JP2899116B2 - Z-axis origin search device for in-circuit tester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Z-axis origin finding device for an in-circuit tester used for judging the quality of a mounting board.

[0002]

2. Description of the Related Art Conventionally, a mounting board, that is, a printed board on which a large number of electrical components are soldered, uses an in-circuit tester to appropriately contact probe pins to required inspection points on the board, and to electrically connect each of those components. The quality of the substrate is determined by the measurement. In particular, the one in which the XY unit is installed on the measuring table on which the substrate to be inspected is mounted is provided with a Z-axis unit movable in the Y-axis direction on the arm movable in the X-axis direction, and the Z-axis unit is Probe pin to Z
Since the XY unit is supported movably in the axial direction, when the XY unit is controlled, the probe pins are moved from above the substrate to X
By appropriately moving in the directions of the axis, the Y axis, and the Z axis, it is possible to sequentially contact the inspection points set in advance. At this time, a servomotor is used for the reciprocating motion of the arm in the X-axis direction and the reciprocating motion of the Z-axis unit in the Y-axis direction, and an air cylinder is used for the reciprocating motion of the probe pin in the Z-axis unit in the Z-axis direction. And solenoids.

[0003]

However, if an air cylinder or the like is used as a drive source for reciprocating the probe pins in the Z-axis direction, the probe pins can only reciprocate a predetermined distance, and the substrate to be inspected can be moved. Cannot reciprocate an appropriate distance in accordance with the protruding state of each component mounted on the device. Therefore, useless movement increases, the moving distance of the probe pin increases, and the moving time increases, so that the inspection cannot be speeded up.

Accordingly, the present applicant has previously provided a stepping motor in a Z-axis unit as a probe pin support mechanism of an XY unit for an in-circuit tester (Japanese Patent Application No. 2-186925), and a slide member mounted on the motor mounting member. The guide rail of the unit is fixed, the probe pin is held by a slider that reciprocates along the guide rail, the slider is connected to the rotating shaft of the stepping motor by a crank, and the slider is connected to the slider in the longitudinal direction of the guide rail. It has been proposed to fix a member in which first and second slits are sequentially arranged at intervals along the length, and to install a photo interrupter for detecting the slit near the moving region of the slit member.

At the time of inspection, the first and second slits are used to detect the top dead center, which is the origin of movement of the probe pin in the Z-axis direction, according to the degree of protrusion of each component mounted on the board to be inspected. After the selection, the number of pulses of the control signal to be applied to the stepping motor was selected, the tip of the probe pin was quickly moved downward, and was sequentially brought into contact with a preset inspection point on the substrate surface. As a result, the probe pin does not move unnecessarily.

However, the Z-axis origin finding apparatus has a problem because it has a configuration in which an X pulse is applied to a stepping motor and a probe pin is largely moved so as to approach a substrate to be inspected. Incidentally, the tip of the probe pin moves toward the substrate to be inspected by X pulses so as to approach the distance between the first and second slits, for example, 15 mm. Therefore, if a tall component or the like is erroneously mounted, the pin tip hits the component and cannot move by X pulses toward the substrate to be inspected, and the Z-axis origin search device loses synchronism, and the probe pin The movement origin in the Z-axis direction cannot be determined.

The present invention has been made in view of such a conventional problem, and the probe pins are not always out of step according to the degree of protrusion of each component mounted on the substrate to be inspected, and the probe pins are not lost. It is an object of the present invention to provide a Z-axis origin finding device for an in-circuit tester capable of finding a moving origin in the Z-axis direction.

[0008]

Means for achieving the above object will be described below with reference to FIG. 1 which clarifies the present invention. The Z-axis origin search device of this in-circuit tester includes a stepping motor 28, and a motor mounting member 32 thereof.
A guide rail 38 of a slide unit 36 is fixed to the probe unit 30, a probe pin 30 is held by a slider 40 that reciprocates along the guide rail 38, and the slider 40 and a rotating shaft 34 of the stepping motor 28 are connected by a crank 44. Then, a member 50 in which first and second slits 46 and 48 are sequentially arranged at intervals along the longitudinal direction of the guide rail 38 is fixed to the slider 40, and the slit member 50 is provided.
X with a Z-axis unit 26 provided with a photo interrupter 52 for detecting slits 46 and 48 near the movement area of
-Pertaining to a device having a Y unit.

