JP2010039211A - Display device and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain sure connection while achieving downsizing and higher density of a terminal part in a display device and a method for manufacturing the same. <P>SOLUTION: In a display panel 10B having a lower substrate 11 on which a terminal 13b comprising a transparent electrode is formed, a terminal peeling prevention film 17 is provided on the terminal 13b. An aperture part 17a for performing connection by wire bonding and having about 10 μm diameter is formed on the terminal peeling prevention film 17. A portion of the terminal 13b other than the aperture part 17a is covered with the terminal peeling prevention film 17 so as to be fixed to the lower substrate 11. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a display device such as electronic paper and a method for manufacturing the same.

  In the future, it is expected that electronic paper capable of holding a display without supplying power and capable of electrically rewriting display contents will rapidly spread. Electronic paper is required to have an ultra-low power consumption that can be displayed in memory even when the power is turned off, and a display that is gentle on the eyes and not fatigued, and research is being carried out with the aim of realizing a display device that is as thin as paper. Applications of electronic paper include electronic books, electronic newspapers, and electronic posters.

When the electronic paper is required to have flexibility (flexibility), a film substrate made of resin is used. The film substrate includes a terminal area in which terminals for connecting to the drive circuit are arranged, and a display area in which display cells are arranged. Usually, a terminal of a flexible substrate on which a drive circuit is mounted is directly crimped to a terminal on the display panel side.
JP-A-10-10581 Japanese Patent Laid-Open No. 06-73736

  In the future, it is expected that display devices will be further refined, and accordingly, miniaturization and higher density of terminals of the display panel are required.

  However, when the display panel terminals are reduced in size and density, it is difficult to directly press-bond the display panel terminals and the flexible substrate terminals. Therefore, in the display device and the manufacturing method thereof, there is a demand for enabling reliable connection while reducing the size and density of the terminals.

  According to one aspect, a flexible film substrate, a terminal formed on the film substrate by a transparent conductor and connected to a driving circuit, and formed on the film substrate, a signal is transmitted through the terminal. There is provided a display device including a given display cell and a terminal peeling prevention film formed on at least the terminal and having an opening through which a part of the terminal is exposed.

  In the said one viewpoint, a terminal is firmly fixed on a film substrate because the terminal which consists of a transparent conductor is covered with a terminal peeling prevention film. In this case, the terminal and the drive circuit are connected by a bonding wire, for example, through an opening of the terminal peeling prevention film. In this connection step, even if a tensile force acts on the terminal, the terminal is firmly fixed on the film substrate by the terminal peeling prevention film as described above, and therefore, peeling and deformation of the terminal can be suppressed. Therefore, reliable connection can be achieved while reducing the size and density of the terminals.

  Hereinafter, embodiments will be described with reference to the accompanying drawings.

(First embodiment)
FIG. 1 is a block diagram showing a display device (liquid crystal display device) according to the first embodiment. FIG. 2 is a top view showing the display panel of the display device. FIG. 3 is a cross-sectional view taken along line II in FIG.

  As shown in FIG. 1, the display device 50 according to the first embodiment includes a blue display element 50B that generates a blue image, a green display element 50G that generates a green image, and a red that generates a red image. The display element 50R is superposed in this order from the viewer side. A light absorption layer 55 made of a black resin is disposed on the back surface of the red display element 50R.

  The blue display element 50B includes a display panel 10B, a scan electrode driving circuit 51, and a data electrode driving circuit 52. The green display element 50G includes a display panel 10G, a scan electrode drive circuit 51, and a data electrode drive circuit 52, and the red display element 50R includes a display panel 10R, the scan electrode drive circuit 51, and the data electrode drive circuit 52. Yes.

  As shown in FIGS. 2 and 3, the display panel 10 </ b> B has a structure in which a cholesteric liquid crystal 18 is sealed between a lower substrate 11 and an upper substrate 12 that are arranged to face each other. Since the lower substrate 11 and the upper substrate 12 require flexibility, they are formed of a resin film having a thickness of about 0.1 mm. As the resin film, for example, a film such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), or polycarbonate can be used.

  The lower substrate 11 and the upper substrate 12 are bonded together by a sealing material 16 applied along the edge of the display area of the lower substrate 11. In the lower substrate 11, a portion protruding to the outside of the display area (left side in FIG. 2) is a terminal area in which terminals connected to the scan electrode driving circuit 51 are arranged. Further, in the upper substrate 12, a portion protruding outside the display area (upper side in FIG. 2) is a terminal area in which terminals connected to the data electrode driving circuit 52 are arranged.

