JPS62264591A - Manufacture of thin film electroluminescence panel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] The present invention provides a thin film electroluminescence panel (hereinafter referred to as an EL panel) that is manufactured and then applied with a direct current voltage between a transparent electrode and a back electrode. By destroying parts with low pressure resistance in advance, fatal destruction of the EL panel can be prevented and manufacturing yield can be improved.

(Industrial Application Field) This invention relates to a method of manufacturing a thin film electroluminescent panel.

Recently, thin film EL panels have been widely used for illuminating instrument panels, various dials, road signs, etc. because they are easy to fabricate as surface light sources. This thin film EL panel has a disadvantage in that the yield during the manufacturing process is poor and the manufacturing cost is higher than that of light emitting diodes.

Therefore, there is a need for a method of manufacturing thin film electroluminescent panels that can be manufactured with high yield.

[Conventional technology]

Conventionally, thin-film EL panels are made by forming a transparent electrode made of indium oxide doped with tin on a glass substrate, and applying manganese (Mn), which is an activator, to zinc sulfide (ZnS), which becomes the EL emitting layer, on this transparent electrode. For example, 5,000 layers of metal are deposited to a thickness of 5,000, and a metal with a high light reflectance is further deposited via an insulating layer to form a back electrode.

In order to measure the brightness at the end of manufacturing (when the panel is completed), this thin-film EL panel has an alternating voltage applied between the transparent electrode and the back electrode, for example, a pulse width of 25 μs and a voltage of 2 with a period of 60 Hz.
Initial light emission is performed by applying an alternating voltage of 00V. After the brightness measurement using this initial light emission is completed, the product is manufactured through an aging process. During this luminance measurement or aging, that is, while applying an alternating voltage to the thin film EL panel, the thin film EL panel may be destroyed.

This is because the electric field due to the alternating voltage applied to make the thin film EL panel emit light is as high as 2000 KV/(J), which causes the insulation layer to break down. There are two types of EL panels. One is a self-heal mode in which the fracture occurs only locally in the thin-film EL panel, and the other is a self-heal mode in which once a fracture occurs, continuous fracture occurs and the fracture spreads. This is a fatal proper gate mode that develops until the back electrode becomes disconnected.

Note that the frequency of breakage of thin film EL panels occurs as shown in FIG. That is, as the alternating voltage is increased, the number of points at which the self-heal mode breaks down changes as shown in the figure, and the alternating voltage of 200 V, which actually drives the thin-film EL panel, changes as shown in the figure.
Destruction also occurs in the following.

On the other hand, in order to improve the manufacturing yield, various measures are taken to prevent the self-heal mode from developing into the proper gate mode, such as laminating two or more insulating layers with different coefficients of linear expansion on the back electrode side. This is also being done.

[Problem that the invention seeks to solve]

The conventional thin film EL panel manufacturing method described above is based on the thin film EL panel manufacturing method.
Once destruction occurs when measuring the brightness of the panel,
Destruction occurs continuously and becomes proper gate mode,
There was a problem in that the back electrode was turned off and the product yield was reduced.

In this invention, from the above conventional situation, thin film EL
The object of the present invention is to provide a method for manufacturing thin film aluminum panels that does not reduce the yield of panel manufacturing.

[Means for solving problems]

In this invention, at the end of manufacturing a thin film EL panel, and prior to the initial light emission and aging process, a direct current voltage is applied between the transparent electrode and the back electrode to preliminarily destroy portions that have low withstand voltage and are likely to be destroyed.

[Effect]

Generally, when a thin-film EL panel is destroyed by applying an alternating voltage, the back electrode on the periphery of the broken part remains in its current state, except for the broken part, and has already been degraded by the next applied alternating voltage. The periphery is destroyed, and destruction occurs continuously and develops into proper gate mode. On the other hand, when a DC voltage is applied to a thin-film EL panel, the back electrode at the periphery of the area destroyed by the DC voltage peels off from the insulating layer, and the next voltage is not applied to this periphery and is continuous. It becomes a self-heal mode of destruction that does not cause destruction.

〔Example〕

FIG. 1 is a sectional view of an embodiment in which the present invention is applied, and a thin film EL panel includes an indium oxide film on a glass substrate 1,
A transparent electrode 2 made of tin oxide is formed to a thickness of 2000 mm,
A lower insulating layer 3 made of silicon nitride (S i3 N4 ) is coated on this transparent electrode 2 to a thickness of 2000 mm, and an emissive layer 4 made of zinc sulfide (ZnS) and manganese (Mn) is coated on this lower insulating layer 3. Form 5000 people.

An upper insulating layer 5 (thickness: 1,500 mm) is formed on this EL light emitting layer 4, and an upper insulating layer 6 (thickness: 500 mm) having a different coefficient of linear expansion from that of the upper insulating layer 5 is formed on top of this.
A back electrode 7 (2000 thick AN) is formed on the upper insulating layer 6.

In this thin film EL panel, the upper insulating layer on the side of the back electrode 7 is formed in a double structure to prevent destruction in the proper gate mode, which causes continuous destruction. EL panels, on the other hand, are self-healing.
Some modes are prone to mode breakdown, and some develop from self-heal mode to proper gate mode.

As described above, an alternating voltage is applied between the transparent electrode 2 and the back electrode 7 to measure the brightness of the thin film EL panel manufactured in this way. Then, a DC voltage is applied between the transparent electrode 2 and the back electrode 7 by a DC power supply 8. This voltage application is performed in a state where the back electrode 7 is connected at one end in a comb-teeth shape.

This applied DC voltage is 20% higher than the peak value of the alternating voltage actually used for light emission, and by applying this voltage, parts of the insulating film with low breakdown voltage are destroyed. In other words, the self-heal mode is destroyed. Therefore, by destroying the weak points in this insulating film in advance, destruction of the proper gate mode in the subsequent initial light emission and aging steps can be prevented.

Note that the reason why the DC voltage is set higher than the alternating voltage is that when a DC voltage is applied, the withstand voltage distribution shifts to about 20% lower than when an alternating voltage is applied.

FIG. 2 shows another embodiment of the present invention, in which a resistor 9 (IMΩ) is inserted in the connection line between the DC power source 8 and the back electrode 7, and self-heal mode breakdown is gradually generated from a low voltage. , has the special effect of reducing the local area of destruction.

〔effect〕

As is clear from the above description, according to the present invention, destruction of the proper gate mode can be achieved by simply passing through a simple step of applying a DC voltage in the initial light emission and pre-aging steps of the manufactured thin film EL panel. If this invention is applied to the production of thin film EL panels, it will have extremely beneficial effects in improving yield and quality.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a thin film EL panel showing one embodiment of the present invention, Fig. 2 is a sectional view of a thin film EL panel showing another embodiment of the invention, and Fig. 3 is a breakdown frequency diagram of the thin film EL panel. It is. In the figure, 2 is a transparent electrode, 3 is a lower insulating layer, and 4 is an EL
A light emitting layer, 5 and 6 are upper insulating layers, 7 is a back electrode, and 8 is a DC power source. ■ Book @ Bank Alfl Ur= -'Odor Hii row's bottom box Fig. 1 Fig. 2

Claims (1)

[Claims] A transparent electrode (2), an insulating layer (3), an electroluminescent layer (4) and an insulating layer (5) are formed on a glass substrate (1).
, 6) and the back electrode (7) to produce a thin film electroluminescent panel, the transparent electrode (
2) A method for manufacturing a thin film electroluminescent panel, characterized in that a DC voltage is applied between the back electrode (7) and the portions of the insulating film with low breakdown voltage are destroyed in advance.