The width of the first slit 46 provided in the slit member 50 is made equal to the movement width of the slit member 50 for one pulse entering the stepping motor 28 which can be detected by the photo interrupter 52.
Reference numeral 8 denotes a position where the width of the slit member 50 is equal to the movement width of the slit member 50 having two or more pulses entering the stepping motor 28 and is detected by the photo interrupter 52 when the crank 44 hits the stopper 54.

Further, until the photo interrupter 52 detects one of the first and second slits 46 and 48, a pulse signal is sent to the stepping motor 28 one pulse at a time in a direction in which the tip of the probe pin 30 moves away from the substrate to be inspected. When a pulse signal is given to the stepping motor 28 one pulse at a time in a direction in which the tip of the probe pin 30 approaches the substrate to be inspected until the slit detecting means 62 and the photo interrupter 52 no longer detect the slit, and the slit is not detected. A detection slit origin aligning means 6 for giving one pulse signal in the direction in which the tip of the probe pin 30 moves away from the substrate to be inspected and aligning the slit with the moving origin.
4 and one pulse signal to the stepping motor 28 in the direction in which the tip of the probe pin 30 moves away from the substrate to be inspected, it is determined whether or not the photo interrupter 52 has detected the slit. There is provided a detection slit discriminating means 66 for determining the slit 48 and determining the slit as the first slit 46 when the slit is not detected.

[0011]

With the construction described above, the photo-interrupter 52 is switched by the slit detecting means 62 to the first and second slits 46, 4 and 4.
Until one slit 8 is detected, a pulse signal is given to the stepping motor 28 one pulse at a time, and the probe pin 30 is moved. At this time, even if a tall component or the like is erroneously mounted, the probe pin 30 moves in a direction away from the substrate to be inspected, so that the pin tip does not hit the component or the like.

However, the detection slit origin aligning means 64
Until the photo interrupter 52 detects the slit, the pulse signal is applied to the stepping motor 28 one pulse at a time, and the tip of the probe pin 30 moves so as to approach the substrate to be inspected. For this reason, if the detected slit is the second slit 48, it must move by the slit width at the longest, but the first slit 46
Is a length corresponding to one pulse, so that the width of the second slit 48 is at least a length corresponding to two pulses in order to distinguish it from the first slit 46. Therefore, even if the width of the second slit 48 is set to two or more pulses, the number of pulses may be small, and the moving distance of the probe pin 30 is short, so that the pin tip does not hit a mounted component. Then, when the slit is no longer detected, a one-pulse signal is given to the stepping motor 28, the tip of the probe pin 30 is moved away from the substrate to be inspected, and the slit is adjusted to the origin of movement.

The detecting slit discriminating means 64 gives one pulse signal to the stepping motor 28 and
Is moved away from the substrate to be inspected, and it is determined whether the slit is detected. Then, when detecting, the slit is determined as the second slit 48, and when not detecting, the slit is determined as the first slit 46.
As a result, the detection slit can be determined, and its current position becomes clear.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 2 is a plan view showing an arrangement relationship of the in-circuit tester to which the present invention is applied on a measuring table on which a substrate to be inspected is installed. FIG. 3 is a front view showing a Z-axis unit of the XY unit for the in-circuit tester in detail. FIG. In FIG.
Reference numeral 10 denotes a measuring table of the in-circuit tester, 12 denotes a substrate to be inspected installed at the center thereof, and 14 (14a, 14b) denote two sets of XY units installed at symmetrical positions around the periphery.

The XY unit 14a includes an X-axis driving servomotor 16 mounted on the measuring table 10,
6, the ball screw 18 which is rotated by the ball screw 18
20 that moves in the X-axis direction by the rotation of
The servo motor 22 for driving the Y-axis installed at 0, a ball screw 24 rotated by the motor 22, a Z-axis unit that moves in the Y-axis direction by the rotation of the ball screw 24, and the like. Stepping motor 28
A probe pin 30 that moves in the Z-axis direction. Note that the arm 20 or the Z-axis unit 2
In order to know the position of 6, a position detection switch 31 (31a, 31b) such as a photo switch or a proximity switch is also provided.

