Electronic device and method for manufacturing the same

Abstract

This invention provides an electronic device with excellent moisture resistance and adhesive strength, in which an FPC is connected to an electronic element substrate using ACF. [Solution] The electronic device 110A has an electronic element substrate 12 having electronic elements and wiring formed on a first substrate 12, a second substrate 14 disposed on the first substrate so as to expose terminal regions where terminals of the wiring are formed, a flexible circuit board 20A having circuits provided on a flexible film 22A, and an anisotropic conductive resin layer 32 disposed to electrically connect the circuits and terminals, and further has a moisture-proof resin portion formed to contact the first substrate, the second substrate and the film, the moisture-proof resin portion 42A is formed closer to the second substrate than the anisotropic conductive resin layer, and has a first portion 42a between the first substrate and the film, a second portion 42b between the second substrate and the film, and a third portion 42c on the surface opposite to the surface on which the anisotropic conductive resin layer of the film is formed, and the first portion, second portion and third portion are formed continuously.

Description

Technical Field

[0001] The present invention relates to an electronic device and a method for manufacturing the same, and more particularly, to an electronic device including an electronic element substrate and a flexible printed circuit (FPC) and a method for manufacturing the same.

Background Art

[0002] In an electronic device including an electronic element substrate and a flexible printed circuit, when connecting the flexible printed circuit to the electronic element substrate, an anisotropic conducting film (ACF) is used (for example, Patent Document 1).

[0003] For example, in a liquid crystal display device, a flexible printed circuit (FPC) on which a chip of a control circuit (IC) is mounted is connected to an active matrix substrate of a liquid crystal display panel using an ACF. The FPC on which the IC chip is mounted is called a chip-on-film (COF). Note that the COF may be treated as a form of the package of the IC chip. The FPC in this specification widely includes various forms of flexible printed circuits including tape automated bonding (TAB).

[0004] In a structure in which an FPC is connected to an electronic element substrate using an ACF, in addition to the electrical connection stability, moisture resistance (humidity resistance) and connection strength are also required.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Patent Document 1 discloses an ACF in which a moisture-proof layer is provided on part or all of the periphery of an anisotropic conductive resin layer. According to Patent Document 1, by using an ACF having a moisture-proof layer, moisture resistance and adhesive strength can be improved.

[0007] However, according to the inventors' research, sufficient adhesive strength may not be obtained even when using ACF having a moisture-proof layer as disclosed in Patent Document 1.

[0008] Therefore, the object of the present invention is to provide an electronic device and a method for manufacturing the same, which have excellent moisture resistance and adhesive strength in a structure in which an FPC is connected to an electronic element substrate using ACF. [Means for solving the problem]

[0009] According to embodiments of the present invention, the following solutions are provided.

[0010] [Item 1] An electronic element substrate comprising a first substrate, a plurality of electronic elements formed on the first substrate, and a plurality of wirings connected to the plurality of electronic elements, A second substrate is placed on the first substrate so as to expose the terminal region where the multiple terminals of the multiple wirings of the first substrate are formed, A flexible circuit board having a flexible film and a circuit provided on the film, An anisotropic conductive resin layer is disposed between the terminal region of the first substrate and the film to electrically connect the circuit and the plurality of terminals. It has, The first substrate, the second substrate, and the film further comprise a moisture-proof resin portion formed to be in contact with each other. The moisture-proof resin portion is formed closer to the second substrate than the anisotropic conductive resin layer, and the moisture-proof resin portion has a first portion between the first substrate and the film, a second portion between the second substrate and the film, and a third portion on the surface of the film opposite to the surface on which the anisotropic conductive resin layer is formed, and the first portion, the second portion and the third portion are formed continuously, in an electronic device. [Item 2] The film has through holes, The moisture-proof resin portion further has a fourth portion formed within the through hole, The electronic device according to item 1, wherein the fourth part is integrally formed with the first part and the third part. [Item 3] The electronic device according to item 2, wherein the through-hole has a shape that tapers toward the second substrate when viewed from the direction normal to the film. [Item 4] The film has a notch at the end face facing the second substrate. The second part includes a portion that enters the notch, as described in item 1. [Item 5] A method for manufacturing an electronic device as described in any of items 1 to 4, Step A is to prepare a flexible circuit board in which a moisture-proof resin material is applied to the region on the film where the first portion of the moisture-proof resin part is formed. Step B involves placing an anisotropic conductive resin material on the terminal region of the first substrate, Step C involves heat-pressing the flexible circuit board to the first substrate in a state in which the circuit of the flexible circuit board and the plurality of terminals on the first substrate are arranged to be electrically connected via the anisotropic conductive resin material. It includes, A manufacturing method comprising the steps C above, in which the anisotropic conductive material is cured to form the anisotropic conductive resin layer, and the moisture-proof resin material is melted, flowed, and cured to form the moisture-proof resin portion. [Effects of the Invention]

