JP2010208305A - Laminated substrate, display device, manufacturing method of laminated substrate, and manufacturing method of display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated substrate, a display device, a manufacturing method of a laminated substrate and a manufacturing method of a display device, wherein generation of bubbles in an angular part of an adhesive layer can be suppressed even when a double-coated adhesive tape having an adhesive layer without a substrate is used. <P>SOLUTION: The display device is equipped with the first substrate plate, an adhesive layer and the second substrate plate in this order, wherein the first substrate plate and the second substrate plate are adhered with each other by the adhesive layer and the adhesive layer has no substrate and has an angular part formed by roundness chamfer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a bonded substrate, a display device, a method for manufacturing a bonded substrate, and a method for manufacturing a display device. More specifically, a bonded substrate bonded with a double-sided adhesive tape, a display device using the bonded substrate, a method for manufacturing a bonded substrate using a double-sided adhesive tape, and a method for manufacturing a display device using the method About.

Currently, in display devices used for mobile terminal displays such as mobile phones, personal digital assistants (PDAs), and digital cameras, in addition to display panels that display images, the display panels are protected from external impacts, dust, and the like. For this reason, there is known a configuration including a protective plate and a touch panel that enables input on a screen.

The display panel, the protective plate, and the touch panel usually include a substrate made of a rigid body such as glass. However, for example, when the display panel and the touch panel are bonded together, the reflection of light is reduced. In order to improve the visibility of the display device, a configuration is known in which the substrates are bonded together so that a gap such as an air layer does not occur between the substrates. Such a configuration is called an air gapless structure.

In a display device having an air gapless structure, an adhesive resin can be used when the substrates are bonded together, but both sides of the sheet are used from the viewpoint of good workability such as the need for a curing step of the adhesive resin. It has been proposed to use an adhesive tape (see, for example, Patent Document 1).

As a sheet-like double-sided pressure-sensitive adhesive tape, as described in Patent Document 1, a pressure-sensitive adhesive layer is provided on both surfaces of a transparent base film as a base material, and this pressure-sensitive adhesive layer is covered with a release layer. The double-sided pressure-sensitive adhesive tape having such a configuration is excellent in handleability because it has a base material in the pressure-sensitive adhesive layer and is excellent in shape stability.

JP 2005-222266 A

However, double-sided pressure-sensitive adhesive tapes that have a base material in the adhesive layer use PET (polyethylene terephthalate) or the like with a good light transmittance as the base material, but still have a lower light transmittance than when there is no base material. To do. Therefore, there is room for improvement in terms of improving the display quality of the display device.

Therefore, it is conceivable to use a double-sided adhesive tape having an adhesive layer without a base material to bond the entire surface of the substrate. However, since there are minute steps on the surface of the substrate, the adhesive layer is used to absorb this step. It is necessary to increase the thickness. Specifically, the thickness of the pressure-sensitive adhesive layer is required to be about 100 to 200 μm.

Bonding of substrates using a double-sided pressure-sensitive adhesive tape having an adhesive layer with such a thickness is usually performed as follows. First, one peeling layer of the double-sided pressure-sensitive adhesive tape cut out according to the size of the substrate is peeled off, and the pressure-sensitive adhesive layer is attached to the first substrate. Next, the other release layer is peeled off, and the second substrate is attached to the adhesive layer.

Here, the double-sided pressure-sensitive adhesive tape is generally cut out into a rectangular shape because the shape of the substrate is generally rectangular, and the corners of the pressure-sensitive adhesive layer have a right-angle shape. Thus, since the thickness of the adhesive layer is thick, the edge pressure of the cutter for cutting the double-sided adhesive tape is increased at the corners of the adhesive layer, which may cause a minute step.

When such a level difference occurs in the pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive tape, a level difference also occurs at the corner of the pressure-sensitive adhesive layer attached to the first substrate, and bubbles easily remain in the level difference part. Therefore, it is generally performed that the second substrate is attached under a vacuum condition and the remaining bubbles are removed by the subsequent autoclave process.

However, even if the bubbles seem to disappear due to such treatment, the bubbles are minimized and not completely eliminated, so in reliability tests such as a high-temperature storage test performed after bonding the substrates together Bubbles may reappear. Thereby, for example, when a bonded substrate is used for a display device, the reliability and display quality of the display device may be reduced, the product value may be impaired, and the productivity is also reduced. There was room for improvement in these respects.

