JP2002048833A - Circuit board inspecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the reliability of circuit board inspections based on a voltage measured through the use of contact probes. SOLUTION: The circuit board inspecting device 1 is provided with first and second contact probes 4a and 4b in which contact-side terminal parts are arranged close and next to each other in a non-contact state, third and fourth contact probes 4c and 4d in which contact-side terminal parts are arranged close and next to each other in a non-contact state, a measuring part 5 to measure the voltage between the second and third contact probes with a constant current for measurement supplied for a conductor pattern via the first and fourth contact probes, and a control part 6 to execute electric inspections on the conductor pattern on the basis of the results of measurement of the measuring part 5. The measuring part 5 measures the voltage between the contact probes 4a and 4b with a constant current supplied between the contact probes 4a and 4b arranged next to each other, and the control part 6 performs insulation inspections on both contact probes on the basis of the voltage measured by the measuring part 5.

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 for performing an electrical inspection on a conductor pattern to be inspected based on a measurement value measured by, for example, a four-terminal method.

[0002]

2. Description of the Related Art For example, when inspecting a disconnection of a conductor pattern formed on a circuit board to be inspected, a voltage between the both ends is measured by supplying a constant current for measurement between both ends of the conductor pattern. Then, the disconnection is inspected based on the resistance value obtained from the voltage value and the constant current value. In this case, a pair of contact probes for supplying a constant current (hereinafter, also referred to as “probes”) are respectively brought into contact with both end points, and a pair of voltage measurement probes are brought into contact with both end points. The resistance is measured by the four probe method. In this case, in order to perform measurement by the four-terminal method, the tips of the constant current supply probe and the voltage measurement probe should not be in direct contact with each other, but should be as close as possible to each other. Each must be in contact with the pattern. On the other hand, in a circuit board manufactured in recent years, since the fine pitch has been advanced, the conductor pattern to be measured has a very narrow width. Therefore, in order to simultaneously contact both the constant current supply probe and the voltage measurement probe with the narrow conductor pattern, it is necessary to hold the tips of both probes side by side at a close distance.

As an apparatus configured to be able to measure the resistance value by the four-terminal method of this type, a circuit board inspection apparatus 31 shown in FIG. 4 is conventionally known. This circuit board inspection device 3
Reference numeral 1 denotes a probe 4a attached to probe moving mechanisms 2a, 2b via probe holders 3, 3 (see FIG. 3).
-4d, a measuring unit 35 for performing voltage measurement by the four-terminal method using the probes 4a-4d, and the probe moving mechanism 2
and a control unit 36 for executing drive control for a and 2b and measurement control for the measurement unit 35. In this case, the probes 4a and 4b and the probes 4c and 4d
As shown in FIG. 3A, the tip portions are held by the probe holder 3 in a state where they are not in contact with each other and are juxtaposed at a close distance. In addition, the measuring unit 35
A constant current source 41 for supplying a DC constant current for measurement to the conductor pattern via the probes 4a and 4d;
and a voltmeter 42 for measuring a voltage between both end points of the conductor pattern detected by c.

In order to determine the quality of the circuit board P using the circuit board inspection apparatus 31, first, the probe moving mechanism 2
The probes 4a and 4b are controlled by the control unit 36.
Then, the probes 4c and 4d are moved to make contact with the respective end points of the conductor pattern to be measured. Next, the constant current source 41 supplies a DC constant current to the conductor pattern via the probes 4a and 4d under the control of the control unit 36, and the voltmeter 42
Measures the voltage between both ends of the conductor pattern detected by the probes 4b and 4c. Next, the control unit 36
Calculating a resistance value between both ends of both conductor patterns based on a current value of a DC current supplied from the constant current source 41 and a voltage measured by the voltmeter 42, and comparing the calculated value with a predetermined threshold value; Thus, the disconnection of the conductor pattern is determined.

[0005]

However, the conventional circuit board inspection apparatus 31 has the following problems. That is, in the conventional circuit board inspection apparatus 31, in order to perform measurement by the four-terminal method at the time of electrical inspection of the circuit board P, the tips of the probes 4a, 4b and the probes 4c, 4d are not brought into contact with each other, and They are juxtaposed at a close distance. However, for example, as shown in FIG. 3A, a case where a conductive foreign matter X such as solder dust adheres between the probes 4a and 4b (or between 4c and 4d), or as shown in FIG. In addition, due to repeated probing, probe 4
When the tips of a and 4b (or 4c and 4d) are bent and come into contact with each other, the resistance component of the foreign matter X and the contact resistance component between the probes 4a and 4b (or 4c and 4d) are measured. It becomes an error. Therefore, since the measurement by the four-terminal method cannot be performed correctly, there arises a problem that the reliability of the disconnection inspection for the conductor pattern is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a circuit board inspection apparatus capable of improving the reliability of a circuit board inspection based on a voltage measured using a contact probe. The main purpose is.

[0007]

According to a first aspect of the present invention, there is provided a circuit board inspection apparatus in which contact-side ends contacting a conductor pattern to be inspected are closely juxtaposed in a non-contact state. The first and second contact probes, the third and fourth contact probes in which the contact-side end portions that come into contact with the conductor pattern approach each other in a non-contact state, and the first and fourth contact probes. A measuring unit for measuring a voltage between the second and third contact probes while a constant current for measurement is supplied to the conductor pattern via the contact probe, and an electric power for the conductor pattern based on the measurement result of the measuring unit. And a control unit for performing a dynamic inspection, wherein the measuring unit supplies a constant current between the two contact probes arranged side by side and supplies a voltage between the two contact probes. The measured, the control unit is characterized by performing the insulation test for both a contact probe based on the voltage measured by the measurement unit.

According to a second aspect of the present invention, in the circuit board inspecting apparatus according to the first aspect, the measuring section supplies an alternating constant current as a constant current.

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 the first and second contact probes and the third and fourth contact probes are inspected. Providing a probe moving mechanism for moving each toward the conductor pattern, the measuring unit,
It is characterized in that a voltage between the two contact probes being moved by the probe moving mechanism is measured, and the control unit performs an insulation test on the two contact probes being moved.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment 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 31 are denoted by the same reference numerals, and redundant description will be omitted.

First, the configuration of the circuit board inspection apparatus 1 according to the present invention will be described with reference to FIGS.

As shown in FIG. 1, the circuit board inspection apparatus 1 includes probe moving mechanisms 2a and 2b, and probes 4a to 4a.
d, a measuring unit 5 and a control unit 6. The probe moving mechanism 2a, 2b controls the probe 4 under the control of the control unit 6.
a, 4b and the probes 4c, 4d are moved toward the conductor pattern to be measured. In this case, as shown in FIG. 3, the probes 4a and 4b are attached to the probe moving mechanism 2a via the probe holder 3, and the probes 4c and 4d are attached to the probe moving mechanism 2b.
Attached through. The probes 4a to 4d
For example, it is constituted by a pin-shaped contact-type metal probe, and constitutes the first to fourth contact probes in the present invention. The probes 4a and 4b (and 4c and 4c)
d) is held by the probe holder 3 in a state where the tip portions are juxtaposed so as not to contact each other and to be located at a close distance as shown in FIG. As shown in FIG. 2, the measuring unit 5 includes, for example, a constant current source 11 that supplies an AC constant current for measurement, a voltmeter 12 that measures a voltage between the probes 4 b and 4 c, and a control unit 6 that controls the voltage. Probe 4a to 4d for constant current source 11 and voltmeter 12
, And switches 13 to 16 for selectively connecting. The control unit 6 includes the probe moving mechanisms 2a and 2b
In addition to the drive control for the current, a calculation process of a resistance value or an impedance value based on the current value of the AC constant current supplied from the constant current source 11 in the measurement unit 5 and the voltage value measured by the voltmeter 12 is performed. Execute.

Next, a method of inspecting the circuit board P by the circuit board inspection apparatus 1 will be described with reference to the drawings.

In the circuit board inspection apparatus 1, prior to the electrical inspection of the circuit board P to be inspected, the insulation state between the probes 4a and 4b and between the probes 4c and 4d is inspected. Specifically, the control unit 6 includes the switches 13 to
By controlling the switching of No. 16, each d contact is connected to each a contact. Thereby, both the constant current source 11 and the voltmeter 12 are connected to the probes 4a and 4b, respectively. Next, the control unit 6 controls the constant current source 11 to supply an AC constant current for measurement and causes the voltmeter 12 to measure the voltage between the probes 4a and 4b. in this case,
Since the two probes 4a and 4b are arranged side by side at a close distance, it can be considered that the capacitance is connected between the two in terms of AC. Therefore, when the insulation state is normal, the impedance between both probes 4a and 4b is
For example, it is in the range of 10 kΩ to several tens kΩ.

For this reason, as shown in FIG. 3A, when the foreign matter X is attached between the probes 4a and 4b, or as shown in FIG. Are in contact with each other, the two probes 4a and 4b are short-circuited, so that the value measured by the voltmeter 12 has a low impedance. Therefore, the control unit 6 calculates the measured value,
Comparison is made with a first threshold value (for example, 5 kΩ) for detecting insulation failure, and when the measured value is lower than the first threshold value, it is determined that insulation failure has occurred between the probes 4a and 4b. Determine.

On the other hand, even if insulation failure does not occur in both probes 4a, 4b, both probes 4a, 4b
The connection cable between the sensor and the measuring unit 5 may be broken. In such a case, it becomes impossible to perform all electrical tests on the circuit board P normally. Therefore, the control unit 6 compares the measured value with a second threshold value (for example, 100 kΩ) for detecting cable disconnection. When a disconnection occurs, the measured value becomes higher than the second threshold value. In such a case, the control unit 6 determines that the connection cable is disconnected.

Next, the control unit 6 includes the switches 13 to 16
, The respective d contacts are respectively connected to the respective c contacts, and the probes 4c and 4d are also inspected for the presence of insulation failure and the presence of cable disconnection in the same manner as the inspection for the probes 4a and 4b. Thereafter, the probes 4a,
When it is determined that the insulation failure or the disconnection of the cable has occurred in the probe 4b or the probes 4c and 4d, the electrical inspection of the circuit board P is finished and the display unit (not shown) is notified of the abnormality.

On the other hand, when it is determined that no insulation failure or cable break has occurred, the control section 6 controls the driving of the probe moving mechanisms 2a and 2b to cause each of the probes 4a to 4d to carry the conductor pattern to be inspected. Move to At the same time, the control unit 6 controls the switches 13 to 16 during the movement of the probes 4a to 4d,
Each d contact is connected to each b contact. This allows
A constant current source 11 is connected to the probes 4a and 4d, and
A voltmeter 12 is connected to the probes 4b and 4c. Next, the control unit 6 drives and controls the probe moving mechanisms 2a and 2b, for example, to bring the probes 4a and 4b into contact with one end of one conductor pattern and to connect the probes 4c and 4d to the other end of the conductor pattern. Make contact.

Subsequently, the control unit 6 measures a resistance value between both end points of the conductor pattern to be inspected according to a four-terminal method.
Next, the control unit 6 determines the resistance value and a predetermined upper and lower threshold value (for example, the upper threshold value is 1Ω and the lower threshold value is 10 mΩ).
When the resistance value is within the range of the upper and lower thresholds, it is determined that the conductor pattern is normal, and when the resistance is out of the range of the upper and lower thresholds, it is determined that an abnormality has occurred. Subsequently, each time the control unit 6 drives and controls the probe moving mechanisms 2a and 2b to move the probes 4a to 4d toward the next conductor pattern to be inspected, the control unit 6 detects the above-described insulation failure and cable disconnection during the movement. The presence / absence is inspected, and thereafter, the inspection of the resistance of the conductor pattern and the inspection of the presence / absence of insulation failure and cable disconnection are repeated. Next, when the electrical inspection of all the conductor patterns is completed, the control unit 6 determines the quality of the circuit board P, and thereby, the circuit board P
The inspection for is completed.

As described above, according to the circuit board inspection apparatus 1, the probe 4a (or 4d) for supplying a constant voltage,
By performing an insulation test with the voltage measurement probe 4b (or 4c) and a cable disconnection test, it is possible to determine in advance whether the measurement conditions are satisfactory. Therefore,
When the resistance value is measured by the four-terminal method, erroneous measurement due to abnormal measurement conditions can be avoided, so that the reliability of circuit board inspection can be improved. Further, by performing an insulation test or the like using the time during which the probes 4a to 4d are moved by the probe moving mechanisms 2a and 2b, the test time required for the insulation test or the like can be substantially ignored. Can be avoided.