If the Z-axis unit 26 is provided with a probe pin support mechanism as shown in FIG. 3, the rotation of the stepping motor 28 in the A (reverse) direction or the B (forward) direction indicated by the arrow will cause the probe pin to rotate. It can be converted into a linear motion in the Z-axis direction indicated by the arrow 30. For this reason, a strong square plate 32 is used as a vertical support for supporting the probe pin support mechanism, and the main body of the stepping motor 28 is attached to the central part on one side, and the rotating shaft 34 of the motor 28 is mounted on the other side. Slide unit 36 with protrusion and probe pin 30
And so on near the lower left corner.

The slide unit 36 is a guide rail 3
8 and a slider 40, and a holder 42 for attaching the probe pin 30 to the right front portion of the slider 40.
Is fixed and used. At the time of attachment, the upper end of the guide rail 38 is fixed near the left corner of the support plate 32 and arranged in the Z-axis direction, and the slider 40 and the like are hung. Then, the tip of the probe pin 30 arranged in parallel along the longitudinal direction of the guide rail 38 from the tip of the slider 40 is projected downward. Further, the probe pin holder 42 of the slider 40 and the rotating shaft 34 of the stepping motor 28 are
The first and second slits 46 are formed on the front left side of the slider 40 along the longitudinal direction of the guide rail 38.
48, an elongated plate 50 arranged at a required interval is fixed. The hole provided in the center of the link 51 of the crank 44 is for reducing the weight.

The first and second slits 46 are provided on a part of the support plate 32 near the center of the movement area of the slit plate 50.
A photo-interrupter 52 having a light-emitting device and a light-receiving device for detecting 48 is installed. The width of the first slit 46 is made equal to the movement width of the slit plate 50 for one pulse entering the stepping motor 28 which can be detected by the photo interrupter 52, and the width of the second slit 48 is set to two or more pulses entering the stepping motor. The number of pulses is made equal to the movement width of the slit plate 50 for three pulses, for example. Further, in order to prevent erroneous detection of the slits 46 and 48, a stopper 54 for preventing the stepping motor 28 from rotating more than a predetermined amount in the direction A is fixed to the support plate 32.
And a corresponding protruding piece 56 integrated therewith. Moreover,
When the projecting piece 56 moves in the direction A and hits the stopper 54, the photo interrupter 52 can detect the second slit 48.

FIG. 4 is a block diagram showing a signal circuit relating to the Z-axis unit. As shown in FIG.
When a control signal is supplied to the stepping motor 28 from the driver 60 and a pulse is generated from the driver 60, the motor 28 rotates in the forward or reverse direction according to the number of pulses. This rotational movement is transmitted to a slider 40 via a crank 44 connected to a rotating shaft 34 of the motor 28, and reciprocates linearly along a guide rail 38 disposed in the Z-axis direction. Then
Along with the slider 40, the probe pin 30 and the slit plate 50 held thereon also make a linear motion in the Z-axis direction. Therefore, if the photo interrupter 52 is installed near the moving area of the slit plate 50, the first and second slits 46 and 48 can be detected, and the signal can be sent to the controller 58.

The controller 58 is, for example, a microcomputer, a CPU (central processing unit), a ROM
(Read only memory), RAM (read / write memory), input port, output port, bus line and the like. The CPU corresponds to the brain which is the center of the microcomputer, and according to the instructions of the program,
It controls the entire in-circuit tester, performs arithmetic and logical operations, and temporarily stores the results. It also controls peripheral devices. ROM
Stores a control program for controlling the entire in-circuit tester, a probe pin movement origin detection processing program, and the like. The RAM stores various data such as input data, calculation data, and measurement data.