As the double-sided pressure-sensitive adhesive tape, not only the double-sided pressure-sensitive adhesive tape cut out to the size of the substrate as described above but also a double-sided pressure-sensitive adhesive tape formed in accordance with the size of the substrate can be used. Even if the adhesive layer does not include a base material as described above, the shape stability is poor because the corners are formed at right angles, and when adhered to the first substrate in the same manner as above, Steps are likely to occur at the corners of the adhesive layer, and bubbles may be generated.

The present invention has been made in view of the above situation, and even with a double-sided pressure-sensitive adhesive tape having an adhesive layer without a substrate, a bonded substrate, a display device, and the like that can reduce the generation of bubbles at the corners of the adhesive layer, It is an object of the present invention to provide a method for manufacturing a bonded substrate and a method for manufacturing a display device.

The present inventors have made various studies on a bonded substrate having an air gapless structure using a double-sided pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer having no base material, and bubbles are mainly generated at the corners of the pressure-sensitive adhesive layer. Focusing on this point, it was found that bubbles were generated by minute steps formed at the corners of the adhesive layer. Then, paying attention to the fact that the shape of the corner portion of the adhesive layer is a right angle, and found that the shape of the corner portion of the adhesive layer and the generation of bubbles are related, the adhesive layer of the double-sided adhesive tape is rounded. The thickness of the adhesive layer affixed to the substrate can be made uniform to the corners by eliminating the corners, and the generation of bubbles can be reduced by eliminating the steps at the corners. The inventors have arrived at the present invention by conceiving that the problem can be solved.

That is, the present invention is a bonded substrate provided with a first substrate, an adhesive layer, and a second substrate in this order, and the first substrate and the second substrate are bonded together by the adhesive layer. The pressure-sensitive adhesive layer is a bonded substrate that does not have a base material and has R-chamfered corners.

The first substrate and the second substrate are rigid bodies such as a glass substrate, and both have an air gapless structure in which the entire surface is bonded by an adhesive layer, that is, the entire surface of the substrate is bonded without a gap. The pressure-sensitive adhesive force of the pressure-sensitive adhesive layer is not particularly limited as long as it has such a strength that the substrates can be bonded together, and it is preferable that the pressure-sensitive adhesive layer can be bonded with a slight pressure when bonded to the substrate. It is preferable that the two members can be permanently fixed by being cured by the passage of time or pressure after the heating.

Since the adhesive layer in the present invention does not contain a base material, the adhesive layer is composed only of a material having adhesiveness. The material for forming the adhesive layer is not particularly limited, but an adhesive layer composed only of an acrylic adhesive is preferable in consideration of transparency and adhesiveness. A bonded substrate formed using such an adhesive layer has high transparency and high light transmittance. In addition, a base material here means the support member which has only the function to hold | maintain an adhesion layer, and does not have adhesiveness, specifically, the resin film etc. which were formed with polyester, PET, etc.

In addition, since the adhesive layer has a corner portion that is chamfered, it is difficult for a minute step to be generated at the corner portion of the adhesive layer, and thus the step is less likely to occur when the substrate is attached to the substrate. The generation of bubbles between the substrates can be suppressed. The reason why the pressure-sensitive adhesive layer having the chamfered corner portion is less likely to cause a minute step than the pressure-sensitive adhesive layer having a right-angled corner portion will be described later.

The configuration of the bonded substrate of the present invention is not particularly limited by other components as long as such components are essential.
The preferred form of the bonded substrate in the present invention will be described in detail below.

As a preferable form in the bonded substrate of the present invention, the corner is rounded with a radius of 0.3 mm or more and 0.5 mm or less. Such a form is suitable when the bonded substrate is applied to a display device.

In the display device, the adhesive layer is formed in a size that is smaller than the substrate but larger than the display area in consideration of the bonding tolerance of the substrate. Further, the rounded corners are formed to be outside the display area, that is, the non-display area. This is because if the corner portion with the R chamfer is included in the display region, a portion where the adhesive layer is present in the display region and a portion where the adhesive layer is not present are generated, which affects the display quality. Accordingly, in a general air gapless structure display device, in consideration of the substrate size, if the corner portion of the adhesive layer is chamfered with a radius of 0.3 mm to 0.5 mm, the chamfered corner The substrate can be bonded well without being included in the display area.

As a specific example, when the size of the display area is 100 mm × 200 mm, the adhesive layer is formed to be approximately 101 mm × 201 mm larger than the display area. This is because if the adhesive layer is smaller than the display region and the end of the adhesive layer is in the visible region, the quality on display is significantly reduced. In this invention, the corner | angular part of the adhesion layer which protruded from the display area is rounded off. In the above case, the size of the adhesive layer that protrudes from the display area is 0.5 mm on the left and right and 0.5 mm on the top and bottom, so that the upper limit of the radius to be chamfered is 0.5 mm.

The adhesive layer preferably has a thickness of 100 μm or more, and more preferably 125 μm or more, in order to absorb a surface step on the bonding surface of the substrates. Thereby, even if it is a double-sided adhesive tape which does not have a base material, the level | step difference in the surface of the board | substrate bonded together can be absorbed reliably. However, if the thickness of the adhesive layer becomes too thick, it becomes difficult to ensure flatness because the adhesive layer contains no base material, which makes it difficult to keep the distance between the two substrates bonded together. In order to cause unevenness, the upper limit is preferably about 200 μm.

The present invention is also a display device using the bonded substrate, wherein the first substrate is a display panel or a substrate disposed closer to the display surface than the display panel, and the second substrate is The present invention is also directed to a display device that is a substrate disposed closer to the display surface than the first substrate.

Examples of combinations of substrates in the display device include a combination in which the first substrate is a display panel, the second substrate is a touch panel, the first substrate is a display panel, and the second substrate is a protective plate, Examples include a combination in which the substrate is a touch panel and the second substrate is a protective plate.

The display panel is not particularly limited, and examples thereof include a liquid crystal panel, an organic electroluminescence panel, a plasma display panel, and a field emission display panel. The adhesive layer is preferably formed of a transparent resin such as an acrylic resin in consideration of light transmittance.

The present invention is also a method for manufacturing a bonded substrate in which a first substrate and a second substrate are bonded together via an adhesive layer, wherein the manufacturing method is provided between the first release layer and the second release layer. Using the double-sided pressure-sensitive adhesive tape in which the pressure-sensitive adhesive layer is sandwiched and having no substrate in the pressure-sensitive adhesive layer, the first pressure-sensitive adhesive layer exposed by peeling off the first release layer of the double-sided pressure-sensitive adhesive tape is the first substrate. Including a first bonding step for bonding to the second substrate, and a second bonding step for bonding the adhesive layer exposed by peeling the second release layer to the second substrate. It is also a method for manufacturing a bonded substrate having a corner portion where the adhesive layer is rounded.

The double-sided pressure-sensitive adhesive tape used in the first bonding step is a double-sided pressure-sensitive adhesive tape having a size suitable for the whole surface bonding of the two substrates. Such a double-sided pressure-sensitive adhesive tape may be cut into a desired size using a long double-sided pressure-sensitive adhesive tape, or a double-sided pressure-sensitive adhesive tape having an adhesive layer previously formed according to the size of the substrate. It may be used.

The pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive tape needs to have a corner portion that is chamfered. The corner portion with the R chamfer can be realized by cutting the double-sided pressure-sensitive adhesive tape with an R when the double-sided pressure-sensitive adhesive tape is cut into a desired size.

Here, the double-sided pressure-sensitive adhesive tape used in the present invention is a double-sided pressure-sensitive adhesive tape containing a base material in the pressure-sensitive adhesive layer in order to absorb the surface level difference of the substrates to be bonded, because the base material is not included in the pressure-sensitive adhesive layer. In comparison, the thickness of the adhesive layer is increased. Therefore, when cutting the four corners of the pressure-sensitive adhesive layer at right angles when cutting the double-sided pressure-sensitive adhesive tape, the blade pressure of the blade used at the time of cutting is increased, resulting in steps in the four corners of the pressure-sensitive adhesive layer. In the bonded substrate, bubbles may be generated at the four corners of the adhesive layer. On the other hand, in the present invention, by cutting the corners of the adhesive layer with R, the blade pressure is dispersed and an adhesive layer having a uniform film thickness is obtained even at the corners. Can be eliminated.

The instrument which cut | disconnects a double-sided adhesive tape is not specifically limited, A Thomson blade, a pinnacle blade, etc. can be used.

Moreover, in this invention, you may use the double-sided adhesive tape which has the adhesion layer by which R was attached | subjected to the corner | angular part. The double-sided pressure-sensitive adhesive tape having an adhesive layer having such a shape can be realized by a coating method using a mask or the like. However, even with such a configuration, the film thickness can be increased by adding R to the corner of the thick adhesive layer. A double-sided pressure-sensitive adhesive tape that is uniform and has the above-described effects is obtained.

In the first bonding step, the first release layer of the double-sided pressure-sensitive adhesive tape configured as described above is peeled off, and the exposed adhesive layer is bonded to the first substrate. In laminating the double-sided pressure-sensitive adhesive tape here, the laminating is generally performed while applying pressure using a roller. The attached adhesive layer can be attached with a substantially uniform thickness without causing a minute step at the corner portion of the R chamfer.

