JPH06186577A - Anisotropically conductive connecting structure - Google Patents

Abstract

PURPOSE:To provide the connecting structure and method for circuits which narrow the connecting part of the anisotropically conductive connecting structure as much as possible and have excellent reliability on moisture resistance. CONSTITUTION:The anisotropically conductive connecting structure having the excellent reliability on moisture resistance is obtd. by connecting a conductive circuit part 3 formed on a substrate 1 and a conductive circuit part 4 formed on a substrate 2 over the entire surface of the opposite part 5 thereof by using an adhesive which is prepd. by dispersing conductive particulates 7 into a dispersion medium 6, such as UV curing type adhesive, then subjecting this part to irradiation with UV rays simultaneously with pressurizing to substantially shield the parts facing each other of the circuits for connection from moisture by the dispersion medium 6 and applying a silicone resin to the exposed conductive parts exclusive of the parts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an anisotropic conductive connection structure,
In particular, it relates to a highly reliable connection structure of a liquid crystal display device using a flexible connection circuit board on which a plurality of terminals are arranged.

[0002]

2. Description of the Related Art Electrical connection and fixing between a liquid crystal display element constructed by using a polymer film substrate adapted for high capacity, light weight and thinness of a liquid crystal display panel and a drive circuit board such as a tape carrier type semiconductor device. It is known that connection failure frequently occurs in the connection part for.

The following are conventional techniques for improving the reliability of the connection with the external circuit. In JP-A-1-28621 and JP-A-2-29628, an attempt is made to improve the electrical reliability by providing a dummy electrode or increasing the terminal area of the outermost end of the connection terminal. In JP-A-2-82222, it is intended to improve the moisture resistance reliability by extending the alignment film to the heat-sealed portion.

[0004]

However, among the above-mentioned conventional techniques, the former can be evaluated as a measure for improving the initial yield at the time of connection and a measure for improving mechanical and electrical reliability. Had a problem that it had no effect. On the other hand, the latter has some effect on the moisture resistance reliability, but since the alignment film generally has a film thickness of only a few hundred angstroms, it is insufficient in applications where moisture resistance reliability is important. In the portion where the film overlaps with the heat-sealed portion, the alignment film has an insulating property, so that the area that contributes to the electrical connection is substantially reduced, and there is a problem that the electrical characteristics may be sacrificed. Further, particularly in a liquid crystal display device, there is a demand to make the portion other than the display portion as small as possible, and a circuit connection structure and method that satisfy this demand are desired.

The present invention has been made in view of the above problems, and in order to meet the above demands, the present invention is
It is an object of the present invention to provide a circuit connection structure and method that have a connection area that is as small as possible and that has excellent moisture resistance reliability.

[0006]

In order to achieve the above object, in the anisotropic conductive connection structure of the present invention, connecting circuit boards formed to face each other for connecting to an external circuit face each other. It is characterized in that the entire surface is adhesively connected.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be described below with reference to the drawings. In all the drawings for explaining the conventional example and the embodiment, the same reference numerals are given to those having the same function.

Conventional Example FIG. 9 shows an example of a conventional anisotropic conductive connection structure. (A)
Is a plan view and (b) is a cross-sectional view. The conductive circuit portion 3 formed on the substrate 1 and the conductive circuit portion 4 formed on the substrate 2 are anisotropically conductively connected by a part 5 of the facing portion.

FIG. 10 shows details of the anisotropically conductive connecting portion.
The anisotropic conductive connection is usually a dispersion medium 6 such as a synthetic rubber resin.
Electrically conductive fine particles 7 are dispersed in the conductive fine particles 7, and the conductive fine particles 7 are sandwiched between the connecting circuits having the conductors to be connected and heated under pressure to electrically connect the conductive fine particles. When a high temperature and high humidity test at 60 ° C. and 90% RH was carried out with such a structure, it was found that corrosion occurred in the exposed conductor portion other than the anisotropic conductive connection portion 5 in FIG.

