JP4875891B2 - Withstand voltage test equipment - Google Patents

Description

  The present invention relates to a withstand voltage test apparatus, and more particularly, to a withstand voltage test apparatus that facilitates the analysis of defective products when a failure determination is made.

  As a parameter for evaluating the safety and reliability of an electric / electronic device, firstly, electrical insulation can be mentioned. Insulation is an important element for preventing accidents. Therefore, the test method is defined by various safety standards such as the IEC standard, the UL standard, and the Electrical Appliance and Material Safety Law.

  The test voltage and test time are determined for each product. Basically, a predetermined test voltage (generally an AC voltage) is applied between the electrode terminals of the product (device under test) from the voltage generator. Then, the test current (leakage current) Ia flowing through the device under test is measured and compared with a preset threshold value Ib. If Ia <Ib (or Ia ≦ Ib), a PASS (pass) determination is made. If Ia ≧ Ib (or Ia> Ib), it is determined as FAIL (failure).

  FIG. 5 shows a flowchart of a withstand voltage test that has been generally performed. First, the test is started after the user sets the “test voltage” to be applied to the DUT, the “test current threshold” and the “test time”, which are pass / fail criteria. During this test, the measurement unit measures the test current Ia flowing through the device under test, and determines the magnitude relationship between the test current Ia and the test current threshold Ib.

As a result, if Ia <Ib, the test is continued until the test time elapses, and a PASS determination is issued after the test time elapses. On the other hand, if Ia ≧ Ib, the test is stopped at that point without waiting for the elapse of the test time and a FAIL judgment is issued.
JP 2003-28915 A

  When setting the threshold value Ib of the test current, it is usually set lower than the current value that leads to dielectric breakdown for safety. As an example, assuming that the current value leading to dielectric breakdown is 40 mA, and the test current threshold Ib is set to 20 mA, in the conventional example, the test current Ia slightly exceeds this (for example, 20.1 mA). However, the test is stopped and a FAIL judgment is issued.

  If only PASS or FAIL is selected, there is no problem in stopping the test even when the test current Ia slightly exceeds the threshold value Ib as described above. It is not possible to know whether the test current Ia of the current flowed and a FAIL judgment was made.

  That is, since it cannot be determined whether the FAIL judgment is made slightly exceeding the threshold value Ib or the test current Ia that greatly exceeds the threshold value Ib flows, the FAIL judgment is made. It is necessary to reset the Ib and perform the test again.

  In order to solve this problem, the test current value at that time may be displayed at the time of FAIL judgment. However, since the average value is normally used to display the test current value, if the test is stopped at that time at the time of FAIL judgment, the average value calculation will not be in time, so it is not possible to display the test current value at the time of FAIL judgment. Can not.

  Therefore, an object of the present invention is to make it easy to analyze how much test current has flowed to determine FAIL when a FAIL determination is made in a withstand voltage test.

In order to solve the above problems, the invention according to claim 1 is a voltage generator that applies a predetermined test voltage to the device under test, and a test current that flows through the device under test when the test voltage is applied. A measurement unit, a control unit, a test condition input unit that sets at least a test voltage value, a test time, and a test current threshold value as a pass / fail criterion in the control unit, and a display unit that displays a test result, The voltage generator is controlled by the controller based on each test condition set from the test condition input unit, and the withstand voltage characteristics of the device under test are determined by the value of the test current measured by the measuring unit. In the withstand voltage test device to be inspected, a test stop current value larger than the test current threshold can be set separately from the test current threshold to the control unit from the test condition input unit, and the control unit Is During after start of the test of the test time set from the test condition input unit, monitors the test currents measured at the measuring section, when the upper Symbol test current is smaller than the threshold value of the test current , after the test time, performing a first routine for outputting the acceptance on the display section, when the upper Symbol test current is greater than the stop test current value, without waiting for the elapse of the test time, the test current has stopped the test when it is determined to be greater than the stop test current running second routine for outputting a fail judgment on the display unit, the upper Symbol test current of the test current threshold And when the test stop current value is smaller than the test stop current value, the test is continued until the test time ends, and a third routine for outputting a failure determination to the display unit is executed. Yes.

