JPH09281520A - Method for connecting circuit board, liquid crystal display device and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a connection defect and to improve temp. characteristics by press bonding the input terminals of a liquid crystal panel and the output terminals of a circuit board by using a press bonding head having press bonding surfaces of a rugged state in the state of arranging both terminals opposite to each other via an adhesive layer. SOLUTION: The press bonding parts of the liquid crystal panel 18 and the circuit board 19 are arranged on a receiving base 15 and are press bonded by using the press bonding head 1 having the press bonding surfaces 25, 26 of the rugged shape in the state of arranging the input terminals 14 of the liquid crystal panel 18 and the output terminals of the circuit board 19 via the adhesive layer. The input terminals 14 and the output terminals are electrically connected. The adhesive layer consists substantially of the adhesive alone and conductive particles are not added thereto. A thermosetting adhesive consisting of an epoxy resin, etc., is used as the adhesive in the case of press bonding by thermosetting. A transparent receiving base consisting of quarts glass, etc., is used as the receiving base 15 and a photosetting adhesive is used as the adhesive in the case of press bonding by photosetting. A tape 2 for preventing the adhesion of stains is inserted at need between the parts to be press bonded and the press bonding head 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board connecting method, a liquid crystal display device, and an electronic apparatus.

[0002]

2. Description of the Related Art The background art of the present invention will be described with reference to FIGS.

The liquid crystal display device 24, as shown in FIG.
A liquid crystal panel 18 in which a liquid crystal layer 13 is arranged between two substrates 7 and 8, and a circuit board 1 for driving the liquid crystal panel 18.
9 and. The circuit board 19 has a semiconductor chip 4 for driving a liquid crystal and the like on the board. The liquid crystal panel 18 and the circuit board 19 are electrically connected to each other between the input terminal 14 of the liquid crystal panel 18 and the output terminal 5 of the circuit board 19.

Conventionally, as shown in FIG. 7, a liquid crystal panel 1 is used.
The input terminal 14 and the output terminal 5 of the circuit board 19 are electrically connected to each other by crimping the input terminal 14 and the output terminal 5 of the circuit board 19 with the adhesive layer 30 interposed therebetween. The crimping is performed by disposing the crimping portions of the liquid crystal panel 18 and the circuit board 19 on the pedestal 15 and applying pressure from the crimping head 20. The adhesive layer 30 contains the adhesive 21 and the conductive particles 22, and the conductive particles 22 electrically connect the input terminal 14 of the liquid crystal panel 18 and the output terminal 5 of the circuit board 19 as shown in FIG. And the liquid crystal panel 18 and the circuit board 1 by the adhesive 21.
9 and 9 are mechanically connected. A dirt adhesion prevention tape 2 is inserted between the pressure-bonded portion and the pressure-bonding head 1 as required.

[0005]

However, in the above-mentioned prior art, during crimping, as shown in FIGS. 8 to 11, the device is sandwiched between the input terminal 14 of the liquid crystal panel 18 and the output terminal 5 of the circuit board 19. In the open portion, the pressure is concentrated on the conductive particles 22, so that a crack or a crack (hereinafter, referred to as a “crack”) 23 around the conductive particles on the input terminal 14 is formed.
There is a problem in that the electric current is generated and the conduction is obstructed. In this case, it is conceivable that the pressure bonding is carried out at a low pressure so as not to cause the crack 23, but then, the input terminal 14 of the liquid crystal panel 18 and the output terminal 5 of the circuit board 19 are carried out.
The distance between the terminals of the liquid crystal display device becomes longer, and if it is stored or used at a high temperature, thermal expansion of the adhesive 21 may cause an electrical connection failure, which may cause deterioration in temperature characteristics of the liquid crystal display device 24. Therefore, it is not preferable.