Here, in order to improve the moisture resistance, it is common to shield the moisture by protecting the conductor portion with a moisture resistant material. In order to improve the moisture resistance, we tried to shield the entire structure of FIG. 9 from moisture with a sealant such as silicone resin, and subjected it to a high temperature and high humidity test. I have found that it cannot be prevented. It is considered that this is because the sealant does not enter this portion.

Embodiment 1 FIG. 1 shows an embodiment of the invention corresponding to claim 1. Note that (a) is a plan view and (b) is a cross-sectional view. The conductive circuit portion 3 formed on the substrate 1 and the conductive circuit portion 4 formed on the substrate 2 are anisotropically conductively connected to each other on the front surface of the facing portion 5. Details of the anisotropic conductive connection portion are as shown in FIG. Here, in the case where anisotropic conductive connection that does not require heating is performed, an ultraviolet curable adhesive such as an acrylic or polyurethane adhesive is used as the dispersion medium 6, and ultraviolet irradiation may be performed simultaneously with pressurization.

By adopting the anisotropic conductive connection structure shown in FIG. 1, silicone resin is applied to the conductor portions which are substantially exposed by the dispersion medium 6 at the opposite portions of the connection circuit.
When subjected to a high temperature and high humidity test (60 ° C, 90% RH),
It was confirmed that there was no deterioration.

Embodiment 2 Further, in FIG. 1, when a flexible substrate such as polyethylene terephthalate, polycarbonate, polyarylate or polyimide is used as the connecting circuit boards 1 and 2, the same effect as the above is obtained. . (Corresponding to claim 2)

Embodiment 3 FIG. 2 shows an embodiment of the invention corresponding to claim 3. The liquid crystal display unit includes a transparent substrate 2 having a transparent conductive thin film electrode 4.
And a transparent substrate 8 having a transparent conductive thin film electrode (not shown) are bonded together with the transparent conductive thin film electrode inside, and the peripheral portion is sealed with a sealing material 9 made of epoxy resin or the like. The bag-shaped portion is filled with the liquid crystal 10. (In order to function as a liquid crystal display device, an alignment film for aligning the liquid crystal, a spacer for keeping the thickness of the liquid crystal constant, a polarizing plate for regulating the polarization characteristics, etc. are required at predetermined places. , Not described here.)

In the third aspect, the transparent conductive thin film electrode 4 formed on one of the substrates 2 constituting the liquid crystal display device and the circuit substrate 1 for electrically connecting to an external circuit are formed. The entire surface of the opposing portion 5 is anisotropically conductively connected to the formed conductive circuit portion 3, and the end portion of the other transparent substrate 8 constituting the liquid crystal display device and the external circuit are formed. The end portion of the circuit board 1 for electrically connecting with the above has a structure abutting as shown in the drawing. Details of the anisotropic conductive connection portion are as shown in FIG.

In the case of anisotropic conductive connection which does not require heating, an ultraviolet-curable adhesive such as acrylic or polyurethane is used as the dispersion medium 6, and ultraviolet irradiation may be performed simultaneously with pressurization.

It has been found from the above-mentioned high temperature and high humidity test that, by using the anisotropic conductive connection structure shown in FIG. 1, the opposing portions of the connection circuit can substantially shield moisture by the dispersion medium 6. The liquid crystal display device side is filled with liquid crystal with the electrode part inside, and the peripheral part of the liquid crystal display device is sealed with a sealing material such as epoxy resin, and is anisotropically conductive with the sealing material. Since the connecting portion is joined, the liquid crystal display device including the anisotropic conductive connecting portion is substantially shielded from moisture as a whole and is formed on the circuit board 1 for electrically connecting to an external circuit. The conductor portion of only the portion of the conductive circuit portion 3 which does not contribute to the anisotropic conductive connection is not exposed (for example, the anisotropic conductive adhesive may be formed on the entire surface) or is exposed. Such as applying silicone resin to the conductor Subjected to physical, high-temperature high-humidity test (60 ° C.,
When subjected to 90% RH), it was confirmed that there was no deterioration.

