JPH08236881A - Method for inspecting circuit board and circuit - Google Patents

Abstract

PURPOSE: To provide a method for inspecting a circuit, especially inspecting a circuit of high integration density such as an LCD panel, etc., precisely and swiftly. CONSTITUTION: Phototransistors FX1, FY1 which produce electromotive forces by electromagnetic waves are connected to an LCD panel 1 beforehand. And at the time of inspecting the LCD panel 1, electromagnetic waves are applied to the phototransistors, and abnormality of the LCD panel 1 is detected without contact by generating an electromotive force without contact and applying voltage to each circuit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to, for example, an LCD (Liquor
The present invention relates to a technique for inspecting a circuit such as an id crystal display panel, and particularly to a method for inspecting a circuit in a non-contact state.

[0002]

2. Description of the Related Art Conventionally, in a device including, for example, an electronic computer or an LCD panel, a plurality of electronic circuits are connected to a PCB.
It is usually formed integrally on a circuit board such as a (printed circuit board). In such a case, the entire device may malfunction due to the occurrence of an abnormality in some electronic circuits. Also, for example, when some display electrodes in the LCD panel have poor contact,
When there is an abnormality in a component of the panel, a so-called pixel lacking state occurs, which hinders the display function.

For this reason, when a plurality of electronic circuits are integrated on a single circuit board, it is necessary to inspect each individual electronic circuit for abnormalities such as contact failure. . In this inspection, conventionally, an inspection electrode is brought into contact with a terminal electrode of a circuit to be inspected on a circuit board, and a predetermined electric power is supplied to the electronic circuit through the inspection electrode. Then, it is carried out by confirming whether or not the circuit operates normally.

[0004]

By the way, in recent years, the number of electronic circuits in each device has increased along with the multifunctionalization and performance improvement of electronic devices. There is a demand for higher integration density. As a result, a large number of circuits are integrated in a small area on the circuit board, the terminals of the electronic circuit are small, and the terminals are arranged close to each other. Therefore, it is extremely difficult to bring the inspection electrode into accurate contact with the terminal electrode of the circuit to be inspected. In particular, when an LCD panel is inspected, it is very difficult to inspect whether the circuit connected to the pixel is normal, that is, whether the pixel emits light normally because the pixel integration density is high. .

Further, even in the case of simply inspecting an electronic circuit, when the inspection electrode is mechanically brought into contact with the electronic circuit, alignment, maintenance of accuracy and wear of the inspection electrode become problems. Particularly, in the case of inspecting a large number of circuit lines simultaneously with the inspection electrodes during inspection, the positional accuracy, uniformity, and abrasion resistance must be high. For this reason, a highly accurate contact terminal unit for inspection is required and its cost is also high. The present invention has been made in view of the above background, and an object thereof is to provide a technique capable of accurately and quickly inspecting an electronic circuit, particularly when the circuit integration density is high, such as an LCD panel. To provide.

[0006]

In order to solve the above-mentioned problems, the present invention forms a plurality of circuit lines on a circuit board for mounting an electronic circuit, and further, at a predetermined portion of the circuit lines, It is characterized in that an electromotive force exciting element having a predetermined shape for exciting electromotive force when sensing an electromagnetic wave is formed. It is preferable that the circuit board has an unnecessary area to be removed after the inspection, and the electromotive force excitation element is formed in the unnecessary area.

In order to solve the above problems, the present invention is also characterized in that a photoelectric element for exciting electromotive force when light is sensed is formed on a circuit line arranged corresponding to a pixel.
CD panel is also provided.

Further, when forming an electronic circuit on a circuit board, an electromotive force exciting element having a predetermined shape for exciting electromotive force when sensing an electromagnetic wave is connected in advance to a predetermined portion of the electronic circuit, At the time of inspection, there is also provided a circuit inspection method characterized in that the electromotive force excitation element corresponding to the electronic circuit to be inspected is irradiated with electromagnetic waves.

