JP2002006330A - Substrate for liquid crystal display device and method for mounting circuit on the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate for a reflection type liquid crystal display device in which the electrode pattern also acting as a reflector can be protected and on the peripheral part of which circuits can be easily mounted and a method for mounting circuits on the substrate. SOLUTION: The substrate is to be used for a reflection type liquid crystal display device manufactured by disposing a surface side electrode substrate having a transparent electrode pattern formed and a back electrode substrate having an electrode pattern with the electrode pattern facing the transparent electrode pattern through a liquid crystal. The back side electrode substrate has the electrode pattern of a metal film 14 having a reflective face to reflect light and conductivity on a glass substrate 11, and has a protective film 15 which transmits light on the surface of the metal film 14. A comb-like connecting part formed in the periphery of the glass substrate 11 has a protruding part 12' formed on the glass substrate 11 and the metal film 14 and the protective film 15 are formed on the protruding part 12'.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate suitable for a reflection type liquid crystal display device and a method for mounting a circuit on the substrate.

[0002]

2. Description of the Related Art Conventionally, a reflection type liquid crystal display device uses a reflection plate for utilizing external light. Unlike a transmission type liquid crystal display device having an illumination light source therein, power consumption is reduced. For example, it is used for a display device such as a calculator, a wristwatch, an electronic system organizer, or a mobile phone which operates with a dry cell or a solar cell. In such a reflection type liquid crystal display device, in which a reflection plate for reflecting external light is arranged on the back side of the back electrode substrate, a distance between the liquid crystal display and the reflection plate corresponds to a thickness of the back electrode substrate. However, the liquid crystal display is reflected as a shadow on the reflection plate, and the display is easily blurred. In particular, when the miniaturization or colorization of the liquid crystal display is advanced, the displayed image may be blurred and unclear. On the other hand, in recent years, an electrode pattern of a back electrode substrate constituting a liquid crystal display device has also been used as a reflector.

[0003]

In the conventional reflection type liquid crystal display device, when the electrode pattern of the back electrode substrate is also used as a reflection plate, it has a reflection surface capable of sufficiently reflecting light and has conductivity. As the material, for example, aluminum or an alloy of aluminum and silver is used. However, when an aluminum film is used alone as the electrode pattern, the surface of the aluminum film is oxidized and changes to aluminum oxide having insulating properties, making it difficult to mount a circuit. There is a problem that the yield is easily deteriorated in the manufacturing process. In addition, when aluminum or a silver alloy is used, the mounting portion may be easily corroded and the reflectance may be easily lowered in an environment after the circuit is mounted. Therefore, for example, when an aluminum film or an alloy film of aluminum or silver is used as an electrode pattern and a protective film such as a silicon oxide film is formed on the surface thereof, the yield can be improved in the manufacturing process, but the electrode pattern can be improved. Since the peripheral portion is also covered with a silicon oxide film having an insulating property, circuit mounting may be difficult.

[0004] The present invention has been made in view of the above circumstances,
An object of the present invention is to provide a substrate for a liquid crystal display device which can protect an electrode pattern which can also serve as a reflection plate as a substrate for a reflection type liquid crystal display device and can easily mount a circuit in a peripheral portion, and a circuit mounting method of the substrate.

[0005]

In order to achieve the above object, according to the first aspect of the present invention, an electrode pattern opposed to a transparent electrode pattern is formed on a front-side electrode substrate with a liquid crystal interposed therebetween. In the reflective liquid crystal display device substrate on which the formed back electrode substrate is arranged, the back electrode substrate has a reflective surface for reflecting light on a glass substrate and an electrode pattern of a conductive metal film is formed. A protective film that transmits light is formed on the surface of the metal film, and the circuit connection portion formed in a comb-like shape on the periphery of the glass substrate has the metal film and the protrusion on the glass substrate. And a protective film is formed. An electrode pattern of a metal film that can also serve as a reflection plate as a reflection type liquid crystal display device substrate can be protected by a protective film, so that the yield can be improved, and the circuit mounting at the periphery where the protrusions are formed can be facilitated.

