JP3246028B2 - Automatic material testing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to an automatic material testing machine that loads a minute work such as a chip.

[0002]

2. Description of the Related Art FIG. 13 shows an example of this type of work, I.
It is a figure explaining a C chip. In this example, the IC chip 1 is connected to a surrounding base 2 by a bonding wire 3,
The base 2 is held by a bonding wire 3.

[0003]

As an example of such an evaluation test of the IC chip 1, there is a method of judging whether or not the wire bonding 3 is broken when a predetermined load is applied vertically to the center of the IC chip. However, with a conventionally known material testing machine, it is difficult to set a work and position the work with respect to a load shaft, and it is not possible to apply a small load of about 10 mg.

[0004] It is an object of the present invention to provide an automatic material testing machine capable of efficiently setting a small work on the material testing machine and applying a small load.

[0005]

An automatic material testing machine according to the present invention comprises: a fixing means for fixing a work frame on which a plurality of works are individually set; an XY stage for positioning the work frame in an XY plane; A Z stage for positioning the work frame in a Z-axis direction orthogonal to the XY plane; an imaging unit for imaging the set work; and a calculation for calculating a load point of the work by image processing of the imaged image Means, load means for loading the work, and control means for driving and controlling the XY stage so that the calculated load point of the workpiece coincides with the load axis of the load means. Achieve the above objectives.

[0006]

The work is captured by the imaging device while being accommodated in the work frame fixed to the fixing means, and the image is processed to calculate the load point of the work. The XY stage is moved such that the calculated load point coincides with the load axis of the load means, and the work is loaded by the load means.

[0007]

1 to 13 show an embodiment of the present invention. FIG. 1 shows the entire configuration of an automatic material testing machine according to the present invention, wherein 100 is a testing machine main body arranged on a gantry 101 via a vibration isolation mechanism 102, and 200 is a testing machine main body 10
0 control unit. As shown in FIG. 2, the tester main body 100 includes an XY stage 110 for positioning a work in an XY plane, and a sample holder 130 for holding a pallet P on which a plurality of works are individually set on the XY stage.
A microscope 160 (shown in detail in FIG. 7) for observing the work set on the sample holder 130;
An imaging device 165 that captures an image in a field of view of zero;
In order to focus the workpiece 5 on the work, a Z stage 170 for positioning in the Z-axis direction orthogonal to the XY plane, and the sample holder 1
The pallet P includes a load mechanism 180 that loads a workpiece in the pallet P held by the pallet 30 and a displacement sensor 185 that detects a displacement of the workpiece due to the load. The tester main body 100 is entirely covered with a windshield case 186. The image of the microscope 160 can be observed with the naked eye from the eyepiece 162 shown in FIG.
When observing with the naked eye without inserting the prism 163, the prism 163 is inserted. 161a and 161b are objective lenses, respectively.

FIG. 3 shows a pallet P for setting a work on the tester main body 100. The pallet P is provided with a plurality of work chambers PR partitioned into a mesh shape, and as shown in FIG.
Each accommodates one of the works shown in FIG.
Load mechanism 180 for the work housed in work room PR
A load is applied vertically by the indenter.

FIG. 5 is a diagram showing the details of the sample holder 130. The sample holder 130 has a table 131 installed on a Z stage 170, and four rectangular pallets P are fixedly set on the table 131. Table 1
Fixed holding members 132 and 133 are provided on the upper side and the left side of the table 31, respectively. A pair of movable holding members 134 and 135 are provided on the lower side and the right side of the table 131, respectively. Tools 132 and 13
The pallet P is set by pressing the pallet 3.
Each of the holding members 132 to 135 is provided with a tapered surface T extending from the upper surface side to the bottom surface side, and the peripheral edge of the pallet P is fixed to the table 131 side by this tapered surface.

A pair of movable holding members 134 on the lower side penetrate a fixed plate 137 fixed on one support plate 136.
The guide rods 138 are attached to the guide rods 138, and A
Biased in the direction. The support plate 136 is supported at both ends by a pair of guide rods 141 penetrating a pair of support members 140 that move in the A direction along a pair of linear guides 139, and the spring 1 stretched between the support members 140.
The support plate 136 is urged downward by 42. A pair of rollers 143 are provided on the lower surface of the support plate 136, and the rollers 143 slide on the upper surface of the cam plate 144. The cam plate 144 has a slope 144a having an upward slope inside the table. When the holding member 134 is moved in the direction A, the roller 143 goes up the slope and the movable holding member 134 is moved.
Moves to the back of the table while ascending.