Further, when the circuit board 19 is replaced due to a defect of the liquid crystal driving semiconductor 4 or the like, there is a problem that the crack 23 may cut the input terminal 14 itself of the liquid crystal panel 18. It was

Therefore, the present invention has been made in order to solve the above-mentioned problems, and its purpose is to reduce the temperature characteristics of the liquid crystal display device 24 to the input terminal 14 of the liquid crystal panel 18. A circuit for suppressing the generation of cracks 23 at the connection portion of the circuit board 19 with the output terminal 5 due to pressure bonding to ensure electrical continuity, and for manufacturing a replaceable liquid crystal display device 24 of the circuit board 19. It is to provide a method of connecting substrates.

It is another object of the present invention to provide a liquid crystal display device 24 which has no bad connection and good temperature characteristics, and a liquid crystal display device 24 in which the circuit board 19 can be replaced.

A further object of the present invention is to provide highly reliable electronic equipment using such a liquid crystal display device 24.

[0010]

Means for Solving the Problems A first invention of the present invention is:
A circuit board for electrically connecting the input terminal 14 and the output terminal 5 by crimping the input terminal 14 of the liquid crystal panel 18 and the output terminal 5 of the circuit board 19 in a state of being opposed to each other via the adhesive layer 27. In the connection method, the crimping is performed by using the crimping head 1 having the uneven crimping surface.

Since such a method is used, the output terminal 5
Is pressed by the pressure bonding head 1 to be deformed, and has an uneven shape corresponding to the uneven shape of the pressure bonding head 1. Then, at the convex portion 28 of the output terminal 5, the input terminal 14 and the output terminal 5 are in direct contact with each other, and electrical connection is secured. On the other hand, in the recess 29 of the output terminal 5, the input terminal 14 and the output terminal 5 are mechanically and firmly coupled to each other via the adhesive layer 27. As a result, it is possible to suppress the generation of the cracks 23 generated by the conventional method using the conductive particles, and without deteriorating the temperature characteristics of the liquid crystal display device 24, the output of the input terminal 14 of the liquid crystal panel 18 and the circuit board 19. It is possible to achieve the purpose of suppressing the occurrence of the crack 23 due to the pressure bonding at the connection portion with the terminal 5 and ensuring electrical continuity. Further, as a result, it is possible to prevent disconnection of the input terminal 14 due to the crack 23.
The purpose of manufacturing 9 replaceable liquid crystal display devices 24 can be achieved.

Further, in the above-mentioned method of connecting circuit boards, the size of φ30 to 60 μm (height 10 to 2) on the crimping surface.
It is characterized in that the pressure bonding is performed using the pressure bonding head 1 having the convex portion 25 of 0 μm).

Since such a method is used, the conductive particles 3
The pressure bonding force is concentrated on the wire 1, so that cracks or cracks 23 are formed around the conductive particles on the input terminal 14 to prevent the conduction from being hindered.

In the circuit board connecting method described above, when the area of the convex portion 25 of the pressure bonding head 1 is a and the area of the concave portion (26) of the pressure bonding head 1 is b,
/ (A + b) is 20 to 40%.

Since such a method is used, the contact area can be increased and the resistance value can be reduced and stabilized.

A second aspect of the present invention is a liquid crystal display device in which an input terminal 14 of a liquid crystal panel 18 and an output terminal 5 of a circuit board 19 are in contact with each other and electrically connected to each other. Has an uneven shape, the convex portion 28 and the input terminal 14 are directly connected to each other, and the concave portion 2
9 and the input terminal 14 are connected via an adhesive 27.

With this structure, the adhesive layer 30 contains the adhesive 21 and the conductive particles 22 for the conventional bonding by the anisotropic conductive film, but the dispersibility of the conductive particles in the adhesive, etc. This has the effect of eliminating the need for consideration.

Further, in the above liquid crystal display device, the convex portion 28 on the surface of the output terminal 5 has a size of 25 to 60 μm (a vertical height of 10 μm).

With this structure, the volume of the adhesive 16 can be reduced more than ever before.

Further, in the above liquid crystal display device, the area of the region where the output terminal 5 and the input terminal 14 are directly connected is defined as c, and the output terminal 5 and the input terminal 14 are bonded via an adhesive. The area of the area connected by
Then, c / (c + d) is 60 to 80%.

With this structure, it is possible to reduce the volume and area of the adhesive, and it is possible to provide a liquid crystal display device in which parts can be easily replaced.