In the second bonding step, the adhesive layer exposed by peeling the second release layer is attached to the second substrate. At this time, it is preferable to align the first substrate and the second substrate as accurately as possible, and it is preferable to align them within an error range of 100 μm or less.

In the manufacturing method described above, the adhesive layer of the double-sided adhesive tape is cut out with a uniform thickness in the cutting step, so that even in the subsequent first laminating step, a uniform thickness is ensured so as not to cause a minute step at the corner of the adhesive layer. In this way, an adhesive layer can be formed, and thereby, entrainment of bubbles between the substrates can be suppressed even in the second bonding step. Therefore, it is possible to manufacture a bonded substrate with no bubbles between the substrates with high productivity.

The method for producing a bonded substrate of the present invention is not particularly limited as long as such a process is essential and may or may not include other processes. .
The preferable aspect in the manufacturing method of the bonded substrate board of this invention is demonstrated in detail below.

In a preferred embodiment of the method for producing a bonded substrate of the present invention, the corner is rounded with a radius of 0.3 mm to 0.5 mm. In the present invention, the corner portion may be rounded with a radius of less than 0.3 mm. However, when the corner portion is rounded with a radius of 0.3 mm or more, the uniformity of the adhesive material, particularly the uniformity at the end portions of the four corners. To preferred. Further, the upper limit of the radius to be chamfered is 0.5 mm as described above, and this aspect is suitable when applied to a method for manufacturing a display device.

In the double-sided pressure-sensitive adhesive tape, the thickness of the pressure-sensitive adhesive layer is preferably 100 μm or more. As described above, the thickness of the adhesive layer is preferably 100 μm or more, and more preferably 125 μm or more, from the viewpoint of absorbing the step on the surface of the substrate to be attached. In addition, the upper limit of the thickness of the adhesive layer is preferably about 200 μm from the viewpoint of ensuring the flatness of both substrates bonded together.

Moreover, it is preferable that the said 2nd bonding process is performed on vacuum conditions. Thereby, generation | occurrence | production of the bubble which remain | survives between an adhesion layer and a 1st board | substrate and / or between an adhesion layer and a 2nd board | substrate can be suppressed more reliably. Further, even if the substrate is returned to the atmospheric pressure atmosphere and a reliability test such as a high temperature storage test is performed, the bubbles do not recur. In the present invention, the term “vacuum” refers to a state where the pressure is 100 Pa or less, more preferably 10 to 100 Pa.

When the double-sided pressure-sensitive adhesive tape used in the production method is viewed in plan, the first and second release layers are preferably formed in the same or slightly larger shape as the pressure-sensitive adhesive layer. Thereby, it can hold | maintain, without impairing the adhesiveness etc. of an adhesion layer. In addition, since the first and second release layers are formed larger than the adhesive layer, the adhesive layer can be easily released without causing depressions or chips in the adhesive layer.

The thicknesses of the first and second release layers are not particularly limited, but the thickness is 50 μm or more considering that they can be easily peeled off and can be peeled off so as not to cause dents or chips in the adhesive layer. It is preferable that When the release layer has a certain thickness, deformation such as curling of the release layer hardly occurs, and a double-sided pressure-sensitive adhesive tape with good workability can be obtained. However, if the thickness of the first and second release layers exceeds 200 μm, the peelability is reduced, and when these release layers are peeled off, the adhesive layer is likely to be depressed or chipped. The thickness of the second release layer is more preferably in the range of 50 to 200 μm. The thicknesses of the first and second release layers may be different.

Examples of the material of the first and second release layers include a resin film formed of polypropylene, PET, or the like. The materials of the first and second release layers may be different.

The present invention further relates to a method for manufacturing a display device using the method for manufacturing a bonded substrate according to any one of the above, wherein the first substrate is disposed closer to the display surface than the display panel or the display panel. The second substrate is also a method for manufacturing a display device, which is a substrate disposed closer to the display surface than the first substrate. Examples of such substrate combinations are the same as those described for the bonded substrate.

Since the display device manufactured by the method for manufacturing a bonded substrate according to the present invention can make the thickness of the adhesive layer substantially uniform up to the corner as described above, there is no local step, It is excellent in display quality and reliability without generation of bubbles. Further, since a highly reliable display device can be obtained, productivity can be improved.

The manufacturing method of the display device of the present invention is not particularly limited by other steps as long as each step described in the method for manufacturing a bonded substrate is essential.

