JPH0419554B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD This invention relates to a thin-film EL panel, and particularly to a structure in which flexible leads are soldered to terminal portions of transparent electrodes and back electrodes arranged in a matrix. Conventional technology Conventionally, for AC-operated thin-film EL devices, a high electric field (about 10 ⁶ V/cm) is regularly applied to the light emitting layer, and in order to improve dielectric strength, luminous efficiency, stability of operation, etc. ~1.0wt% Mn (or Cu,
A three-layer structure ZnS:Mn (or Zn Se:Mn) in which a semiconductor light-emitting layer such as ZnS or ZnSe doped with Al, Br, etc. is sandwiched with a dielectric thin film such as Y ₂ O ₃ or Ta ₂ O ₅ .
EL devices have been developed, and improvements in various light-emitting characteristics have been confirmed. This thin film EL element emits high-intensity light when an alternating current electric field of several KHz is applied, and has a long lifespan. FIG. 7 shows the basic structure of a Zn S:Mn thin film EL device as an example of a thin film EL device. To specifically explain the structure of the thin film EL element based on FIG. 7, the hard and transparent front glass substrate 1
A transparent electrode 2 made of In ₂ O ₃ , SnO ₂ or the like is placed on top, and a first layer made of Y ₂ O ₃ , Ta ₂ O ₅ , Al ₂ O ₃ , Si ₃ N ₄ , SiO ₂ etc. is layered on top of the transparent electrode 2 . The dielectric layer 3 is formed by sputtering, electron beam evaporation, or the like. A ZnS luminescent layer 4 is formed on the first dielectric layer 3 by electron beam evaporation of ZnS:Mn sintered pellets. At this time, Zn for deposition
S:Mn sintered pellets are used in which the concentration of Mn, which is an active substance, is set to suit the purpose. A second dielectric layer 5 made of the same material as the first dielectric layer 3 is laminated on the ZnS light emitting layer 4, and a back electrode 6 made of Al or the like is further deposited thereon. The transparent electrode 2 and the back electrode 6 are formed into a strip shape as shown in FIG. 8, and a matrix electrode structure is adopted in which a plurality of electrodes are arranged perpendicularly to each other. The intersection position 7 (hatched area in the figure) corresponds to one pixel on the panel. The transparent electrode 2 and the back electrode 6 are connected to the AC power supply 1 via switches 8 and 9, respectively.
0, and the thin film EL element is driven. In the above configuration, when the switches 8 and 8 are closed and an AC voltage is applied between the electrodes 2 and 6, the above AC voltage will be induced between the dielectric layers 3 and 5 on both sides of the ZnS light emitting layer 4. , therefore the ZnS luminescent layer 4
Electrons that are excited in the conductor by the electric field generated within the conductor and accelerated to obtain sufficient energy directly excite the Mn luminescent center, and when the excited Mn luminescent center returns to the ground state, it becomes orange-yellow. emits light. In other words, electrons accelerated by a high electric field enter the Zn site, which is the luminescence center in the ZnS luminescent layer 4.
When the electron of Mn atom is excited and falls to the ground state,
It emits strong light in a wide wavelength range with a peak of approximately 5850 Å. The thin film EL element having the structure described above can be used as a flat thin display device that takes advantage of the space factor to display characters, symbols, still images, moving images, etc. It can be used as a means of displaying images, etc., and is very effective. However, the dielectric layer of a thin film EL element contains many pinholes and microcracks generated during the manufacturing process, and moisture, etc. enters the ZnS light emitting layer 4 through these defects, resulting in heat generation due to EL emission loss, This may lead to delamination, deterioration of device characteristics, etc. In order to solve the above problem, as shown in Fig. 9, we investigated the expansion of the microscopic thermal damage area caused by the breakdown caused by pinholes, etc., which occur during energization. A thin-film EL panel 11 is known that prevents and fixes moisture in an atmospheric environment, has a heat dissipation effect, and is effective against vibration and deflection. This thin film EL panel 11 will be explained based on FIG. 9. Note that the left half of FIG. 9 shows a cross-sectional view in a direction parallel to the transparent electrode 2, and the right half shows a cross-sectional view in a direction perpendicular to the transparent electrode 2. Reference numeral 1 denotes a glass substrate, on which transparent electrodes 2 are arranged parallel to each other in a strip shape at a constant pitch interval,
A thin film EL element 12 is constructed by laminating a dielectric layer 3, a light emitting layer 4, a second dielectric layer 5, and a back electrode 6. A dish-shaped cover glass 13 is superimposed on the glass substrate 1 so as to accommodate the thin film EL element 12, and the thin film EL element 12 is built into the internal gap thereof. The joint between the glass substrate 1 and the cover glass 13 is bonded with an adhesive 1 such as photocurable resin (Photopond).
