WO2012172768A1 - Display device - Google Patents

Abstract

A liquid crystal display device (1) is provided with: a TFT substrate (2) comprising a flexible plastic substrate (6), a display element layer (7) formed on the plastic substrate (6) and comprising semiconductor elements, and a first coil (9a) made of a wire formed on the display element layer (7); and a flexible printed substrate (24) arranged to be opposed to the first coil (9a), comprising a second coil (25) which performs inductive coupling to the first coil (9a), and provided around a display area (D) which displays images.

Description

Display device

The present invention relates to a display device such as a liquid crystal display device provided with a plastic substrate.

In recent years, in the display field, display devices using plastic substrates, which have great advantages over glass substrates in terms of flexibility, impact resistance and light weight, have received much attention. This has the potential to create a new display device.

As such a display device, for example, a pair of display device substrates (that is, a thin film transistor (TFT) substrate and a color filter (CF) substrate) disposed opposite to each other is provided between the pair of substrates. There has been proposed a liquid crystal display device having a liquid crystal layer.

In this liquid crystal display device, the TFT substrate includes a flexible plastic substrate formed of polyimide resin or the like, and a display element layer provided on the plastic substrate and having TFTs which are semiconductor elements. The CF substrate includes the above-described plastic substrate and a CF element layer provided on the plastic substrate.

Further, in this liquid crystal display device, a display area for displaying an image composed of a plurality of pixels or the like is defined in an inner portion of the sealing material, and a terminal area (drive circuit area) is defined around the display area. ing.

In this terminal region, a terminal is provided, an integrated circuit board (or driver board) connected to the terminal, and a driving circuit board (supplied to the integrated circuit board) for supplying an external signal ( Flexible printed circuit board).

Here, in general, as a method of electrically connecting a terminal formed in a terminal region and a terminal formed on a circuit board such as the above-described flexible printed circuit board, a thin film transistor substrate and a thin film transistor substrate through an adhesive conductive adhesive layer A configuration in which the circuit board is bonded is adopted.

As this conductive adhesive layer, for example, an insulating thermosetting resin is a main component, and the resin is composed of fine particles (for example, spherical metal particles or spherical resin particles plated with metal). An anisotropic conductive adhesive layer in which conductive particles made of metal fine particles are dispersed is used (see, for example, Patent Document 1).

JP 2009-217284 A

When connecting the terminal formed on the flexible pudding substrate and the terminal formed on the TFT substrate via the anisotropic conductive adhesive layer described in Patent Document 1, the anisotropic conductive adhesive layer is used. In a state heated to a predetermined curing temperature, the anisotropic conductive adhesive layer is pressurized via the flexible printed circuit board, and the anisotropic conductive adhesive layer is heated and melted to electrically connect the terminals. ing.

However, in a display device using a plastic substrate, the terminal formed on the flexible printed circuit board may bite into the flexible plastic substrate when the above-described pressure treatment is performed. Then, since the pressure-bonding force to the anisotropic conductive adhesive layer is dispersed, the pressure-bonding of the conductive particles becomes insufficient, and the terminal formed in the terminal region is cracked, resulting in poor connection. As a result, there has been a problem that a signal transmission failure occurs between the TFT substrate and the circuit substrate.

Accordingly, the present invention has been made in view of the above-described problems, and a display device capable of transmitting a signal between a display device substrate and a circuit substrate without using a conductive adhesive layer. The purpose is to provide.

In order to achieve the above object, a display device of the present invention includes a flexible plastic substrate, a display element layer formed on the plastic substrate, having a semiconductor element, and wiring formed in the display element layer. A display device substrate having one coil, and a circuit substrate having a second coil provided in the periphery of a display region for displaying an image and disposed opposite to the first coil and performing inductive coupling with the first coil. It is characterized by providing.

According to this configuration, unlike the above-described prior art, a display device substrate and a circuit substrate having a plastic substrate by inductive coupling between the first coil and the second coil without using an anisotropic conductive adhesive layer. It is possible to transmit signals between the two. Accordingly, since it becomes possible to prevent a signal transmission failure between the display device substrate and the circuit board due to the use of the anisotropic conductive adhesive, a display including a flexible plastic substrate is provided. It is possible to improve the yield of mounting the circuit board on the device substrate.

In addition, unlike the above-described conventional technology, it is not necessary to use an expensive anisotropic conductive adhesive, so that the cost can be reduced.

Furthermore, since the signal is transmitted in a non-contact manner by inductive coupling between the first and second coils, for example, an impact is generated on the display device substrate or the display device substrate is bent. Even in this case, it is possible to ensure the transmission of signals between the display device substrate and the circuit board.

In the display device of the present invention, the display device substrate and the circuit board may be bonded together via an adhesive layer.

According to this configuration, the circuit board can be provided with a simple configuration, and the second coil can be disposed to face the first coil.

In the display device of the present invention, the circuit board may be a flexible printed board.

According to this configuration, the signal between the display device substrate including the plastic substrate and the flexible printed circuit board is obtained by inductive coupling between the first coil and the second coil without using the anisotropic conductive adhesive layer. Can be transmitted.

In the display device of the present invention, the circuit board may be at least one of a gate driver board and a source driver board.

According to this configuration, the display device substrate, the gate driver substrate, and the source driver substrate including the plastic substrate are formed by inductive coupling between the first coil and the second coil without using the anisotropic conductive adhesive layer. It is possible to transmit a signal to at least one of the two.

