JP2013019742A - Circuit board inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a clearance between movable arms to be more widened when performing measurement by a four-terminal pair method by using an X-Y type circuit board inspection device.SOLUTION: For performing measurement by a four-terminal pair method, coaxial cables C1 to C4 are used in electrical wirings from current probes P1, P2 and voltage probes P3, P4 to a measuring section 20, and external conductors S of the coaxial cables C1 to C4 are mutually connected via conductive means 70. The coaxial cables C1 to C4 are held as a bundled state by coaxial cable holding means 50 supported substantially at the intermediate position between movable arms 31, 32 via expansion means 60 of pantograph structure expanded/contracted following the motion of the movable arms 31, 32 in X-Y directions. Respective internal conductors IL of the coaxial cables C1 to C4 are connected to the corresponding probes P1 to P4 respectively, via electrical relaying means 80 respectively, each of the electrical relaying means 80 consisting of a deformable leaf spring 81 for example.

Description

  The present invention is a circuit board inspection apparatus called an XY type (or flying type) in which a probe (conductive contact pin) used for circuit board inspection is supported by a movable arm movable in a predetermined direction. The present invention relates to a technique for increasing the degree of freedom of movement of the movable arm when performing measurement by the method.

  There is a four-terminal method as one of methods for measuring the impedance of conductor patterns, mounted parts, elements, etc. (hereinafter referred to as “samples to be measured”) present on a circuit board.

  In the four-terminal method, as shown in the schematic diagram of FIG. 8, as a basic configuration, a measurement signal source 1 that generates a measurement signal, a voltmeter 2 as voltage detection means, and an ammeter as current detection means 3.

  As probes, two current probes P1 and P2 (P1 is on the high potential Hc side and P2 is on the low potential Lc side) included in the measurement current path that flows from the measurement signal source 1 to the measurement sample DUT, and the measurement target Four probes of two voltage probes P3 and P4 (P3 is on the high potential Hp side and P2 is on the low potential Lp side) included in the voltage detection path of the sample DUT are used.

  Although these probes are not structurally different, in the present specification, for convenience of explanation, the current system side is referred to as a current probe, and the voltage system side is referred to as a voltage probe.

  In measurement, for example, a constant current is passed from the measurement signal source 1 to the sample DUT to be measured via the current probes P1 and P2, and the voltage generated at both ends of the sample DUT by this is applied to the voltage via the voltage probes P3 and P4. The impedance Z of the sample DUT to be measured is measured based on the current value obtained by the ammeter 3 and the voltage value obtained by the voltmeter 2.

  According to this four-terminal method, the influence of the wiring resistance of the electrical wiring (lead wire) of the measurement system and the contact resistance with the sample to be measured can be almost eliminated, but the magnetic flux generated by the current flowing through the measurement current path is If the voltage detection path is crossed, an error occurs in the detection voltage, and this error is included in the impedance measurement value.

  This phenomenon becomes a problem particularly during high-frequency measurement in which measurement is performed with a high-frequency measurement current. Even if a coaxial cable (shielded wire) is used for the electrical wiring of the measurement system, there is an effect of electrostatic shielding, but it is not effective for electromagnetic induction as described above.

  This problem due to electromagnetic induction can be solved by the four-terminal pair method. For example, Patent Document 1 is a document relating to the four-terminal pair method, and FIG. 9 schematically shows a measurement state by the four-terminal pair method, which will be described.

  Referring to FIG. 9, in the case of the four-terminal pair method, coaxial cables C1 and C2 are used as the electric wires for current probes P1 and P2, and similarly, coaxial cables C3 and C4 are used for the electric wires of voltage probes P3 and P4. Use. Then, all the outer conductors (shield covered wires) S of the respective coaxial cables C1 to C4 are connected and short-circuited by the lead wires 5 in the vicinity of the base ends of the respective probes.

  The operation will be described. In the four-terminal pair method, an automatic balanced bridge method using the voltage probe P4 on the low potential side as a virtual ground is applied, and the measurement voltage V is applied to the measured sample DUT from the measurement signal source 1 via the Hc line. (This applied voltage is the same as that of the Hp line), a measurement current of V / Z flows through the sample DUT to be measured. This measurement current passes through the ammeter 3 and flows through the outer conductor in the opposite direction and returns to the measurement signal source 1 (see the arrow indicating the current flow direction in FIG. 9).