The input port is connected to an input unit having a data input key and the like.
, And signal lines for the X-axis and Y-axis driving servomotors 16 and 22, the arm position detection switch 31, and the like. The output port is connected to a display for displaying various data and the result of determination on the quality of the mounting board. Not only a signal line is output to the driver 60 for driving the stepping motor, but also a signal line is output to each driver for driving the servo motor. coming out. The bus lines include an address bus line, a data bus line, a control bus line, and the like for connecting them, and are also connected to peripheral devices.

Next, a probe pin position detecting operation will be described. FIG. 5 is a flowchart showing a probe pin moving origin detection processing program. This processing program is executed by steps P1 to P10. First, at P1, it is determined whether the photo interrupter 52 has detected one of the first and second slits 46 and 48. If NO, go to P2. At P2, a control signal is sent from the controller 58 to the driving driver 60, and the stepping motor 28
, A one-pulse signal is supplied, and it is rotated in the A direction. For this reason, until the photo interrupter 52 detects one of the slits, the tips of the probe pins 30 sequentially move away from the substrate 12 to be inspected. Therefore, even if a tall component or the like is erroneously mounted, the pin tip does not hit the component or the like. If YES, go to P3.

At P3, a one-pulse signal is given to the stepping motor 28 to rotate it in the B direction. Next, go to P4.
In P4, it is determined whether the previously detected slit is detected again. In the case of YES, the process returns to P3. Therefore, the tip of the probe pin 30 sequentially approaches the substrate to be inspected 12 until the photo interrupter 52 no longer detects the slit. At this time, the detected slit is the first slit 46.
In the case of, the pin tip has a slit width of one pulse, for example, 0.5
mm. In the case of the second slit 48, at the longest point, the pin tip approaches a slit width of three pulses, for example, 1.5 mm, but the moving distance of the probe pin 30 is much smaller than the distance between the first and second slits 46, 48, for example, 15 mm. It is short and its pins do not hit the mounted components. N
In the case of O, go to P5.

At P5, a one-pulse signal is given to the stepping motor 28 to rotate it in the A direction. Then, the detection slit can be made to coincide with the movement origin. At this time, if the detected slit is the first slit 46, the detection position of the photo interrupter 52 and the position of the first slit 46 match, and that position becomes the movement origin. However, in the case of the second slit 48, the detection position of the photointerrupter 52 coincides with the upper position corresponding to the width of one pulse of the second slit 48, and that position becomes the movement origin. Next, go to P6.

At P6, a one-pulse signal is given to the stepping motor 28 to rotate it in the A direction. Next, go to P7.
At P7, it is determined whether the slit is detected again according to the movement origin. If NO, go to P8. At P8, it can be seen that the slit corresponding to the movement origin is the first slit. Therefore, the current tip position of the probe pin 30 is also clarified. If YES, go to P9. At P9, it can be seen that the second slit 48 is the slit aligned with the movement origin. Therefore, the current tip position of the probe pin 30 is also clarified.

When the distance between the first and second slits 46 and 48 and the tip of the probe pin 30 is determined using the slit plate 50 connected to the slider 40 as described above,
Since these distances can be kept constant, two origins (top dead center) of the movement of the probe pin 30 can be accurately set at the positions of the slits 46 and 48 even if there is play in the crank 44. . Next, go to P10. At P10, since the origin of the movement of the probe pin 30 has been clarified, the process proceeds to the next process. Incidentally, when the crank mechanism is arranged symmetrically with respect to FIG. 3, the directions A and B in the flowchart are exchanged.

At the time of inspection, a top dead center, which is the origin of movement of the probe pin 30 in the Z-axis direction, is selected according to the degree of protrusion of each component mounted on the substrate 12 to be inspected, and control to be applied to the stepping motor 28 The number of pulses of the signal is selected, the tip of the probe pin 30 is moved downward, and sequentially contacts a predetermined inspection point (measurement land) on the substrate surface. As a result, the top dead center of the probe pin 30 can be arbitrarily selected by the first slit 46 or the second slit 48, and the bottom dead center can be arbitrarily selected by the number of pulses, so that the probe pin 30 does not move unnecessarily. Therefore, a measurement current is applied to each component through the probe pin 30 or the like, or a measurement voltage is applied,
By measuring the resistance value, the capacitance value, the inductance value, and the like, it is possible to determine the quality of the inspection target substrate 12.

