JP2006056995A - Adhesive sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive sheet capable of improving the accuracy of the stuck position of a sheet for LSI, FPC or the like, enabling an installed area to be reduced and enabling a sticking process to be reduced when installing two or more kinds of circuit boards on a substrate. <P>SOLUTION: The adhesive sheet is used for installing the two or more circuit boards on the substrate, and is constituted by connecting and integrating two or more sheets. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to an adhesive sheet. More specifically, the present invention relates to an adhesive sheet composed of an anisotropic conductive film used for mounting a circuit board on a substrate.

An adhesive sheet for mounting a circuit board on a substrate is indispensable in COG (chip on glass) technology for manufacturing a liquid crystal display device. For example, a liquid crystal panel terminal Is used to mount a semiconductor substrate such as an integrated circuit chip (LSI), a flexible printed circuit board (FPC), or the like.
In the conventional COG technique, an ACF (anisotropic conductive film) is formed on a panel made of a glass substrate by a process as shown in FIG. 5 in order to produce a panel terminal portion as shown by a dotted line in FIG. LSI and FPC were bonded together using Specifically, first, an ACF for COG is attached (temporary pressure bonding). Next, an LSI is mounted and an ACF for FPC is attached (temporary pressure bonding). Finally, the FPC was crimped.

However, in the conventional mounting method, when mounting a plurality of types of circuit boards on the substrate using the ACF that is an anisotropic conductive film, the ACF for mounting the plurality of types of circuit boards on the substrate is a separate process. It was affixed and temporarily crimped. For example, when an LSI and an FPC are attached by ACF in a panel terminal portion of a liquid crystal display device, the LSI ACF and the APC for FPC are temporarily bonded in separate steps. For this reason, it is necessary to perform alignment twice in order to bond the two ACFs. Such double alignment causes variations in the individual mounting positions of the LSI and FPC ACFs.

By the way, the following apparatuses and members are disclosed regarding the technique of mounting a circuit board on a board | substrate. That is, an electro-optical device in which an integrated circuit chip is conductively connected to a wiring pattern via an anisotropic conductive film, and the anisotropic conductive film is formed so as to cover the connection wiring portion (for example, see Patent Document 1). .) Is disclosed. In this apparatus, the integrated circuit chip and the electric element are mounted on the substrate by an integral anisotropic conductive film, and the electric element is electrically connected to the integrated circuit chip. In addition, a liquid crystal display device having a conductive adhesive for connecting a protruding electrode of a semiconductor device, a transparent electrode arranged on a substrate, and a flexible printed circuit (for example, see Patent Document 2), an insulating adhesive. An anisotropic conductive adhesive sheet in which conductive particles are dispersed and mixed, a first protective sheet that is detachably attached to one surface of the anisotropic conductive adhesive sheet, and the anisotropic conductive adhesive sheet An anisotropic conductive member (for example, refer to Patent Document 3) including a second protective sheet that is detachably attached to the other surface is disclosed.

Further, a display device (for example, a semiconductor IC chip and a second connection portion of a flexible wiring board are mounted on the surface of the substrate overhanging portion with an integral anisotropic conductive film attached thereto. Patent Document 4) is disclosed. Also in this apparatus, the semiconductor IC chip and the second connection portion of the flexible wiring board are mounted on the substrate by an integral anisotropic conductive film. The anisotropic conductive film is connected to the semiconductor IC chip and the flexible wiring. Even after the second connection portion of the substrate is mounted on the substrate, it remains integral, and the semiconductor IC chip and the second connection portion of the flexible wiring substrate are connected via the anisotropic conductive film.

However, these devices cannot be configured so that a plurality of types of circuit boards are not connected via an anisotropic conductive film. Accordingly, in a production factory that performs a process of mounting a plurality of types of circuit boards on a substrate using a sheet of ACF or the like, it is possible to reduce the steps of attaching these plurality of types of circuit boards and provisional pressure bonding, and a plurality of types. The circuit board can be pasted on the board in the same state as pasting using a separate sheet of ACF, etc., and the position accuracy of individual sheets on which multiple types of circuit boards are pasted is improved. As a result, there was room for improvement so that a high-quality and high-quality product could be manufactured.
JP 2001-242799 A (pages 1 and 2) Japanese Utility Model Publication No. 7-32953 (Pages 1, 2) JP-A-6-333623 (page 1-4) JP 2002-305220 A (pages 1, 2, 7-9)

The present invention has been made in view of the above situation, and when mounting a plurality of types of circuit boards on a substrate, it is possible to improve the accuracy of sheet pasting positions for LSIs, FPCs, etc. An object of the present invention is to provide an adhesive sheet that can be reduced in size and can reduce the attaching process.

