JPH11211778A - Method and apparatus for inspecting migration - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a migration inspecting method providing inspection results suitable for evaluating practical migration resistance of a circuit board. SOLUTION: While applying a DC voltage between two circuit patterns 22a, 22b formed on a circuit board 21 to be inspected, at least one of conducting current, voltage and resistance between both circuit patterns 22a, 22b is measured and generation of migration is detected based on the measurement. In such a method for inspecting migration, at least one measurement is taken while mounting circuit components 14, 15 on the circuit board 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed circuit board,
The present invention relates to a migration inspection method and a migration inspection apparatus suitable for detecting migration in circuit boards such as C packages, hybrid substrates, bare chips, and MCMs (Multi Chip Modules), particularly ion migration that causes dendrites and CAFs. is there.

[0002]

2. Description of the Related Art As shown in FIG. 6, ion migration is a metal deposition phenomenon which occurs when a DC electric field is applied between two circuit patterns 22a and 22b by a DC voltage source 12 on a printed circuit board or the like. is there. That is, when moisture or an electrolyte is present on the surface or inside of the printed circuit board, metal ions are dissolved from the circuit patterns 22a and 22b, and the dissolved metal ions are transferred by a DC electric field, thereby causing a compound such as a metal or an oxide thereof. Is a phenomenon of precipitation. In this case, as a form of precipitation, as shown in FIG.
nductive Anodic Filament). The dendrite is formed by metal ions dissolved from the anode-side circuit pattern 22a reaching the cathode-side circuit pattern 22b, receiving electrons, and depositing on the surface of the printed circuit board. On the other hand, CAF is the circuit pattern 2 on the anode side.
2a melts into the circuit pattern 22
It is formed by depositing in the vicinity of a. As an actual generation order, it takes time for metal ions dissolved from the anode-side circuit pattern 22a to reach the cathode-side circuit pattern 22b as the counter electrode.
F is formed. Next, the metal ions melt out of the CAF, and the melted metal ions reach the circuit pattern 22b to form dendrites. When these dendrites and CAFs are both grown, they cause a short circuit between the circuit patterns 22a and 22b and a decrease in insulation resistance. Therefore, the occurrence of ion migration is a factor that lowers the reliability of electronic devices, particularly, with high-density circuit patterns. For this reason, generally, it is necessary to understand the timing of the occurrence of ion migration by performing an acceleration test under high temperature and high humidity environmental conditions, and to design the reliability of the printed circuit board based on the timing of the occurrence. .

As a device for detecting the occurrence of such ion migration, an inspection device 51 shown in FIG. 4 is conventionally known.

As shown in FIG. 1, an inspection apparatus 51 includes a DC voltage source 12 for applying a constant DC voltage between two circuit patterns 22a and 22b formed on a printed circuit board 21 to be inspected. An ammeter 53 for measuring a current IP flowing between the circuit patterns 22a and 22b and a voltmeter 54 for measuring a voltage VP between the circuit patterns 22a and 22b are provided. 54
Is configured to be able to detect the occurrence of migration based on a change in the measurement value measured by the method.

Next, a method for detecting the occurrence of migration using the inspection apparatus 51 will be described with reference to FIG.

First, in order to accelerate the progress of migration and perform inspection in a short period of time, the printed circuit board 21 before mounting circuit components is placed in a constant temperature and humidity chamber 31 maintained at high temperature and high humidity. Next, the circuit pattern 2 of the printed circuit board 21
After connecting the probes 41a and 41b to the 2a and 22b, the output voltage of the DC voltage source 12 is applied between the circuit patterns 22a and 22b. Next, the current IP is measured by the ammeter 53, and the voltage VP is measured by the voltmeter 54. In this case, as shown in FIG.
P changes at a constant voltage value, while current IP is
As shown in FIG. 6B, the insulation resistance between the circuit patterns 22a and 22b decreases as the migration progresses, and thus gradually increases after the time t11 when the migration has progressed to some extent in the entire printed circuit board 21. In this case, as shown in FIG. 6D, the inspection device 51 performs the ammeter 5 at every preset sampling period TS.
3 and the resistance value RP between the circuit patterns 22a and 22b is calculated on the basis of the value measured by the voltmeter 54, and the calculation result is recorded. Therefore, as shown in FIG. 4C, the resistance value RP at the time t12 falls below the preset threshold value RPTH for the first time. Therefore, the inspection device 51 detects the time t12 as the migration occurrence time. On the other hand, after the end of the inspection, the actual state of the printed circuit board 21 is determined based on the time from the start of the inspection to time t12, the environmental conditions in the thermo-hygrostat 31, the output voltage value of the DC voltage source 12, and the like. Estimate the useful life in the usage environment.