  According to a second aspect of the present invention, in the first aspect, in the case of the second routine, the control unit outputs a display indicating that the test is stopped before the test time has elapsed in the second routine. In the case of the third routine, a display indicating that the test has been continued until the test time is output to the display unit.

  The invention according to claim 3 is executed in the first or second aspect, wherein the control unit is executed when the test current is larger than a threshold value of the test current and smaller than the test stop current value. In the third routine, even when the test current becomes smaller than the test current threshold at the end of the test time, a failure determination is output to the display unit.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the control unit includes a pass determination period in which the test current is smaller than a threshold of the test current during the test time; If the test current is larger than the test current threshold and includes both failure determination periods smaller than the test stop current value, the test is continued until the test time is over and the display is continued. A non-assertive failure determination is output to the part.

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the control unit sets the test stop current value at a predetermined rate in conjunction with a threshold value of the test current. It is a feature.

  According to the first aspect of the present invention, the threshold value of the test current that is a pass / fail judgment criterion and a test stop current value larger than that are set, and the test current flowing through the device under test is larger than the test current threshold value. When the test current is larger than the test stop current value, the test is stopped at that time, whereas the test current is larger than the test current threshold, and If the test stop current value is smaller than the test stop current value, the test is continued until the test time is finished. Therefore, whether the test current at the time of FAIL judgment is smaller than the test stop current value or less than the test stop current value. It is possible to distinguish whether it is large or not, and it becomes easy to analyze a defective product.

  According to the second aspect of the present invention, in the case of the second routine, a display indicating that the test is stopped before the lapse of the test time is output on the display unit, and in the case of the third routine, the display is displayed. Since the display indicating that the test was continued until the test time is output to the part, for example, even if the user is not completely attached to the test device, the test current at the time of FAIL judgment is Whether it is smaller than the value or larger than the test stop current value can be immediately recognized.

  According to the third aspect of the present invention, in the third routine executed when the test current is larger than the test current threshold and smaller than the test stop current value, the test current is reached at the end of the test time. Even if the test current becomes smaller than the threshold of the test current, the failure judgment is output to the display unit, so that the failure judgment can be made without overlooking the DUT that once showed a breakdown voltage failure. A high withstand voltage test can be performed.

  According to the invention described in claim 4, during the test time, the pass determination period in which the test current is smaller than the test current threshold, the test current is larger than the test current threshold, and the test stop current value is smaller than the test stop current value. If both of the small failure determination periods are included, the test is continued until the test time ends, and the non-deterministic failure determination is output on the display unit. As one of the causes of the breakdown voltage failure, it is possible to suggest a review of test conditions and operation methods.

  Further, according to the invention described in claim 5, since the test stop current value is set in conjunction with the test current threshold at a predetermined rate, it is possible to save the trouble of setting the test stop current value for each test. Can do.

  Next, some embodiments of the present invention will be described with reference to FIGS. 1 to 4, but the present invention is not limited thereto. FIG. 1 is a schematic block diagram illustrating an example of a withstand voltage test apparatus according to the present invention, FIG. 2 is an operation flowchart according to the first embodiment of the present invention, and FIGS. 3 and 4 are second and third embodiments of the present invention. It is an operation | movement flowchart which concerns on 3rd Embodiment.

  As shown in FIG. 1, the withstand voltage test apparatus includes a voltage generator 11 that applies a predetermined test voltage to the device under test EUT, and a test current Ia that flows through the device under test EUT when the test voltage is applied. Measuring unit 12 for measuring, control unit 13, input unit 14 for giving test conditions to control unit 13, display unit 15 for displaying test results, and output for transmitting test results to an external device such as a personal computer (not shown) Part 16.

  The device under test EUT may be an electric / electronic device, an electronic component, an electronic material, or the like, and a test voltage is applied from the voltage generator 11 between a pair of electrode terminals (not shown). In the withstand voltage test apparatus, an AC power supply is generally used for the voltage generator 11, but a DC power supply may be used in some cases. The test voltage is determined for each EUT.

