KR102004842B1 - Insulation tester of printed circuit board and insulation test method - Google Patents

Abstract

A DC voltage is applied between the circuit patterns C1 to C4 of the printed circuit board 1 and a defect in the insulation state of the printed board is detected based on the resistance value between the applied voltage value and the circuit pattern calculated from the current value flowing between the circuit patterns (7) for detecting a current flowing between circuit patterns by the application of a voltage, and a current detecting section (7) for detecting a current flowing between the circuit patterns (9) for detecting whether or not a current value detected by the current detecting section (7) due to a spark occurring between circuit patterns has increased by a predetermined value or more within a spark detection time of the current detection section A spark judging unit (25) for judging that the printed board is defective when an increase is detected, and a spark judging unit It has an output time setting unit (10).

Description

TECHNICAL FIELD [0001] The present invention relates to an insulated inspecting apparatus and an insulation inspecting method for a printed circuit board,

The present invention relates to an apparatus for inspecting an insulation state between circuit patterns of a printed circuit board and a method for inspecting the insulation.

The present application claims priority based on Japanese Patent Application No. 2012-170642 filed on July 31, 2012, the contents of which are incorporated herein by reference.

In the case of inspecting the insulation state between the circuit patterns of the printed circuit board, the inspection voltage is applied to the circuit patterns of the printed circuit board through the inspection probes, and the insulation resistance value is obtained from the inspection voltage and the current flowing through the inspection probe. It is checked whether the insulation state is good or not. In this case, sparking may occur between the circuit patterns due to voltage application. In the case where the spark occurs, the substrate is determined as a defective product.

Patent Literature 1 discloses a technique in which a voltage is applied to a circuit pattern and a voltage between circuit patterns is detected between the start of voltage application and a predetermined timing and the presence or absence of a voltage drop between circuit patterns generated by the spark is detected , And when the voltage drop is detected, it is determined that the substrate is determined to be defective.

More specifically, in Fig. 2 of Patent Document 1, the elapsed time from the time when the test voltage is applied between the circuit patterns is counted, and the insulation resistance value is calculated at a predetermined time when the voltage of the circuit pattern becomes the normal state , It is determined whether or not a spark has occurred between the circuit patterns until that time. When it is determined that no spark has occurred, the measured resistance value is compared with the threshold value to determine whether the insulation state between the circuit patterns is defective or not Method is shown. Further, in Fig. 3 of Patent Document 1, it is first determined whether a spark occurs after voltage application, and when a spark occurs, the substrate is determined to be a defective product. On the other hand, A method of calculating a resistance value by measuring an overcurrent and determining a defectiveness based on the resistance value is shown.

Japanese Patent No. 3546046

However, it is difficult to set the timing for detecting the presence or absence of spark generation. In the former method of detecting the presence or absence of spark while calculating the insulation resistance value, sparking may occur even after the voltage becomes a normal state. There has been a problem that it is impossible to determine a defective product when a spark occurs after calculating the insulation resistance value. Even in the latter method in which the presence or absence of spark occurrence is first detected and then the insulation resistance value is calculated, a blank time is generated between the determination of the presence / absence of spark generation and the calculation of the insulation resistance value, .

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and an object of the present invention is to improve the accuracy of insulation inspection of a printed board by surely detecting the occurrence of sparks.

The insulation inspection apparatus of a printed board of the present invention is a device for inspecting insulation of a printed circuit board by applying a direct current voltage between circuit patterns of a printed circuit board and detecting an insulation state between the circuit patterns based on an applied voltage value and an insulation resistance value calculated from a current value flowing between the circuit patterns And a voltage detection unit for detecting a voltage of the spark from a current detection start time after voltage application is started to a time when a predetermined time elapses from the completion of voltage rise as a start point, A current increase detector for detecting whether a current value flowing between the circuit patterns due to a spark generated between the circuit patterns increases within a detection time by a predetermined threshold value or more; When an increase is detected, , And a spark detection time setting unit capable of setting the prescribed time.

According to another aspect of the present invention, there is provided a method of inspecting an insulated printed circuit board, comprising the steps of: applying a DC voltage between circuit patterns of a printed circuit board; A method for inspecting a printed circuit board that determines whether or not an insulation state is defective, comprising: setting a spark detection time from a current detection start time after voltage application start to a time when a specified time elapses, And when it is detected within the spark detection time that the value of the current flowing between the circuit patterns has increased by a predetermined threshold or more, the printed board is determined to be defective.