The display device of the present invention includes a laminated substrate in which a plurality of display device substrates are laminated, each of the plurality of display device substrates has a third coil formed by wiring, and each of the third coils is , May be arranged opposite to perform inductive coupling.

According to the configuration, even when flexible devices are integrated, without using an anisotropic conductive adhesive, between the semiconductor elements formed in the display element layer by inductive coupling by the third coil. Signal transmission can be performed.

In the display device of the present invention, a plurality of display device substrates may be laminated via other adhesive layers.

According to this configuration, since the plurality of display device substrates are stacked via the adhesive layer, the flexible device can be integrated with a simple configuration.

In the display device of the present invention, the display device substrate may be laminated by providing a plastic substrate on the surface of the display element layer in the laminated substrate.

According to this configuration, there is no need to laminate the display device substrate using the adhesive layer, so that a bonding step using the adhesive layer is not necessary, and the cost can be reduced.

In addition, since a bonding step using an adhesive layer is not necessary, it is possible to prevent air bubbles from being caught in the bonding step and to improve the yield.

Furthermore, for example, when a polyimide resin is applied to form a plastic substrate on the surface of the display element layer, the distance between semiconductor elements in the laminated display device substrate can be easily controlled by controlling the application conditions. It becomes possible to control.

In the display device of the present invention, the semiconductor element may be a TFT element.

Further, the display device of the present invention has an excellent characteristic that it is possible to improve the mounting yield of the circuit board on the display device substrate including a flexible plastic substrate. Accordingly, the present invention further includes another display device substrate disposed opposite to the display device substrate, and a display medium layer provided between the display device substrate and the other display device substrate. It is preferably used for an apparatus. Moreover, this invention is used suitably when a display medium layer is a liquid crystal layer.

According to the present invention, in a display device including a flexible plastic substrate, it is possible to prevent a reduction in connection reliability of the circuit board.

1 is a plan view showing a liquid crystal display device according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view showing the liquid crystal display device according to the first embodiment of the present invention, and is a cross-sectional view taken along the line AA in FIG. FIG. 2 is a cross-sectional view showing the liquid crystal display device according to the first embodiment of the present invention, and is a cross-sectional view taken along the line BB of FIG. 4 is a cross-sectional view showing the liquid crystal display device according to the first embodiment of the present invention, and is a cross-sectional view taken along the line CC of FIG. It is sectional drawing for demonstrating the manufacturing method of the liquid crystal display device which concerns on the 1st Embodiment of this invention. It is sectional drawing for demonstrating the manufacturing method of the liquid crystal display device which concerns on the 1st Embodiment of this invention. It is sectional drawing for demonstrating the manufacturing method of the liquid crystal display device which concerns on the 1st Embodiment of this invention. It is sectional drawing for demonstrating the manufacturing method of the liquid crystal display device which concerns on the 1st Embodiment of this invention. It is sectional drawing for demonstrating the manufacturing method of the liquid crystal display device which concerns on the 1st Embodiment of this invention. It is sectional drawing for demonstrating the manufacturing method of the liquid crystal display device which concerns on the 1st Embodiment of this invention. It is sectional drawing for demonstrating the manufacturing method of the liquid crystal display device which concerns on the 1st Embodiment of this invention. It is sectional drawing for demonstrating the manufacturing method of the liquid crystal display device which concerns on the 1st Embodiment of this invention. It is sectional drawing for demonstrating the manufacturing method of the liquid crystal display device which concerns on the 1st Embodiment of this invention. It is sectional drawing for demonstrating the manufacturing method of the liquid crystal display device which concerns on the 1st Embodiment of this invention. It is sectional drawing for demonstrating the manufacturing method of the liquid crystal display device which concerns on the 1st Embodiment of this invention. It is sectional drawing for demonstrating the manufacturing method of the liquid crystal display device which concerns on the 1st Embodiment of this invention. It is sectional drawing which shows the liquid crystal display device which concerns on the 2nd Embodiment of this invention. It is sectional drawing of the laminated substrate in the display area of the liquid crystal display device which concerns on the 2nd Embodiment of this invention. It is sectional drawing which shows the liquid crystal display device which concerns on the 3rd Embodiment of this invention. It is sectional drawing of the multilayer substrate in the display area of the liquid crystal display device which concerns on the 3rd Embodiment of this invention. It is sectional drawing which shows the modification of the TFT substrate which concerns on embodiment of this invention. It is sectional drawing which shows the modification of the liquid crystal display device which concerns on embodiment of this invention. It is sectional drawing which shows the modification of the display element layer which concerns on embodiment of this invention.

(First embodiment)
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the present embodiment, a liquid crystal display device is exemplified as the display device.

FIG. 1 is a plan view showing a liquid crystal display device according to the first embodiment of the present invention, and FIG. 2 is a cross-sectional view showing the liquid crystal display device according to the first embodiment of the present invention. FIG. FIG. 3 is a cross-sectional view showing the liquid crystal display device according to the first embodiment of the present invention, and is a cross-sectional view taken along the line BB of FIG. FIG. 4 is a cross-sectional view showing the liquid crystal display device according to the first embodiment of the present invention, and is a cross-sectional view taken along the line CC of FIG.

As shown in FIG. 1 and FIG. 2, the liquid crystal display device 1 is opposed to the TFT substrate 2, which is a substrate for a display device in which a plurality of thin film transistors (TFTs) as semiconductor elements are formed, and the TFT substrate 2. And a CF substrate 3 which is another display device substrate.