In the above liquid crystal display device, the base material 3 carrying the output terminal 5 has a thickness of 20 to 50.
It is characterized by being a substrate having a thickness of μm. .

With this structure, when the temperature of the adhesive layer 27 is increased during pressure bonding, the head 1 on the heat supply side is provided.
Alternatively, the setting temperature of the pedestal 15 on the preheating side can be set to a lower temperature than before, so that the polarizing plates 10/11/12 sheets can be set.
This has the effect of reducing the effect of radiant heat on the adhesive agent 9 and the like.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the drawings.

[Embodiment 1] A pressure bonding step in this embodiment will be described with reference to FIG. Liquid crystal display device 24 of the present embodiment
As shown in FIG. 6, the liquid crystal layer 1 is provided between the two base materials 7 and 8.
And a liquid crystal panel 18 on which the liquid crystal panel 3 is arranged.
And a circuit board 19 for driving.

The base materials 7 and 8 of the liquid crystal panel have a thickness of 100 μm.
Is a PC (polycarbonate) film. This PC
The film substrate is an adhesive (sealant) containing a spacer agent
Held by 9. The liquid crystal panel 18 is the polarizing plate 1.
0 and 11 and a reflector or a semi-transmissive reflector 12.
ITO (Indium Tin Oxide) is formed on each surface of the substrates 7 and 8 by low temperature vapor deposition and then patterned.
de) transparent electrode pattern is formed. The end portion is the input terminal 14.

The circuit board 19 has a semiconductor chip 4 for driving liquid crystal on the board, and is also called TCP. An output terminal 5 is formed corresponding to the input terminal 14 of the liquid crystal panel 18. In this embodiment, a copper foil pattern is used as the output terminal 5. The output terminal 5 is laminated on the base material 3 made of a polyimide film.

It is necessary that the liquid crystal panel 18 and the circuit board 19 be electrically connected between the input terminal 14 of the liquid crystal panel 18 and the output terminal 5 of the circuit board 19. In this embodiment, as shown in FIG. 1, the input terminal 14 of the liquid crystal panel 18 is
The input terminal 14 and the output terminal 5 are electrically connected to each other by pressing the input terminal 14 of the circuit board 19 and the output terminal 5 of the circuit board 19 with the adhesive layer 27 in between, and pressing the input terminal 14 and the output terminal 5 with each other. Connected to. The crimping is performed by disposing the crimping portions of the liquid crystal panel 18 and the circuit board 19 on the pedestal 15 and applying pressure from the crimping head 1 thereon. The adhesive layer 27 is substantially made of only an adhesive and no conductive particles are added. As the adhesive, a thermosetting adhesive composed of an epoxy resin, an acrylic resin, polyurethane, or a mixture thereof can be used when pressure-bonding is performed by thermosetting. In the case of pressure bonding by means of a), a photocurable adhesive can be used. When pressure-bonding by photo-curing, it is preferable to use a transparent pedestal such as quartz glass as the pedestal 15. Crimped part and crimping head 1
If necessary, for example, a heat-resistant nitoflon tape is inserted as a dirt adhesion preventing tape 2 between and.

When such a method is used, FIGS.
As shown in, the output terminal 5 is connected to the crimping head 1 during crimping.
It is pressed and deformed to have an uneven shape corresponding to the uneven shape of the pressure bonding head 1. As a result, at the convex portion 28 of the output terminal 5, the input terminal 14 and the output terminal 5 are in direct contact with each other, and electrical connection is secured. On the other hand, in the recess 29 of the output terminal 5,
The input terminal 14 and the output terminal 5 are mechanically and firmly coupled to each other via the adhesive layer 27. Therefore, the crack 23 is not formed.
Therefore, it is possible to suppress the generation of the crack 23 at the connection portion between the input terminal 14 of the liquid crystal panel 18 and the output terminal 5 of the circuit board 19 and secure the conduction without deteriorating the temperature characteristic of the liquid crystal display device 24. You can Further, the liquid crystal display device 24 in which the circuit board 19 can be replaced can be manufactured without disconnecting the input terminal 14 due to cracks.

