JPH06325868A - Thin film electroluminescent panel - Google Patents

Abstract

PURPOSE:To provide a sealed base board for protecting an EL element formed on a glass base board from the outside air so that the sealed base board is unlikely to go in breakage as much as the glass base board and also suppress the material cost and processing cost. CONSTITUTION:A sealed base board is formed from a composite material with metal layers 22 laminated on at least either surface of an organic resin 22. This allows suppression of the costs, facilitates the processing, prevents breakage because of flexibility of the organic resin. and gives a sealing effect with the low moisture permeability of the metal. The electromagnetic waves emitted from EL element can be shielded simply by grounding the metal layer 22 of sealed base board.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film EL panel in which an AC electric field type thin film electroluminescence (EL) element is sealed in order to protect it from the influence of outside air.

[0002]

2. Description of the Related Art A thin film EL that exhibits EL when an electric field is applied.
The element is attracting attention as a panel for a thin display device because it can emit high-luminance light, have high resolution, and have a large display capacity. A general thin film EL panel is constructed as shown in FIG. 2, FIG. 3 or FIG. In the EL panel whose data line side cross-sectional structure is shown in FIG. 2, an EL element having a thin film laminated structure is formed on a transparent glass substrate. This consists of InO ₂ , SnO ₂ or I on a transparent glass substrate 10.
A large number of parallel strip-shaped transparent lower electrodes 1 made of TO (In ₂ O ₃ .SnO ₂ ) are provided, and Al is formed on the transparent electrodes 1.
_A first dielectric layer (first insulating layer) 2 made of any one of ₂ O ₃ , Si ₃ N ₄ , SiO ₂ , TaO ₅ , TiO _2, etc. is formed by a sputtering method, an electron beam evaporation method or an atomic layer epitaxial growth method ( Hereinafter, abbreviated as ALE method) or the like. Next, a ZnS light emitting layer 3 formed by a sputtering method, an electron beam evaporation method, an ALE method or the like is formed on the first insulating layer, and then the second dielectric layer 4 is formed on the first dielectric layer 2.
It is formed by the same material and forming means. Next, an electrode layer made of Al or the like is formed by a sputtering method or an electron beam evaporation method, and a stripe pattern is formed by a photolithography method so as to be orthogonal to the transparent lower electrode 1 to form a back electrode 5. In this EL panel, the portion of the EL light emitting layer 3 corresponding to the intersection of the transparent electrode 2 and the back electrode 5 is used as each pixel, and the display light emitted by EL by applying a predetermined voltage from the AC power supply 30 is transparent glass. It is designed to be taken out from the substrate 10 side.

However, in the state where the upper surface is left open as described above, there is a possibility that practical display cannot be performed due to moisture and contaminants in the outside air. Therefore, it is necessary to cover the upper surface with the cover, but it is simply covered. However, since the first and second dielectric layers 2 and 4 sandwiching the light emitting layer 3 contain many pinholes and microcracks generated during the stacking, Moisture easily enters into the light emitting layer 3 from the space inside the cover, which causes heat generation due to EL light emission loss, delamination of the layer, and the like, resulting in deterioration of EL element characteristics.

FIG. 3 and FIG. 4 show an EL panel sealing structure which has been proposed and put into practical use as a countermeasure. In FIG. 3, a sealing material 6 such as an epoxy resin having a low moisture permeability is applied on the transparent electrode 2 on the glass substrate 10 by screen printing or the like, and the peripheral portion of the sealing glass substrate is brought into contact with the sealing material 6, followed by heat curing. To adhere. The injection port 7 is formed in the space 12 created by this.
The liquid silicone oil is injected and filled from above, and the injection port 7 is sealed with an adhesive 8 using a cover glass plate 13. In this EL panel, the space 12 is formed between the EL element and the flat sealing glass substrate 11. In this case, if the thickness of the sealing material 6 is increased, the permeation area of moisture in the outside air increases. , Because it is easy for moisture to enter,
Limited to 12 heights. Figure 4 improves this point,
12 is formed by the sealing glass substrate 11, and the space 12
You can freely choose the height of. Since the sealing glass substrate 11 and the surface of the transparent electrode 1 can be bonded with a thin sealing material 6,
The permeation area of moisture in the outside air is reduced and the sealing performance is improved.