Further, the liquid crystal display device 1 is sandwiched between a liquid crystal layer 4 which is a display medium layer sandwiched between the TFT substrate 2 and the CF substrate 3, and the TFT substrate 2 and the CF substrate 3. The substrate 2 and the CF substrate 3 are bonded to each other, and a sealing material 5 provided in a frame shape is provided to enclose the liquid crystal layer 4.

The sealing material 5 is formed so as to circulate around the liquid crystal layer 4, and the TFT substrate 2 and the CF substrate 3 are bonded to each other via the sealing material 5.

The TFT substrate 2 and the CF substrate 3 are each formed in a rectangular plate shape. In addition, the liquid crystal display device 1 includes a plurality of photo spacers (not shown) for regulating the thickness of the liquid crystal layer 4 (that is, the cell gap).

The TFT substrate 2 includes a plastic substrate 6 having a film-like flexibility formed from a resin material. As a resin material for forming the plastic substrate 6, for example, an organic material such as polyimide resin, polyparaxylene resin, or acrylic resin can be used.

Further, on the plastic substrate 6 of the TFT substrate 2, a display element layer 7 provided with TFT elements and the like is formed.

Here, the display element layer 7 includes a plurality of gate lines (not shown) extending in parallel with each other on the plastic substrate 6, and a plurality of source lines (not shown) extending in parallel with each other so as to be orthogonal to the gate lines. A TFT element (not shown) which is a semiconductor element provided at each intersection of the gate line and the source line, and a plurality of pixel electrodes (not shown) respectively connected to the TFT elements are provided.

Further, the CF substrate 3 includes a plastic substrate 8 having a film-like flexibility (flexibility) formed of a resin material, like the TFT substrate 2. As the resin material for forming the plastic substrate 8, the same material as the organic material for forming the plastic substrate 6 described above can be used.

Further, a CF element layer 19 is formed on the plastic substrate 8 of the CF substrate 3. Here, the CF element layer 19 is provided between each colored layer and a plurality of colored layers (not shown) colored in red, green, or blue, corresponding to each pixel electrode on the TFT substrate 2. And a color filter including a black matrix (not shown).

The CF element layer 19 includes an overcoat layer (not shown) provided on the color filter, a common electrode (not shown) provided on the overcoat layer, and an alignment film (not shown) provided on the common electrode. (Not shown).

The thickness of the plastic substrates 6 and 8 is preferably 3 to 30 μm. If the thickness is less than 3 μm, sufficient mechanical strength may not be obtained. If the thickness is greater than 30 μm, a plastic substrate may be used when forming the display element layer 7 or the CF element layer 19. This is because the warpages of 6 and 8 become large and a problem may occur in the process.

The liquid crystal layer 4 includes, for example, nematic liquid crystal having electro-optical characteristics.

In the liquid crystal display device 1, as shown in FIGS. 1 and 2, a display area D for image display is defined in an area where the TFT substrate 2 and the CF substrate 3 overlap inside the sealing material 5. Yes. Here, the display area D is configured by arranging a plurality of pixels, which are the minimum unit of an image, in a matrix.

Further, as shown in FIG. 1, the liquid crystal display device 1 is formed in a rectangular shape, and the TFT substrate 2 protrudes from the CF substrate 3 on the upper side thereof, and a drive circuit region T is formed in the protruding region. It is prescribed. The drive circuit region T is provided around the display region D as shown in FIG.

As shown in FIG. 2, in the liquid crystal display device 1 of the present embodiment, a flexible printed circuit board 24 that is a drive circuit board is provided in the drive circuit region T, and an adhesive layer 16 having adhesiveness is provided. Accordingly, the TFT substrate 2 and the flexible printed circuit board 24 are bonded to each other.

Further, as shown in FIG. 1, the liquid crystal display device 1 includes a frame region F provided around the display region D. In the frame region F, a gate driver substrate 23 that is an integrated circuit substrate that drives gate lines in the display region D and a source driver substrate 26 that drives source lines in the display region D are provided.

As shown in FIG. 3, in the liquid crystal display device 1 of the present embodiment, in the frame region F, the TFT substrate 2 and the gate driver substrate 23 are bonded together with an adhesive layer 37 having adhesiveness. It has a configuration.

Similarly, as shown in FIG. 4, in the liquid crystal display device 1 of the present embodiment, in the frame region F, the TFT substrate 2 and the source driver substrate 26 are interposed via the adhesive layer 18 having adhesiveness. It becomes the composition to be pasted together.

The adhesive constituting the adhesive layers 16, 18, and 37 is not particularly limited, and examples of the adhesive include adhesives of various resins such as an epoxy resin, a butyral resin, and an acrylic resin. As the adhesive layers 16, 18, and 37, a thermosetting resin or an ultraviolet curable resin can be used.

Here, in the present embodiment, as shown in FIGS. 1 and 2, in the drive circuit region T of the TFT substrate 2, the wiring 22 (that is, the wiring formed in the display element layer 7) 22 on the TFT substrate 2. And a second coil 25 that is formed by wiring on the flexible printed circuit board 24 and that is disposed opposite the first coil 9a and that performs inductive coupling with the first coil 9a. Yes.

As shown in FIGS. 1 and 3, in the frame region F of the TFT substrate 2, the first coil 9b formed by the wiring 22 on the TFT substrate 2 (that is, the wiring formed in the display element layer 7), 9c is provided, and second coils 26a and 26b that are formed by wiring on the gate driver substrate 23 and are arranged to face the first coils 9b and 9c and perform inductive coupling with the first coils 9b and 9c are provided. It has been.

Further, as shown in FIGS. 1 and 4, in the frame region F of the TFT substrate 2, the first coils 9 d and 9 e made of wirings 22 on the TFT substrate 2 (that is, wirings formed on the display element layer 7) are provided. And second coils 27a and 27b that are formed by wiring on the source driver substrate 26 and are arranged to face the first coils 9d and 9e and inductively couple with the first coils 9d and 9e. Yes.

With such a configuration, unlike the above-described conventional technique, the flexible printed circuit board 24, the gate driver board 23, the source driver board 26, and the TFT board are formed by inductive coupling without using an anisotropic conductive adhesive. Signals can be transmitted to and from the TFT elements provided in 2.

More specifically, first, in the flexible printed circuit 24, signals (gate drivers and source drivers) are transmitted to the second coil 25 serving as a transmission coil via a transmission circuit (not shown) connected to the second coil 25. Is transmitted to the first coil 9a of the TFT substrate 2 that performs inductive coupling with the second coil 25.

Next, the signal input to the first coil 9a formed in the drive circuit region T is transmitted through the first coils 9b and 9d in the frame region F of the TFT substrate 2 to the first coils 9b and 9d that serve as transmission coils. And transmitted to the second coils 26a and 27a that perform inductive coupling.

In the gate driver substrate 23, a gate signal is transmitted to the second coil 26b serving as a transmission coil via a driver circuit (not shown) connected to the second coils 26a and 26b. The two coils 26b are transmitted to the first coil 9c of the TFT substrate 2 that performs inductive coupling.

Similarly, in the source driver board 26, a source signal is transmitted to the second coil 27b serving as a transmission coil via a driver circuit (not shown) connected to the second coils 27a and 27b. The signal is transmitted to the first coil 9e of the TFT substrate 2 that performs inductive coupling with the second coil 27b.

In the liquid crystal display device 1, in each pixel, when the gate signal is sent from the gate driver substrate 23 to the gate electrode of the TFT element through the gate line, and the TFT element is turned on, the source driver substrate 26. A source signal is sent to the source electrode of the TFT element via the source line, and a predetermined charge is written to the pixel electrode via the semiconductor layer and drain electrode of the TFT element.

At this time, a potential difference is generated between each pixel electrode of the TFT substrate 2 and the common electrode of the CF substrate 3, and the liquid crystal layer 4, that is, the liquid crystal capacitance of each pixel and the auxiliary capacitance connected in parallel to the liquid crystal capacitance. A predetermined voltage is applied.

In the liquid crystal display device 1, an image is displayed by adjusting the light transmittance of the liquid crystal layer 4 by changing the alignment state of the liquid crystal layer 4 according to the magnitude of the voltage applied to the liquid crystal layer 4 in each pixel. It has a configuration.

In the present embodiment, with such a configuration, it is possible to prevent a signal transmission failure between the TFT substrate 2 and the circuit board (that is, the flexible printed board 24, the gate driver board 23, and the source driver board 26). Therefore, it becomes possible to improve the yield of mounting the circuit board on the TFT substrate 2 including the film-like flexible plastic substrate 6.

In addition, unlike the above-described conventional technology, it is not necessary to use an expensive anisotropic conductive adhesive, so that the cost can be reduced.

Furthermore, since the signal is transmitted between the coils in a non-contact manner by inductive coupling, even if the TFT substrate 2 is impacted or the TFT substrate 2 is bent and used, the TFT substrate It is possible to ensure signal transmission between the circuit board 2 and the circuit board.

Next, a method for manufacturing a liquid crystal display device according to an embodiment of the present invention will be described. 5 to 16 are cross-sectional views for explaining the method of manufacturing the liquid crystal display device according to the first embodiment of the present invention. The manufacturing method shown below is merely an example, and the liquid crystal display device according to the present invention is not limited to the one manufactured by the method shown below.

<TFT substrate manufacturing process>
First, as shown in FIG. 5, for example, a glass substrate 17 having a thickness of about 0.7 mm is prepared as a support substrate.

Next, as shown in FIG. 5, a film-like flexible plastic substrate 6 formed of, for example, a polyimide resin on a glass substrate 17 is, for example, about 20 μm by spin coating or slit coating. Form with thickness.

Next, on the plastic substrate 6, TFT elements, pixel electrodes, first coils 9a to 9e, etc. are patterned to form the display element layer 7 as shown in FIGS. Next, a polyimide resin is applied to the entire substrate by a printing method, and then a rubbing process is performed to form an alignment film. Next, for example, spherical silica or plastic particles are dispersed over the entire substrate to form spacers.

As described above, the TFT substrate 2 constituting the display region D, the terminal region T, and the frame region F can be manufactured.

<CF substrate manufacturing process>
First, as shown in FIG. 8, for example, a glass substrate 20 having a thickness of about 0.7 mm is prepared as a support substrate. Next, as shown in FIG. 8, a film-like flexible plastic substrate 8 formed of, for example, polyimide resin on a glass substrate 20 is, for example, about 20 μm by spin coating or slit coating. Form with thickness.