By setting the end of the spark detection time after the elapse of the specified time from the completion of the voltage rise, it is possible to reliably detect not only the voltage rise but also the spark occurrence in the subsequent voltage stabilization. Since the predetermined time from the time when the voltage rise is completed can be set with respect to the spark detection time, the generation of the spark can be appropriately detected by setting the time according to the production lot of the printed board.

In the insulation inspection apparatus of the present invention, the applied voltage control section may control the applied voltage to any one of an insulation resistance detection voltage for obtaining the insulation resistance value or a spark detection voltage higher than the insulation resistance detection voltage And the insulation state judging section for judging whether or not the insulation state is defective determines the insulation resistance value between the circuit patterns by the insulation resistance detection voltage applied after the lapse of the spark detection time to judge whether or not the insulation state is defective And the current increase detecting section may detect a current increase due to the spark detection voltage applied within the spark detection time.

In the insulation inspection method of the present invention, the applied voltage may be controlled by any one of an insulation resistance detection voltage for obtaining the insulation resistance value or a spark detection voltage higher than the insulation resistance detection voltage, It may be determined that the printed board is defective when it is detected that the current value due to the spark detection voltage has increased by a predetermined threshold value or more.

According to this embodiment, by dividing and controlling the voltage for spark detection and the voltage for insulation resistance calculation, it is possible to set the optimum voltage according to each inspection, and by setting the spark detection voltage to a high voltage, Can be detected.

In the insulation inspection apparatus for a printed board of the present invention, the applied voltage control section may further include a voltage rise time setting section for setting a time from the start of voltage application to the completion of voltage rise.

According to this embodiment, when an applied voltage is instantaneously applied, sparking occurs momentarily and it is difficult to detect. Even in such a situation, the voltage rise time can be changed so that the occurrence of spark can be surely detected, Defective products can be determined.

In the insulation inspection apparatus for a printed board of the present invention, the current increase detecting section may also detect a time required for increasing a current equal to or larger than the predetermined threshold value, and the spark determiner determines, It may be determined that the printed board is defective when it is detected that the time required for the current increase is within the range of the predetermined current increase determination time when a current increase exceeding the threshold value is detected.

In the insulation inspection method of the present invention, when it is detected that the current value flowing between the circuit patterns increases by a predetermined threshold or more, a necessary time is detected until the current value increases by a predetermined threshold or more, It may be determined that the printed board is defective when it is detected that the time is within the range of the predetermined current increase determination time.

In this case, the spark determiner may further include a current increase determination time setting unit that can change the current increase determination time.

In the insulation inspection method of the present invention, the time from the start of voltage application to the completion of voltage rise may be set in advance.

In this embodiment, when it is detected that the time required for the current increase is within the predetermined time range in addition to the detection of the current increase, it is determined that the printed board is defective, so that an erroneous determination due to noise can be prevented, Can be performed.

In the insulation inspection method for a printed circuit board according to the present invention, detection of a current flowing between the circuit patterns may be started after a predetermined time has elapsed since the start of voltage application.

That is, since an unstable state of the electric signal occurs immediately after the start of the voltage application, in this embodiment, the current detection is started avoiding the time for preventing erroneous determination.

According to the present invention, it is possible to reliably detect spark occurrence not only at the time of voltage rise but also at the time of voltage stabilization thereafter, and at the same time, by setting the spark detection time in accordance with the production lot of the printed circuit board, So that the inspection precision can be improved.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a block diagram showing an insulation inspection apparatus for a printed board according to a first embodiment of the present invention. FIG.
2 is an electric characteristic diagram showing a temporal change in voltage between a voltage in the case where a spark occurs and an electric current flowing between the circuit patterns in an embodiment of the present invention.
3 is an electric characteristic diagram showing a temporal change in voltage between a case where a spark occurs and an electric current flowing between circuit patterns in the embodiment of the present invention.
4 is a flowchart showing a method for inspecting insulation of a printed circuit board according to the first embodiment of the present invention.
5 is a block diagram showing an insulation inspection apparatus for a printed board according to a second embodiment of the present invention.
6 is a flowchart showing a method for inspecting insulation of a printed circuit board according to a second embodiment of the present invention.
7 is a block diagram showing an insulation inspection apparatus for a printed board according to a third embodiment of the present invention.
8 is a flowchart showing a method for inspecting insulation of a printed circuit board according to the third embodiment of the present invention.
9 is a flowchart showing a method for inspecting insulation of a printed circuit board according to a fourth embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Referring to Fig. 1, the insulation inspection apparatus for a printed circuit board in the first embodiment performs insulation inspection for a combination of a plurality of circuit patterns C1 to C4 on a printed board 1. Fig. This insulation inspecting apparatus comprises a switch circuit 2 having a plurality of changeover switches A0 to A4 and B0 to B4 connected to respective circuit patterns C1 to C4, A variable voltage source 4 for applying a voltage to the circuit patterns C1 to C4 via the switch circuit 2 and an applied voltage control unit 5 for controlling the opening and closing of the circuit patterns C1 to C4, A voltage detecting section 6 and a current detecting section 7 for detecting a voltage and a current between circuit patterns connected to the variable voltage source 4 by the switch circuit 2, A rise completion detector 8, a current increase detector 9 for detecting whether the current value has increased by a predetermined threshold value or more, a spark detection time setting unit 10 for setting a spark detection time as described later, (11) and a display device (12).