According to a second aspect of the present invention, the metal film is made of aluminum, an aluminum alloy or a silver alloy, and the protective film is made of silicon oxide. is there. The protective film protects the metal film, improves the yield in the manufacturing process, and prevents oxidation and corrosion.

According to a third aspect of the present invention, there is provided a reflective liquid crystal display in which a back electrode substrate on which a facing electrode pattern is formed with a liquid crystal interposed is disposed on a front electrode substrate on which a transparent electrode pattern is formed. In the method for mounting a circuit on an apparatus substrate, a step of forming a projection on the surface of the glass substrate peripheral portion of the back electrode substrate, and a surface having a reflection surface for reflecting light on the surface of the glass substrate on which the projection is formed and having a conductive surface Forming a metal film to be an electrode having a property, forming a light-transmitting protective film on the surface of the metal film, and forming an electrode pattern by patterning the protective film and the metal film. Exposing a metal film on the protruding portion to the surface of the protective film, and forming a circuit having connection electrodes formed in a comb-like shape at the same interval as the electrode pattern on the exposed metal film using a conductive adhesive. It is characterized in that and a step of electrically connecting to. Since the metal film and the protective film on the protruding portion are formed in a protruding shape in the same shape, the metal film can be easily exposed, and the circuit mounting can be simplified.

According to a fourth aspect of the present invention, in the step of exposing the metal film to the surface of the protective film, the protective film on the protrusion is removed by a mechanical means. is there. The metal film is easily exposed by mechanical means, and circuit mounting is simplified.

According to a fifth aspect of the present invention, in the step of exposing the metal film on the surface of the protective film, the connecting electrode side of the circuit is pressed against the protective film on the protrusion, The film portion is damaged to expose the metal film. The metal film is easily exposed by crimping the connection electrode side of the circuit to the protective film on the protrusion, thereby simplifying the circuit mounting.

In the invention according to a sixth aspect, the projection is formed in a dot shape or a band shape. The metal film is exposed according to the shape of the projection, and the circuit mounting is simplified.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to an embodiment shown in the drawings. 1 to 3 are views for explaining a substrate for a liquid crystal display device and a circuit mounting method thereof according to an embodiment of the present invention. FIG. 1 is a cross-sectional view for explaining a manufacturing process of the substrate for a liquid crystal display device. FIG. 3 is a cross-sectional view showing a state in which a circuit is mounted on a device substrate, and FIG. 3 is a plan view showing a shape of a projection formed on a peripheral portion of the liquid crystal display device substrate.

As shown in FIG. 1A, first, an acrylic or synthetic rubber-based photosensitive resin is formed on the surface of a glass substrate 11 made of soda glass or the like constituting a back electrode substrate for a liquid crystal display device. Material or carbon, silver,
Using a spin coater or the like, a negative photoresist made of a photosensitive resin material having a paste-like conductivity containing a metal powder such as copper is coated with a resist film 12 to a uniform thickness of 0.5 to 20 μm, preferably about 2 to 6 μm. Form.

Next, as shown in FIG. 1B, exposure is performed using a photomask 13 for forming a projection on a circuit mounting portion on the periphery of the glass substrate 11, followed by development and printing of the pattern. A baking is performed to form a plurality of protrusions 12 'made of a soft resin material as shown in FIG. The protrusion 12 'has a cylindrical shape having an outer diameter of about 5 to 20 .mu., Preferably about 7 to 10 .mu., And a height of about 2 to 10 .mu., Preferably about 4 to 5 .mu. As shown in FIG. 5, the metal film 14 is formed in a portion corresponding to the metal film 14 which will be an electrode pattern in a later step. The projection 12 'is formed by a photolithography method using a negative photoresist or the like, but a positive photoresist can also be used. Alternatively, the projection 12' can be formed by a printing method such as offset printing or silk printing. Is also good.