[0011] According to an embodiment of the present invention, there are provided an electronic device having excellent moisture resistance and adhesive strength in a structure in which an FPC is connected to an electronic element substrate using an ACF, and a method for manufacturing the same.

Brief Description of Drawings

[0012] [Figure 1] FIG. 10 is a schematic cross-sectional view of a liquid crystal display device 100A according to an embodiment of the present invention, corresponding to a cross-section along line I-I' in FIG. 2. [Figure 2] FIG. 13 is a schematic plan view of the liquid crystal display device 100A. [Figure 3] FIG. 16 is a schematic cross-sectional view showing a state in which a moisture-proof resin material 42R is applied to a flexible circuit board 20A used in the manufacture of the liquid crystal display device 100A, corresponding to a cross-section along line III-III' in FIG. 4. [Figure 4] FIG. 19 is a schematic plan view showing a state in which a moisture-proof resin material 42R is applied to the flexible circuit board 20A. [Figure 5] FIG. 22 is a schematic cross-sectional view of a liquid crystal display device 100B according to an embodiment of the present invention, corresponding to a cross-section along line V-V' in FIG. 6. [Figure 6] FIG. 25 is a schematic plan view of the liquid crystal display device 100B. [Figure 7] FIG. 28 is a schematic plan view showing a state in which a moisture-proof resin material 42R is applied to a flexible circuit board 20B used in the manufacture of the liquid crystal display device 100B. [Figure 8] FIG. 31 is a schematic plan view showing a state in which a moisture-proof resin material 42R is applied to a flexible circuit board 20C used in the manufacture of another liquid crystal display device according to an embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0013] Hereinafter, an electronic device according to an embodiment of the present invention and its manufacturing method will be described with reference to the drawings. An active-matrix liquid crystal display device will be used as an example of the electronic device, but the electronic device according to the embodiment of the present invention is not limited to a liquid crystal display device, but can be any kind of electronic device, including other display devices such as organic EL displays.

[0014] Figure 1 shows a schematic cross-sectional view of a liquid crystal display device 100A according to an embodiment of the present invention, and Figure 2 shows a schematic plan view of the liquid crystal display device 100A. Figure 1 corresponds to a cross-section along the line I-I' in Figure 2, but the liquid crystal display panel 10 in Figure 1 is omitted in Figure 2.

[0015] The liquid crystal display device 100A comprises a liquid crystal display panel 10 and an FPC 20A on which a control circuit (IC) is mounted using COF. The FPC 20A is connected to the liquid crystal display panel 10 using an AFC 32.

[0016] The liquid crystal display panel 10 includes an active matrix substrate (indicated by the same reference numeral as the glass substrate 12) 12 on which thin-film transistors (TFTs), pixel electrodes, and wiring are formed on a glass substrate 12; a counter substrate (indicated by the same reference numeral as the glass substrate 14) 14 having common electrodes and a color filter layer (not shown) on a glass substrate 14; and a liquid crystal layer (not shown) provided between these. The counter substrate 14 is positioned to expose terminal regions on the active matrix substrate 12 where multiple terminals 13 of multiple wirings are formed.

