Organic electroluminescence display panel and method for manufacturing the same

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention is an organic electroluminescent display in which organic EL elements provided with a light emitting layer made of a thin film of an organic electroluminescent material are arranged in a matrix, utilizing the electroluminescent effect of the organic compound material that emits light by injecting an electric current. It relates to a panel (hereinafter referred to as an organic EL display panel).

【0002】

[Conventional technology]

In recent years, organic EL display panels have been regarded as promising as display devices for mobile terminals, mobile PCs, mobile phones and the like. The organic EL display panel has features such as wide viewing angle, high contrast, and excellent color reproducibility because the pixels themselves are self-luminous, so no backlight is required, and full-color display is possible without using color filters. In addition, because it has characteristics such as high brightness, thinness, and excellent response characteristics, each company is actively developing it for mobile phones and PDAs (Personal Digital Assistants).

【0003】

The organic EL display panel is an organic electroluminescent element (hereinafter referred to as organic) on individual pixel electrodes arranged in a matrix, as described in, for example, JP-A-9-115672 and JP-A-8-227276. An EL element) is formed, electrons are injected from the cathode by the voltage applied to the pixel electrode, and holes are injected from the anode, and the electrons and holes are recombined to emit light for display. Is generated at a portion where the cathode and the anode overlap with each other across the organic electroluminescent material layer.

【0004】

Figure 7 shows the configuration of a conventional organic EL display panel. On the glass substrate which is the transparent substrate 30, a plurality of island-shaped transparent electrodes 31 made of indium tin oxide (ITO) arranged side by side in a matrix and non-linear elements 32 connected to the transparent electrodes 31, for example, each other. The connected thin film transistors (TFTs) are formed by photolithography, vacuum deposition technology, and the like. A flattening film 39 made of a photosensitive resin is formed on the non-linear element 32 for flattening by several microns, and the non-linear element 32 and the transparent electrode 31 are electrically connected through an opening 40 in which the flattening film 39 is opened by photolithography. Has been done. A protrusion 38 made of a photosensitive resin is formed on the flattening film 39. The organic medium of the hole transport layer 33, the light emitting layer 34 and the electron transport layer 35 is formed of a thin film on the transparent electrode 31 serving as an anode, and a metal thin film of the cathode 36 is formed on the uppermost layer. These thin films are sequentially formed by, for example, a vacuum vapor deposition method, and holes injected from the transparent electrode 31 are formed by selectively applying a DC voltage between the transparent electrode 31 as an anode and the cathode 36. The electrons injected through the hole transport layer 33 and from the cathode 36 pass through the electron transport layer 35 and reach the light emitting layer 34, respectively, and the electrons and holes are recombined, from which light emission 37 having a predetermined wavelength is generated. Light emission can be displayed from the transparent substrate 30 side. Further, at this time, by forming light emitting layers 34 having different light emitting substances for each color such as red light emitting 37-R, green light emitting 37-G, and blue light emitting 37-B individually on the transparent electrode 31 in a juxtaposed arrangement. It is possible to perform full-color display.

【0005】

[Problems to be Solved by the Invention]

However, in the organic EL display panel having such a configuration, the organic EL elements formed on the individual pixel electrodes of the panel have extremely low heat resistance in terms of material properties. Therefore, in the conventional heat-bonding method using an anisotropic conductive film (ACF) on a driver IC chip or flexible wiring board on a panel, the heat of the mounting part is transferred from the panel board to the pixels and heated, and is heated on each pixel. The formed organic EL element was deteriorated by heat.

【0006】

Fig. 8 shows the panel surface temperature with respect to the mounting temperature T1 and the distance L from the mounting part by the heat bonding method using the conventional ACF (anisotropic conductive film) using a general glass substrate with a panel thickness of 0.7 mm. It is a graph which measured the relationship of T2. The connection time is 15 seconds. According to this, when the mounting temperature T1 in heat crimping of a driver IC chip or flexible wiring board using a conventional anisotropic conductive film (ACF) is 190 ° C, the panel surface temperature at a distance L of 2 mm away from the mounting part. The results show that T2 reaches 90 ° C or higher, which is much higher than the general heat resistant temperature of 80 ° C for organic EL materials. That is, the organic EL material provided at a distance of 2 mm from the mounting portion undergoes thermal deterioration depending on the mounting temperature, and in the organic EL display panel, the emission brightness of each pixel is significantly reduced, and at the same time, the display quality is impaired. The reliability of the organic EL display panel is significantly reduced. Therefore, in the organic EL display panel, the conventional mounting method using an anisotropic conductive film (ACF) has become extremely difficult.

