JP2009075556A - Display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that disconnection of a metal wiring layer results by a lapse of time and display failure is generated since corrosion reaction spreading/growing on the metal wiring layer in a connection terminal part of a display device can not perfectly be suppressed. <P>SOLUTION: The display device includes a first substrate having a group of terminal electrodes on one side thereof and a second substrate opposing the first substrate via a liquid crystal material. At least one of the terminal electrodes forms a branched terminal electrode provided with an electrode region spatially branched via an isolation region extending along an elongating direction of each terminal electrode. The second substrate is so disposed as not to cover the terminal electrodes. A corrosion resistant conductive layer covering the terminal electrodes and the isolation region and electrically conducting each terminal electrode isolated by the isolation region is provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a display device, and more particularly to a structure of a connection terminal portion for connecting to an external drive circuit.

  2. Description of the Related Art In recent years, flat display devices (Flat Panel Display Devices) are widely used among display devices as high-resolution displays. A liquid crystal display (LCD), which is one of flat display devices, includes a substrate (hereinafter referred to as a TFT substrate) on which switching elements such as thin film transistors (TFTs) are formed, a color filter, and the like. It has a counter substrate (hereinafter referred to as a CF substrate) on which a black matrix or the like is formed. The liquid crystal display device changes the orientation direction of liquid crystal molecules by changing the electric field applied to the liquid crystal sandwiched between the TFT substrate and the counter substrate, and controls the amount of light transmitted for each pixel. Can be displayed. In order to apply an electric field, the TFT substrate is connected to an external wiring substrate provided with a drive circuit. As this external wiring substrate, TCP (Tape Carrier Package), COG (Chip On Glass), COF (Chip On Film) or the like is used.

  FIG. 10 shows a cross-sectional view of a general liquid crystal display device when TCP is adopted as a wiring board. As shown in FIG. 10, the TFT substrate 1 has a larger area than the CF substrate 13. A region where the TFT substrate 1 and the CF substrate 13 face each other with the liquid crystal material 14 interposed therebetween is called a display region. The region including the region where the TFT substrate 1 protrudes from the CF substrate 13 and the region of the sealing material 15 is disposed adjacent to the display region and is referred to as a peripheral region. Data lines, scanning lines, power supply lines and the like formed in the display area on the TFT substrate 1 are drawn from the display area to the peripheral area to form a terminal electrode group on one side of the substrate. The wiring in the display area, the lead-out wiring, and the terminal electrode are formed in common in the illustrated metal wiring layer 2. The terminal electrode group formed on one end side of the metal wiring layer 2 is electrically connected to the TCP wiring 9 of the TCP 8 through an anisotropic conductive film (hereinafter referred to as ACF) 7. The

  FIG. 11 shows details of the vicinity of the connection portion (hereinafter referred to as a connection terminal portion) between the TFT substrate 1 and the TCP 8 in the peripheral region of FIG. As shown in FIG. 11A and FIG. 11B, the metal wiring layer 2 drawn out to the peripheral region so as to constitute the terminal electrode group is protected by the insulating layer 4. In part, a contact hole 5 for connecting the TFT substrate 1 and the TCP 8 is formed in the insulating layer 4. The contact hole 5 is covered with a surface conductive layer 6 such as ITO (Indium Tin Oxide).

  Thus, the contact hole 5 on the terminal electrode 2 is covered with the surface conductive layer 6 and the ACF 7. However, ITO has a low moisture penetration inhibiting effect, and ACF7 also has a certain level of water absorption. Therefore, it is important to prevent the terminal electrode 2 from corroding and causing display failure due to disconnection or the like.

  Liquid crystal display devices (LCDs) are designed to reduce the resistance of the wiring metal with higher definition and larger screen. For this reason, wiring materials having a low resistance but poor corrosion resistance, such as Al and Cu, have been used more frequently than the wiring materials having corrosion resistance such as Cr that have been used so far. Against this background, countermeasures against corrosion of the terminal electrode 2 described above have become increasingly important.

  An example of a technique for solving such a problem is described in Patent Document 1. The connection electrode of the image display device described in Patent Document 1 has a configuration in which an opening (contact hole) which is on the conductive layer and is not covered with the insulating layer is arranged close to one end of the conductive layer. . With this configuration, it is supposed that the time required for the corrosion reaction occurring in a part of the opening to reach both ends of the conductive layer is lengthened, and the occurrence of disconnection can be suppressed.

JP 2004-205550 A (paragraphs [0029]-[0032], FIG. 1)

  In the configuration of the image display device described in Patent Document 1, since the corrosion reaction that transmits and grows the metal wiring layer cannot be completely suppressed, there is a problem in that a disconnection occurs due to the passage of time and a display defect occurs. there were.

  An object of the present invention is to provide a display device that can prevent complete disconnection of a metal wiring layer even if corrosion of the metal wiring layer occurs.

  A display device according to the present invention includes a first substrate including a terminal electrode group formed on a metal wiring layer drawn out from a display region to the periphery of the substrate, and a second substrate disposed to face the first substrate. In the display device, at least one terminal electrode of the terminal electrode group includes a branched terminal electrode including an electrode region that is spatially branched through a separation region along a direction intersecting with the arrangement direction of the terminal electrode group. It is characterized by forming.