Next, as shown in FIG.
On the surface of the glass substrate 11 on which 2 ′ is formed, for example,
A metal film 14 having a reflecting surface for reflecting light of aluminum, aluminum alloy, silver alloy or the like having a thickness of 200 to 2000 mm, preferably about 1000 mm and having conductivity is formed by vacuum evaporation, sputtering or CVD.
It is formed by a method or the like. The metal film 14 becomes a pattern electrode of a reflection type liquid crystal display device by forming a pattern later, and also has a role as a reflection plate.

Next, as shown in FIG.
On the surface of No. 4, for example, the thickness is about 50 to 2000 mm,
A protective film 15 preferably made of a transparent material such as silicon oxide (SiO2) having a thickness of about 200 ° is formed by a similar vacuum deposition method, sputtering method, CVD method, or the like. The protective film 15 can improve the yield in the liquid crystal cell manufacturing process by protecting the metal film 14 and has insulating properties. It has a function of preventing a short circuit between 14 and the pattern electrode provided on the facing surface electrode substrate. Subsequently, the metal film 14 and the protective film 15 are formed into an electrode pattern, for example, in a stripe shape by etching or the like. This electrode pattern is formed, for example, with a horizontal dimension of about 50 to 500 μ and a pattern interval dimension of about 5 to 30 μ.

Next, as shown in FIG. 1 (f), a surface electrode substrate having a transparent ITO electrode 31 formed on an opposite glass substrate 30 is disposed with a liquid crystal 32 interposed therebetween. Seal with. Then, a comb-like portion for circuit connection at the peripheral portion of the glass substrate 11 on which the protruding portion 12 ′ is formed is removed by, for example, mechanical means such as lightly polishing the surface, and the surface of the protective film 15 is removed. Lower metal film 1
4 is partially exposed, and in a portion where the metal film 14 is exposed, for example, a connection electrode 17 similarly formed in a comb shape on a film carrier 16 provided with a circuit is provided with a conductive adhesive 18. It is electrically connected by crimping with the crimping means 19 through the intermediary. This film carrier 18 is, for example,
Circuits such as a driving element (chip) (not shown) of a liquid crystal display device such as a semiconductor integrated circuit are bonded by a tape made of a material such as polyimide or polyester, and patterned by laminating copper. The conductive adhesive 18 is, for example, an anisotropic conductive adhesive containing metal particles and the like. The conductive adhesive 18 is applied to a portion where the metal film 14 is exposed, and the connection electrode 17 is crimped. 1
Heat treatment for about a minute. Through the above steps, the circuit can be mounted on the back electrode substrate of the liquid crystal display device as shown in FIG.

In the substrate for a liquid crystal display device having the above-described structure, a pattern of an electrode of a metal film 14 having a reflection surface for reflecting light on the surface of the glass substrate 11 and serving as a conductive electrode is formed. Protective film 15 that transmits light on top
Is formed, the electrode pattern of the metal film 14 functions as a reflector for reflecting external light as a reflective liquid crystal display device and as an electrode. Even if it is colorized, the displayed image does not blur and become unclear, and the structure can be simplified. In addition, the surface of the metal film 14 is made of silicon oxide (SiO 2).
Since the protective film 15 is formed, not only can the metal film 14 be protected and the yield in the manufacturing process can be improved, but also because of the insulating property of silicon oxide, the electrode of the metal film 14 can be formed even if there is dust in the liquid crystal. There is no short circuit between the transparent electrode pattern of the surface electrode substrate facing the pattern,
The step for applying the insulating film can be omitted.