[0007]

However, the conventional migration inspection method has the following problems. That is, the printed circuit board 21 is not used alone, but is actually used with circuit components mounted thereon. In this case, the circuit components are generally mounted on the printed circuit board 21 by soldering. For this reason, even if the printed circuit board 21 is washed to remove deposits at the time of soldering, residues such as flux and resin are left on the printed circuit board 21 without being completely removed.
Therefore, halogen ions such as chlorine ions contained in the residue accelerate ionization of copper, which is a material of the circuit pattern, to further promote the migration. As a result, the actual service life of the printed circuit board 21 is significantly shorter than the service life estimated based on the migration inspection result of the printed circuit board 21 alone. For this reason, the conventional method of inspecting the occurrence of migration on the printed circuit board 21 alone is difficult to provide an inspection result for evaluating the actual migration resistance of the printed circuit board 21 in a component mounted state. There is a point.

The present invention has been made in view of the above problems, and provides a migration inspection method and a migration inspection capable of providing an inspection result suitable for evaluating practical migration resistance of a circuit board. The main purpose is to provide a device.

[0009]

In order to achieve the above object,
2. The migration inspection method according to claim 1, wherein a DC voltage is applied between two circuit patterns formed on the circuit board to be inspected, and at least one of a conduction current between the two circuit patterns, an inter-pattern voltage, and an inter-pattern resistance.
In a migration inspection method for measuring two measured values and detecting occurrence of migration based on the measured values, at least one circuit component is mounted on a circuit board.
It is characterized by measuring two measured values.

In this migration inspection method, a migration inspection is performed on a circuit board to be inspected in an actual use state where circuit components are mounted. In this case, in the circuit board, migration is promoted by ions contained in the attached residue. That is, migration proceeds in the same manner as the degree of progress under actual use conditions. For this reason, in this inspection method, by measuring a conduction current between circuit patterns, which increases due to migration that may occur on a circuit board under actual use conditions, an inspection that matches actual use conditions is performed. The result can be obtained. This makes it possible to accurately evaluate the migration resistance of the circuit board to be inspected based on the inspection result.

According to a second aspect of the present invention, there is provided a migration inspection method for measuring an inter-pattern voltage between two circuit patterns formed on a circuit board to be inspected and detecting occurrence of migration based on the measured value. The method is characterized in that a voltage between patterns is measured while the circuit board is operated.

The progress of migration between circuit patterns is also affected by the polarity and magnitude of the voltage applied between the circuit patterns. For this reason, even if the occurrence of migration is inspected with a constant voltage applied between circuit patterns externally, the degree of progress of migration differs when actual voltage values and polarities are applied between circuit patterns. There is. On the other hand, in this inspection method, the migration inspection is performed by actually operating the circuit board. Therefore, this inspection method detects the occurrence of migration that progresses under the use conditions in which the actual polarity and voltage are applied between the circuit patterns. This makes it possible to accurately evaluate the migration resistance of the circuit board to be inspected based on the inspection result.

According to a third aspect of the present invention, in the migration inspection method of the second aspect, the occurrence of migration is detected based on allowable voltage range column information for an inter-pattern voltage and a measured value of the inter-pattern voltage. It is characterized by.

In some circuit patterns, for example, an AC voltage line in which the voltage between circuit patterns during a normal operation changes periodically. In such a case,
For example, as a first example, when a circuit pattern to be inspected is short-circuited with another circuit pattern adjacent to the circuit pattern due to generation of a product by migration, as a second example, measurement is performed. In the case where the voltage value corresponding to the phase of the periodic voltage at the time of the above timing is a high voltage, the voltage between both circuit patterns to be inspected is always 0 V or less in the case of a short circuit through the product by migration. Not always. For this reason,
In a method of detecting that a short circuit or the like of a circuit pattern due to migration occurs when a measured value falls below the threshold value using a fixed threshold value, the detection itself may be inaccurate. On the other hand, in this inspection method, the occurrence of migration is detected on the condition that the voltage is out of an allowable voltage range that can fluctuate in a normal state. Therefore,
It is possible to accurately detect the occurrence of migration in the operating state.

