JPH11118867A - Method and device for inspecting defective electrode on substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To specify the position of a disconnection defect along the direction of length by use of an inexpensive device which allows conditions to be set easily and which requires only a short inspection time. SOLUTION: An inspection probe 8a and an inspection brush 8b which are made of conductors are provided in contact with each other, over electrodes 3 formed on a glass substrate 2, and are connected to an inspection circuit having a power supply E and a resistance R, to monitor a voltage V(=IR) where 1 is a current flowing in the circuit. When the inspection brush 8b moves over the lines of electrodes 3 toward the inspection probe 8a, a change in voltage V(=IR) occurs from a disconnection defect part 6. The site of the change is specified as the position of the disconnection defect part 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for inspecting a defective electrode on a substrate for inspecting a defect of an electrode formed on a glass substrate of a liquid crystal display device. The present invention relates to a method and an apparatus for inspecting a defective electrode on a substrate that can be specified.

[0002]

2. Description of the Related Art In recent years, as a display device used in a computer or the like, a matrix type display device using a liquid crystal has been widely used in place of a display device using a cathode ray tube. In such devices, large-screen or high-resolution liquid crystal display devices have been developed to increase the amount of data that can be displayed on the screen at one time, and the electrodes formed on the substrate have become smaller patterns. ing. Therefore, the occurrence of defective substrates increases due to a decrease in yield, and the defective substrates are repaired. Further, in order to reduce the cost of the liquid crystal display device, a defective substrate is repaired.

A liquid crystal display device as described above uses a matrix type liquid crystal substrate. An ordinary matrix type liquid crystal substrate has two glass substrates each having I
A transparent X electrode and a transparent Y electrode made of TO or the like are formed by an etching process, and the electrode forming surfaces of the respective substrates are arranged to face each other in a matrix, and liquid crystal is sealed between the glass substrates.

When the electrodes are formed on a glass substrate as described above, the defects shown in FIGS. 7B and 7C may occur. Such a defect is caused by the inclusion of foreign matter during the etching process or a defective etching process.
(B) is a short-circuit defect in which a part of adjacent lines are in contact with each other, and (C) is a disconnection (open) defect in which a part of the same line is missing. Is shown.

[0005] With respect to the short-circuit defect (B), it is possible to specify the line of the short-circuit defect and the position of the line where the short-circuit defect occurs by using a conventionally used inspection device. did it. On the other hand, for the disconnection defect of (C), the visual processing of an image processing apparatus or an operator relies.

[0006]

However, for the disconnection defect shown in FIG. 7C, it is possible to specify which line of the electrode has the disconnection defect, but the position in the length direction is determined by the measurement principle. Could not be identified. Therefore, the line on the electrode 3 is monitored by a method based on image processing using a camera and a monitor, or an operator visually monitors the line.

In the case of the above image processing, the apparatus itself is very expensive because a dedicated camera or monitor is used, and it is not easy to set conditions such as illumination for illuminating the substrate.
Furthermore, there is a problem that processing is slow for the investment amount. In addition, since the liquid crystal electrode pattern is formed with a very fine pattern, the above-described visual inspection requires a very long time to perform the inspection, and also causes defects. There was a risk of oversight and lack of certainty. Further, the above-described inspection is extremely nervous, and has a problem that a considerable burden is imposed on an operator.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and it is possible to specify the position in the length direction of a disconnection defect by using an inexpensive apparatus which can easily set conditions and has a short inspection time. It is an object of the present invention to provide a method and an apparatus for inspecting a defective electrode on a substrate that can be performed.

[0009]

A method for inspecting a defective electrode on a substrate according to the present invention is a method for inspecting a defective electrode on a substrate for identifying the location of a disconnection defect of an electrode formed on the substrate.
A first conductor is brought into contact with one of the electrode lines, and a second conductor is brought into contact with the other, and a current value or a voltage value between the first conductor and the second conductor is monitored, and a defect is generated. It is characterized by specifying the electrode.

By the above means, the first conductor is brought into contact with one end in the length direction of the electrode, and the second conductor is brought into contact with the other end, and the conductivity between the two conductors on the electrode is inspected. At this time, if a disconnection defect occurs in the electrode, no current flows between the two conductors, and if a disconnection defect does not occur in the electrode, current flows between the two conductors. By monitoring the current value or the voltage value generated in the circuit, it is possible to specify which line of the electrode has the disconnection defect.

In addition, it is possible to move at least one of the conductors along the defective electrode, and monitor a change in the current value or the voltage value at this time to specify a defective portion on the electrode. .