In the circuit mounting method for a substrate for a liquid crystal display device having the above-described structure, a projection 12 'made of a resin material is formed on a peripheral portion of the surface of the glass substrate 11 where electrodes are connected, and the projection 12' is formed. Metal film 1 on the surface of glass substrate 11
4 and the protective film 15 are sequentially formed, so that the protrusion 1
Similarly, the metal film 14 and the protective film 15 on the 2 ′ are formed in a projecting shape, and the metal film 14 is easily exposed to the surface of the protective film 15 by removing the projecting portion by mechanical means such as polishing. Can be done. Therefore, this glass substrate 1
A portion of a connection electrode 17 connected to a circuit provided on the film carrier 16 via a conductive adhesive 18 is press-bonded to an exposed portion of the comb-shaped metal film 14 at a peripheral portion of the device 1 so as to be electrically connected. Connection can be easily performed, so that a drive circuit and the like can be easily mounted. In addition, if the protrusion 12 ′ is formed of a conductive resin material, the metal film 14 and the protrusion 12 ′ are formed.
Are electrically connected to each other, so that even if the metal film 14 is damaged and the projection 12 'is exposed, a circuit can be mounted on that portion.

4 to 6 are views for explaining another embodiment of the projection of the present invention. FIG. 4 is a plan view of the projection formed in a triangular cylinder, and FIG. 5 is a quadrilateral cylinder. FIG. 6 is a plan view of a projection formed in a band shape, and FIG. 6 is a plan view of a projection formed in a band shape. Note that parts or members corresponding to the above embodiment are denoted by the same reference numerals.

Each of the protrusion 21 shown in FIG. 4 and the protrusion 22 shown in FIG. 5 is formed in a dot shape with the same size and height as the protrusion 12 'of the above embodiment. 6 is formed in a band shape.

The projections 21 and 21 according to these embodiments
By forming the metal films 2 and 23 on the surface of the glass substrate 11 and forming the metal film 14 and the protective film 15 on the surface, the metal film 14 can be easily removed by removing the portions by mechanical means such as polishing. The surface of the protective film 15 can be exposed, and the exposed portion of the metal film 14 can be electrically connected to the exposed portion of the metal film 14 by pressing the connection electrode 19 through the conductive adhesive 18. Easy to implement.

In the above embodiment, the example in which the dot-shaped or band-shaped projections 12 ', 21, 22, 23 are formed has been described. However, at least the comb teeth for mounting the circuit on the peripheral portion of the glass substrate 11 are described. The shape is only an example, and the shape, size, and number of dots, or the width, height, and the number of strips can be arbitrarily determined. Also, the projections 12 ', 21, 22, 23
The upper protective film 15 is removed by mechanical means such as polishing to expose the metal film 14 on the surface of the protective film 15. For example, the connection electrode 17 is strongly pressed through the conductive adhesive 20. Then, the protective film 15 on the protrusions 12 ', 21, 22, 23 may be damaged and exposed. further,
In this embodiment, TAB (Tape Automated Bones) in which a semiconductor integrated circuit is bonded to the film carrier 18 is used.
Although the ding) method has been described as an example, a COG (Chip On Glass) method in which a bare semiconductor integrated circuit is directly mounted on the periphery of the substrate may be used. Although the protective film 15 is made of silicon oxide, another protective film having at least insulating properties may be used.

[0023]

As described above, in the substrate for a liquid crystal display device of the present invention, the back electrode substrate on which the facing electrode pattern is formed with the liquid crystal interposed is disposed on the front electrode substrate on which the transparent electrode pattern is formed. In the reflection-type liquid crystal display device substrate, the back-side electrode substrate has a reflective surface for reflecting light on a glass substrate, and an electrode pattern of a conductive metal film is formed on the surface of the metal film. A protective film that transmits light is formed, and a circuit connection portion formed in a comb-like shape at the periphery of the glass substrate is formed by forming the metal film and the protective film on a protrusion formed on the glass substrate. It is characterized by having. An electrode pattern of a metal film that can also serve as a reflection plate as a reflection type liquid crystal display device substrate can be protected by a protective film, so that the yield can be improved, and the circuit mounting at the periphery where the protrusions are formed can be facilitated.

