JP2000338168A - Device for inspecting circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a manufacturing cost and to shorten an inspection time. SOLUTION: This device is a circuit board inspecting device 1 provided with a base electrode 7 arranged on one side of a circuit board PC of an inspection object and a contact type probe 3a arranged in the other face side of the board PC to inspect wire-breaking and short-circuit in a conductor pattern of the inspection object based on an electrostatic capacity measured by impressing an alternating current signal SAC between the conductor pattern of the inspection object and the base electrode 7 in the condition that the contact type probe 3a contacts with the conductor pattern. In the device 1, the alternating current signal SAC having a frequency to allow measurement for insulation resistance between the conductor pattern of the inspection object and other conductor pattern is impressed, and insulation inspection as to the conductor pattern of the inspection object is carried out based on the measured electrostatic capacity and a prescribed allowable electrostatic capacity range.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board inspection apparatus capable of executing both a disconnection short-circuit inspection and an insulation inspection of a plurality of conductor patterns on a circuit board to be inspected.

[0002]

2. Description of the Related Art A disconnection short-circuit test is performed on a number of conductor patterns such as conductor patterns PA and PB (hereinafter, referred to as "conductor pattern P" when not distinguished) formed on a circuit board PC shown in FIG. As a circuit board inspection device to be obtained, a circuit board inspection device 21 shown in FIG. 5 is conventionally known. The circuit board inspection device 21 includes a control device 22, a contact type probe 3a, a probe moving mechanism 4a that moves the probe 3a in the XYZ directions (vertical, horizontal, and height directions) with respect to the circuit board PC to be inspected, and An inspection jig 5 is provided. In this case, the inspection jig 5 includes a base board 6, a base electrode 7, and an insulating film 8, and is configured such that the circuit board PC can be mounted on the insulating film 8.

In the circuit board inspection apparatus 21, a circuit board PC is set on the insulating film 8 of the inspection jig 5 at the time of inspection. Next, the control device 22 drives the probe moving mechanism 4a to bring the probe 3a into contact with the conductor pattern P to be inspected, and in this state, transmits the inspection AC signal SAC of, for example, about 160 KHz between the probe 3a and the base electrode 7. By applying the voltage, the capacitance between the conductor pattern P and the base electrode 7 is measured. At this time, the control device 22 sets the allowable range (for example, the actual capacitance ± 20) to the actual capacitance previously absorbed from the non-defective circuit board PC.
%), If the measured capacitance is smaller than the lower limit of the allowable range, it is determined that the conductor pattern P is disconnected. If the measured capacitance is larger than the upper limit of the allowable range, the conductor pattern P is not. It is determined that P is short-circuited. This process is sequentially performed on the other conductor patterns P, and when it is determined that no disconnection short circuit has occurred in all the conductor patterns P, the circuit board PC to be inspected is determined to be a non-defective circuit board.

However, even though the circuit board inspection apparatus 21 can detect the presence of the conductor patterns P, P which are completely short-circuited by a solder bridge or the like, the conductor patterns P, P have a mutual resistance of, for example, several MΩ. When such a high-resistance insulation failure occurs, there is a problem that the insulation failure cannot be detected. That is, the capacitance between the conductor pattern P to be inspected and the base electrode 7 is 1
It is about pF to several tens pF. For this reason, for example, 10p
In the case of F, the impedance is about 100 KΩ. On the other hand, the impedance at the location of poor insulation is several MΩ. Therefore, the impedance of the insulation failure part is actually a measurement error,
It is very difficult to detect its presence. For this reason, the circuit board PC for which the conductor pattern P has been subjected to the disconnection short-circuit inspection is normally not used for the insulation inspection by the capacitance measurement, but is used together with the insulation inspection circuit board inspection apparatus 31 shown in FIG. Insulation inspection is performed by doing.