When the position in the line direction of the electrode having the disconnection defect is specified as described above, at least one of the first and second conductors moves while sliding on the electrode. If the two conductors are present on different sides from the disconnection defect, there is no change in the current value or voltage value, and if the brush-shaped conductor moves and both conductors are on the same side, conduction between the two conductors occurs. As a result, the current value or the voltage value changes. As described above, the exact position of the defective electrode is specified.

In this case, it is preferable that the conductor to be moved along the electrode has a wide brush shape extending over a line of an adjacent electrode.

Since the electrodes formed on the liquid crystal display substrate are very fine, if the movable conductor at the time of inspection of a defective electrode is a needle-like conductor, the conductor may come off the electrode line during the movement. Inspection errors occurred, and the position of the defect was not reliably specified. Therefore, a considerably high-precision correction device was required for positioning the substrate. However, as described above, one conductor was formed in a brush shape, and By forming so as to straddle adjacent electrodes, a high-precision correction device is not required for positioning the substrate, and an inspection error can be prevented.

Further, the present invention is an inspection apparatus for a defective electrode on a substrate for specifying the position of a disconnection defect of an electrode formed on the substrate, wherein the first electrode is in contact with one end of a line of an electrode having a disconnection defect. A conductor, a second conductor in contact with the other end of the line, a moving device for moving at least one of the first conductor and the second conductor along the electrode, and a test for monitoring current or voltage between the two conductors And a circuit.

According to the above-mentioned apparatus, an inexpensive apparatus can be constituted without using an expensive apparatus, and an inspection can be surely and quickly performed.

The substrate of the present invention is typified by a glass substrate of a liquid crystal display device, but may be another IC mounting substrate or the like.
Etc., but other copper foil or gold foil electrodes may be used.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for inspecting a defective electrode on a substrate according to the present invention will be described below with reference to FIGS. FIG.
FIG. 2A is an explanatory view showing the entire device from inspection to repair of the substrate, FIG. 2A is a top view showing the positional relationship between the substrate and the inspection device, and FIG. 2B is a side view and a circuit diagram thereof. Normally, as shown in FIG. 7, a substrate used in a liquid crystal display device has an X electrode or a Y electrode 3 made of a material such as ITO formed on a glass substrate 2 by etching at regular intervals in a line shape. . As shown in FIG.
A disconnection defect 6 as shown in FIG.

An apparatus for specifying the position of the disconnection defect 6 as described above is an inspection apparatus 8 shown in FIG. The inspection device 8 includes an inspection probe 8a as a first conductor,
The inspection brush 8b and the inspection circuit 8c as conductors. The glass substrate 2 on which the electrodes 3 are formed is placed on the table 12 shown in FIG. 1 and the inspection of the electrodes 3 is performed. After the glass substrate 2 is positioned, an inspection probe 8a and an inspection brush 8b composed of two conductors
Are arranged at both ends of the line of the electrode 3. If necessary, the position of the glass substrate 2 can be finely adjusted by moving the table 12 in the XY direction or the θ direction.

The tip of the inspection probe 8a is formed in a needle shape. The inspection brush 8b is
It is formed wide so as to straddle the line of the adjacent electrode 3, so that even if the inspection brush 8 b is slightly shifted from the line of the electrode 3, an inspection error does not occur. It is preferable to use a conductive brush having a soft tip so that the electrode 3 is not damaged. The inspection probe 8a and the inspection brush 8b are connected to an inspection circuit 8c. The test circuit 8c has a power supply E, a resistor R, and a voltmeter for measuring a voltage V flowing through the resistor R. Both ends of the test circuit 8c are connected to the test probe 8a and the test brush 8b, respectively. Have been. The resistor R has a resistance sufficiently larger than that of the electrode 3.

When the electrode 3 is formed normally,
A current I flows between the electrodes 3 to make the circuit conductive, and a voltage V (= IR) is generated at the resistor R. On the other hand, when the disconnection defect portion 6 exists in the electrode 3, the entire circuit does not conduct, and no current flows through the resistor R, so that no voltage is generated. By monitoring the presence or absence of this voltage value (V) on a monitor, it is possible to specify in which line of the electrode 3 the disconnection defect 6 occurs. Subsequently, the defect position in the length direction of the electrode 3 is specified.

