JPH10168411A - Anisotropically conductive adhesive, liquid crystal display and electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anisotropically conductive adhesive which itself has light-shielding function and therefore can dispense with any extra light-shielding member (e.g. light-shielding tape) and to provide a liquid crystal display and electronic equipment in each of which the structure for shielding a drive IC is very simple. SOLUTION: This invention provides an anisotropically conductive adhesive 13 which bonds an IC chip 2 to a transparent substrate 3a so that the bump of the chip 2 may be bonded to the respective electrode terminals 11 and 12 on the substrate 3a. This adhesive 13 comprises one which is opacified when cured or a previously colored one. The adhesive 13 may further contain a light absorber. The adhesive 13 inhibits light from reaching the IC 2. The adhesive 13 itself has light-shielding properties, and therefore can dispense with any extra light-shielding member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anisotropic conductive adhesive capable of achieving a connection having conductivity only in one direction. The invention also relates to a liquid crystal display using the anisotropic conductive adhesive. The invention also relates to an electronic device using the liquid crystal display device.

[0002]

2. Description of the Related Art It has been widely known that there is an anisotropic conductive adhesive as an adhesive for conductively connecting two objects. This anisotropic conductive adhesive has conductivity only in a single direction in a state where two objects are connected,
When a plurality of electrode terminals are formed on each of the two objects, it is used to electrically collectively connect individual electrode pairs.

On the other hand, a liquid crystal display device that modulates light by controlling the orientation of liquid crystal to thereby display visible information such as characters and numerals has been widely known. In such a liquid crystal display device, a liquid crystal display device in which a driver IC for driving a liquid crystal is directly bonded on a surface of a transparent substrate constituting a liquid crystal panel, that is, a so-called COG (Chip On Glass) type liquid crystal. Display devices are known. In such a COG type liquid crystal display device, there is known a so-called face-down type mounting method in which the driver IC is bonded to the transparent substrate with the active surface of the driver IC facing the transparent substrate. I have.

When the face-down method is adopted, an anisotropic conductive adhesive such as ACF (Anisotropic Co.) is provided between the active surface of the driver IC and the transparent substrate in many cases.
nductive Film: Anisotropic conductive film)
The ACF is cured while pressing the driver IC against the transparent substrate by heating and pressing. Then, by this processing, the driver IC is bonded on the transparent substrate. At this time,
Since the ACF is conductive only in one direction, the driver I
Each of the plurality of bumps provided on the active surface of C can be individually conductively connected to each of the plurality of electrode terminals formed on the transparent substrate.

In a COG type liquid crystal display device in which a driver IC is mounted in a face-down manner, light may be incident on an active surface of the driver IC through a transparent substrate. When light enters the active surface of the driver IC,
There is a possibility that the driver IC malfunctions and normal liquid crystal display cannot be performed. Usually, when light in a wavelength range of about 600 to 1100 nm is incident on the active surface of the driver IC, it is considered that the driver IC is likely to malfunction.
Conventionally, in order to prevent the inconvenience that light is incident on the active surface of the driver IC, a light-shielding tape is pasted on the back surface of the transparent substrate where the driver IC is bonded,
Measures were taken to block the incidence of light.

[0006]

However, sticking a light-shielding tape on a transparent substrate means that a processing step for that purpose is required, which complicates the manufacturing process of the liquid crystal display device. is there. In addition, the cost of parts is increased by the necessity of the light shielding tape. Further, since the light-shielding tape is attached not across the active surface of the driver IC but across the transparent substrate, it is separated from the active surface of the driver IC by the thickness of the transparent substrate. It was not enough to completely shade the surface.

The present invention has been made in view of the above problems, and is an anisotropic conductive adhesive capable of performing a light-shielding function by itself without using an extra light-shielding member such as a light-shielding tape. The first object is to provide It is a second object of the present invention to provide a liquid crystal display device capable of reliably blocking incident light to a driver IC without using an extra light blocking member such as a light blocking tape. It is a third object of the present invention to provide an electronic device which is less likely to malfunction with respect to a liquid crystal display portion.

[0008]

In order to achieve the first object, a first anisotropic conductive adhesive according to the present invention is arranged between a pair of objects and connects the objects to each other. ,
Conductive in a single direction across those objects,
And it has electrical insulation in directions other than the single direction. Further, the anisotropic conductive adhesive includes an adhesive that bonds the pair of objects to each other by curing,
The adhesive has the property of becoming opaque by curing.

