause 5,
The inspection device wherein the cancellation unit is a connection unit that connects the low-potential side central conductor and the shield conductor. It is an inspection method of an inspection device including an electric cable connecting the printed circuit board to be inspected and the inspection device,
The electric cable is a shield cable including a high-potential side central conductor, a low-potential side central conductor, an insulator that insulates and coats each of the high-potential side central conductor and the low-potential side central conductor, and a shield conductor that covers the insulator. It includes: the high-potential side central conductor is connected to the high-potential side between the circuit patterns of the printed board, and the low-potential side central conductor is connected to the low-potential side between the circuit patterns,
The cancellation unit cancels the parasitic capacitance of the electric cable connecting the printed circuit board to be inspected and the inspection device,
The determination unit determines whether the insulation state between the circuit patterns is good or bad, based on a voltage value between the circuit patterns obtained by applying a test voltage between the circuit patterns of the printed board through the electric cable, or a current value flowing between the circuit patterns, Or determining the presence or absence of sparks between the circuit patterns,
method of inspection. delete delete delete delete delete