As shown in FIGS. 2A and 2B, the inspection brush 8b starts moving in the direction of the inspection probe 8a, that is, from the inspection probe 8a, and inspects the location where the disconnection defect portion 6 is generated. In this case, the inspection brush 8b is
Move while sliding on top. At this time, no voltage is generated in the resistor R in a state located before the disconnection defect portion 6, and a voltage is generated at a point in time when the resistance R exceeds the disconnection defect portion 6. Then, the position of the disconnection defect 6 is specified. As described above, the line in which the disconnection defect portion 6 occurs and the location of the line can be accurately specified.

As shown in FIG. 1, the inspection device 8 is connected to a moving device 13c and a control device 11, and can move the inspection probe 8a and the inspection brush 8b by the moving device 13c. The operation is controlled by 11 and the position data of the disconnection defect 6 is stored, and this data is sent to the next device for restoration. FIG. 1 shows the entire apparatus from inspection to repair of the glass substrate 2 on which the electrodes 3 are formed, and is composed of an inspection device 8, a transfer device 4, a heating device 5, and a control device 11.

When the disconnection defect portion 6 is specified by the above-described method and apparatus, the transfer device 4 is operated next. The transfer device 4 includes a transfer probe 4a, a moving device 13a, and a plate paste 1c. The transfer device 4 is controlled by the control device 11 so that the transfer probe 4a can appropriately move between the transfer probe 4a and the disconnection defect portion 6. The plate paste 1c is formed of a base 4d and a plate frame 4c, and the paste 1 is poured into the plate frame 4c and is flattened by a squeegee or the like to form a plate paste 1c. The heating device 5 includes a semiconductor laser 5a and a moving device 13b.

FIG. 3 shows a process of repairing the substrate having the disconnection defect portion 6. The paste 1 is transferred to the disconnection defect portion 6 by the transfer probe 4a, and then the paste 1 is baked by the semiconductor laser 5a. The semiconductor laser 5a is connected to the moving device 13b, and is controlled by the control device 11 so that the semiconductor laser 5a can freely move to the upper part of the paste 1 formed in the disconnection defect portion 6.

The operation of the transfer probe 4a will be described with reference to FIG. 4. First, the transfer probe 4a is in the initial state (i).
Is moved onto the plate paste 1c from (ii) and lowered (iii). Next, the transfer probe 4a is pushed in until it reaches the bottom of the plate paste 1c.
By raising a, a certain amount of paste 1 is transferred to the tip of the transfer probe 4a. At this time, FIG.
As shown in (A), a coil spring 7 is provided as an elastic body inside the transfer probe 4a, and when the transfer probe 4a reaches the bottom of the plate paste 1c, the biasing force of the coil spring 7 is reduced. Against the force F from the top of the transcription probe 4a
Is pressed. Next, the transfer probe 4a is moved onto the disconnection defect portion 6 (iv) and lowered (v). Then, by raising the transfer probe 4a, the paste 1 is separated from the transfer probe 4a, the paste 1 is transferred to the disconnection defect portion 6, and returns to the initial state (i) (vi).

The material of the transfer probe 4a is preferably beryllium-copper.
As shown in (B), it is preferable that the tip portion has a flat shape 4b in terms of facilitating transfer. The use of the above-described transfer probe 4a eliminates the need for a highly accurate positioning mechanism or control. When changing the amount of paste 1 to be transferred, plate paste 1
This can be easily handled by changing the depth of c.

Paste 1 comprising an organic compound of the metal
Is not a gold paste based on gold powder, but is formed by bonding gold atoms to an organic substance, and is entirely formed of a liquid paste. As such a paste 1, it is preferable to use a MOD (metallo organic deposition) type gold paste based on a gold resinate, and among them, a paste for low-temperature firing is preferable. The pre-repair substrate 10 made of the paste 1 transferred to the disconnection defect portion 6 as described above is shown in FIG.
, Where the paste 1 is fired.

A semiconductor laser 5a is used as a heating source of the heating device 5 used in the firing, and firing is performed by irradiating near infrared rays having a wavelength of about 810 nm. Although not shown, the semiconductor laser 5a is obtained by unitizing a plurality of semiconductor elements, and laser light emitted from each element is bundled using a glass fiber and condensed by a lens unit. It is formed so that the object can be irradiated with light.