  In addition, according to the display device of the present invention, the first substrate on which the switching element is formed and the second substrate facing the first substrate with the liquid crystal material interposed therebetween, the first substrate is a switching device. A plurality of connection terminals including a display region including an element, a peripheral region adjacent to the display region, a metal wiring layer disposed in the peripheral region and extending from the display region, and a connection region in which a part of the metal wiring layer is opened And at least one of the plurality of connection terminal portions has a portion in which the metal wiring layer is composed of two or more wiring regions, and each wiring region is parallel to a direction in which the metal wiring layer extends. It is continuous in the direction and is separated from each other in the direction intersecting or orthogonal to the extending direction.

  In particular, the display device according to the present invention includes a first substrate having a terminal electrode group on one side and a second substrate disposed to face the first substrate with a liquid crystal material interposed therebetween. At least one terminal electrode of the terminal electrode group on the first substrate has a branched terminal electrode having an electrode region that is spatially branched through a separation region along a direction intersecting the arrangement direction of the terminal electrode group Is forming. The second substrate is disposed so as not to cover the terminal electrode group. Further, a corrosion-resistant conductive layer that covers the terminal electrode and the separation region in common and electrically conducts each terminal electrode isolated by the separation region is provided.

    The display device of the present invention has an effect that it is possible to prevent complete disconnection of the connection terminal portion.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, a liquid crystal display device as a display device according to a first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a cross-sectional view showing the structure of the terminal electrode of the liquid crystal display device according to this embodiment. FIG. 1A shows a configuration in a previous stage of connecting a wiring board such as PCT. The TFT substrate 1 as the first substrate is assumed to be an active matrix substrate in which thin film transistors (TFTs) are arranged in a matrix as switching elements (not shown). A color filter, a black matrix, and the like are formed on the CF substrate 13 as the second substrate. A liquid crystal material 14 is sandwiched between the TFT substrate 1 and the CF substrate and sealed with a sealing material 15. As shown in FIG. 1A, the TFT substrate 1 includes a display area and a peripheral area. The display area is an area where the liquid crystal material 14 exists between the CF substrate 13 facing the TFT, and a TFT (not shown) is formed there. The peripheral region is disposed adjacent to the display region, and includes both the region of the sealing material 15 and the region where the TFT substrate 1 protrudes from the CF substrate 13. In this peripheral region, a metal wiring layer 2 drawn from the display region is formed, and as shown in FIG. 1B, a terminal electrode connected to an external wiring substrate provided with a thin film transistor driving circuit is formed.

  FIG. 1B shows a state in which TCP (Tape Carrier Package) is used as a wiring board and TCP 8 and TFT substrate 1 are connected. A TCP wiring 9 as a wiring terminal formed on the TCP 8 is connected to the terminal electrode 2 of the TFT substrate 1 through an anisotropic conductive film (hereinafter referred to as ACF) 7.

  FIG. 2 shows the structure of the terminal electrode of the TFT substrate 1 in this embodiment. 2A is a plan view, and FIG. 2B is a cross-sectional view taken along the line X-X ′ of FIG. FIG. 2 shows a case where two terminal electrodes are arranged side by side in the peripheral region. Usually, a plurality of terminal electrodes are arranged in parallel at the same pitch in accordance with the number of wires to form a terminal electrode group. is doing. However, in the present embodiment, the number and arrangement of terminal electrodes are not particularly limited.

  As shown in FIG. 2, each terminal electrode 2 on the TFT substrate 1 is formed of two metal wiring regions spaced apart from each other. In this embodiment, a slit is provided as a separation region near the center of each terminal electrode 2. That is, a metal layer removing portion (hereinafter referred to as a slit) 3 from which the metal material constituting the terminal electrode 2 was removed was provided. That is, a terminal electrode having a slit, that is, a branched terminal electrode 2 is formed. Here, when corrosion occurs in a part of the terminal electrode 2 having a slit, the generated corrosion progresses in the terminal electrode 2 with time. However, according to the present embodiment, since the terminal electrode 2 is separated by the slit 3, the progress of corrosion is prevented by the slit 3. Therefore, complete disconnection of the terminal electrode 2 due to corrosion can be prevented.

  It is desirable to form the terminal electrode 2 and the lead-out wiring layer connected to the terminal electrode 2 using a low resistance metal film. As the low resistance metal, aluminum (Al), silver (Ag), copper (Cu), or the like can be used as a main material. Furthermore, in order to improve corrosion resistance, you may use what was alloyed with corrosion-resistant metals, such as neodymium (Nd). Further, the terminal electrode 2 and its lead-out wiring layer can also have a laminated structure of two layers and three layers. In addition, the slit 3 should just be provided in at least 1 terminal electrode, and does not necessarily need to be provided in all the terminal electrodes. Moreover, although the slit 3 is made into the slit of the same width in FIG. 2, the shape of the slit 3 is not specifically limited, A width | variety may be changed and you may make it bend. The same applies to other embodiments described below.