The inventors of the present invention have studied various types of adhesive sheets used for mounting a plurality of types of circuit boards on a substrate, and have focused on the fact that separate sheets are used for attaching a plurality of types of circuit boards. By integrating these individual sheets, for example, the ACF for COG and the ACF for FPC are integrated and pasted to the panel terminal part, so that the ACF for FPC at the production factory is pasted, and It is possible to reduce the temporary crimping process, improve the production capacity, and paste a plurality of types of circuit boards on the board in the same state as pasted using separate sheets of ACF or the like. It has been found that the variation in the accuracy of the ACF attachment position can be suppressed, and the inventors have conceived that the above problems can be solved brilliantly, thereby reaching the present invention. Those were.
Note that the prior art requires a slight margin between the two ACFs in order to prevent the two ACFs from overlapping. In the present invention, by integrating both ACFs, the mounting area can be reduced by eliminating the margin between the ACFs.

That is, it is an adhesive sheet used for mounting a plurality of types of circuit boards on a substrate, and the adhesive sheet is an adhesive sheet formed by connecting and integrating a plurality of sheets.
The plurality of sheets preferably have different compositions. For example, the said several sheet | seat includes the form containing the 1st sheet | seat which has a 1st composition, and the 2nd sheet | seat which has a 2nd composition. Thereby, the composition of an adhesive sheet can be adjusted according to multiple types of circuit boards.

After the adhesive sheet is attached to the substrate, the region in the vicinity of the boundary between the first sheet and the second sheet can be peeled off from the substrate in a band shape, so that it can be temporarily pressure-bonded, The circuit board attached by the first sheet and the circuit board attached by the second sheet can be electrically separated. In this case, it is preferable that the adhesive sheet has a perforation at the boundary between the strippable region and the first sheet and at the boundary between the strippable region and the second sheet.

The adhesive sheet further includes a protective sheet that can be peeled off on one side of a plurality of sheets, so that the adhesive sheet is attached to the substrate or the circuit board is attached to the adhesive sheet. Can protect the sheet up to. The protective sheet is bonded to the surface on the side opposite to the surface to be bonded to the substrate in a peelable state on the surface to which the circuit board is bonded.
In this case, the protective sheet can be peeled separately from the part formed on the first sheet and the part formed on the second sheet, and the protective sheet is attached to the substrate. After being formed, it is preferable to include a strip-like portion that can be peeled together with a strip-like peelable region in the vicinity of the boundary between the first sheet and the second sheet.

In addition, the protective sheet is bonded to the second sheet and the first partial protective sheet bonded to the first sheet, the region that can be peeled off in the vicinity of the boundary between the first sheet and the second sheet, and the first sheet. The first partial protective sheet is peeled off together with the strippable area in the vicinity of the boundary between the first sheet and the second sheet after being attached to the substrate. By being possible, it is possible to peel the strippable region together with the protective sheet on the first sheet, and to reduce the number of steps in the production process.

In the adhesive sheet, the first sheet includes a larger amount of conductive particles than the second sheet, and the adhesive sheet includes the first sheet and the second sheet that include conductive particles. The diameter of the conductive particles contained in the sheet is smaller than the diameter of the conductive particles contained in the second sheet, so that the electrical characteristics of the sheet are optimized according to the electrode area of the circuit board attached on the adhesive sheet. be able to. Furthermore, the said adhesive sheet can adjust the physical property of a sheet | seat by the thermal expansion coefficient etc. of an adhesive sheet or a circuit board, when a 2nd sheet contains a larger amount of rubber particles than a 1st sheet | seat.

The adhesive sheet of the present invention is suitable for mounting an LSI, an FPC, or the like on a liquid crystal panel terminal in COG technology for manufacturing a liquid crystal display device. That is, the plurality of types of circuit boards preferably include a semiconductor substrate and a flexible printed board. In this case, the semiconductor substrate is attached to the first sheet, and the flexible printed board is attached to the second sheet.

A liquid crystal display device formed using the adhesive sheet is also one aspect of the present invention.
The configuration of the adhesive sheet or the liquid crystal display device of the present invention is not particularly limited as long as it includes the above-described components as essential, and may include other components.