4 is sealed. That is, the glass substrate 1 and the cover glass 13 constitute an envelope 15 for the thin film EL element 12. And inside the envelope 15 there is a thin film.
In addition to the built-in EL element 12, silicone oil,
An insulating protective fluid 16 such as vacuum grease for protecting the thin film EL element 12 is filled and sealed. The conditions required for the insulating protective fluid 16 include permeability into pinholes, high dielectric strength, heat resistance,
It is desirable that the material has excellent moisture resistance, does not react with the constituent films of the thin film EL element 12, and has a low vapor pressure and coefficient of thermal expansion, but it is particularly desirable that it has good permeability into pinholes, has a somewhat high dielectric strength, and is a thin film. EL
It is required that it does not react with the element constituent films. This insulating protective fluid 16 is injected from an injection hole 17 provided in the cover glass 13, and this injection hole 17 is sealed with a resin 18 (Japanese Patent Application Laid-Open No.
122990), and a glass lid plate is bonded and sealed with an adhesive (Japanese Patent Application Laid-open No. 127790/1983). By the way, when connecting an external drive circuit to the transparent electrode 2 or the back electrode 6, it is not possible to solder the flexible leads directly onto these electrodes, so some parts may overlap with the ends of the transparent electrode 2 or the back electrode 6. As shown in the figure, an electrode terminal is formed from a two-layer film of Al and Ni, and a flexible lead is soldered to this electrode terminal (Japanese Patent Application Laid-Open No. 1983-1999).
89481, Japanese Patent Application Laid-open No. 59-27497). Problems to be Solved by the Invention However, according to the above structure, although it is possible to solder a flexible lead onto an electrode terminal made of a two-layer film of Al and Ni, it is difficult to adhere the underlying Al layer to the glass substrate. Since the force is small, the electrode terminal is likely to peel off from the glass substrate due to external force applied to the flexible lead, resulting in a reliability problem. Means for Solving the Problems This invention provides electrode terminals for transparent electrodes and back electrodes that are formed by laminating a Ti layer, an Al layer, and a Ni layer, and that flexible leads are soldered onto the electrode terminals. This is a characteristic feature. Effects According to the above configuration, the Ti layer has excellent adhesion to the glass substrate and the Al layer, so even if external force is applied to the flexible lead soldered on the electrode terminal, the electrode terminal is prevented from peeling off from the glass substrate. Embodiment FIG. 1 shows an enlarged cross-sectional perspective view of essential parts of a thin film EL panel 20 according to an embodiment of the present invention. Electrode terminal 2
Since the structure is the same as that in FIG. 9 except for the configurations 1 and 22, the same reference numerals are given to the same parts.
The electrode terminals 21 and 22 are made of a Ti layer 23 with a thickness of about 500 Å and an Al layer 23 with a thickness of about 1000 Å on the glass substrate 1.
The layer 24 and the Ni layer 25 having a thickness of about 1000 Å are laminated in this order. Here, one electrode terminal 21 is formed so as to partially overlap the transparent electrode 2, and the other electrode terminal 22 has the back electrode 6 formed so as to partially overlap thereon. A cover glass 13 is adhesively fixed onto these electrode terminals 21 and 22 via an adhesive 14, and a lead pattern 28 made of copper or the like is attached to one side of a resin sheet 27 made of polyethylene or the like via solder 26.
The lead pattern 28 of the flexible lead 29 formed thereon is electrically and mechanically connected and fixed. Figures 2 to 6 show the above thin film EL panel 20.
FIG. 2 shows a plan view of the main parts of each step for explaining the manufacturing method of FIG. First, a large number of transparent electrodes 2 are placed on the top surface of a glass substrate 1.
are formed by arranging their ends in a staggered manner so that every other one can be pulled out in the opposite direction (Fig. 2). Next, a Ti layer 23, an Al layer 24, and a Ni layer are formed by electron beam evaporation, sputtering, etc. at a position that partially overlaps the end of the transparent electrode 2 and a position that partially overlaps the back electrode 6 to be formed in the future. layer 25
are continuously laminated to form electrode terminals 21 and 22 (FIG. 3). Next, the first dielectric layer 3, the light emitting layer 4, the second dielectric layer 5, and the back electrode 6 are sequentially laminated on the transparent electrode 2 to form the thin film EL element 12. At this time, the end portion of the back electrode 6 is formed so as to partially overlap the electrode terminal 22 . 200 to 500 during and/or after the formation of the light emitting layer 4 in order to improve the film quality.