  In the space between the lower substrate 11 and the upper substrate 12, columns 15 arranged in a matrix are provided. The support column 15 is formed to have a height of about 5 μm. Note that the cell gap (interval between the lower substrate 11 and the upper substrate 12) of the display panel 10B is determined by the height of the support column 15.

  As shown in FIG. 3, a transparent electrode (scanning electrode) 13 is formed on the surface of the lower substrate 11 on the liquid crystal 18 side, and a transparent electrode (data electrode) 14 is formed on the surface of the upper substrate 12 on the liquid crystal 18 side. Is formed. The transparent electrode 13 extends in the X direction in FIG. 2, and a portion in the vicinity of the edge of the substrate 11 outside the sealing material 16 serves as a terminal 13b for connection to an external circuit (drive circuit). Further, the transparent electrode 14 extends in the Y direction in FIG. 2, and a portion near the edge of the substrate 12 outside the sealing material 16 serves as a terminal 14 b. The width and interval of the transparent electrodes 13 and 14 are about 50 to 100 μm. These transparent electrodes 13 and 14 are formed of a transparent conductor such as ITO (Indium-Tin Oxide).

  In the display panel 10B, a portion where the transparent electrodes 13 and 14 intersect is a pixel (display cell). The voltage applied between the transparent electrodes 13 and 14 can change the state of the cholesteric liquid crystal 18 between the transparent electrodes 13 and 14 to a planar state, a focal conic state, or a state in which they are mixed. When the cholesteric liquid crystal 18 is in the planar state, light having a wavelength corresponding to the helical pitch of the liquid crystal molecules (blue in the display panel 10B) is reflected. Further, when the cholesteric liquid crystal 18 is in the focal conic state, the incident light is transmitted. In this manner, a desired image can be displayed by controlling the state of the cholesteric liquid crystal 18 for each pixel.

  In the terminal region of the lower substrate 11, a terminal peeling prevention film 17 that covers the lower substrate 11 and the terminals 13b is formed to a thickness of several μm (for example, about 5 μm). In the present embodiment, it is assumed that the terminal peeling preventing film 17 and the support column 15 are formed of a photosensitive resin.

  The terminal peeling prevention film 17 has an opening 17a for connecting a bonding wire 19 to be described later, and a part of the terminal 13b is exposed through the opening 17a. The opening 17a is formed in a circular shape having a size enough to accommodate the tip of a capillary of a wire bonding apparatus (not shown), for example, a diameter of about several tens of μm. The opening 17a is not limited to a circular shape, and may be a rectangular shape, for example.

  FIG. 4 is a top view showing a state in which the terminal area of the display panel and the flexible substrate are connected.

  As shown in FIG. 4, a plurality of terminals 21 are arranged in one direction (Y direction) on the flexible substrate 20 connected to the lower substrate 11. The wiring extending from the terminal 21 is connected to the scan electrode driving circuit 52. The terminal 21 and the terminal 13b exposed to the opening 17a are connected via a bonding wire 19. As the bonding wire 19, a metal wire such as gold having a diameter of about 25 μm can be used.

  The display panels 10G and 10R have basically the same structure as that of the display panel 10B except that the liquid crystal (helical pitch of liquid crystal molecules) is different. Therefore, the description of the structure of the display panels 10G and 10R is omitted here. .

  Here, FIGS. 5A to 5E are cross-sectional views illustrating the method of manufacturing the display device 50 according to the first embodiment in the order of steps.

  First, as shown in FIG. 5A, a lower substrate 11 and an upper substrate 12 are prepared, and ITO is deposited on the lower substrate 11 and the upper substrate 12 by sputtering to a thickness of about 140 nm. Since the film substrate 11 is made of resin, ITO is deposited by sputtering at a relatively low temperature, for example, about 80 ° C. Subsequently, patterning by a photoresist method is performed to form the transparent electrodes 13 and 14.

  Next, a photosensitive resin is applied on the lower substrate 11 to form a photoresist (photosensitive resin) film, and this photoresist film is exposed and developed, as shown in FIG. A support column 15 is formed in the display area. At the same time, the terminal peeling prevention film 17 covering the terminals 13b is formed on the substrate 11 in the terminal region. However, the terminal peeling prevention film 17 is formed with an opening 17a from which a part of the terminal 13b is exposed.