According to the adhesive sheet of the present invention, when a plurality of types of circuit boards are mounted on the board, the sheet attaching position accuracy can be improved, the mounting area can be reduced, and the attaching process in the production factory And the provisional crimping process can be reduced. For example, when a circuit board such as an LSI or FPC is mounted on the panel terminal portion of the display device using an ACF, the process of attaching the COG ACF and the FPC ACF and provisional pressure bonding can be reduced, thereby improving the production capacity. Therefore, it is possible to suppress variations in the accuracy of the ACF attachment position.

In the following, an example embodied in an adhesive sheet will be described as the best mode for carrying out the present invention, and will be described in more detail with reference to the drawings. However, the present invention is limited only to these embodiments. is not.
In the present embodiment, an example in which an LSI and an FPC are mounted using an adhesive sheet as an ACF in a panel terminal portion of a liquid crystal display device is shown.
The adhesive sheet in the present embodiment is configured such that a plurality of sheets are connected so as to form a common surface, but as long as the plurality of sheets are connected and integrated. It is not particularly limited.

(First embodiment)
FIG. 1-1 is a schematic diagram illustrating a configuration of an adhesive sheet of the present embodiment.
In FIG. 1-1, the 1st sheet | seat (1) and the 2nd sheet | seat (2) are joined through the slit (4) of a strip | belt-shaped area | region. The slit (4) can be peeled off from the substrate after the adhesive sheet is attached to the substrate.
The first sheet (1) and the second sheet (2) may be joined side by side, but in this way near the boundary between the first sheet (1) and the second sheet (2). It is preferable to provide a band-like region (4) in the region. Such an adhesive sheet is used for mounting a plurality of types of circuit boards on the main surface of the glass substrate.

On one main surface of the first sheet (1) and the second sheet (2), a protective sheet (film) bonded in a peelable state is overlaid, and the main sheet of the first sheet (1) is overlapped. The portion (3) formed on the surface and the portion (3 ') formed on the main surface of the second sheet are in a state where they can be separated separately. In addition, two perforations (5) are inserted in the vicinity of the boundary between the first sheet (1) and the second sheet (2), whereby the first sheet (1) and the second sheet (2) The sheet (4) in the vicinity of the boundary with the second sheet (2) and the protective sheet (4 ') overlapping this portion can be peeled off. Thus, after the protective sheet is attached to the substrate, the protective sheet has a strip-like shape that can be peeled together with the strip-like region (4) in the vicinity of the boundary between the first sheet (1) and the second sheet (2). The part (4 ') is included, and the region (4 and 4') in the vicinity of the boundary between the first sheet (1) and the second sheet (2) can be peeled off from the substrate after being attached to the substrate. It has become.

In the embodiment, the protective sheet is conceptually colored so that it can be easily understood that the protective sheet is bonded to the first sheet or the second sheet. In this embodiment, the protective sheet is divided into three parts (3), (4 '), and (3') by two perforations (5) in FIG. 1-1.

In the adhesive sheet of the present embodiment, the portion of the sheet to which the LSI is bonded contains a large amount of conductive particles. On the other hand, the amount of conductive particles in the sheet to which the FPC is bonded is smaller than that of the sheet to which the LSI is bonded. This is because the area where the LSI is mounted has a smaller electrode area. In addition, the diameter of the conductive particles included in the sheet to which the LSI is bonded is desirably smaller than the conductive particles included in the sheet to which the FPC is bonded. For example, the diameter of the conductive particles included in the sheet to which the LSI is bonded is 3 to 5 μm, and the diameter of the conductive particles included in the sheet to which the FPC is bonded is 5 to 10 μm. Is preferred.
As the conductive particles, for example, metal particles, carbon particles, or plastic particles obtained by performing metal plating can be used.

Further, the adhesive sheet of the present embodiment may contain rubber particles. This is because when the rubber particles are mixed, the expansion coefficient of the sheet is lowered. Here, the thermal expansion coefficient of the adhesive sheet is larger than that of LSI or FPC. For this reason, there is a risk that the LSI or the like may warp due to a difference in thermal expansion coefficient during heating. In order to sufficiently suppress such a phenomenon, it is preferable to mix rubber particles. Since LSI has a smaller thermal expansion coefficient than FPC, the amount of rubber particles in the adhesive sheet on the side where the LSI is bonded is smaller than that on the adhesive sheet on the side where the LSI is bonded.

