JP2008116795A - Display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display apparatus in which a drive IC is directly mounted on connection terminals on an insulating substrate, the display apparatus suppressing short circuit across the terminals, not complicating the mounting process and having high reliability of connection. <P>SOLUTION: The display apparatus is provided with the insulating substrate 1 formed with a display area and a driving IC4 directly mounted on a connection terminal part formed outside the display area in order to supply signals to the display area 1, and the display apparatus is characterized in that the connection terminal part includes two or more projection parts 10 formed of an insulating material, and the projection parts 10 are covered with a transparent conductive film 11. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a connection structure when a drive circuit is directly mounted on the periphery of a display area on an insulating substrate.

In the liquid crystal display device, a driving circuit (driving IC) is connected to a liquid crystal sandwiched between two insulating substrates, and is stacked on a lighting device (backlight). For example, in a liquid crystal display device using a thin film transistor (TFT), TFTs are arranged in a matrix on one of two insulating substrates (TFT substrate), and more than the other substrate (opposing substrate). The outer shape is superimposed in a protruding form. One pixel is formed for each TFT, and an image signal sent to the pixel is controlled by turning the TFT on and off. Source wiring for inputting an image signal from the source electrode of each TFT is drawn out in parallel with the short side of the insulating substrate, and a connection terminal for connecting the driving IC is formed near the end on the long side of the TFT substrate. Has been. Also, gate wiring for turning on and off the TFT is drawn out from the gate electrode of each TFT in parallel with the long side of the TFT substrate, and the driving IC is connected near the end on the short side of the TFT substrate in the same manner as the source side. A connection terminal is formed. For example, in a form in which the driving IC is directly mounted on an insulating substrate by a COG (Chip On Glass) mounting method, an anisotropic conductive film (ACF: Anisotropic conductive film) is connected to a connection terminal arranged in a portion protruding from the counter substrate in the TFT substrate. The driving IC is directly mounted via a conductive fine particle) in which conductive fine particles are dispersed in an adhesive resin.

In recent years, the number of output pins of drive ICs has been rapidly increasing due to the demand for higher definition of images. Further, in order to reduce the manufacturing cost of the driving IC, the outer shape of the driving IC is shrunk, and the pitch of the driving IC bump is further miniaturized as the number of pins increases. Until now, some measures have been taken for COG mounting with a fine pitch, but as the pitch becomes finer in this way, the area of the bumps has been further reduced. For this reason, the number of ACF conductive particles captured on the bumps is reduced, and there is a problem that the conductive particles are not captured on the bumps. As countermeasures, countermeasures such as increasing the number of conductive particles mixed in the ACF and improving the probability of being captured on the bump are taken. However, with the increase in the number of conductive particles to be mixed, the aggregation of the conductive particles is increased this time, and there is a problem that the adjacent terminals are short-circuited due to the connection (continuity) of the conductive particles.

As a method of simultaneously improving such a probability of capturing conductive particles and simultaneously preventing a short circuit between adjacent terminals due to conductive particle aggregation, a method of forming an ACF in two layers has been devised. This is because conductive particles are blended in the layer facing the connection terminal on the insulating substrate, and the layer facing the bump side of the driving IC is not blended with conductive particles and a layer made of only adhesive resin is formed. It is. When conductive particles in the ACF are thermocompression bonded to the drive IC, the resin close to the drive IC bump side is discharged toward the outside of the drive IC during pressure bonding, and the conductive particles are also discharged together with the resin. Therefore, the conductive particles are blended only in the resin facing the connection terminal on the insulating substrate, and not in the resin close to the drive IC bump side. With such a configuration, it is possible to improve the number of conductive particles trapped in the bumps while suppressing an increase in the amount of conductive particles in the resin, and thus it is possible to achieve both countermeasures against poor conduction and shorts between adjacent terminals.

In addition, as another conventional technique, on the projection formed on the glass substrate, a reflective film that reflects light and a conductive metal film and a protective film are formed, and an electrode on the film carrier; Some are electrically connected by pressure bonding with a conductive adhesive such as ACF (for example, see Patent Document 1).

Japanese Patent Laying-Open No. 2002-6330 (FIG. 1)

  However, when the two-layer ACF structure is used as described above, since conductive particles are used in the lower layer, it is not possible to completely suppress the occurrence of a short circuit between terminals due to a series of conductive particles. In recent years, drive ICs used in liquid crystal display devices using TFTs have increased in number of pins for the purpose of higher resolution and cost reduction, and accordingly, the demand for fine pitch bonding technology has been increasing. The narrower the pitch, the higher the possibility that a short circuit between terminals will occur.

  Moreover, in the prior art of the above-mentioned Patent Document 1, the terminal on the insulating substrate and the electrode on the film carrier are connected, and the joining technique when the drive IC is directly mounted on the insulating substrate is described. No mention is made, and there is a problem in connection reliability when the drive IC is directly mounted on the insulating substrate using the ACF. In this prior art, a protective film is formed on the terminal-side connection surface on the insulating substrate connected to the electrode on the film carrier, and the surface of the protective film portion is mechanically lightly polished. In this case, since the mounting was performed after the metal film was removed and the underlying metal film was exposed, the mounting process was complicated.