A circuit board inspection apparatus 31 includes a probe 3b disposed above or below a circuit board PC to be inspected, and a probe moving mechanism 4b for moving the probe 3b in the XYZ directions, instead of the inspection jig 5. And In this circuit board inspection device 31, the control device 32 drives the probe movement mechanism 4a to bring one probe 3a into contact with the conductor pattern P to be inspected, and the probe movement mechanism 4a
b to drive the other probe 3 to another conductor pattern P.
b is contacted. Next, an inspection DC signal SDC of, for example, about 100 V is applied between the conductor patterns P, P, and the insulation resistance is measured. At this time, when the measured insulation resistance is less than a predetermined threshold value (for example, 10 MΩ), the control device 32 determines that the conductor pattern P has insulation failure. This process is sequentially performed on all the conductor patterns P, P,..., And when it is determined that there is no insulation failure in all the conductor patterns P, the circuit board PC to be inspected is determined to be a non-defective circuit board.

On the other hand, a circuit board inspection apparatus 41 shown in FIG. 7 has been conventionally known as a circuit board inspection apparatus capable of performing both a disconnection short-circuit inspection and an insulation inspection of a conductor pattern P by one unit. The circuit board inspection device 41 is of a so-called pin board type, and has many probes 42, 42.
.. inspection jigs 43a, 43b each provided with
And scanner sections 44a and 4 for selectively switching the probe 42
4b, and a control device 46 having a control unit 45 for executing various controls.

In this circuit board inspection apparatus 41, with the circuit board PC to be inspected set at a predetermined position, the control unit 45 activates a drive device (not shown) to activate the inspection jig 43.
a and 43b are respectively moved to the circuit board PC side. The control unit 45 selects one specific probe 42 by controlling the selection switching of the scanner units 44a and 44b in a state where each probe 42, 42... Is in contact with the circuit board PC, and selects the specific probe 42. A DC test signal SDC is applied between the probe 42 and all other probes 42, 42,. Next, the insulation resistance during that time is measured, and when it is less than a predetermined threshold value, it is determined that a short circuit or insulation failure exists in the specific conductor pattern P. Then, specific 1
By sequentially selecting one probe, the insulation test is sequentially performed on all the conductor patterns P, P,.
The disconnection is inspected by bringing the probes 42 into contact between the ends of each conductor pattern P and measuring the resistance value between them. When it is determined that there is no disconnection, short circuit, or insulation failure in all the conductor patterns P, it is determined that the inspection target circuit board PC is a non-defective circuit board.

[0008]

However, the conventional circuit board inspection apparatuses 21, 31, 41 have the following problems. That is, as described above, since the insulation inspection cannot be performed on the circuit board inspection apparatus 21 unless the circuit board inspection apparatus 31 is used in combination, the price of the entire inspection system substantially increases substantially. There is a point. Further, even when the circuit board inspection apparatus 31 is used, for example, when 1000 independent conductor patterns P are formed on one circuit board PC, all of the pair of conductor patterns P, P In order to perform an insulation test on the combination of the above, the number of times of the test is an enormous number of about 500,000. Therefore, if the movement of the probes 3a and 3b requires about 0.1 second, the total inspection time is about 13.
9 hours. In this case, the insulation test can be performed only between the specific conductor patterns P. However, even in such a case, when a plurality of power supply layers are formed on the multilayer substrate, the number of measurements naturally increases. . Therefore, the conventional circuit board inspection apparatus 31 has a problem that the inspection time is lengthened.

Further, the circuit board inspection apparatus 41 requires dedicated inspection jigs 43a and 43b. In this case, the inspection jigs 43a and 43b are generally expensive, and are required for each type of the circuit board PC. Therefore, there is a problem that not only the manufacturing cost but also the running cost of the circuit board inspection device 41 rises. further,
Inspection of many types of circuit boards PC requires many inspection jigs 43a and 43b, so that it is difficult to secure a storage place for the jigs 43a and 43b.

[0010] The present invention has been made in view of the above problems, and has as its main object to provide a circuit board inspection apparatus capable of reducing the manufacturing cost and the inspection time.

