JP2010191200A - Display and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that the occurrence of short-circuit between pixel electrodes and between bumps of a driving IC chip due to aggregation of conductive particles for use for connection between a substrate of a display and the driving IC chip increases current consumption and causes poor display and element deterioration. <P>SOLUTION: A projection formed in a patterning process of an insulating film and an electrode metal layer formed on the projection are provided to obtain electric conduction between an electrode metal and driving IC bumps. Since fine conductive particles are not used, the increase in current consumption and poor display are avoided, and the reliability against element deterioration is improved. Furthermore, the material cost is reduced and man-hour of COG step is reduced. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a connection method used for connecting a mounting electrode for connecting a wiring of a TFT array of a liquid crystal display device to the outside and a driver IC for supplying a signal and power to the TFT array. TFT-type liquid crystal display devices that are thin and have low power consumption are electronic devices such as OA devices such as personal computers, portable devices such as electronic notebooks and mobile phones, AV devices such as TVs and audios, and in-vehicle devices such as car navigation systems. Widely used in

  In a liquid crystal display device, a TFT-type liquid crystal display device using a liquid crystal display device having a switching element for selectively driving pixel by pixel as a high-speed response speed display such as high image quality, high definition, wide viewing angle range, and moving image. Are known.

  In a liquid crystal display element constituting a TFT type liquid crystal display device, a gate line arranged in parallel in the y direction on the surface of one substrate of a pair of transparent substrates made of glass arranged opposite to each other with a liquid crystal layer interposed therebetween. (Scanning signal lines) and source lines (data lines) that are insulated from the gate lines and arranged in parallel in the x direction are formed. Each region surrounded by the gate line and the source line becomes a pixel region, and a TFT and a transparent pixel electrode are formed as switching elements in the pixel region. When the scanning signal is supplied to the gate line, the TFT is turned on, and a signal from the source line is supplied to the pixel electrode via the turned-on TFT. Signals are input from the driving IC chip (semiconductor integrated circuit) to these gate lines and source lines. This connection is generally conducted by an anisotropic conductive film in which conductive fine particles are dispersed. The driving IC chip is mounted on the TFT array substrate of the liquid crystal display element by COG connection. In recent years, high-density mounting of liquid crystal display elements has been promoted due to the increase in the number of COG connection terminals and the miniaturization of the driving IC chip as the liquid crystal display device has higher definition.

  FIG. 3 is a diagram for explaining a conventional COG connection, and is a cross-sectional view of a liquid crystal element and a driving IC chip. On the transparent substrate 1, an insulating film 2, a metal wiring 4 for a gate line and a source line, and an electrode metal 5 are formed. A bump 7 for connection is formed on the drive IC chip 8, and the electrode metal 5 and the bump 7 are electrically connected by an anisotropic conductive film in which the thermosetting resin 6 and the conductive fine particles 9 are dispersed.

  FIG. 4 is a diagram for explaining the conventional COG connection process shown in FIG. In FIG. 4 (a), the transparent substrate 1 is made of glass, and a gate wire and a source wire metal wiring 4 made of chromium, molybdenum, and aluminum metal are formed thereon (FIG. 4b). Different metals are usually stacked on the metal wiring 4. Next, an insulating film 2 made of an inorganic film such as silicon oxide or an organic film is formed (FIG. 4c). A connection opening is formed in the insulating film 2 (FIG. 4d). Next, an electrode metal 5 made of ITO is formed (FIG. 4e). 4A to 4E show the manufacturing process of the TFT array substrate.

  Next, connection of the driving IC chip will be described. An anisotropic conductive film in which conductive fine particles 9 are dispersed in a thermosetting resin 6 is attached on the electrode metal 5 (FIG. 4f). The conductive fine particles 9 have a structure in which gold or nickel is formed on the spherical surface of resin particles having a diameter of 2 to 4 μm. Further, the diameter accuracy of the conductive fine particles is controlled such that the dispersion is 0.1 μm or less, and stable electrical conduction can be obtained. The drive IC chip 8 is thermocompression bonded with the bumps 7 of the drive IC chip 8 aligned with the openings of the insulating film, and the bumps 7 are electrically connected to the TFT array substrate by the conductive fine particles 9 (FIG. 4g).