Next, a color filter including a colored layer and a black matrix is formed on the plastic substrate 8, and an overcoat layer, a common electrode, and the like are patterned to form a CF element layer 19. Thereafter, a polyimide resin is applied to the entire substrate by a printing method, a rubbing process is performed, and an alignment film is formed, whereby the CF substrate 3 constituting the display region D is manufactured.

The black matrix is made of metal materials such as Ta (tantalum), Cr (chromium), Mo (molybdenum), Ni (nickel), Ti (titanium), Cu (copper), and Al (aluminum), and black pigments such as carbon. Are dispersed or a resin material in which a plurality of colored layers having light transmittance are laminated.

<TFT substrate / CF substrate bonding process>
First, for example, using a dispenser, the sealing material 5 made of ultraviolet curing and thermosetting resin or the like is drawn on the CF substrate 3 in a frame shape.

Next, a liquid crystal material for forming the liquid crystal layer 4 is dropped on a region inside the sealing material 5 in the CF substrate 3 on which the sealing material 5 is drawn.

Further, the CF substrate 3 onto which the liquid crystal material is dropped and the TFT substrate 2 are bonded together under reduced pressure.

Next, the front and back surfaces of the bonded body are pressurized by releasing the bonded body to atmospheric pressure. Next, after irradiating the sealing material 5 sandwiched between the bonded bodies with UV light, the sealing material 5 is cured by heating the bonded body, and as shown in FIG. 9, the TFT substrate 2 and the CF substrate 3 A bonded body in which is bonded is produced.

<Circuit board connection process>
Next, in the terminal region T, the first coil 9a formed on the TFT substrate 2 and the second coil 25 formed on the flexible printed circuit board 24 are guided with the flexible printed circuit board 24 facing down (face down). The first coil 9a and the second coil 25 are arranged to face each other so as to perform sexual coupling. Then, the TFT substrate 2 and the flexible printed circuit board 24 are aligned with the adhesive layer 16 interposed between the TFT substrate 2 and the flexible printed circuit board 24.

Next, as shown in FIG. 10, the second coil 25 formed on the flexible printed circuit board 24 is placed on the adhesive layer 16. Then, in a state where the adhesive layer 16 is heated to a predetermined curing temperature, the adhesive layer 16 is pressed with a predetermined pressure toward the TFT substrate 2 via the flexible printed circuit board 24, whereby the adhesive layer 16 is The first coil 9a and the second coil 25 are provided to face each other through the adhesive layer 16 by heating and melting.

Then, in the terminal region T, the TFT substrate 2 and the flexible printed circuit board 24 are bonded to each other through the adhesive layer 16, and inductive coupling is performed by the first coil 9 a and the second coil 25. 2 and the flexible printed circuit board 24 are electrically connected.

In the frame region F, the first coil 9b, 9c formed on the TFT substrate 2 and the second coil 26a formed on the gate driver substrate 23 with the gate driver substrate 23 facing down (face down), The first coil 9b and the second coil 26a, and the first coil 9c and the second coil 26b are arranged to face each other so that the inductive coupling is performed with the 26b. Then, the TFT substrate 2 and the gate driver substrate 23 are aligned with the adhesive layer 37 interposed between the TFT substrate 2 and the gate driver substrate 23.

Similarly, in the frame region F, the first coil 9d, 9e formed on the TFT substrate 2 and the second coil formed on the source driver substrate 26 with the source driver substrate 26 facing down (face down). The first coil 9d and the second coil 27a, and the first coil 9e and the second coil 27b are arranged to face each other so that the coils 27a and 27b perform inductive coupling. Then, the TFT substrate 2 and the source driver substrate 26 are aligned with the adhesive layer 18 interposed between the TFT substrate 2 and the source driver substrate 26.

Next, as shown in FIGS. 11 and 12, the second coils 26 a and 26 b formed on the gate driver substrate 23 are placed on the adhesive layer 37, and the source driver substrate 26 is placed on the adhesive layer 18. The second coils 27a and 27b formed in the above are placed.

Then, with the adhesive layers 18 and 37 heated to a predetermined curing temperature, the adhesive layers 18 and 37 are moved toward the TFT substrate 2 with a predetermined pressure via the gate driver substrate 23 and the source driver substrate 26. By applying pressure, the adhesive layers 18 and 37 are heated and melted. The first coils 9b to 9e and the second coils 26a, 26b, 27a, and 27b are provided to face each other with the adhesive layers 18 and 37 interposed therebetween.

Then, in the frame region F, the TFT substrate 2, the gate driver substrate 23, and the source driver substrate 26 are bonded to each other via the adhesive layers 18 and 37, and the first coils 9b to 9e and the second coils 26a and 26b. 27a and 27b, inductive coupling is performed, and the TFT substrate 2, the gate driver substrate 23, and the source driver substrate 26 are brought into conduction.

<Glass plate peeling process>
Next, as shown in FIGS. 13 to 15, the glass substrate 17 is peeled off by irradiating laser light (arrows in FIGS. 13 to 15) from the glass substrate 17 side. Here, the removal of the glass substrate 17 may not be peeling by laser light irradiation. For example, the glass substrate 17 may be removed using a polishing and etching apparatus.

Here, in a method of connecting a terminal formed on a circuit board such as a flexible printed circuit board and a terminal formed on a TFT substrate through the above-described conventional anisotropic conductive adhesive layer, glass by laser light irradiation is used. When the substrate is peeled off, stress acts on the boundary portion between the plastic substrate and the glass substrate, and deformation such as warpage or undulation occurs in the plastic substrate.

And when such deformations such as warping and undulation occur, the connection between the terminals due to the conductive particles is released, and as a result, the terminals formed on the flexible printed circuit board and the terminals formed on the TFT circuit board There was a problem that a connection failure occurred between them, and a signal transmission failure occurred.

On the other hand, in this embodiment, signals are transmitted between the circuit board and the TFT substrate 2 by inductive coupling without using an anisotropic conductive adhesive layer. Therefore, even when the glass substrate 17 is peeled off by laser light irradiation, stress acts on the boundary portion between the plastic substrate 6 and the glass substrate 17, and deformation such as warpage or undulation occurs in the plastic substrate 6. Signal transmission can be performed.

Next, as shown in FIG. 16, the glass substrate 20 is peeled off by irradiating laser light (arrows in FIG. 16) from the glass substrate 20 side. Here, the removal of the glass substrate 20 may not be peeling by laser light irradiation, as in the case of the glass substrate 17 described above. For example, the glass substrate 20 may be removed using a polishing and etching apparatus.

Then, a polarizing plate (not shown) and a backlight unit (not shown) are provided to complete the liquid crystal display device 1 shown in FIGS.

In addition, a semiconductor device (electronic circuit) configured by laminating rigid LSI chips and transmitting signals between the LSI chips by inductive coupling using a coil is disclosed (for example, JP-A-2005-228981). Issue gazette).

In such an LSI chip, generally, a semiconductor element and a communication coil are formed on a rigid substrate such as a silicon substrate. When manufacturing the conventional semiconductor device, first, on the silicon substrate. After the semiconductor element and the communication coil are formed, the silicon substrate is mechanically polished on the side opposite to the side where the semiconductor element and the coil are formed, so that the thickness of the silicon substrate is about 50 μm. Next, each LSI chip on which the semiconductor element and the coil are formed is bonded via an adhesive layer, whereby a semiconductor device in which a plurality of LSI chips are stacked is manufactured.

Here, in the semiconductor device using such a rigid substrate, the above-described mechanical polishing process has a problem that the manufacturing process takes a long time and costs are increased.

Also, there was a problem that the silicon substrate thinned by polishing was easily damaged.

In addition, since the silicon substrate thinned by polishing has a property of cleaving, in the bonding process with the adhesive layer, the presence of slight cracks causes the damage to spread over a wide range. There was a problem that the yield decreased and the cost increased.

In general, the inductive coupling strength between the coils decreases in proportion to the square of the distance between the coils. Therefore, in order to reduce power consumption, the thickness of the silicon substrate is reduced and the distance between the coils is shortened. There is a need. However, when the thickness of the silicon substrate is reduced, the handleability of the silicon substrate is reduced, and as described above, the polishing process takes a long time, so the thickness of the silicon substrate cannot be sufficiently reduced. It was difficult to reduce power consumption.

Furthermore, crosstalk may occur due to adjacent coils. In order to suppress the occurrence of this crosstalk, it is necessary to secure a certain distance between the adjacent coils. Here, in general, the point where the crosstalk intensity becomes 0 at the portion where the coils influence each other depends on the distance between the coils performing communication. That is, the smaller the distance between the coils that perform communication, the smaller the distance between adjacent coils, thereby suppressing the occurrence of crosstalk. Therefore, it is considered that the coil installation density depends on the thickness of the silicon substrate (see T. Kuroda, “System LSI: Challenges and Opportunities” IEICE TRANS. ELECTRON., VOL89-C, NO.3 Mar. 2006). As described above, when the thickness of the silicon substrate is reduced, the handleability of the silicon substrate is lowered and the polishing process takes a long time. Therefore, the thickness of the silicon substrate cannot be made sufficiently small, and as a result, it is difficult to suppress the occurrence of crosstalk.

On the other hand, in the present invention, as described above, on the glass substrate 17, for example, when the film-like flexible plastic substrate 6 formed of a polyimide resin is formed by a spin coat method or a slit coat method. The thickness of the plastic substrate 6 can be controlled only by changing the set value of the spin coater or the set value of the slit coater. Further, the plastic substrate 6 having a small thickness (for example, about 20 μm) provided with the display element layer 7 having semiconductor elements and the first coils 9a to 9e is removed by peeling the glass substrate 17 by laser light irradiation. Can be formed. Therefore, unlike the above-described conventional semiconductor device, mechanical polishing of the substrate is not necessary, so that it is possible to prevent the manufacturing process from being lengthened and to suppress an increase in cost.

Further, since the plastic substrate 6 has flexibility, even if the thickness is small, unlike the glass substrate, it is possible to prevent the plastic substrate 6 from being damaged without deteriorating the handleability.

In addition, unlike the silicon substrate thinned by polishing, the plastic substrate 6 does not have the property of cleaving, and therefore the plastic substrate 6 is cracked in the circuit substrate connecting process using the adhesive layers 16, 18, and 37. Even in this case, the damage can be prevented from spreading over a wide range. As a result, it is possible to prevent a decrease in yield of the liquid crystal display device 1 and to suppress an increase in cost.