  At this time, on the opposite side of the sample DUT to be measured, the feedback control circuit FC operates so that Lp becomes Lc (= GND). Therefore, since the same voltage is applied to the sample DUT to be measured at both ends of the voltmeter 2, the value indicated by the voltmeter 2 is the same as the voltage across the sample DUT to be measured.

  Thus, according to the four-terminal pair method, the forward and backward paths of the measurement current are overlapped in the measurement current path, so that the influence of the magnetic flux generated by the measurement current (while maintaining the advantages of the four-terminal method ( Electromagnetic induction) can be reduced.

  Note that all of the outer conductors S of the coaxial cables C1 to C4 are connected by the lead wire 5 because the potentials of the Hp and Lp outer conductors S involved in measuring the voltage are as follows. For example, an undefined state is not preferable.

  By the way, the XY type circuit board device includes at least two movable arms that can move in a predetermined direction (X, Y, and Z directions) on the circuit board, as described in Patent Document 2, for example. A probe is supported on each movable arm, and each sample is measured on the circuit board by moving each movable arm according to a preset inspection program.

  When performing measurement by the four-terminal pair method with an XY type circuit board device, for example, one movable arm is provided with a high potential side current probe P1 and a voltage probe P3, and the other movable arm is provided with a low potential side. A current probe P2 and a voltage probe P4 are provided, and a lead wire 5 for connecting an external conductor is stretched between these movable arms.

  For this reason, the range in which each movable arm can move is limited to the wiring length of the lead wire 5. For example, when the pattern pitch changes and the distance between probing points is longer than the wiring length of the lead wire 5, it is not possible to cope. , Etc.

  In addition, it is not preferable to handle the high frequency to increase the wiring length of the lead wire for connecting the outer conductor spanned between the movable arms, and although it is an extreme example, the interval between the movable arms is reduced. In this case, there is a possibility that the lead wire hangs down on the circuit board to be inspected and is dragged, which is generally not a preferable measure.

Japanese Patent Laid-Open No. 2-122274 JP 2002-14132 A

  Accordingly, an object of the present invention is to make it possible to further increase the separation distance of each movable arm when performing measurement by the four-terminal pair method with a circuit board inspection apparatus called an XY type (or flying type). .

  In order to solve the above-described problems, the present invention provides a measurement unit including a measurement signal source and voltage detection means, and first and second current probes included in a measurement current path between the measurement signal source and the sample to be measured. And the first and second voltage probes included in the voltage detection path between the voltage detection means and the sample to be measured, and the predetermined probe are attached and moved in any direction of XYZ by the moving mechanism. The movement of each movable arm is controlled via the first and second movable arms to be driven and the moving mechanism, and the parameter of the sample to be measured is calculated based on the measurement signal from the measurement unit. In the circuit board inspection apparatus provided with the control unit, a coaxial cable is used for the electrical wiring to the measurement unit of each current probe and each voltage probe in order to perform measurement by the four-terminal pair method. The outer conductors of the coaxial cables are connected to each other through a predetermined conduction means, and the first current probe and the first voltage probe are supported by the probe support portion of the first movable arm. The second current probe and the second voltage probe are supported by the probe support portion of the second movable arm, and the X− of the first movable arm and the second movable arm. The coaxial cable holding means is supported at a substantially intermediate position between the first movable arm and the second movable arm via an expansion / contraction means that expands and contracts following the movement in the Y direction. The predetermined portion is held in a bundled state, and the inner conductor of each coaxial cable is connected to the corresponding probe via a deformable electrical relay means.

  In the present invention, the expansion / contraction means preferably employs a pantograph structure or a coil spring including two link levers articulated on two opposite sides.

  Further, according to a preferred aspect of the present invention, a circuit board is used as the conduction means, and the four insertion holes are inserted into the circuit board in a state where the outer conductor of each coaxial cable is exposed, A conductor pattern for connecting the external conductors formed between the insertion holes is provided.