The present invention has been made in view of such a problem, and in a display device in which a driving IC is directly mounted on a connection terminal on an insulating substrate, a short circuit between terminals is suppressed by not using an anisotropic conductive film. The object is to obtain high connection reliability without complicating the mounting process.

The present invention provides an insulating substrate on which a display area is formed, and a driving IC directly mounted on a connection terminal portion formed outside the display area on the insulating substrate in order to supply a signal to the display area. The connection terminal portion includes at least a plurality of protrusions made of an insulating material, and the protrusions are covered with a conductive film.

  According to the present invention, when a drive IC is directly mounted on a connection terminal on an insulating substrate, a short circuit between adjacent connection terminals can be suppressed and a display device with high connection reliability can be obtained.

Embodiment 1 FIG.
A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an external view of a display device according to Embodiment 1 of the present invention, and FIG. 2 is a mounting sectional view (AA sectional view) of a drive IC of the display device according to Embodiment 1 of the present invention.

FIG. 1 shows an external view of, for example, a small liquid crystal display device using a so-called COG mounting method in which a driving IC is directly mounted on an insulating substrate. In FIG. 1, a liquid crystal is sandwiched between an insulating substrate 1 and a counter substrate 2 provided with, for example, a color filter. A polarizing plate 3 is attached to the front surface of the counter substrate 2 and the back surface (not shown) of the insulating substrate 1. A display region composed of a plurality of pixels is formed on the insulating substrate 1 and wiring for supplying signals to the pixels is formed, and is disposed at a portion protruding from the counter substrate at the end of the insulating substrate. A resin material 5 made of a thermosetting resin or the like is disposed on the connecting terminal portion. A driving IC 4 is directly mounted on the resin material 5. A flexible circuit board 6 for inputting a signal to the drive IC 4 is provided via an anisotropic conductive film (ACF) 7 at the end of the insulating substrate further than the area where the drive IC 4 is mounted. It is connected.

2 is a cross-sectional view (AA cross-sectional view) of the connection terminal portion on the insulating substrate on which the driving IC in FIG. 1 is mounted, and either SiO ₂ or SiN or a mixture thereof on the insulating substrate 1. The 1st insulating film 8 comprised by these is formed. On the first insulating film 8, an opaque metal film 9 mainly made of any one of Cr, Al, Mo, and Cu or a laminated film thereof is formed and patterned by etching to constitute a connection terminal. A second insulating film 10 made of either SiO ₂ or SiN or a mixture thereof is formed on the opaque metal film 9. By partially removing the second insulating film 10 by etching, it is possible to expose a necessary portion of the underlying opaque metal film 9.

In the connection terminal portion that is overlapped with and directly connected to the bump 12 of the driving IC 4, the second insulating film 8 is left in an island shape, and a protrusion is formed. A transparent conductive film 11 is formed so as to cover the island-shaped protrusions made of these insulating films 10 and the region other than the protrusions on the opaque conductive film 9. With such a configuration, electrical conduction is obtained between the opaque metal film 9 and the transparent conductive film 11 formed on the surface of the projecting portion made of the second insulating film 10 to form a projecting electrode. By applying a thermosetting resin material 5 on these protruding electrodes and heating the bumps 12 of the driving IC 4 made of Au as a main material while applying pressure on the protruding electrodes, the bumps of the driving IC 4 12 and the protruding electrode are electrically connected. Therefore, the conductive material 5 can be a material that does not contain conductive particles. Since the Au of the bump 12 of the driving IC 4 is softer than the insulating film of the protruding electrode (and SiO ₂ or SiN), the protruding electrode is connected so as to bite into the bump 12 of the driving IC 4. For this reason, even if the connection terminal portion is exposed to, for example, a high-temperature and high-humidity environment and the thermosetting resin material 5 swells, the protruding electrodes of the connection terminal portion bite into the bumps 12 of the drive IC 4, so that It is possible to maintain high connection reliability without being easily lost. The height of the protruding electrode is preferably higher because it protrudes into the bump 12 of the driving IC 4, and is preferably at least 0.5 μm or more. As for the width of the protruding electrode, the smaller one is likely to bite into the bump 12 of the driving IC 4 and is preferably at least 10 μm or less. The larger the number of protruding electrodes per bump of the driving IC 4 is, the more preferable, and it is preferable that the number is at least three.

  In the above description, the transparent conductive film formed simultaneously with the pixel electrode is formed so as to cover the island-shaped protrusion and the region other than the protrusion on the opaque conductive film. An opaque conductive film that is formed at the same time as the gate line or the source line that constitutes may be formed.

  As described above, with the configuration of this embodiment, a liquid crystal display device with high connection reliability can be easily obtained when the drive IC is mounted directly on an insulating substrate.

Embodiment 2. FIG.
A second embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a mounting cross-sectional view (AA cross-sectional view) of the drive IC of the display device according to the second embodiment of the present invention, and FIGS. 4 and 5 are other diagrams of the drive IC of the display device according to the second embodiment of the present invention. It is mounting sectional drawing (AA sectional drawing). 3 to 5, the same components as those in FIGS. 1 to 2 are denoted by the same reference numerals, and differences from the first embodiment will be described.