As shown in FIG. 2B, a part of the insulating layer 4 formed on the upper layer of the terminal electrode 2 is removed, and a contact hole 5 is formed. Here, the contact hole 5 is formed in each of the separated terminal electrodes 2. The insulating layer 4 is for protecting the terminal electrode 2 from the outside air. The insulating layer 4 is not particularly limited as long as it is an insulating material, but usually an inorganic insulating film such as SiN _X or SiO ₂ is used. In FIG. 2B, the insulating layer 4 is shown in a single layer structure, but a laminated structure of a plurality of insulating materials may be used.

  A surface conductive layer 6 is formed on the upper surface of the insulating layer 4 so as to completely cover the two contact holes 5 of each terminal electrode 2. In the present embodiment, the surface conductive layer 6 is also formed on the upper layer of the slit 3 to increase the connection area with the ACF 7. As the surface conductive layer 6, an oxide transparent conductive film such as ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide) can be used.

  As shown in FIG. 2A, the slit 3 is formed longer than the contact hole 5 and the surface conductive layer 6 that completely covers it. Then, it is desirable to provide slits 3 extending in the direction in which terminal electrode 2 extends, that is, the vertical direction in FIG. This is because the corrosion of the terminal electrode 2 generated at the end of the contact hole 5 is propagated to the terminal electrode 2 existing in the vertical direction of FIG. This is because disconnection can be prevented. The slit 3 on the lower side of FIG. 2A, that is, on the tip side of the terminal electrode is formed up to the tip of the terminal electrode, as shown in FIG. 2A, and the metal wiring layer 2 forming the terminal electrode is formed. A completely separate structure is desirable. However, if the extension distance is sufficient, the slit 3 may be formed halfway to the tip of the contact terminal electrode, similarly to the slit 3 on the upper side in FIG. As the extension distance at this time, for example, a distance equal to or larger than the lateral width of the metal wiring layer 2 can be used.

  Next, the case where the TCP 8 is pressed against the TFT substrate 1 will be described. In this case, as described below, there is a problem that the terminal electrode 2 is corroded due to a positional shift when the TFT substrate 1 and the TCP 8 are connected, resulting in a display defect.

  FIG. 11 shows a state in which the metal wiring layer 2 forming the terminal electrode on the TFT substrate 1 and the TCP wiring 9 of the TCP 8 are bonded together without misalignment. However, in actuality, as shown in FIGS. 12A and 12B, the positions of the metal wiring layer 2 and the TCP wiring 9 are displaced due to variations in alignment accuracy of the pressure welding apparatus used at the time of TCP pressure welding. The case where it is done arises. With respect to this displacement, the product is usually designed with a certain tolerance, so that it does not become defective in the initial display state. However, after a durability test under a high temperature and high humidity environment, there is a problem that display is poor due to the occurrence of corrosion 10 as shown in FIGS. 13 (a) and 13 (b).

  The location where the corrosion 10 due to the positional deviation described above occurs is generally the end portion of the contact hole 5 that is not covered with the insulating layer 4 of the metal wiring layer 2 and the TCP wiring 9 does not oppose due to the positional deviation. This is the end of the contact hole 5 on the other side. There are two possible causes for the mechanism of this corrosion. The first cause is that water vapor or the like easily penetrates from the external environment to the contact hole 5 because the TCP wiring 9 does not cover the upper part of the contact hole 5. The second cause is that the TCP wiring 9 press-contacted to the adjacent terminal electrode approaches the contact hole 5 due to the positional deviation of the TCP wiring 9. In other words, the proximity of the adjacent TCP wiring 9 causes the terminal electrode 2 to receive a different electric field from the adjacent TCP wiring 9 when a display signal is applied, so that a potential difference is generated.

  Then, as time passes, as shown in FIGS. 13B and 13C, the contact hole on the opposite side travels through the metal wiring layer 2 from the end of the contact hole not covered with the TCP wiring 9. Corrosion 10 grows toward the edge. Further, compared with the metal wiring layer 2 immediately below the contact hole 5, the progress of corrosion is slow, but the corrosion also grows in the metal wiring layer 2 covered with the insulating layer 4.

  Due to the progress of the corrosion, the connection resistance between the surface conductive layer 6 and the metal wiring layer 2 is increased, and further, the disconnection is caused by the growth of the corrosion 10 of the metal wiring layer 2, thereby causing a display defect.

  However, according to the liquid crystal display device according to the present embodiment, complete disconnection of the metal wiring layer 2 due to corrosion is prevented even when a positional shift occurs when the TFT substrate 1 and the TCP 8 are connected as described below. can do.