【0007】

In addition, considering the application to small mobile terminal devices such as mobile phones, it is difficult to design the panel size to be larger than necessary, and a narrow frame design that reduces the area other than the effective pixel area is possible. This is done, but this reduces the distance between the pixel area and the edge of the panel substrate, and in a 2-3 inch organic EL display panel, the distance between the connection and the pixel area is approximately 1 mm. Therefore, as shown in Fig. 8, when the driver IC chip and the flexible wiring board are connected at the mounting temperature T1 at the conventional 190 ° C, the panel surface temperature T2 at a distance L of 1 mm away from the mounting part is 100 ° C at the maximum. The temperature becomes higher than the above, and the mounting method using an anisotropic conductive film (ACF) cannot be applied to an organic EL display panel with a narrow frame.

【0008】

Therefore, a method of increasing the distance from the connection portion to the pixel electrode area in order to reduce the heat effect from the heat transfer at the time of connection is conceivable, but then the frame of the panel becomes remarkably wide and the panel size becomes an effective pixel. It is extremely large with respect to the area, and it is extremely difficult to apply it to small mobile terminal devices such as mobile phones and mobile PCs, which is not realistic.

【0009】

Furthermore, in recent years, attempts have been made to make the panel itself thinner for the purpose of making the device thinner, and in order to do so, a very thin substrate with a panel substrate thickness of 0.5 mm is used. For this reason, in the conventional heating and pressurizing connection method, high-temperature and high-pressure connections cause cracks in the panel substrate, chips, thermal expansion / deterioration of peripheral parts, etc., and the manufacturing yield of the organic EL display panel is significantly reduced. , The cost was soaring.

【0010】

[Means for solving problems]

The present invention has been made to solve the above-mentioned problems, and is conductive when COG mounting of a driver IC chip and when electrically connecting a connection electrode portion of an organic EL display panel and a flexible wiring board. Using an insulating photocurable resin mixed with particles, the organic EL element formed in the pixel region of the organic EL display panel is not thermally deteriorated by electrically connecting and fixing, and the organic EL element has a narrow frame. It is possible to realize an EL display panel.

【0011】

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

【0012】

(Embodiment 1) The first embodiment of the present invention will be described. Figure 1 shows an organic EL display panel with a configuration in which a semiconductor chip, which is a driver IC for driving, is mounted. In FIG. 1, 1 is an organic EL panel, 2 is a substrate, 3 is a pixel region, 4 is an organic EL element, 5 is a connection electrode, 15 is a semiconductor chip, 16 is a protrusion electrode, 8 is an insulating photocurable resin, and 9 Is conductive particles, 10 is light irradiation, and 11 is a sealing cap. The substrate 2 of the organic EL panel 1 needs to be light transmissive.

【0013】

In the present invention, an insulating photocurable resin 8 having an insulating resistance of about 10E8Ω · cm is used. The insulating photocurable resin 8 is cured by irradiating the contained photocurable resin composition with light 10, and the light irradiation 10 includes, for example, visible light, ultraviolet (UV) light, or the like. In general, ultraviolet light having a large amount of irradiation energy is preferable. As a specific irradiation method, a light irradiator using a high-pressure mercury lamp, an ultra-high pressure mercury lamp, or the like can be used.

【0014】

The composition contained in the insulating photocurable resin 8 includes those whose main components are (meth) acrylic, polyimide, polyamide, silicone and the like, but any of them may be used. Examples of these polymerization groups include an α-chloroacrylate group, a styryl group, a vinyl group, a vinyl ester group, a vinyl ketone group, and the like, in addition to an acrylic group and a methacrylic group.

【0015】

In addition, a photoinitiator can be added to the composition of these insulating photocurable resins 8. Examples of the photoinitiator include acetophenone, benzophenone, Michler ketone, benzyl, benzoin, benzoin ether, benzyl ether, benzyl dimethyl ketal, thioxanthone and derivatives thereof.

【0016】

The insulating photocurable resin 8 contains conductive particles 9 for electrically connecting the protruding electrode 16 of the semiconductor chip 15 and the connecting electrode 5 of the organic EL panel 1. As the conductive particles 9, those having a diameter of about 10 μm or less can generally be used. On the other hand, in recent years, when the pitch of the connecting electrodes 5 is narrowed, a short circuit may occur between adjacent electrodes after connection, and as a countermeasure, conductive particles 9 having a particle size of about 5 μm can also be used.

【0017】

As the material of the conductive particles 9, metal particles such as nickel and gold, organic resins such as polystyrene, and particles obtained by coating the surface of an inorganic material such as glass and ceramics with a conductive thin film such as nickel and gold are used. Can be done. Further, as the particles, those having conductivity can be used, but those having low resistance are preferable in order to prevent a voltage drop at the connection portion. The conductive particles 9 may be mixed with the insulating photocurable resin 8 in an amount of about 0.001 to 20 wt% with respect to the photocurable resin composition of the insulating photocurable resin 8, although it depends on the particle size. When mixing, it is desirable to knead well and mix while applying vibration such as ultrasonic waves to reduce the distribution variation of the conductive particles 9 in the insulating photocurable resin 8.

【0018】

Further, the semiconductor chip 15 is formed with a protruding electrode 16 made of Au bumps having a height of 5 to 10 μm by a plating method.

【0019】

Next, with reference to FIG. 2, a method for manufacturing an organic EL display panel according to the first embodiment of the present invention will be described. In FIG. 2A, the organic EL element 4 is formed in the pixel region 3 formed on the organic EL panel 1, and the organic EL element 4 is sealed with a sealing cap 11 in order to prevent deterioration due to humidity in the atmosphere. Is being done. When mounting such an organic EL panel 1 and a semiconductor chip that is a driver IC for driving, an insulating photocurable resin 8 in which conductive particles 9 are mixed and kneaded is used as a connection electrode 5 of the organic EL panel 1 or a semiconductor. Apply to at least one of the chips 15 surfaces (not shown). At this time, the coating amount of the insulating photocurable resin 8 is preferably an amount or more so that the entire surface on which the connection electrodes 5 of the organic EL panel 1 overlap is covered with the insulating photocurable resin 8.

【0020】

Although the case where the insulating photocurable resin 8 to be applied is liquid is described here, the insulating photocurable resin 8 may be in the form of a sheet or a film.

【0021】

In FIG. 2B, the semiconductor chip 15 is held face-down on the connection electrode 5 of the organic EL panel 1 by the pressurizing jig 13, and the connection electrode 5 of the organic EL panel 1 and the protrusion electrode 16 of the semiconductor chip 15 are formed. Align 12 so that they face each other.

【0022】

Next, in FIG. 2C, the pressurizing jig 13 is gradually lowered, and the protruding electrode 16 of the semiconductor chip 15 is crimped to the connecting electrode 5 of the organic EL panel 1. At this time, the pressure by the pressurizing jig 13 is 15 to 30 kg / cm.²Is.

【0023】

At this time, the semiconductor chip 15 may be crimped to the organic EL panel 1 in a heated state. Further, the semiconductor chip 15 may be crimped while the organic EL panel 1 is heated. In any case, it goes without saying that the heating temperature is set to a low temperature at which the organic EL element 4 formed in the pixel region 3 does not thermally deteriorate. By this heating, the viscosity of the insulating photocurable resin 8 is lowered, the fluidity of the insulating photocurable resin 8 by pressurization is facilitated, and air bubbles are interposed between the semiconductor chip 15 and the organic EL panel 1. It has the effect of preventing it.

【0024】

Furthermore, when the insulating photocurable resin 8 to be used is in the form of a sheet or a film, the sheet-shaped or film-shaped insulating photocurable resin 8 is softened in a short time by heating to a low-viscosity liquid state. It also has the effect of being able to do it.

