JP3232772B2 - Color EL display panel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display panel of an electroluminescence (abbreviated as EL in this specification) light emitting type, and to a color EL display panel which performs color display in combination with a color filter.

[0002]

2. Description of the Related Art An EL display panel has the advantage of being self-luminous in addition to the advantages of a thin flat panel, but it has been practically used up to now because the emission color is limited to yellow-orange. Multicolor display is desired. For this purpose, there is a means for forming the EL light-emitting film as a composite film in which various light-emitting color portions are arranged, but a means for causing the EL light-emitting film to emit almost white light and combining with a color filter is simpler. FIG. 3 shows a typical conventional example of such a color EL display panel.

As is well known, an EL display panel has an insulating film 11.
And a thin film stack 10 of light emitting films 12 and a plurality of lower electrodes 20 and upper electrodes 30 formed in a pattern of thin stripes intersecting each other. The structure is carried on the substrate 1. It is customary to use a transparent plate to take out the EL light emission through the lower part of the figure. However, when combined with the color filter 40, if it is provided on the lower surface side of the substrate 1, a very small pixel on the image display and the corresponding pixel Since the distance corresponding to the thickness of the substrate 1 is large between the color filter portions and color mixture occurs on the display of each pixel, the display light Ld from the light emitting film 12 is taken out upward as shown in the figure. Thus, the color filter 40 is arranged as close as possible to the upper electrode 30 side of the thin film laminate 10.

The light emitting film 12 is made of, for example, SrS containing trace amounts of Ce and Eu, and emits light in a substantially white wavelength range of 450 to 650 nm.
The light emitting film 12 is caused to emit light, and the light emitting film 12 is usually covered on both sides with an insulating film 11 to form a thin film laminate 10. An upper electrode 30 disposed thereon is formed of, for example, ITO (indium tin oxide) for extracting display light Ld. ). The color filter 40 for color display is a filter portion 40r, 40g, 40b of three colors colored with red, green, and blue dyes such as acrylic resin.
The transparent substrate 2 having the transparent substrate 2 supported on the lower surface is integrated with the substrate 1 through a spacer 3 by means such as adhesion. This E
The connection to the drive circuit and the like of the L display panel is made by joining a large number of leads to the protruding portions of the lower electrode 20 and the upper electrode 30 outside the spacer 3.

[0005]

However, the above-described color EL display panel shown in FIG. 3 has a problem that the reliability of connection with an external circuit such as a drive circuit is insufficient. This is because the above-mentioned ITO is generally used for the lower electrode 20 and the upper electrode 30, and it is difficult to obtain good bonding between the ITO and the external connection lead. Of course, it is not necessary to make the lower electrode 20 transparent, and a good connection can be obtained by soldering and joining with a lead if usual nickel-coated aluminum is used. To increase brightness
Since heat treatment needs to be performed at around 600 ° C., there is a problem that aluminum is dissolved at that time, and the adhesion of the aluminum to the substrate is not good. Even if the lower electrode 20 is made of pure nickel having high heat resistance, the adhesion to the substrate is not sufficient. It is of course not allowed to use an opaque metal for the upper electrode 30.

[0006] In view of such circumstances, an object of the present invention is to facilitate the work of connecting the lower electrode and the upper electrode of an EL display panel using a color filter to an external circuit and improve the reliability of the connection.

[0007]

According to the present invention, there is provided a display comprising a thin film stack of an EL light emitting film and an insulating film sandwiched between electrodes from above and below and a combination of color filters. In the panel, the lower electrode and its terminal film are formed as a composite film combining a base film that adheres to the insulating substrate carrying the thin film laminate and a metal film that covers the surface, and the upper electrode is formed from a transparent conductive film Then, the display light generated from the light emitting film is taken out of the panel from the upper electrode side via a color filter, and the lower electrode is connected to an external circuit via a terminal film.
In an L display panel, indium tin oxide or a metal selected from chromium, tungsten, molybdenum, and tantalum is used as a base film, and a metal selected from nickel or a nickel alloy, copper, and gold is used as a metal film. And

[0008] In the above structure, the base film of the composite film is made of ITO.
It is particularly advantageous to use nickel for the metal film. ITO or chromium, tungsten, molybdenum, or tantalum as a base film has good adhesion to an insulating substrate. Nickel or a nickel alloy, copper, or gold as a metal film has a melting point of 600 ° C. or higher and is easily soldered and joined. Note that the upper electrode is preferably connected to a terminal film made of a composite film provided separately from the lower electrode, and the upper electrode is preferably connected to an external circuit via the terminal film. In addition, in order to composite such an underlayer and a metal film, it is practically advantageous to selectively coat the metal film on the underlayer formed in a predetermined pattern by a plating method, particularly an electroless plating method. is there.

