JP4949947B2 - Circuit board inspection method and circuit board inspection apparatus - Google Patents

Description

  The present invention relates to a circuit board inspection method and a circuit board inspection apparatus for inspecting a circuit board using a probe unit having a plurality of probes.

As this type of circuit board inspection apparatus, the present applicant has already developed a circuit board inspection apparatus disclosed in Japanese Patent Application Laid-Open No. 2003-57285. This circuit board inspection device has four terminals for the resistance value between one land formed on the back surface of the package board and another land on the surface side of the circuit board connected to the one land through a through hole. A circuit board inspection apparatus for measuring according to a method, wherein two insulated contacts are configured to be able to contact one land, and a conductive material that covers the surface of the circuit board and can be conducted to another land A conductive rubber mat and another probe penetrating in contact with another land while being insulated from the conductive rubber mat. In this circuit board inspection apparatus, a predetermined current is supplied from a constant current source between the conductive rubber mat and one contact of one probe, and the other is penetrated through the conductive rubber mat and brought into contact with another land. The voltage between one contact of one probe and another contact of one probe brought into contact with one land is measured with a voltmeter, and based on the measured voltage and the current value of a predetermined current Measure the resistance value. According to this circuit board inspection apparatus, since a constant current source and a voltmeter can be connected to other lands formed on the surface of the circuit board via a conductive rubber mat and other probes, it can be used on a fine pitch board. On the other hand, the resistance value measurement by the four-terminal method can be performed with high accuracy and at low cost.
Japanese Patent Laid-Open No. 2003-57285 (pages 1, 5, 6 and FIG. 1)

  However, the circuit board inspection apparatus has the following problems to be solved. That is, in this circuit board inspection apparatus, the conductive rubber mat connected to the constant current source and one probe connected to the voltmeter are arranged on the surface side of the circuit board and connected to the constant current source and the voltmeter. The other probe is disposed on the back side of the circuit board. For this reason, the voltage detection path for the voltmeter includes a voltmeter, a probe located on the front side of the circuit board, a land formed on the front side of the circuit board, and a land formed on the back side of the circuit board. This is a wide-area path through the circuit board that returns to the voltmeter via a through-hole to be connected, a land formed on the back side of the circuit board, and a probe located on the back side of the circuit board. The current supply path for the constant current source is also formed on the constant current source, the conductive rubber mat located on the front side of the circuit board, the land formed on the front side of the circuit board, and the land and the back side of the circuit board. This is a wide-area path through the circuit board that returns to the constant current source via the through hole that connects the land, the land formed on the back side of the circuit board, and the probe located on the back side of the circuit board. . Thereby, in this circuit board inspection apparatus, since the current supply path is formed in a wide path, when the constant current from the constant current source is an AC constant current, the constant current flows through the current supply path. Thus, the induced electromotive force is likely to be generated at a large level in the voltage detection path. Therefore, in this circuit board inspection apparatus, this large level of induced electromotive force is superimposed on the voltage generated between both ends of the through-hole by supplying a constant current, so that the voltage generated between both ends of the through-hole As a result, it is difficult to accurately measure the resistance value of the through hole, and it is difficult to further improve the inspection accuracy of the through hole. Yes.

  In addition, when the constant current from the constant current source is a DC constant current, an induced electromotive force is generated at a large level in the voltage detection path in a predetermined period from the start of constant current application. As with constant current, the voltage generated across the through hole cannot be accurately measured with a voltmeter, and as a result, the resistance value of the through hole cannot be accurately measured. As a result, the through hole can be inspected with high accuracy. There is a problem that there is no. In this case, voltage measurement without the influence of induced electromotive force is possible by performing voltage measurement after a predetermined period of time has elapsed since the start of DC constant current application. As a result, there arises a new problem that the inspection speed cannot be increased.

  The present invention has been made to solve such a problem, and a main object of the present invention is to provide a circuit board inspection method capable of improving inspection accuracy. Another main object is to provide a circuit board inspection apparatus capable of executing this circuit board inspection method.