Further, in the manufacturing process of the LCD panel, the photoelectric element is previously made conductive to the circuit line arranged corresponding to each pixel, and at the time of inspection of the LCD panel, the photoelectric element is made conductive to the pixel to be inspected. There is also provided a method for inspecting an LCD panel, which comprises irradiating a light beam on the surface. In this case, it is preferable that a marker corresponding to each photoelectric element is formed at a predetermined portion of the LCD panel, and the irradiation direction of the light beam is specified by using the marker as an index when the light beam is irradiated.

Light is usually used as the electromagnetic wave used in the above-mentioned circuit board and the method for inspecting the circuit board.
X-rays, radio waves, magnetic forces, etc. may be used. By using electromagnetic waves, it is possible to excite electromotive force in the element that is the target of electromagnetic wave irradiation, without making mechanical contact. When light is used as the electromagnetic wave, the electromotive force excitation element is not particularly limited, but, for example, a photoelectric element can be used. Specific examples thereof include phototransistors, and photodiodes, photocells, solar cells, and the like may be used. Furthermore, the circuit is normally inspected in a closed state, but the circuit at the time of inspection need not necessarily be closed. Even when the circuit is open, some transient phenomenon (a phenomenon in which electric charge is momentarily transferred) appears due to the occurrence of electromotive force. Therefore, it is necessary to use this phenomenon to determine whether the circuit is abnormal or not. You can also INDUSTRIAL APPLICABILITY The present invention is useful for inspection of circuits such as integrated circuits in which it is difficult to inspect individual circuits by a mechanical method.

[0011]

A plurality of circuit lines are formed on a circuit board for mounting an electronic circuit, and an electromotive force exciting element having a predetermined shape for exciting electromotive force when an electromagnetic wave is detected is formed at a predetermined portion of the circuit line. As a result, a circuit board suitable for the inspection of the circuit line itself and the inspection of the electronic circuit mounted on the circuit is provided.
When the circuit is inspected, the circuit and the electronic circuit are energized by irradiating the electromotive force excitation element with an electromagnetic wave, and the circuit and the electronic circuit can be inspected in a non-contact manner. The electromotive force excitation element may be unnecessary after the circuit is inspected, and the circuit board may have an unnecessary region to be removed after the inspection. In this case, by forming the electromotive force excitation element in the unnecessary region, this element can be removed without providing a new removal step. In particular, in an LCD panel in which a photoelectric element that excites an electromotive force when sensing light is formed on a circuit line arranged corresponding to a pixel, the LCD panel can be easily and quickly inspected.

In this way, the circuit board or L to be inspected
By providing an electromotive force excitation element such as a photoelectric element on the CD panel in advance, and irradiating the electromotive force excitation element with electromagnetic waves such as light (preferably a non-divergent one such as a laser beam) at the time of inspection, non-contact The inspection is done. If the circuit to be inspected or the pixel of the LCD performs a predetermined normal operation, it is determined that the inspection target is normal, and if the normal operation cannot be obtained, it is determined that there is some abnormality. Also, in general,
The detection of the positioning marker is easier and quicker than the direct detection of the position of the electromotive force excitation element itself. Therefore, by forming a marker corresponding to the electromotive force excitation element on the substrate and irradiating the electromagnetic wave using this marker as an index, the irradiation direction of the electromagnetic wave can be easily and quickly determined.
In particular, when the LCD panel is shipped, the photoelectric element used for the circuit inspection is unnecessary and is preferably removed. Usually, a part of the substrate of the LCD panel is removed as an unnecessary area at the time of shipping. Therefore, by forming the photoelectric element in this unnecessary area, the photoelectric element is removed by simply executing the conventional LCD panel manufacturing line. . It is not necessary to newly provide a step of removing the photoelectric element.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows an explanatory diagram of an LCD panel inspection method according to this embodiment. In this figure, 1 is an LCD panel body to be inspected, 2 is a voltage control power source, 3 is a variable resistor, and X1 is an X formed on this LCD panel.
Of the electrodes, the X electrode in the first column is shown. Similarly, Y1 is the Y of the first column among the Y electrodes formed on this LCD panel.
The electrodes are shown. FX1 is a phototransistor directly connected to the electrode X1, and FY1 is a phototransistor directly connected to the electrode Y1. Further, MX1 and MX2 indicate markers corresponding to FXI and FY1, respectively, and these markers are minute reflecting mirrors. Note that phototransistors are provided in advance on all electrodes of the LCD panel. Further, in each drawing, the same parts are designated by the same reference numerals.