Further, as described above, even when the thickness of the plastic substrate 6 is reduced, the handling property of the plastic substrate 6 is not deteriorated, and the manufacturing process can be prevented from taking a long time. Can be sufficiently reduced in thickness. As a result, it is possible to reduce power consumption used for inductive coupling between the coils. Further, in order to suppress the occurrence of crosstalk, the distance between coils for communication can be reduced (more specifically, the distance can be reduced to about one-tenth that when a silicon substrate is used). Therefore, the installation density of the coil can be improved.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. FIG. 17 is a cross-sectional view showing a liquid crystal display device according to the second embodiment of the present invention, and FIG. 18 is a cross-sectional view of the multilayer substrate in the display region of the liquid crystal display device according to the second embodiment of the present invention. It is.

In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted. Further, the overall configuration of the liquid crystal display device is the same as that described in the first embodiment, and therefore detailed description thereof is omitted here.

In the liquid crystal display device 40 of this embodiment, as shown in FIG. 17, a laminated substrate 2 a obtained by laminating the TFT substrate 2 with an adhesive layer 21 is used instead of the TFT substrate 2 described above.

As shown in FIG. 18, in each of the two stacked TFT substrates 2, a third coil 9f formed by wiring on the TFT substrate 2 (that is, wiring formed in the display element layer 7); There is a feature in that a third coil 9g is provided opposite to the third coil 9f and inductively coupled with the third coil 9f.

With such a configuration, unlike the above-described conventional technique, signals are transmitted between the TFT elements 11 formed on the display element layer 7 by inductive coupling without using an anisotropic conductive adhesive. Is possible.

That is, in this embodiment, in addition to the effects described in the first embodiment, the TFT substrate 2 on which the TFT element 11 is formed is laminated on the plastic substrate 6, and the flexible device is integrated. Even in this case, signals can be transmitted between the TFT elements 11 formed in the display element layer 7 by inductive coupling without using an anisotropic conductive adhesive.

In addition, as an adhesive agent which comprises the adhesive bond layer 21, the adhesive agent of various resin, such as an epoxy resin, a butyral resin, an acrylic resin, is mentioned like the above-mentioned adhesive bond layers 16, 18, and 37, for example. Moreover, a thermosetting resin or an ultraviolet curable resin can be used.

Further, in the present embodiment, after the glass plate peeling process described in FIG. 13 above, the third coil 9f is attached to the TFT substrate 2 on which the third coil 9g is formed via the adhesive layer 21. The laminated substrate 2a is produced by bonding the formed TFT substrate 2 together.

Further, in the TFT substrate manufacturing process, the third coil 9f is formed through the adhesive layer 21 on the TFT substrate 2 on which the third coil 9g is formed, and the glass substrate 17 which is a support substrate is provided. It is good also as a structure which produces the laminated substrate 2a by bonding the TFT substrate 2, and peels the glass substrate 17 in the subsequent glass plate peeling process.

Thus, in the present embodiment, since the plurality of TFT substrates 2 are stacked via the adhesive layer 21, the flexible device can be integrated with a simple configuration.

(Third embodiment)
Next, a third embodiment of the present invention will be described. FIG. 19 is a cross-sectional view showing a liquid crystal display device according to the third embodiment of the present invention, and FIG. 20 is a cross-sectional view of the multilayer substrate in the display region of the liquid crystal display device according to the third embodiment of the present invention. It is.

In addition, in this embodiment, the same code | symbol is attached | subjected about the component similar to the said 1st, 2nd embodiment, and the description is abbreviate | omitted. Further, the overall configuration of the liquid crystal display device is the same as that described in the first embodiment, and therefore detailed description thereof is omitted here.

In the liquid crystal display device 45 of this embodiment, as shown in FIGS. 19 and 20, the two TFT substrates 2 are directly stacked without using the adhesive layer 21 described in the second embodiment. The feature is that the laminated substrate 2b is used.

Similarly to the second embodiment described above, in each of the two stacked TFT substrates 2, a third formed by wiring on the TFT substrate 2 (that is, wiring formed on the display element layer 7). A coil 9f and a third coil 9g arranged in opposition to the third coil 9f and performing inductive coupling with the third coil 9f are provided.

With such a configuration, unlike the above-described conventional technique, signals are transmitted between the TFT elements 11 formed on the display element layer 7 by inductive coupling without using an anisotropic conductive adhesive. Thus, the same effects as those described in the second embodiment can be obtained.

In the present embodiment, in the above TFT substrate manufacturing process, the third coil 9f is formed, and the TFT substrate 2 provided with the glass substrate 17 as the support substrate is subjected to spin coating or slit coating. For example, a polyimide resin is applied with a thickness of about 20 μm, and then a drying treatment and a curing (annealing treatment) are performed to form a film-like flexible plastic substrate 6 formed of the polyimide resin.

After that, the display element layer 7 on which the TFT element 11 and the third coil 9g are formed is formed on the plastic substrate 6, and the glass substrate 17 is peeled off in the glass plate peeling step, whereby the two TFT substrates 2 are formed. The laminated substrate 2b to be configured is produced.

Therefore, in the present embodiment, unlike the above-described second embodiment, it is not necessary to laminate the TFT substrate 2 using the adhesive layer 21, so that a bonding process using the adhesive layer 21 is not necessary. Since the adhesive layer 21 is not used, the cost can be reduced.

In addition, since the bonding step by the adhesive layer 21 is not necessary, it is possible to prevent air bubbles from being caught in the bonding step, and to improve the yield.

Furthermore, when the polyimide resin is applied to form the plastic substrate 6 on the surface of the display element layer 7, the distance between the TFT elements 11 in the laminated TFT substrate 2 can be easily controlled by controlling the application conditions. It becomes possible to control.