According to the bonded substrate of the present invention, the corners of the adhesive layer are rounded so that even if the adhesive layer has no base material, both substrates can be bonded without causing a step in the corners. Thereby, generation | occurrence | production of the bubble between board | substrates can be suppressed. Further, according to the display device of the present invention, by using the bonded substrate of the present invention, no bubble is generated in the adhesive layer, and a highly reliable display device having excellent display characteristics can be obtained. Moreover, according to the manufacturing method of the bonded substrate of this invention, the corner | angular part of an adhesion layer is used in the 1st, 2nd bonding process by using the double-sided adhesive tape which has the adhesion layer by which the corner | angular part was chamfered. Can be eliminated, and the generation of bubbles can be suppressed. Furthermore, according to the method for manufacturing a display device of the present invention, by using the method for manufacturing a bonded substrate of the present invention, it is possible to manufacture a display device excellent in display characteristics without generating bubbles in the adhesive layer. .

It is a flowchart figure which shows the manufacturing process of the bonded substrate board which concerns on Embodiment 1. FIG. It is a plane schematic diagram which shows the double-sided adhesive tape in the process of S1 which concerns on Embodiment 1. FIG. 3 is a schematic cross-sectional view illustrating steps S3 to S5 according to Embodiment 1. FIG. It is the top view which shows the state of the board | substrate after the process of S4 which concerns on Embodiment 1 was performed, an enlarged plan view, and an enlarged perspective view. 1 is an exploded perspective view illustrating a configuration of a display device with a touch sensor according to Embodiment 1. FIG. 1 is a schematic plan view showing a configuration of a double-sided pressure-sensitive adhesive tape according to Example 1. FIG. It is the top view which shows the state which affixed the double-sided adhesive tape which concerns on the comparative example 1 on the board | substrate, an enlarged plan view, and an expansion perspective view.

Embodiments are listed below and will be described in more detail with reference to the drawings. However, the present invention is not limited to these embodiments.

Embodiment 1
In this embodiment, a method for manufacturing a bonded substrate performed using a double-sided pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer without a substrate will be described.

FIG. 1 is a flowchart showing a manufacturing process of a bonded substrate according to the present embodiment. As shown in FIG. 1, the manufacturing process of the bonded substrate board concerning this embodiment is a tape preparation process (step S1), the 1st peeling process (step S2) which peels the 1st peeling layer of a double-sided adhesive tape, Adhesive layer attaching step for attaching an adhesive layer to one substrate (step S3), second peeling step for removing the second release layer (step S4), and substrate bonding for attaching another substrate to the adhesive layer A process (step S5) is provided.

First, in the tape preparation step (S1), a double-sided pressure-sensitive adhesive tape in which R is formed at the four corners of the pressure-sensitive adhesive layer according to this embodiment is prepared. The double-sided pressure-sensitive adhesive tape to be prepared may be cut from the long double-sided pressure-sensitive adhesive tape to the size of the substrate to be pasted, or a double-sided pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer previously formed according to the size of the substrate. There may be. When cutting a long double-sided pressure-sensitive adhesive tape, the tape is cut out and rounded off at the same time. That is, the tape is cut out with the corners of the adhesive layer having Rs.

FIG. 2 is a schematic plan view showing the double-sided pressure-sensitive adhesive tape prepared in the step S1. In FIG. 2, the double-sided adhesive tape 10 includes a first release layer 1, an adhesive layer 2, and a second release layer 3 in this order. The pressure-sensitive adhesive layer 2 has such a size that a whole surface of a pair of substrates to be described later can be bonded, and the thickness thereof is 125 μm. The four corners of the adhesive layer 2 are chamfered. Moreover, the planar shape of the first release layer 1 and the second release layer 3 is larger than that of the pressure-sensitive adhesive layer 2 so that the first release layer 1 and the second release layer 3 can be easily peeled in a peeling step described later.

Next, in the first peeling step (S2), the first peeling layer 1 is peeled from the double-sided pressure-sensitive adhesive tape 10 whose corners are rounded as described above.

FIG. 3 is a schematic cross-sectional view illustrating steps S3 to S5. In the adhesive layer attaching step (S3), as shown in FIG. 3 (a), the double-sided adhesive tape 10 from which the first release layer 1 has been peeled and the substrate 20 are aligned, and for example, using a roller 30, By rotating on the second release layer 3, a pressing load in the direction of the arrow is applied, and the adhesive layer 2 is attached to the substrate 20. Thereby, the substrate in the state shown in FIG. 3B is obtained.

Then, in the second peeling step (S4), the second peeling layer 3 is peeled off as shown in FIG. 3C, and the substrate in the state shown in FIG. 4 is obtained. FIG. 4 is a plan view, an enlarged plan view, and an enlarged perspective view showing a state of the substrate after the step S4 is performed. As shown in FIGS. 4A and 4B, the pressure-sensitive adhesive layer 2 whose corners are chamfered is formed on the main surface of the substrate 20. As shown in FIG. 4C, the pressure-sensitive adhesive layer 2 has a substantially uniform thickness up to the corners, and no minute steps are formed. 4B is an enlarged plan view of a region surrounded by a wavy line in FIG. 4A, and FIG. 4C is an enlarged perspective view of the region.

In the substrate bonding step (S5), the substrate 20 shown in FIG. 3C and the other substrate are carried into a vacuum bonding apparatus and bonded to each other. Thereby, as shown in FIG.3 (d), the bonded substrate 50 by which the board | substrate 20 and the board | substrate 40 were bonded together by the adhesion layer 2 is obtained. Since this bonded substrate 50 has no step at the corners of the adhesive layer 2, it is possible to reduce entrainment of bubbles between the substrates.

Below, a specific example is given and demonstrated about the display apparatus with a touch sensor using the bonding method of the board | substrate which concerns on this embodiment, and its manufacturing method.

Example 1
FIG. 5 is an exploded perspective view illustrating the configuration of the display device with a touch sensor according to the present embodiment. In FIG. 5, the display device 100 includes a cover substrate 110, an adhesive layer 120, a touch panel 130 as a touch sensor, an antireflection film (AR film) 150, a gasket 160, a display panel 170 as a display element, The bezel 180 is provided in this order.

In the display device 100, the substrate bonding method described in the above embodiment includes bonding of the cover substrate 110 and the touch panel 130, bonding of the gasket 160 and the display panel 170, and display panel 170 and the bezel 180. However, here, the bonding of the cover substrate 110 and the touch panel 130 will be described as an example.

The cover substrate 110 is a substrate for protecting the touch panel 130, the display panel 170, and the like from dust and impact, and is made of, for example, a resin plate made of acrylic resin, polycarbonate resin, or the like, or a transparent member such as a glass substrate. In this embodiment, a glass substrate is used to provide a light transmitting portion 112 for allowing an image displayed on the display panel 170 to be observed from the observation surface side, and a black light shielding member 113 is provided around the light transmitting portion 112 for observation. When viewed from the surface side, the driver, wiring, and the like arranged around the display panel 170 can be hidden.

The adhesive layer 120 is formed to be larger than the display area of the touch panel 130, and four corners thereof are rounded.

The touch panel 130 is an input device that operates a device by touching the screen with a finger, a pen, or the like. A flexible printed circuit board 140 for driving the touch panel 130 is connected to the touch panel 130.

As a driving method of the touch panel 130, a capacitive coupling method, a resistance film method, an infrared method, an ultrasonic method, an electromagnetic induction / coupling method, and the like are known. In this embodiment, a glass substrate is used as the cover substrate 110. Therefore, a method other than the resistive film method, specifically, a capacitive coupling method was used. In the case where a plastic substrate having a thickness of about 0.8 mm is used as the cover substrate 110, the driving method of the touch panel 130 can be a resistance film method.

The antireflection film 150 is a member provided for preventing incident light on the display area from being reflected and deteriorating display quality, and a transparent film made of a metal oxide, a fluorine-containing compound, or the like is used. it can. The antireflection film 150 can be formed by sputtering, chemical vapor deposition (CVD), physical vapor deposition (PVD), or other methods such as applying an antireflection film material by dipping or the like. Examples include a method of attaching a reflective film.

The gasket 160 is a member for suppressing damage to the display panel 170 due to contact with the bezel 180 that is a rigid body and for improving adhesion between the bezel 180 and the display panel 170. The bezel 180 is a housing that holds the display panel 170. Although it does not specifically limit as a material of the gasket 160, For example, the cushioning property with respect to an impact is high, and a cheap urethane foam can be used suitably.

As the display panel 170, a liquid crystal panel is used in this embodiment. The liquid crystal panel has a configuration in which a liquid crystal layer is sandwiched between a pair of substrates, and a polarizing plate is provided on a main surface opposite to the liquid crystal layer of both substrates.

In the display device 100 configured as described above, the cover substrate 110 and the touch panel 130 are bonded to each other using the planar double-sided adhesive tape configured in the same manner as in FIG. Is done.