On the other hand, when the thin film AC EL panel is displayed by AC driving, it is inevitable to radiate electromagnetic waves to the outside. As measures against this, JP-A-63-254697 and JP-A-
As disclosed in Japanese Patent Laid-Open No. 63-254698, a conductive film, a conductive sheet, or the like is installed on a front surface, a rear surface, or both of the EL display panel in a place other than the EL panel display surface, and an AC for driving the EL panel is installed. It was connected to the ground terminal of the power supply and shielded the electromagnetic waves emitted from the EL panel. FIG. 5 shows an EL panel disclosed in Japanese Patent Application Laid-Open No. 63-170892. In this case, the EL element portion is covered with a resin sealing layer 41.
A metal plate 42 is laminated on the back surface side of and is grounded. The metal plate 42 absorbs the electromagnetic wave emitted from the EL element.

[0006]

Problems to be Solved by the Invention E shown in FIGS.
The encapsulating glass substrate 11 of the L panel has the drawbacks of high cost and easy breakage. However, there are the following problems when trying to use other low-cost sealing substrates. That is, the thin film E
In order to remove defects such as pistons and micro-cracks that occur when the L element is laminated, it is possible to gradually raise the voltage from zero volt to the luminescent display voltage by the AC power supply at the initial energization and crush it so that the defective part is minimized. Be seen. Further, since the laminated film is an unstable film after being formed, it is necessary to stabilize it by aging. At this time, in order to shorten the aging time, a voltage having a frequency higher than the actually used display frequency is applied. In this case, the temperature of the EL element portion also rises to about several tens of degrees Celsius. Further, when a thermosetting epoxy resin is used for the sealing material 6, it is necessary to withstand a curing temperature of 80 to 180 ° C. In addition, the sealing substrate is required to have low moisture permeability in order to cover the EL element with a large area, and to have good adhesiveness in order to seal the EL element by adhesion with the substrate. Further, in the structure shown in FIG. 5, it is difficult to reduce the moisture permeability because the resin sealing layer 41 must be used only to prevent the permeation of moisture into the light emitting portion.

The object of the present invention is to solve the above problems, to prevent breakage, to have good heat resistance and adhesiveness, and to have low moisture permeability,
Furthermore, it is possible to shield electromagnetic waves, and thin film EL using a sealing substrate with low material cost and processing cost.
To provide a panel.

[0008]

In order to achieve the above object, the present invention provides a laminated body in which a light emitting layer is sandwiched by electrode layers with a dielectric layer on an insulating and transparent panel substrate. Prepare,
The end of the sealing substrate that covers the non-panel substrate side of the laminate is joined to the panel substrate via a sealing material, and the liquid material is injected into the space created on the laminate by the sealing substrate and the panel substrate. In the EL panel, the sealing substrate is made of a composite material in which a metal and an organic resin are laminated. It is effective that the liquid material injection port opened in the sealing substrate is closed by a closing plate made of the same material as the sealing substrate. It is desirable that the metal layer of the sealing substrate is provided at least on the side opposite to the panel substrate, but it may be provided on both sides of the organic resin. It is also effective that the metal layer of the sealing substrate is grounded.
In addition, the metal of the sealing substrate is aluminum,
It is effective that the organic resin is polyethylene or polypropylene.

[0009]

[Function] Since the sealing substrate is made of a composite material of a metal and an organic resin, the strength is sufficient if the thickness of the organic resin is a certain amount or more, and there is no fear of breakage like glass, and it is better than a glass substrate. Low cost and good workability. Since only organic resin has high moisture permeability, water may enter the meat portion, but by laminating a metal having low moisture permeability, sealing performance is improved. Further, the adhesiveness with the sealing material is good whether it is an organic resin or a metal, and there is no problem in the adhesive strength. In addition, since the organic resin is flexible and absorbs the shrinkage of the sealing material due to heat curing or ultraviolet curing, damage due to shrinkage stress does not occur.

If the metal layer is grounded, electromagnetic waves are shielded by the sealing substrate covering the entire surface of the EL element, so that a high shielding effect can be obtained without newly forming an electromagnetic wave shield structure.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to the drawings in which the same parts as those in FIGS. 2, 3, 4 and 5 are designated by the same reference numerals. In the first embodiment shown in FIG. 1, ITO (In ₂ O ₃ .SnO ₂ ) is electron beam evaporated or sputtered on the entire surface of the substrate 10 and then the parallel striped stripe pattern of the transparent electrode 1 is wetted by photolithography. It is formed by etching processing by etching.

Next, the first dielectric layer 2 is formed in a thickness of about 2000 to 4000Å by a sputtering method using a metal mask so as to have a predetermined area. At this time, the material of the dielectric 2 is Al ₂ O ₃ , Ta ₂ O ₅ , SiO ₂ , Si ₃ N ₄ , Y ₂
One or two kinds of O ₃ and TiO ₂ are selected and used to form a one-layer or two-layer film. Next, the light emitting layer 3 is formed on the first dielectric layer 2 to a thickness of 4000 to 10000Å by a sputtering method, an electron beam evaporation method or an ALE method so as to have a predetermined area by using a metal mask. ZnS is used as the phosphor base material of the light emitting layer and Mn is added as the additive material in the range of 0.4 to 1.6 Wt.
Use pellets or targets prepared by mixing%. After film formation, in a vacuum of 1 × 10 ^-5 Torr, 300 to 700 ℃, 1
Perform heat treatment for ~ 2 hours.

Further, the second dielectric layer 4 is formed on the light emitting layer 3 in a thickness of 2000 to 4000Å so as to have a predetermined area by using a metal mask by a sputtering method. As a material,
Al ₂ O ₃ , Ta ₂ O ₅ , SiO ₂ , Si ₃ as well as the first dielectric layer 2
One or two kinds of N ₄ , Y ₂ O ₃ and TiO ₂ are selected and used to form a one-layer or two-layer film. Then, an Al layer is formed as a back electrode 5 on the second dielectric layer 4 by electron beam evaporation. The back electrode 5 has a two-layer structure as required. In this case, Ni is continuously formed on Al by the same electron beam evaporation. Then, the back electrode 5 is formed by patterning in a stripe shape by photolithography so as to be orthogonal to the transparent electrode.

FIG. 6 is a plan view showing an electrode pattern. In both the transparent electrode 1 and the back electrode 5, terminal electrodes are alternately drawn out from both sides of the electrode, and the pattern pitch is 0.
The electrode width is about 2 to 0.3 mm and the electrode width is about 0.15 to 0.22 mm. The pitch of the terminal electrodes 15 and 55 in the terminal portion is 0.4 to 0.6 mm, and the electrode width is 0.2 to 0.3 mm. This EL panel sealing substrate 20
Consists of an organic resin 21 and a metal layer 22 covering both surfaces thereof,
Thickness is 0.15 / 1.7 / 0.15mm (total thickness 2.0mm) or 0.0.
It is 15 / 0.7 / 0.15mm (total thickness 1.0mm). As the organic resin, use is made of polyethylene, polypropylene or the like having a high heat resistance such as a heat distortion temperature of 80 ° C or higher and a continuous use temperature of 100 ° C or higher. The method for laminating the sealing substrate is to form a metal layer 22 on the surface-treated organic material 21 by a vacuum deposition method or a sputtering method, or to form a metal foil using an adhesive and a surface-treated organic resin and a metal foil. Laminate and laminate. The surface treatment of the organic resin is performed in order to improve the adhesion with the metal. The hole of the inlet 7 is punched in the sealing substrate in advance. As the sealing material 6,
A one-component or two-component thermosetting epoxy resin or an ultraviolet curing epoxy resin is used. In order to control the thickness of the sealing resin, an appropriate amount of glass rod spacers having a diameter of 5 to 50 μm are mixed. This sealing material 6 is applied to the edge of the sealing substrate by screen printing in a width of several mm. Seal material 6
As for the curing method, the thermosetting type is cured in air at 80 to 180 ° C. for 30 minutes to 1 hour and then sealed. The ultraviolet curing type is irradiated with an ultraviolet light source from the glass substrate 10 side at room temperature to cure and seal. Although not shown, the grounding lead is connected to the metal layer 22 on the inner surface, and the end of this lead and the glass substrate are connected.
10 and the ground terminal electrode 16 provided in one of the corners without the signal terminal electrodes 15 and 55 are cured and electrically connected at the same time as the sealing material by a conductive adhesive that is cured at room temperature or thermally cured. The metal layer 22 is grounded by connecting the ground terminal electrode 16 to, for example, the ground portion of the EL panel drive circuit via a lead wire or FPC (flexible printed circuit) using soldering or anisotropic conductive tape. , Becomes an electromagnetic wave shield structure.

Next, the space 12 is filled with liquid silicone oil having a high insulating property through the inlet 7, and the sealing plate 6 is made of the same closing material 9 as the sealing substrate 20.
The same material 8 is used for adhesive sealing. In this structure, the sealing resin 6 is adhesively sealed up to the outer peripheral end surface of the sealing substrate 20 to improve the performance. Bonding with the seal adhesive 6 provides higher bonding strength when bonding the glass substrate and the metal layer than when bonding the glass substrates together as shown in FIGS. 3 and 4, and the composite sealing substrate 20 The difference in thermal expansion coefficient from the glass substrate 1 can be absorbed by the flexibility of the composite sealing substrate.

In the second embodiment shown in FIG. 7, as in the conventional structure of FIG. 4, the space 12 is formed by the sealing substrate 20, and the same composite material plate as that used in FIG. 1 is formed by pressure. Then, it is made into a plate shape, punched out the injection port 7 by punching, and then adhered with a sealing material 6. In this sealing method, the depth of the space for injecting the liquid material can be freely selected, so that the thickness of the sealing material 6 can be reduced. For this reason, the area where moisture in the outside air permeates the resin from the sealed portion can be reduced, and the reliability of the EL element is enhanced. In FIG. 5, the sealing material 6 is adhesively sealed only on the flat surface of the edge portion of the sealing substrate 20, but as described above, sealing the outer peripheral end face of the sealing substrate will further improve the sealing performance. Needless to say.

In the third embodiment shown in FIG. 8, the sealing substrate 20 is used.
The metal layer 22 is provided only on one side. Thickness is Al layer
22 is 0.25 mm, organic resin 21 is 0.70 mm, and the total thickness is 0.95 mm. Then, the organic resin surface adheres to the sealing material 6. In this case, since the metal layer 22 is only on one side, the moisture permeability is slightly higher, but the difference in the coefficient of thermal expansion between the sealing material 6 and the organic resin 21 is small, so the adhesive strength is improved.

The fourth embodiment shown in FIG. 9 is similar to FIG. 7 except that the sealing substrate 20 having the metal layer 22 on only one side is used to form a dish shape. It has the same characteristics as the example. Such a metal layer 22 on one or both sides
The sealing substrate 20 having the moisture permeability of 0.4 to 1.0 g / m ² ·
Water vapor permeability of the glass sealing substrate 11 is 0.417 g / m ^{2 in} 24 hours.
・ It is a level with almost no problem for 24 hours.

As described above, it is obvious that the second to fourth embodiments can easily form an electromagnetic wave shield structure by grounding the metal layer 21. In the fifth embodiment shown in FIG. 10, the metal layer 22 of the sealing substrate 20 is provided only on one side similarly to the third embodiment, but the metal layer 22 is not on the outer surface side but on the inner surface side, and on the glass substrate 10. The lead 17 facilitates connection to the ground terminal electrode 16 of. In this case, the organic resin 21
A material having low moisture permeability, for example, a moisture retaining resin may be used. Similarly, in the sixth embodiment shown in FIG. 11, a metal layer is formed on the inner surface side.
21 is provided, and the sealing substrate 20 is shaped like a dish as in FIGS. 7 and 9.