【0025】

Next, in FIG. 3A, with the semiconductor chip 15 pressurized 14 by the pressurizing jig 13, light irradiation 10 by ultraviolet rays is performed from the back surface side of the substrate 2 of the organic EL panel 1. For light irradiation, a light irradiator using a high-pressure mercury lamp, an ultra-high pressure mercury lamp, or the like is used to irradiate light from the light-transmitting substrate 2 side. The amount of irradiation energy depends on the type of composition, but usually UV light with a wavelength of 365 nm is 1000 mJ / cm.²To the extent. Here, it is also possible to perform aftercure by leaving it in a state where it has been cured by about 50% by light irradiation. The light irradiation time is about several seconds to several minutes, although it depends on the composition of the insulating photocurable resin 8. By this irradiation with ultraviolet rays, the conductive particles 9 sandwiched between the connection electrode 5 of the organic EL panel 1 and the protrusion electrode 16 of the semiconductor chip 15 electrically connect the two, and the insulating photocuring By photocuring the mold resin 8, the electrical connection between the connection electrode 5 of the organic EL panel 1, the semiconductor chip 15, and the protrusion electrode 16 is maintained. By heating the pressurizing jig 13 at a temperature below which the organic EL element 4 is not subjected to thermal deterioration, the pressurizing jig 13 can be pressurized 14, the amount of light irradiation can be reduced, and the light irradiation time can be shortened. This can be done and the damage to the connection to the substrate can be reduced.

【0026】

Next, in FIG. 3B, after the predetermined light irradiation 10 is completed, the pressurization by the pressurizing jig 13 is released to complete the mounting of the semiconductor chip 15 on the organic EL panel 1.

【0027】

After the above, the organic EL display panel (and the semiconductor chip) is heated at a low temperature at which the organic EL element 4 formed in the pixel region 3 does not undergo thermal deterioration, and the insulating photocurable resin 8 is cured. Is also good.

【0028】

In addition, by changing the light irradiation amount and light irradiation time, it is possible to reduce the pressing force by the pressurizing jig 13, and it is possible to make a low-damage connection without cracking or chipping even on a thin substrate. Become.

【0029】

(Embodiment 2) Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 4 shows an organic EL display panel having a configuration in which a flexible wiring board is connected to the organic EL display panel. In FIG. 4, 1 is an organic EL panel, 2 is a substrate, 3 is a pixel region, 4 is an organic EL element, 5 is a connection electrode, 6 is a flexible wiring board, 7 is a wiring electrode, and 8 is an insulating photocurable resin. 9 is conductive particles, 10 is light irradiation, and 11 is a sealing cap. Since the substrate 2 of the organic EL panel 1 or the flexible wiring substrate 6 is irradiated with light, either of them needs to be light-transmitting.

【0030】

In the present invention, an insulating photocurable resin 8 having an insulating resistance of about 10E8Ω · cm is used. The insulating photocurable resin 8 is cured by irradiating the contained photocurable resin composition with light 10, and the light irradiation 10 includes, for example, visible light, ultraviolet (UV) light, or the like. In general, ultraviolet light having a large amount of irradiation energy is preferable. As a specific irradiation method, a light irradiator using a high-pressure mercury lamp, an ultra-high pressure mercury lamp, or the like can be used.

【0031】

The composition contained in the insulating photocurable resin 8 includes those whose main components are (meth) acrylic, polyimide, polyamide, silicone and the like, but any of them may be used. Examples of these polymerization groups include an α-chloroacrylate group, a styryl group, a vinyl group, a vinyl ester group, a vinyl ketone group, and the like, in addition to an acrylic group and a methacrylic group.

【0032】

In addition, a photoinitiator can be added to the composition of these insulating photocurable resins 8. Examples of the photoinitiator include acetophenone, benzophenone, Michler ketone, benzyl, benzoin, benzoin ether, benzyl ether, benzyl dimethyl ketal, thioxanthone and derivatives thereof.