  FIG. 3 shows the structure of the terminal electrode in a state where the TCP 8 is pressed against the TFT substrate 1 of the liquid crystal display device according to the present embodiment via the ACF 7. This figure shows a form in which the TCP wiring 9 is pressed to the left with respect to the terminal electrode of the TFT substrate 1. The surface conductive layer 6 that is the uppermost layer of the terminal electrode and the TCP wiring 9 are connected via the ACF 7. Due to the anisotropy of the ACF 7, it has conductivity only in the direction orthogonal to the main surface of the substrate 1, so that only the TCP wiring 9 facing one terminal electrode of the TFT substrate 1 is connected. The positional deviation at the time of TCP pressure welding occurs for reasons such as variations in alignment accuracy of the pressure welding device. Since it is difficult to always perform pressure welding without positional deviation when TCP pressure welding, the terminal electrode and the TCP 8 are designed with a certain tolerance. Therefore, display failure does not occur in the initial display state.

  As described above, corrosion occurs when misalignment occurs during TCP pressure welding, and connection failure or disconnection occurs due to the progress of this corrosion reaction. The reason why connection failure and disconnection can be solved by adopting the structure of the terminal electrode of this embodiment will be described below.

  As shown in FIGS. 4A and 4B, first, a metal wiring layer (terminal electrode) is formed at the end of the contact hole 5 (contact hole 5 on the right side of each terminal electrode) not covered with the TCP wiring 9. 2 corrosion 10 occurs. The generated corrosion 10 progresses in the left direction of the figure, that is, toward the end of the contact hole on the opposite side as time passes. Since the portion where the corrosion 10 propagates is the metal wiring layer 2, in the structure in which the metal wiring layer 2 is separated as in the present embodiment, the progress of the corrosion 10 at the separation portion of the metal wiring layer 2, that is, the slit 3. Stops (FIG. 4C). Here, in the metal wiring layer 2 separated into two wiring regions, a defect such as an increase in connection resistance due to the progress of corrosion occurs in the metal wiring layer on one side where the corrosion 10 has occurred. However, since the corrosion 10 has not progressed in the other separated metal wiring layer, the connection resistance does not increase and complete disconnection does not occur.

  When the corrosion 10 progresses and the metal wiring layer 2 on one side is corroded throughout (FIG. 4C), the connection resistance of the corroded metal wiring layer 2 is increased, so that the surface conductive layer 6 And the connection resistance between the metal wiring layer 2 also increases. However, the electrical connection can be sufficiently performed only by the connection with the metal wiring layer 2 on the other side where the corrosion is not propagated. Therefore, there is no display problem as a liquid crystal display device.

  On the other hand, the connection electrode (terminal electrode) according to the related technique described in the background art (Japanese Patent Application Laid-Open No. 2004-205550) has a configuration in which the contact hole is arranged close to one end of the conductive layer. However, this configuration is effective only for positional deviation in one direction during TCP pressure welding. Furthermore, since the contact hole is arranged close to one end of the conductive layer, the area of the contact hole is reduced. For this reason, when corrosion occurs in the metal wiring layer of the contact hole, the corrosion progresses over the entire surface of the contact hole, resulting in poor connection between the surface conductive layer and the metal wiring layer.

  Next, the method for manufacturing the terminal electrode of the liquid crystal display device according to the present embodiment will be explained with reference to FIG. FIG. 5 is a process cross-sectional view showing the structure of the terminal electrode of the TFT substrate of this embodiment.

First, as shown in FIG. 5A, a metal wiring layer 2 is formed on the entire surface of the TFT substrate 1 by using, for example, a sputtering method. A glass substrate can be used for the TFT substrate 1. Alternatively, an insulating film such as SiN _X or SiO ₂ deposited on a glass substrate may be used. For example, a low melting point metal such as Al, Ag, or Cu, an Al—Nd alloy in which a corrosion-resistant metal such as Nd is added to Al, or the like can be used for the terminal electrode formed of the metal wiring layer 2 and its lead wiring. . The thickness of the metal wiring layer 2 is not particularly limited, but is about 200 nm in the present embodiment. Further, the metal wiring layer 2 is not limited to the single layer shown in FIG. The film thickness of each metal wiring layer 2 in this case is not particularly limited. For example, the upper metal wiring layer can be an Mo layer of about 50 nm, and the lower metal wiring layer can be an Al layer of about l200 nm. .

  Next, as shown in FIG. 5B, the metal wiring layer 2 is patterned. A normal photolithography technique can be used for the patterning method. In the present embodiment, a positive resist is formed on the portion where the pattern of the metal wiring layer is left, and then the metal wiring layer 2 is etched away using this resist as a mask. The pattern of the metal wiring layer 2 shown in FIG. 5B is obtained by removing the resist. At the time of this patterning, the slit 3 is provided at a predetermined location of at least one terminal electrode to separate the metal wiring layer 2 into a bifurcated shape. The slit 3 preferably includes a region where the surface conductive layer 6 is formed in a later step and extends in the vertical direction of FIG. For the etching of the metal wiring layer 2, for example, a wet etching method using a mixed acid of phosphoric acid / nitric acid / acetic acid / water can be used. By using this wet etching method, it is possible to taper-etch the laminated film collectively even when a Mo / Al-based laminated wiring layer is employed.

Next, as shown in FIG. 5C, an insulating layer 4 is deposited on the entire surface of the TFT substrate 1 so as to completely cover the patterned metal wiring layer 2. For example, a plasma CVD (Chemical Vapor Deposition) method is used to form the insulating layer 4, and a SiN _X film is formed with a thickness of about 300 nm. The material used for the insulating layer 4 is not limited to the SiN _X film, and an insulator such as a SiO ₂ film can be used. Moreover, it is good also not only as a single layer but as a laminated film.

Next, as shown in FIG. 5D, a contact hole 5 is formed in the insulating layer 4 deposited on the metal wiring layer 2. The contact hole 5 is formed in a portion to be a connection region for connecting to the TCP wiring 9 via the ACF 7. A normal photolithography technique can also be used to form the contact hole 5. In the present embodiment, a positive resist is formed in a region other than the region to be the pattern of the contact hole 5, and the insulating layer 4 is removed by etching using this resist as a mask. Thereafter, the resist is removed to form the contact hole 5 shown in FIG. For the etching of the insulating layer 4, for example, a dry etching method using SF ₆ or CHF ₃ gas or a wet etching method using buffered hydrofluoric acid or the like can be used.

  Next, as shown in FIG. 5E, a surface conductive layer 6 is deposited on the entire surface of the TFT substrate 1. A transparent conductive film such as ITO or IZO can be used for the surface conductive layer 6. The surface conductive layer 6 can be formed by depositing this transparent conductive film by sputtering or the like, for example, with a film thickness of about 100 nm.

  Next, as shown in FIG. 5F, the surface conductive layer 6 is patterned to complete the connection region. A normal photolithography technique can be used for patterning. In the present embodiment, a positive resist is formed on a portion where the pattern of the surface conductive layer 6 is left, and the surface conductive layer 6 is removed by etching using this resist as a mask. In the present embodiment, the surface conductive layer 6 is also formed on the insulating layer 4 formed above the slit 3. By removing the resist, the surface conductive layer 6 shown in FIG. 5F is completed. Here, the surface conductive layer 6 is formed so as to completely cover the contact hole 5. The contact hole 5 and the surface conductive layer 6 form a connection region in pressure contact with the TCP wiring 9 via the ACF 7. As the etching method for the surface conductive layer 6, for example, a wet etching method using aqua regia, which is a mixed acid of hydrochloric acid and nitric acid, can be used.

  As described above, in this embodiment, the metal wiring layer 2 of at least one terminal electrode of the TFT substrate 1 is separated into two or more by the slit 3. If the metal wiring layer 2 and the TCP wiring 9 are misaligned during the TCP pressure welding, the metal wiring layer 2 may be corroded at the end of the contact hole 5 that is not covered by the TCP wiring 9. However, according to the liquid crystal display device according to the present embodiment, since the progress of corrosion can be stopped by the slit 3, the complete disconnection of the metal wiring layer 2 can be prevented and the connectivity of the connection region can be maintained.

  Next, a liquid crystal display device as a display device according to a second embodiment of the present invention will be described with reference to FIG. FIG. 6A is a plan view, and FIG. 6B is a cross-sectional view taken along the line X-X ′ of FIG.

  In the first embodiment described above, the case where the metal wiring layer 2 is separated into two wiring regions has been described. However, the present invention is not limited to this, and the effect of the present invention can be achieved if the metal wiring layer 2 is separated into a plurality of parts. Is obtained. FIG. 6 shows the structure of the connection region when the slits 3 are formed at two locations in each terminal electrode and the metal wiring layer 2 is separated into three wiring regions. Contact holes 5 are respectively formed in the three wiring regions of the metal wiring layer 2.

  According to the structure of the terminal electrode of the present embodiment, even if corrosion occurs at the end of the contact hole that is not covered with the TCP wiring 9 and the corrosion progresses, the progress of the corrosion can be stopped by the first slit 3. it can. Therefore, the electrical connection between the TFT substrate 1 and the TCP 8 can be maintained by two of the three contact holes 5 formed. According to the present embodiment, even when corrosion occurs and progresses, the area of the contact hole in which the connection is maintained is larger than that according to the first embodiment. Therefore, the connection resistance in the connection region can be reduced.

  As shown in FIG. 6A, the slit 3 is formed in the connection region where the contact hole 5 and the surface conductive layer 6 that completely covers the contact hole 5 are formed. As in the case of the first embodiment, it is desirable to provide the slit 3 by extending the connection region from the connection region by an extension distance in the direction in which the terminal electrode 2 extends, that is, the vertical direction in FIG. This is because the corrosion of the metal wiring layer 2 generated at the end of the contact hole 5 propagates to the metal wiring layer 2 existing in the vertical direction in FIG. This is because disconnection due to progress can be prevented. The slit 3 on the lower side of FIG. 6A, that is, on the tip side of the connection region is formed up to the tip of the connection region, as shown in FIG. 6A, and the metal wiring layer 2 is completely separated. Is desirable. However, if the extension distance is sufficient, the slit 3 may be formed halfway to the tip of the connection region, similarly to the slit 3 on the upper side in FIG. As the extension distance at this time, for example, a distance equal to or larger than the lateral width of the metal wiring layer 2 can be used.