  FIG. 5 is a schematic view of the conventional COG connection state shown in FIG. 3 as viewed from above the TFT array substrate. In the figure, 5 is an electrode metal, 4 is a metal wiring, 10 is an opening for connection, 11 is a bottom surface of the opening for connection, 9 ′ is a conductive fine particle that is not electrically conductive, and 9 is an electrical conductor. Conductive fine particles.

  FIG. 6 shows a cross section taken along line A-A ′ in FIG. 5. Metal wiring 4 is formed on the transparent substrate 1, and the insulating film 2 is formed except for the connection portion with the driving IC chip 8. Further, an electrode metal 5 is formed at a connection portion with the driving IC chip, and a TFT array substrate is formed. A driving IC chip 8 provided with bumps 7 is disposed on the opposite side. In the thermosetting resin 6, conductive fine particles (9 ′ is a conductive fine particle that is not conductive, 9 is a conductive fine particle that is conductive) are dispersed, and the TFT array substrate and the driving IC are dispersed by the conductive fine particles 9. Is connected.

JP-A-2-226610 (FIG. 1) Japanese Patent Laid-Open No. 7-316519 (FIG. 1) JP-A-11-305208 (FIGS. 1 and 29)

  In recent years, high-density mounting of liquid crystal display elements has been promoted due to the increase in the number of COG connection terminals and the miniaturization of the driving IC chip as the liquid crystal display device has higher definition. In order to make the bump pitch of the drive IC chip narrower than the configuration of FIG. 5, a configuration in which the mounting density is increased by forming electrode metal pad electrodes in a staggered pattern is schematically shown in FIG. Here, the pad electrode is a connection portion with the driving IC chip in COG mounting. In the figure, there is shown a state in which a collection (aggregation) 99 of conductive fine particles exists between the electrode metals, thereby causing a short circuit.

  FIG. 8 shows a cross-sectional view along line B-B ′ of FIG. 7. The electrode metals 5 and 5 'are electrically connected due to the aggregation 99 of the conductive fine particles. This causes an increase in current consumption, display failure, and element deterioration. In order to prevent the conductive particles from aggregating, it is necessary to increase the dispersibility in the thermosetting resin. For example, if the number of particles is reduced, the connection resistance between the electrode metal and the driving IC bump is increased, The display quality may be deteriorated or hidden. In addition, when the diameter of the conductive fine particles is reduced to increase the dispersion, there is a problem that the connection resistance is increased.

  Accordingly, an object of the present invention is to provide a liquid crystal display device that eliminates a short circuit caused by aggregation of conductive fine particles, eliminates an increase in current consumption and display failure, and improves reliability of element deterioration. To do.

  A display device according to the present invention includes a substrate on which metal wiring is formed, an insulating film provided on the substrate so that part of the metal wiring is exposed from the opening, and an electrode formed in the opening of the insulating film. It has metal. The opening is provided with a protrusion, and the electrode metal is formed so as to cover the protrusion. When the bump of the IC chip and the electrode metal of the protrusion come into contact, the IC chip is electrically connected to the metal wiring. That is, without using conductive fine particles, the electrode metal layer formed on the protrusions of the opening and the bumps of the IC chip are electrically connected, whereby the IC chip is electrically connected to the substrate. With such a configuration, it is possible to establish electrical continuity between the electrode metal and the drive IC bump without short-circuiting even in high-density mounting.

  At this time, 3 to 12 protrusions were provided per opening. Alternatively, the shape of the protrusion was a cylindrical or hemispherical shape having a diameter of 4 μm to 5 μm.

  Furthermore, the total area of the upper surface of the protrusion provided in the opening was set to a range of 2 to 20% of the bottom area of the opening. Further, an organic film having a thickness of 1 μm to 4 μm was used as the insulating film. This organic film may have a laminated structure of an organic film and an inorganic film.

  According to the liquid crystal display device of the present invention, since no conductive fine particles are used, an increase in current consumption and display failure can be eliminated, and the reliability of element deterioration can be improved. In addition, since the conductive particles are not used, the cost of the material is reduced, and the position accuracy of the process of applying the thermosetting resin tape is also lowered, so the man-hours of the COG process are also reduced.

It is sectional drawing which shows the structure of the display apparatus of this invention typically. It is sectional drawing which shows typically the manufacturing process of the liquid crystal display device of this invention. It is sectional drawing which shows the structure of the conventional liquid crystal display device typically. It is sectional drawing which shows typically the manufacturing process of the conventional liquid crystal display device. It is an overhead view showing the COG connection part of the conventional liquid crystal display device. It is sectional drawing which shows the structure of the conventional liquid crystal display device typically. It is an overhead view showing the COG connection part of the conventional liquid crystal display device. It is sectional drawing which shows the structure of the conventional liquid crystal display device typically. It is an overhead view showing the COG connection part of the liquid crystal display device of this invention. It is sectional drawing which shows typically the structure of the liquid crystal display device of this invention. It is an overhead view showing the COG connection part of the liquid crystal display device of this invention. It is an overhead view showing the COG connection part of the liquid crystal display device of this invention. It is sectional drawing which shows typically the structure of the liquid crystal display device of this invention. It is sectional drawing which shows typically the structure of the liquid crystal display device of this invention.

  The display device of the present invention includes a display element configured using a substrate on which an IC chip is mounted. A metal wiring is formed on the substrate constituting the display element, and an insulating film is formed on the substrate so that a part of the metal wiring is exposed from the opening. An electrode metal is formed in the opening of the insulating film. The opening is provided with a protrusion, and the electrode metal is formed so as to cover the protrusion. When the bump of the IC chip and the electrode metal of the protrusion come into contact with each other, the IC chip and the metal wiring are electrically connected. FIG. 1 schematically shows a cross-sectional state in which an IC chip is mounted on a substrate of a display element. A metal wiring 4 is formed on the substrate 1, and an insulating film 2 is provided on the substrate. The insulating film 2 is provided with an opening so that a part of the metal wiring 4 is exposed, and an electrode metal 5 is formed so as to cover the opening. An electrode metal 5 is also provided on the upper surface of the protrusion 3. A bump 7 for connection is formed on the IC chip 8, the substrate 1 and the IC chip 8 are bonded by the thermosetting resin 6, and the electrode metal 5 and the bump 7 are electrically connected.

  Here, since the protrusion is formed of the same material as the insulating film, it is not necessary to add a protrusion forming step.

  The method for manufacturing a display device of the present invention includes a step of forming a metal wiring on a substrate, a step of forming an insulating film on the substrate so as to cover the metal wiring, and a part of the metal wiring is exposed. Forming an opening in the insulating film and forming a protrusion on the opening; forming an electrode metal on the surface of the opening; and forming the electrode metal on the surface of the protrusion; A step of electrically connecting the IC chip and the metal wiring by aligning a bump of the IC chip in the opening and bringing the electrode metal of the bump into contact with the bump, and the IC chip is mounted A step of manufacturing a display element using the substrate is included. The protrusions are formed at the same time when the insulating film is etched to form the openings.

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

  The liquid crystal display device of this example has a structure in which a protrusion formed by a patterning process of an insulating film and an electrode metal are provided on the surface of the protrusion. That is, the liquid crystal display device of this example includes a TFT substrate on which metal wiring is formed, an insulating film formed on the TFT substrate, an electrode metal for forming an opening formed in the insulating film, and the TFT substrate. And a driving IC that is electrically connected to each other. Further, a projection made of the same material as the insulating film is provided in the opening serving as a connection portion with the driving IC, and this projection is formed by electrode metal. When the electrode metal provided on the protrusion is electrically connected to the bump of the driving IC, the driving IC is electrically connected to the TFT substrate, and the liquid crystal display device of the present invention is configured.

  In this embodiment, manufacturing of an array substrate of a liquid crystal display element used in a liquid crystal display device, particularly a manufacturing process of a mounting portion and COG connection will be described with reference to FIG. On the transparent substrate 1 made of glass shown in FIG. 2A, a metal wiring 4 of a gate line or a source line is formed. The metal wiring is laminated with different metals such as chromium, molybdenum, and aluminum (FIG. 2B). Next, the insulating film 2 is formed on this substrate (FIG. 2C). An opening for connection is formed in the insulating film 2. At this time, the opening is formed by dry etching using a photomask, but the insulating film (protrusion 3) is left in the shape of the protrusion by the pattern of the photomask (FIG. 2D). Next, an electrode metal 5 made of ITO is formed (FIG. 2E). The electrode metal 5 is also formed on the surface of the protrusion 3. 2A to 2E are the manufacturing processes of the electrode pad that is the mounting portion of the TFT array substrate.

  Next, connection with the driving IC chip will be described. A thermosetting resin 6 is stuck on the electrode metal 5 (FIG. 2F). When the driving IC chip 8 is thermocompression bonded, the protrusion 3 is deformed and crushed, and the bump 7 and the protrusion 3 come into contact with each other through the electrode metal 5 and are electrically connected. Then, the TFT array substrate and the driving IC chip 8 are fixed by the thermosetting adhesive 6.