  The first current probe supported on the first movable arm side and the first voltage probe are both on the high potential side and the second current probe supported on the second movable arm side. It is preferable that both of the second voltage probes are on the low potential side.

  The electrical relay means is preferably a leaf spring or a metal ribbon foil.

  According to the present invention, each of the four coaxial cables in which the respective outer conductors are connected to each other by the conducting means are bundled by the coaxial cable holding means, and approximately halfway between the first movable arm and the second movable arm. By being supported at the position, as each movable arm is moved, an electrical relay means for the two probes provided on the first movable arm side and the second movable arm side are provided. Since the electric relay means for the two probes that are arranged are deformed substantially evenly, the degree of freedom of movement of the movable arm is increased within a deformable range that the electric relay means can tolerate. Moreover, when each electrical relay means consists of a leaf | plate spring, for example, the load applied to them becomes substantially equal.

(A) The schematic diagram which shows the basic composition of the XY type | mold circuit board inspection apparatus of this invention, (b) The schematic diagram which shows the structural example of the probe by the 4 terminal pair method applied to this invention. The typical front view showing the concrete embodiment of the XY type circuit board inspection device of the present invention. The AA sectional view taken on the line of FIG. 2 which shows the structure of the expansion-contraction means with which embodiment of this invention is provided. The perspective view which shows the conduction | electrical_connection means with which embodiment of this invention is provided. (A), (b) The side view which shows the preferable example of the electrical relay means in this invention. (A)-(c) The schematic diagram which shows the operation example of the said expansion-contraction means. The schematic diagram which shows the modification of the said expansion-contraction means. The schematic diagram which shows the measurement state by a 4-terminal method. The schematic diagram which shows the measurement state by 4 terminal pair method.

  Next, an embodiment of the present invention will be described with reference to FIGS. 1 to 7, but the present invention is not limited to this.

  First, the configuration of the circuit board inspection apparatus of the present invention will be schematically described with reference to FIG. 1A. This circuit board inspection apparatus is an inspection apparatus called an XY type or flying type, and is basically As a simple configuration, the control unit 10, the measurement unit 20, a pair of movable arms 31 and 32, and movable arm moving mechanisms 41 and 42 are provided.

  For example, a microcomputer is used as the control unit 10, and an inspection program for the sample DUT to be measured existing on the circuit board A to be inspected, reference data for pass / fail judgment, and the like are set in the storage unit. Further, the control unit 10 calculates a parameter (for example, impedance) of the sample DUT to be measured based on the measurement signal from the measurement unit 20, and preferably performs quality determination or the like.

  As described above with reference to FIG. 9, the measurement unit 20 includes the measurement signal source 1 for performing measurement by the four-terminal pair method, the voltmeter 2 as the voltage detection means, the ammeter 3 as the current detection means, and feedback control. For this measurement, an automatic balancing bridge method using a low potential side voltage probe P4 as a virtual ground is applied.

  The movable arms 31 and 32 are driven in the XYZ directions by the moving mechanisms 41 and 42. The movement control signals of the movable arms 31 and 32 are given from the control unit 10 to the movement mechanisms 41 and 42. Although not shown, in addition to the movable arms 31 and 32, another movable arm (for example, a movable arm for a guard probe) may be provided.

  The XY direction is a direction in which the movable arms 31 and 32 move along a plane parallel to the substrate surface of the circuit board A to be inspected shown in FIG. 1 (if the left-right direction in FIG. 1 is the X direction, for example). 1 is a Y direction), and the Z direction is a vertical direction (vertical direction in FIG. 1) orthogonal to the substrate surface of the circuit board A to be inspected.

  As the inspection probe, four probes P1 to P4 based on the four-terminal pair method shown in FIG. 1B are used. Of these, as described in FIG. 9, P1 and P2 are current probes included in the measurement current path for the sample DUT to be measured, and P3 and P4 are voltage probes included in the voltage detection path of the sample DUT to be measured. It is.

  Probes having the same structure may be used for the current probes P1, P2, and the voltage probes P3, P4. In the description, when it is not necessary to distinguish between these probes, they may be simply referred to as probes.