[0011]

In order to achieve the above object, a circuit board inspection apparatus according to the present invention comprises a base electrode provided on one surface of a circuit board to be inspected, and a base electrode provided on the other surface of the circuit board. A contact type probe is provided, and an AC signal for inspection is applied between the conductor pattern to be inspected and the base electrode in a state where the contact type probe is in contact with the conductor pattern to be inspected. In a circuit board inspection apparatus for inspecting a disconnection short circuit of a conductor pattern to be inspected based on an AC signal for inspection at a frequency capable of measuring an insulation resistance between the conductor pattern to be inspected and another conductor pattern, the measured static electricity is measured. The insulation test is performed on the conductor pattern to be inspected based on the capacitance and a predetermined allowable capacitance range.

According to a second aspect of the present invention, in the circuit board inspection apparatus according to the first aspect, the frequency f of the AC signal for inspection is such that the capacitance between the conductor pattern to be inspected and the base electrode is a value C1. When the capacitance between the other conductor pattern and the base electrode is a value C2, the threshold value at the time of the insulation test is Rr, and the upper limit value of a predetermined allowable capacitance range is a value CL, CL <C1 + (C2 / (1+ (2 · π · f · R
r) ² )).

According to a third aspect of the present invention, there is provided the circuit board inspection apparatus according to the first or second aspect, wherein a pair of contact type probes is provided for the conductor pattern to be inspected which is determined to be defective in the insulation inspection. Insulation inspection is performed by measuring insulation resistance using a.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a circuit board inspection apparatus according to the present invention will be described below with reference to the accompanying drawings. Note that the same components as those of the conventional circuit board inspection apparatus 21 are denoted by the same reference numerals, and redundant description will be omitted.

First, the configuration of the circuit board inspection apparatus 1 will be described with reference to FIG.

The circuit board inspection apparatus 1 is configured to be able to simultaneously execute both an inspection for disconnection and short-circuit and an inspection for insulation of the conductor pattern P. Specifically, as shown in FIG. 1, the circuit board inspection apparatus 1 connects the control device 2 and the probes 3a and 3b (hereinafter, referred to as "probe 3" when not distinguished) to the circuit board PC to be inspected. XY
Probe moving mechanisms 4a and 4b that move in the vertical direction and the vertical direction (Z direction), respectively.
A “probe moving mechanism 4”) and an inspection jig 5.

As shown in FIG. 1, the control unit 2 includes a control unit 11 for executing various controls in circuit board inspection,
M12 and RAM 13 are provided. The control unit 11
A capacitance measurement process at the time of inspection, drive control of the probe moving mechanism 4, and a pass / fail determination process for the circuit board PC based on the measured capacitance are executed. ROM1
2 stores an operation program of the control unit 11 and the like;
M13 temporarily stores the calculation result of the control unit 11 and the like.

The capacitance measuring jig 5 includes a flat base plate 6 and a base electrode 7 provided on the upper surface of the base plate 6.
And a thin insulating film 8 attached to the upper surface of the electrode 6. The circuit board PC can be fixed to a predetermined position on the insulating film 8.

Next, an inspection process for the circuit board PC by the circuit board inspection apparatus 1 will be described.

First, the circuit board PC is fixed on the inspection jig 5. At this time, the lower surface of the circuit board PC is in contact with the upper surface of the insulating film 8 in the inspection jig 5, so that the circuit board PC and the base electrode 7 are kept separated from each other by a predetermined distance.

Next, the capacitance of each conductor pattern P is measured. At this time, the control unit 11 drives and controls the probe moving mechanisms 4a and 4b, for example, to bring the probe 3a into contact with the end PA1 of the conductor pattern PA shown in FIG. Next, the control unit 11 transmits the inspection AC signal SAC having a frequency of 16 KHz and a voltage of 10 V (any voltage between 1 V and 100 V) to the base electrode 7.
To the conductor pattern PA and the base electrode 7 based on the current flowing between the base electrode 7 and the probe 3a and the voltage of the test AC signal SAC. The capacitance Ca is measured. Next, depending on whether the measured capacitance Ca falls within a predetermined allowable range defined in advance based on the inspection reference capacitance absorbed from the non-defective circuit board PC, disconnection short-circuit and insulation failure of the conductor pattern PA are determined. Determine the presence or absence.

