JP2001337340A - Liquid crystal display device, method of manufacture thereof, anisotropic conductive film, and external circuit mounting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device in which disconnections are reduced and which can perform stable liquid crystal display by reducing the crack of a connecting terminal due to conductive particles in an anisotropic conductive film when an external circuit is press-connected with the connecting terminal at the time of press-connection of the external circuit with the connecting terminal, such as an ITO connecting terminal, formed on a liquid crystal display panel using a plastic substrate where the anisotropic conductive film is used for press-connection. SOLUTION: The liquid crystal display device is manufactured by press- connecting the ITO connecting terminal 32 of the liquid crystal panel formed by using the plastic substrate 31 and a flexible substrate 33 via the anisotropic conductive film 21 formed by dispersing the conductive particles 11 each having a metal thin layer into an adhesive resin 12, where each conductive particle has <=73.0 MPa metal thin layer breaking stress, on a base material surface, by loading the one conductive particle with the breaking load of the metal thin layer or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connecting terminal formed on a liquid crystal display panel using a plastic substrate and a connecting terminal on a flexible substrate on which an LSI or the like is mounted as an external circuit. The present invention relates to a liquid crystal display device which is electrically connected (mounted) using a film, a method for manufacturing the same, an anisotropic conductive film used for the manufacture thereof, and a method for mounting an external circuit.

[0002]

2. Description of the Related Art Conventionally, for example, indium tin oxide (ITO) formed on a liquid crystal display panel using a plastic substrate has been used.
n oxide: indium tin oxide) and L
As a method for electrically connecting an external circuit such as an integrated circuit board such as a flexible board on which SI (large scale integration) or the like is mounted, pressure bonding using an anisotropic conductive film is performed.

[0003] The anisotropic conductive film is a film in which conductive particles are dispersed in an insulating material (binder) having adhesive properties. For example, the conductive particles are contained in an insulating epoxy-based thermosetting adhesive. Dispersions are known.

[0004] As the above-mentioned conductive particles, for example, those in which a substrate made of a cross-linked polystyrene is used as a core and its surface is plated with nickel-gold are known. For example, Japanese Patent Application Laid-Open No. 9-199206 discloses that a resin particle surface is plated with gold / nickel to a thickness of 0.03 μm / 0.1 μm and has a compressive strength at a 10% compression displacement of 68.
An anisotropic conductive film using conductive particles of 6 MPa or less and a recovery rate at the time of compressive displacement of 10% or more is described. Japanese Patent Application Laid-Open No. Hei 7-220439 discloses that gold / nickel is coated on a resin particle surface at 0.02 μm / 0.2 μm.
Anisotropic conductive films using conductive particles plated with a thickness of 3 mm are described.

[0005] In manufacturing a liquid crystal display device using the anisotropic conductive film, mounting of an external circuit on the liquid crystal display panel is performed by sandwiching the anisotropic conductive film on a plastic substrate of the liquid crystal display panel. Heating and pressurization are performed by aligning the positions of the connection terminals and the connection terminals on the flexible substrate as an external circuit. As a result, the conductive particles remove the binder and come into contact with both connection terminals, so that electrical connection between both connection terminals is performed.

[0006]

However, when a plastic substrate is used as the liquid crystal display panel, in the conventional method, an anisotropic conductive film is attached to the ITO connection terminal formed on the plastic substrate at the time of pressure bonding. The conductive particles contained therein tend to cause scratches such as cracks, causing problems such as disconnection and the like, and problems such as unstable display of liquid crystal.

The above-mentioned Japanese Patent Application Laid-Open Nos. Hei 7-220439 and Hei 9-199206 do not specifically disclose the problem of terminal connection when a plastic substrate is used.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide, in particular, an anisotropic connection to a connection terminal such as an ITO connection terminal formed on a liquid crystal display panel using a plastic substrate. In the crimping of an external circuit using a conductive conductive film, disconnection is reduced by reducing cracks in connection terminals due to conductive particles in the anisotropic conductive film during crimping, and stable liquid crystal display can be performed. It is an object of the present invention to provide a liquid crystal display device and a manufacturing method thereof. Another object of the present invention is to provide an anisotropic conductive film which is used for manufacturing the liquid crystal display device and can reduce cracks of connection terminals due to conductive particles in the anisotropic conductive film at the time of pressing. It is in.
A further object of the present invention is to provide a method of mounting an external circuit suitably used for manufacturing the liquid crystal display device.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to achieve the above-mentioned object. As a result, in the conventional mounting, the conductive particles were flattened after the binder was removed at the time of crimping, and the flattening was performed. It is found that if the connection terminal such as a terminal is seriously damaged, the connection terminal formed on the plastic substrate will be cracked if the damage to the connection terminal is large, causing a defect such as disconnection. When crimping an external circuit in the state of simply compressing and flattening without breaking the particles, we found that the display of the liquid crystal was unstable due to the problem of electrical connection, and had a thin metal layer on the surface of the base material, Through an anisotropic conductive film obtained by dispersing conductive particles having a metal thin-layer breaking stress of 73.0 MPa or less in an insulating material having an adhesive property, the conductive particles are connected to connection terminals of a liquid crystal panel using a plastic substrate. By applying a load equal to or more than the load for breaking the thin metal layer per conductive particle per one of the conductive particles and crimping the circuit under a load condition under which the thin metal layer of the conductive particles is broken, damage to the connection terminal is reduced. In addition to suppressing cracks and reducing breaks, electrical connection can be improved by breaking the thin metal layer on the surface of the conductive particles at the time of pressing, thereby stabilizing the display of the liquid crystal. The inventors have found that the present invention can be performed, and have completed the present invention.