  The probes P1, P2, P3, and P4 are connected to the measurement unit 20 via the inner conductors IL of the coaxial cables C1, C2, C3, and C4, respectively.

  Referring to FIG. 9, the current probe P1 of the current probes P1 and P2 is connected to the Hc terminal of the measurement signal source 1 on the high potential (Hi) side, and the current probe P2 is on the low potential (Low) side. It is connected to the Lc terminal side of the ammeter 3.

  Similarly, of the voltage probes P3 and P4, the voltage probe P3 is connected to the Hp terminal of the voltmeter 2 on the high potential side, and the voltage probe P4 is connected to the Lp terminal side of the voltage detection system as the low potential side.

  Each of the inner conductors IL of the coaxial cables C1 to C4 has one end connected to the proximal end b side of the probes P1 to P4 and the other end connected to the measuring unit 20, but the outer sides of the coaxial cables C1 to C4 The conductors (shield covered wires) S are connected to each other by, for example, lead wires 5 in the vicinity of the base end b side of the probes P1 to P4.

  Similarly, the outer conductors S of the low potential side coaxial cables C2 and C4 are also connected to each other by the lead wire 5 in the vicinity of the proximal end b side of the probes P2 and P4.

  In the present invention, the probes P1 to P4 for measurement by the four-terminal pair method are supported by movable arms 31 and 32 that can move in a predetermined direction, and the impedance of the sample DUT to be measured by the XY type circuit board inspection apparatus. Measure.

  Therefore, in this embodiment, as shown in FIG. 2, the high potential side current probe P1 and the high potential side voltage probe P3 are attached to the probe holding portion 32a on the one movable arm 32 side, and the low potential side current probe is connected. P2 and the low potential side voltage probe P4 are attached to the probe holding portion 31a on the other movable arm 31 side.

  In this embodiment, the probe holding portions 31a and 32a are arm portions included in the movable arms 31 and 32 oriented substantially parallel to the substrate surface of the circuit board A to be inspected, as shown in FIG. is there.

  Referring also to FIG. 3, in the present invention, in order to increase the freedom of movement of the movable arms 31 and 32, the expansion / contraction means 60 that expands and contracts following the movement of the movable arm 31 and the movable arm 32 in the XY direction. (60L), 60 (60R) is provided with a coaxial cable holding means 50 supported at a substantially intermediate position between the movable arm 31 and the movable arm 32. A predetermined portion of C4 is held in a bundled state, and the inner conductor IL of each of the coaxial cables C1 to C4 is connected to the corresponding probes P1 to P4 via the deformable electrical relay means 80, respectively.

  In this embodiment, the coaxial cable holding means 50 is arranged in two upper and lower stages (upper and lower two places) as 50A and 50B, but since the configuration is the same, one of the coaxial cable holding means 50 and the expansion / contraction means 60 is provided. The configuration of (60L) and 60 (60R) will be described with reference to FIG. 3 is a view along the line AA in FIG.

  The coaxial cable holding means 50 includes a cable holding substrate 51 through which four coaxial cables C1 to C4 are inserted. In this embodiment, the cable holding substrate 51 is formed in a disc shape, but may be formed in a square shape, for example. The material is preferably a non-magnetic material such as synthetic resin.

  Further, in this embodiment, the coaxial cables C1 to C4 are inserted through the cable holding board 51 so as to be positioned at the respective apexes of the quadrangle, but are inserted into the cable holding board 51 in a horizontal row or a vertical row. May be.

  The expansion / contraction means 60 includes expansion / contraction means 60L interposed between one movable arm 31 and the cable holding board 51, and expansion / contraction means 60R interposed between the other movable arm 32 and the cable holding board 51. Although included, the configuration is symmetrical with respect to the cable holding substrate 51, and therefore, one expansion / contraction means 60L will be described. In addition, when it is not necessary to distinguish between the expansion / contraction means 60L and 60R, the expansion / contraction means 60 is collectively referred to.

  In this embodiment, the expansion / contraction means 60L employs a pantograph structure including two link levers 61a, 61b; 62a, 62b that are articulated to two opposing link sides 61, 62, respectively.