The switch circuit 2 has a + side main changeover switch A0 connected to the + side of the variable voltage source 4 and a - side main changeover switch B0 connected to the - side. To the positive side main changeover switch A0, the + side changeover switches A1 to A4 connected to the circuit patterns C1 to C4 are connected in parallel. - Side-side changeover switches B 1 to B 4 connected to the respective circuit patterns C 1 to C 4 are connected in parallel to the main-side changeover switch B 0.

As shown in Table 1, the switch control section 3 switches the ON / OFF states of the respective changeover switches A0 to A4 and B0 to B4 / OFF) is controlled. The blank in Table 1 indicates the OFF state.

As shown in Table 1, first, in the first inspection, the + side changeover switches A1 and A2 of the circuit pattern C1 and the circuit pattern C2 are put in the connected state (ON) And the minus side changeover switches B3 and B4 of the pattern C3 and the circuit pattern C4 are connected (ON). At this time, all the main changeover switches A0 and B0 are set to the open state (OFF). Then, the voltage is applied to each of the circuit patterns C1 to C4 by changing the connection state (ON) in the order of the-side main changeover switch B0 to the + side main changeover switch A0. In the first inspection, the circuit pattern C1 and the circuit pattern C3, the circuit pattern C1 and the circuit pattern C4, the circuit pattern C2 and the circuit pattern C3, And the insulation state between the pattern C2 and the circuit pattern C4 is respectively inspected.

Subsequently, in the second inspection, the + side changeover switch A1 of the circuit pattern C1 becomes the connected state (ON) and the minus side changeover switch B2 of the circuit pattern C2 is in the connected state (ON) , The insulating state between the circuit pattern C1 and the circuit pattern C2 is inspected when the both main changeover switches A0 and B0 are sequentially turned ON from the minus side.

In the third inspection, the + side changeover switch A3 of the circuit pattern C3 becomes the connected state (ON) and the -side changeover switch B4 of the circuit pattern C4 becomes the connected state (ON) The state of insulation between the circuit pattern C3 and the circuit pattern C4 is checked if the both main changeover switches A0 and B0 are turned on in order from the minus side.

By the operation of each of the above-described changeover switches, the insulation state by all the combinations of the four circuit patterns C1 to C4 is inspected.

The applied voltage control unit 5 controls the applied voltage by the variable voltage source 4 and has a function of changing the applied voltage by the operator.

The voltage detecting section 6 and the current detecting section 7 are provided with an A / D converter for converting an analog detection signal from the voltmeter 13 or the ammeter 14 into a digital signal. Based on the detection signal, Current is detected.

The voltage rise completion detector 8 samples the voltage signal outputted from the voltage detector 6 at a predetermined cycle and when the sampled voltage signal reaches the prescribed voltage set by the applied voltage controller 5, And outputs the rising completion signal.

The current increase detecting section 9 samples the current signal outputted from the current detecting section 7 at a predetermined cycle and compares the previous current signal with the current current signal and outputs a current increase signal when the current value increases by a predetermined threshold value or more Output.

The main control unit 11 is provided with a CPU 21, a memory 22 and a data communication unit 23 for data communication with each unit. A spark judgment section 25 for judging whether a spark has occurred within a spark detection time, and an insulation state judgment section 26 for judging an insulation state in insulation inspection performed after spark detection.