  Next, a liquid crystal display device as a display device according to a third embodiment of the present invention will be described with reference to FIG. In the first and second embodiments described above, the metal wiring layer 2 is separated by the slit 3. In contrast, in the present embodiment, the metal wiring layer 2 is formed in a different layer in the stacking direction, thereby separating the metal wiring layer 2.

  FIG. 7 shows the structure of the connection region in a state where the TCP 8 is pressed against the TFT substrate 1 of the liquid crystal display device according to the present embodiment. FIG. 7A is a plan view, and FIG. 7B is a cross-sectional view taken along the line X-X ′ of FIG. As shown in FIG. 7B, the metal wiring layer 2 in each connection region was separated in the stacking direction with respect to the TFT substrate 1, and the first metal wiring layer 2a and the second metal wiring layer 2b were formed in different layers. Here, the first metal wiring layer 2a and the second metal wiring layer 2b correspond to two or more wiring regions.

  In FIG. 7B, the first metal wiring layer 2 a and the second metal wiring layer 2 b in the connection region are connected via the surface conductive layer 6. In addition to this configuration or instead of this configuration, a different layer connection portion 11 may be provided in a region other than the connection region as shown in FIG. In this different layer connecting portion 11, the first metal wiring layer 2 a and the second metal wiring layer 2 b are connected through the surface conductive layer 6. Since the contact hole 12 for electrically connecting each metal wiring layer and the surface conductive layer 6 is formed in the different layer connecting portion 11, it is easily affected by the external environment such as moisture. Therefore, it is desirable to provide the different layer connection portion 11 on the display region side from the region where the sealing material 15 for bonding the TFT substrate 1 and the CF substrate 13 shown in FIG.

  In the present embodiment, the metal wiring layers are connected using the surface conductive layer 6 also in the different layer connection portion 11, but the structure is not limited to this, and the metal wiring layers formed in different layers are directly connected to each other. It is good also as connecting with another conductive layer. In the present embodiment, the metal wiring layer 2 is composed of two layers, but may be three or more layers.

  According to the present embodiment, even when the corrosion occurs in one metal wiring layer due to the occurrence of deviation during TCP pressure welding, the metal wiring layer 2 is separated in the stacking direction. Corrosion does not progress in the metal wiring layer. Therefore, the connection in the connection region can be reliably maintained.

  Next, a liquid crystal display device as a display device according to a fourth embodiment of the present invention will be described with reference to FIG.

  FIG. 8 shows the structure of the connection region in a state where the TCP 8 is pressed against the TFT substrate 1 of the liquid crystal display device according to this embodiment. FIG. 8A is a plan view, and FIG. 8B is a cross-sectional view taken along the line X-X ′ of FIG. In the present embodiment, the pattern of the surface conductive layer 6 is changed from that in the first embodiment shown in FIG. 2, and the surface conductive layer 6 is also separated from the metal wiring layer 2 in the same manner. As shown in FIG. 8, contact holes 5 are formed at two locations corresponding to the branched metal wiring layers 2, and the surface conductive layer 6 is formed separately at each of the two contact holes 5. .

  Here, as described in the first embodiment, the corrosion of the metal wiring layer 2 generated at the end portion of the contact hole propagates through the metal wiring layer 2 with the elapsed time and proceeds to the end portion of the contact hole on the opposite side. Go. On the other hand, the surface conductive layer 6 covering the contact hole 5 also has a slower propagation speed than that in the metal wiring layer 2, but there is a possibility that a corrosion reaction occurs and the corrosion proceeds. However, in the connection region according to the present embodiment, since the surface conductive layer 6 is also formed separately, there is no path through which corrosion propagates. Therefore, the progress of corrosion can be completely prevented.

  The slit 3 is formed in the connection region where the contact hole 5 and the surface conductive layer 6 that completely covers the contact hole 5 are formed. Then, it is desirable that the slits 3 are provided by extending from the connection region by an extension distance in the direction in which the metal wiring layer 2 extends, that is, the vertical direction in FIG. This is because the corrosion of the metal wiring layer 2 generated at the end of the contact hole 5 propagates to the metal wiring layer 2 existing in the vertical direction in FIG. This is because disconnection due to progress can be prevented. Note that the slit 3 on the lower side of FIG. 8A, that is, on the distal end side of the connection region is formed up to the distal end of the connection region, as shown in FIG. 8A, and the metal wiring layer 2 is completely separated. Is desirable. However, if the extension distance is sufficient, the slit 3 may be formed halfway up to the tip of the connection region, similarly to the slit 3 on the upper side in FIG. As the extension distance at this time, for example, a distance equal to or larger than the lateral width of the metal wiring layer 2 can be used.

  Next, a liquid crystal display device as a display device according to a fifth embodiment of the present invention will be described with reference to FIG.

  FIG. 9 shows the structure of the connection region in a state where the TCP 8 is pressed against the TFT substrate 1 of the liquid crystal display device according to this embodiment. FIG. 9A is a plan view, and FIG. 9B is a cross-sectional view taken along line X-X ′ of FIG. In the present embodiment, the contact hole 5 is formed across the metal removal portion 3. That is, one contact hole 5 is formed in common with two wiring regions constituting the branched metal wiring layer 2, and the insulating layer 4 is not formed on the upper surface of the slit 3. Then, the surface conductive layer 6 is formed so as to completely cover the contact hole 5. Therefore, since the contact area between the metal wiring layer 2 and the surface conductive layer 6 is increased, the contact resistance between the metal wiring layer 2 and the surface conductive layer 6 can be further reduced. As described in the fourth embodiment, corrosion may propagate through the surface conductive layer 6. However, the propagation speed of corrosion of the surface conductive layer 6 made of ITO or the like is slower than that of the metal wiring layer 2. Therefore, the probability that corrosion propagates through the surface conductive layer 6 to the other branched metal wiring layer 2 is low, and the connection in the connection region can be sufficiently maintained.

  As described above, in the present embodiment, the insulating layer 4 is not formed on the upper surface of the slit 3. Therefore, corrosion may occur from the end of the slit 3. However, even in this case, this problem can be avoided by configuring at least one or more TCP wirings 9 formed in the TCP 8 in a single region that is not separated into two or more. That is, by configuring the TCP wiring 9 to be composed of one region, the TCP wiring 9 is disposed so as to cover the slit 3, so that corrosion can be prevented from occurring at the end of the slit 3. This is because the TCP wiring 9 can prevent penetration of water vapor or the like that causes corrosion into the slit 3. In this case, as in the case of the above-described embodiment, the region where corrosion occurs is limited to one end portion of the metal wiring layer 2 not covered with the TCP wiring 9, so the progress of corrosion is controlled by the slit 3. Can be blocked.

  Also in this embodiment, the slit 3 is formed in the connection region in which the contact hole 5 and the surface conductive layer 6 that completely covers the contact hole 5 are formed. Then, it is desirable to provide slits 3 extending in the direction in which the metal wiring layer 2 extends, that is, the vertical direction in FIG. This is because the corrosion of the metal wiring layer 2 generated at the end of the contact hole 5 propagates to the metal wiring layer 2 existing in the vertical direction in FIG. This is because disconnection due to progress can be prevented. The slit 3 on the lower side of FIG. 9A, that is, on the distal end side of the connection region is formed up to the distal end of the connection region, as shown in FIG. 9A, so that the metal wiring layer 2 is completely separated. Is desirable. However, if the extension distance is sufficient, the slit 3 may be formed halfway up to the tip of the connection region, similarly to the slit 3 on the upper side in FIG. As the extension distance at this time, for example, a distance equal to or larger than the lateral width of the metal wiring layer 2 can be used.

Next, the manufacturing method of the connection region of the liquid crystal display device according to the present embodiment will be explained. Basically, it is the same as in the first embodiment, but in this embodiment, it is necessary to remove the insulating layer 4 on the slit 3 when forming the contact hole shown in FIG. The point is different. For the etching for forming the contact hole, a dry etching method or an etching method using an etching gas such as SF ₆ or CHF ₃ can be used. In the present embodiment, during the etching for forming the contact hole, the TFT substrate 1 exposed in the slit 3 is also etched, and the lower layer substrate of the metal wiring layer 2 may be side-etched. When side etching occurs, the metal wiring layer 2 has an overhanging structure, the step coverage of the surface conductive layer 6 deteriorates, and moisture in the manufacturing process accumulates, causing deterioration of terminal reliability. Therefore, at the time of etching for forming contact holes in the present embodiment, anisotropic dry etching methods such as RIE (Reactive Ion Etching) method that does not cause side etching to the TFT substrate 1, or the insulating layer 4 and the TFT substrate 1. It is preferable to use an etching method with a high selectivity.

  In the first to fifth embodiments described above, the TFT substrate is used as the first substrate constituting the liquid crystal display device. However, the present invention is not limited to this, and active using other switching elements other than TFTs. The present invention can also be applied when a matrix substrate is used. In each of the above embodiments, the present invention is applied to a liquid crystal display device. However, the present invention is not limited to this, and a display device in which a terminal electrode group of a first substrate and a wiring terminal group of an external wiring substrate are connected. The same applies to the above.

  The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the invention described in the claims, and it is also included within the scope of the present invention. Not too long.

  The present invention can be applied to a display device provided with a connection terminal portion.