  The measurement unit 12 can be configured by a current detection resistor through which the test current Ia of the EUT to be tested flows and a voltmeter (both not shown) that measures a voltage drop generated in the current detection resistor. For the control unit 13, a CPU (Central Processing Unit), a microcomputer, or the like may be used.

  Various test conditions are set in the control unit 13 from the input unit 14. According to the present invention, the test conditions include the test voltage, the test time, and the test current threshold value Ib that serves as a pass / fail criterion. The test stop current value Ic is included. An operation panel such as a keyboard may be used for the input unit 14.

  The test stop current value Ic is a value larger than the test current threshold value Ib, and preferably a current value at which it is determined that the EUT will obviously cause dielectric breakdown. The test stop current value Ic may be set for each EUT to be tested. However, the test stop current value Ic is linked to the test current threshold value Ib at a predetermined rate, for example, a 50% increase in the test current threshold value Ib. You can also set it.

  The control unit 13 determines the magnitude relationship between the test current Ia input from the measurement unit 12 and the test current threshold Ib and the magnitude relationship between the test current Ia and the test stop current value Ic. That is, if Ia <Ib, a PASS (pass) determination is made, and if Ib ≦ Ia ≦ Ic, a FAIL (failure) determination is made. In this case, the test continues until the end of the test time. If Ia> Ic, the FAIL judgment is made, and at that time, the output of the voltage generator 11 is stopped and the test is stopped.

  In the case of determining the magnitude relationship as described above, the way of attaching the equal sign is not limited to the above example, and as another example, Ia ≦ Ib, Ib <Ia <Ic, Ia ≧ Ic or Ia ≦ Ib, Ib <Ia ≦ Ic, Ia> Ic may be used.

  The display unit 15 is preferably a liquid crystal display panel or a plasma display, but a printer may be used. Any output unit 16 may be employed as long as it can communicate with an external device using a predetermined protocol.

  Next, an operation example of the first embodiment of the present invention will be described with reference to the flowchart of FIG. First, as preparations before the test, a test voltage, a test current threshold value Ib, a test time, and a test stop current value Ic are set in steps ST21 to ST24. Steps ST21 to ST24 are in no particular order. In the withstand voltage test, the test time is usually about 1 minute.

  When the test is started in step ST25, the test current Ia flowing through the device under test EUT is detected (measured) in step ST26, and it is determined whether Ia ≧ Ib in the next step ST27. If the result is NO and Ia <Ib, it is determined whether the test time has elapsed in step ST28. If the test time has not elapsed, the process returns to step ST26, and the test time has elapsed in the state of Ia <Ib In step ST29, a PASS (pass) determination is displayed on the display unit 15, and the test is terminated.

  When Ia ≧ Ib in step ST27, the process proceeds to step ST30 and the display unit 15 performs FAIL determination. In step ST31, it is determined whether Ia ≧ Ic. If the result is YES and Ia ≧ Ic, in step ST32, the display unit 15 displays Ia ≧ Ic together with a FAIL (failure) determination, At that time, the test is terminated (forced stop).

  If the determination result in step ST31 is NO and Ia <Ic, it is determined whether the test time has elapsed in step ST33. If the test time has not elapsed, the process returns to step ST26, and the test time is in the state of Ia <Ic. In step ST34, it is displayed on the display unit 15 that the test time has passed together with the FAIL judgment, and the test is terminated.

  Thus, according to the first embodiment, when the FAIL determination is made, whether or not the test current Ia is smaller than the test stop current value Ic or less than the test stop current value Ic by the display in the steps ST32 and ST34. Therefore, it is not necessary to reset the threshold value Ib and perform the test again as in the conventional example.

  In the above example, it is displayed that Ia ≧ Ic in step ST32. However, it may be displayed that the test is stopped before the test time elapses together with or instead of this. Further, in step ST34, it is displayed that the test time has elapsed, but it may be displayed that Ib <Ia <Ic together with or instead of this.