FIG. 2 is an enlarged cross-sectional view of the circuit board 19 of this embodiment at the time of crimping. FIG. 3 is a circuit board 19 of this embodiment.
3 shows the contact area in the transparent electrode pattern of FIG.

The shaded portion in the figure is the contact portion between the transparent electrode pattern and the copper foil, where electrical connection is secured.

FIG. 4 shows the overall appearance of the circuit board 19 of this embodiment.

[Embodiment 2] The pressure bonding step in this embodiment will be described with reference to FIG. Liquid crystal display device 24 of the present embodiment
As shown in FIG. 6, the liquid crystal layer 1 is provided between the two base materials 7 and 8.
And a liquid crystal panel 18 on which the liquid crystal panel 3 is arranged.
And a circuit board 19 for driving.

The base materials 7 and 8 of the liquid crystal panel have a thickness of 100 μm.
Is a PC (polycarbonate) film. This PC
The film substrate is an adhesive (sealant) containing a spacer agent
Held by 9. The liquid crystal panel 18 is the polarizing plate 1.
0 and 11 and a reflector or a semi-transmissive reflector 12.
ITO (Indium Tin Oxide) is formed on each surface of the substrates 7 and 8 by low temperature vapor deposition and then patterned.
de) transparent electrode pattern is formed. The end portion is the input terminal 14.

The circuit board 19 has a semiconductor chip 4 for driving liquid crystal on the board, and is also called a TCP. An output terminal 5 is formed corresponding to the input terminal 14 of the liquid crystal panel 18. In this embodiment, a copper foil pattern is used as the output terminal 5. The output terminal 5 is laminated on the base material 3 made of a polyimide film.

It is necessary that the liquid crystal panel 18 and the circuit board 19 be electrically connected to each other between the input terminal 14 of the liquid crystal panel 18 and the output terminal 5 of the circuit board 19. In this embodiment, as shown in FIG. 1, the input terminal 14 of the liquid crystal panel 18 is
The input terminal 14 and the output terminal 5 are electrically connected to each other by crimping them with the crimping head 1 having an uneven crimping surface in a state where the and the output terminal 5 of the circuit board 19 are arranged via the adhesive layer 27. Connected to. The crimping is performed by disposing the crimping portions of the liquid crystal panel 18 and the circuit board 19 on the pedestal 15 and applying pressure from the crimping head 1 thereon. The adhesive layer 27 is substantially made of only an adhesive and no conductive particles are added. As the adhesive, a thermosetting adhesive made of an epoxy resin, an acrylic resin, polyurethane, or a mixture thereof can be used when pressure-bonding by thermosetting, and is cured by light or ultraviolet light (hereinafter, photocuring). In the case of pressure bonding by means of a), a photocurable adhesive can be used. When pressure-bonding by photo-curing, it is preferable to use a transparent pedestal such as quartz glass as the pedestal 15. Crimped part and crimping head 1
If necessary, for example, a heat-resistant nitoflon tape is inserted as a dirt adhesion preventing tape 2 between and.

The contact surface of the pressure bonding head 1 is changed from a flat surface to a tool having a plurality of spherical projections having a height of about 20 μm and a pitch of about 0.17 mm, and the contact area between the copper foil on the TCP side and the transparent electrode pattern. Is larger than the conventional ball-shaped particles having a diameter of about 10 μm for electrical conduction to prevent pressure from concentrating and to secure electrical connection, thereby generating cracks on the transparent electrode pattern. It is possible to prevent the disconnection of the circuit. In addition, an adhesive material is filled in a portion that becomes the tool concave portion to secure mechanical connection and strength capable of withstanding aging. By increasing the contact area, the connection resistance can be reduced and stability can be secured, and at the same time, the volume of the adhesive can be reduced by the amount that the volume of the convex portion of the spherical convex head is increased as compared with the volume of the conventional conductive particles.

The adhesive used is a styrene-butadiene-styrene (SBS) type, an epoxy type, an acrylic type, a polyester type, a urethane type or the like, or a mixture or compound of some of them. Here, unlike the conventional anisotropic conductive film, since conductive particles plated in the adhesive are not included, it is not necessary to consider the dispersibility of the particles.