  In order to achieve the above object, a circuit board inspection method according to claim 1, wherein a first probe unit having a plurality of probes is disposed on one surface side of the circuit board, and a second having a plurality of probes. The plurality of probes of the first probe unit are arranged at contact points defined on the plurality of wiring patterns formed on the one surface. Of the probes of the second probe unit are brought into contact with each of the contact points defined on the plurality of wiring patterns formed on the other surface. Two corresponding probes are brought into contact with each other, and the two probes in contact with the respective contact points in the plurality of probes of the second probe unit. One of the pins is short-circuited and defined on the wiring pattern on the one surface side connected to one end side of the via group to be inspected among the plurality of vias formed on the circuit board One of the two probes that are in contact with the first contact point, and one end side of the other via group excluding the via group to be inspected among the plurality of vias. One of the two probes in contact with the second contact point defined on the wiring pattern on one surface side is used as a current supply probe, and the via group to be inspected is used. The other of the two probes that are in contact with the first contact point by supplying a measurement current, and other via groups to be inspected among the contact points on the other surface side Connect with end The other of the two probes that are in contact with the third contact point defined on the wiring pattern on the other surface side is used as a voltage detection probe, and the first contact point and A point-to-point voltage generated between the third contact points is measured, and a resistance of the via group to be inspected is measured by a four-terminal method based on the measurement current and the point-to-point voltage, and based on the resistance. To inspect the via group. Here, the via group in the present specification is composed of one or a plurality of vias connected in series, penetrating the front and back of the circuit board, and one end thereof is formed on one surface of the circuit board. It is connected to the wiring pattern and has the other end connected to another wiring pattern formed on the other surface of the circuit board.

  According to a second aspect of the present invention, the circuit board inspection apparatus includes a plurality of probes and is provided on one surface side of the circuit board and defined on the plurality of wiring patterns formed on the one surface. A first probe unit configured to be able to simultaneously contact two corresponding probes of the plurality of probes to the contact point, and a plurality of probes, and disposed on the other surface side of the circuit board. Two corresponding probes of the plurality of probes can be simultaneously contacted with each contact point defined on the plurality of wiring patterns formed on the other surface, and each of the plurality of probes A second probe unit having a short-circuit wiring for short-circuiting one of the two probes in contact with the contact point, and a current supply unit for outputting a measurement current A voltage measurement unit; one of the two probes connected to any one of the plurality of contact points defined on the one surface side and the plurality of contact points A first switching unit that selects one of the two probes connected to any one other contact point and electrically connects to the current supply unit, and is defined on the one surface side Any one of the plurality of contact points defined on the other side and the other surface side of the two probes connected to any one of the plurality of contact points A second switching unit that selects and electrically connects the other of the two probes connected to one contact point to the voltage measurement unit, and a processing unit, and the processing unit includes: 1 and 2 probe units A plurality of vias formed on the circuit board by controlling the first switching unit in a state where the plurality of probes are brought into contact with the corresponding contact points. One of the two probes in contact with the first contact point defined on the wiring pattern on the one surface side connected to one end side of the via group, and the circuit board A second contact point defined on the wiring pattern on the one surface side connected to one end side of another via group excluding the via group to be inspected among the plurality of formed vias. One of the two probes that are in contact with each other is connected to the current supply unit as a current supply probe, and the second switching unit is controlled to contact the first contact point. 2 The two probes in contact with the third contact point defined on the wiring pattern on the other surface side connected to the other of the probes and the other end side of the via group to be inspected The other of the probes is connected to the voltage measurement unit as a voltage detection probe, and the current supply unit is controlled to the via group, the short-circuit wiring, and the other via group to be inspected. The measurement current is supplied via a current supply probe, and the voltage measurement unit is controlled to measure a voltage between points generated between the first contact point and the third contact point, and the measurement current and Based on the voltage between the points, the resistance of the via group to be inspected is measured by a four-terminal method, and the via group is inspected based on the resistance.

  In the circuit board inspection method according to claim 1 and the circuit board inspection apparatus according to claim 2, when the via group of the circuit board is to be inspected, the first probe unit including a plurality of probes is attached to one of the circuit boards. The second probe unit having a plurality of probes is disposed on the other surface side of the circuit board, and each defined on the plurality of wiring patterns formed on the one surface is disposed on the surface side. Two corresponding probes of the plurality of probes of the first probe unit are brought into contact with the contact point, respectively, and the second contact point is defined on each of the plurality of wiring patterns formed on the other surface. Two corresponding probes of the plurality of probes of the probe unit are brought into contact with each other, and contacted with each contact point in the plurality of probes of the second probe unit. One of the two probes is short-circuited together and specified on the wiring pattern on one surface side connected to one end side of the via group to be inspected among the plurality of vias formed on the circuit board One surface connected to one end side of the other via group excluding the via group to be inspected out of the plurality of vias and one of the two probes contacting the first contact point A measurement current is supplied to the via group to be inspected by using one of the two probes in contact with the second contact point defined on the wiring pattern on the side as a current supply probe, Wiring on the other surface side connected to the other end side of the via group to be inspected among the other contact points on the other surface side of the two probes that are in contact with one contact point and the other surface side The number specified on the pattern Measuring the inter-point voltage generated between the first contact point and the third contact point by using the other of the two probes in contact with the contact point as a voltage detection probe. The resistance (resistance value) of the via group to be inspected is measured by the four-terminal method based on the voltage between points, and the via group is inspected based on the resistance (resistance value).

  Therefore, according to this circuit board inspection method and this circuit board inspection apparatus, when a constant current (AC constant current or DC constant current) is supplied as a measurement current, the current path through which the measurement current flows is as described above. Is formed only on one side (in this example, one side), so the two probes that make up the current path are closer to each other compared to the arrangement on both sides of the circuit board And one of the two probes becomes a return path for the measurement current flowing to the other and the direction of the measurement current flowing to both probes is reversed. The magnetic flux generated in the two current probes and the magnetic flux generated on the other side of the two probes cancel each other, so that the amount of the magnetic flux generated in the entire current path through which the measurement current flows can be greatly reduced.Therefore, since the induced electromotive force generated in the voltage detection path due to the generation of magnetic flux in this current path can be greatly weakened, the voltage generated by the voltage measuring unit in the via group to be inspected (between points) As a result, the processing unit can measure the resistance value of the via group to be inspected with high accuracy based on the current value and the voltage value of the measurement current. The inspection accuracy of the inspection object to be performed can be sufficiently improved. In addition, when a DC constant current is supplied as a measurement current, the induced electromotive force disappears after a predetermined period from the start of application. The generated voltage can be accurately measured with a voltmeter, and through holes can be inspected with high accuracy. According to this circuit board inspection method and this circuit board inspection apparatus, a DC constant current is used as a measurement current. Even when the current is supplied, the through hole can be inspected with high accuracy immediately after the measurement current is supplied.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to the accompanying drawings, a best mode of a circuit board inspection method and a circuit board inspection apparatus that implements the circuit board inspection method according to the present invention will be described below.

  As shown in FIG. 1, the circuit board inspection apparatus 1 includes a pair of probe units 2 and 3, a current supply unit 4, a voltage measurement unit 5, a first switching unit 6, a second switching unit 7, a processing unit 8, and a storage unit. 9 and the output unit 10, and a plurality of wiring patterns (for example, wiring patterns 21, 22, 23, 25, 26) and a plurality of vias (for example, vias 31, 32, 33, 34) formed on the circuit board 11. , 35, 36, 37) via groups to be inspected (via groups including vias 31, 32, 33, via groups including vias 34, 35, 36, and via groups including vias 37, 35, 36) ) Can be executed. In this example, the via group is composed of a plurality of (three as an example) vias connected in series, but the number is not limited, and one, two, or four or more It may be composed of vias.

  Further, a contact point for bringing a probe, which will be described later, into contact with each of the wiring patterns 21 to 23, 25, and 26 of the circuit board 11 is previously defined at a predetermined position. Specifically, wiring patterns 21 to 23 are formed on one surface (the upper surface in the figure) of the circuit board 11, and a via group including the vias 31, 32, and 33 (hereinafter referred to as the via 31). The contact point TP1 used when inspecting the group of vias 31, 32, and 33 is defined in the wiring pattern 21 connected to one end side of each of the vias 31, 32, and 33). In addition, the wiring pattern 22 connected to one end side of a via group including the vias 34, 35, and 36 (hereinafter also referred to as a group of vias 34, 35, and 36) is inspected. The contact point TP2 used at the time is defined, and the via 37 is connected to the wiring pattern 23 connected to one end of a via group including the vias 37, 35, and 36 (hereinafter also referred to as a group of vias 37, 35, and 36). , 35, and 36, the contact point TP3 used when inspecting the group is defined. On the other hand, wiring patterns 25 and 26 are formed on the other surface (the lower surface in the figure) of the circuit board 11, and the wiring pattern in contact with the other end side of the group of the vias 31, 32, and 33 among them. 25 defines a contact point TP6 that is used when a group of vias 31, 32, and 33 is inspected. The wiring pattern 26 connected to the other end side of the group of vias 34, 35, 36 and the group of vias 37, 35, 36 includes the group of vias 34, 35, 36 and the vias 37, 35, 36. A contact point TP7 is defined that is used when inspecting a group. Hereinafter, when the contact points TP1 to TP7 are not particularly distinguished, they are also referred to as “contact points TP”.

  The probe unit 2 corresponds to the first probe unit in the present invention, and includes a plurality (6 in this example) of probes 2a to 2f, and one surface side of the circuit board 11 placed at the inspection position. (Upper side in FIG. 1) In the inspection position (the position in FIG. 1), the circuit board 11 is placed at the inspection position (the position shown in FIG. 1), and the retracted position (not shown) and the contact position (where the circuit board 11 is removed from the inspection position) (Position shown in FIG. 1) is movable by a moving mechanism (not shown). In addition, when the probe unit 2 is moved to the contact position, the probe unit 2 is connected to a plurality of contact points TP1 to TP3 defined on the wiring patterns 21, 22, and 23 formed on the circuit board 11 among the probes 2a to 2f. The two corresponding probes are in contact with each other. In this example, in the probe unit 2, the pair of probes 2a and 2b are in contact with the contact point TP1, the pair of probes 2c and 2d are in contact with the contact point TP2, and the pair of probes 2e and 2f are in contact with the contact point TP3. It is configured as follows.

  The probe unit 3 corresponds to the second probe unit in the present invention, and includes a plurality of (in this example, four as an example) probes 3a to 3d, and the other surface side of the circuit board 11 placed at the inspection position. (On the lower side in FIG. 1), a contact position (not shown) that allows the circuit board 11 to be placed at the inspection position (position of FIG. 1) and the circuit board 11 to be taken out from the inspection position; It is configured to be movable between the positions (positions shown in FIG. 1) by the aforementioned moving mechanism. Further, when the probe unit 3 is moved to the contact position, the probe unit 3 corresponds to a plurality of contact points TP6 and TP7 defined on the wiring patterns 25 and 26 of the circuit board 11 and corresponding two of the probes 3a to 3d. The probes are in contact with each other. In this example, the probe unit 3 is configured such that the pair of probes 3a and 3b are in contact with the contact point TP6 and the pair of probes 3c and 3d are in contact with the contact point TP7. The probe unit 3 includes one of the two probes 3a and 3b (probe 3a) connected to the contact point TP6 and one of the two probes 3c and 3d connected to the contact point TP7. Short-circuit wiring 3k that short-circuits (probe 3c) is provided. When the probe unit 3 includes three or more pairs of probes that contact a common contact point such as the probes 3a and 3b and the probes 3c and 3d, of the two probes included in all the sets. Are short-circuited (connected) to each other via the short-circuit wiring 3k.

  The current supply unit 4 is controlled by the processing unit 8 to output a measurement current I1 (DC constant current (current value Ix1 as an example)) from a pair of output terminals (not shown) and supply the measurement current I1 to the first switching unit 6. To do. The voltage measuring unit 5 is controlled by the processing unit 8 to input the voltage V1 output from the second switching unit 7 through a pair of input terminals, and measures and outputs the voltage value Vx1.

  The first switching unit 6 is configured as a scanner by combining a plurality of changeover switches. The first switching unit 6 is connected to one of the two probes 2 a and 2 b (probe 2 a) brought into contact with the contact point TP <b> 1 defined on one surface side of the circuit board 11 via the cable 12. Has been. In addition, the first switching unit 6 is connected to one of the probes 2c and 2d (probe 2c) that is brought into contact with another contact point TP2 defined on one surface side of the circuit board 11 via the other cable 12. In addition to being connected, one of the probes 2e and 2f (probe 2e) brought into contact with another contact point TP3 is also connected via another cable 12. Further, the first switching unit 6 is controlled by the processing unit 8, and any two of the probes 2 a, 2 c, 2 e are used as current supply probes, respectively, and current supply units are connected via corresponding cables 12. 4 to a pair of output terminals.

  The second switching unit 7 is configured as a scanner by combining a plurality of changeover switches. Further, the second switching unit 7 is connected to the other of the two probes 2 a and 2 b (probe 2 b) brought into contact with the contact point TP <b> 1 defined on one surface side of the circuit board 11 through the cable 13. Has been. The second switching unit 7 is connected to the other of the probes 2c and 2d (probe 2d) that is brought into contact with the other contact point TP2 defined on one surface side of the circuit board 11 via the other cable 13. The other of the probes 2e and 2f (probe 2f) brought into contact with the other contact point TP3 is also connected via another cable 13 while being connected. Further, the second switching unit 7 is connected to the other of the probes 3a and 3b (probe 3b) to be brought into contact with the contact point TP6 defined on the other surface side of the circuit board 11 via the cable 14. The other of the probes 3c and 3d (probe 3d) brought into contact with the other contact point TP7 is also connected via another cable 14. The second switching unit 7 is controlled by the processing unit 8 to detect the voltage of any one of the probes 2b, 2d, and 2f and any one of the probes 3b and 3d, respectively. The probe is connected to a pair of input terminals of the voltage measuring unit 5 through corresponding cables 13 and 14.

  The processing unit 8 includes a CPU and operates according to an operation program stored in advance in the storage unit 9 to execute a circuit board inspection process for the circuit board 11 placed at the inspection position. Control is performed for the moving mechanism that moves the probe units 2 and 3, the current supply unit 4, the voltage measurement unit 5, and the switching units 6 and 7. The storage unit 9 is composed of a ROM and a RAM. When the storage unit 9 inspects the operation program for the processing unit 8, information about the via group formed on the circuit board 11 and to be inspected, and the via group to be inspected. A list of probes for each test object used to measure each of their resistance values using the four probe method, the use of the probe (whether used for current supply probes or voltage detection probes), and the test object A reference value (reference resistance value Rref) for determining whether the via group is good or bad is stored in advance. The storage unit 9 stores a current value Ix1 of the measurement current I1. The output unit 10 is configured by a display device as an example, and displays the result of the inspection process output from the processing unit 8.

  Next, the operation of the circuit board inspection apparatus 1 will be described with reference to FIGS. It is assumed that the circuit board 11 is previously placed at the inspection position.

  In this state, when the power of the circuit board inspection apparatus 1 is turned on, in the circuit board inspection apparatus 1, the processing unit 8 operates according to the operation program and starts the circuit board inspection process. In the circuit board inspection process, the processing unit 8 first controls the moving mechanism to move the probe units 2 and 3 from the retracted position to the contact position (step 51). Thereby, in the probe unit 2, the pair of probes 2a and 2b are in contact with the contact point TP1, the pair of probes 2c and 2d are in contact with the contact point TP2, and the pair of probes 2e and 2f are in contact with the contact point TP3. It becomes. In the probe unit 3, the pair of probes 3a and 3b are in contact with the contact point TP6, and the pair of probes 3c and 3d are in contact with the contact point TP7.

  Next, the processing unit 8 controls the switching unit 7 in this state to connect the current supply unit 4 and the voltage measurement unit 5 to one of the via groups to be inspected first (step 52). ). In this case, the processing unit 8 reads out one of the via groups to be inspected from the storage unit 9, and obtains information on the probe used when inspecting the one inspection target and the use of the probe. Read from the storage unit 9. Further, the processing unit 8 controls the switching state of the switching units 6 and 7 based on the read information, so that two of the probes 2a, 2c, and 2e serving as current supply probes are connected to the cable 12 and the second one. 1 is connected to each output terminal of the current supply unit 4 through the switching unit 6, and one of the probes 2 b, 2 d, 2 f serving as a voltage detection probe is voltage-measured through the cable 13 and the second switching unit 7. One of the probes 3b and 3d is connected to one input terminal of the unit 5 and the other voltage detection probe is connected to the other input terminal of the voltage measuring unit 5 via the cable 14 and the second switching unit 7. Connecting.

  As an example, when the processing unit 8 reads out a group of vias 31, 32, and 33 (a set of vias connected in series by the inner layer wiring pattern 28) from the storage unit 9 as the first inspection target, Further information from the storage unit 9 is read out from the storage unit 9 and the probe used when inspecting the probe. In this case, the processing unit 8 uses the contact point TP1 (first contact in the present invention) defined on the wiring pattern 21 connected to one end side of the group of the vias 31, 32, and 33 as information on the probe to be used. One of the two probes 2a and 2b in contact with the point (probe 2a in this example), and another via group (this example) excluding the inspection target among a plurality of vias formed on the circuit board 11 As an example, the two contact points TP2 (second contact point in the present invention) defined on the wiring pattern 22 connected to one end side of the vias 34, 35, and 36) are contacted. One of the probes 2c and 2d (probe 2c in this example), the other of the probes 2a and 2b in contact with the contact point TP1 (probe 2b in this example), and A contact point TP6 (third contact in the present invention) defined on the wiring pattern 25 connected to the other end side (the other surface side of the circuit board 11) in the group of the vias 31, 32, and 33 to be inspected. Information on the other of the two probes 3a and 3b in contact with the point (probe 3b in this example) is read.

  Further, the processing unit 8 reads out information on the use of the probes as the current supply probes and the information on the use of the two probes 2b and 3b as voltage detection probes. Further, the processing unit 8 controls the first switching unit 6 based on the read information about the probe to be used and its use, and the probes 2 a and 2 c are connected to the current supply unit via the cable 12 and the first switching unit 6. 4, the second switching unit 7 is controlled, and the probes 2 b and 3 b are connected to the voltage measuring unit 5 through the cables 13 and 14 and the second switching unit 7.

  Subsequently, the processing unit 8 performs a measurement process of the resistance value R for the group of the vias 31, 32, and 33 to be inspected (Step 53). In this measurement process, the processing unit 8 first controls the current supply unit 4 to start output of the measurement current I1, and controls the voltage measurement unit 5 to start measurement of the voltage V1. Thus, the measurement current I1 output from the current supply unit 4 passes through the first switching unit 6, the single cable 12, the probe 2a, the wiring pattern 21, the group of the vias 31, 32, and 33, and the wiring pattern 25. Then, after reaching the contact point TP6, it flows into the group of other vias 36, 35, and 34 via the probe 3a and the probe 3c connected to each other by the short-circuit wiring 3k in the probe unit 3, and the wiring pattern 22, the probe 2 c, another cable 12, and the first switching unit 6, and the current path returning to the current supply unit 4. In addition, due to the measurement current I1 flowing through the group of vias 31, 32, 33, a voltage (main) is applied between the contact points TP1, TP6 defined on each end side of the group of vias 31, 32, 33. The point-to-point voltage (V1) in the invention is generated. The voltage measuring unit 5 uses this voltage V1 as a probe connected via the second switching unit 7 and one cable 13 and a probe connected via the second switching unit 7 and one cable 14. Input via 3b.

  At this time, due to the measurement current I1 flowing through the current path, the second switching unit 7, the one cable 13, the probe 2b, the second switching unit 7, the one cable 14, and the probe 3b are included. An induced electromotive force is generated at a large level in a predetermined period from the start of supply (application) of the measurement current I1 to the configured voltage detection path. In this case, in this example, since the current path through which the measurement current I1 flows is formed only on one side (in this example, one side) of the circuit board 11 as described above, the distance is long. Two paths in the current path that will greatly affect the generation of the induced electromotive force, that is, a first path formed by the first switching unit 6, one cable 12, and the probe 2a, and the first switching unit 6 The other cable 12 and the second path formed by the probe 2c are arranged close to each other. The second path is a return path for the measurement current I1 with respect to the first path, and the measurement current I1 flows in the opposite direction through both paths. As a result, the magnetic flux generated in the second path acts so as to cancel the magnetic flux generated in the first path, and the amount of magnetic flux generated in the entire current path through which the measurement current I1 flows is greatly reduced. Therefore, in this circuit board inspection apparatus 1, since the induced electromotive force generated in the voltage detection path due to the measurement current I1 flowing in the current path is significantly weakened, the voltage V1 input to the voltage measurement unit 5 is reduced. The waveform is a waveform that is extremely less affected by the induced electromotive force due to the flow of the measurement current I1.

  Next, the voltage measurement unit 5 measures the voltage value Vx1 of the input voltage V1 and outputs it to the processing unit 8 immediately after the supply (application) of the measurement current I1 is started. Subsequently, the processing unit 8 stores the input voltage value Vx1 in the storage unit 9, and also divides the voltage value Vx1 by the current value Ix1 read from the storage unit 9, whereby the vias 31, 32, The resistance value R of the 33 groups is calculated and stored in the storage unit 9. Thereby, the measurement process of the resistance value R is completed.

  Next, the processing unit 8 executes an inspection process (step 54). In this inspection process, the processing unit 8 reads the resistance value R of the group of vias 31, 32, and 33 calculated in the above-described measurement process and the reference resistance value Rref of the group of vias 31, 32, and 33, and By comparing the two, when the resistance value R is equal to or less than the reference resistance value Rref, it is determined that the group of vias 31, 32, 33 is normal, and when the resistance value R exceeds the reference resistance value Rref, it is determined that the group is abnormal. To do. Further, the processing unit 8 stores the inspection result in the storage unit 9 in association with the information (identification information) of the inspection target (group of vias 31, 32, and 33). Thereby, the inspection process for one inspection object is completed.

  Thereafter, the processing unit 8 repeatedly executes the above steps 52 to 54 while determining whether or not there is an uninspected inspection object among the inspection objects stored in the storage unit 9 (step 55). The inspection is performed for all via groups that are the inspection target. In step 52, when the inspection target is a group of vias 34, 35, and 36, there are a group of vias 31, 32, and 33 and a group of vias 37, 35, and 36 as other via groups. Since the group of vias 37, 35, and 36 partially overlaps the group of vias 34, 35, and 36, the group of vias 31, 32, and 33 is used as another via group in the return path of the measurement current I1.