In this case, for example, it is assumed that a defective insulation portion PAB exists between the vicinity of the end PA2 of the conductor pattern PA and the vicinity of the end PB2 of the conductor pattern PB. Further, the insulation resistance of the defective insulation portion PAB is R, the capacitance between the conductor pattern PA and the base electrode 7 is a value C1, and the capacitance between the conductor pattern PB and the base electrode 7 is a value C1.
Let it be 2. In such a case, the two conductor patterns PA and PB and the defective insulation part PAB are equivalently equivalent to an equivalent circuit in which the capacitances C1 and C2 are connected in parallel via the insulation resistance R as shown in FIG. Equivalent circuit EC1 represented by EC1
Is also represented as an equivalent circuit EC2 shown in FIG. The capacitance C2 is the capacitance of one conductor pattern PB which may cause insulation failure among a large number of conductor patterns P. Here, the real part (conductance) of the admittance Y of the entire equivalent circuit EC2
Is G, the measured capacitance Ca is equal to the imaginary part (susceptance), and the admittance is represented by the following equation. Y = G + jωCa where ω = 2πf and f are the frequencies of the test AC signal SAC.

The conductance G and the measured capacitance Ca are represented by the following equations by the conversion operation. G = (ω · C2) ² · R / (1+ (ω · C2 · R) ² ) ··· Equation Ca = C1 + (C2 / (1+ (ω · C2 · R) ² )) ··· ·formula

According to the equation, when the insulation state is good and the insulation resistance R is infinite, the measured capacitance Ca is equal to the capacitance C1, and the insulation resistance R is 0Ω in the short-circuit state.
In this case, it can be understood that the measured capacitance Ca is the sum of the capacitance C1 and the capacitance C2 (C1 + C2). In this case, the capacitances C1 and C2 are determined by the good circuit board P
It is known because it has been previously absorbed from C as a reference capacitance for inspection. Also, the insulation resistance R is known because it is an inspection reference value when it is classified into a good product and a defective product. The inspection threshold value Rr of the insulation resistance R is, for example, 10M
Ω, and the actual capacitances of the capacitances C1 and C2 are 2 pF and 3 pF, respectively.

Therefore, in the disconnection inspection, the measured capacitance Ca of the conductor pattern PA is equal to the capacitance C1.
100% to 7 with respect to the test reference capacitance (2 pF)
It is determined whether it is within the range of 0%, and when it is less than 70%, it is determined that the wire is disconnected.

On the other hand, the short-circuit insulation inspection is determined based on the following principle. That is, the inspection AC signal SAC
Is set to a high frequency, since the insulation resistance R is high, as described above, the impedance (several MΩ) of the insulation failure portion PAB, the conductor pattern PB and the base electrode 7
The total impedance of the intervening capacitance C2 (3 pF) with the series circuit is about a measurement error with respect to the impedance of the capacitance C1 (2 pF) between the conductor pattern PA and the base electrode 7. However, since the insulation resistance R is a pure resistance component, it has a constant value without depending on the frequency of the test AC signal SAC. Therefore, by setting the frequency of the test AC signal SAC to a somewhat lower frequency, the capacitance C1,
The impedance of C2 is substantially increased. In this case, since the influence of the magnitude of the insulation resistance R is easily reflected on the measured capacitance Ca, it is possible to detect the presence of the insulation failure portion PAB. Specifically, in case of short circuit or insulation failure,
Since the measured capacitance Ca of the conductor pattern PA becomes larger than the reference capacitance for inspection, the conductor pattern PA
Is set to, for example, 120% with respect to the inspection reference capacitance.
% (Set in advance in the range of% to 130%) is the upper limit value CL.