The structure of the liquid crystal display device which concerns on the 1st Embodiment of this invention is shown, (a) is sectional drawing before connecting TCP, (b) is sectional drawing which shows the structure which connected TCP. 2A is a plan view showing the structure of a connection terminal portion of the TFT substrate according to the first embodiment of the present invention, and FIG. FIG. 6A is a plan view showing a structure of a connection terminal portion (when a displacement occurs) in a state where a TCP is pressed against the TFT substrate according to the first embodiment of the present invention, and FIG. is there. It is a top view (a) which shows the structure (when position shift and corrosion generate | occur | produced) of the connection terminal part in the state which pressure-contacted TCP with the TFT substrate which concerns on the 1st Embodiment of this invention, (b) is corrosion Is a cross-sectional view taken along the line XX ′ in the case where is partially retained, and (c) is a cross-sectional view taken along the line XX ′ when the corrosion has progressed. It is process sectional drawing (a)-(f) which shows the manufacturing method of the connection terminal part of the TFT substrate which concerns on the 1st Embodiment of this invention. FIG. 6A is a plan view showing a structure of a connection terminal portion (when a displacement occurs) in a state where a TCP is pressed against a TFT substrate according to a second embodiment of the present invention, and FIG. is there. FIG. 7A is a plan view showing a structure of a connection terminal portion in a state in which a TCP is pressed against a TFT substrate according to a third embodiment of the present invention (when misalignment occurs), and FIG. is there. FIG. 7A is a plan view showing a structure of a connection terminal portion (when a displacement occurs) in a state in which a TCP is pressed against a TFT substrate according to a fourth embodiment of the present invention, and FIG. is there. FIG. 7A is a plan view showing a structure of a connection terminal portion in a state where a TCP is pressed against a TFT substrate according to a fifth embodiment of the present invention (when misalignment occurs), and FIG. is there. It is sectional drawing which shows the structure of a related liquid crystal display device. It is the top view (a) and X-X 'sectional drawing (b) which show the structure (when there is no position shift) of the connecting terminal part in the state which pressure-contacted TCP with the TFT substrate of the related liquid crystal display device. It is the top view (a) and X-X 'sectional drawing (b) which show the structure (when position shift arises) of the connection terminal part in the state which pressure-contacted TCP with the TFT substrate of the related liquid crystal display device. It is a top view (a) which shows the structure (when position shift and corrosion generate | occur | produces) of the connection terminal part in the state which pressure-contacted TCP with the TFT substrate of the related liquid crystal display device, (b) is corrosion in part It is XX 'sectional drawing in the case of staying, (c) is XX' sectional drawing in case corrosion progresses.

Explanation of symbols

1 TFT substrate 2 Metal wiring layer (including terminal electrode and lead electrode)
2a 1st metal wiring layer 2b 2nd metal wiring layer 3 Metal layer removal part (slit)
4 Insulating layer 5 Contact hole 6 Surface conductive layer 7 Anisotropic conductive film (ACF)
8 TCP
9 TCP wiring 10 Corrosion 11 Different layer connection part 12 Contact hole 13 CF substrate 14 Liquid crystal material 15 Sealing material

Claims (14)

In a display device having a first substrate including a group of terminal electrodes formed on a metal wiring layer drawn out from the display region to the periphery of the substrate, and a second substrate disposed to face the first substrate,
At least one terminal electrode of the terminal electrode group forms a branched terminal electrode having an electrode region spatially branched through a separation region along a direction intersecting the arrangement direction of the terminal electrode group. A display device. The wiring board further includes an external wiring board having a wiring terminal group connected to the terminal electrode group, and at least a wiring terminal connected to the branch type terminal electrode is in at least one of the branched electrode regions. The display device according to claim 1, comprising a single region facing each other. The said isolation | separation area | region contains the removal part from which the metal material which comprises the said terminal electrode was removed, and the said 2 or more said electrode area | region is comprised by the said removal part as a boundary. Display device. It further has a corrosion-resistant conductive layer that covers the terminal electrode and the separation region in common and electrically connects each terminal electrode isolated by the separation region, and the length of the removal portion is longer than the corrosion-resistant conductive layer. The display device according to claim 3, wherein the display device is long. 5. The display according to claim 1, further comprising an insulating layer that covers the terminal electrode so as to have a contact hole that exposes a part of the at least one terminal electrode. 6. apparatus. The display device according to claim 5, wherein the contact hole is formed for each of the branch type terminal electrodes, and has a surface conductive layer that connects and covers the contact hole. The display device according to claim 5, wherein the contact hole is formed for each of the branch type terminal electrodes, and has a surface conductive layer that covers the contact hole separately. 6. The display device according to claim 5, wherein the contact hole is opened so as to include two or more of the branch type terminal electrodes, and has a surface conductive layer that covers the contact hole. 3. The branching terminal electrode according to claim 1, wherein each of the branch type terminal electrodes is formed in two or more different layers spaced apart in a direction orthogonal to the main surface of the first substrate. Display device. The display device according to claim 9, further comprising an insulating layer covering the terminal electrode so as to have a contact hole exposing a part of the at least one terminal electrode. The display device according to claim 10, wherein the contact hole is formed for each of the branch type terminal electrodes, and has a surface conductive layer that connects and covers the contact hole. The display device according to claim 10, wherein the contact hole is formed for each of the branch type terminal electrodes, and has a surface conductive layer that individually covers the contact hole. 13. The display device according to claim 9, further comprising a different-layer connection portion that is disposed in a region other than the connection terminal portion and electrically connects the two or more wiring regions to each other. . A seal member disposed on an outer periphery of the display region and sealing a liquid crystal material between the first substrate and the second substrate, wherein the different layer connecting portion is located on the inner side of the seal material; The display device according to claim 13, wherein the display device is arranged in a region.

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