The spark detection time setting unit 10 sets the specified time after the voltage rise completion detecting unit 8 detects the completion of the voltage rise and has a function of allowing the operator to change the specified time. The spark detection time is the time from the completion of the voltage rise to the end of the specified time after the start of the voltage application and the start of the voltage rise after the start of the voltage application, An increase in current is detected.

The spark detection time will be described with reference to Figs. 2 and 3. The spark between the circuit patterns occurs when the applied voltage rises as shown in Fig. 2 and when the applied voltage rises Occurs after completion.

In Fig. 2 and Fig. 3, the time t0 is at the start of the voltage application, and the current detection is started from the time t1 after the lapse of the predetermined time from the time t0. The time from the time t0 to the time t1 is an unstable period of the electric signal immediately after the voltage application. In order to prevent erroneous judgment, the current is detected after the elapse of this time. In Fig. 2, a spark occurs during the voltage rise, so that a voltage drop occurs and the current value instantaneously increases.

In Fig. 2 and Fig. 3, the time t2 indicates the completion of the voltage rise. In Fig. 3, a spark occurs after the time t2, and a voltage drop and an instantaneous increase in the current value occur. The time t3 indicates the end of the current increase detection, and the time from the time t2 at the completion of the voltage rise to the time t3 is the prescribed time described above. The time from the time t1 to the time t3 is the time for detecting the current increase, that is, the spark detection time. The above-described spark detection time setting unit 10 sets the specified time from the time when the voltage rise is completed to the time t3. The time t3 can be set only after the time t2 when the voltage rise is completed, It is locked so that the time can not be set.

2 and 3, the current increase detecting section 9 compares the previous current signal I1 sampled at a predetermined cycle with the current current signal I2, and if the difference (I2-I1) And outputs a current increase signal when it exceeds the threshold value.

The spark judging unit 25 judges that a spark occurs when a current increase signal is output from the current increase detecting unit 9 within the spark detection time.

The insulation state determination section 26 calculates an insulation resistance value based on the detection signal from the voltage detection section 6 and the current detection section 7 and determines that the insulation insulation value is equal to or smaller than a predetermined determination resistance value .

Next, a first embodiment of a method for inspecting the printed board 1 with the insulation inspection apparatus constructed as described above will be described with reference to the flowchart of Fig.

First, the voltage to be applied is set by the applied voltage control unit 5, and the spark detection time is set by the spark detection time setting unit 10 (actually, the specified time from the voltage rising completion time t2 to the time t3) (Step S1).

Subsequently, at least one of the + side changeover switches A1 to A4 is turned ON according to Table 1 (step S2), and at least one of the - side changeover switches B1 to B4 is turned ON (step S3).

Then, the + side main changeover switch A0 is turned on (step S5) after turning the side main changeover switch B0 to ON (step S4). Thereafter, a predetermined time (t1-t0) has elapsed (step S6), and the current detection unit 7 starts current detection (step S7).

It is judged whether or not the current signal outputted from the current detecting section 7 is sampled at a predetermined cycle and the previous current signal and the current current signal are compared in the current increase detecting section 9 and the result that the current value increases by a predetermined threshold value or more (Step S8). If it is determined in step S8 that a current increase of a predetermined threshold value or more can not be detected (NO), it is determined whether or not the specified time has elapsed from the completion of the voltage rise (i.e., whether or not the spark detection time has elapsed) Step S9). Whether or not the specified time has elapsed from the completion of the voltage rise is determined by whether or not the specified time set by the spark detection time setting unit 10 has elapsed since the rise completion signal was output in the voltage rise completion detector 8 . If it is determined that the specified time has not elapsed (NO in step S9), the process returns to step S8 and continues to detect whether or not the current exceeding the predetermined threshold value has increased until the specified time has elapsed. If it is determined in step S8 that the current increase signal exceeding the predetermined threshold value is detected by the current increase signal from the current increase detection section 9 (in the case of "YES "), It is determined that the substrate is a defective product (step S10).