Note that the material and the like of the first sheet and the second sheet are not particularly limited, and may be any material that normally constitutes the ACF. For example, a resin substrate in which conductive particles are dispersed can be used. The thickness is preferably 18 to 25 μm. Further, the protective sheet may be any sheet that is normally used as a protective sheet for ACF. For example, an inorganic sheet, an organic sheet such as polyimide resin, a sheet having a laminated structure of these inorganic sheet and organic sheet, or the like is used. The thickness is preferably 30 to 50 μm.

Below, FIG. 1-2 is used and the one form of the usage method of the adhesive sheet in this embodiment is demonstrated.
FIG. 1-2 is a conceptual diagram illustrating a process of sequentially bonding LSIs and FPCs using the adhesive sheet illustrated in FIG. 1-1, and is a view of the panel terminal portion as viewed from above.
First, as shown in (a), the adhesive sheet is temporarily pressure-bonded in a state of being aligned with a predetermined position of the glass substrate. Next, as shown in (b), the adhesive sheet corresponding to the central boundary part (9) of the adhesive sheet and the protective sheet of this part are peeled off together, and then the first sheet as shown in (c) Remove the protective sheet in the lower area (10) corresponding to. Thereafter, as shown in (d), the LSI (11) is pressure-bonded to the area (10) from which the protective sheet has been peeled, and then, as shown in (e), the upper area (8) corresponding to the second sheet. ) Is removed. Finally, as shown in (f), the FPC (12) is pressure-bonded to the region (8) from which the protective sheet has been peeled off. Through the above process, the LSI and the FPC are bonded together. Thereby, a semiconductor substrate is affixed on a 1st sheet | seat, and a flexible printed circuit board is affixed on a 2nd sheet | seat.
Note that the substrate is preferably a glass substrate, but is not limited thereto, and a material for forming the substrate may be appropriately selected depending on the application.

In this embodiment, the accuracy of attaching individual ACFs for LSI and FPC is improved and the mounting area is reduced as compared with the conventional form as shown in FIG. Further, the attaching process can be reduced.
A panel terminal unit and a method for manufacturing a liquid crystal display device by a bonding process as shown in the present embodiment, and a liquid crystal display device manufactured by the manufacturing method are examples of a preferred embodiment of the present invention.

(Second Embodiment)
FIG. 2-1 is a schematic diagram illustrating a configuration of the adhesive sheet of the present embodiment.
In FIG. 2A, the first sheet (1) and the second sheet (2) are joined through the slit (4) in the band-like region. The slit (4) can be peeled off from the substrate after the adhesive sheet is attached to the substrate. A protective sheet (film) (3) is overlaid on the main surfaces of the first sheet (1) and the second sheet (2). Further, one perforation (5) is provided in the vicinity of the boundary between the first sheet (1) and the second sheet (2). As a result, the adhesive sheet in the vicinity (4) of the boundary between the first sheet (1) and the second sheet (2) and the protective sheet in the region (6) in FIG. Can be done. As described above, the protective sheet of the present embodiment covers the strip-like peelable region (4) and the first sheet (1) in the vicinity of the boundary between the first sheet (1) and the second sheet (2). The first partial protective sheet (6) and the second partial protective sheet (6 ') bonded so as to cover the second sheet (2), the first partial protective sheet (6) can be peeled together with the strip-like peelable region (4) in the vicinity of the boundary between the first sheet (1) and the second sheet (2) after being attached to the substrate.
Other configurations and compositions are the same as those in the first embodiment.
Also in this embodiment, the protective sheet is conceptually colored, and in FIG. 2A, the protective sheet is divided into two parts (6) and (6 ′) by one perforation (5). Will be.

Below, FIG. 2-2 is used and the one form of the usage method of the adhesive sheet in this embodiment is demonstrated.
FIG. 2-2 is a conceptual diagram illustrating a process of bonding the LSI and the FPC using the adhesive sheet illustrated in FIG. 2A and is a view of the panel terminal portion as viewed from above.
First, as shown in (a), the adhesive sheet is temporarily pressure-bonded in a state of being aligned with a predetermined position of the glass substrate. Next, as shown in (b), the protective sheet of the part ((9) and (10)) surrounded by the dotted line is peeled off. As a result, the sheet (4) of the central portion (9) is also peeled off, but the adhesive sheet at this time is in a state as shown in FIG. Thereafter, as shown in (c), the lower region (10) corresponding to the first sheet (10) LSI (11) is crimped, and then as shown in (d), the upper side corresponding to the second sheet. Remove the protective sheet in area (8). Finally, as shown in (e), the FPC (12) is pressure-bonded to the region (8) from which the protective sheet has been peeled off. Through the above process, the LSI and the FPC are bonded together.