[0017] The FPC20A has a flexible film (e.g., a polyimide film) 22A and a circuit formed on the film 22A. The circuit includes, for example, a driver IC 24 and wiring 23. The driver IC 24 is connected to the wiring 23 by gold bumps 25 and fixed to the film 22A by sealing resin 26. The wiring 23 is covered with, for example, solder resist 28 so that the portion that is electrically connected to the terminals 13 of the active matrix substrate 12 is exposed.

[0018] The liquid crystal display device 100A has an anisotropic conductive resin layer 32 positioned between the terminal region of the glass substrate 12 and the film 22A, electrically connecting the circuit (wiring 23 in this case) on the film 22A to a plurality of terminals 13 on the glass substrate 12.

[0019] The liquid crystal display device 100A further includes a moisture-proof resin portion 42A formed to contact the glass substrate 12, the glass substrate 14, and the film 22A. The moisture-proof resin portion 42A is formed closer to the glass substrate 14 than the anisotropic conductive resin layer 32, and has a first portion 42a between the glass substrate 12 and the film 22A, a second portion 42b between the glass substrate 14 and the film 22A, and a third portion 42c on the surface of the film 22A opposite to the surface on which the anisotropic conductive resin layer 32 is formed. The first portion 42a, the second portion 42b, and the third portion 42c are integrally formed. Here, the integral formation of the first portion 42a, the second portion 42b, and the third portion 42c means that no interface is formed between these portions.

[0020] The film 22A has a through hole 22h, and the moisture-proof resin portion 42A has a fourth portion 42d formed within the through hole 22h. The fourth portion 42d is integrally formed with the first portion 42a and the third portion 42c. As will be illustrated later, the fourth portion 42d may be omitted (see, for example, Figure 5).

[0021] The liquid crystal display device 100A has a moisture-proof resin portion 42A having at least a first portion 42a, a second portion 42b, and a third portion 42c, and these are integrally formed, thereby improving the adhesive strength between the film 22A and the glass substrate 12. The moisture-proof resin portion 42A can, of course, suppress and prevent moisture from entering the anisotropic conductive resin layer 32.

[0022] Next, the manufacturing method of the liquid crystal display device 100A will be described with reference to Figures 3 and 4. Figure 3 is a schematic cross-sectional view showing a flexible circuit board 20A used in the manufacturing of the liquid crystal display device 100A with a moisture-proof resin material 42R applied to it, and Figure 4 is a schematic plan view showing a flexible circuit board 20A with a moisture-proof resin material 42R applied to it.

[0023] The liquid crystal display device 100A may be manufactured, for example, by the following method.

[0024] First, as shown in Figure 3, a flexible circuit board 20A is prepared in which a moisture-proof resin material 42R is applied to a region on the film 22A where the first portion 42a of the moisture-proof resin part 42A is formed. If the moisture-proof resin material 42R is solid, as shown in Figure 3, it may be applied so as to protrude from the end face of the film 22A facing the side surface of the glass substrate 14, or it may be applied so as to be flush with the end face of the film 22A facing the side surface of the glass substrate 14.

[0025] Next, an anisotropic conductive resin material is placed on the terminal region of the glass substrate 12. This can be done by known methods. For example, an ACF (Acoustic Carbon Fiber) having a layer of anisotropic conductive resin material (a material in which conductive particles are dispersed in a thermosetting resin) formed on a separator fill is placed on the terminal region of the glass substrate 12 using a roll, and the separator is peeled off.

[0026] Next, with the flexible circuit board 20A positioned so that the circuits (exposed portions of the wiring 23) and the multiple terminals 13 on the glass substrate 12 are electrically connected via the anisotropic conductive resin material, the flexible circuit board 20A is thermocompressed to the glass substrate 12. Thermocompression is performed by pressing a thermocompression head into a predetermined position. At this time, the anisotropic conductive resin material hardens, and an anisotropic conductive resin layer 32 is formed. At the same time, the moisture-proof resin material 42R melts and flows, passing from between the film 22A and the glass substrate 12, to between the film 22A and the glass substrate 14, and further to the surface of the film 22A opposite to the surface where the anisotropic conductive resin layer 32 is formed. It also flows into the through-hole 22h of the film 22A and reaches the surface of the film 22A opposite to the surface where the anisotropic conductive resin layer 32 is formed. In this way, a moisture-proof resin portion 42A having at least a first portion 42a, a second portion 42b, and a third portion 42c is integrally formed.

[0027] By providing through-holes 22h as pathways for the moisture-proof resin material 42R to flow, the moisture-proof resin material 42R can easily flow to the surface of the film 22A opposite to the surface where the anisotropic conductive resin layer 32 is formed. This prevents the moisture-proof resin material 42R from flowing excessively between the film 22A and the glass substrate 14, thus preventing the moisture-proof resin portion 42 from reaching the glass substrate 14.

[0028] Preferably, the through-hole 22h has a shape that tapers toward the glass substrate 14 when viewed from the direction normal to the film 22A. For example, as illustrated here, by making the shape pointed toward the direction in which the moisture-proof resin material 42R flows out, the moisture-proof resin material 42R that flows out from the through-hole 22h and the moisture-proof resin material 42R that flows from between the glass substrate 14 and the film 22A can be easily integrated on the film 22A. The shape on the opposite side of the through-hole 22h may be an arc, for example, as illustrated here.

[0029] A commercially available ACF can be used as the ACF. The ACF consists of an anisotropic conductive resin material formed in a film on a separator (e.g., a PET film). The anisotropic conductive resin material is, for example, a thermosetting acrylic resin in which nickel particles (particle size: 2 μm to 3 μm) or metal-coated plastic particles (4 μm, 5 μm, or 10 μm) are dispersed. The thickness of the anisotropic conductive resin material is, for example, about 10 μm, and the width is, for example, about 1.5 mm to 1.7 mm, and it is used in a form that is longer than the length of the edge of the film 22A (e.g., 40 mm to 45 mm).

[0030] A thermosetting acrylic resin can be used as the moisture-proof resin material. A thermosetting acrylic resin with moisture-proof properties that is widely used in electronic components can be used. The moisture-proof resin material is applied along the edge of the film 22A, for example, in a width of 1.5 mm to 2.0 mm.

[0031] The heating and pressing conditions for the thermocompression head are, for example, temperature: 150°C to 210°C, pressure: 2 MPa to 7 MPa, and time: 4 seconds to 15 seconds. These can be adjusted by changing the type of acrylic resin.

[0032] The through-holes 22h formed in the film 22A are, for example, 1.0 mm or larger in area equivalent diameter. The diameter is 1.5 mm or less. Furthermore, it is preferable that the total area of ​​the multiple through holes 22h is formed to be, for example, 50% to 75% of the area of ​​the moisture-proof resin material applied beneath the film 22A (for example, width (1.5 mm to 2.0 mm) × length (40 mm to 45 mm)). If the total area of ​​the multiple through holes 22h is less than 50% or more than 75%, the integral formation of the moisture-proof resin part 42A may be insufficient, and the effect of improving the adhesive strength of the film 22A may not be fully obtained.

[0033] In the above-described manufacturing method for the liquid crystal display device 100A, the anisotropic conductive resin layer 32 and the moisture-proof resin part 42A can be formed in the same process, so mass production efficiency is not reduced.

[0034] Next, an embodiment of the liquid crystal display device 100B of the present invention will be described with reference to Figures 5 to 7. Components with the same function are indicated by common reference numerals, and their descriptions may be omitted.

[0035] Figure 5 is a schematic cross-sectional view of the liquid crystal display device 100B, and Figure 6 is a schematic plan view of the liquid crystal display device 100B. Figure 5 corresponds to the cross-section along the line V-V' in Figure 6. Figure 7 is a schematic plan view showing the flexible circuit board 20B used in the manufacture of the liquid crystal display device 100B with the moisture-proof resin material 42R applied to it.

[0036] As shown in these figures, a flexible circuit board 20B can be used instead of the flexible circuit board 20A in the liquid crystal display device 100A.