FIG. 6 is a schematic plan view showing the configuration of the double-sided pressure-sensitive adhesive tape used in this example. In FIG. 6, a double-sided pressure-sensitive adhesive tape 200 has the same structure as the double-sided pressure-sensitive adhesive tape 10 described in FIG. 2, and the pressure-sensitive adhesive layer 120 is made of a transparent acrylic pressure-sensitive adhesive material and has a thickness of 100 μm. The four corners are rounded with a radius of 0.3 mm. The first release layer 210 and the second release layer 220 are formed of a release film having a thickness of about 50 μm.

In the double-sided pressure-sensitive adhesive tape 200, the first release layer 210 and the second release layer 220 have the same planar dimensions as the length L, but the second release layer than the width W1 of the first release layer 210. The width W2 of 220 is formed slightly larger. Thereby, the 1st peeling layer 210 and the 2nd peeling layer 220 can be easily peeled in the above-mentioned 1st peeling process (S2) and 2nd peeling process (S4).

A positioning mark 230 is provided on the second release layer 220 of the double-sided pressure-sensitive adhesive tape 200. Thereby, the double-sided adhesive tape 200 and the touch panel 130 can be easily aligned.

In the process of S1, the double-sided pressure-sensitive adhesive tape 200 configured as described above was prepared, and the bonding surface of the double-sided pressure-sensitive adhesive tape 200 on the touch panel 130 was cleaned. Then, in the first peeling step (S2), the first peeling layer 210 was peeled off, and the touch panel 130 and the double-sided pressure-sensitive adhesive tape 200 were accurately aligned using the positioning marks 230.

In the adhesive layer attaching step (S3), the roller head of the roller is touched down to the end of the second release layer 220, and the adhesive layer 120 is touched through the second release layer 220 while rotating the roller head. Crimped to 130. The roller diameter of the roller head was 20 mm (20φ), and the operating conditions were a pressure of 0.2 MPa and a moving speed of 50 mm / s.

A second peeling step (S4) is performed on the touch panel 130 to which the double-sided adhesive tape 200 has been attached as described above, and is carried into the vacuum bonding apparatus together with the cover substrate 110 to perform alignment, and the substrate bonding step ( S5) was performed. Bonding of the cover substrate 110 and the touch panel 130 was performed under a vacuum condition of 10 to 100 Pa.

And after sticking the antireflection film 150 to the touch panel 130, the autoclave process was performed and the bubble remaining between board | substrates was removed. Next, when the adhesive layer 120 was observed using an optical microscope, the adhesive layer 120 had a substantially uniform thickness even at the corners, and no local level difference was generated, and generation of bubbles was not observed. It was.

Then, the gasket 160, the display panel 170, and the bezel 180 were laminated | stacked in this order on the obtained bonded substrate, and the display apparatus 100 shown in FIG. 5 was obtained. A reliability test was performed on the display device 100. The reliability test consists of (a) standing at 65 ° C. in an atmosphere of 90% RH (humidity) for 240 hours, (b) leaving at 70 ° C. in a high temperature atmosphere for 240 hours, and (c) changing the temperature conditions for 1 hour. The test was carried out under the four conditions (a) to (d), in which the thermal cycle test was changed from −30 ° C. to 80 ° C., and (d) left for 240 hours in a low temperature atmosphere at −30 ° C.

In the reliability test, in the display device 100, no bubbles were observed in the adhesive layer 120 under any of the conditions (a) to (d). As a result, it was confirmed that in this example, it is possible to obtain the display device 100 with high productivity with no bubbles, excellent display quality, and high reliability.

Moreover, when the film thickness of the edge part and flat part of the adhesion layer 120 was measured using the optical microscope, the film thickness of an edge part is 188 micrometers, the film thickness of a flat part is 186 micrometers, and film thickness difference (DELTA) T is It was confirmed that there was almost no difference in film thickness at the corners of the adhesive layer 120 on which R was formed. In addition, the edge part of the adhesion layer 120 means the same thing as the edge part 2a of the adhesion layer 2 in FIG.4 (c), and the flat part of the adhesion layer 120 is the flatness of the adhesion layer 2 in FIG.4 (c). The same thing as the part 2b is said.

In order to confirm the influence of the cut shape of the double-sided pressure-sensitive adhesive tape in Example 1, the following comparative experiment was conducted.

Comparative Example 1
In this comparative example, a display device was produced in the same manner as in Example 1 except that the corners of the double-sided pressure-sensitive adhesive tape were cut out so as to be substantially perpendicular.