According to a fourth aspect of the present invention, in the migration inspection method according to the third aspect, the allowable voltage range column information is such that the lower the absolute value of the center voltage of each allowable voltage range is, the lower the allowable value of the absolute value is. The ratio of the voltage range is set to be large.

The allowable voltage range column information may be set to an allowable voltage range obtained by adding a fixed ratio (for example, ± 10%) to the center voltage. On the other hand, when a voltage obtained by superimposing a periodic voltage on a DC is applied between the circuit patterns to be inspected, the DC voltage may fluctuate due to a change in environmental conditions or the like. In such a case, the voltage between the circuit patterns is measured particularly when the voltage value of the periodic voltage is a low voltage phase, and migration is determined based on whether or not the measured value falls within a certain allowable voltage range. When the occurrence is detected, the measured value may be out of the allowable voltage range even though no migration has occurred on the circuit board. In this inspection method, the allowable voltage range sequence information is created such that the ratio of the allowable voltage range to the absolute value of the center voltage increases as the absolute value of the center voltage decreases. Therefore, even when the DC voltage fluctuates in a state where a voltage obtained by superimposing a periodic voltage on the DC is applied between the circuit patterns to be inspected, it is possible to accurately detect the occurrence of the migration even when the DC voltage fluctuates. Becomes

According to a fifth aspect of the present invention, there is provided the migration inspection method according to the third or fourth aspect, wherein the voltage between the patterns of the circuit board during normal operation is measured as a center voltage, and an allowable value is determined based on the measured center voltage. It is characterized in that voltage range string information is created.

The central voltage of the voltage between the circuit patterns of the circuit board during normal operation is calculated by a desk-top calculation based on various conditions such as the circuit configuration of the circuit board, the constants of circuit components, and the power supply voltage supplied to the circuit board. It can also be calculated. However, such a calculation method requires complicated calculations and requires a long time. On the other hand, in this inspection method, after measuring the voltage between the circuit patterns of the circuit board during normal operation, the allowable voltage range column information may be created using the measured value as the center voltage. It becomes possible to create range column information.

According to a sixth aspect of the present invention, in the migration inspection method of the fifth aspect, the center voltage is sampled at a period of 1 / n (n is an integer) with respect to a sampling period of a measured value at the time of inspection. At the time of inspection, migration is performed based on the permissible voltage range column information corresponding to the center voltage sampled at a period equal to the sampling period of the measured value, including the permissible voltage range column information based on the center voltage corresponding to the measured value. Is detected.

The occurrence of migration may be detected based on allowable voltage range sequence information corresponding to the center voltage sampled at a sampling period equal to the sampling period of the measured value at the time of inspection. However, due to the mismatch between the sampling timing of the measured value and the sampling timing of the center voltage with respect to the phase of the periodic voltage applied between the circuit patterns to be inspected, the measured value and the corresponding center voltage There is a possibility that an error between the two may increase. On the other hand, in this inspection method, the center voltage is sampled n times as many times as the number of samples of the measurement value for one period of the periodic voltage at the time of inspection. For this reason, by using the allowable voltage range sequence information corresponding to the center voltage including the center voltage closest to the sampled measurement value and corresponding to the center voltage sampled at a period equal to the sampling period of the measurement value at the time of the inspection, the detection accuracy of the occurrence of migration can be improved. Can be increased.
In this case, the accuracy can be increased as n is increased.

According to a seventh aspect of the present invention, there is provided a migration inspection apparatus which intermittently measures an inter-pattern voltage between two circuit patterns formed on a circuit board to be inspected and detects occurrence of migration based on the measured value. The inspection apparatus is characterized in that a detection means is provided for detecting the occurrence of migration based on allowable voltage range sequence information for a voltage between circuit patterns on a circuit board in an operating state and a measured value of the voltage between patterns.

According to a seventh aspect of the present invention, in the migration inspection apparatus according to the seventh aspect, the allowable voltage range column information is such that the lower the absolute value of the center voltage of each allowable voltage range is, the lower the allowable value of the absolute value is. The ratio of the voltage range is set to be large.