That is, in order to solve the above-mentioned problems, the liquid crystal display device according to the present invention has a connection terminal (for example, an ITO connection terminal) of a liquid crystal panel using a plastic substrate and an external circuit (for example, a flexible substrate. (For crimping, the connection terminals are used) and an insulating material (for example, an insulating binder) having an adhesive property with conductive particles having a thin metal layer (for example, a plating layer) on the surface of the substrate.
Through the anisotropic conductive film in which the conductive particles have a metal thin layer breaking stress (for example, plating breaking stress) of 73.0 MPa or less. It is characterized in that it is crimped by applying a load greater than a load (for example, a plating breaking load).

In the present invention, the metal thin layer breaking load of the conductive particles is a load at which the thin metal layer of the conductive particles is broken when a load is applied to the conductive particles and compressed. The thin metal layer breaking stress of the conductive particles is the particle size d
The value obtained by dividing the metal thin layer breaking load of one conductive particle by π (d / 2) ² .

According to the above-described structure, when the external circuit is crimped to the connection terminal of the liquid crystal panel using the plastic substrate, the conductive particles having a thin metal layer on the surface of the base material are used. By breaking the thin metal layer by applying a load equal to or more than the load for breaking the thin metal layer per unit, it is possible to improve the electrical connection and to stabilize the display of the liquid crystal.

According to the above configuration, the metal thin layer breaking stress of the conductive particles is set to 73.0 MPa or less.
At the time of crimping, damage to the connection terminal can break the thin metal layer in the conductive particles with a small load, and particularly damage to the connection terminal such as an ITO connection terminal formed on a plastic substrate can be reduced. Therefore, cracks in the connection terminals due to the conductive particles can be reduced, and disconnection or the like due to cracks in the connection terminals can be reduced.

Therefore, according to the above configuration, in the crimping of the external circuit using the anisotropic conductive film to the connection terminal formed on the liquid crystal display panel using the plastic substrate, It is possible to provide a liquid crystal display device capable of reducing cracks in connection terminals due to conductive particles in a conductive film, reducing the incidence of disconnection failure caused by the cracks, and performing stable liquid crystal display. .

In order to solve the above-mentioned problems, a method of manufacturing a liquid crystal display device according to the present invention comprises the steps of: bonding conductive particles having a thin metal layer (eg, a plating layer) on a substrate surface to an insulating material having an adhesive property; (E.g., an IT-based connection terminal of a liquid crystal panel using a plastic substrate via an anisotropic conductive film dispersed in an insulating binder).
A method for manufacturing a liquid crystal display device in which an O connection terminal) and an external circuit (for example, a flexible substrate, and the connection terminal is used for connection (crimping)) are used, wherein the metal thin layer of the conductive particles is broken. Stress (for example, plating breaking stress) is 7
The compression bonding is performed by applying a load equal to or less than 3.0 MPa and equal to or more than a metal thin layer breaking load (for example, a plating breaking load) to each conductive particle.

According to the above method, when the external circuit is pressed against the connection terminal of the liquid crystal panel using the plastic substrate, the conductive particles having a thin metal layer on the surface of the base material are used. By breaking the thin metal layer by applying a load equal to or more than the load for breaking the thin metal layer per unit, it is possible to improve the electrical connection and to stabilize the display of the liquid crystal.

According to the above method, by setting the metal thin layer breaking stress of the conductive particles to 73.0 MPa or less,
At the time of crimping, damage to the connection terminal can break the thin metal layer in the conductive particles with a small load, and particularly damage to the connection terminal such as an ITO connection terminal formed on a plastic substrate can be reduced. Therefore, cracks in the connection terminals due to the conductive particles can be reduced, and disconnection or the like due to cracks in the connection terminals can be reduced.

Therefore, according to the above method, in the press-fitting of an external circuit using an anisotropic conductive film to a connection terminal formed on a liquid crystal display panel using a plastic substrate, It is possible to obtain a liquid crystal display device in which cracks in the connection terminals due to conductive particles in the conductive film are reduced, the rate of occurrence of disconnection failure due to the cracks is reduced, and stable liquid crystal display can be performed.

Further, in order to solve the above-mentioned problems, the anisotropic conductive film according to the present invention is characterized in that conductive particles having a thin metal layer (for example, a plating layer) on the surface of a substrate are coated with an insulating material ( An anisotropic conductive film dispersed in an insulating binder, for example, wherein the conductive particles have a thin metal layer breaking stress (for example, plating breaking stress) of 7;
It is characterized by being 3.0 MPa or less.

According to the above structure, when the conductive particles have a metal thin layer breaking stress of 73.0 MPa or less, when used in the production of the liquid crystal display device, the damage to the connection terminals during crimping is small. The thin metal layer in the conductive particles can be broken by, and damage to connection terminals such as ITO connection terminals formed on a plastic substrate can be reduced, and cracks in the connection terminals due to the conductive particles can be reduced. It is possible to reduce disconnection and the like due to cracks in the connection terminals.

The anisotropic conductive film according to the present invention, in order to solve the above-mentioned problems, has a structure in which the conductive particles are subjected to nickel-gold plating on the surface of a base material, and the nickel layer has a thickness of 0.1 mm. It is characterized by being less than 17 μm.

When the conductive particles are formed by plating the surface of a base material with nickel-gold, gold is ductile and soft, so that there is little damage to connection terminals such as ITO connection terminals. By reducing the thickness of the nickel layer, the thin metal layer breaking stress can be reduced, the damage to the connection terminal can be reduced, and the occurrence of cracks in the connection terminal can be reduced.

Further, in order to solve the above-mentioned problems, the method for mounting an external circuit according to the present invention comprises the steps of: bonding conductive particles having a thin metal layer (for example, a plating layer) on the surface of a substrate to an insulating material having an adhesive property (for example, An external circuit (for example, a flexible substrate) is connected to a connection terminal (for example, an ITO connection terminal) on a plastic substrate (for example, a plastic substrate used for a liquid crystal panel) via an anisotropic conductive film dispersed in an insulating binder. And the connection (crimping)
In the external circuit mounting method of crimping the connection terminal, the above-mentioned anisotropic conductive film is subjected to a load equal to or more than a metal layer breaking load (for example, plating breaking load) per conductive particle. It is characterized by performing pressure bonding.

According to the above method, when the external circuit is crimped to the connection terminal on the plastic substrate, conductive particles having a thin metal layer on the surface of the base material are used. By breaking the metal thin layer by applying a load equal to or greater than the metal thin layer breaking load, the electrical connection between the connection terminal on the plastic substrate and the external circuit (connection terminal of the external circuit) can be improved. Therefore, in the manufacture of the liquid crystal display device, by using the above-described method for crimping (mounting) the external circuit to the connection terminal of the liquid crystal panel using the plastic substrate, the connection terminal of the liquid crystal panel using the plastic substrate can be used. The electrical connection with an external circuit (connection terminal of the external circuit) can be improved, and the display of the liquid crystal can be stabilized.

[0025]

[Embodiment 1] An embodiment according to the present invention will be described below with reference to FIGS. 1 (a) and (b) to FIG. FIG. 3 shows a schematic configuration of the anisotropic conductive film used in the present embodiment. FIG. 4 is a sectional view showing a schematic configuration of the conductive particles dispersed in the anisotropic conductive film shown in FIG.

As shown in FIG. 3, the anisotropic conductive film 21 used in the present embodiment is obtained by dispersing conductive particles 11 in an adhesive resin 12 (binder) as an insulating material having adhesiveness. Has the following configuration. As the adhesive resin 12, for example, an epoxy-based thermosetting adhesive is preferably used.

The conductive particles 11 are, as shown in FIG.
For example, a nickel-gold plating is applied to the surface of the base material 1 serving as a core, so that a nickel layer 2 is formed as a thin metal layer.
a (Ni plating layer) and a gold layer 2b (Au plating layer).

As the substrate 1 serving as the core, for example,
Acrylic resins, polystyrene resins such as cross-linked polystyrene, styrene-acrylic copolymer resins, urethane resins, epoxy resins, and polyester resins are preferably used.

The mixing ratio of the conductive particles 11 to the adhesive resin 12 is determined by the connection pitch between the connection terminals on the plastic substrate used for mounting and the connection terminals of the external circuit, that is, the distance between the connection terminals and the connection terminals. May be appropriately set according to the area of the device, etc., and is not particularly limited.

The average thickness of the anisotropic conductive film 21, the average particle size of the conductive particles 11, the thickness of the plating layer 2 (thin metal layer) are not particularly limited. When mounting an external circuit such as a flexible board on which an LSI or the like is mounted using a liquid crystal panel, the conductive particles 11 are conductive particles having an average particle diameter of 10 μm ± 2 μm, usually 10 μm. 1
1 is used.

The anisotropic conductive film 21 used in the present embodiment includes the anisotropic conductive film 2
This is an anisotropic conductive film in which the metal thin-layer breaking stress of the conductive particles 11 dispersed in 1, that is, the plating breaking stress is 73.0 MPa or less. In the present embodiment,
The plating fracture stress (metal thin layer fracture stress) of the conductive particles 11 is a value obtained by dividing the plating fracture load (metal thin layer fracture load) of the conductive particles 11 having a particle diameter d by π (d / 2) ^2. .
The plating breaking load of the conductive particles 11 (metal thin layer breaking load) refers to the plating layer 2 (metal thin layer) of the conductive particles 11 when a load is applied to the conductive particles 11 and compressed.
Shows the load at which is destroyed. By setting the plating breaking stress (metal thin layer breaking stress) of the conductive particles 11 to 73.0 MPa or less, particularly, a connection terminal such as an ITO connection terminal on a liquid crystal panel (plastic liquid crystal panel) using a plastic substrate, In an anisotropic conductive film for connecting to a connection terminal of an external circuit, the hardness (metal thin layer breaking stress) of the conductive particles 11 is reduced as long as connection reliability can be ensured, and the connection terminal formed on a plastic substrate The occurrence of cracks on the surface can be reduced.

The method of measuring the plating breaking load (metal thin layer breaking load) of the conductive particles 11 will be described below with reference to FIG.
This will be described with reference to FIG.

As shown in FIG. 5, the measurement of the plating breaking load (metal thin layer breaking load) of the conductive particles 11 is performed by sandwiching one conductive particle 11 having a particle diameter d with a metal tool 41 and compressing the conductive load. Is performed by examining the relationship between the load at this time and the compression displacement of the conductive particles 11.

The measurement conditions were as follows: room temperature, 0.4462 mN /
The load is increased at the rate of s and compression is performed. For the above measurement, a Shimadzu micro compression tester (model name: M
CTM-500PC) was used.

FIG. 6 shows the relationship between the load (compression load) and the compression displacement of the conductive particles 11 measured by the above method. As shown in FIG. 6, when the conductive particles 11 are compressed, the compression load increases with the compression.
It will be constant. The load at this time is a plating breaking load (metal thin layer breaking load), and indicates a load when the plating layer 12 (metal thin layer) of the conductive particles 11 is broken.

The plating breaking load (metal thin layer breaking load) is
The particle diameter of the conductive particles 11, more specifically, the particle diameter of the resin (that is, the base material 1) serving as the core, the layer thickness of the plating layer 2 (thin metal layer), and the plating layer 2 (thin metal layer) The compression displacement and the compression ratio of the conductive particles when the plating layer 2 (thin metal layer) is destroyed also differ according to the various conditions described above. -When the conductive particles 11 having a particle size of 10 μm subjected to gold plating are used, when the conductive particles 11 are compressed by about 20%, more specifically, when the conductive particles 11 are compressed to 1.3 μm to 2.6 μm, Destruction occurs.

The plating breaking load (metal thin layer breaking load) measured as described above was changed to the cross-sectional area (π
(D / 2) ² ; The value obtained by dividing by d is the particle size of the conductive particles 11 is the plating breaking stress (metal thin layer breaking stress), which is easy to flatten (break), and furthermore, the pressure required for breaking. (Load) is an index. That is, by measuring the plating breaking load (metal thin layer breaking load) and the plating breaking stress (metal thin layer breaking stress), it is possible to measure the ease of flattening (breaking) of the conductive particles 11. The smaller the plating breaking load (metal thin layer breaking load) and plating breaking stress (metal thin layer breaking stress), the easier it is to flatten, the easier it is to break under low pressure (load), and on the plastic substrate such as ITO connection terminals during crimping. Damage to the connection terminals formed on the substrate is small.

As means for reducing the plating breaking load and the plating breaking stress of the conductive particles 11, for example, the conductive particles 11 may be provided with a plating layer 2 of nickel-gold plating as shown in FIG. And a method of reducing the plating thickness of the nickel layer 2a.

The conductive particles 11 shown in FIG. 4 are obtained by plating the substrate 1 with nickel and then gold. Of these metals, gold is ductile and soft, so ITO
There is little damage to connection terminals such as connection terminals. However, since nickel is hard, reducing the thickness of the nickel layer 2a has the effect of reducing damage to the connection terminals. In fact, the thinner the nickel plating thickness, the smaller the plating breaking load (metal thin layer breaking load) and thus the plating breaking stress (metal thin layer breaking stress). Therefore, as the nickel plating thickness is reduced, damage to connection terminals such as ITO connection terminals is reduced, and the occurrence of cracks in the connection terminals can be reduced.

I of a liquid crystal panel made of a plastic substrate
When mounting an external circuit such as a flexible board on which an LSI or the like is mounted on a connection terminal such as a TO connection terminal, the surface of the base material 1 is plated with nickel-gold as the conductive particles 11 as shown in FIG. When the conductive particles 11 are used, the thickness of the nickel layer 2a is less than 0.17 μm (that is, more than 0 and less than 0.17 μm), which reduces damage to connection terminals such as ITO connection terminals. However, it is preferable in terms of suppressing the occurrence of cracks in the connection terminal, and more preferably 0.167 μm or less. As the conductive particles 11, for example, an average particle size of 1
When the conductive particles 11 having a thickness of 0 μm are used, the thickness of the nickel layer 2a is more preferably in the range of 0.15 μm or more and less than 0.17 μm. The nickel layer 2a
By setting the layer thickness to 0.15 μm or more, failure occurs in, for example, a high-temperature and high-humidity test (60 ° C., 95% RH) and a heat shock test (−30 ° C./80° C., 1 hour each). And stable results can be obtained.

Further, the plating fracture stress (metal thin layer fracture stress) of the conductive particles 11 is 73.0 MPa or less (however, 0
However, it is possible to reduce the occurrence of cracks in the connection terminals formed on the plastic substrate.
When the conductive particles 11 of m are used, the plating breaking stress (metal thin layer breaking stress) of the conductive particles 11 is 53.0 MP.
a or more, for example, a high temperature and high humidity test (60 ° C.,
95% RH), heat shock test (−30 ° C./80)
° C, 1 hour each)
A stable result can be obtained. Therefore, in this case, the plating fracture stress (metal thin layer fracture stress) of the conductive particles 11 is more preferably 53.0 MPa or more and 73.0 MPa or less.

Next, referring to FIGS. 1A and 1B and FIG. 2, a connection terminal formed on a liquid crystal display panel using a plastic substrate by using the anisotropic conductive film, A method of electrically connecting (mounting) connection terminals formed on a flexible substrate on which an LSI or the like is mounted as an external circuit will be described below.

FIG. 1A is a cross-sectional view schematically showing a configuration of a connection portion between a liquid crystal display panel and an external circuit in a liquid crystal display device according to the present embodiment, and FIG. FIG. 1A is a sectional view taken along line AA ′ of FIG. FIG. 2 is an explanatory view showing a method of mounting the external circuit using an anisotropic conductive film on the liquid crystal display panel shown in FIGS. 1 (a) and 1 (b).

First, as shown in FIG. 2, an ITO connection terminal 32 (connection terminal) formed on a plastic substrate 31 used for a liquid crystal display panel with an anisotropic conductive film 21 interposed therebetween, The copper connection terminals 34 formed on the flexible substrate 33 are aligned.

Next, the connecting portion between the plastic substrate 31 and the flexible substrate 33, that is, the bonding portion between the connecting terminals of the two substrates, which are disposed to face each other with the anisotropic conductive film 21 interposed therebetween, is added in the compression direction. By heating while pressing, both substrates are pressed. At this time, the crimping is
For each conductive particle (conductive particles 11), a load equal to or greater than the metal thin layer breaking load of the conductive particles 11 dispersed in the anisotropic conductive film 21 is preferable. This is performed by applying a pressure (load) as small as possible under the condition that the plating layer 2 of the conductive particles 11 is broken, which is equal to or larger than the breaking load. That is, at the time of the pressure bonding, it is desirable to break the plating layer 2 of the conductive particles 11 under a pressure (load) as small as possible.
This is performed by applying a metal thin layer breaking load of the conductive particles 11 per conductive particle (conductive particles 11).

When the connection between the plastic substrate 31 and the flexible substrate 33 is heated while being pressed in the compression direction, the conductive particles 11 in the anisotropic conductive film 21 are bonded as shown in FIG. The agent resin 12 is removed, and the two contact terminals (the upper and lower connection terminals in FIG. 1A and FIG. 2) arranged opposite to each other with the anisotropic conductive film 21 interposed therebetween are brought into contact. By curing the adhesive resin 12 in this state, the electrical connection between the two connection terminals can be maintained, and the plastic substrate 31 and the flexible substrate 33 can be bonded.

FIG. 1A shows the plastic substrate 31.
The structure of the connection portion after the above and the flexible substrate 33 are crimped as described above is shown. FIG. 1 (b)
The connection portion after the plastic substrate 31 and the flexible substrate 33 are pressure-bonded as described above is denoted by A in FIG.
-Conductive particles 11 of a main part when viewed in a cross section taken along line -A '
The state of is shown. In the present embodiment, as shown in FIG. 1A, the conductive particles 11 in the anisotropic conductive film 21 are pressed at the bonding portion, thereby excluding the adhesive resin 12 and the ITO. The flattening occurs in a state of contacting the connection terminal 32 and the copper connection terminal 34, respectively. However, during the above-described crimping, the conductive particles 11 are subjected to a load equal to or greater than the metal layer destruction load of the conductive particles 11 so that FIG. As shown in b), the ITO connection terminal 32 and the copper connection terminal 34
, And the plating layer 2 of the conductive particles 11 contacting these connection terminals is broken. In FIG. 1B, the conductive particles 11 sandwiched between the ITO connection terminal 32 and the copper connection terminal 34 and in contact with these connection terminals (that is, FIG.
(B) Inside, conductive particles 1 in contact with copper connection terminal 34
In 1), when a load equal to or greater than the metal thin layer breaking load of the conductive particles 11 is applied, the conductive particles 11 are compressed and flattened, the nucleus is cracked and opened, and the plating layer 2 is cracked.

As described above, the flexible substrate 33 is connected to the ITO connection terminals 32 formed on the plastic substrate 31.
In the pressure bonding, conductive particles 11 having a plating layer 2 on the surface of the substrate 1 are used.
The electrical connection can be improved by breaking the plating layer 2 by applying a load equal to or greater than the metal thin layer breaking load per piece. As a result, the display of the liquid crystal can be stabilized.

Further, in the conventional mounting, at the time of crimping,
After the conductive particles have removed the binder, they flatten out and sink into the connection terminals such as the ITO connection terminals, thereby increasing the damage to the connection terminals and causing cracks in the connection terminals formed on the plastic substrate, resulting in disconnection. In some cases.

However, in the present embodiment, the conductive particles 11 are easily flattened by setting the thin metal layer breaking stress of the conductive particles 11 to 73.0 MPa or less.
Damage to the connection terminals such as the ITO connection terminals 32 can destroy the plating layer 2 of the conductive particles 11 with a small load. As a result, damage to the connection terminals such as the ITO connection terminals 32 can be reduced, and cracks in the connection terminals such as the ITO connection terminals 32 due to the conductive particles 11 can be reduced. It is possible to reduce the disconnection or the like caused by the disconnection.

As described above, the liquid crystal display device according to the present embodiment has a connection terminal and an external circuit of a liquid crystal panel using a plastic substrate and a thin metal layer such as a plating layer on the surface of the base material. The conductive particles are dispersed in an insulating material (binder) having adhesiveness, and the conductive particles have a thin metal layer breaking stress of 73.0 MPa or less. It has a configuration in which a load equal to or greater than the metal thin layer breaking load is applied and pressed.

In the liquid crystal display device, for example, connection terminals of a liquid crystal panel using a plastic substrate and connection terminals on a flexible substrate are connected via the anisotropic conductive film described above.

The above-mentioned liquid crystal display device has a structure in which one conductive particle is sandwiched between a connection terminal of a liquid crystal panel using the plastic substrate and a connection terminal of an external circuit such as a flexible substrate. In this case, the metal thin layer is broken by being pressed with a load equal to or more than the metal thin layer breaking load.

Further, in order to obtain the above-mentioned liquid crystal display device, the method for manufacturing a liquid crystal display device according to the present embodiment is characterized in that the conductive particles having a thin metal layer such as a plating layer are
When a connection terminal of a liquid crystal panel using a plastic substrate is crimped to an external circuit via an anisotropic conductive film dispersed in an insulating material (binder) having an adhesive property, a metal thin layer breaking stress is reduced. The above pressure bonding is performed using conductive particles of 73.0 MPa or less and applying a load equal to or greater than the metal thin layer breaking load per conductive particle.

As described above, according to the present embodiment, the metal thin layer breaking stress of the conductive particles is set to 73.0 MPa or less, so that the conductive particles are subjected to a small load during crimping with a small load. The thin metal layer can be destroyed, and damage to connection terminals such as ITO connection terminals formed on a plastic substrate can be reduced,
Cracks in the connection terminal due to the conductive particles can be reduced, and disconnection or the like due to cracks in the connection terminal can be reduced.

When the external circuit is crimped to the connection terminals of the liquid crystal panel using the plastic substrate, conductive particles having a thin metal layer on the surface of the base material are used. By breaking the thin metal layer by applying a load equal to or greater than the layer breaking load, the electrical connection can be improved and the display of the liquid crystal can be stabilized.

As described above, the anisotropic conductive film used in the present embodiment is obtained by bonding conductive particles having a thin metal layer such as a plating layer on the surface of a base material to an insulating material having an adhesive property. (A binder), and the conductive particles have a metal thin layer breaking stress (for example, plating breaking stress) of 73.0 MPa or less.

For this reason, when the anisotropic conductive film is used for manufacturing the liquid crystal display device, the thin metal layer of the conductive particles can be destroyed by a small load at the time of pressure bonding so that damage to the connection terminal is small. In particular, damage to connection terminals such as ITO connection terminals formed on a plastic substrate can be reduced, cracks in the connection terminals due to the conductive particles can be reduced, and disconnection due to cracks in the connection terminals can be reduced. Etc. can be reduced.

Further, as described above, the method of mounting an external circuit according to the present embodiment uses the conductive particles having a thin metal layer such as a plating layer on the surface of a base material to form an insulating material (binder) having an adhesive property. When an external circuit is crimped to a connection terminal on a plastic substrate (for example, a plastic substrate used for a liquid crystal panel) via an anisotropic conductive film dispersed therein, the conductive film is applied to the anisotropic conductive film. This is a method in which the above-mentioned pressure bonding is performed by applying a load equal to or more than the metal thin layer breaking load per particle.

According to the above method, when the external circuit is crimped to the connection terminal on the plastic substrate, the conductive particles having a thin metal layer on the base material surface are used.
The electrical connection between the connection terminal on the plastic substrate and the external circuit (connection terminal of the external circuit) is improved by breaking the metal thin layer by applying a load equal to or more than the metal thin layer breaking load per piece. be able to. Therefore, in the manufacture of the liquid crystal display device, by using the above-described method for crimping (mounting) the external circuit to the connection terminal of the liquid crystal panel using the plastic substrate, the connection terminal of the liquid crystal panel using the plastic substrate can be used. The electrical connection with an external circuit (connection terminal of the external circuit) can be improved, and the display of the liquid crystal can be stabilized.

In the above description, the conductive particles 11
Has been described as an example in which the plating layer 2 includes a nickel layer 2a and a gold layer 2b formed by nickel-gold plating, but the plating layer 2 formed on the surface of the base material 1 of the conductive particles 11 is described. The (metal thin layer) is not limited to this, and it goes without saying that a combination other than nickel / gold may be used. As a method for forming a thin metal layer formed on the surface of the base material 1 of the conductive particles 11, an electroless plating method is suitably used. There is no particular limitation as long as the plating can be performed. For example, various plating methods can be used.

[0062]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples, but the present invention is not limited thereto.

[Examples 1 to 3 and Comparative Examples 1 and 2] First, a crosslinked polystyrene was used as a base material, and the surface of the base material was subjected to nickel-gold plating by varying the thickness of a Ni plating layer. In addition, conductive particles having a particle diameter of 10 μm with different thicknesses of the Ni plating layer (hereinafter referred to as Ni plating thickness) were prepared. The average thickness of the Au plating layer was 0.05 μm. The plating breaking load (metal thin layer breaking load) and the plating breaking stress (metal thin layer breaking stress) of the conductive particles when the Ni plating thickness of the conductive particles was changed were measured based on FIGS. 5 and 6. .

By dispersing the conductive particles thus obtained in a predetermined ratio in an epoxy-based thermosetting adhesive, anisotropic conductive films using conductive particles having different Ni plating thicknesses were prepared. did. The average thickness of the anisotropic conductive film was 17 μm.