Also in the present embodiment, the same operational effects as described above can be obtained. In this case, the attaching step can be further reduced as compared with the first embodiment.
A panel terminal portion and a liquid crystal display device manufacturing method by a bonding process as shown in the present embodiment, and a liquid crystal display device manufactured by the manufacturing method are also examples of a preferred embodiment of the present invention.

The embodiment described above is an example applied to a panel terminal portion of a liquid crystal display device, but an adhesive sheet in which a plurality of sheets are integrated is not limited to such an embodiment, but an electroluminescence (EL) display device. The present invention can be applied to various display devices such as the above and electronic / electrical devices having a process of attaching a plurality of types of circuit boards on a substrate or temporarily pressing them.

It is a schematic diagram which shows the structure of the adhesive sheet of 1st Embodiment. It is a flowchart which shows the process of bonding LSI and FPC using the adhesive sheet shown by FIGS. 1-1. It is a schematic diagram which shows the structure of the adhesive sheet of 2nd Embodiment. It is a flowchart which shows the process of bonding LSI and FPC using the adhesive sheet shown by FIGS. In the usage method of FIGS. 2-2, it is a conceptual diagram which shows the state of the adhesive sheet after passing through the process of (b). It is a conceptual diagram which shows the liquid crystal panel by which LSI and FPC are mounted. It is a flowchart which shows the process of bonding LSI and FPC using the conventional adhesive sheet.

Explanation of symbols

1: First sheet 2: Second sheet 3: Protection sheet (on the first sheet)
3 ′: Protection sheet (on the second sheet)
4: Near boundary area (slit area)
4 ': Area near the boundary of the protective sheet (slit area)
5: Perforation 6: 1st partial protection sheet 6 ': 2nd partial protection sheet 7: Glass substrate 8: Area 9: Boundary area 10: Area 11: LSI
12: FPC
13: Panel 14: ACF for COG
15: ACF for FPC
100: Adhesive sheet 200 of the first embodiment: Adhesive sheet of the second embodiment

Claims (14)

An adhesive sheet used for mounting a plurality of types of circuit boards on a substrate,
The adhesive sheet is formed by connecting and integrating a plurality of sheets. The adhesive sheet according to claim 1, wherein the plurality of sheets have different compositions. The adhesive sheet according to claim 2, wherein the plurality of sheets include a first sheet having a first composition and a second sheet having a second composition. 4. The adhesive according to claim 3, wherein after the adhesive sheet is attached to the substrate, a region in the vicinity of the boundary between the first sheet and the second sheet can be peeled off from the substrate in a band shape. Sheet. 5. The adhesive sheet is provided with perforations at a boundary between a strip-like peelable region and the first sheet and at a border between the belt-like peelable region and the second sheet. The adhesive sheet as described. The adhesive sheet according to any one of claims 1 to 5, wherein the adhesive sheet further includes a protective sheet bonded to one side of a plurality of sheets in a peelable state. The adhesive sheet according to claim 6, wherein the protective sheet is capable of separating a portion formed on the first sheet and a portion formed on the second sheet separately. The said protective sheet contains the strip | belt-shaped part which can be peeled with the area | region which can peel in strip | belt shape in the vicinity of the boundary of a 1st sheet | seat and a 2nd sheet | seat after being affixed on a board | substrate. The adhesive sheet as described. The protective sheet was bonded to the second sheet and the first partial protective sheet bonded to the first sheet and the area that can be peeled off in the vicinity of the boundary between the first sheet and the second sheet. A second partial protective sheet,
The first partial protective sheet is peelable together with a strippable region in the vicinity of the boundary between the first sheet and the second sheet after being attached to the substrate. The adhesive sheet as described. The adhesive sheet according to claim 3, wherein the first sheet includes a larger amount of conductive particles than the second sheet. In the adhesive sheet, the first sheet and the second sheet include conductive particles,
The adhesive sheet according to claim 3, wherein the diameter of the conductive particles contained in the first sheet is smaller than the diameter of the conductive particles contained in the second sheet. The adhesive sheet according to claim 3, wherein the second sheet includes a larger amount of rubber particles than the first sheet. The adhesive sheet according to any one of claims 1 to 12, wherein the plurality of types of circuit boards include a semiconductor substrate and a flexible printed circuit board. A liquid crystal display device comprising the adhesive sheet according to claim 1.

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