If it is determined in step S9 that the predetermined time has elapsed from the completion of the voltage rise (in the case of "YES"), the voltage detecting section 6 and the current detecting section 7 detect the current i flowing between the voltage V and the circuit pattern S11). Then, the resistance value R between the circuit patterns is calculated from the voltages V and the current i by the insulation state judging section 26 (step S12). The calculated resistance value R is compared with the predetermined judgment resistance value Rj, It is determined whether or not a resistance value R is equal to or higher than the judgment resistance value Rj (step S13). When it is not judged that the calculated resistance value R is equal to or larger than the judgment resistance value Rj (in the case of "NO" in the step S13), the combination of the circuit patterns is stored as an insulation failure point (step S14) A0 to A4, B0 to B4) are turned OFF (step S15). If it is determined in step S13 that the resistance value R is equal to or larger than the determination resistance value Rj (in the case of "YES "), the isolation state between the circuit patterns is good.

After all the changeover switches A0 to A4 and B0 to B4 are turned off in step S15, it is judged whether or not the inspection for all the combinations of circuit patterns is completed (step S16) No "), the process proceeds to step S2, and the same inspection as the above is performed with respect to the combination of the following circuit patterns in accordance with Table 1. [

If it is determined in step S16 that the inspection for all the combinations of circuit patterns has been completed (in the case of "YES "), it is determined whether or not there is a stored insulation failure point (step S17). If it is determined that there is a defective insulation point ("YES"), it is determined that the substrate is defective (step S18). If it is determined that there is a defective insulation point (Step S19).

Finally, the entire changeover switches A0 to A4 and B0 to B4 are turned OFF (step S20), and the inspection process is terminated.

In the above-described series of insulation inspection methods, the spark detection time of the step S1 (actually, the specified time from the voltage rising completion time t2 to the time t3) is appropriately determined depending on the type of the printed board 1 to be inspected, Respectively. In this case, as described above, the specified time elapsed time t3 from the completion of the voltage rise can be set only in the time zone after the voltage rising completion time t2, and can not be set in the time zone before the time t2. Therefore, the spark detection time includes the time zone before the time t2, and it is possible to detect the spark occurrence at the time of the voltage rise shown in Fig. 2, and also to ensure the spark occurrence at the time of the voltage stabilization shown in Fig. 3 Can be detected.

It is also possible to detect the occurrence of spark by detecting a current increase not less than a predetermined threshold value instead of a voltage drop as in the invention described in Patent Document 1, And the current detection is started after the elapse of the time (t1-t0). Therefore, it is possible to detect the occurrence of sparks without being affected by the unstable state of the current immediately after the voltage application.

In the case of detecting the occurrence of sparks due to the voltage drop as in the invention described in Patent Document 1, depending on the power supply performance to supply the applied voltage, for example, in the case of a constant voltage power source, There is a possibility that the voltage drop can not be detected and the spark generation can not be reliably detected. Further, when a voltage is detected from the start of voltage application, if a state in which an electric signal becomes unstable immediately after voltage application occurs, the voltage drop is erroneously detected as a voltage drop, which may result in an erroneous determination.

In this embodiment, the increase in current is detected from the time t1 shown in Fig. 2 and Fig. 3 by avoiding the unstable period immediately after the voltage application. Therefore, the occurrence of spark can be reliably detected without generating the erroneous determination.

5 and 6 show block diagrams and flowcharts of a second embodiment of the present invention in which the time until completion of the voltage rise can be set to an arbitrary time with respect to the applied voltage. A voltage rise time setting unit 31 is provided in the applied voltage control unit 5 so that the time from the start of voltage application to the completion of voltage rise can be set. The other constituent elements are the same as those in the embodiment of Fig. 1, so that the same reference numerals as in Fig. 1 are attached to Fig. 5 and the description is omitted. In FIG. 6, the same processes as those in the flowchart of FIG. 4 are denoted by the same reference numerals and the description thereof is simplified (the same applies to FIG. 7 and later).

First, an applied voltage is first set to 0 V, a spark detection time is set, and a target voltage rise time is set (step S25). Then, after executing the processes from step S2 to step S5 similar to the first embodiment shown in Fig. 4, the voltage rise value per unit time is calculated from the voltage value and the voltage rise time (step S26) The voltage rise by the voltage rising value is started (step S27). Then, after executing the processes from step S6 to step S8 similar to the first embodiment, it is determined whether or not the set voltage rise time has elapsed by the rise completion signal from the voltage rise completion detector 8 Step S28). If it is determined that the voltage rising time has elapsed ("YES"), the voltage rising is stopped (step S29) and the process of step S9 is executed. If it is determined in step S28 that the voltage rising time has not elapsed (NO), the process proceeds to step S9, and thereafter, a process similar to that of the first embodiment is performed.