According to a ninth aspect of the present invention, there is provided the migration inspection apparatus according to the seventh or eighth aspect, wherein a voltage between patterns when the circuit board is normally operated is measured as a center voltage, and based on the measured center voltage. It is characterized by comprising a data creating means for creating voltage range sequence information.

According to a tenth aspect of the present invention, in the migration inspecting apparatus according to the ninth aspect, the data generating means has a cycle of 1 / n (n is an integer) with respect to a sampling cycle of the measured value at the time of the inspection. The permissible voltage range sequence information is created based on the sampled center voltage, and the detecting means includes the permissible voltage range sequence information based on the center voltage corresponding to the measured value, and the center sampled at a period equal to the sampling period of the measured value. It is characterized in that occurrence of migration is detected based on allowable voltage range sequence information corresponding to the voltage.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a migration inspection method and a migration inspection apparatus according to the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 1, the inspection apparatus 1 includes a voltmeter 2, a timer 3, a CPU 4, a display unit 5, a memory 6, and an operation unit 7. Here, the voltmeter 2 includes circuit patterns 22a and 22 in a printed circuit board 21 to be inspected.
The voltage VP between b is input via the probes 41a and 41b, and the voltage waveform of the voltage VP is output to the CPU 4. The timer 3 has a clock signal CL1 having a period TS1 and a clock signal C2 having a period TS2 twice as long as the period TS1.
L2 and a time signal ST corresponding to the current time
Is output in accordance with a control signal SC output from. CPU
Reference numeral 4 denotes a detection unit, a data creation unit, and a recording control unit in the present invention, which measures the voltage value of the voltage VP by sampling the voltage waveform output from the voltmeter 2 in synchronization with the clock signal CL1. , Voltmeter 2
Is sampled in synchronization with the clock signal CL2, and allowable voltage range sequence information is created based on the sampled data. The display unit 5 includes a CPU 4
The voltage value of the voltage VP measured as a result, an inspection result, and the like are displayed. The memory 6 corresponds to the recording means in the present invention and records the measured voltage value of the voltage VP and the like. The operation unit 7 includes a measurement start switch, a measurement end switch, and the like.

On the other hand, the printed circuit board 21 to be inspected is incorporated in the electronic equipment 11 together with a DC voltage source 12 for operating each circuit in the printed circuit board 21 and a power switch 13 as shown in FIG. . The printed circuit board 21 includes a chip resistor 14 and a chip capacitor 15.
Are mounted between the circuit patterns 22a and 22b, and the circuit patterns 22a and 22b are connected to the power supply circuit patterns 22c and 22d via various circuit components. The power supply circuit patterns 22c and 22d are provided with power supply input terminals 16a and 16b, and the DC voltage source 12 is connected to the power supply input terminals 16c and 16d via the power switch 13. The printed circuit board 21
Is operating normally, both circuit patterns 22a, 2a
As shown in FIG. 2A, a sine wave voltage having a period T0 output from an oscillation circuit (not shown) is applied between the terminals 2b.

Next, referring to FIGS. 2 and 3, a description will be given of a migration inspection method by the inspection apparatus 1. FIG.

First, the electronic device 11 is set in the constant temperature / humidity chamber 31. Next, the circuit pattern 2 of the printed circuit board 21
Probes 41a and 41b are connected to 2a and 22b, respectively. Next, the power switch 13 is turned on to turn on the DC voltage source 1.
By supplying the DC voltage from the power supply terminal 2 between the power input terminals 16a and 16b to operate each circuit in the printed circuit board 21, the voltage data generation start switch of the operation unit 9 is operated. At this time, the CPU 4
The voltage data (corresponding to the center voltage in the present invention) of the sine wave voltage applied between a and 22b is sucked up.
Specifically, by outputting the control signal SC, the CPU 4 outputs the clock signal CL1 from the timer 3 at each sampling period TS1 shown in FIG. The voltage value of the voltage VP is measured by sampling in synchronization with the clock signal CL1. In this case, the CPU 4 measures the voltage VP for a time sufficiently longer than the period T0 of the sine wave voltage, and records the measured value in the memory 6.