  Furthermore, only the FAIL judgment may be displayed in steps ST32 and ST34. In this case, the user determines whether the test time is long or short, that is, whether the test end is before the test time elapses or the test time has expired. Therefore, it is determined whether the test current Ia is smaller or larger than the test stop current value Ic.

  Next, an operation example of the second embodiment of the present invention will be described with reference to the flowchart of FIG. Also in the second embodiment, the test voltage, the test current threshold value Ib, the test time, and the test stop current value Ic are set in steps ST21 to ST24, as in the first embodiment. Steps ST21 to ST24 may be out of order. When the test is started in step ST25, the test current Ia flowing through the device under test EUT is detected (measured) in step ST26, and it is determined whether Ia ≧ Ib in the next step ST27.

  If the determination in step ST27 is NO and Ia <Ib, it is determined in step ST28a whether the test time has elapsed, and steps ST26 and ST27 are repeatedly executed until the test time has elapsed. On the other hand, if Ia ≧ Ib in step ST27, in the second embodiment, after setting the FAIL flag in step ST29a, it is determined whether Ia ≧ Ic in step ST30a.

  If the determination in step ST30a is YES and Ia ≧ Ic, in step ST33a, FAIL determination is displayed on the display unit 15 and Ia ≧ Ic is displayed as in the first embodiment, and the test is performed at that time. Is terminated (forced stop).

  If the determination result in step ST30a is NO and Ia <Ic, it is determined in step ST28a whether the test time has elapsed. If the test time has not elapsed, the process returns to step ST26. Then, when the test time has elapsed, it is determined in step ST31a whether the FAIL flag is set.

  If the determination in step ST31a is NO and the FAIL flag is not set, a PASS determination is displayed on the display unit 15 in step ST32a, and the test is terminated. On the other hand, when the determination in step ST31a is YES and the FAIL flag is set, the FAIL determination is made on the display unit 15 in step ST33a. In this case, after the test time has passed, as in the first embodiment. Display that there is, and end the test.

  According to the second embodiment, if the test current Ia is larger than the test current threshold value Ib, the FAIL flag is always set in step ST29a, so that the test current Ia is smaller than the test stop current value Ic. Even if the test current Ia becomes smaller than the test current threshold value Ib for some reason after the elapse of time, the PASS determination is not performed and the FAIL determination is performed, so that the DUT that once showed a breakdown voltage failure is not overlooked. A failure determination can be made, and a highly reliable withstand voltage test can be performed.

  Next, an operation example of the third embodiment of the present invention will be described with reference to the flowchart of FIG. Also in the third embodiment, similarly to the first embodiment, the test voltage, the test current threshold value Ib, the test time, and the test stop current value Ic are set in steps ST21 to ST24. Steps ST21 to ST24 may be out of order. When the test is started in step ST25, the test current Ia flowing through the device under test EUT is detected (measured) in step ST26, and it is determined whether Ia ≧ Ib in the next step ST27.

  When the determination in step ST27 is NO and Ia <Ib, in the third embodiment, after setting the PASS flag in step ST27b, it is determined whether the test time has elapsed in step ST28b, and the test time has elapsed. Steps ST26 and ST27 are repeatedly executed.

  On the other hand, if Ia ≧ Ib in step ST27, in the third embodiment as well, as in the second embodiment, after setting the FAIL flag in step ST29b, it is determined whether Ia ≧ Ic in step ST30b. To do.

  If the determination in step ST30b is YES and Ia ≧ Ic, in step ST34b, along with the FAIL determination, it is displayed that Ia ≧ Ic as in the first embodiment, and the test is performed at that time. Is terminated (forced stop).

  If the determination result in step ST30b is NO and Ia <Ic, it is determined in step ST28b whether the test time has elapsed. If the test time has not elapsed, the process returns to step ST26. When the test time has elapsed, it is determined in step ST31b whether both the PASS flag and the FAIL flag are set.

  If the determination in step ST31b is NO and neither the PASS flag nor the FAIL flag is set, it is determined in the next step ST32b whether only the PASS flag is set. If the result is YES and only the PASS flag is set, a PASS determination is displayed on the display unit 15 in step ST33b, and the test is terminated.

