JPH0614260B2 - Board inspection method - Google Patents

Description

The present invention relates to a substrate inspecting method, and more particularly to a substrate inspecting method suitable for inspecting a substrate having a large number of pixel electrodes such as a liquid crystal substrate. .

(Prior Art) In recent years, for example, liquid crystal display devices and the like have been highly integrated in pixels, and liquid crystal display devices having 200,000 to 300,000 pixels have also been developed.

In such a liquid crystal display device, a transparent electrode having a passivate film, an alignment film, etc. is formed for each pixel on a substrate such as a glass substrate. An active element such as a MOS TFT is arranged in each pixel.

Similarly, a substrate on which a transparent electrode having a passivation film, an alignment film and the like is formed for each pixel is arranged in close proximity to the substrate, and a liquid crystal is sealed between these substrates. .

When inspecting such a liquid crystal display device substrate, it is necessary to measure, for each pixel, for example, whether the operation of the MOS TFT is good or not, and whether or not there is a disconnection. Further, it is not preferable to directly contact the transparent electrode with an electrical connection terminal or the like. Therefore, the inspection is performed by visually checking the display image of the assembled liquid crystal display device and making a check.

(Problems to be Solved by the Invention) However, in the conventional inspection method described above, the inspection can be performed only after the final assembly,
For example, there is a problem that productivity is deteriorated, for example, a defective substrate is sent to an assembly process.

The present invention has been made in consideration of such conventional circumstances, and can easily inspect a board before assembly.
An object of the present invention is to provide a substrate inspection method capable of improving productivity.

[Structure of the Invention] (Means for Solving Problems) That is, according to the substrate inspection method of the present invention, a vibrating body having a conductor layer is arranged in close proximity to an electrode formed on a substrate to be measured, and the vibration is generated. An alternating voltage is applied between the body and the electrode, and the vibration generated in the vibrating body is detected to inspect the substrate to be measured.

(Operation) In the substrate inspection method of the present invention, the vibrating body having the conductor layer is arranged in close proximity to the electrodes formed on the substrate to be measured,
An AC voltage is ignited between the vibrating body and the electrodes to detect the vibration generated in the vibrating body, so that the substrate to be measured such as the liquid crystal display substrate is inspected before assembly.

That is, capacitive coupling is formed between the transparent electrode of the substrate for a liquid crystal display device and the vibrating body, and minute vibration of the vibrating body generated by the action of the AC electric field is detected. Therefore, it is not necessary to directly contact the transparent electrode or the like with the electrical connection terminal or the like, and the substrate can be easily inspected.

(Examples) Examples of the substrate inspection method of the present invention will be described below with reference to the drawings.

On a glass substrate 1 of the active matrix type liquid crystal display device shown in FIGS. 1 and 2, a large number of pixels 2 having transparent electrodes, passivate films, alignment films and the like are formed. Each of these pixels 2 has a MOS type TFT.
3 are arranged, and the gate of the MOS TFT 3 is connected to the gate signal line 4 and the source is connected to the source signal line 5, respectively. The drains of the MOS TFTs 3 are connected to the transparent electrodes in the pixels 2, respectively.

The gate signal line 4 and the source signal line 5 are connected to the lead electrode 6 and the lead electrode 7 arranged at the ends of the glass substrate 1, respectively.

In the method of this embodiment, first, the vibrating body 8 is arranged so as to face the glass substrate 1, that is, face the transparent electrode of the pixel 2a to be measured. The vibrating body 8 includes, for example, a plastic sheet 8a having a thickness of about several microns, and a conductor layer 8b made of, for example, sputtering on the opposite side of the plastic sheet 8a and made of aluminum and having a thickness of, for example, about 0.1 to 1 μm. , A frame 8c made of aluminum or the like, which is formed in a grid pattern corresponding to the pixels 2 and holds the plastic sheet 8a.

Next, the source signal line 5 to which the measured pixel 2a is connected
An AC voltage is applied between the transparent electrode of the measured pixel 2 a and the vibrating body 8 via the lead electrode 7 at the end. Also,
A pulsed ON signal, for example, is applied to the gate of the MOS TFT 3 via the lead electrode 6 at the end of the gate signal line 4 to which the measured pixel 2a is connected.

Then, the vibration generated in the plastic sheet 8a of the vibrating body 8 with respect to the transparent electrode of the measured pixel 2a at this time is
For example, the laser light source 9 that irradiates the surface of the conductor layer 8b with a laser beam and the television camera 10 that detects the reflected light from the conductor layer 8b are detected by, for example, observing a change in interference fringes on the surface of the conductor layer 8b.

That is, at this time, there is no disconnection in the gate signal line 4 and the source signal line 5 to which the measured pixel 2a is connected, and the MO
If the S-type TFT 3 operates normally and there is no abnormality in the transparent electrode of the measured pixel 2a, an AC electric field acts between the transparent electrode of the measured pixel 2a and the vibrating body 8 to cause the vibrating body 8 to move.
Vibration occurs in the plastic sheet 8a. Therefore, if the vibration is detected by the television camera 10, the measured pixel 2a can be determined to be normal.

Even if the vibration is detected by performing position control of the laser light source 9 and the television camera 10 and moving each pixel or every several pixels, the entire vibrating body 8 is irradiated with the laser light and vibrates. You may perform using the television camera 10 which can image the whole body 8.

Further, the electric capacitance C (pF) between the transparent electrode of the measured pictol 2a and the vibrating body 8 can be obtained by the following equation, where ε is the relative permittivity, A is the electrode area, and d is the interval.

C (pF) = 0.225εA / d Therefore, the transparent electrode of the measured pixel 2a and the vibrating body 8
The voltage applied between and is appropriately selected depending on the area of the transparent electrode, the distance between the transparent electrode and the vibrating body 8, and the like.

That is, in this example method, the vibrating body 8 having the conductor layer 8b is arranged so as to face the transparent electrode of the pixel 2a to be measured, and capacitive coupling is formed to apply an AC voltage. Then, an ON signal is applied to the gate of the MOS TFT 3 to inspect the measured pixel 2a. Therefore, for example, it is not necessary to directly contact the transparent electrode with an electrical connection terminal or the like, and the inspection can be easily performed.

[Advantages of the Invention] As described above, according to the board inspection method of the present invention, it is possible to easily inspect the board before assembly, and it is possible to significantly improve the productivity as compared with the related art.

[Brief description of drawings]

FIG. 1 is a perspective view of a liquid crystal display device substrate for explaining a substrate inspection method according to an embodiment of the present invention, and FIG. 2 is a top view. 1 ... Glass substrate, 2 ... Pixel, 8 ... Vibrator, 8
a: plastic sheet, 8b: conductor layer, 8c ...
flame.

Claims (2)

[Claims] 1. A vibrating body having a conductor layer is arranged in close proximity to an electrode formed on a substrate to be measured, and an AC voltage is applied between the vibrating body and the electrode to apply the AC voltage to the vibrating body. A substrate inspection method, which comprises inspecting the substrate to be measured by detecting the generated vibration. 2. The substrate inspection method according to claim 1, wherein the substrate to be measured is a substrate for a liquid crystal display device having an active element.