  Next, after the inspection for all via groups is completed, the processing unit 8 reads out the inspection results for all vias from the storage unit 9 and displays them on the output unit 10 (step 56). Is operated to move the probe units 2 and 3 from the contact position to the retracted position (step 57). Thereby, the circuit board inspection process is completed.

  Thus, in this circuit board inspection method and the circuit board inspection apparatus 1 that implements this circuit board inspection method, when the via group of the circuit board 11 is to be inspected, the probe unit 2 having a plurality of probes 2a to 2f. Is arranged on one surface side of the circuit board 11 and the probe unit 3 having a plurality of probes 3a to 3d is arranged on the other surface side of the circuit board 11 to form a plurality of elements formed on one surface. The two corresponding probes of the plurality of probes 2a to 2f are brought into contact with the contact points TP1 to TP3 defined on the wiring patterns 21 to 23, respectively, and a plurality of wiring patterns formed on the other surface Two corresponding probes of the plurality of probes 3a to 3d are brought into contact with the contact points TP6 and TP7 defined on 25 and 26, respectively. One of the two probes that are in contact with the contact points TP6 and TP7 in the lobes 3a to 3d is short-circuited, and the inspection target is selected from the plurality of vias formed on the circuit board 11. One of the two probes in contact with the contact point TP (first contact point) defined on the wiring pattern on the one surface side connected to one end side of the via group, and a plurality of vias Two in contact with the contact point TP (second contact point) defined on the wiring pattern on one surface side connected to one end side of the other via group excluding the via group to be inspected One of the probes is used as a current supply probe to supply a measurement current I1 to a group of vias to be inspected, and are in contact with a contact point TP (first contact point). The contact point TP defined on the wiring pattern on the other surface side connected to the other end side of the via group to be inspected among the other contact points TP on the other side of the lobes and the other surface side (first Between the contact point TP (first contact point) and the contact point TP (third contact point) using the other of the two probes in contact with each other as a voltage detection probe. The generated point-to-point voltage V1 is measured, and the resistance (resistance value) R of the via group to be inspected is measured by the four-terminal method based on the measured current I1 and the point-to-point voltage V1, and based on the resistance (resistance value) R. The via group is inspected.

  Therefore, according to this circuit board inspection method and this circuit board inspection apparatus 1, when a DC constant current is supplied as measurement current I1 (especially when a DC constant current that rises in steps) is supplied, measurement current I1 flows. Since the current path is formed only on one side (in this example, one side) of the circuit board 11 as described above, the two probes constituting the current path are arranged on both sides of the circuit board 11. And the direction of the measurement current I1 flowing in both probes becomes a return path of the measurement current I1 flowing in one of the two probes to the other. As a result, the magnetic flux generated in one of the two probes and the cable 12 (or cable 13) connected thereto and the other of the two probes and the connection thereof. Acts as the magnetic flux generated in the cable 13 (or cables 12) cancel each other to be the amount of the magnetic flux generated across a current path measurement current I1 flows can be greatly reduced. Therefore, since the induced electromotive force generated in the voltage detection path due to the generation of magnetic flux in the current path can be greatly reduced, the voltage V1 generated in the via group to be inspected by the voltage measuring unit 5 can be reduced. As a result of measuring the voltage value Vx1 with high accuracy, the processing unit (CPU) 8 can measure the resistance value R of the via group to be inspected with high accuracy based on the current value Ix1 and the voltage value Vx1 of the measurement current I1. This makes it possible to sufficiently improve the inspection accuracy of the inspection object to be performed based on the resistance value R.

  Further, according to the circuit board inspection method and the circuit board inspection apparatus 1, even when the measurement current I1 is a DC constant current, the resistance immediately after the start of supply (application) of the measurement current I1 without waiting for the elapse of a predetermined period. Since the inspection for the inspection object based on the value R can be performed, the inspection speed can be increased.

  Note that the present invention is not limited to the embodiment of the invention described above, and can be modified as appropriate. For example, in the above-described embodiment, a configuration in which the first switching unit 6 for the current supply unit 4 and the second switching unit 7 for the voltage measurement unit 5 are separated is employed. The two switching units 7 can be collectively configured as one switching unit. In the embodiment of the present invention described above, a multilayer substrate is taken as an example of the circuit board 11, and a plurality of vias for connecting a wiring pattern formed on one surface to a wiring pattern formed on the other surface For a substrate in which a wiring pattern formed on one surface and a wiring pattern formed on the other surface are connected by a single through hole, such as a double-sided substrate, Of course, the present invention can be applied to this one through hole as a via group to be tested. Moreover, although the example in which the current supply unit 4 supplies a DC constant current as the measurement current I1 has been described, it is needless to say that the present invention can be applied to a configuration that supplies an AC constant current. Further, the configuration in which the measurement current supply unit 4 supplies (applies) a DC constant current as the measurement current I1 has been described above, but the configuration in which the measurement current supply unit 4 supplies (applies) an AC constant current as the measurement current I1 is adopted. You can also.