A bar 145 extends toward the back of the table of the support member 140, and a cam follower 146 is provided at the tip thereof. The cam follower 146 has a cam surface 147 provided on the support plate 147 of the right-hand movable retainer 135.
When the movable presser 134 on the lower side moves in the direction A, the support plate 147, that is, the right side movable presser 135 moves in the direction B. When the lower side movable presser 134 is pushed in the direction A and the pallet P is set by pressing the fixed pressers 132 and 133 with the movable pressers 134 and 135 and the operation of the movable presser 134 in the direction A is released, the lock member is released. 14
8 and 149 are engaged with each other to hold the holding members 134 and 13 at that position.
5 is locked, and the pallet P is set on the table 131. In this state, when the movable presser 134 is pushed inward, the lock is released, the movable presser 134 is pulled forward by the spring 150, and the movable presser 135 is returned rightward, whereby the pallet P is removed. You. Note that the movable presser 135 can be configured in the same manner as the movable presser 134, and the movable presser 135 moves in the B direction along the linear guide 151.

FIG. 6 is a conceptual diagram of the load mechanism 180. This load mechanism 180 uses a mechanism used for a well-known electronic balance in reverse to an electronic balance.
The load generating unit 181 is composed of a permanent magnet 181a and a force coil 181b. When a current flows through the force coil 181b, the force coil 181b is connected to the fulcrum 1.
The indenter 184 provided at the tip of the indenter support bar 183 can be pressed against the work by rotating around the 82 in the direction of the arrow. The load for pressing the work by the indenter 184 is proportional to the current flowing through the force coil 181b. Numeral 185 denotes a differential transformer type displacement meter whose core 185 a is held by an L-shaped portion 183 a at the tip of an indenter support bar 183 so as to follow the displacement of the indenter 184.

FIG. 7 is a side sectional view taken along line VV in FIG. 2. Reference numeral 162 denotes an eyepiece of the microscope 160, through which the work can be observed. 16
Reference numerals 3 and 164 denote prisms, and 166 denotes an illumination device. Illumination light from the illumination device 166 is reflected downward by the prism 164 to illuminate the workpiece. The luminous flux from the work passes through the prism 164 and is guided to an imaging device 165 such as a CCD camera, while being reflected by the prism 163 to the left in the figure and guided to the eyepiece 162.

As shown in FIG. 1, the control section 200 includes a personal computer 210, a monitor 215 for the personal computer,
A monitor 216 for displaying the image captured by the image capturing device 65; and an image processing device 2 for processing the image captured by the image capturing device 165.
20, a measurement control unit 230 that receives a signal from a load sensor and a displacement sensor 185 (not shown) to control the load, and an autofocus device that focuses the imaging device 165 on a workpiece based on an image captured by the imaging device 165. 240 and X
It has a motor controller 250 that controls driving of the Y stage 110 and the Z stage 170. 260 is a power supply box.

FIG. 8 shows a block diagram of the control unit 200.
Each device is connected with a personal computer 210 as a core as shown in the figure. As shown in FIG. 9, the measuring unit 230 includes a converter 231 that converts a digital signal under a load condition set by the personal computer 210 into a digital signal, a current amplifier 232 that amplifies the signal from the converter 231 and energizes the force coil 181b. A voltage dividing resistor 233 for dividing a current signal from the force coil 181b into a voltage value, a voltage / frequency converter 234 for converting a voltage signal extracted by the voltage dividing resistor 233 into a frequency, / Counter 235 for counting frequency signals from frequency converter 234
A voltage / frequency converter 236 for converting a voltage signal from the displacement meter 185 into a frequency, and a voltage / frequency converter 236
And a counter 237 for counting the frequency signal from

The autofocus device 240 fetches the video image picked up by the image pickup device 165 into a memory as a luminance signal of 256 gradations, counts the number of pixels for each luminance, and
A histogram as shown in FIG. Here, FIG. 11A shows a histogram when the focus is out of focus, and FIG. 11B shows a histogram when the focus is out of focus. The image in focus has a high variance value as shown in FIG. 11B, and the residual value is very sensitive to the image. When the variance value is calculated in the direction in which the image is out of focus,
As shown in FIG. 12, the maximum value is always obtained at the focus position. The autofocus device 240 determines whether or not the subject is in focus based on the variance value of the luminance histogram, and drives the Z stage 170 so that the subject is in focus.

The image processing device 220 obtains a position matching the previously registered search pattern from the video image picked up by the image pickup device 165, and places the work at an appropriate position, for example, the center (load point) with the load axis. The XY stage 110 is driven so as to match. Specifically, an image P (M, N) of a pattern to be searched and an image B (X,
A correlation coefficient C _ij with the partial image B _ij (M, N) of Y) is obtained, and coordinates whose value is larger than the reference value are output. A deviation between this coordinate value and the coordinate value of the center of the visual field of the imaging device 165 is calculated.

A test procedure by the automatic material testing machine thus configured will be described. (1) Each work is set in each work room PR 4
The pallets P are fixed to the sample holder 130. In this fixing procedure, as described above, the lower movable holding member 134 is fully operated inside the table, and the locking members 148 and 1
It is only necessary to lock 49 with. (2) The XY stage 110 is roughly driven to an initial position where the center of the first work to be tested substantially coincides with the optical axis of the imaging device 165. (3) The image picked up by the image pickup device 165 is taken into the autofocus device 240, and the work is focused on as described above.