Next, the CPU 4 searches for the lowest value from the recorded measured values. In this case, the voltage V1 sampled at the time t1 is searched for as the lowest value, as shown in FIG. Thereafter, the CPU 4 records the voltage V1 to the voltage Vn sampled at the time tn immediately before the next lowest value in the memory 6. Then, CPU
4 denotes upper threshold values VU1 to VUn obtained by adding a predetermined value (for example, 1 volt) to each of the voltages V1 to Vn;
ＶVn are calculated by subtracting a predetermined value (for example, 1 volt) from each of the threshold values VL1〜VLn, and both calculated threshold values are recorded in the memory 6 in association with the respective voltages V1〜Vn.

Next, the migration inspection will be described with reference to FIG. In this inspection, when the measurement start switch of the operation unit 9 is operated, the CPU 4
By outputting C, a clock signal CL for inspection having a period TS2 shown in FIG.
2 is output, and the voltage waveform output from the voltmeter 2 is sampled in synchronization with the clock signal CL2 to measure the voltage value of the voltage VP. Next, the CPU 4 detects the measured value closest to the voltage V1, which is the lowest value previously searched, among the measured values. In this case, assuming that the measured value VP1 at the time tP1 is equivalent, the CPU 4 calculates the measured value VP1 from the upper threshold VU1 corresponding to the voltage V1 to the lower threshold VU1.
It is determined whether the voltage is within the voltage range up to L1. As a result of the fact that the migration has not progressed at the beginning of the test, the measured value VP1 is included in the voltage range at this time, so that the CPU 4 determines that the migration has not occurred.

Next, the CPU 4 synchronizes the two circuit patterns 22a, 22a with the cycle signal TS2 in synchronization with the clock signal CL2.
b, the voltage VP is sequentially measured, and the measured values VP2 to VPn are
It is determined whether or not it is within the voltage range of the corresponding upper threshold and lower threshold. In this case,
The CPU 4 correlates the measured value VP1 with the voltage V1.
A voltage data string (V3, V5,..., Vn-2) including the voltage V1 and sampled at a period equal to the period TS2 of the measurement value at the time of the migration inspection.
, Vn), respectively. Specifically, in this case, VU1, VU3,... VU (n−
2), VUn is used, and VL1, VL
3, VL (n-2) and VLn are used. CPU4
When the inspection is performed on each measurement value in one cycle of the sine wave voltage, the inspection is repeated based on each measurement value of the sine wave voltage in each subsequent cycle and the corresponding upper and lower thresholds. Execute.

Eventually, the migration progresses, and both circuit patterns 22 are set at an intermediate time between time tP (m-1) and time tPm.
a and 22b are short-circuited via dendrite or CAF which is a product of migration. At this time, since the two circuit patterns 22a and 22b are in a state where resistors having low resistance values are equivalently connected, the voltage VP decreases. Next, since the measured value VPm sampled at the time tPm is out of the voltage range from the upper threshold value VUm to the lower threshold value VLm corresponding to the measured value VPm, the CPU 4 determines that migration has occurred at the time tPm. Determine. At the same time, the CPU 4 records the time tPm in the memory 6 based on the time signal ST output from the timer 3 at that time, and causes the display unit 5 to display that migration has occurred.

As described above, according to the inspection apparatus 1, C
Since the PU 4 determines the occurrence of migration based on each measured value and the voltage range from the upper threshold to the lower threshold corresponding to each of the measured values, the PU 4 determines whether the migration occurs between the two circuit patterns 22a and 22b. , The occurrence of migration can be detected with high accuracy even when a periodic voltage is applied. Further, in the inspection apparatus 1, twice as many voltage data are generated as the number of samplings of the measurement value for one period of the periodic voltage at the time of the migration inspection. Therefore, the circuit pattern 22
The sampling timing of the measured value and the sampling timing of the voltage data with respect to the phase of the periodic voltage applied between the a and 22b can be closer to each other, whereby the measured value and the corresponding voltage data can be compared. As a result of reducing the error between the voltage value and the voltage value, the occurrence of migration can be detected with higher accuracy. Further, even if the DC voltage included in the voltage VP fluctuates,
The upper and lower thresholds are set such that the lower the absolute value of the voltage value of the voltage data is, the higher the ratio of the voltage range to the absolute value is. Can be detected. In addition, according to the inspection apparatus 1, not only migration occurs between the circuit patterns 22a and 22b to be inspected, but also when migration occurs in other circuit patterns, the circuit pattern 22a and 22b As long as the voltage VP is affected, the occurrence of the migration can be detected.