In this case, in order for the measured capacitance Ca of the conductor pattern PA in which insulation failure has occurred to exceed the upper limit CL, the condition of the frequency f1 of the test AC signal SAC is expressed by the following equation. . CL <Ca = C1 + (C2 / (1+ (2 · π · f1 · Rr) ² )) ··· Formula Specifically, if an insulation failure occurs in the conductor pattern PA, the inspection AC signal When the frequency of the SAC is changed, the measured capacitance Ca of the conductor pattern PA has the frequency characteristic shown in FIG.
As shown in the drawing, when the test AC signal SAC has a somewhat high frequency, the measured capacitance Ca is determined by the capacitance C1 between the conductor pattern PA and the base electrode 7 despite the presence of insulation failure. It can be understood that there is almost no change. Also, the capacitance C2 of the conductor pattern PB
The influence on the measured capacitance Ca due to the above becomes more remarkable as the frequency of the test AC signal SAC becomes lower than the frequency fs shown in FIG. It can be understood that the capacitance Ca exceeds the upper limit CL.

For this reason, when the measured capacitance Ca when the test AC signal SAC having a frequency lower than f1 is used exceeds the upper limit value CL, a voltage lower than the threshold value Rr is set between the conductor patterns PA and PB. It can be determined that insulation failure of insulation resistance has occurred. Therefore, the control unit 11
When the measured capacitance Ca exceeds the upper limit CL, it is determined that a short circuit or insulation failure has occurred in the conductor pattern PA, and the pattern number of the conductor pattern PA is stored in the RAM 13.
To memorize. In consideration of manufacturing variations of the circuit board PC and variations in the measured capacitance Ca, it is preferable to set a margin by setting the frequency of the test AC signal SAC slightly lower than f1. In this case, it is possible to improve the accuracy of determining whether or not there is a short circuit or insulation failure. However, when the capacitance C2 between the conductor pattern PB and the base electrode 7 is sufficiently smaller than the capacitance C1 between the conductor pattern PA and the base electrode 7, the capacitance C1
In this case, it is of course possible to determine in the short-circuit insulation test for the conductor pattern PB that a short-circuit insulation defect has occurred in the conductor pattern PB.

The control unit 11 performs the above-described disconnection inspection at each end of each conductor pattern P (for example, ends PA2, PA3, PB1,
PB2, PB3...) And a short-circuit / insulation test are sequentially performed on each conductor pattern P, and a circuit board PC determined to be normal in all tests is determined as a non-defective circuit board PC. On the other hand, when the pattern number of the conductor pattern PA in which the short circuit or insulation failure has occurred is stored in the RAM 13, the control unit 11 insulates the conductor pattern P of the pattern number using the probes 3a and 3b. Perform inspection. In this insulation inspection, the control unit 11 drives the probe moving mechanism 4a to bring the probe 3a into contact with the conductor pattern P to be inspected, and also drives the probe moving mechanism 4b to contact the conductor pattern P. A plurality of conductor patterns P which may cause insulation failure between them are sequentially contacted, and each time the insulation resistance R is measured. As a result, with respect to the conductor pattern P determined to be defective in insulation in the short-circuit insulation test, it is possible to inspect with which conductor pattern P the degree of insulation resistance R causes insulation failure. As a result, the reliability of the insulation inspection can be increased, and the location of the insulation failure can be specified.
In this case, unlike the insulation inspection by the conventional circuit board inspection apparatus 31, the insulation inspection may be performed only on the conductor pattern P determined to have an insulation failure, so that the insulation inspection time is greatly reduced. Can be shortened.

As described above, according to the circuit board inspection apparatus 1, the presence or absence of disconnection, short circuit, and insulation failure can be simultaneously inspected based on the measured capacitance Ca measured for each conductor pattern P. In addition, unlike the conventional circuit board inspection apparatus 31 which needs to perform an insulation test on all combinations of a pair of conductor patterns P and P, the insulation test may be performed for each conductor pattern P. Can be greatly reduced. In addition, the reliability of the insulation test can be increased by performing the insulation test on the conductor pattern P determined to be defective in the short-circuit insulation test by measuring the insulation resistance using the pair of probes 3a and 3b. Thus, the location of the insulation failure can be reliably specified.

The present invention is not limited to the configuration shown in the above-described embodiment. For example, in the embodiment of the present invention, an example in which the short-circuit insulation test is performed using the contact type probe 3 has been described. However, it is possible in principle to perform the test using a non-contact type capacitance measurement probe. . Further, the frequency and voltage value of the inspection AC signal SAC are not limited to the numerical values shown in the embodiment of the present invention, but can be changed as appropriate. Further, a configuration may be adopted in which the frequency f of the inspection AC signal SAC can be varied, and the frequency can be varied according to each inspection reference capacitance between the conductor pattern P to be inspected and the base electrode 7. In this case, insulation failure of the conductor pattern P can be detected more reliably.

[0032]

As described above, according to the circuit board inspection apparatus of the first aspect, an inspection AC signal having a frequency capable of measuring the insulation resistance between the conductor pattern to be inspected and another conductor pattern is applied. Based on the measured capacitance and a predetermined allowable capacitance range, the presence / absence of disconnection, short-circuit, and insulation failure can be inspected simultaneously, so that the inspection time can be significantly reduced. Further, unlike the conventional circuit board inspection apparatus 41, no dedicated jig is required, so that the manufacturing cost and the running cost of the circuit board inspection apparatus can be significantly reduced.

According to the circuit board inspection apparatus of the second aspect, by using the inspection AC signal having the frequency f that satisfies the predetermined relational expression, it is possible to reliably detect the conductor pattern having the insulation failure. Can be.

Further, according to the circuit board inspection apparatus of the third aspect, the insulation inspection is performed on the conductor pattern to be inspected determined as insulation failure in the insulation inspection by measuring the insulation resistance using a pair of contact probes. By performing the above, the reliability of the insulation inspection can be improved, and the location of the insulation failure can be reliably specified.

[Brief description of the drawings]

FIG. 1 is a circuit board inspection apparatus 1 according to an embodiment of the present invention.
FIG. 2 is a configuration diagram showing the configuration of FIG.

2A is a circuit diagram of a schematic equivalent circuit EC1 of conductor patterns P, P to be inspected, and FIG. 2B is an equivalent circuit EC1.
FIG. 9 is a circuit diagram of an equivalent circuit EC2 for (1).

FIG. 3 is a frequency characteristic diagram of a measured capacitance Ca with respect to a frequency of an inspection AC signal SAC.

FIG. 4 is a pattern diagram showing an example of forming conductive patterns PA and PB on a circuit board PC.

FIG. 5 is a configuration diagram of a conventional circuit board inspection device 21.

FIG. 6 is a configuration diagram of another conventional circuit board inspection device 31.

FIG. 7 is a configuration diagram of still another conventional circuit board inspection device 41.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Circuit board inspection apparatus 2 Control apparatus 3a, 3b Probe 4a, 4b Probe moving mechanism 5 Inspection jig 7 Base electrode 11 Control part PC Circuit board SAC AC signal for inspection

Claims (3)

[Claims] 1. A test apparatus comprising: a base electrode disposed on one surface of a circuit board to be inspected; and a contact probe disposed on the other surface of the circuit board. A circuit board inspection apparatus for inspecting a disconnection short circuit of the conductor pattern to be inspected based on a capacitance measured by applying an inspection AC signal between the conductor pattern to be inspected and the base electrode in a state in which the conductor pattern is contacted In, applying the inspection AC signal of a frequency capable of measuring the insulation resistance between the conductor pattern to be inspected and another conductor pattern, based on the measured capacitance and a predetermined allowable capacitance range A circuit board inspection apparatus, wherein an insulation inspection is performed on the conductor pattern to be inspected. 2. The frequency f of the AC signal for inspection is such that the capacitance between the conductor pattern to be inspected and the base electrode is a value C1, and the capacitance between the other conductor pattern and the base electrode is C1. Is defined as a value C2, a threshold value at the time of the insulation test is Rr, and an upper limit value of the predetermined allowable capacitance range is a value CL, CL <C1 + (C2 / (1+ (2 · π · f)・ R
The circuit board inspection apparatus according to claim 1, wherein the following relational expression is satisfied: r) ² )). 3. An insulation test is performed on the conductor pattern to be inspected determined as insulation failure in the insulation inspection by insulation resistance measurement using a pair of the contact probes. Or the circuit board inspection device according to 2.