[0037] The flexible circuit board 20B does not have the through-hole 22h of the flexible circuit board 20A. Instead, the flexible circuit board 20B has a notch 22j on the end face facing the side of the glass substrate 14, and the second portion 42b of the moisture-proof resin portion 42B includes a portion that penetrates the notch 22j. The notch 22j has a shape of connected triangles, but is not limited to this. The size of the notch 22j is, for example, 0.7 mm to 1.4 mm, and it is preferable that the total area of ​​the notch 22j is formed to be, for example, 50% to 75% of the area of ​​the moisture-proof resin material applied under the film 22A (for example, width (1.5 mm to 2.0 mm) × length (40 mm to 45 mm)). If the total area of ​​the notch 22j is less than 50% or more than 75%, the integral formation of the moisture-proof resin portion 42A may be insufficient, and the effect of improving the adhesive strength of the film 22A may not be fully obtained.

[0038] The shape of the notch is not limited to the above example. For example, the notch 22k may have a shape that tapers toward the glass substrate 14 when viewed from the normal direction of the film 22C, as shown in Figure 8 for the flexible circuit board 20C. [Industrial applicability]

[0039] According to embodiments of the present invention, an electronic device such as a display device with excellent moisture resistance and adhesive strength in a structure in which an FPC is connected to an electronic element substrate using ACF is provided, as well as a method for manufacturing the same. [Explanation of symbols]

[0040] 10: LCD display panel 12: Glass substrate, active matrix substrate 13: Terminals 14: Glass substrate, opposing substrate 20A: Flexible circuit board 22A: Film 22h: Through hole 22j: Notch 22k: Notch 23: Wiring 24: Driver IC 32: Anisotropic conductive resin layer 42A: Moisture-proof resin part 42a: Part 1 42b :Second part 42c: 3rd part 42d: 4th part 100A: Liquid crystal display device

Claims

1. An electronic element substrate comprising a first substrate, a plurality of electronic elements formed on the first substrate, and a plurality of wirings connected to the plurality of electronic elements, A second substrate is placed on the first substrate so as to expose the terminal region where the multiple terminals of the multiple wirings of the first substrate are formed, A flexible circuit board having a flexible film and a circuit provided on the film, An anisotropic conductive resin layer is disposed between the terminal region of the first substrate and the film to electrically connect the circuit and the plurality of terminals. It has, The first substrate, the second substrate, and the film further comprise a moisture-proof resin portion formed to be in contact with each other. The moisture-proof resin portion is formed closer to the second substrate than the anisotropic conductive resin layer, and the moisture-proof resin portion has a first portion between the first substrate and the film, a second portion between the second substrate and the film, and a third portion on the surface of the film opposite to the surface on which the anisotropic conductive resin layer is formed, and the first portion, the second portion and the third portion are formed continuously, in an electronic device.

2. The film has through holes, The moisture-proof resin portion further has a fourth portion formed within the through hole, The electronic device according to claim 1, wherein the fourth part is integrally formed with the first part and the third part.

3. The electronic device according to claim 2, wherein the through hole has a shape that tapers toward the second substrate when viewed from the direction normal to the film.

4. The film has a notch at the end face facing the side of the second substrate. The electronic device according to claim 1, wherein the second portion includes a portion that enters the notch.

5. A method for manufacturing an electronic device according to any one of claims 1 to 4, Step A is to prepare a flexible circuit board in which a moisture-proof resin material is applied to the region on the film where the first portion of the moisture-proof resin part is formed, Step B involves placing an anisotropic conductive resin material on the terminal region of the first substrate, Step C involves heat-pressing the flexible circuit board to the first substrate in a state in which the circuit of the flexible circuit board and the plurality of terminals on the first substrate are arranged to be electrically connected via the anisotropic conductive resin material. It includes, A manufacturing method comprising the steps C above, in which the anisotropic conductive material is cured to form the anisotropic conductive resin layer, and the moisture-proof resin material is melted, flowed, and cured to form the moisture-proof resin portion.

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