The present invention is not limited to the configuration shown in the above-described embodiment of the present invention. For example, in the embodiment of the present invention, an example in which an insulation test or the like is performed using an AC constant current has been described. However, an insulation test or the like can be performed by supplying a DC constant current instead of the AC constant current. However, it is preferable to use an AC constant current in that the disconnection inspection of the connection cable can be performed. Further, in the embodiment of the present invention, an example has been described in which an insulation test or the like and a disconnection test of a conductor pattern are switched by switching control of the switches 13 to 16, but a scanner device or another electrical switching unit is used. Alternatively, a configuration in which the connection between the probes 4a to 4d and the constant current source 11 and the voltmeter 12 is switched may be employed.

Further, in the embodiment of the present invention, before the actual inspection of the conductor pattern is started, and the probe 4a
4 to 4d, the example in which the insulation inspection and the like for both the inspection probes are performed during each movement time has been described. However, the present invention is not limited to this. It can be configured to be performed at any time, such as once a day, once a day, once a week, or at a time specified by an operator. Further, in the embodiment of the present invention, an example has been described in which an abnormality is displayed when an insulation abnormality has occurred between both probes. However, the present invention is not limited to this. ,
It is possible to adopt a configuration in which automatic replacement with a separately prepared spare probe or the like can be performed. In this case, by adopting a configuration in which the probe is automatically replaced, the circuit board inspection apparatus can be unmanned, and the inspection operation can be continuously performed without interrupting the measurement operation. Also,
The inspection content of the circuit board is not limited to the inspection by the four-terminal method and the disconnection inspection, but may be various inspection content obtained by using a contact probe.

[0023]

As described above, according to the circuit board inspection apparatus of the first aspect, the control unit controls the voltage between the first and second contact probes measured by the measurement unit and the second and the second contact probes. By performing an insulation test on both contact probes based on the voltage between the contact probes of No. 4, it is possible to prevent an erroneous test due to insulation failure of the contact probes beforehand, thereby improving the reliability of the circuit board inspection. Can be improved.

Further, according to the circuit board inspection apparatus of the present invention, the measuring section performs an insulation inspection on both contact probes by using an AC constant current, so that in addition to insulation of the contact probes, disconnection of the connection cable. As a result, the reliability of the circuit board inspection can be further improved.

Further, according to the circuit board inspection apparatus of the third aspect, the control unit performs the insulation inspection on the contact probe in the state of being moved, thereby effectively utilizing the moving time of the contact probe. Therefore, it is possible to improve the reliability of the circuit board inspection while avoiding an increase in the inspection time.

[Brief description of the drawings]

FIG. 1 is a circuit board inspection apparatus 1 according to an embodiment of the present invention.
FIG. 3 is a block diagram showing the configuration of FIG.

FIG. 2 is a circuit diagram showing a configuration of a measuring unit 5 in the circuit board inspection device 1.

FIG. 3 is a side view of a constant current supply probe 4a (4d) and a voltage measurement probe 4b (4c).

FIG. 4 is a block diagram showing a configuration of a conventional circuit board inspection device 31.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Circuit board inspection apparatus 2a, 2b Probe moving mechanism 4a-4d Probe 5 Measuring part 6 Control part 11 Constant current source 12 Voltmeter 13-16 Switch P Circuit board

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H05K 3/00 G01R 31/28 K

Claims (3)

[Claims] 1. A first and a second contact probe, wherein contact-side ends contacting a conductor pattern to be inspected are arranged side by side in close proximity to each other in a non-contact state, and contact-side ends contacting the conductor pattern. Third and fourth contact probes arranged side by side in close proximity to each other in a non-contact state, and a state in which a constant current for measurement is supplied to the conductor pattern via the first and fourth contact probes Circuit board inspection, comprising: a measurement unit that measures a voltage between the second and third contact probes; and a control unit that performs an electrical inspection on the conductor pattern based on a measurement result of the measurement unit. The device, wherein the measuring unit measures a voltage between the two contact probes in a state where a constant current is supplied between the two contact probes arranged in parallel. The circuit board inspection device which is characterized in that an insulation test on the two contact probe based on the measured voltage by the measuring unit. 2. The circuit board inspection apparatus according to claim 1, wherein the measuring section supplies an AC constant current as the constant current. 3. A probe moving mechanism for moving the first and second contact probes and the third and fourth contact probes toward a conductor pattern to be inspected, respectively, wherein the measuring unit comprises: A voltage between the two contact probes being moved by a moving mechanism is measured, and the control unit performs the insulation test on the two contact probes being moved. Claim 1 or 2
A circuit board inspection apparatus as described in the above.