  Thereafter, the sealing material 16 is applied in a frame shape along the edge of the display area of the lower substrate 11. However, in order to inject liquid crystal between the substrates 11 and 12 in a process to be described later, the sealing material 16 is not applied to a portion that becomes a liquid crystal injection port.

  Next, as shown in FIG. 5C, the lower substrate 11 and the upper substrate 12 are bonded together with a sealing material 16 with the surfaces on which the transparent electrodes 13 and 14 are formed facing each other. Hereinafter, a structure formed by bonding the lower substrate 11 and the upper substrate 12 is referred to as a panel P.

  Next, the panel P is placed in a heat treatment apparatus, and the seal material 16 is cured by heat treatment at a predetermined temperature. Then, after injecting cholesteric liquid crystal 18 into the panel P from a liquid crystal injection port (not shown) by, for example, a vacuum injection method, the liquid crystal injection port is sealed with a resin. As described above, the display panel 10 as shown in FIG. 5C is completed. The display panels 10G and 10R can be manufactured in the same manner except that the injected cholesteric liquid crystal 18 is different.

  Next, as shown in FIG. 5D, the flexible substrate 20 on which the scan electrode driving circuit 51 is mounted is bonded to the terminal region of the lower substrate 11 with an adhesive or the like.

  Next, as illustrated in FIG. 5E, the terminal 13 b of the display panel 10 </ b> B and the terminal 21 of the flexible substrate 20 are connected by the bonding wire 19 using a wire bonding apparatus. Through the above steps, the transparent electrode 13 and the scan electrode drive circuit 51 are electrically connected.

  As described above, the terminal 13b is made of ITO deposited at a low substrate temperature. For this reason, the adhesiveness of the film substrate 11 and the terminal 13b is low, and the terminal 13b is easy to peel off. Therefore, if there is no terminal peeling prevention film 17 in the wire bonding step, as shown in FIGS. 6A and 6B, the terminal 13b is peeled from the lower substrate 11 by a tensile force during wire bonding, There is a risk of significant deformation and cracks and disconnections.

  On the other hand, as shown in FIG. 7, when the terminal 13 b is covered with the terminal peeling prevention film 17, the terminal peeling prevention film 17 is in close contact with the substrate 11 and the terminal 13 b, and the terminal 13 b peels from the substrate 11. Suppress. For this reason, the degree of deformation of the terminal 13b is small, and the occurrence of cracks and disconnection of the terminal 13b can be prevented.

  After the transparent electrode 13 and the scanning electrode driving circuit 51 are wire-bonded, the transparent electrode 14 and a flexible substrate (not shown) on which the data electrode driving circuit 52 is mounted are connected. Thereby, the blue display element 50B is completed. The green display element 50G and the red display element 50R are manufactured in the same manner as the blue display element 50B.

  Next, the blue display element 50B, the green display element 50G, and the red display element 50R are attached in this order from the top, and the light absorption layer 55 is attached to the back surface of the red display element 50R. Thereby, the display device 50 according to the first embodiment is completed.

  As described above, in the display device 50 according to the first embodiment, the terminal 13 b is covered with the terminal peeling prevention film 17. For this reason, even when a tensile force acts on the terminal 13b when connecting the bonding wire 19 to the terminal 13b, damage due to peeling or deformation of the terminal 13b can be suppressed. Therefore, reliable connection can be achieved while reducing the size and density of the terminal 13b.

  Further, since the terminal peeling preventing film 17 is formed at the same time as the support column 15, it can be produced without adding a manufacturing process. Furthermore, since the terminal peeling preventing film 17 is formed by a photoresist method, the opening 17a can be formed with sufficient accuracy for connection by wire bonding.

  In the above example, the terminal peeling prevention film 17 is formed in the terminal region of the lower substrate 11, but the first embodiment is not limited to this, and the terminal region of the upper substrate 12 is not limited thereto. May be provided with the same terminal peeling preventing film 17.

(Second Embodiment)
FIG. 8 is a cross-sectional view illustrating the display panel of the display device according to the second embodiment. FIG. 9 is a cross-sectional view showing the vicinity of the terminal region of the display panel. The display device of the second embodiment is different from the display device of the first embodiment in that the structure of the terminal portion of the display panel is different, and the other structure is basically the same as that of the first embodiment. It is. 8 and FIG. 9, the same components as those in FIG. 3 and FIG.