1 is a configuration diagram of a circuit board inspection device 1. FIG. 3 is a flowchart for explaining the operation of the circuit board inspection apparatus 1;

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Circuit board inspection apparatus 2, 3 Probe unit 2a-2f, 3a-3d Probe 3k Short circuit wiring 4 Current supply part 5 Voltage measurement part 6 1st switching part 7 2nd switching part 8 Processing part 11 Circuit board 21-23, 25 , 26 Wiring pattern 31 to 37 Via I1 Measurement current TP1, TP2, TP3, TP6, TP7 Contact point V1 Voltage

Claims (2)

A first probe unit including a plurality of probes is disposed on one surface side of the circuit board, and a second probe unit including a plurality of probes is disposed on the other surface side of the circuit board. Two corresponding probes of the plurality of probes of the first probe unit are brought into contact with the contact points defined on the plurality of wiring patterns formed on the one surface, respectively, and the other Two corresponding probes of the plurality of probes of the second probe unit are brought into contact with the contact points defined on the plurality of wiring patterns formed on the surface, respectively,
Shorting one of the two probes in contact with the contact points of the plurality of probes of the second probe unit;
It is in contact with a first contact point defined on the wiring pattern on the one surface side connected to one end side of a via group to be inspected among a plurality of vias formed on the circuit board. On one of the two probes and on the wiring pattern on the one surface side connected to one end side of the other via group excluding the via group to be inspected among the plurality of vias Supplying a measurement current to the via group to be inspected by using one of the two probes in contact with the defined second contact point as a current supply probe,
The other of the two probes that are in contact with the first contact point, and the other end side of the via group to be inspected among the contact points on the other surface side. Using the other of the two probes in contact with the third contact point defined on the wiring pattern on the other surface side as a voltage detection probe, the first contact point and the Measure the voltage between points generated between the third contact points,
A circuit board inspection method for measuring a resistance of the via group to be inspected based on the measurement current and the voltage between points by a four-terminal method and inspecting the via group based on the resistance. A plurality of probes are provided, and each of the contact points defined on the plurality of wiring patterns formed on the one surface side of the circuit board and corresponding to the two contact points of the plurality of probes is provided. A first probe unit configured to be able to contact two probes simultaneously;
A plurality of probes are provided, and two contact points corresponding to the contact points defined on the plurality of wiring patterns formed on the other surface side of the circuit board and corresponding to the other two of the plurality of probes are provided. A second probe unit having a short-circuit wiring configured to short-circuit one of the two probes that are configured to be capable of simultaneously contacting the two probes and are in contact with the contact points of the plurality of probes;
A current supply for outputting the measurement current;
A voltage measurement unit;
One of the two probes connected to any one of the plurality of contact points defined on the one surface side and any other one of the plurality of contact points A first switching unit that selects and electrically connects one of the two probes connected to one contact point to the current supply unit;
The plurality of contacts defined on the other surface and the other of the two probes connected to any one of the plurality of contact points defined on the one surface side A second switching unit that selects and electrically connects the other of the two probes connected to any one contact point of the points to the voltage measurement unit;
A processing unit,
The processing unit moves the first and second probe units to bring the plurality of probes into contact with the corresponding contact points, and in that state, controls the first switching unit to control the circuit board. The two of the plurality of vias that are in contact with the first contact point defined on the wiring pattern on the one surface side connected to one end side of the via group to be inspected The wiring on the one surface side connected to one end side of the other via group excluding the via group to be inspected among the plurality of vias formed on the circuit board One of the two probes in contact with the second contact point defined on the pattern is connected to the current supply unit as a current supply probe, and the second switching unit is controlled. Defined on the wiring pattern on the other surface side connected to the other of the two probes in contact with the first contact point and the other end side of the via group to be inspected. The other of the two probes that are in contact with the third contact point is connected to the voltage measurement unit as a voltage detection probe, and the current supply unit is controlled to be the inspection target. The measurement current is supplied to the group, the short-circuit wiring, and the other via group via the current supply probe, and the voltage measurement unit is controlled to control between the first contact point and the third contact point. And measuring the resistance of the via group to be inspected based on the measured current and the voltage between the points by the four-terminal method. Circuit board inspection apparatus for inspecting the via group Te.

Images