  The first link lever 61a on the one link side 61 side and the first link lever 62a on the other link side 62 side have the same length, and the second link lever 61b on the one link side 61 side and the other link The second link lever 62b on the side 62 side has the same length. In this embodiment, the lengths of the first link levers 61a and 62a are longer than the lengths of the second link levers 61b and 62b, but they may be the same length or the opposite.

  On one link side 61 side, one end side of the first link lever 61a is connected to the cable holding substrate 51 via a hinge pin 61c, and the other end side is connected to one end side of the second link lever 61b via a hinge pin 61d. It is connected. The other end side of the second link lever 61b is connected to the movable arm 31 (the movable arm 32 on the expansion / contraction means 60R side) via a hinge pin 61e.

  Similarly, also on the other link side 62 side, one end side of the first link lever 62a is connected to the cable holding substrate 51 via a hinge pin 62c, and the other end side is connected to the second link lever 62b via a hinge pin 62d. It is connected to one end side. The other end side of the second link lever 62b is connected to the movable arm 31 (the movable arm 32 on the expansion / contraction means 60R side) via a hinge pin 62e.

  Each of the coaxial cables C1 to C4 has their outer conductor (shield covered wire) S exposed at a portion drawn from the cable holding substrate 51 of the lower coaxial cable holding means 50B. They are electrically connected to each other (electrically short-circuited).

  The conducting means 70 may be the lead wire 5 as shown in FIG. 1B, but in this embodiment, the circuit board 71 shown in FIG.

  The circuit board 71 has four insertion holes 71a to 71d that are inserted in a state where the outer conductors S of the respective coaxial cables C1 to C4 are exposed, and the outer portions formed between the insertion holes 71a to 71d. A conductor pattern 72 that connects the conductors S is provided.

  According to this, it is only necessary to solder each outer conductor S to the conductor pattern 72, and the lead wire 5 is not necessary, so that each outer conductor S can be easily electrically connected at the shortest distance. . The circuit board 71 may be integrally disposed on the lower surface side of the cable holding board 51 of the lower coaxial cable holding means 50B.

  Next, the inner conductors IL of the coaxial cables C1 to C4 supported by the lower cable holding substrate 51, and the probes P1 to P4 attached to the probe holding portions 31a and 32a of the movable arms 31 and 32, The electrical relay means 80 for connecting the two will be described.

  The electrical relay means 80 is required to be deformable following the movement of the movable arms 31 and 32 in the XYZ directions. Here, being deformable in the X, Y, and Z directions is desirably not only having flexibility but also having elastic restoring force (so-called spring elasticity).

  Therefore, in this embodiment, as the electrical relay means 80, as shown in FIGS. 5 (a) and 5 (b), at least part of the cable holding substrate 51 includes a curved portion 81a and the creepage distance is lower. A leaf spring 81 made of, for example, phosphor bronze having a length longer than the distance between the probe support portions 31a and 32a is used.

  As the electrical relay means 80, a ribbon foil made of a metal material such as aluminum may be used instead of the leaf spring 81. Moreover, the normal lead wire generally used as electrical wiring can also be used.

  As an operation example at the time of probing the movable arms 31 and 32, FIG. 6A shows a case where the movable arms 31 and 32 move in the direction approaching each other along the X direction, and FIG. 6B shows the movable arms 31 and 32. FIG. 6 (c) shows a case where the movable arms 31 and 32 move away from each other along the Y direction, respectively, according to the present invention. In either case, the coaxial cable holding means 50 is held at a substantially intermediate position between the movable arms 31 and 32 via the expansion and contraction means 60L and 60R having a pantograph structure.

  Accordingly, the leaf springs 81 and 81 connected to the probes P2 and P4 on the movable arm 31 side and the leaf springs 81 and 81 connected to the probes P1 and P3 on the movable arm 32 side are deformed almost equally. Therefore, the degree of freedom of movement of the movable arms 31 and 32 is increased within a deformable range that can be allowed by each leaf spring 81. In addition, the load applied to each leaf spring 81 is substantially uniform.

  As a modification of the expansion / contraction means 60, the link sides 61 and 62 may be tension coil springs 64a and 64b as shown in FIG.