[0028]

According to the present invention described above, when a slit is detected, a pulse signal is applied to the stepping motor one pulse at a time until the slit is detected, and the probe pin moves in a direction away from the substrate to be inspected. Even if a tall component or the like is erroneously mounted, the tip of the probe pin does not naturally hit the component or the like. However, when the detection slit is aligned with the origin of movement, a pulse signal is given to the stepping motor one pulse at a time until the slit is no longer detected, and the probe pin is moved in a direction approaching the substrate to be inspected. However, since it is only the width of the slit, the pin tip does not hit the mounted component. Therefore, the origin of the movement of the probe pin in the Z-axis direction can always be accurately determined in accordance with the degree of protrusion of each component mounted on the board to be inspected without the step-out of the apparatus.

Further, the protruding distance for moving the probe pin from each origin and contacting each inspection point can be arbitrarily selected from the number of pulses applied to the stepping motor. Therefore, by making the probe pins reciprocate an appropriate distance corresponding to the mounting state of the board to be inspected, unnecessary movement is eliminated, the moving distance is shortened, the moving time is reduced, and the inspection speed is achieved. it can.

[Brief description of the drawings]

FIG. 1 is a diagram showing a Z-axis origin finding device of an in-circuit tester according to the present invention.

FIG. 2 is a plan view showing an arrangement relationship on a measurement table on which a substrate to be inspected is installed in an in-circuit tester to which the present invention is applied.

FIG. 3 shows Z of the XY unit for the in-circuit tester.
It is a front view which shows a shaft unit in detail.

FIG. 4 shows the Z of the XY unit for the in-circuit tester.
It is a block diagram showing a signal circuit about a shaft unit.

FIG. 5 is a flowchart showing a probe pin movement origin detection processing program stored in a memory of the in-circuit tester.

[Explanation of symbols]

14 XY unit 28 Stepping motor 3
0 ... Probe pin 32 ... Motor mounting member 34 ... Rotating shaft 36 ... Slide unit 38 ... Guide rail 40 ...
Slider 44 ... Crank 46, 48 ... First and second
Slit 50 ... Slit member 52 ... Photo interrupter 54 ... Stopper 56 ... Protruding piece 58 ... Controller 60 ... Stepping motor drive driver 62 ...
Slit detecting means 64: detecting slit origin matching means 66: detecting slit discriminating means

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01R 31/28 G01R 1/06 H01L 21/66

Claims (1)

(57) [Claims] A stepping motor is provided, a guide rail of a slide unit is fixed to a motor mounting member, a probe pin is held by a slider reciprocating along the guide rail, and a rotating shaft of the slider and the stepping motor is provided. Are connected to each other by a crank, and a member in which first and second slits are sequentially arranged at intervals along the longitudinal direction of the guide rail is fixed to the slider, and the slit is detected in the vicinity of the moving region of the slit member. In a Z-axis origin finding device for an in-circuit tester having an XY unit with a Z-axis unit provided with a photo interrupter, the first slit provided in the slit member enters a stepping motor whose width can be detected by the photo interrupter. The width of the slit member must be equal to the pulse width, and the width of the second slit must be After making it equal to the movement width of the slit member with the number of pulses of 2 or more pulses entering the ping motor,
Provided at a position where the photo interrupter can detect when the crank hits the stopper, and applies a pulse signal to the stepping motor one pulse at a time in the direction in which the tip of the probe pin moves away from the substrate to be inspected until the photo interrupter detects one slit. A pulse signal is supplied to the stepping motor in a direction in which the tip of the probe pin approaches the substrate to be inspected until the slit detecting means and the photo interrupter no longer detect the slit. A one-pulse signal is given in a direction away from the substrate to be inspected, a detection slit origin aligning means for aligning the slit with the movement origin, and a one-pulse signal is given to the stepping motor in a direction in which the tip of the probe pin is away from the substrate to be inspected, The interrupter cuts the slit The in-circuit tester is characterized by comprising: a detection slit discriminating means for judging whether or not the slit has been ejected, determining the slit as the second slit when detecting, and determining the slit as the first slit when not detecting. Z-axis origin search device.