In FIG. 3, as in the first embodiment, the second insulating film 10 is formed in an island shape to form a protrusion, and an organic resin material is formed on the second insulating film. A film 13 is formed to form a protruding electrode. As in the first embodiment, a transparent conductive film 11 is formed so as to cover the exposed portion and the protruding portion of the opaque metal film 9. As in the first embodiment, the thermosetting resin material 5 is applied on the protruding electrodes, and the bumps 12 of the driving IC 4 and the protruding electrodes are electrically connected by heating the bumps 12 of the driving IC 4 while applying pressure. It is connected to the. In the present embodiment, since the protruding electrode further includes the organic film 13, when the bump 12 of the driving IC 4 is pressed against the connection terminal portion, the organic film 13 is elastically deformed in a crushed shape. ing. In this state, the periphery of the bumps 12 and the protruding electrodes of the driving IC 4 are fixed by the thermosetting resin material 5, so that the surface of the bumps 12 and the protruding electrodes on the driving IC 4 are pressed against each other by the repulsive force of the organic film 13. A good contact resistance can be obtained. For this reason, as in the first embodiment, even if the thermosetting resin material 5 is swollen by being exposed to a high-temperature and high-humidity environment, the organic film 13 of the protruding electrode is elastically deformed. The surface of the bump 12 of the driving IC 4 and the surface of the bump electrode are kept in contact with each other, so that conduction can be maintained. In the present embodiment, the resin material 5 that does not include conductive particles can be used as in the first embodiment. In addition, since the organic film 13 is used in the present embodiment, it is possible to stack the layer thickness as thick as generally 2 to 3 μm, and it becomes easy to secure the height of the protruding portion, It becomes possible to connect the bumps of the driving IC and the connection terminals more favorably.

FIGS. 4 and 5 show the case where the first insulating film 8 in FIGS. 2 and 3 is formed after the opaque metal film 9. The first insulating film 8 and the second insulating film are shown in FIGS. 10 are doubly stacked to form a protrusion (in the case of FIG. 5, the protrusion is further formed including an organic film). In this case as well, the effect is the same as described above, and the structure is such that the protruding electrodes are more likely to bite into the bumps 12 of the driving IC 4 as the insulating film becomes thicker.

  According to the above embodiment, since it is possible to connect terminals without interposing conductive particles like an anisotropic conductive film, a short circuit between adjacent terminals can be prevented and connection with high reliability can be easily performed. It is possible to obtain Further, as in the first embodiment, the above description shows a structure in which a transparent conductive film formed simultaneously with the pixel electrode is formed so as to cover the exposed portion and the protruding portion of the opaque metal film. An opaque conductive film that is formed at the same time as the gate line or the source line to be formed may be formed.

Further, in the above embodiment, by selecting a smaller elastic modulus of the insulating film formed on the protrusion than the elastic modulus after curing of the resin material used for connection, the protrusion can be formed at the time of pressure bonding. It is also possible to keep the flat state and maintain contact between the terminals by the elasticity of the protrusions.

Although the display device using liquid crystal has been described as the above embodiment, the present invention is not limited to this, and is not only applicable to any display device using an electroluminescence (EL) element, The present invention can be applied to any device in which terminals are connected with an anisotropic conductive film, such as between a semiconductor element and a circuit board or a circuit board.

It is an external view of the display apparatus in Embodiment 1 of this invention. It is mounting mounting sectional drawing of the drive IC of the display apparatus in Embodiment 1 of this invention. It is mounting sectional drawing of the drive IC of the display apparatus in Embodiment 2 of this invention. It is other mounting sectional views of the drive IC of the display device in Embodiment 2 of the present invention. It is other mounting sectional views of the drive IC of the display device in Embodiment 2 of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Insulating substrate, 2 Opposite substrate, 3 Polarizing plate, 4 Driving IC, 5 Resin material, 6 Flexible circuit board, 7 Anisotropic conductive film, 8 1st insulating film, 9 Opaque metal film, 10 2nd insulation Film, 11 Transparent conductive film, 12 Bump, 13 Organic film

Claims (6)

An insulating substrate having a display area formed thereon;
In order to supply a signal to the display area, a driving IC directly mounted on a connection terminal portion formed outside the display area on the insulating substrate;
A display device comprising:
The display device, wherein the connection terminal portion has a plurality of protrusions made of an insulating material, and the protrusions are covered with a conductive film. The display device according to claim 1, wherein the protrusion includes an opaque metal film between the protrusion and the insulating substrate. The display device according to claim 1, wherein the protrusion includes SiO ₂ or SiN. The display device according to claim 1, wherein the protrusion includes an organic resin film. The display device according to claim 1, wherein the conductive film is a transparent conductive film in the same layer as a pixel electrode that forms the display region. The display device according to claim 1, wherein the drive IC and the connection terminal portion are connected by a resin material that does not include conductive particles.

Images