Pixels are arranged at the respective intersections of the X electrodes and the Y electrodes. This pixel has a configuration in which it is sandwiched by two electrodes and two polarizers whose polarization angles are deviated from each other by 90 degrees. Twisted nematic (T
In the N) type LCD panel, the liquid crystal has its molecular orientation twisted by 90 degrees, so that the light incident on the pixel (usually the backlight of the LCD panel) has its polarization plane rotated by 90 degrees by the liquid crystal. Normally, the incident light on the pixel is polarized by the polarizing plate on the incident side, and the polarization angle is twisted by 90 degrees when passing through the liquid crystal. As described above, since the polarizers on the emission surface side are arranged with the polarization angles shifted by 90 degrees, the emission light and the polarizers on the emission surface side have the same polarization plane, and the emission light from the liquid crystal is the same as the polarizer. Pass through. Therefore, the pixel is in the bright state.

On the other hand, when a voltage is applied, the twist of the liquid crystal is released, the molecules are rearranged in the direction of the electric field, and the plane of polarization does not rotate. Therefore, when a voltage is applied, the polarization plane of the light emitted from the liquid crystal and the polarization plane of the polarizer on the emission surface side are deviated from each other by 90 degrees, and the light emitted from the liquid crystal is blocked by the polarizer on the emission surface side. Therefore, the pixel is in a dark state.

In a super twisted nematic (STN) type LCD panel, the molecular orientation of liquid crystal is twisted by 270 degrees (-90 degrees). Even in this case, the orientation plane of incident light is shifted by 90 degrees. Can be treated like.

If there is no abnormality in the circuit on the X electrode side directly connected to the pixel to be inspected and the circuit on the Y electrode side, by applying a voltage to these X electrode and Y electrode,
The bright / dark state of the pixel can be controlled normally. Therefore, by applying a voltage to the X electrode and the Y electrode directly connected to the pixel to check whether the light / dark state of the pixel is normally controlled, each circuit on the X electrode side and the Y electrode side of each pixel is inspected. can do. In this example, the X electrode and Y
The state where no voltage is applied to both electrodes is the initial state. Therefore, in the initial state, each pixel is in a state in which the backlight of the LCD panel is transparent, that is, in a bright state.

Hereinafter, focusing on the pixel at the intersection of the electrode X1 and the electrode Y1, each circuit on the X electrode side and the Y electrode side directly connected to this pixel is inspected. As described above, each pixel is in the bright state in the initial state. When a voltage is applied to both the X electrode and the Y electrode directly connected to the pixel to be inspected, this pixel is in a dark state when there is no abnormality in each circuit. Usually, when a voltage is applied to each of the X and Y electrodes, the inspection electrode is mechanically brought into contact after the inspection electrode is accurately aligned with the terminal of the electrode to which the voltage is applied. However, in this embodiment, as shown in FIG. 1, phototransistors are provided in advance at the ends of all electrodes of the LCD panel. Therefore, it is not necessary to mechanically contact each electrode with the inspection electrode, and voltage can be applied in a contactless manner by irradiating the phototransistor provided on the electrode to be inspected with light.

At this time, at the time of laser irradiation, alignment was performed with reference to each marker. Specifically, a laser beam for alignment is emitted, the reflected light is detected to specify the position of the marker, and the position of the specified marker is corrected to determine the position of the phototransistor to be irradiated. It was specified and irradiated with a laser.

FIG. 2 shows a schematic explanatory view of a method of inspecting a circuit of an LCD substrate using a laser beam. In this figure, 4 is an LCD substrate, 5 is an inspection camera, 7a is a laser light source for a phototransistor on the X electrode side, 7b is a laser light source for a phototransistor on the y electrode side, and 9a is a photo provided on the X electrode side. Transistor row 9b indicates a phototransistor row provided on the Y electrode side.

To apply a voltage to the electrodes X1 and Y1, the phototransistors FX1 and FX2 shown in FIG. 1 are irradiated with laser beams. Although the light to be applied to the phototransistor is not limited to the laser beam, it is excellent in straightness when the installation interval of the irradiation target is very short and precise alignment is required as in this embodiment. It is preferable to use a laser beam, which makes it possible to accurately and easily irradiate only the phototransistor to which the beam is applied. A more detailed explanatory view of this inspection method is shown in FIG. This drawing is a view of FIG. 2 seen from above, and the laser light source 7B and the phototransistor array 9B for simplifying the explanation are omitted.

In FIG. 3, reference numeral 6 denotes a light source shade, which shields the laser beam 8 from the laser light source 7a so that the substrate 4 is not directly irradiated with the laser beam.
Reference numeral 10 is an LCD light source (backlight light source), 11 is a light source shade, and 12 is a backlight. In the initial state, all pixels are in a bright state (backlight is transmitted).

In FIG. 3, the laser light source 7a irradiates only the phototransistor (FX1 of FIG. 1) provided on the electrode X1 of the phototransistor array 9a with laser light, and at the same time, the laser light source 7B illuminates the phototransistor array 9B. Among them, when the laser is applied only to the phototransistor (FY1 in FIG. 1) provided on the electrode Y1, the voltage is applied only to the electrode X1 and the electrode Y1. No voltage is applied to the other electrodes (X2, X3 ..., Y2, Y3 ...).

In this case, if the circuit on the side of the electrode X1 and the circuit on the side of the electrode Y1 are both normal, only the pixel at the intersection thereof changes to the dark state (backlight does not pass). Therefore, it is possible to determine whether the circuit is normal or not by confirming whether or not the pixel at the intersection performs such normal operation. In this way, by checking whether or not the above-described normal operation is performed for all pixels by the laser light sources 7a and 7B, it is possible to inspect all circuits on the LCD.

When a laser beam is used, the intensity of the irradiation light and the irradiation position can be easily controlled, and the position control can be easily increased. In particular, as compared with the conventional method of aligning the inspection electrodes for each electrode, the alignment of the laser beam is very easy, and the problem of abrasion of the inspection electrodes does not occur. In addition, the conventional alignment method poses problems such as dust trapping and mechanical destruction of the electrodes,
Such a problem does not occur either.

Whether each pixel is operating normally is as follows.
It may be detected by any method. In the present embodiment, the inspection camera 5 monitors the image on the LCD panel at the time of inspection, and the image processing technology is used to confirm whether or not a predetermined pixel is operating normally in dark and light. And The position of the laser beam was also adjusted by image processing. At this time, if a mark for alignment is provided on the inspection electrode in advance, the alignment can be performed more easily. of course,
An operator or the like may directly confirm the operation of the pixel.

In this inspection method, it is necessary to form phototransistors on a substrate (LCD substrate in this embodiment) on which circuits are formed in advance, but normally, when manufacturing such a substrate, transistors, diodes, etc. are formed. It is necessary to form a considerable number, and in this case, the required number of phototransistors can be formed easily and at low cost. Therefore, it is not necessary to add new equipment or steps to form the phototransistor, and conventional equipment and steps can be used as they are.

Although the circuit of the LCD panel is inspected in this embodiment, the present invention is not limited to the LCD panel and is widely used for inspecting the circuit provided on the substrate such as the circuit of the PCB substrate. It is a thing. Further, although the TN type and STN type LCD panels have been illustrated in the above embodiments, an active matrix type (TFT type) LCD is used.
The same can be applied to. Especially in the active matrix system, each intersection of the X and Y electrodes (each pixel)
It is necessary to provide a switching element for each LC.
A phototransistor can be easily formed when forming this element on the D substrate. It is preferable to remove the phototransistor when the LCD substrate is shipped as a product, but in this embodiment, the phototransistor is formed at the end of each electrode, so the phototransistor is formed when the substrate is cut out. The phototransistor is easily removed by cutting out the non-existing region.