【0033】

The insulating photocurable resin 8 contains conductive particles 9 for electrically connecting the flexible wiring board 6 and the connection electrode 5 of the organic EL panel 1. As the conductive particles 9, those having a diameter of about 10 μm or less can generally be used. On the other hand, in recent years, when the pitch of the connecting electrodes 5 is narrowed, a short circuit may occur between adjacent electrodes after connection, and as a countermeasure, conductive particles 9 having a particle size of about 5 μm can also be used.

【0034】

As the material of the conductive particles 9, metal particles such as nickel and gold, organic resins such as polystyrene, and particles obtained by coating the surface of an inorganic material such as glass and ceramics with a conductive thin film such as nickel and gold are used. Can be done. Further, as the particles, those having conductivity can be used, but those having low resistance are preferable in order to prevent a voltage drop at the connection portion. The conductive particles 9 may be mixed with the insulating photocurable resin 8 in an amount of about 0.001 to 20 wt% with respect to the photocurable resin composition of the insulating photocurable resin 8, although it depends on the particle size. When mixing, it is desirable to knead well and mix while applying vibration such as ultrasonic waves to reduce the distribution variation of the conductive particles 9 in the insulating photocurable resin 8.

【0035】

Next, the method for manufacturing the organic EL display panel according to the second embodiment of the present invention will be described with reference to FIG. In FIG. 5A, the organic EL element 4 is formed in the pixel region 3 formed on the organic EL panel 1, and the organic EL element 4 is sealed with a sealing cap 11 in order to prevent deterioration due to humidity in the atmosphere. Is being done. When connecting the organic EL panel 1 and the flexible wiring board 6 in this way, the insulating photocurable resin 8 in which the conductive particles 9 are mixed and kneaded is used as the connection electrode 5 of the organic EL panel 1 or the flexible wiring board 6 (FIG. Apply to at least one of the wiring electrodes 7 (not shown). At this time, the coating amount of the insulating photocurable resin 8 is preferably an amount or more such that the entire surface on which the connection electrodes 5 of the organic EL panel 1 overlap is covered with the insulating photocurable resin 8. Although the case where the insulating photocurable resin 8 to be applied is liquid is described here, the insulating photocurable resin 8 may be in the form of a sheet or a film.

【0036】

In FIG. 5 (b), the flexible wiring board 6 is arranged on the connection electrode 5 of the organic EL panel 1, and the connection electrode 5 of the organic EL panel 1 and the wiring electrode 7 of the flexible wiring board 6 are aligned so as to face each other. Do 12.

【0037】

Next, in FIG. 5C, the wiring electrode 7 of the flexible wiring board 6 is gradually crimped to the connection electrode 5 of the organic EL panel 1 by the pressurizing jig 13. At this time, the pressure by the pressurizing jig 13 is 15 to 30 kg / cm.²Is. At this time, the flexible wiring board 6 may be crimped to the organic EL panel 1 in a heated state. Further, the flexible wiring board 6 may be crimped while the organic EL panel 1 is heated. In any case, it goes without saying that the heating temperature is set to a low temperature at which the organic EL element 4 formed in the pixel region 3 does not thermally deteriorate. By this heating, the viscosity of the insulating photocurable resin 8 is lowered, the fluidity of the insulating photocurable resin 8 by pressurization is facilitated, and air bubbles are interposed between the flexible wiring board 6 and the organic EL panel 1. Has the effect of preventing.

【0038】

Furthermore, when the insulating photocurable resin 8 to be used is in the form of a sheet or a film, the sheet-shaped or film-shaped insulating photocurable resin 8 is softened in a short time by heating to a low-viscosity liquid state. It also has the effect of being able to do it.