  The protrusion 3 is formed in a column shape on the electrode metal 5. The density was set so that the total area of the upper surface of the protrusion 3 was 2 to 20 percent of the bottom area of the electrode pad, considering the ease of crushing by the bumps 7 when the driving IC chip 8 was pressed. The insulating film 2 is formed by applying an acrylic resin with a spinner and then ultraviolet rays and heating. After film formation, it is a transparent thin film. The thickness of the insulating film 2 is 1 to 4 μm. The electrode metal 5 has a thickness of 0.05 to 0.2 μm. The thermosetting resin 6 has a tape shape and a thickness of 20 μm.

  FIG. 9 is a view of the COG connection described in the first embodiment as viewed from above the TFT array substrate, and shows a case where the bump pitch of the drive IC chip is narrow. In the figure, 5 is an electrode metal, 4 is a metal wiring, 10 is an opening for connection, 11 is a bottom surface of the connection opening, 3 is a protrusion formed by etching an insulating film, and the surface is covered with the electrode metal 5. ing.

  FIG. 10 is a sectional view taken along line C-C ′ in FIG. 9. A metal wiring 4 is formed on the transparent substrate 1, a protrusion 3 is formed in the opening of the insulating film 2, and an electrode metal 5 is formed so as to cover the opening of the insulating film. The protrusion 3 is a cylinder having a diameter of 5 μm, the tip is rounded, and the protrusion is hemispherical. Further, the surface of the protrusion 3 is covered with the electrode metal 5. A bump 7 for connection is formed on the drive IC chip 8, and the TFT array substrate and the drive IC chip 8 are bonded and fixed by a thermosetting resin 6. The metal wiring 4, the electrode metal 5, and the bumps 7 of the driving IC chip are electrically connected. In this embodiment, the bump pitch of the driving IC chip is narrow, but the aggregation of the conductive fine particles 33 generated in FIG. 8 does not occur, so that no short circuit occurs between the electrode metals.

  FIG. 11 is a schematic view partially showing electrode pads in a TFT array substrate when COG mounting is performed on a drive IC chip in which electrodes or bumps are elongated and arranged in a staggered rectangular shape. In the figure, 5 is an electrode metal, 4 is a metal wiring, 10 is a connection opening, 11 is a bottom surface of the connection opening, 3 is a protrusion formed by etching the insulating film, and the surface is covered with the electrode metal. ing. L1 is 85 μm in the vertical dimension of the bottom surface of the opening in the insulating film, and W1 is 16 μm in the horizontal dimension, which is the same as the bump size of the driving IC chip. W2 is the distance between adjacent electrode metals and is 4 μm. The protrusion 3 has a semispherical shape with a diameter of 4 μm. Although the figure shows five protrusions per electrode pad, the conduction resistance between the drive IC bump and the electrode metal can be stably obtained if the number is 3 or more and 10 or less.

  FIG. 12 is a schematic diagram of an electrode pad portion in the TFT array substrate of the present embodiment, which is an input portion of a driving IC driver. In the figure, 5 is an electrode metal, 4 is a metal wiring, 10 is an opening for connection, 11 is a bottom surface of the connection opening, 3 is a protrusion that has been etched in the insulating film, and the surface is covered with the electrode metal. Yes. L2 is 50 μm in the vertical dimension of the bottom surface of the opening in the insulating film, and W3 is 50 μm in the horizontal dimension, which is the same as the bump size of the driving IC chip. W4 is the distance between adjacent electrode metals and is 4 μm. The protrusion 3 has a semispherical shape with a diameter of 4 μm. Although the figure shows 12 protrusions per electrode pad, the conduction resistance between the driving IC bump and the electrode metal was stably obtained when the number was 5 or more and 12 or less. The protrusion 3 in FIG. 11 and the protrusion 3 in FIG. 12 need not be the same size and shape. In particular, when there is a difference in the thickness of the metal wiring, the difference in thickness of the metal wiring can be absorbed by changing the height of the protrusion 3, and the conduction resistance can be stabilized.