Usually, when commercializing an LCD substrate, a plurality of substrates are cut out from the original substrate. In such a conventional method, the phototransistor is automatically removed. Under normal usage conditions, it is not necessary to newly provide a phototransistor removing step. In the above embodiment, when each circuit has an abnormality, the result appears as a pixel light emission abnormality (so-called pixel defect). Further, even if there is no abnormality in the circuit, even if there is an abnormality in the liquid crystal of the pixel, the pixel causes an abnormality in light emission. Therefore, the method of inspecting the circuit in this embodiment can be performed as an inspection of the pixel itself or (an inspection of the LCD panel itself).

Although light is used as the electromagnetic wave in the above embodiments, X-rays, radio waves, magnetic force, etc. may be used. In this case, instead of the phototransistor, an element for generating an electromotive force in response to each medium is used. To use. Further, in the above-mentioned embodiment, the phototransistor is used as the member that generates electromotive force in response to light, but a photodiode, a photoelectric cell, a solar cell or the like may be used instead. Further, instead of the element that generates an electromotive force by the electromagnetic wave, a means whose resistance value changes by the electromagnetic wave may be used. In this case, all circuits should be energized in advance during normal operation, and during inspection,
An electromagnetic wave is applied to the resistance value changing means provided in the circuit to be inspected. As a result, the resistance value changes and the state of the circuit also changes. By detecting such a change, it is possible to determine whether or not there is an abnormality in the circuit. For example,
When the resistance value varying means is used in the configuration as in the above embodiment,
The change in the resistance value in the circuit is understood as the change in the brightness of the pixel.

[0031]

As described above, in the present invention, the circuit to be inspected can be inspected in a non-contact manner. Further, as compared with the conventional mechanical inspection method, positioning for specifying the inspection circuit is performed easily and quickly, and the problem that the inspection electrode is worn does not occur. Furthermore, the inspection of the LCD panel can be performed easily and quickly.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an LCD panel used in a circuit inspection method according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a circuit inspection method according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram of a circuit inspection method according to an embodiment of the present invention.

[Explanation of symbols]

 1, 4 LCD panel 2 Voltage control power supply 3 Variable resistance 5 Inspection camera 6 Laser shade 7, 8 Laser light source 9 Phototransistor 10 LCD light source 11 Light source shade 12 Backlight

Claims (6)

[Claims] 1. An electromotive force excitation element having a predetermined shape, wherein a plurality of circuit lines are formed on a circuit board for mounting an electronic circuit, and a predetermined portion of the circuit lines excites an electromotive force when an electromagnetic wave is detected. A circuit board characterized by being formed. 2. The circuit board according to claim 1, wherein the circuit board has an unnecessary area to be removed after the inspection, and the electromotive force excitation element is formed in the unnecessary area. 3. An LCD panel, wherein a photoelectric element that excites an electromotive force when sensing light is formed on a circuit line arranged corresponding to a pixel. 4. When forming an electronic circuit on a circuit board,
An electromotive force excitation element having a predetermined shape for exciting electromotive force when sensing an electromagnetic wave is previously connected to a predetermined portion of the electronic circuit,
At the time of inspecting the substrate, an electromagnetic wave is applied to the electromotive force excitation element corresponding to an electronic circuit to be inspected, which is a circuit inspection method. 5. In a manufacturing process of an LCD panel, a photoelectric element is previously electrically connected to a circuit line arranged corresponding to each pixel, and at the time of inspection of the LCD panel, a photoelectric element electrically connected to a pixel to be inspected. A method for inspecting an LCD panel, which comprises irradiating a light beam on the screen. 6. A marker corresponding to each photoelectric element is formed at a predetermined portion of the LCD panel, and when the light beam is irradiated, the irradiation direction of the light beam is specified using the marker as an index. 5. The LCD panel inspection method described in 5 or 6.