FIG. 2 is an enlarged cross-sectional view of the circuit board 19 of this embodiment at the time of crimping. FIG. 3 is a circuit board 19 of this embodiment.
3 shows the contact area in the transparent electrode pattern of FIG.

The shaded area in the figure is the contact area between the transparent electrode pattern and the copper foil, where electrical connection is secured.

FIG. 4 shows the overall appearance of the circuit board 19 of this embodiment.

[Embodiment 3] The pressure bonding step in this embodiment will be described with reference to FIG. Liquid crystal display device 24 of the present embodiment
As shown in FIG. 6, the liquid crystal layer 1 is provided between the two base materials 7 and 8.
And a liquid crystal panel 18 on which the liquid crystal panel 3 is arranged.
And a circuit board 19 for driving.

The base materials 7 and 8 of the liquid crystal panel have a thickness of 100 μm.
Is a PC (polycarbonate) film. This PC
The film substrate is an adhesive (sealant) containing a spacer agent
Held by 9. The liquid crystal panel 18 is the polarizing plate 1.
0 and 11 and a reflector or a semi-transmissive reflector 12.
ITO (Indium Tin Oxide) is formed on each surface of the substrates 7 and 8 by low temperature vapor deposition and then patterned.
de) transparent electrode pattern is formed. The end portion is the input terminal 14.

The circuit board 19 has a semiconductor chip 4 for driving liquid crystal on the board, and is also called TCP. An output terminal 5 is formed corresponding to the input terminal 14 of the liquid crystal panel 18. In this embodiment, a copper foil pattern is used as the output terminal 5. The output terminal 5 is laminated on the base material 3 made of a polyimide film.

It is necessary that the liquid crystal panel 18 and the circuit board 19 be electrically connected between the input terminal 14 of the liquid crystal panel 18 and the output terminal 5 of the circuit board 19. In this embodiment, as shown in FIG. 1, the input terminal 14 of the liquid crystal panel 18 is
The input terminal 14 and the output terminal 5 are electrically connected to each other by pressing the input terminal 14 of the circuit board 19 and the output terminal 5 of the circuit board 19 with the adhesive layer 27 in between, and pressing the input terminal 14 and the output terminal 5 with each other. Connected to. The crimping is performed by disposing the crimping portions of the liquid crystal panel 18 and the circuit board 19 on the pedestal 15 and applying pressure from the crimping head 1 thereon. The adhesive layer 27 is substantially made of only an adhesive and no conductive particles are added. As the adhesive, a thermosetting adhesive composed of an epoxy resin, an acrylic resin, polyurethane or the like or a mixture thereof can be used when pressure-bonding by heat curing, and when pressure-bonding by light or light curing. Can use a photocurable adhesive. When pressure-bonding by photo-curing, it is preferable to use a transparent pedestal such as quartz glass as the pedestal 15. If necessary, for example, a heat-resistant Nitoflon tape is inserted between the pressure-bonded portion and the pressure-bonding head 1 as the dirt adhesion preventing tape 2.

Polyimide, Upilex, etc. are usually used as the base material of TCP, but the thickness of the base material is made as thin as 25 .mu.m in order to cope with the irregularities of the thermocompression bonding head 1, or it has a flexible property. You may change it to the one you have. If the curing condition of the adhesive is made the same as the conventional one by reducing the thickness of the base material, the set temperature of the heating heater etc. can be set low, and the temperature of the adhesive 27 is raised during pressure bonding. In addition, since the set temperature of the head 1 on the heat supply side or the pedestal 15 on the preheating side can be set to a lower temperature than before, the influence of radiant heat exerted on the polarizing plates 10/11/12 seal agent 9 and the like can be reduced.

FIG. 2 is an enlarged cross-sectional view of the circuit board 19 of this embodiment at the time of crimping, and FIG. 3 is a circuit board 19 of this embodiment.
3 shows the contact area in the transparent electrode pattern of FIG.