In this second embodiment, the time from the start of the applied voltage to the completion of the voltage rise can be arbitrarily set, so that even if the instantaneous application of the applied voltage causes sparking to occur instantaneously and detection is difficult, , It is possible to reliably detect the occurrence of spark and accurately determine the defective product of the substrate.

7 and 8 show a flow chart of a third embodiment of the present invention. In the spark generation detection, not only the current increase not less than the predetermined threshold value but also the current consumption increase time Is an embodiment with a requirement. The detection function of the time required for the current increase is provided in the current increase detection section 9. [ The spark judgment section 25 is provided with the function of setting the judgment time with respect to the current increase and comparing the judgment time with the time required for the actual current increase. The spark determination unit 25 is provided with a current increase determination time setting unit 32 that can change the determination time at an appropriate time according to a lot of the printed board or the like. When the current increase time is within the range of the current increase determination time, the spark determination section 25 determines that the current increase time is within the range of the current increase determination time, Is determined to have occurred. Other components are the same as those in the embodiment of Fig.

In this third embodiment, the applied voltage is first set, the spark detection time is set, and the determination time for the current increase is set (step S31). After executing the processing from step S2 to step S5 similar to the first embodiment shown in Fig. 4, the current signal outputted from the current detecting section 7 is sampled at a predetermined cycle in step S8, Is greater than or equal to the threshold value of " 1 " If it is determined that the current increase has been detected ("YES"), it is determined whether or not the time required for the current increase is within the range of the current increase determination time (step S32). If it is determined that the time required for the current increase is within the range of the determination time (in the case of "YES"), it is determined that the spark generation is detected and the printed board is determined to be defective (step S10).

If it is determined in step S32 that the time required for the current increase is within the range of the determination time (in the case of "NO"), the process proceeds to step S9, and then the same process as in the first embodiment shown in FIG. 4 is performed.

When it is detected that the time required for the current increase is within the range of the predetermined determination time in addition to the detection of the current increase as described above, it is determined that the printed board is defective, so that the erroneous determination due to the noise can be prevented, .

Fig. 9 shows a flow chart of the fourth embodiment of the present invention, in which the applied voltage for spark detection and the applied voltage for calculating the insulation resistance are set to different values.

In this embodiment, the applied voltage control section 5 sets the voltage applied between the circuit patterns to one of the spark detection voltage for detecting the occurrence of spark and the insulation resistance detection voltage for calculating the insulation resistance. The spark detection voltage is set to be higher than the insulation resistance detection voltage. For example, the spark detection voltage is set to 200V and the insulation resistance detection voltage is set to 100V.

First, the applied voltage is set to the spark detection voltage Vs and the spark detection time is set (step S35). By executing the processing from step S2 to step S9 similar to those in the first embodiment of Fig. 4, it is determined whether or not a spark has occurred based on the current increase signal between the completion of the voltage rise and the elapse of the specified time (Steps S8 and S9). Thereafter, the entire changeover switch is turned OFF (step S36), and it is judged whether or not the spark detection inspection is completed for all combinations of circuit patterns (step S37). If it is not judged that all the inspections have been completed (in the case of "No"), the process from step S2 is repeated in the order of Table 1.

If it is determined in step S37 that all the tests (spark detection tests) have ended (in the case of "YES"), the applied voltage is set to the insulation resistance detection voltage Vi (step S38) Is inspected.

Side main changeover switch B0 is turned ON (step S39) and the + side main changeover switch A0 is turned ON (step S40), and the + side changeover switches A1 to A4 (Step S41), and turns on at least one of the - side changeover switches B1 to B4 (step S42). Then, a process for calculating the resistance value R from the voltage V and the current i after step S11, which is the same as that of the first embodiment of Fig. 4, is performed to determine whether or not the insulation state is defective.

In this fourth embodiment, since the spark detection voltage is divided into the insulation resistance detection voltage, the optimum voltage can be set according to each inspection. Further, by setting the spark detection voltage higher than the insulation resistance detection voltage, spark generation can be detected more reliably.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications can be made without departing from the gist of the present invention.

For example, in each of the embodiments, the resistance value R is compared with the determination resistance value Rj in step S13. If it is determined that the calculated resistance value R is not equal to or greater than the determination resistance value Rj (NO) And after the completion of all the inspection, it was judged that there was a defective insulation part that was stored. However, when the result of the determination in step S13 is "NO ", it may be determined that the process is not completed until all the tests are completed and that the product is defective.