When the above-described semiconductor laser 5a is used, as shown by the arrow in FIG. 3B, the portion irradiated to the paste 1 absorbs the laser beam, generates heat, and is heated. However, the other portions are not absorbed by the laser beam and pass through the electrode 3 and the glass substrate 2. That is, the semiconductor laser 5a uses an element that emits near-infrared light, and since the paste 1 exemplified above has a black color, the near-infrared light is absorbed. Therefore, only the portion of the transferred paste 1 is subjected to the heat treatment, and the other portion of the glass substrate 2 does not generate heat, and the glass substrate 2 is not damaged. Further, in the semiconductor laser 5a, the output intensity of the laser light can be easily controlled, whereby the disconnection defect portion 6 can be obtained as a high quality fired portion in firing the paste 1.

As an example for obtaining the above-mentioned high-quality fired portion, a profile shown in FIG. 6 can be mentioned. That is, after first increasing to a predetermined output (0
８8 seconds), fixed time stepwise (8 to 16 seconds, 16 to 24)
(Second), a low output is maintained, and at this time, preliminary firing is performed to remove the solvent in the liquid paste 1. After that, by maintaining the high output for a certain period of time (24 to 34 seconds), the main firing is performed to deposit the metal component, and after the firing is completed, the output is gradually lowered (34 to 42 seconds) to cool down. Done. Through the above-described steps, a high-quality metal thin film 1a in which the deposited portion of the metal formed in the disconnection defect portion 6 has no crack and is dense can be obtained. Note that the above profile is an example, and can be changed as appropriate depending on the transfer amount of the paste 1 and the like.

As described above, the disconnection defect portion 6 is repaired, a metal thin film 1a made of a metal precipitate as shown in FIG. 3C is obtained, and the repaired substrate 10a is obtained. As described above, the transfer device 4 transfers the paste 1 made of a metal organic compound to the disconnection defect 6 generated in the electrode 3 on the glass substrate 2, and the paste 1
Is burned by the heating device 5 composed of the semiconductor laser 5a, and only the metal component in the paste 1 is precipitated to repair the defective portion.

[0033]

According to the method of inspecting a defective electrode on a substrate of the present invention, the position of the defective electrode on the substrate can be specified not only in the line direction but also on the line.

The inspection apparatus of the present invention can be constituted by an inexpensive apparatus including two movable conductors and a simple inspection circuit, and can surely and quickly inspect. Further, by using the above-described inspection device, the worker can surely find the defect without overlooking the defect, and reduce the burden on the worker by eliminating the need for extremely nervous work. Is what you can do.

Further, the cost of the liquid crystal display substrate can be reduced by using such an inexpensive inspection device and increasing the working speed.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an entire apparatus including an inspection apparatus of the present invention and a repair apparatus associated therewith;

2A is a plan view showing an arrangement of the inspection apparatus, FIG. 2B is a side view thereof, and a circuit diagram connected to the inspection apparatus;

FIGS. 3A, 3B, and 3C are process diagrams showing a method for repairing a defective electrode; FIGS.

FIG. 4 is an explanatory diagram showing the operation of a transfer probe.

FIG. 5 (A) is a front view showing the structure of a transcription probe,
(B) is an enlarged view,

FIG. 6 is a profile showing the relationship between time and output in firing,

FIG. 7 is a plan view illustrating an electrode formed on a substrate,
(A) indicates normal, (B) indicates a short-circuit defect, (C) indicates a disconnection defect,

[Explanation of symbols]

 2 Glass substrate 3 Electrode 6 Disconnection defect 8 Inspection device 8a Inspection probe 8b Inspection brush 8c Inspection circuit E Power supply R Resistance V Voltage I Current

Claims (4)

[Claims] 1. A method for inspecting a defective electrode on a substrate for identifying the location of a disconnection defect of an electrode formed on the substrate, wherein a first conductor is provided on one of the electrode lines and a second conductor is provided on the other. A method for inspecting a defective electrode on a substrate, comprising: contacting and monitoring a current value or a voltage value between the first conductor and the second conductor to identify a defective electrode. 2. The method according to claim 1, wherein at least one of the conductors is moved along the defective electrode, and a change in the current value or the voltage value at this time is monitored to identify a defective portion on the electrode. An inspection method for defective electrodes on a substrate. 3. The method for inspecting a defective electrode on a substrate according to claim 2, wherein the conductor moved along the electrode has a wide brush shape extending over a line of an adjacent electrode. 4. An inspection apparatus for a defective electrode on a substrate for specifying a position of a disconnection defect of an electrode formed on the substrate, comprising: a first conductor contacting one end of a line of an electrode having a disconnection defect; A second conductor that contacts the other end of the line, a moving device that moves at least one of the first conductor and the second conductor along the electrode, a test circuit that monitors a current or voltage between the two conductors, An inspection apparatus for a defective electrode on a substrate, comprising: