JP2002151250A - Plane luminous panel and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable to connect a luminous part consisting of a luminous layer and a lower and upper opposing electrodes and a drive circuit for driving this luminous part in a short wiring route, to secure a large enough drive current in case of high-density pixels, and to achieve a more compact total size, with a plane luminous panel with a luminous layer made of organic EL materials integrally formed on one side of a multi-layer substrate. SOLUTION: A connecting pad for electrode connection is formed on a luminous face of a luminous layer facing outside, and another connecting pad for mounting of drive elements are formed on the other face. The panel is provided with a multi-layer substrate (50) with this so-to-speak double-faced connecting pad connected in an inner circuit layer, a lower opposing electrode (58) formed on one face of the multi-layer substrate and connected to one side of the connecting pad for electrode connection, a luminous layer (62) formed on it made of organic EL materials, a transparent upper opposing electrode (64) formed on the luminous layer and connected to the other side of the connecting pad for electrode connection, and drive elements (60) mounted on the other face of the multi-layer substrate for enabling the luminous layer to emit light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat light-emitting panel using an organic electroluminescent material as a light-emitting layer, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Electroluminescence (EL) that emits light when an electric field is applied is known. A panel (ELP) utilizing this phenomenon is used as a backlight of a monochrome liquid crystal or the like because it emits surface light. In particular, the development of organic EL materials has recently increased the possibility of practical use as a color display panel. In this case, the image is displayed in color by dividing the display screen into a large number of pixels arranged in a matrix and controlling light emission for each of the three color pixels.

FIGS. 5 and 6 are cross-sectional views showing the structure of a conventional flat light-emitting panel using this organic EL material as a light-emitting body. In FIG. 5, reference numeral 10 denotes a transparent glass plate. An ITO film 12 is formed on one surface of the glass plate 10. This ITO film 12 is made of In-Tin-Oxide.
(Indium tin oxide) film, which becomes a transparent lower counter electrode. A light emitting layer 14 made of an organic EL material is formed on the ITO film 12. This light emitting layer 14
May be a thick film formed by a coating method or a screen printing method, or may be a thin film formed by a vacuum evaporation method or a sputtering method.

An upper counter electrode 16 is formed on the light emitting layer 14. The lower counter electrode 12 and the upper counter electrode 16 are guided around the glass plate 10. It is known that the life of the organic EL material that becomes the light emitting layer 14 is greatly affected by moisture. That is, when moisture is contained, the moisture evaporates and expands due to a temperature rise due to energizing operation, and the organic E
This is because the L material, the electrode, and the insulating layer are separated. For this reason, the light emitting layer 14 is hermetically sealed with a protective cap 18, and a desiccant 20 is fixed on the inner surface of the protective cap 18 to form the light emitting layer 14.
Has been dried.

Reference numeral 22 denotes a rigid printed board on which a semiconductor component 24 is mounted. Semiconductor parts 24
Is an integrated circuit that constitutes a drive circuit for controlling light emission of the light emitting layer 14 and has, for example, a gull-wing type lead. The wiring pattern formed on the printed board 22 is guided to one side of the printed board 22. This printed board 22
Are connected to the lower and upper opposed electrodes 12 and 16 on the glass plate 10 side by a flexible cable (FPC) 26.

In the display panel shown in FIG. 6, a flexible printed circuit board 2 is used instead of the rigid printed board 22 shown in FIG.
8 is different from that of FIG. Therefore, the same portions are denoted by the same reference characters and description thereof will not be repeated. . The flexible substrate 28 has a semiconductor chip (bare chip) 3
0 was flip-chip mounted. Then, the flexible substrate 28 is formed on a lower counter electrode (IT) formed on the glass substrate 10.
O film) 12 and the upper counter electrode 16. Gold bumps are formed on the electrodes of the semiconductor chip 30, and these gold bumps are bonded to pads provided on the flexible substrate 28.

[0007]

As described above, in the conventional flat light emitting panel using the organic EL element, the glass substrate 10
A lower opposing electrode 12, a light emitting layer 14, and an upper opposing electrode 16 are formed on the printed circuit board 2 separate from the glass substrate 10.
2, a semiconductor component 24 and a semiconductor chip 30 are mounted on a flexible substrate 28 and these substrates 22 and 28 are connected to the electrodes 12 and 16 on the glass substrate 10 side.

Therefore, the glass substrate 10 and the printed circuit board 2
Since the second or flexible substrate 28 is connected, the wiring path becomes longer. In particular, when performing color display including a large number of pixels with this flat light-emitting panel, it is necessary to increase the density of the pixels in order to improve the image quality. Considering the length of the path, it is difficult to ensure a sufficiently large allowable current. This makes it difficult to increase the density of pixels.

The printed circuit board 2 is separate from the glass substrate 10.
There is also a problem that the entire light-emitting panel becomes large due to the connection of the light emitting panel 2 and the flexible substrate 28.

The present invention has been made in view of such circumstances, and connects a light-emitting unit including a light-emitting layer and a lower / upper counter electrode to a drive circuit for driving the light-emitting unit via a short wiring path. It is a first object of the present invention to provide a flat light-emitting panel which is capable of ensuring a sufficiently large driving current even when the density of pixels is increased, and which is suitable for miniaturization of the whole. A second object of the present invention is to provide a method for manufacturing this flat light emitting panel.

[0011]

According to the present invention, a first object is a flat light-emitting panel in which a light-emitting layer made of an organic EL material is integrally formed on one surface of a multi-layer substrate. A connection board for electrode connection is formed outside the light emitting layer, a connection pad for mounting a driving element is formed on the other surface, and a connection between the connection pads on both sides of the multi-layer substrate is formed by an inner layer circuit. A lower counter electrode formed on one surface of the multilayer substrate and connected to a part of the connection pads for electrode connection; a light emitting layer formed of an organic EL material formed thereon; and a light emitting layer formed on the light emitting layer A transparent upper counter electrode connected to another connection pad for the electrode connection, and a driving element mounted on the other surface of the multilayer substrate for causing the light emitting layer to emit light, By the flat light-emitting panel, It is made.

Since the multilayer substrate is used as described above, a complicated electric circuit network can be formed on the multilayer substrate itself. Since the multilayer substrate is also used as a support for the light emitting layer, the wiring path is significantly reduced. It can be shortened and downsized.

[0013] The entire flat light emitting panel is preferably hermetically sealed with a sealing material. The reason is that the life of the light emitting layer is significantly reduced by moisture, and the life can be extended by hermetic sealing. Therefore, by enclosing a desiccant in the sealing material, the removal of moisture inside can be ensured, which is more suitable for improving the life.

[0014] The sealing material can be formed by a transparent glass plate whose part is bonded to the light emitting layer via a spacer. The glass plate may be adhered to the entire surface of the light emitting layer with a transparent adhesive, but the periphery of the glass plate may be adhered to the multilayer substrate outside the light emitting layer to form a gap between the glass plate and the light emitting layer. Good.

The multilayer substrate is most preferably a low temperature co-fired multilayer ceramic plate (Low Temperature Co-Fireable Ceramics, LTCC). This multilayer LTCC substrate has a low firing temperature (approximately 1000 ° C. or less), and can be significantly reduced in size by forming passive elements such as resistors, capacitors, and inductors inside the ceramic substrate. Therefore, it is suitable for high-density mounting (flip-chip mounting) using a semiconductor bare chip. Further, since the LTCC substrate has a small relative dielectric constant, a delay of a signal passing through the wiring pattern formed here becomes small, and the LTCC substrate is suitable for a high-speed driving circuit.

The multi-layer substrate is preferably coated with a low-melting glass or another oxide-based inorganic substance as a base for the light-emitting layer. In general, since the LTCC substrate or the like is a sintered body of a glass-based material, the surface becomes microscopically uneven due to microscopic unevenness, which affects the image display properties of the self-emitting organic EL material. That is, by this coating process, it is possible to suppress a variation in display performance for each pixel and improve image quality.

The surface of the multilayer substrate on which the driving elements are mounted (the mounting surface of the driving elements) is preferably covered with a resin after the mounting of the elements. This resin coating treatment is for protecting the driving element so as not to be affected by the subsequent various treatment steps (vacuum / wet treatment, etc.). In particular, when a semiconductor element is connected to a multilayer substrate by wire bonding, the surface of the multilayer substrate (driving element mounting surface) is covered with an epoxy-based material so as to cover bonding wires and the like in order to facilitate handling in a later process. Or coating with a silicone resin.

The driving element may be not only an active element such as a semiconductor circuit element but also a passive element such as a resistor and a capacitor. The semiconductor circuit element may be a semiconductor element sealed in a package, or may be a bare chip. In the case of a bare chip, a protruding electrode such as a gold bump is provided on the electrode and directly connected to an electrode of a multilayer substrate (flip chip mounting).

According to the present invention, a second object is a method of manufacturing a flat light-emitting panel in which a light-emitting layer made of an organic EL material is integrally formed on one surface of a multi-layer substrate. A connection board for connecting the electrode of the light emitting layer and a connection pad for mounting the driving element are formed, respectively, and the connection pads on both sides prepare a multilayer board connected by an inner layer circuit; (b) electrode connection of the multilayer board Forming a coating layer made of an inorganic material on the surface on which the connection pads for the light emitting layer are formed, and smoothing the surface; (c) connecting to some of the connection pads for electrode connection of the light emitting layer on the coating layer; (D) mounting the driving element on the surface of the multilayer substrate on which the connection pad for mounting the driving element is formed; (e) forming the light emitting layer made of the organic EL material on the coating layer. Form; f) Forming a transparent upper counter electrode connected to the other connection pad for electrode connection on the light emitting layer; a planar light emission comprising the above steps (a) to (f). Panel manufacturing method.

In this case, if a low-temperature processing method that does not require heating the multilayer substrate can be used to mount the driving element on the multilayer substrate, the steps (d) and (e) may be reversed. That is, since the organic EL material cannot be heated, when a method that does not require heating the substrate after forming the light-emitting layer, for example, an ultrasonic bonding method or an electric resistance soldering method is used, the light emission of the organic EL material is used. After forming the layer, the driving element may be mounted.

[0021]

FIG. 1 is a cross-sectional view of one embodiment of the present invention, FIG. 2 is a cross-sectional view showing an embodiment in which the structure shown in FIG. 1 is hermetically sealed in a sealing case, and FIG. It is a flowchart of.

In FIGS. 1 and 2, reference numeral 50 denotes a multilayer substrate, which is a low-temperature co-fired ceramic substrate (multilayer LTCC substrate).
It is. On the LTCC substrate 50, a circuit pattern is formed in a multilayer structure, and one surface thereof (lower surface, light emitting layer forming surface)
A surface via (Su) for connecting to lower and upper counter electrodes 58 and 64 described later is provided at a position outside the light emitting layer 62 described later.
A connection pad 52 such as rface Buried Via-Hole (SVH) is formed. On the other surface (upper surface, driving element mounting surface) of the LTCC substrate 50, connection pads (not shown) for driving elements described later are formed.

The LTCC substrate 50 is prepared (FIG. 3, step S100), and a coating layer 54 of an inorganic substance is formed on the lower surface (the surface on which the light emitting layer is formed) (step S100).
102). The inorganic substance used here is, for example, low-melting glass or another oxide-based inorganic substance. The coating layer 54 may be selectively formed only on the region where the light emitting layer 62 is formed, or may be formed on the entire surface. In the case of forming the entire surface, a via hole is made by irradiating a laser beam from above the coating layer 54 to the position of the connection pad 52. That is, the laser via hole 56 (see FIG. 3) is formed (Step S104).

After the formation of the coating layer 54 or the formation of the laser via hole 56, the coating layer 54
The lower opposing electrode 58 is formed on the substrate (step S10).
6). The lower counter electrode 58 can be formed by forming a metal film (for example, an aluminum film) on the entire lower surface by a normal evaporation method or a sputtering method, and then removing unnecessary portions by etching by a photolithography method. As a result, the circuit pattern of the lower counter electrode 58 is connected to the connection pad 52.

Next, the other surface of the LTCC substrate 50 (the upper surface,
The driving element 60 is mounted on the driving element mounting surface (Step S108). The driving element 60 is an active element such as a semiconductor circuit element or a passive element such as a resistor or a capacitor.
In the case of a semiconductor circuit element, an electrode on which a gold bump of a semiconductor bare chip is formed is directly connected to a connection pad formed on the LTCC substrate 50. That is, it is preferable to use a flip chip connection by an ultrasonic method, a thermocompression bonding method, a pressure welding method, or the like. Passive elements such as resistors and capacitors may be soldered by a known surface mounting method.

After the mounting of the driving element 60, it is desirable to apply an epoxy resin or a silicone resin to protect the driving element 60 from the processing in a later step (step S).
110). This protection processing (S110) may be omitted in some cases.

Next, the light emitting layer 62 is formed on the lower surface of the LTCC substrate 50.
Is formed (step S112). This light emitting layer 62
In the case of a powder panel (dispersion type panel), a material obtained by dispersing an organic EL material in a synthetic resin or a low-melting glass powder may be applied by a coating method or a screen printing method as in the case of the thick film integrated circuit. In the case of a thin film panel, a thin light emitting layer 62 is formed on the lower surface of the LTCC substrate 50 by vacuum evaporation and sputtering. In step S110, when the light emitting layer 62 is formed from this thin film, the LTCC substrate 5
In order to protect the drive element 60 from these vacuum / wet atmospheres, considering that 0 can be put in a vacuum atmosphere or in a wet atmosphere for forming color pixels by photolithography, It is.

After forming the light emitting layer 62, an upper counter electrode 64 is formed on the light emitting layer 62 (step S1).
14). The upper counter electrode 64 is a transparent electrode,
It is formed of a TO film. The upper counter electrode 64 is connected to a position different from the connection pad 52 (FIGS. 1 and 2) of the lower counter electrode 58, for example, to a connection pad (not shown) formed on a side orthogonal to the side on which the connection pad 52 is provided. Is done.

The thus formed flat light emitting panel 66 shown in FIG. 1 is hermetically sealed as shown in FIG. 2 (step S116). The sealing material 68 used here is formed of a housing 72 in which a transparent glass plate 70 is fitted on the lower surface. Here, the glass plate 70 is the light emitting layer 6 of the LTCC substrate 50.
2 with a spacer 74 interposed therebetween. The adhesive used here is transparent. The housing 72 contains a desiccant 7.
6 is enclosed. The desiccant 76 may be fixed to the driving element 60.

[0030]

FIG. 4 is a flowchart of a manufacturing process according to another embodiment. In this embodiment, steps S108 and S110 in the step shown in FIG. 3 are reversed from step S112. That is, after the lower counter electrode 58 is formed (Step S106), the light emitting layer 62 is formed (Step S108A), and the driving element 60 is mounted (Step S110A). The driving element 60 is protected by coating with a protective film as necessary (step S112A).

This embodiment can be used when it is not necessary to heat the LTCC substrate 50 when mounting the driving element 60. That is, since the organic EL material of the light emitting layer 62 has a low heat-resistant temperature, it is assumed that no heat treatment is performed when the driving element 60 is mounted. For example, ultrasonic soldering,
When the driving element 60 is mounted by an electric resistance soldering method or the like, the method shown in FIG. 4 can be used.

[0032]

According to the first aspect of the present invention, the light emitting layer and the lower and upper counter electrodes are formed on one surface of the multilayer substrate, and the driving element is mounted on the other surface. The wiring path to the element can be shortened, and the driving current can be sufficiently secured even when the density of pixels is increased.
Further, the size of the entire panel can be reduced.

If the panel is hermetically sealed with a sealing material, the light emitting layer can be protected from moisture, and the life of the panel can be extended (claim 2). If a desiccant is placed inside the sealing material, the removal of moisture is further ensured (claim 3). The sealing material can be formed by a housing having a transparent glass plate adhered to the light emitting layer via a spacer (claim 4).

If the multi-layer substrate is a low-temperature co-fired multi-layer ceramic plate, the coefficient of thermal expansion is small, so that it is convenient when a semiconductor chip as a driving element is flip-chip mounted. If an inorganic substance coating layer is formed as a base of the light emitting layer, the image display property of the light emitting layer is improved (claim 6). If the mounting surface of this element is covered with a resin after mounting the driving element, the element and the like can be protected from the subsequent processing (claim 7). If the driving element is a semiconductor pair chip, and this is flip-chip mounted, the overall size can be further reduced (claim 8).

According to the invention of claims 9 to 11, claim 1
To 8 are obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the same airtightly sealed state.

FIG. 3 is a flowchart of a manufacturing process.

FIG. 4 is a flowchart showing another embodiment of the manufacturing process.

FIG. 5 is a sectional view showing a conventional flat light emitting panel.

FIG. 6 is a cross-sectional view showing a conventional flat light-emitting panel.

[Explanation of symbols]

 Reference Signs List 50 multilayer substrate (multilayer LTCC substrate) 54 coating layer 58 lower opposing electrode 60 driving element (semiconductor chip) 62 light emitting layer (organic EL material) 64 upper opposing electrode (transparent electrode) 66 flat light emitting panel 68 sealing material 70 transparent glass Plate 72 housing 74 spacer 76 desiccant

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) H05B 33/10 H05B 33/10 33/14 33/14 A (72) Inventor Satoshi Arano Nishi, Minato-ku, Tokyo 3-20-1, Shimbashi Nippon Avionics Co., Ltd. (72) Naoto Nakatani 3-20-1, Nishi-Shimbashi, Minato-ku, Tokyo F-term within Nippon Avionics Co., Ltd. 3K007 AB05 AB18 BA06 BB01 BB05 CA02 CB01 DA01 DB03 EA01 EB00 EC01 FA02 5C094 AA07 AA13 AA15 AA25 AA38 AA43 BA27 CA19 DA09 DA12 DA13 DB01 DB02 EA05 EA10 EB10 FA02 FB12 FB15 GB10 5G435 AA03 AA13 AA16 AA17 AA18 BB05 CC09 EE05 BB05 CC09 EE

Claims (11)

[Claims] 1. A flat light-emitting panel in which a light-emitting layer made of an organic EL material is integrally formed on one surface of a multilayer substrate, and a connection for electrode connection is formed on a surface on which the light-emitting layer is formed, outside the light-emitting layer. Pads are formed, connection pads for mounting driving elements are formed on the other surface, and connection pads on both surfaces are connected by an inner layer circuit; and the electrode is formed on one surface of the multilayer substrate. A lower opposing electrode connected to some connection pads for connection, a light emitting layer formed of an organic EL material formed thereon, and another connection pad formed on the light emitting layer and connected to the electrode. A flat light-emitting panel comprising: a connected transparent upper counter electrode; and a driving element mounted on the other surface of the multilayer substrate to emit light from the light-emitting layer. 2. The flat light-emitting panel according to claim 1, wherein the whole is hermetically sealed with a sealing material. 3. The flat light emitting panel according to claim 2, wherein a desiccant is contained in the sealing material. 4. The flat light-emitting panel according to claim 1, wherein the sealing material is formed of a housing having a transparent glass plate adhered to the light-emitting layer via a spacer. 5. The flat light-emitting panel according to claim 1, wherein the multilayer substrate is a low-temperature co-fired multilayer ceramic plate. 6. The flat light-emitting panel according to claim 1, wherein a coating layer of an inorganic substance serving as a base of the light-emitting layer is formed on one surface of the multilayer substrate. 7. The flat light-emitting panel according to claim 1, wherein a surface on which the driving element is mounted is covered with a resin. 8. The driving element is a semiconductor bare chip flip-chip mounted on a surface of a multilayer substrate.
Any of the flat light emitting panels. 9. A method of manufacturing a flat light-emitting panel in which a light-emitting layer made of an organic EL material is integrally formed on one surface of a multilayer substrate, comprising: (a) connection pads for connecting electrodes of the light-emitting layer on different surfaces. And a connection board for mounting the drive element is formed, and a connection board on both sides of the connection board is formed, and a connection board on the both sides is prepared by a multilayer board. Forming a coating layer made of an inorganic material to smooth the surface; (c) forming a lower counter electrode connected to a part of connection pads for electrode connection of the light emitting layer on the coating layer; d) mounting the driving element on the surface of the multilayer substrate on which the connection pads for mounting the driving element are formed; (e) forming a light emitting layer made of an organic EL material on the coating layer; (f) this light emitting layer Above the Forming a transparent upper counter electrode connected to another connection pad for electrode connection; a method for manufacturing a flat light-emitting panel, comprising the above steps (a) to (f). 10. A flat light-emitting panel having the following steps (d-1) and (d-1): a protection process for protecting a driving element is performed after step (d) of claim 9. Method. 11. A method for manufacturing a flat light-emitting panel in which a light-emitting layer made of an organic EL material is integrally formed on one surface of a multilayer substrate, wherein (A) connection pads for connecting electrodes of the light-emitting layer on different surfaces. And a connection board for mounting a driving element is formed, respectively, and a connection board on both sides of the connection board is prepared. A multilayer board connected by an inner layer circuit is prepared. (B) On a face of the multilayer board on which connection pads for electrode connection are formed. Forming a coating layer made of an inorganic material to smooth the surface; (C) forming a lower counter electrode connected to some connection pads for electrode connection of the light emitting layer on the coating layer; D) forming a light-emitting layer made of an organic EL material on the coating layer; (E) mounting the driving element on a surface of the multilayer substrate on which the connection pad for mounting the driving element is formed; This luminescence Forming a transparent upper counter electrode on the layer; a method for manufacturing a flat light-emitting panel, comprising the above steps (A) to (F).