In addition, since the two TFT substrates 2 are directly laminated without bonding, the upper TFT substrate 2 can be laminated using, for example, the alignment mark of the lower TFT substrate 2. become. Accordingly, the communication third coils 9f and 9g can be aligned with accuracy of photolithography, and miniaturization is possible. Furthermore, since it is not necessary to form a through hole for electrical connection, the manufacturing process can be simplified.

Note that the above embodiment may be modified as follows.

As shown in FIG. 21, the display element layers 7 of the two TFT substrates 2 constituting the laminated substrate 2 a in the second embodiment are bonded together by the adhesive layer 21, and two TFTs are formed in the adhesive layer 21. The element 11 and the third coils 9f and 9g may be arranged to face each other.

Further, like the liquid crystal display device 46 shown in FIG. 22, in the drive circuit region T, the TFT substrate 2 is bent and formed on the flexible printed circuit board 24 and the first coil 9a formed on the TFT substrate 2. The second coil 25 may be provided so as to face the first coil 9a and perform inductive coupling with the first coil 9a.

With such a configuration, the drive circuit region T can be narrowed, so that the frame of the liquid crystal display device 46 can be reduced.

Further, as shown in FIG. 23, the driver circuit 50 formed on the gate driver substrate 23 and the source driver substrate 26 described above is formed on the display element layer 7, and between these driver circuit 50 and the TFT element 11. The signal transmission may be performed by inductive coupling of the fourth coils 9h to 9j arranged to face each other so as to perform inductive coupling.

With such a configuration, it is not necessary to provide the gate driver substrate 23 and the source driver substrate 26 in the frame region F, so that the frame region F can be narrowed. As a result, the liquid crystal display device can be narrowed. It becomes possible to plan.

In the case of a transmissive liquid crystal display device including a light source such as a backlight 51, as shown in FIG. 23, the driver circuit 50 is formed in a region overlapping with the TFT element 11 (that is, a region where light L is not transmitted). The

In the second and third embodiments, the two TFT substrates 2 may be stacked. Alternatively, three or more TFT substrates 2 may be stacked to form a stacked substrate.

Moreover, in the said embodiment, although demonstrated taking the TFT element as an example as a semiconductor element, a semiconductor element is not limited to this, For example, it formed with polysilicon, amorphous silicon, indium gallium zinc oxide (IGZO). It may be a transistor, a diode, an organic semiconductor, or the like.

In the present embodiment, the display device related to an LCD (liquid crystal display) is shown. However, the display device can be an organic EL (organic electroluminescence), electrophoresis (electrophoretic), PD (plasma display). Plasma display), PALC (plasma addressed liquid crystal display), inorganic EL (inorganic electroluminescence), FED (field emission display), or SED (surface-conduction electron-emitter display) It may be a display device related to an electric field display.

As described above, the present invention is particularly useful for a display device such as a liquid crystal display device provided with a plastic substrate.

1 Liquid crystal display device 2 TFT substrate (substrate for display device)
2a Multilayer substrate 2b Multilayer substrate 3 CF substrate (Other display device substrate)
4 Liquid crystal layer (display medium layer)
DESCRIPTION OF SYMBOLS 5 Seal material 6 Plastic substrate 7 Display element layer 8 Plastic substrate 9a 1st coil 9b 1st coil 9c 1st coil 9d 1st coil 9e 1st coil 9f 3rd coil 9g 3rd coil 9h 4th coil 9i 4th coil 9j 4th coil 11 TFT element (semiconductor element)
16 Adhesive Layer 18 Adhesive Layer 19 CF Element Layer 20 Glass Substrate 21 Adhesive Layer (Other Adhesive Layer)
22 Wiring 23 Gate driver board (circuit board)
24 Flexible printed circuit boards (circuit boards)
25 second coil 26 source driver board 26a second coil 26b second coil 27a second coil 27b second coil 37 adhesive layer 40 liquid crystal display device 45 liquid crystal display device 46 liquid crystal display device 50 driver circuit 51 backlight D display area F Frame area T Drive circuit area

Claims (10)

A flexible plastic substrate, a display element layer formed on the plastic substrate and having a semiconductor element, and a display device substrate having a first coil made of wiring formed on the display element layer;
A display device comprising: a circuit board provided around a display area for displaying an image, and having a second coil disposed opposite to the first coil and inductively coupled to the first coil. . The display device according to claim 1, wherein the display device substrate and the circuit board are bonded together with an adhesive layer interposed therebetween. The display device according to claim 1, wherein the circuit board is a flexible printed circuit board. The display device according to claim 1, wherein the circuit board is at least one of a gate driver board and a source driver board. A plurality of display device substrates, each of which has a third coil formed by the wiring, and each of the third coils is inductively coupled; 5. The display device according to claim 1, wherein the display devices are arranged so as to face each other. The display device according to claim 5, wherein the plurality of display device substrates are stacked via another adhesive layer. 6. The display device according to claim 5, wherein in the laminated substrate, the display device substrate is laminated by providing the plastic substrate on a surface of the display element layer. 8. The display device according to claim 1, wherein the semiconductor element is a TFT element. Another display device substrate disposed opposite to the display device substrate;
The display device according to any one of claims 1 to 8, further comprising: a display medium layer provided between the display device substrate and the other display device substrate. The display device according to claim 9, wherein the display medium layer is a liquid crystal layer.

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