  That is, the coaxial cable holding means 50 is held at a substantially intermediate position between the movable arms 31 and 32 by a total of four tension coil springs including the two left tension coil springs 64a and 64b and the two right tension coil springs 64a and 64b. May be.

  Even in this case, it is preferable that both ends of each tension coil spring are connected to the coaxial cable holding means 50 or the movable arms 31, 32 via hinge pins. As another simplified modification, as shown by a chain line in FIG. 7, the tension coil springs can be a pair of left and right.

  Further, in order to prevent damage to the electrical relay means 80 (plate spring 81) and disconnection of the connection portion, the distance between the movable arms 31 and 32 is within a predetermined range, although not shown. It is preferable that a tough wire or the like that is restricted to be hung.

  Further, on the assumption that one movable arm and the other movable arm support the current probe and the voltage probe, respectively, the high potential side and the low potential side may be interchanged in some cases. Such an embodiment is also included in the present invention.

1 Measurement signal source 2 Voltage detection means (voltmeter)
3 Current detection means (Ammeter)
5 Lead wire (conduction means)
DESCRIPTION OF SYMBOLS 10 Control part 20 Measurement part 31, 32 Movable arm 31a, 32a Probe holding part 41, 42 Movement mechanism 50 Coaxial cable holding means 51 Cable holding board 60 Expansion means 61, 62 Link side 61a, 61b, 62a, 62b Link lever 61c- 61e, 62c to 62e Hinge pin 70 Conducting means 71 Circuit board 71a to 71d Insertion hole 72 Conductor pattern 80 Electrical relay means 81 Leaf spring 81a Curved part A Test circuit board DUT Test sample P1, P2 Current probe P3, P4 Voltage probe C1-C4 Coaxial cable IL Inner conductor S Outer conductor (shielded wire)
FC feedback control circuit

Claims (6)

A measurement unit including a measurement signal source and a voltage detection unit; first and second current probes included in a measurement current path between the measurement signal source and the sample to be measured; the voltage detection unit; and the sample to be measured. First and second voltage probes included in the voltage detection path between the first and second movable arms, and the predetermined probes described above are attached and are driven in any direction of XYZ by a moving mechanism And a control unit that controls the movement of each movable arm via the moving mechanism and calculates a parameter of the sample to be measured based on a measurement signal from the measurement unit. In
In order to perform the measurement by the four-terminal pair method, a coaxial cable is used for the electrical wiring leading to the measurement part of each current probe and each voltage probe, and the outer conductors of each coaxial cable are connected to each other through a predetermined conduction means. Connected to each other,
The first current probe and the first voltage probe are supported on a probe support portion of the first movable arm, and the second current probe and the above-described probe are supported on a probe support portion of the second movable arm. A second voltage probe is supported,
Nearly between the first movable arm and the second movable arm via expansion / contraction means that expands and contracts following movement in the XY direction of the first movable arm and the second movable arm. The coaxial cable holding means supported at the position is held in a state in which the predetermined portions of the coaxial cables are bundled,
The circuit board inspection apparatus, wherein the inner conductor of each coaxial cable is connected to the corresponding probe via a deformable electrical relay means.   2. The circuit board inspection apparatus according to claim 1, wherein the expansion / contraction means has a pantograph structure including two link levers that are articulated on two opposite sides.   The circuit board inspection apparatus according to claim 1, wherein the expansion / contraction means comprises a coil spring.   A circuit board is used as the conduction means, and the circuit board is formed with four insertion holes that are inserted in a state where the outer conductors of the coaxial cables are exposed, and the insertion holes formed between the insertion holes. The circuit board inspection apparatus according to claim 1, further comprising a conductor pattern that connects the external conductors to each other.   The first current probe supported on the first movable arm side and the first voltage probe are both on the high potential side, and the second current probe supported on the second movable arm side and the above 5. The circuit board inspection apparatus according to claim 1, wherein both of the second voltage probes are on a low potential side.   6. The circuit board inspection apparatus according to claim 1, wherein a plate spring or a metal ribbon foil is used as the electrical relay means.

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