Embodiment 4 Also, in FIG. 2, the same effect as above can be obtained when a flexible substrate such as polyethylene terephthalate, polycarbonate, polyarylate or polyimide is used as the connecting circuit boards 1 and 2. . (Corresponding to claim 4)

Embodiment 5 FIG. 3 shows an embodiment of the invention corresponding to claim 5. Board 1
The conductive circuit portion 3 formed above and the conductive circuit portion 4 formed on the substrate 2 are anisotropically conductively connected over the entire surface of the facing portion 5. Here, as shown in the drawing, the width of the electrode that requires connection at the end of the connection portion was formed wider than the other portions.

Generally, at the end of such a connecting portion, burrs of the substrate appear, and even if an attempt is made to apply a uniform pressing force for connection, the pressing force applied to the end is applied to other portions. It has been found that the pressure becomes larger than the applied pressure, and in particular, in the case of the transparent conductive thin film electrode 4 formed on the flexible substrate 2, cracks may occur and lead to disconnection.

As in the present embodiment, the width of the electrode that needs to be connected at the end of the connecting portion is made 10% or more wider than the other portions, so that the above-mentioned disconnection at the time of pressurization is effectively prevented. We were able to.

The details of the anisotropic conductive connection portion are as shown in FIG. Here, in the case where anisotropic conductive connection that does not require heating is performed, an ultraviolet curable adhesive such as an acrylic or polyurethane adhesive is used as the dispersion medium 6, and ultraviolet irradiation may be performed simultaneously with pressurization.

It has been found from the above-mentioned high temperature and high humidity test that the opposing portions of the connecting circuit can substantially block moisture by the anisotropic conductive connecting structure shown in FIG. , Does not expose the conductor portion of only the portion of the conductive circuit portion 3 formed on the circuit board 1 for electrically connecting with an external circuit that does not contribute to anisotropic conductive connection (for example, anisotropic Conductive adhesive may be formed on the entire surface.) The exposed conductor part is subjected to a treatment such as applying a silicone resin, and subjected to a high temperature and high humidity test (60 ° C., 90% R
When subjected to H), it was confirmed that there was no deterioration.

Embodiment 6 FIG. 4 shows an embodiment of the invention corresponding to claim 6. Board 1
The conductive circuit portion 3 formed above and the conductive circuit portion 4 formed on the substrate 2 are anisotropically conductively connected over the entire surface of the facing portion 5. Here, as shown in the figure, the electrode that requires connection at the end of the connection portion was divided into two and formed.

Generally, at the end of such a connecting portion, burrs of the substrate are exposed, and even if an attempt is made to apply a uniform pressing force for connection, the pressing force applied to the end is applied to the other portions. It has been found that the pressure becomes larger than the applied pressure, and in particular, in the case of the transparent conductive thin film electrode 4 formed on the flexible substrate 2, cracks may occur and lead to disconnection.

By forming the electrode which requires connection at the end portion of the connection portion by dividing it into two or more pieces as in the present embodiment, even if one of the electrodes is broken during the above-mentioned pressurization It was confirmed experimentally that there were few ripples, and it was possible to effectively prevent the yield reduction due to disconnection.

Details of the anisotropically conductive connecting portion are as shown in FIG. Here, in the case where anisotropic conductive connection that does not require heating is performed, an ultraviolet curable adhesive such as an acrylic or polyurethane adhesive is used as the dispersion medium 6, and ultraviolet irradiation may be performed simultaneously with pressurization.

Since it has been found by the above-mentioned high temperature and high humidity test that the opposing portions of the connection circuit can substantially shield moisture by using the anisotropic conductive connection structure shown in FIG. , Does not expose the conductor portion of only the portion of the conductive circuit portion 3 formed on the circuit board 1 for electrically connecting with an external circuit that does not contribute to anisotropic conductive connection (for example, anisotropic Conductive adhesive may be formed on the entire surface.) The exposed conductor part is subjected to a treatment such as applying a silicone resin, and subjected to a high temperature and high humidity test (60 ° C., 90% R
When subjected to H), it was confirmed that there was no deterioration.