Next, using the respective anisotropic conductive films, a load equal to or greater than the plating breaking load is applied to each of the conductive particles, and the ITO connection terminals of the liquid crystal panel using a plastic substrate and the flexible substrate are used. Cracks (ITO cracks) on the ITO connection terminals when a plastic liquid crystal module was produced by crimping the copper connection terminals were evaluated. Compression bonding using each anisotropic conductive film was performed under the same conditions in each case.
The cracks were confirmed by preparing the plastic liquid crystal module and then peeling off the flexible substrate, and observing cracks generated on the ITO connection substrate with a microscope. The occurrence of cracks was checked for 100 ITO connection terminals, and "」 "indicates that no crack was observed," △ "indicates that cracks were observed but less than 20," 20 ", and 20 cracks What was confirmed above was rated as "x". Table 1 shows the results together with the plating breaking load and plating breaking stress of the conductive particles when the Ni plating thickness of the conductive particles was changed.
Shown in In Table 1, as the Ni plating thickness,
Numerical values when 0.20 μm is set to 100 are also shown.

[0066]

[Table 1]

As can be seen from Table 1, it was confirmed that cracks occurred when the plating fracture stress of the conductive particles was higher than 73.0 MPa.

Example 4 The stability of the liquid crystal display of a liquid crystal module manufactured in the same manner as in Examples 1 to 3 was observed. As a result, in each case, the display of the liquid crystal was stable.

[Comparative Example 3] Except that a load less than the metal thin film breaking load was applied per conductive particle and the ITO connection terminal of a liquid crystal panel using a plastic substrate and the copper connection terminal of a flexible substrate were crimped. A plastic liquid crystal module was manufactured in the same manner as in Examples 1 to 3 and Comparative Examples 1 and 2, and the stability of the liquid crystal display was observed. Compression bonding using each anisotropic conductive film was performed under the same conditions in each case. As a result, it was confirmed that when the above pressure bonding was performed with the load per conductive particle being less than the plating breaking load, the liquid crystal display of the obtained liquid crystal module became unstable in any case.

[0070]

As described above, the liquid crystal display device according to the present invention has an adhesive property between a connection terminal of a liquid crystal panel using a plastic substrate and an external circuit and a conductive particle having a thin metal layer on the surface of a base material. Through an anisotropic conductive film in which the conductive particles are dispersed in an insulating material having a metal thin layer breaking stress of 73.0 MPa or less. This is a configuration in which a load is applied and crimped.

According to the above configuration, when the external circuit is pressed against the connection terminal of the liquid crystal panel using the plastic substrate, the conductive particles having a thin metal layer on the surface of the base material are used. By breaking the thin metal layer by applying a load equal to or more than the load for breaking the thin metal layer per unit, it is possible to improve the electrical connection and to stabilize the display of the liquid crystal.

Further, according to the above configuration, the thin metal layer of the conductive particles can be destroyed with a small load at the time of crimping so that the connection terminal is not damaged. Damage to the connection terminal can be reduced. For this reason, cracks in the connection terminals due to the conductive particles can be reduced, so that disconnection and the like caused by cracks in the connection terminals can be reduced.

Therefore, in the pressure bonding of an external circuit using an anisotropic conductive film to a connection terminal formed on a liquid crystal display panel using a plastic substrate, conductive particles in the anisotropic conductive film at the time of pressure bonding. This leads to an effect that a liquid crystal display device capable of reducing the occurrence of disconnection defects due to the cracks and providing a stable liquid crystal display can be provided.

As described above, the method of manufacturing a liquid crystal display device according to the present invention is an anisotropic conductive film obtained by dispersing conductive particles having a thin metal layer on the surface of a base material in an insulating material having an adhesive property. A method for manufacturing a liquid crystal display device in which a connection terminal of a liquid crystal panel and an external circuit using a plastic substrate are pressure-bonded through a plastic substrate, wherein the conductive particles have a metal thin layer breaking stress of 73.0 MPa or less, This is a method in which the above-mentioned pressure bonding is performed by applying a load equal to or more than the metal thin layer breaking load per particle.

According to the above method, when the external circuit is pressed against the connection terminal of the liquid crystal panel using the plastic substrate, the conductive particles having a thin metal layer on the surface of the base material are used. By breaking the thin metal layer by applying a load equal to or more than the load for breaking the thin metal layer per unit, it is possible to improve the electrical connection and to stabilize the display of the liquid crystal.

Further, according to the above method, the thin metal layer of the conductive particles can be destroyed with a small load at the time of crimping so that the connection terminal is not damaged. Damage to the connection terminal can be reduced. For this reason, cracks in the connection terminals due to the conductive particles can be reduced, so that disconnection and the like caused by cracks in the connection terminals can be reduced.

Therefore, in the pressure bonding of an external circuit using an anisotropic conductive film to a connection terminal formed on a liquid crystal display panel using a plastic substrate, conductive particles in the anisotropic conductive film at the time of pressure bonding. And the likelihood of providing a method of manufacturing a liquid crystal display device capable of reducing the incidence of disconnection failure caused by the cracks and displaying a stable liquid crystal. Play.

The anisotropic conductive film according to the present invention comprises, as described above, conductive particles having a thin metal layer on the surface of a substrate,
An anisotropic conductive film dispersed in an insulating material having adhesiveness, wherein the conductive particles have a metal thin layer breaking stress of 73.0 MPa or less.

Therefore, when used in the manufacture of the above-mentioned liquid crystal display device, the thin metal layer of the conductive particles can be broken by a small load at the time of crimping so that the connection terminal is not damaged. It is possible to reduce damage to the connection terminals such as the ITO connection terminals, which can reduce cracks in the connection terminals due to the conductive particles, and reduce disconnection and the like caused by cracks in the connection terminals. It has the effect of being able to.

As described above, the anisotropic conductive film according to the present invention is obtained by plating the above-mentioned conductive particles on the surface of the base material with nickel-gold, and the nickel layer has a thickness of 0.17 μm.
m.

When the conductive particles are formed by plating the surface of a base material with nickel-gold, nickel is hard. Therefore, by thinning this nickel layer, the thin metal layer breaking stress is reduced, and the damage to the connection terminals is reduced. Can be reduced. Therefore, according to the above configuration, it is possible to reduce the occurrence of cracks in the connection terminals.

As described above, the external circuit mounting method according to the present invention uses an anisotropic conductive film formed by dispersing conductive particles having a thin metal layer on the surface of a base material in an insulating material having adhesiveness. And an external circuit mounting method for pressing an external circuit to a connection terminal on a plastic substrate, wherein the anisotropic conductive film is subjected to a pressure equal to or greater than a metal thin layer breaking load per conductive particle. How to do it.

According to the above method, when the external circuit is crimped to the connection terminal on the plastic substrate, conductive particles having a thin metal layer on the surface of the base material are used. By breaking the metal thin layer by applying a load equal to or greater than the metal thin layer breaking load, the electrical connection between the connection terminal on the plastic substrate and the external circuit (connection terminal of the external circuit) can be improved. Therefore, when manufacturing the liquid crystal display device, by using the above-described method for crimping (mounting) the external circuit to the connection terminal of the liquid crystal panel using the plastic substrate, the connection terminal of the liquid crystal panel using the plastic substrate is used. And external circuit (connection terminal of external circuit)
This makes it possible to improve the electrical connection to the liquid crystal and stabilize the display of the liquid crystal.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view schematically showing a configuration of a connection portion between a liquid crystal display panel and an external circuit in a liquid crystal display device according to an embodiment of the present invention, and FIG. A
FIG. 4 is a sectional view taken along line -A ′.

FIG. 2 is an explanatory view showing a method of mounting an external circuit using an anisotropic conductive film on the liquid crystal display panel shown in FIG.

FIG. 3 is a cross-sectional view illustrating a schematic configuration of an anisotropic conductive film used in one embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a schematic configuration of conductive particles dispersed in the anisotropic conductive film shown in FIG.

5 is an explanatory view showing a method for measuring a plating breaking load of the conductive particles shown in FIG.

FIG. 6 is a graph showing the relationship between the load and the compression displacement of the conductive particles measured by the method shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base material 2 Plating layer (thin metal layer) 2a Nickel layer (thin metal layer) 2b Gold layer (thin metal layer) 11 Conductive particles 12 Adhesive resin (insulating material) 21 Anisotropic conductive film 31 Plastic substrate 32 ITO connection Terminal (connection terminal) 33 Flexible board (external circuit) 34 Copper connection terminal

Continued on front page F term (reference) 2H092 GA48 GA50 HA25 MA11 MA32 NA15 PA01 5E344 AA02 AA22 BB02 BB04 BB07 CD04 DD06 DD10 EE16 5G435 AA17 BB12 EE40 EE42 EE47 HH12 HH14 KK05

Claims (5)

[Claims] 1. A connection terminal and an external circuit of a liquid crystal panel using a plastic substrate, wherein conductive particles having a thin metal layer on the surface of a base material are dispersed in an insulating material having an adhesive property.
Through the anisotropic conductive film in which the thin metal layer breaking stress of the conductive particles is 73.0 MPa or less, it is required that the conductive particles be pressed and applied with a load equal to or more than the thin metal layer breaking load per conductive particle. Characteristic liquid crystal display device. 2. Conductive particles having a thin metal layer on the surface of a substrate,
A method for manufacturing a liquid crystal display device in which a connection terminal of a liquid crystal panel using a plastic substrate and an external circuit are pressure-bonded via an anisotropic conductive film dispersed in an insulating material having adhesiveness, A method for manufacturing a liquid crystal display device, wherein the metal layer has a metal thin layer breaking stress of 73.0 MPa or less, and the above-mentioned press-bonding is performed with a load equal to or greater than the metal thin layer breaking load per conductive particle. 3. Conductive particles having a thin metal layer on the surface of a substrate,
An anisotropic conductive film dispersed in an insulating material having an adhesive property, wherein the conductive particles have a metal thin-layer breaking stress of 73.0 MPa or less. 4. The method according to claim 1, wherein the conductive particles are formed by plating the surface of a substrate with nickel-gold, and the thickness of the nickel layer is 0.17 μm.
4. The anisotropic conductive film according to claim 3, wherein the thickness is less than m. 5. Conductive particles having a thin metal layer on the surface of a substrate,
An external circuit mounting method in which an external circuit is pressure-bonded to a connection terminal on a plastic substrate via an anisotropic conductive film dispersed in an insulating material having an adhesive property. Per piece,
An external circuit mounting method, wherein the crimping is performed by applying a load equal to or greater than the metal thin layer breaking load.