JPH05327153A - Wiring substrate and inspecting method thereof - Google Patents

Abstract

PURPOSE:To provide a wiring substrate capable of discriminating and making a judgement of the acceptability of the coated state of a conductive paste easily and satisfactorily regardless of the existence of minor defects in the wiring substrate and the inspecting method thereof. CONSTITUTION:Within this wiring substrate 1 wired of a conductive electrode film 3 whose terminal parts are coated with a conductive paste so as to be easily connected to outer lead pins 5, the conductive paste is mixed with a luminous body. In order to inspect the coated state of the conductive paste, the terminal parts are irradiated with a light so that the coated state may be inspected by discriminating the light emitted by the luminous body mixed with the conductive paste using a CCD camera.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring board in which wiring is provided on a substrate such as a liquid crystal display panel and a terminal portion thereof is coated with a conductive paste to connect external leads. More specifically, the present invention relates to a wiring board that makes it easier to inspect the application state of a conductive paste applied to the terminal portion, and an inspection method therefor.

[0002]

2. Description of the Related Art Conventionally, for example, on a glass substrate of a liquid crystal display element, each segment electrode and its lead wiring are formed of a transparent conductive film, a terminal portion is formed on a side edge portion of the glass substrate, and an external lead is provided via a lead pin. Electrically connected to. Therefore, in order to improve electrical contact between the lead pin and the conductive film, a conductive paste (carbon paste) is applied to the terminal portion by pin transfer or the like.

If the applied state of this conductive paste is not sufficient, the reliability of the electrical connection with the lead pin will be reduced, so the applied state is checked with a CCD camera or the like after application.
Only the good ones are inserted with lead pins and the conductive paste is dried. Then, a reinforcing material such as an ultraviolet curable resin is applied to the tip end portion of the lead pin and hardened, so that the lead pin is sufficiently electrically connected and fixed to the conductive film of each electrode terminal portion. As to the check of the application state of the conductive paste, as described above, the quality is judged by the shape and position of the recognized pattern by the recognition pattern by the reflected light by the CCD camera, for example. For example, as shown in FIGS. 5A and 5B, this recognition pattern has the same shape as the shape of the conductive paste because light is not absorbed and reflected only in the place where the conductive paste is applied. Pattern 14 is recognized. That is, FIG. 5A shows that a conductive paste is formed on the end of the conductive film 12 such as ITO formed on the glass substrate 11.
13 shows the applied state, and FIG. 5B shows the recognition pattern 14 recognized by the camera.

[0004]

According to the conventional method for inspecting the applied state of the conductive paste, when the surface of the glass substrate is smooth and there is no foreign matter as shown in FIG. Is recognized, and a pattern of the conductive paste as shown in FIG. 5B is obtained. However, if the surface of the glass substrate has a defect 15 such as a flaw or a chip as shown in FIG.
As shown in FIG. 5D, the recognition pattern by the CCD camera is a recognition including the patterns 17 and 18 of defects and foreign substances on the glass substrate, resulting in erroneous determination.

Defects such as flaws which cannot be visually confirmed on the glass substrate are practically no problem. However, it is not easy to check the presence or absence of these in advance by a CCD camera, and a good product is determined to be defective. However, there is a problem in that the recognition ability such as that of the conductive paste is deteriorated, and the determination of the application status of the conductive paste is erroneously determined.

The object of the present invention is to solve the above problems and to solve the above problems regardless of the presence or absence of subtle defects in a wiring substrate such as a glass substrate.
It is an object of the present invention to provide a wiring board and a method of inspecting the wiring board, which enables easy and good recognition of the coating state of the conductive paste.

[0007]

A wiring board according to the present invention is a wiring board in which a conductive electrode film is formed on a surface, and a conductive paste is applied to a terminal portion of the conductive electrode film to facilitate connection with an external lead. It is characterized in that a light emitting body which emits light by ultraviolet rays is mixed in the conductive paste.