  As shown in FIG. 8, the display panel 30 has a metal layer 22 formed on the terminals 13b. A terminal peeling prevention film 17 is formed on the metal layer 22. Further, the metal layer 22 is exposed in the opening 17 a of the terminal peeling prevention film 17.

  The metal layer 22 is formed by laminating a metal having a lower electrical resistance than ITO, such as gold, chrome, or copper, on the terminal 13b by sputtering or plating. The thickness of the metal layer 22 is about 50 nm, for example.

  In the second embodiment, the bonding wire 19 is bonded to the metal layer 22 as shown in FIG. For this reason, in 2nd Embodiment, compared with 1st Embodiment, the joining strength of the bonding wire 19 and a terminal improves further, and there exists an effect that the electrical resistance in a junction part becomes small.

  In the first and second embodiments described above, the liquid crystal display device has been described as an example. However, the configuration described in the claims may be applied to an organic EL or other type of display device.

FIG. 1 is a block diagram illustrating a display device according to the first embodiment. FIG. 2 is a top view showing the display panel of the display device according to the first embodiment. FIG. 3 is a cross-sectional view taken along the line II of FIG. FIG. 4 is an enlarged top view showing the vicinity of the terminals of the display panel according to the first embodiment. 5A to 5E are cross-sectional views sequentially showing the manufacturing process of the display device according to the first embodiment. FIG. 6 is a schematic diagram showing a result of connecting terminal regions of the display panel by wire bonding without forming a terminal peeling prevention film. FIG. 7 is a cross-sectional view showing the structure when the display panels are connected by wire bonding. FIG. 8 is a cross-sectional view illustrating the display panel of the display device according to the second embodiment. FIG. 9 is an enlarged cross-sectional view illustrating a terminal region of the display panel of the display device according to the second embodiment.

Explanation of symbols

  10B, 10G, 10R, 30 ... display panel, 11 ... lower substrate, 12 ... upper substrate, 13 ... transparent electrode (scanning electrode), 14 ... transparent electrode (data electrode), 13b, 14b ... terminal, 15 ... column, 16 DESCRIPTION OF SYMBOLS ... Sealing material, 17 ... Terminal peeling prevention film, 17a ... Opening part, 18 ... Cholesteric liquid crystal, 19 ... Bonding wire, 20 ... Flexible substrate, 21 ... Terminal, 22 ... Metal layer, 50 ... Display apparatus, 50B ... Blue display element , 50G ... green display element, 50R ... red display element, 51 ... scan electrode drive circuit, 52 ... data electrode drive circuit, 53 ... scan electrode, 54 ... data electrode, 55 ... light absorption layer.

Claims (6)

A film substrate;
A terminal formed on the film substrate by a transparent conductor and connected to a drive circuit;
A display cell formed on the film substrate and provided with a signal via the terminal;
A terminal peeling prevention film formed on at least the terminal and having an opening from which a part of the terminal is exposed;
A display device comprising: The display cell has a liquid crystal sealed between a counter substrate facing the film substrate and the film substrate,
On the film substrate, there is a support column that maintains a constant distance between the film substrate and the counter substrate,
The display device according to claim 1, wherein the terminal peeling prevention film and the support column are formed of the same resin.   The display device according to claim 1, wherein a layer made of metal is formed between the terminal and the terminal peeling prevention film. And a drive circuit board having terminals electrically connected to the drive circuit;
A bonding wire having one end connected to the terminal of the drive circuit board and the other end connected to the terminal on the film substrate through an opening of the terminal peeling prevention film;
The display device according to claim 1, further comprising: Forming a terminal made of a transparent conductor on the film substrate;
Applying a photosensitive resin on the film substrate;
Exposing and developing the photosensitive resin to form a terminal peeling preventing film having an opening that covers at least the terminal and exposes a part of the terminal; and
A method for manufacturing a display device, comprising: A step of affixing a counter substrate facing the film substrate on the film substrate; and a step of encapsulating liquid crystal between the film substrate and the counter substrate;
The method for manufacturing a display device according to claim 5, wherein in the step of forming the terminal peeling prevention film, a support column is formed at the same time to maintain a constant distance between the film substrate and the counter substrate.

Images