It should be noted that the present invention is not limited to the above-described embodiment, and the configuration and the inspection method can be appropriately changed. For example, in the embodiment of the present invention, the printed circuit board 2
Although the example of detecting the occurrence of migration by operating No. 1 has been described, it is also possible to inspect the printed circuit board 21 on which circuit components are mounted in a non-operating state. In this case, while applying a DC voltage to the circuit patterns 22a and 22b to be inspected on the printed circuit board 21, one of the conduction current, the inter-pattern voltage and the inter-pattern resistance between the two circuit patterns 22a and 22b is measured. The occurrence of migration can be inspected based on the measured value. Further, in the embodiment of the present invention, an example in which a periodic voltage is applied to both circuit patterns 22a and 22b has been described. However, even when a DC voltage is applied, the measured inter-pattern voltage and The occurrence of migration can be detected based on the preset threshold value.

In the embodiment of the present invention, the occurrence of migration between only the two circuit patterns 22a and 22b is inspected. However, the present invention is not limited to this, and the occurrence of migration between many other circuit patterns is not limited to this. May be configured to be inspected simultaneously. Further, in the embodiment of the present invention, the sampling period TS1 for creating the upper threshold value and the lower threshold value is set to half the sampling period TS2 at the time of the migration inspection. However, the present invention is not limited to this. An equal period may be used, or the period TS1 may be 1 / n of the period TS2 (n is an integer of 3 or more).
Of course, it can also be set to.

In the embodiment of the present invention, the CPU 4
Creates the upper and lower thresholds prior to the actual inspection, but the present invention is not limited to this,
Both thresholds can be created based on the measurement values measured at the beginning of the migration inspection. further,
Although the CPU 4 creates the upper threshold value and the lower threshold value by adding and subtracting a predetermined voltage value to and from the measured value of the voltage VP, the present invention is not limited to this. An upper threshold and a lower threshold may be created by multiplying each ratio.

[0038]

As described above, according to the migration inspection method of the first aspect, the occurrence of migration is detected by detecting the occurrence of migration based on the measurement value measured with the circuit components mounted on the circuit board. Inspection results that match the use conditions can be obtained. This makes it possible to accurately evaluate the migration resistance of the circuit board to be inspected based on the inspection result.

According to the migration inspection method of the present invention, by measuring the inter-pattern voltage in a state where the circuit board is operated, the actual polarity and voltage are applied between the circuit patterns. Can detect the occurrence of migration that proceeds. As a result, the migration resistance of the circuit board to be inspected can be accurately evaluated based on the inspection result.

Further, according to the migration inspection method of the third aspect and the migration inspection apparatus of the seventh aspect, the occurrence of migration is determined based on the allowable voltage range column information for the inter-pattern voltage and the measured value of the inter-pattern voltage. By detecting, even if the voltage between circuit patterns periodically changes, it is possible to accurately detect the occurrence of migration.

According to the migration inspection method of the fourth aspect and the migration inspection apparatus of the eighth aspect, the lower the absolute value of the center voltage of each allowable voltage range is, the lower the ratio of the allowable voltage range to the absolute value is. Is created so that migration can occur accurately even when a voltage in which a periodic voltage is superimposed on DC is applied between circuit patterns to be inspected. Can be detected.

According to the migration inspection method of the fifth aspect and the migration inspection apparatus of the ninth aspect, the voltage between the patterns on the circuit board during the normal operation is measured as the center voltage, and based on the measured center voltage. By creating the allowable voltage range string information, the allowable voltage range string information can be created easily and in a short time.

Furthermore, according to the migration inspection method of the sixth aspect and the migration inspection apparatus of the tenth aspect, the number of samplings of the measurement value for one period of the periodic voltage at the time of inspection is n times as large as the number of samplings. The generation of the migration can be detected with high accuracy by sampling the center voltage of.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an inspection system by an inspection device according to an embodiment of the present invention.

FIGS. 2A and 2B are diagrams for explaining a process of creating voltage data and upper and lower threshold values in the inspection apparatus according to the embodiment of the present invention; FIG. FIG. 5B is a voltage transition diagram showing transitions of voltages V1 to Vn related to voltage data, upper limit threshold and lower limit threshold, and FIG. 6B is a sampling timing diagram showing timing of sampling voltage VP between patterns.