Embodiment 7 FIG. 5 shows an embodiment of the invention corresponding to claim 7. Board 1
The conductive circuit portion 3 formed above and the conductive circuit portion 4 formed on the substrate 2 are anisotropically conductively connected over the entire surface of the facing portion 5. Generally, at the end of such a connection, the burrs of the substrate appear, so even if you try to apply pressure evenly to make the connection, the pressure applied to the end is larger than the pressure applied to other parts. It has been found that, especially in the case of the transparent conductive thin film electrode 4 formed on the flexible substrate 2, cracks may occur and lead to disconnection.

By making the thickness of the substrate requiring connection at the end portion of the connection portion 10% or more thinner than the other portions as in this embodiment, the pressure applied to the end portion can be reduced and the above-mentioned pressure is applied. Could be effectively prevented.

The details of the anisotropic conductive connection portion are as shown in FIG. Here, in the case where anisotropic conductive connection that does not require heating is performed, an ultraviolet curable adhesive such as an acrylic or polyurethane adhesive is used as the dispersion medium 6, and ultraviolet irradiation may be performed simultaneously with pressurization.

It has been found from the above high temperature and high humidity test that the opposing portions of the connecting circuit can substantially block moisture with the anisotropic conductive connecting structure shown in FIG. , Does not expose the conductor portion of only the portion of the conductive circuit portion 3 formed on the circuit board 1 for electrically connecting with an external circuit that does not contribute to anisotropic conductive connection (for example, anisotropic Conductive adhesive may be formed on the entire surface.) The exposed conductor part is subjected to a treatment such as applying a silicone resin, and then subjected to a high temperature and high humidity test (60 ° C., 90% R).
When subjected to H), it was confirmed that there was no deterioration.

Embodiment 8 FIG. 6 shows an embodiment of the invention corresponding to claim 8. Board 1
The conductive circuit portion 3 formed above and the conductive circuit portion 4 formed on the substrate 2 are anisotropically conductively connected over the entire surface of the facing portion 5. Generally, at the end of such a connection, the burrs of the substrate appear, so even if you try to apply pressure evenly to make the connection, the pressure applied to the end is larger than the pressure applied to other parts. It has been found that, especially in the case of the transparent conductive thin film electrode 4 formed on the flexible substrate 2, cracks may occur and lead to disconnection.

At the end of the connecting portion as in this embodiment,
By making the applied pressure smaller by 10% or more in the other portions of the connection, it was possible to effectively prevent the disconnection at the time of pressurization as described above.

The details of the anisotropic conductive connection portion are as shown in FIG. Here, in the case where anisotropic conductive connection that does not require heating is performed, an ultraviolet curable adhesive such as an acrylic or polyurethane adhesive is used as the dispersion medium 6, and ultraviolet irradiation may be performed simultaneously with pressurization.

It has been found from the above-mentioned high temperature and high humidity test that the dispersive medium 6 can substantially shield moisture from the opposing portions of the connecting circuit by adopting the anisotropic conductive connecting structure shown in FIG. , Does not expose the conductor portion of only the portion of the conductive circuit portion 3 formed on the circuit board 1 for electrically connecting with an external circuit that does not contribute to anisotropic conductive connection (for example, anisotropic Conductive adhesive may be formed on the entire surface.) The exposed conductor part is subjected to a treatment such as applying a silicone resin, and then subjected to a high temperature and high humidity test (60 ° C., 90% R).
When subjected to H), it was confirmed that there was no deterioration.

Embodiment 9 FIG. 7 shows an embodiment of the invention corresponding to claim 9. Board 1
The conductive circuit portion 3 formed above and the conductive circuit portion 4 formed on the substrate 2 are anisotropically conductively connected over the entire surface of the facing portion 5. Generally, at the end of such a connection part, burrs of the substrate are exposed, and even if an attempt is made to apply pressure evenly for connection, the pressure applied to the end is less than that applied to other parts. It has been found that the size becomes large, and in particular, in the case of the transparent conductive thin film electrode 4 formed on the flexible substrate 2, cracks may occur and lead to disconnection.