The shaded portion in the figure is the contact portion between the transparent electrode pattern and the copper foil, where electrical connection conduction is secured.

FIG. 4 shows the overall appearance of the circuit board 19 of this embodiment.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a pressure bonding step in one embodiment of the present invention.

FIG. 2 is a sectional view showing a main part of a liquid crystal display device according to one embodiment of the present invention.

FIG. 3 is an enlarged explanatory view showing a crimping process in one embodiment of the present invention.

FIG. 4 is a main cross-sectional view showing a main part of a liquid crystal display device according to one embodiment of the present invention.

FIG. 5 is an enlarged cross-sectional view showing a main part of a liquid crystal display device according to an embodiment of the present invention.

FIG. 6 is an overall view of the present invention and a conventional liquid crystal display device.

FIG. 7 is an explanatory view showing a conventional pressure bonding step.

FIG. 8 is a sectional view showing a main part of a conventional liquid crystal display device.

FIG. 9 is an enlarged explanatory view showing a conventional pressure bonding step.

FIG. 10 is a main cross-sectional view showing a main part of a conventional liquid crystal display device.

FIG. 11 is an enlarged perspective view showing a main part of a conventional liquid crystal display device.

[Explanation of symbols]

 1 Crimping Head 2 Contamination Prevention Tape 3 Output Terminal Support Substrate 4 Liquid Crystal Driving Semiconductor Chip 5 Circuit Board Output Terminal 6 Liquid Crystal Driving Semiconductor Chip Active Surface Protection Mold 7 For Flexible Liquid Crystal Panel Base material 8 Flexible base material for liquid crystal panel 9 Sealing agent 10 Polarizing plate 11 Polarizing plate 12 Reflecting plate or semi-transmissive reflecting plate 13 Liquid crystal 14 Liquid crystal panel input terminal 15 Receptacle 16 Adhesive 17 Electrical contact Area 18 Liquid crystal panel 19 Circuit board 20 Crimping head (conventional type) 21 Adhesive 22 Conductive particles 23 Crack 24 Liquid crystal display 25 Crimping head protrusion 26 Crimping head recess 27 Adhesive layer 28 Output terminal protrusion 29 Output terminal Recessed portion 30 Adhesive layer of anisotropic conductive film

Claims (8)

[Claims] 1. A connection of a circuit board for electrically connecting the input terminal and the output terminal by crimping the input terminal of the liquid crystal panel and the output terminal of the circuit board so as to face each other with an adhesive layer in between. In the method, the circuit board connection method is characterized in that the pressure bonding is performed using a pressure bonding head having an uneven pressure bonding surface. 2. The method for connecting circuit boards according to claim 1, wherein the pressure bonding surface has a size of φ30 to 60 μm (height of 10 to 20 μm).
A method of connecting circuit boards, characterized in that crimping is performed using a crimping head having a convex portion of m). 3. The circuit board connecting method according to claim 1, wherein a / (a + b) is 20 to 20, where the area of the convex portion of the pressure bonding head is a and the area of the concave portion of the pressure bonding head is b.
40% is a circuit board connection method characterized by being 40%. 4. A liquid crystal display device in which an input terminal of a liquid crystal panel and an output terminal of a circuit board are electrically connected via an adhesive layer, wherein the surface of the output terminal has an uneven shape, The liquid crystal display device is characterized in that the section and the input terminal are directly connected, and the recess and the input terminal are connected via an adhesive. 5. The liquid crystal display device according to claim 4, wherein the convex portion on the surface of the output terminal 5 has a size of φ30 to 60 μm (height 10 to 20 μm). 6. The liquid crystal display device according to claim 4, wherein an area of a region where the output terminal and the input terminal are directly connected to each other is c, and the output terminal and the input terminal are interposed by an adhesive. A liquid crystal display device, wherein c / (c + d) is 60 to 80% when the area of the connected region is d. 7. The liquid crystal display device according to claim 4, wherein the base material carrying the output terminal has a thickness of 20 to 50 μm.
A liquid crystal display device, characterized in that the substrate is m. 8. The liquid crystal display device according to claim 4, wherein the base material carrying the output terminal is a flexible base material.