Heat at around ℃. At this time, the electrode terminal 2
The Ti layers 23 of Nos. 1 and 22 diffuse into the glass substrate 1 and firmly adhere to it, and also interdiffuse with the Al layer 24 to firmly adhere to it (FIG. 4). Next, the cover glass 13 is attached with a photocurable adhesive (Photobond) so as to cover the thin film EL element 12.
etc., to form an envelope 15, and the envelope 15 is filled with an insulating protective fluid 16 such as silicone oil and sealed (FIG. 5). Next, the lead pattern 2 of the flexible lead 29 is placed on the electrode terminals 21 and 22 led out to the outside of the cover glass 13 via solder 26, respectively.
8 is connected and fixed (Fig. 6). The electrode terminals 21 and 22 of the above embodiment, the conventional electrode terminal A made of a two-layer film of Al and Ni with the same thickness as the above embodiment, and the conventional electrode terminal A made of a single layer film of Ni with the same thickness as the above example. Regarding electrode terminal B, the soldering area was changed by changing the width of the electrode terminal and the soldering length, and each solder 2 with a thickness of 25 μm was
When the flexible lead 29 was soldered through the electrode terminal 6 and a peel test was conducted, the average peel resistance strength per electrode terminal was as shown in the following table.

[Table] In addition, in conventional thin-film EL panels, the adhesive 14 that adheres the cover glass 13 shrinks when it hardens, and the electrode terminals sometimes peel off due to the stress. As in the example, if the cover glass 13 is bonded onto the electrode terminals 21 and 22, the strong adhesion of the electrode terminals 21 and 22 to the glass substrate 1 will reduce the stress caused by shrinkage of the adhesive 14 when it hardens. , the electrode terminals 21 and 22 will not peel off. However, since the transparent electrode 2 has a strong adhesion force to the glass substrate 1, the transparent electrode 2
As for the side, the cover glass 13 may be bonded directly onto the transparent electrode 2. Furthermore, the transparent electrode 2 may be formed on the entire lower surface of the electrode terminal 21. However, as in the above embodiment, the moisture resistance is better when the end portion of the transparent electrode 2 is placed inside the envelope 15. The reason for this is that the transparent electrode 2 has high crystallinity, and moisture easily infiltrates into the envelope 15 through the grain boundaries. Further, the back electrode 6 may be provided only within the envelope 15 without extending below the cover glass 13 as shown in the above embodiment. Furthermore, the electrode terminals 21 and 22 are connected to the Ti layer 2
The thickness of layer 3 is approximately 50 to 2000 μm, and the thickness of Al layer 24 is approximately 50 to 2000 μm.
Good results can be obtained by setting the thickness of the Ni layer 25 to about 500 to several μm. Effects of the Invention According to the present invention, as described above, since the adhesion between the electrode terminal and the glass substrate is strong, the electrode terminal is prevented from peeling off due to external force applied to the flexible lead soldered to the electrode terminal. Therefore, a highly reliable thin-film EL panel can be obtained.

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional perspective view of a terminal portion of a thin film EL panel according to an embodiment of the present invention. FIGS. 2 to 6 are plan views of essential parts at each stage for explaining the method for manufacturing the thin film EL panel. 7th
The figure is a cross-sectional view of a thin film EL element, and FIG. 8 is a plan view of essential parts showing the arrangement relationship between a transparent electrode and a back electrode. FIG. 9 is a cross-sectional view of a conventional thin film EL panel. 1...Front glass substrate, 2...Transparent electrode, 3,
5... Dielectric layer, 4... Light emitting layer, 6... Back electrode,
13... Rear glass plate, 14... Adhesive, 15...
...Envelope, 16...Insulating protective fluid, 21, 22
... Electrode terminal, 23 ... Ti layer, 24 ... Al layer,
25...Ni layer, 26...Solder, 29...Flexible lead.

Claims (1)

[Scope of Claims] 1. A thin film EL element in which a transparent electrode, a first dielectric layer, a light emitting layer, a second dielectric layer, and a back electrode are laminated in that order on a front glass substrate, and the transparent electrode and the back electrode. and a cover glass covering the thin-film EL element, the electrode terminals being arranged on a transparent glass substrate with a Ti layer,
A thin film EL panel that is formed by sequentially laminating Al and Ni layers and has flexible leads soldered onto each electrode terminal.