The cross-sectional shape of the pressure head 11 when connecting at the end of the connecting portion as in this embodiment is R-shaped (0.1 R or more) as shown in the drawing, or is tapered (0.1.
1C or more), it is possible to further reduce the pressing force at the end portion of the connection portion at the other portions of the connection portion, and it is possible to effectively prevent the disconnection at the time of pressurization as described above. did it.

The details of the anisotropically conductive connecting portion are as shown in FIG. Here, in the case where anisotropic conductive connection that does not require heating is performed, an ultraviolet curable adhesive such as acrylic or polyurethane is used as the dispersion medium 6, and ultraviolet irradiation may be performed simultaneously with pressurization.

Since it has been found by the above high temperature and high humidity test that the opposing portions of the connecting circuit can substantially shield the moisture by the anisotropic conductive connection structure shown in FIG. , Does not expose the conductor portion of only the portion of the conductive circuit portion 3 formed on the circuit board 1 for electrically connecting with an external circuit that does not contribute to anisotropic conductive connection (for example, anisotropic Conductive adhesive may be formed on the entire surface.) The exposed conductor part is subjected to a treatment such as applying a silicone resin, and then subjected to a high temperature and high humidity test (60 ° C., 90% R).
When subjected to H), it was confirmed that there was no deterioration.

Embodiment 10 FIG. 8 shows an embodiment of the invention corresponding to claim 10. The conductive circuit portion 3 formed on the substrate 1 and the conductive circuit portion 4 formed on the substrate 2 are anisotropically conductively connected to each other over the entire facing portion 5. Generally, at the end of such a connection part, burrs of the substrate are exposed, and even if an attempt is made to apply pressure evenly for connection, the pressure applied to the end is less than that applied to other parts. It has been found that the size becomes large, and in particular, in the case of the transparent conductive thin film electrode 4 formed on the flexible substrate 2, cracks may occur and lead to disconnection.

As shown in the figure, by providing a recess in the pedestal portion which coincides with the end portion of the connecting portion, at the end portion of the connecting portion,
The applied pressure can be made smaller in the other portions of the connection portion, and the disconnection at the time of pressurization as described above can be effectively prevented.

The details of the anisotropic conductive connection portion are as shown in FIG. Here, in the case where anisotropic conductive connection that does not require heating is performed, an ultraviolet curable adhesive such as acrylic or polyurethane is used as the dispersion medium 6, and ultraviolet irradiation may be performed simultaneously with pressurization.

Since it has been found by the above high temperature and high humidity test that the opposing portions of the connecting circuit can substantially shield the moisture by the anisotropic conductive connecting structure shown in FIG. , Does not expose the conductor portion of only the portion of the conductive circuit portion 3 formed on the circuit board 1 for electrically connecting with an external circuit that does not contribute to anisotropic conductive connection (for example, anisotropic Conductive adhesive may be formed on the entire surface.) The exposed conductor part is subjected to a treatment such as applying a silicone resin, and then subjected to a high temperature and high humidity test (60 ° C., 90% R).
When subjected to H), it was confirmed that there was no deterioration.

[0045]

According to the anisotropic conductive connection structure of the first aspect, since the entire surface of the opposing portion of the device side circuit board and the external circuit is adhesively connected, the area of the connection portion is made as narrow as possible, In addition, it is possible to provide a circuit connection structure having excellent moisture resistance reliability. According to the second aspect of the present invention, it is possible to provide a circuit connection structure in which the area of the connection portion is minimized and the moisture resistance is excellent even when a flexible wiring board is used. . According to the invention described in claim 3, in the liquid crystal display device, it is possible to provide a circuit connecting structure in which the area of the connecting portion is made as small as possible and the moisture resistance is excellent. According to the invention described in claim 4, in a liquid crystal display device using a flexible wiring substrate, the area of the connection portion is made as small as possible, and a circuit connection structure having excellent moisture resistance reliability is provided. You can According to the invention described in claims 5 to 7, even when a flexible wiring board is used, the area of the connection portion is made as narrow as possible,
In addition, it is possible to provide a circuit connection structure having excellent connection yield and moisture resistance reliability. According to the invention described in claim 8, there is provided a circuit connecting method in which the area of the connecting portion is made as small as possible and the connecting yield and the moisture resistance reliability are excellent even when a flexible wiring board is used. be able to.
According to the ninth or tenth aspect of the present invention, even when a flexible wiring board is used, the area of the connection portion is made as small as possible, and a circuit connection structure excellent in connection yield and moisture resistance reliability is provided. An enabling connection device can be provided.