  On the other hand, when the result in step ST32b is NO and the PASS flag is not set, in step ST34b, the FAIL judgment is made on the display unit 15, and in this case, the test time elapses as in the first embodiment. Indicate later and end the test.

  If the determination in step ST31b is YES and both the PASS flag and FAIL flag are set, gray determination is displayed on the display unit 15 in step ST35b, and the test is terminated.

  At the time of this gray determination, the test current Ia is smaller than the test current threshold Ib during the test time, the test current Ia is larger than the test current threshold Ib, and is larger than the test stop current value Ic. It means that both of the small failure judgment periods are included, and it is not possible to specify whether the cause of the failure judgment is in the EUT or the test conditions or operation method. It can be called determination.

  Therefore, this gray determination can suggest to the user a review of the test conditions, the operation method, etc. as one of the causes of the temporary failure of the device under test EUT.

  Note that, after the test is completed, for example, the current value when the FAIL judgment is first made, the maximum value during the test, the current value at the end of the test, and the like can be displayed on the display unit 15. In addition, the withstand voltage test device of the present invention may be commercialized as a single-function device, or may be incorporated as one function of an electric measuring instrument having other measurement functions.

The schematic block diagram which shows an example of the withstand voltage test apparatus by this invention. The flowchart which shows the operation example which concerns on 1st Embodiment of this invention. The flowchart which shows the operation example which concerns on 2nd Embodiment of this invention. The flowchart which shows the operation example which concerns on 3rd Embodiment of this invention. The flowchart which shows the operation example of the conventional withstand voltage test apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Voltage generation part 12 Measurement part 13 Control part 14 Input part 15 Display part 16 Output part

Claims (5)

A voltage generator for applying a predetermined test voltage to the device under test; a measurement unit for measuring a test current flowing through the device under test by applying the test voltage; a control unit; and at least a test voltage for the control unit. A test condition input unit for setting a threshold value of a test current serving as a value, a test time, and a pass / fail judgment criterion, and a display unit for displaying a test result, and the above-mentioned based on each test condition set by the test condition input unit In the withstand voltage test apparatus in which the voltage generating unit is controlled by the control unit, and the withstand voltage characteristic of the device under test is inspected by the value of the test current measured by the measuring unit.
A test stop current value larger than the test current threshold value can be set to the control unit from the test condition input unit separately from the test current threshold value,
The control unit monitors the test current measured by the measurement unit during the test time set from the test condition input unit after the start of the test,
When the upper Symbol test current is smaller than the threshold value of the test current, after the test time, performing a first routine for outputting the acceptance on the display unit,
When the upper Symbol test current is greater than the stop test current value, without waiting for the elapse of the test time, to stop the test at the time when the test current is determined to be greater than the stop test current value A second routine for outputting a failure determination to the display unit is executed,
Upper Symbol test current is greater than the threshold value of the test current, and, when smaller than the stop test current value, to continue the test until the test time is completed to output the fail decision on the display unit A withstand voltage test apparatus that executes a third routine.
  In the case of the second routine, the control unit outputs a display indicating that the test is stopped before the test time has elapsed on the display unit, and in the case of the third routine, the control unit outputs the test time on the display unit. The withstand voltage test apparatus according to claim 1, wherein a display indicating that the test has been continued is output.   In the third routine that is executed when the test current is larger than the test current threshold and smaller than the test stop current value, the control unit performs the test current at the end of the test time. 3. The withstand voltage test apparatus according to claim 1, wherein a failure determination is output to the display unit even when the value becomes smaller than a threshold value of the test current.   The control unit, during the test time, the pass determination period in which the test current is smaller than the test current threshold, the test current is greater than the test current threshold, and is greater than the test stop current value. 4. When both of a small failure determination period are included, the test is continued until the test time ends, and an unconclusive failure determination is output to the display unit. The withstand voltage test apparatus according to any one of the above. 5. The withstand voltage test apparatus according to claim 1, wherein the control unit sets the test stop current value at a predetermined rate in conjunction with a threshold value of the test current. 6.

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