[0020]

According to the present invention, by using a substrate made of a laminated composite material of an organic resin and a metal, instead of a glass substrate which has been conventionally used as a sealing substrate and which has a high material cost and a high processing cost, an organic compound Coupled with the flexibility of resin and the low moisture permeability of metal, the sealing performance is practically no problem, and a highly reliable thin film EL panel can be obtained by sealing with a low-cost sealing substrate with no risk of damage. It was

Furthermore, by grounding the metal layer of the sealing substrate, it was possible to easily shield the electromagnetic wave radiated from the EL element without newly forming an electromagnetic shield material outside the EL panel.

[Brief description of drawings]

FIG. 1 is a conceptual cross-sectional view of a thin-film EL panel on the side of a data line according to a first embodiment of the present invention.

FIG. 2 is a conceptual side cross-sectional view of a data line of a conventional thin film EL panel.

FIG. 3 is a conceptual cross-sectional view of another conventional thin film EL panel on the side of a data line.

FIG. 4 is a sectional view of the side of a conceptual data line of still another conventional thin film EL panel.

FIG. 5 is a sectional side view of a conceptual data line of a conventional thin film EL panel having an electromagnetic wave shielding function.

FIG. 6 is a plan view showing an electrode pattern of a thin film EL panel according to an example of the present invention.

FIG. 7 is a conceptual data line side cross-sectional view of a thin film EL panel according to a second embodiment of the present invention.

FIG. 8 is a conceptual data line side cross-sectional view of a thin film EL panel according to a third embodiment of the present invention.

FIG. 9 is a conceptual data line side cross-sectional view of a thin film EL panel according to a fourth embodiment of the present invention.

FIG. 10 is a conceptual data line side cross-sectional view of a thin film EL panel according to a fifth embodiment of the present invention.

FIG. 11 is a conceptual data line side cross-sectional view of a thin film EL panel according to a sixth embodiment of the present invention.

[Explanation of reference numerals] 1 transparent electrode 2 first dielectric layer 3 light emitting layer 4 second dielectric layer 5 back electrode 6 sealing material 7 injection port 8 adhesive 9 closure plate 10 glass substrate 12 space portion 20 sealing substrate 21 organic Resin 22 Metal layer 15, 55 Terminal electrode 16 Ground terminal electrode

Claims (8)

[Claims] 1. An end of a sealing substrate, which comprises a laminated body having a light emitting layer sandwiched between electrode layers via a dielectric layer on an insulative and transparent panel substrate, and covering the non-panel substrate side of the laminated body. The part is joined to the panel substrate through the sealing material, and the liquid material is injected into the space generated on the laminate by the sealing substrate and the panel substrate. In the sealing substrate, the metal and the organic resin are laminated. A thin-film electroluminescent panel characterized by being made of a composite material. 2. The liquid material injection port opened in the sealing substrate is closed by a closing plate made of the same material as the sealing substrate.
A thin film electroluminescent panel as described. 3. The thin film electroluminescence panel according to claim 1, wherein the metal layer of the sealing substrate is provided at least on the side opposite to the panel substrate. 4. The thin film electroluminescent panel according to claim 1, wherein the metal layer of the sealing substrate is provided on both surfaces of the organic resin. 5. The thin film electroluminescence panel according to claim 1, wherein the metal layer of the sealing substrate is grounded. 6. The thin film electroluminescent panel according to claim 1, wherein the metal of the sealing substrate is aluminum. 7. The thin film electroluminescent panel according to claim 1, wherein the organic resin of the sealing substrate is polyethylene. 8. The thin film electroluminescent panel according to claim 1, wherein the organic resin of the sealing substrate is polypropylene.