Further, in the liquid crystal display device according to the present invention, each segment electrode of the liquid crystal display device and their electrode wiring are formed of a transparent conductive film on a glass substrate, and a conductive paste is applied to the terminal portion of the transparent conductive film. A liquid crystal display element having a glass substrate according to claim 1, wherein the conductive paste is mixed with a luminous body that emits light by ultraviolet rays.

Further, in the method for inspecting a wiring board according to the present invention, a conductive electrode film is formed on the surface of the wiring board, and a wiring board for inspecting the application state of the conductive paste applied to the terminal portion of the conductive electrode film is inspected. An inspection method is characterized in that a light emitting body that emits ultraviolet rays is mixed into the conductive paste, and the conductive paste is inspected by a CCD camera while irradiating ultraviolet rays having a wavelength suitable for the light emitting body.

[0010]

According to the present invention, since the conductive paste applied to the terminal portion is mixed with the luminous body such as a fluorescent body that emits light by ultraviolet rays, when the ultraviolet rays are radiated from the camera, the light is emitted from only the conductive paste. Is emitted, and only the applied state of the conductive paste can be inspected without being affected by the state of the surface of the wiring substrate such as scratches and foreign substances on other glass substrates. As a result, the applied state of the conductive paste can be accurately and easily determined, and erroneous determination can be prevented. In addition, the conductivity is not lowered by adjusting the mixing ratio of the light emitting body.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a wiring board of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view showing a state in which lead pins are fixed to a glass substrate of a liquid crystal display device according to an embodiment of the present invention, FIG. 2 is a sectional view of the device of FIG. 1 with a part thereof omitted, and FIG. Explanatory drawing of an assembly process for forming a substrate of a liquid crystal display device of the invention,
FIG. 4 is an explanatory view showing a recognition pattern of the conductive paste according to the embodiment of the present invention.

In the substrate of the liquid crystal display element shown in FIGS. 1 and 2, each segment electrode of the liquid crystal display element and the transparent conductive electrode film 3 of its wiring are formed on a glass substrate 1, and a second opposing electrode is formed on the upper surface thereof. The glass substrate 2 is arranged. Each transparent conductive electrode film 3 is led out to the side edge portion of the glass substrate 1, and a conductive paste 4 is applied to electrically connect the lead pin 5 to the terminal portion 3a. Although the present invention is characterized by the conductive paste 4, the assembly of the substrate of the liquid crystal display element will be described with reference to FIG.

First, each electrode film such as a segment electrode and its wiring film are formed on the glass substrate 1 by a vapor deposition method and patterning with a transparent conductive electrode film 3 such as ITO, and its terminal portion 3a is a side edge portion of the glass substrate 1. The second glass substrate 2 which is led out to the upper side of the glass substrate 1 and is opposed to the glass substrate 1 is arranged. An ultraviolet excitation type phosphor such as ZnS: Cu (representing ZnS doped with Cu, the same applies hereinafter) is used as a conductive material such as carbon paste in which carbon is pasted with a solvent such as butyl cellosolve for the terminal portion 3a. Apply the conductive paste 4 mixed within 20% (Fig. 3)
(A)). This application is performed by a screen printing method or the like. Next, the coated state of the conductive paste 4 is inspected by the CCD camera (FIG. 3 (b)). This inspection method is characterized and will be described in detail later. Next, when the desired coating state is obtained, the lead pin 5 having a substantially C-shaped cross section formed by the lead frame is sandwiched at the place where the conductive paste 4 is coated, and the conductive paste is dried. (FIG. 3 (c)). The lead pin 5 is the lead portion 5
The lead portions 5a are connected to each other by a tie bar 8 (FIG. 3 (d)). Next, a reinforcing material 9 such as an ultraviolet curable resin is applied to the portion sandwiched by the lead pins 5 to cure the reinforcing material 9 and then the tie bar 8
And the lead portion 5a are separated, and the electrical characteristics are inspected (FIG. 3 (e)).