Using this anisotropic conductive adhesive, a driver I
When bonding C to a transparent substrate, an anisotropic conductive adhesive is placed between the driver IC and the transparent substrate, and the driver IC
Is pressed against the transparent substrate, and the anisotropic conductive adhesive is cured by heating or the like. With this curing, the driver IC
And the transparent substrate are bonded to each other, and at the same time, the anisotropic conductive adhesive changes to opaque. Therefore, when the curing of the anisotropic conductive adhesive is completed and the driver IC is bonded on the transparent substrate, the anisotropic conductive adhesive becomes opaque, and thereafter, the active surface of the driver IC passes through the transparent substrate. Light is surely prevented from entering.

[0010] To achieve the first object, a second anisotropic conductive adhesive according to the present invention is arranged between a pair of objects to connect the objects to each other and to cross the objects. It has conductivity in a single direction and has electrical insulation in directions other than the single direction. Further, the anisotropic conductive adhesive includes an adhesive that cures the pair of objects to each other by curing, and the adhesive is formed of a colored resin. This anisotropic conductive adhesive is different from the above-described first anisotropic conductive adhesive in that the anisotropic conductive adhesive is not colored with curing but is colored in advance.

In order to achieve the first object, a third anisotropic conductive adhesive according to the present invention is disposed between a pair of objects, connects the objects to each other, and traverses the objects. It has conductivity in a single direction and has electrical insulation in directions other than the single direction. Further, the anisotropic conductive adhesive has an adhesive that cures the pair of objects to each other by curing, and a substance that is mixed in the adhesive and absorbs light. The anisotropic conductive adhesive does not develop color with curing, is not colored in advance, and has a light absorbing material mixed into the adhesive. And the second anisotropic conductive adhesive.

Regarding the third anisotropic conductive adhesive,
The following embodiments are possible. First, a resin solid is used as a light-absorbing substance. Second, a functional group having a light absorbing property is incorporated into the material constituting the adhesive. Third, carbon is used as a light-absorbing substance. Fourth, ceramic is used as a material for absorbing light.

Next, in order to achieve the second object, a liquid crystal display device according to the present invention comprises a pair of light-transmitting substrates facing each other across a liquid crystal, and at least one of the light-transmitting substrates. In a liquid crystal display device having an IC chip directly bonded to one of them, the IC chip is bonded to the translucent substrate by using any of the anisotropic conductive adhesives described above. It is characterized by the following.

Next, in order to achieve the third object, an electronic apparatus according to the present invention comprises the above-described liquid crystal display device, a power supply for supplying power to the liquid crystal display device, and the liquid crystal display device. And a CPU for controlling the above operation.

[0015]

FIG. 1 shows one embodiment of the anisotropic conductive adhesive according to the present invention and one embodiment of the liquid crystal display device according to the present invention. The liquid crystal display device shown here,
This is a COG (Chip On Glass) liquid crystal display device, which is manufactured by directly bonding a driver IC 2 to a liquid crystal panel 1.

As shown in FIG. 2, the liquid crystal panel 1 has a pair of transparent substrates facing each other, that is, translucent substrates 3a and 3b. These transparent substrates 3a and 3b are adhered to each other by a sealing material 6 with a predetermined gap therebetween by a bead-shaped spacer 4. This gap is generally called a cell gap.
Is enclosed.

Polarizing plates 9 and 9 are attached to the outer surfaces of the transparent substrates 3a and 3b, respectively. In addition, on the inner surfaces of the transparent substrates 3a and 3b, for example, IT
Transparent electrodes 8a and 8b having a predetermined pattern are formed by O (Indium Tin Oxide), and pixels for liquid crystal display are formed by these transparent electrodes.

An electrode terminal 1 for IC output, which is continuous with the transparent electrodes 8a and 8b, is provided on the surface of the protruding portion 3c of the one transparent substrate 3a which protrudes outside the other transparent substrate 3b.
1 and an IC input electrode terminal 12 are formed. ACF as an anisotropic conductive adhesive is provided on the substrate overhang portion 3c.
(Anisotropic Conductive Film) 13
Thereby, the driver IC 2 is bonded.

The ACF 13 includes an adhesive which is transparent in a normal state and has an opaque property when cured, and conductive particles dispersed in the adhesive. As shown in FIG. 1, an ACF 13 formed in a predetermined sheet shape is adhered to a predetermined position on the substrate overhang portion 3c, a driver IC 2 is aligned on the ACF 13, and then temporarily bonded. While heating the ACF 13, the driver IC 2 is pressed against the substrate overhang 3c with a predetermined pressing force.

By the above heating and pressurizing treatment, the driver IC 2 is adhered to the substrate overhang portion 3c, and the bumps 14 provided on the active surface 2a of the driver IC 2 are electrically conductive to the respective electrode terminals 11 and 12 through the conductive particles. Connecting. Since there is no conductive connection between the electrode terminals where no conductive particles are interposed, conductivity is achieved only in a single direction. Further, in the present embodiment, when the ACF 13 is heated and cured by the above-described pressurization and heat treatment for mounting the driver IC 2, the ACF 13 changes from a transparent state to an opaque state according to its own properties. Therefore, as shown in FIG. 2, the transparent substrate 3a of the driver IC 2
After the bonding to the ACF 13 is completed, the ACF 13 is in an opaque state. Since the ACF 13 before curing is transparent,
The workability when attaching the ACF 13 and the driver IC 2 to the substrate overhang 3c is not impaired.

In general, a liquid crystal display device is provided with a backlight, a reflector and the like for irradiating the liquid crystal 7 with light. The opaque ACF 13 has a specific wavelength range of light generated from a backlight or the like, for example, 400 to 1200 n.
Light in the range of m, preferably in the range of 600 to 1100 nm, is prevented from being incident on the active surface 2a of the driver IC 2. Thus, by preventing light from being incident on the active surface 2a of the driver IC 2, it is possible to reliably prevent the driver IC 2 from malfunctioning due to light.

The above liquid crystal display device is used for various electronic devices. For example, it can be used as a display unit of a mobile phone as shown in FIG. This mobile phone has an upper case 16 and a lower case 17. An antenna 18 for receiving and transmitting, a keyboard unit 19 and a microphone 21 are mounted on the upper case 16. Also, the lower case 17 includes
, A liquid crystal display device 22 including a liquid crystal panel 1 and a driver IC 2, a speaker 23, and a circuit board 24 are mounted.

As shown in FIG. 4, a control section 26 including a CPU, a transmitting section 27 connected to an output terminal of the microphone 12, and an input terminal of the speaker 23 are provided on the circuit board 24 as shown in FIG. And various circuit units such as a power supply unit 29 for supplying electric power to the respective units. The transmitting unit 27 includes the microphone 21
And modulates an audio signal corresponding to the audio collected by the controller and transmits the audio signal on a carrier wave. The receiving unit 28 demodulates the received audio signal and emits the sound from the speaker 23. The control unit 26 controls the output information of the keyboard 19 and the reception unit 28
Driver IC based on the received information received by
2, the display information is output to the driver IC 2, and the driver IC 2 drives the liquid crystal display device 22 based on the display information. This allows
A predetermined display is performed on the display surface of the liquid crystal display device 22.

Referring to FIG. 2, the liquid crystal display device 22 used in this portable telephone also has an opaque ACF 13 between the active surface 2a of the driver IC 2 and the transparent substrate 3a.
Is interposed, so that light is prevented from being incident on the active surface 2a, so that a stable display operation can always be obtained.

In the embodiment described above, the ACF 13
Was formed of a material having a property of becoming opaque when cured. However, A
The adhesive constituting the CF 13 may be formed of a pre-colored resin instead of such a material. Further, by mixing a light-absorbing substance into the adhesive, the ACF 13 can have a light-shielding property. Examples of such a light-absorbing substance include a solid resin, a resin having a functional group having a light-absorbing property, carbon, and ceramic.

Although the present invention has been described with reference to the preferred embodiment, the present invention is not limited to the embodiment, and can be variously modified within the technical scope described in the claims.

For example, the anisotropic conductive adhesive of the present invention is not limited to a film-like ACF (Anisotropic Conductive Film), but a paste-like ACA (Anisot Conductive Film).
ropicConductive Adhesive). Further, the liquid crystal display device to which the anisotropic conductive adhesive of the present invention can be applied is not limited to the liquid crystal display device having the structure shown in FIG. 1, and both transparent substrates have overhang portions, and both of the overhang portions are provided. A liquid crystal display device of a type in which a driver IC is mounted on the liquid crystal display device may be used. The number of driver ICs to be mounted is not limited to one, but may be plural.

Further, the liquid crystal display device of the present invention is not limited to a portable telephone, but can be applied to all other types of electronic devices requiring display. For example, the present invention can be applied to a display device of a personal computer, a display device of an electronic organizer, and various other electronic devices.

[0029]

According to the anisotropic conductive adhesive according to the first aspect, when the curing of the anisotropic conductive adhesive is completed and the pair of objects are bonded to each other, the anisotropic conductive adhesive is used. Since it is in an opaque state, a light-shielding function can be achieved only with an anisotropic conductive adhesive without requiring a special light-shielding member such as a light-shielding tape. Since a special light-blocking member is not required, a processing step for imparting light-blocking properties to an object requiring light-blocking can be simplified, and the cost of parts can be reduced. Furthermore, since the anisotropic conductive adhesive is in direct contact with the object to be joined due to its properties, the light-shielding property is remarkably improved as compared with the case where both are located apart from each other.

According to the anisotropic conductive adhesive according to the second aspect, since the anisotropic conductive adhesive colored in advance is used, the anisotropic conductive adhesive can be used without requiring any special light shielding member. The light-shielding function can be achieved only by the agent.

According to the anisotropic conductive adhesive of the third aspect, the light absorbing substance is mixed in the adhesive.
The light-shielding function can be achieved only with the anisotropic conductive adhesive without requiring a special light-shielding member.

According to the anisotropic conductive adhesive of the present invention, the light-absorbing substance can be surely mixed into the adhesive.

According to the liquid crystal display device of the eighth aspect,
Light incident on the active surface of the C chip can be reliably blocked by the anisotropic conductive adhesive. In particular, the anisotropic conductive adhesive has I
Since it is in direct contact with the active surface of the C chip, the light-shielding property is significantly improved as compared with the case where a light-shielding tape is attached to the opposite surface of the transparent substrate.

According to the electronic device of the ninth aspect, since the built-in liquid crystal display device does not malfunction due to light, a stable display operation can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of an anisotropic conductive adhesive according to the present invention and one embodiment of a liquid crystal display device according to the present invention.

FIG. 2 is a sectional view showing a sectional structure of the liquid crystal display device of FIG.

FIG. 3 is an exploded perspective view showing an embodiment of the electronic device according to the present invention.

4 is a circuit block diagram of the electronic device shown in FIG.

[Explanation of symbols]

 Reference Signs List 1 liquid crystal panel 2 driver IC (IC chip) 2a active surface 3a, 3b transparent substrate (translucent substrate) 3c substrate overhanging portion 4 spacer 6 sealing material 7 liquid crystal 8a, 8b transparent electrode 9 polarizing plate 11 IC output electrode terminal 12 Electrode terminal for IC input 13 ACF (anisotropic conductive adhesive) 14 Bump 16, 17 Case 19 Keyboard unit 21 Microphone 22 Liquid crystal display device 24 Circuit board

Claims (9)

[Claims] An object disposed between a pair of objects for connecting the objects to each other, having conductivity in a single direction across the objects, and electrically insulating in directions other than the single direction. An anisotropic conductive adhesive having an adhesive property, comprising an adhesive for bonding said pair of objects to each other by curing, said adhesive having a property of becoming opaque by curing. Agent. 2. An object disposed between a pair of objects for connecting the objects to each other, having conductivity in a single direction across the objects, and electrically insulating in directions other than the single direction. An anisotropic conductive adhesive having an adhesive property, comprising an adhesive that cures the pair of objects to each other by curing, and the adhesive is formed of a colored resin. adhesive. 3. An object disposed between a pair of objects, connecting the objects to each other, having conductivity in a single direction across the objects, and electrically insulating in directions other than the single direction. An anisotropic conductive adhesive having a property, comprising: an adhesive that cures the pair of objects to each other by curing; and a substance that is mixed in the adhesive and absorbs light. Anisotropic conductive adhesive. 4. The anisotropic conductive adhesive according to claim 3, wherein the light-absorbing substance is a resin solid. 5. The anisotropic conductive adhesive according to claim 3, wherein the light-absorbing substance is a functional group having a light-absorbing property incorporated in a material constituting the adhesive. Anisotropic conductive adhesive. 6. The anisotropic conductive adhesive according to claim 3, wherein the substance that absorbs light is carbon. 7. The anisotropic conductive adhesive according to claim 3, wherein the substance that absorbs light is ceramic. 8. A liquid crystal display device comprising: a pair of light-transmitting substrates facing each other across a liquid crystal; and an IC chip directly bonded to at least one of the light-transmitting substrates. A liquid crystal display device, wherein the IC chip is bonded to the translucent substrate using the anisotropic conductive adhesive according to any one of claims 1 to 7. 9. An electronic apparatus comprising: the liquid crystal display device according to claim 8; a power supply unit that supplies power to the liquid crystal display device; and a control unit that controls an operation of the liquid crystal display device.