【0039】

Next, in FIG. 6A, with the flexible wiring board 6 pressurized by the pressurizing jig 13, light irradiation 10 by ultraviolet rays is performed from the back surface side of the substrate 2 of the organic EL panel 1. For light irradiation, a light irradiator using a high-pressure mercury lamp, an ultra-high pressure mercury lamp, or the like is used to irradiate light from the light-transmitting substrate 2 side. The amount of irradiation energy depends on the type of composition, but usually UV light with a wavelength of 365 nm is 1000 mJ / cm.²To the extent. Here, it is also possible to perform aftercure by leaving it in a state where it has been cured by about 50% by light irradiation. The light irradiation time is about several seconds to several minutes, although it depends on the composition of the insulating photocurable resin 8. By irradiating with this ultraviolet light, the conductive particles 9 sandwiched between the connection electrode 5 of the organic EL panel 1 and the wiring electrode 7 of the flexible wiring substrate 6 electrically connect the two, and the insulating photocuring By photocuring the mold resin 8, the electrical connection between the connection electrode 5 of the organic EL panel 1 and the wiring electrode 7 of the flexible wiring substrate 6 is maintained. By heating the pressurizing jig 13 at a temperature below which the organic EL element 4 is not subjected to thermal deterioration, the pressurizing jig 13 can be pressurized 14, the amount of light irradiation can be reduced, and the light irradiation time can be shortened. This can be done and the damage to the connection to the substrate can be reduced.

【0040】

Next, in FIG. 6B, after the predetermined light irradiation 10 is completed, the connection of the flexible wiring board 6 in the organic EL panel 1 is completed by releasing the pressurization by the pressurizing jig 13.

【0041】

After the above, the organic EL display panel (and the semiconductor chip) is heated at a low temperature at which the organic EL element 4 formed in the pixel region 3 does not undergo thermal deterioration, and the insulating photocurable resin 8 is cured. Is also good.

【0042】

In addition, by changing the light irradiation amount and light irradiation time, it is possible to reduce the pressing force by the pressurizing jig 13, and it is possible to make a low-damage connection without cracking or chipping even on a thin substrate. Become.

【0043】

[Effect of the invention]

As described above, the effect of the present invention is that the driver IC chip of the organic EL display panel is mounted by the insulating photocurable resin mixed with the conductive particles, and the flexible wiring board is electrically connected and fixed to the organic EL display panel. An organic EL display with excellent display quality and reliability, with no thermal deterioration due to the thermal effect on the organic EL element with extremely low heat resistance formed in the pixel region and no decrease in the emission brightness of each pixel. It becomes possible to realize a panel.

【0044】

Further, since there is no heating process when mounting the driver IC chip and the flexible wiring board, the distance from the pixel region to the mounting portion can be reduced. Therefore, the panel size with respect to the effective pixel area can be reduced, and an organic EL display panel with a narrow frame that can be applied to small mobile terminal devices such as mobile phones and mobile PCs can be realized at low cost.

【0045】

Furthermore, since there is no damage to the organic EL display panel due to high-temperature heating and high-pressure pressurization, cracks, chips, thermal expansion / deterioration of peripheral parts, etc. occur in the panel board mounting process of the driver IC chip and flexible wiring board. However, it is possible to improve the manufacturing yield and reduce the cost of organic EL display panels, and at the same time, it is possible to apply it to panels using thin substrates, and it is possible to reduce the thickness of organic EL display panels. Is.

[Simple explanation of drawings]

[Figure 1]

Structural sectional view of the organic EL display panel according to the first embodiment of the present invention. [Figure 2]

A process sectional view showing a method for manufacturing an organic EL display panel according to the first embodiment of the present invention. [Fig. 3]

A process sectional view showing a method for manufacturing an organic EL display panel according to the first embodiment of the present invention. [Fig. 4]

Structural sectional view of the organic EL display panel according to the second embodiment of the present invention. [Fig. 5]

A process sectional view showing a method for manufacturing an organic EL display panel according to a second embodiment of the present invention. [Fig. 6]

A process sectional view showing a method for manufacturing an organic EL display panel according to a second embodiment of the present invention. [Fig. 7]

Structural sectional view of an organic EL display panel which is a conventional example of the present invention. [Fig. 8]

A graph showing the relationship between the panel surface temperature T2 and the mounting temperature T1 and the distance L from the mounting part. [Explanation of symbols]

1 Organic EL panel 2 board 3 pixel area 4 Organic EL element 5 Connection electrode 6 Flexible wiring board 7 Wiring electrode 8 Insulating photocurable resin 9 Conductive particles 10 Light irradiation 11 Sealing cap 12 Alignment 13 Pressurizing jig 14 Pressurization 15 Semiconductor chip 16 Protruding electrode