(4) The image picked up by the image pickup device 165 is taken into the image processing device 220, and the pattern matching is performed as described above to determine the deviation between the center of the work and the center of the visual field of the image pickup device 165. (5) XY so that the deviation obtained in this way becomes zero.
The stage 110 is driven. Thus, the center of the work coincides with the center of the visual field of the imaging device 165. (6) The work is lowered by a predetermined amount by the Z stage 170 so that the work does not collide with the indenter 184, and the work center is determined based on the known coordinates of the center of the visual field of the imaging device 165 and the known coordinates of the load axis of the load mechanism 180. Drive the XY stage 110 so that
To raise the work by a predetermined amount to the height position before the movement.

(7) The coil current corresponding to the load set from the personal computer 210 is applied to the force coil 181b.
Turn on electricity. The coil current actually flowing through the force coil 181b is converted into a voltage signal by the voltage dividing resistor 233, and the actual load is calculated by the personal computer 210 based on the voltage signal and displayed on the load display. (8) The actual position of the indenter 184 is monitored based on the signal from the displacement meter 185, and a limiter is applied so that the indenter 184 does not fall below a predetermined position. By such limiter control, there is no possibility that the load mechanism 180 undesirably loads the pallet P. Of course, the load speed and the displacement speed may be controlled by feeding back the load and the displacement.

According to the present embodiment, a workpiece is imaged by an imaging device such as a CCD camera, and is auto-formed by image processing.
The position of the work is calculated by performing image processing on the captured video image and performing image processing on the video, and the load point of the work is made to coincide with the load axis of the load mechanism based on the calculation result. As described above, it is possible to accurately and efficiently match the load point of the minute work with the load axis. Further, since the load generating portion is constituted by the force coil and the permanent magnet, a minute load (for example, from 10 mg to 200
The control of g) becomes easy. Further, when setting the pallet P on the sample table 130, it is only necessary to operate one of the movable pressers 134, and the setting of the pallet P becomes extremely easy. Further, the work is transferred to the work room P of the pallet P.
Since it is only necessary to place the work on the R, it is very easy to set the work on the pallet P.

In the above description, an IC chip is described as an example of a minute work.
Various small works other than the C chip can be targeted. Also, the load mechanism 180 using electromagnetic force has been described as an example, but a load mechanism that generates a load by another method may be used. The pallet for accommodating the work is not limited to the embodiment, and various forms are possible. The work may be pressed one by one on the pallet.

In the above embodiment, the sample holder 130 constitutes the fixing means, the imaging device 165 constitutes the imaging means, the personal computer 210 constitutes the calculating means and the control means, and the load mechanism 180 constitutes the loading means.

[0024]

As described in detail above, according to the present invention, an image of a minute work is taken in, the point of load is calculated by an image processing method, and the point of load of the work coincides with the load axis. Thus, the load point can be accurately and efficiently made to coincide with the load axis even if the work is minute, and the test accuracy can be improved and the test time can be shortened.

[Brief description of the drawings]

FIG. 1 is a front view of an example of an automatic material testing machine according to the present invention.

FIG. 2 is a detailed view of the tester main body of FIG.

FIG. 3 is a plan view of a pallet.

FIG. 4 is a view showing a work set on a pallet;
(A) is a plan view thereof, (b) is a bb sectional view of (a).

FIG. 5 is a view showing a sample holder, wherein (a) is a plan view,
(B) is a front view, (c) is a right side view.

FIG. 6 is a schematic explanatory view of a load mechanism.

FIG. 7 is a VV side view of FIG. 2;

FIG. 8 is a block diagram of a control unit.

FIG. 9 is a detailed block diagram of a measuring unit.

FIG. 10 is a diagram showing a histogram of luminance.

11A and 11B are diagrams showing a luminance histogram according to a focus state, where FIG. 11A shows a case where the subject is out of focus, and FIG. 11B shows a case where the subject is focused.

FIG. 12 is a graph showing a relationship between a focus position and a variance value.

FIG. 13 is a perspective view showing an example of a minute work.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 Test machine main body 110 XY stage 130 Sample holder 160 Microscope 165 Imaging device 170 Z stage 180 Load mechanism 185 Displacement meter 200 Control unit 210 Personal computer 220 Image processing device 240 Autofocus device

Continuation of the front page (56) References JP-A-4-89552 (JP, A) JP-A-1-118341 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 3 / 04 G01N 3/40 G06T 7/00 JICST file (JOIS)

Claims (1)

(57) [Claims] 1. A fixing means for fixing a work frame on which a plurality of works are individually set; an XY stage for positioning the work frame in an XY plane;
A Z stage for positioning in the Z-axis direction orthogonal to the Y plane; an imaging unit for imaging the set work; a calculation unit for calculating a load point of the work by image processing of the imaged image; An automatic material, comprising: a load unit that loads the workpiece; and a control unit that controls the drive of the XY stage so that the calculated load point of the workpiece coincides with the load axis of the load unit. testing machine.