3A and 3B are diagrams for explaining a process of detecting the occurrence of migration of the inspection apparatus according to the embodiment of the present invention, wherein FIG. 3A is a voltage waveform diagram of a voltage VP between circuit patterns, and FIG. () Is a sampling timing chart showing the timing of sampling the voltage VP between circuit patterns.

FIG. 4 is a block diagram showing an inspection system using a conventional inspection device.

5A and 5B are diagrams for explaining the operation of the conventional inspection apparatus, wherein FIG. 5A is a voltage transition diagram showing a transition of a voltage VP between circuit patterns, and FIG. 5B is a diagram for conducting between circuit patterns. FIG. 3C is a diagram showing a transition of a conduction current showing a transition of a current IP, FIG. 3C is a diagram showing a transition of an insulation resistance showing a transition of a calculated resistance value RP between circuit patterns, and FIG. FIG. 5 is a sampling timing chart showing a timing of sampling a conduction current.

FIG. 6 is a state diagram showing a migration occurrence state for explaining the principle of migration occurrence.

[Description of Signs] 1 Inspection device 2 Voltmeter 4 CPU 14 Chip resistor 15 Chip capacitor 21 Printed circuit board 22a Circuit pattern 22b Circuit pattern

Claims (10)

[Claims] 1. A method in which a DC voltage is applied between two circuit patterns formed on a circuit board to be inspected, and at least one of a measured value of a conduction current, an inter-pattern voltage, and an inter-pattern resistance between the two circuit patterns is measured. A migration inspection method for measuring and detecting occurrence of migration based on the measurement value, wherein the at least one measurement value is measured in a state where a circuit component is mounted on the circuit board. 2. A migration inspection method for measuring an inter-pattern voltage between two circuit patterns formed on a circuit board to be inspected and detecting occurrence of migration based on the measured value, wherein the circuit board is operated. Measuring the inter-pattern voltage in a state of being moved. 3. The migration inspection method according to claim 2, wherein occurrence of migration is detected based on allowable voltage range column information for the inter-pattern voltage and a measured value of the inter-pattern voltage. 4. The allowable voltage range column information is such that the lower the absolute value of the center voltage of each allowable voltage range is, the larger the ratio of the allowable voltage range to the absolute value is set. Item 4. The migration inspection method according to Item 3. 5. The apparatus according to claim 3, wherein the inter-pattern voltage of the circuit board during a normal operation is measured as the center voltage, and the allowable voltage range sequence information is created based on the measured center voltage. Or the migration inspection method according to 4. 6. The sampling of the center voltage at a cycle of 1 / n (n is an integer) with respect to a sampling cycle of the measurement value at the time of inspection, and at the time of inspection, an allowance based on the center voltage corresponding to the measurement value. 6. The occurrence of migration is detected based on the allowable voltage range sequence information corresponding to the center voltage that includes voltage range sequence information and that is sampled at a period equal to the sampling period of the measurement value. The migration inspection method described. 7. A migration inspection apparatus which intermittently measures an inter-pattern voltage between two circuit patterns formed on a circuit board to be inspected and detects the occurrence of migration based on the measured value. A migration inspection apparatus, comprising: detection means for detecting occurrence of migration based on allowable voltage range sequence information for the circuit pattern voltage of the circuit board and a measured value of the pattern voltage. 8. The allowable voltage range column information is such that the lower the absolute value of the center voltage of each allowable voltage range is, the larger the ratio of the allowable voltage range to the absolute value is set. Item 7. A migration inspection device according to Item 7. 9. A data generating means for measuring the inter-pattern voltage at the time of normal operation of the circuit board as the center voltage, and for generating the permissible voltage range sequence information based on the measured center voltage. The migration inspection apparatus according to claim 7 or 8, wherein: 10. The data creating means creates the allowable voltage range sequence information based on the center voltage sampled at a cycle of 1 / n (n is an integer) with respect to a sampling cycle of the measured value at the time of inspection. And the detecting means comprises:
The allowable voltage range column information based on the center voltage corresponding to the measured value is included, and the migration of the migration is performed based on the allowable voltage range column information corresponding to the center voltage sampled at a cycle equal to the sampling cycle of the measured value. The migration inspection apparatus according to claim 9, wherein occurrence is detected.