In the method for mounting a circuit on a substrate of the present invention,
In a circuit mounting method for a reflection type liquid crystal display device substrate, in which a back electrode substrate on which a facing electrode pattern is formed with a liquid crystal interposed is disposed on a front electrode substrate on which a transparent electrode pattern is formed, A step of forming a projection on the surface of the peripheral portion of the substrate, and a step of forming a metal film to be a conductive electrode having a reflective surface for reflecting light on the surface of the glass substrate having the projection formed thereon, Forming a protective film that transmits light on the surface of the metal film;
Forming an electrode pattern by patterning the protective film and the metal film; exposing the metal film on the protrusion to the surface of the protective film; and forming a comb on the exposed metal film at the same interval as the electrode pattern. Electrically connecting a circuit having a connection electrode formed in a tooth shape via a conductive adhesive. Since the metal film and the protective film on the protruding portion are formed in a protruding shape in the same shape, the metal film can be easily exposed, and the circuit mounting can be simplified.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a manufacturing process of a liquid crystal display device substrate according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a state where a circuit is mounted on the liquid crystal display device substrate according to the embodiment of the present invention.

FIG. 3 is a plan view showing a shape of a protrusion formed on a peripheral portion of the liquid crystal display device substrate according to the embodiment of the present invention.

FIG. 4 is a plan view of a protrusion formed in a triangular cylindrical shape according to another embodiment of the present invention.

FIG. 5 is a plan view of a projection formed in a quadrangular cylindrical shape according to another embodiment of the present invention.

FIG. 6 is a plan view of a belt-shaped protrusion according to another embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 11 glass substrate 12 resist film 12 ′ protrusion 13 photomask 14 metal film 15 protective film 16 film carrier 17 connection electrode 18 conductive adhesive 21, 22, 23 protrusion 30 glass substrate 31 ITO electrode 32 sealing material

Claims (6)

[Claims] 1. A reflection type liquid crystal display device substrate comprising a front electrode substrate on which a transparent electrode pattern is formed and a rear electrode substrate on which a facing electrode pattern is formed with a liquid crystal interposed therebetween, wherein the rear electrode substrate is provided. An electrode pattern of a conductive metal film having a reflective surface for reflecting light on a glass substrate is formed, a protective film for transmitting light is formed on the surface of the metal film, and the periphery of the glass substrate is A substrate for a liquid crystal display device, wherein the circuit connection portion formed in a comb shape has the metal film and the protective film formed on a protrusion formed on the glass substrate. 2. The substrate for a liquid crystal display device according to claim 1, wherein said metal film is made of one of aluminum, an aluminum alloy and a silver alloy, and said protective film is silicon oxide. 3. A circuit mounting method for a reflection-type liquid crystal display device substrate, comprising: a front-side electrode substrate on which a transparent electrode pattern is formed, and a back-side electrode substrate on which a facing electrode pattern is formed with a liquid crystal interposed therebetween. Forming a protruding portion on the surface of the glass substrate peripheral portion of the back electrode substrate, and forming a metal film serving as a conductive electrode having a reflective surface for reflecting light on the surface of the glass substrate having the protruding portion formed thereon Forming a protective film that transmits light on the surface of the metal film, forming an electrode pattern by patterning the protective film and the metal film, and protecting the metal film on the protrusion. Exposing the surface of the film, the step of electrically connecting a circuit having a comb-shaped connection electrode at the same interval as the electrode pattern on the exposed metal film via a conductive adhesive, Circuit mounting method of a substrate for a liquid crystal display device, characterized in that it comprises. 4. The circuit according to claim 3, wherein the step of exposing the metal film to the surface of the protective film removes the protective film on the protrusion by mechanical means. Implementation method. 5. The step of exposing the metal film on the surface of the protective film, wherein the connection electrode side of the circuit is pressure-bonded to the protective film on the protrusion, and the compressed film portion is damaged to expose the metal film. 4. The method for mounting a circuit on a substrate for a liquid crystal display device according to claim 3, wherein: 6. The method according to claim 3, wherein the protrusion is formed in a dot shape or a band shape.