FIG. 7 is a plan view, an enlarged plan view, and an enlarged perspective view showing a state where the double-sided pressure-sensitive adhesive tape according to Comparative Example 1 is attached to a substrate. In Comparative Example 1, when the double-sided pressure-sensitive adhesive tape was cut out in accordance with the size of the substrate, the corners of the double-sided pressure-sensitive adhesive tape were not rounded, and the corners of the pressure-sensitive adhesive layer had a right-angled shape.

Moreover, when a double-sided adhesive tape is affixed to the touch panel 130 using a roller, in the adhesive layer 70 formed on the main surface of the touch panel 130 shown in FIG. 7A, FIGS. 7B and 7C. As shown in FIG. 4, a minute step was formed at the corner, and the generation of bubbles 80 due to this step was observed. 7B is an enlarged plan view of a region surrounded by a wavy line in FIG. 7A, and FIG. 7C is an enlarged perspective view of the region.

A display device was produced in the same manner as in Example 1 using the touch panel 130 in which abnormal formation occurred at the four corners of the adhesive layer 70 as described above. When the obtained display device was observed with an optical microscope, the generation of bubbles was not observed in the display screen although the corners of the adhesive layer 70 were partially stepped.

However, when a reliability test similar to the above was performed using this display device, a crowd of bubbles was generated in the portion where the step difference of the adhesive layer 70 occurred under any of the conditions (a) to (d). I was seen. In addition, some display devices have bubbles generated up to the active screen area. This is because even if the bubbles 80 at the corners of the adhesive layer 70 seem to disappear due to the autoclave treatment, they actually remain as microbubbles, and the bubbles become larger again under the conditions such as the reliability test. It is thought that.

Moreover, when the film thickness of the edge part 70a and the flat part 70b of the adhesion layer 70 was measured using the optical microscope, the film thickness of the edge part 70a is 194 micrometers, and the film thickness of the flat part 70b is 170 micrometers, The thickness difference ΔT was 24 μm, and it was confirmed that there was a film thickness difference at the corners of the adhesive layer 70 formed at a right angle.

1,210 First release layer 2, 70, 120 Adhesive layer 2a, 70a End 2b, 70b Flat part 3, 220 Second release layer 10, 200 Double-sided adhesive tape 20, 40 Substrate 30 Roller 50 Bonded substrate 80 Bubble 100 Display device 110 Cover substrate 112 Translucent portion 113 Light shielding member 130 Touch panel 140 Flexible printed circuit board 150 Antireflection film 160 Gasket 170 Display panel 180 Bezel L Length W1, W2 Width 230 Positioning mark

Claims (8)

A bonded substrate provided with a first substrate, an adhesive layer and a second substrate in this order,
The first substrate and the second substrate are bonded together by the adhesive layer,
The bonded substrate according to claim 1, wherein the adhesive layer has no base material and has corners that are chamfered. The bonded substrate according to claim 1, wherein the corner is rounded with a radius of 0.3 mm to 0.5 mm. A display device using the bonded substrate according to claim 1 or 2,
The first substrate is a display panel or a substrate disposed closer to the display surface than the display panel, and the second substrate is a substrate disposed closer to the display surface than the first substrate. A display device. A method for manufacturing a bonded substrate in which a first substrate and a second substrate are bonded together via an adhesive layer,
The manufacturing method uses a planar double-sided adhesive tape in which an adhesive layer is sandwiched between a first release layer and a second release layer, and the adhesive layer has no substrate.
A first laminating step of laminating the first peeling layer of the double-sided pressure-sensitive adhesive tape to bond the exposed adhesive layer to the first substrate;
A second bonding step of bonding the adhesive layer exposed by peeling the second release layer to the second substrate,
The method for producing a bonded substrate, wherein the double-sided pressure-sensitive adhesive tape has a corner portion in which the pressure-sensitive adhesive layer is rounded. 5. The method for manufacturing a bonded substrate according to claim 4, wherein the corner is rounded with a radius of 0.3 mm to 0.5 mm. The method for producing a bonded substrate according to claim 4 or 5, wherein the double-sided pressure-sensitive adhesive tape has a thickness of the adhesive layer of 100 µm or more. The method for manufacturing a bonded substrate according to claim 4, wherein at least one of the first bonding step and the second bonding step is performed under vacuum conditions. It is a manufacturing method of the display apparatus using the manufacturing method of the bonded substrate board in any one of Claims 4-7,
The first substrate is a display panel or a substrate disposed closer to the display surface than the display panel,
The method for manufacturing a display device, wherein the second substrate is a substrate disposed closer to the display surface than the first substrate.

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