  FIG. 13 is a cross-sectional view of a state in which a driving IC chip is mounted on a TFT array substrate of a liquid crystal display element. On the transparent substrate 1, an inorganic insulating film 2b and an organic insulating film 2a are formed. The protrusion 3 has a laminated structure of an inorganic insulating film 2b and an organic insulating film 2a. On the transparent substrate 1, metal wiring 4 and electrode metal 5 for gate lines and source lines are formed, and a mounting portion of the TFT array substrate of the liquid crystal display element is configured. Bumps 7 for connection are formed on the drive IC chip 8, the TFT array substrate and the drive IC chip are bonded by the thermosetting resin 6, and the electrode metal 5 and the bumps 7 are electrically connected. The inorganic insulating film 2b is a silicon film or a polycrystalline silicon film having a thickness of 0.1 to 0.8 μm. If the protrusions 3 are formed using only the inorganic film, the protrusions are not easily crushed when the bumps of the driving IC chip are pressure-bonded to the TFT array, causing a conduction failure. When an organic film is formed on the inorganic film, the organic film has a lower hardness than the inorganic film, so that the organic film in the protrusions is crushed and it is easy to obtain conduction. In order to form the protrusions, the insulating film needs to have a thickness of 1 μm or more. However, since the inorganic film is formed by sputtering, the cost increases to form a thickness of 1 μm. . Furthermore, the insulating characteristic as an insulating film can be improved by using a laminated structure of an inorganic film and an organic film. The conduction resistance can be stabilized by the structure in which the inorganic film and the organic film are laminated as shown in FIG.

  FIG. 14 is a cross-sectional view of a state in which a driving IC chip is mounted on a TFT array substrate of a liquid crystal display element. An organic insulating film 2 a is formed on the transparent substrate 1. 3 is a protrusion. A metal wiring 4 and an electrode metal 5 for gate lines and source lines are formed to constitute a mounting portion of a TFT array substrate of a liquid crystal display element. A bump 7 for connection is formed on the drive IC chip 8. The TFT array substrate and the driving IC chip are bonded by the adhesive 12. Thereby, the electrode metal 5 and the bump 7 are electrically connected. The adhesive 12 may be either an epoxy-based or silicon-based thermosetting type or an ultraviolet curing type as long as the driving IC chip and the TFT array substrate are fixed. The conduction resistance can be stabilized with a simple configuration as shown in FIG.

  Since it is a COG mounting method that does not use conductive fine particles, the mounting of a driving IC chip with a small bump pitch is effective in improving the productivity such as yield and reducing the material cost, and can be applied to any liquid crystal display device.

DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 Insulating film 3 Protrusion 4 Metal wiring 5 Electrode metal 6 Thermosetting resin 7 Bump 8 Drive IC chip 9 Conductive fine particle 10 Opening for connection 11 Bottom surface of opening for connection 12 Adhesive

Claims (9)

A substrate on which metal wiring is formed while constituting a display element;
An insulating film formed on the substrate such that a part of the metal wiring is exposed from the opening;
An electrode metal formed in the opening of the insulating film;
An IC chip having a bump connected to the electrode metal of the opening,
The opening is provided with a protrusion, and the electrode metal is formed to cover the protrusion,
The display device characterized in that the IC chip is electrically connected to the metal wiring when the bump and the electrode metal of the protrusion are in contact with each other.   The display device according to claim 1, wherein the protrusion is formed of the same material as the insulating film.   3. The display device according to claim 1, wherein 3 or more and 12 or less of the protrusions are provided per one of the openings.   The display device according to claim 1, wherein the protrusion has a cylindrical or hemispherical shape with a diameter of 4 μm to 5 μm.   5. The display device according to claim 1, wherein a total area of an upper surface of the protrusion provided in the opening is 2 to 20% of a bottom area of the opening.   The display device according to claim 1, wherein the insulating film is an organic film having a thickness of 1 μm to 4 μm.   The display device according to claim 6, wherein the organic film has a laminated structure of an organic film and an inorganic film. Forming metal wiring on the substrate;
Forming an insulating film on the substrate so as to cover the metal wiring;
Providing an opening in the insulating film so that a part of the metal wiring is exposed, and forming a protrusion in the opening;
Forming an electrode metal on the surface of the opening, and forming the electrode metal on the surface of the protrusion;
A step of electrically connecting the IC chip and the metal wiring by aligning the bump of the IC chip with the opening and bringing the bump and the electrode metal of the protrusion into contact;
Manufacturing a display element using a substrate on which the IC chip is mounted.   The method for manufacturing a display device according to claim 8, wherein the protrusion is formed simultaneously with the opening by etching the insulating film.

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