In the method for inspecting the applied state of the conductive paste according to the present embodiment, since the ultraviolet-excitable phosphor within 20% by weight is mixed in the conductive paste, the conductive paste application section is kept in a dark room. When an image of the conductive paste application part is taken with a CCD camera while irradiating the surface with ultraviolet rays, as shown in FIG. 4A, defects such as chips and scratches are formed on the surface of the glass substrate.
If there is, or even if the foreign matter 16 adheres to the glass substrate, the substrate defect 15 and the foreign matter 16 are not recognized, and only the conductive paste can be recognized. As a result, as shown in FIG. 4B, only the applied state of the conductive paste can be accurately recognized as a pattern, and the flow of the process does not stop due to scratches and foreign matter that do not hinder practical use.

As the phosphor, for example, ZnS: Cu, Z
nO: Zn or the like can be used, which is excited by ultraviolet rays to emit light and can be recognized by a CCD camera. In addition, a specific color such as ZnS: Cu (for example,
It is also possible to use a phosphor that emits green light. In this case, the conductive paste can be recognized by using a filter corresponding to the emission color on the camera side (for example, a blue filter when the emission color is red). In this case, the accuracy of recognition is further improved.

In the above description, the fluorescent substance by irradiation of ultraviolet rays has been described, but any fluorescent substance that emits normal light other than ultraviolet rays and can be recognized by the camera may be used. Further, in the above example, the conductive paste formed on the terminal portion of the conductive film formed on the glass substrate of the liquid crystal display element has been described, but not limited to the liquid crystal display element, the conductive paste is applied on a printed circuit board or the like. The present invention can be similarly applied to the above.

[0018]

As described above, according to the present invention, since the luminous body is mixed in the conductive paste, minute defects such as chips and scratches on the surface of the wiring board and adhesion of foreign matter are not recognized. Only the conductive paste application part in which the luminous body is mixed is recognized. As a result, the conductive paste application portion of the wiring board can be accurately and quickly inspected, and the yield is not reduced due to minute defects that are practically problem-free, and the manufacturing cost of the electronic device as a whole can be reduced. ..

[Brief description of drawings]

FIG. 1 is a perspective view showing a state in which lead pins are fixed to a glass substrate of a liquid crystal display element that is an embodiment of the present invention.

2 is a partially omitted cross-sectional view of the apparatus of FIG.

FIG. 3 is an explanatory diagram of a manufacturing process of the substrate unit in FIG. 1.

FIG. 4 is an explanatory diagram showing a recognition pattern of a conductive paste which is an embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a recognition pattern of a conventional conductive paste.

[Explanation of symbols]

 1 Glass substrate 3 Conductive electrode film 3a Terminal part 4 Conductive paste 5 Lead pin

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H05K 3/32 B 9154-4E

Claims (3)

[Claims] 1. A wiring board having a conductive electrode film formed on a surface thereof, wherein a terminal portion of the conductive electrode film is coated with a conductive paste to facilitate connection with an external lead, the conductive paste emitting light by ultraviolet rays. A wiring board comprising a luminous body mixed therein. 2. A liquid crystal display device having a glass substrate on which a segment electrode of the liquid crystal display device and electrode wirings thereof are formed of a transparent conductive film on a glass substrate, and a conductive paste is applied to a terminal portion of the transparent conductive film. A liquid crystal display element, wherein a light-emitting body that emits ultraviolet light is mixed in the conductive paste. 3. A method of inspecting a wiring board, wherein a conductive electrode film is formed on a surface of the wiring board, and a coating state of the conductive paste applied to a terminal portion of the conductive electrode film is inspected. Is mixed with a luminous body that emits ultraviolet light,
A method for inspecting a wiring board, which comprises inspecting with a CCD camera while irradiating an ultraviolet ray having a wavelength suitable for the light emitter.