[Brief description of drawings]

FIG. 1 is an explanatory view of a first embodiment of an anisotropic conductive connection structure of the present invention, (a) is a plan view and (b) is a sectional view.

FIG. 2 is an explanatory view of a third embodiment of the anisotropic conductive connection structure of the present invention, (a) is a plan view and (b) is a sectional view.

FIG. 3 is an explanatory view of a fifth embodiment of the anisotropic conductive connection structure of the present invention, (a) is a plan view and (b) is a sectional view.

FIG. 4 is an explanatory view of a sixth embodiment of the anisotropic conductive connection structure of the present invention, (a) is a plan view and (b) is a sectional view.

5A and 5B are explanatory views of a seventh embodiment of the anisotropic conductive connection structure of the present invention, FIG. 5A is a plan view and FIG. 5B is a sectional view.

FIG. 6 is a cross-sectional view illustrating the operation of the anisotropic conductive connection system according to the present invention.

FIG. 7 is a cross-sectional view illustrating the principle of operation of the anisotropic conductive connecting device according to the present invention.

FIG. 8 is a cross-sectional view illustrating the principle of operation of the anisotropic conductive connecting device according to the present invention.

9A and 9B are explanatory views of an example of a conventional anisotropic conductive connection structure, in which FIG. 9A is a plan view and FIG. 9B is a sectional view.

FIG. 10 is an enlarged cross-sectional view of the anisotropic conductive connection portion.

[Explanation of symbols]

 1 substrate (external drive circuit substrate) 2 substrate (device side circuit substrate) 3 conductive circuit portion 4 conductive circuit portion 5 facing portion 6 dispersion medium 7 conductive fine particles

Claims (10)

[Claims] 1. An anisotropic conductive connection structure, characterized in that connecting circuit boards, which are formed to face each other and are electrically connected to an external circuit, are adhesively connected to the front surfaces of the facing portions. . 2. The anisotropic conductive connection structure according to claim 1, wherein at least one of the connecting circuit boards formed opposite to each other is a flexible board. 3. One of the pair of circuit boards for connection formed opposite to each other is one side of a pair of substrates forming a liquid crystal display device, and the other circuit board for connection is formed with the other substrate forming the liquid crystal display device. The anisotropic conductive connection structure according to claim 1, wherein the other circuit has a butted structure. 4. The anisotropic conductive connection structure according to claim 3, wherein at least one of the connecting circuit boards formed opposite to each other is a flexible board. 5. A width of an electrode electrically connected to each other at ends of opposing portions of the connecting circuit boards formed to face each other is larger than a width of the other electrodes. 2. The anisotropic conductive connection structure according to 2 or 4. 6. At least one of electrodes electrically connected to each other is divided into a plurality of electrodes at end portions of opposing portions of the connecting circuit boards formed opposite to each other. Item 5. The anisotropic conductive connection structure according to Item 2 or 4. 7. The thickness of at least one substrate at the end portions of the facing portions of the connecting circuit boards formed facing each other is effectively smaller than the thickness of the other portion. Alternatively, the anisotropic conductive connection structure according to item 4. 8. The pressure according to claim 2, 4, 5, 6 or 7, wherein the pressure required for the adhesive connection is substantially smaller at the ends of the facing portions than at the ends of the facing portions. Characteristic anisotropic conductive connection method. 9. The anisotropic conductive connection method according to claim 8, wherein the pressure-bonding surface of the pressure-bonding head for adhesive bonding has a cross-sectional shape of an end portion of an R shape or a taper shape. Anisotropically conductive connection structure. 10. The anisotropic conductive connection method according to claim 8, wherein the pedestal surface facing the crimping head for adhesive connection has a concave cross-sectional shape at a portion corresponding to an end of the adhesive connection portion. An anisotropic conductive connection structure characterized in that.