The current increase detecting section 9 may be configured to change the sampling interval of the current signal from the current detecting section 7. Thereby, it is possible to surely detect the occurrence of spark by setting the detection interval in accordance with the noise state, and to perform the defective product determination more accurately.

The time from the voltage application start time t0 to the current detection start time t1 may be appropriately changed. Thus, even when the instability time of the electric signal immediately after the start of voltage application changes, the occurrence of spark can be surely detected, and the defective product of the substrate can be accurately determined.

1: printed board
2: Switch circuit
3: Switch switching control section
4: variable voltage source
5: Applied voltage control section
6: Voltage detector
7:
8: Voltage rise completion detector
9: current increase detector
10: Spark detection time setting unit
11: Control device
12: Display device
13: Voltmeter
14: Amperemeter
21: CPU
22: Memory
23: Data communication section
24: Spark detection time setting unit
25: spark judgment section
26:
31: Voltage rise time setting unit
32: current increase determination time setting unit
A0: + side main changeover switch
A1 to A4: + side switch
B0: - side main changeover switch
B1 to B4: - side switch
C1 to C4: Circuit pattern

Claims (10)

A method for inspecting insulation of a printed circuit board which applies a direct current voltage between circuit patterns of a printed circuit board and judges whether or not the insulation state between the circuit patterns is defective based on an applied voltage value and an insulation resistance value calculated from a current value flowing between the circuit patterns And a spark detection circuit for detecting a spark generated between the circuit patterns within a spark detection time from a current detection start time after the start of voltage application to a time when a specified time has elapsed from the completion of the voltage rise, A current increase detector for detecting whether a current flowing between the circuit patterns increases by a predetermined threshold value or not; A spark judgment section for judging a defective product, Insulation testing device for printed circuit board, characterized by having a setting unit for setting a time as possible spark detection time. The apparatus according to claim 1, wherein the applied voltage control unit controls the applied voltage to any one of an insulation resistance detection voltage for obtaining the insulation resistance value or a spark detection voltage higher than the insulation resistance detection voltage, Wherein the insulation state judging section for judging whether or not the insulation state is defective determines whether the insulation state is defective by calculating the insulation resistance value between the circuit patterns based on the insulation resistance detection voltage applied after the spark detection time elapses, Detects an increase in current due to the spark detection voltage applied within the spark detection time. The insulation inspection apparatus for a printed board according to any one of claims 1 to 3, wherein the applied voltage control unit further comprises a voltage rise time setting unit for setting a time from the start of voltage application to the completion of voltage rise. The spark determination circuit according to claim 1 or 2, wherein the current increase detection unit further detects a time required for increasing a current equal to or larger than the predetermined threshold value, and the spark determination unit Wherein when the current increase is detected, it is determined that the printed board is defective when it is detected that the time required for the current increase is within the range of the predetermined current increase determination time. 5. The insulation inspection apparatus for a printed board according to claim 4, wherein the spark determiner further comprises a current increase determination time setting unit that changes the current increase determination time. A method for inspecting insulation of a printed circuit board which applies a direct current voltage between circuit patterns of a printed circuit board and judges whether or not the insulation state between the circuit patterns is defective based on an applied voltage value and an insulation resistance value calculated from a current value flowing between the circuit patterns A step of setting a spark detection time from a current detection start time after the start of voltage application to a time when a specified time elapses from the time of completion of voltage rise in advance; And a step of determining that the printed board is defective when it is detected that the current value flowing between the circuit patterns increases by the predetermined threshold value or more Insulation inspection method of printed board. 7. The spark plug according to claim 6, wherein the applied voltage is controlled to any one of an insulation resistance detection voltage for obtaining the insulation resistance value or a spark detection voltage higher than the insulation resistance detection voltage, Is judged to be a defective product when it is detected that the current value of the printed board has increased by the predetermined threshold value or more. The inspecting method of a printed board according to claim 6 or 7, wherein a time from the start of voltage application to the completion of voltage rise is set in advance. The method according to claim 6 or 7, wherein when it is detected that the value of the current flowing between the circuit patterns has increased by the predetermined threshold value or more, it is necessary until the current value flowing between the circuit patterns increases by the predetermined threshold value or more Further comprising a step of detecting a time, and when it is detected that the time is within a range of a predetermined current increase determination time, the printed board is determined to be a defective product. The inspecting method of a printed board according to claim 9, wherein the current increase determination time can be changed.

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