[0009]

According to the present invention, in the case of a display panel using a color filter, the lower electrode, which does not need to be transparent, is a composite film composed of a base film and a metal film, and the base film has good adhesion to an insulating substrate. By using a material and a material that has good bondability with the lead etc. when connecting to the metal film,
It is possible to achieve both good adhesion of the lower electrode to the insulating substrate and high reliability of external connection, and it is necessary to use a transparent film for transmitting display light. Use a membrane. As a terminal film for the upper electrode, which is the same as that for the lower electrode, a composite film is separately provided, and the upper electrode is connected to the composite film, whereby the reliability of the external connection can be improved on the upper electrode side.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of a color EL display panel according to the present invention by a sectional view and a top view on the insulating substrate side, and FIG. 2 shows a different embodiment by a sectional view of a main part. Since the same reference numerals are given to the corresponding portions of FIG. 3 and FIG.
The description of the same overlapping portions as in the related art will be omitted as appropriate.

In the sectional view of FIG. 1A, the insulating substrate 1 side and the transparent substrate 2 side are shown in a state where they are slightly separated from each other. The insulating substrate 1 is, for example, a glass plate, and a base film 21 and a metal film
As shown in FIG. 1B, a large number of lower electrodes 20, which are 22 composite films, are provided side by side in an elongated strip pattern. The base film 21 has good adhesion to the insulating substrate 1 such as I
After forming a thin film having a thickness of about 0.2 μm using a sputtering method or a vacuum evaporation method using TO, and using a photoresist film as a mask, the film is etched with a mixed solution of 10% hydrochloric acid and nitric acid to form the pattern described above. I do. Ni having good solderability is used for the metal film 22, and in this embodiment, the Ni is coated on the base film 21 by a selective electroless plating method. Therefore, after sequentially immersing in a tin chloride-based sensitizing solution and a palladium chloride-based activating solution, and then immersing in an electroless plating solution at 80 ° C. for several minutes, Ni is placed on the underlying film 21 to a thickness of, for example, 0.6 μm. The metal film 22 is formed by coating with a film thickness.

In forming the lower electrode 20 of the composite film in this manner, in this embodiment, as shown in FIG. 1 (b), the ends thereof are alternately extended right and left to the periphery of the insulating substrate 1, and the lower electrode 20 is formed.
A slightly wider terminal film 23 for use. At the same time, in the present invention, a terminal film 31 made of the same composite film for the upper electrode 30 is separately provided on the upper and lower peripheral portions of the insulating substrate 1 in this embodiment, as shown in FIG. Side by side.

In this embodiment, the thin film laminate 10 as a light emitting body has a structure in which a light emitting film 12 is sandwiched between insulating films 11 from both sides. As the insulating film 11, a usual silicon nitride or the like is formed to a thickness of about 0.2 μm by a sputtering method or the like, and the light emitting film 12 is made of, for example, Sr containing 0.1% of Ce and Eu to emit white light.
S was evaporated by electron beam evaporation at a substrate temperature of about 300 ° C.
After forming a film having a thickness of about 8 μm, a heat treatment is performed at 550 ° C. for 1 hour to increase the crystallinity and the emission luminance. As a result, a light emitting film 12 that emits white light with high luminance in the wavelength range of 450 to 650 nm is obtained.

The upper electrode 30 is made of IT which is a transparent conductive material.
O was deposited to a thickness of about 0.2 μm,
As shown in FIG. 1B, in the same manner as in the case of FIG. 11, a pattern is formed in which a number of elongated strips are arranged in the vertical direction. In this invention, however, the upper electrodes 30 are alternately connected up and down as shown in FIG. Department
The upper electrode 30 is connected to the above-described terminal film 31 of the composite film through the connecting portion 30a.
Thus, the insulating substrate 1 is in the state shown in FIG. In this embodiment, a color filter 40 composed of mosaic-arranged red, green, and blue filter portions 40r, 40g, and 40b is carried on the lower surface of the transparent substrate 2, and the transparent substrate 2 is bonded via a spacer 3. In the completed state in which it is joined to the insulating substrate 1 by such means as above, it is arranged very close to the upper electrode 30.

A lead is connected to the display drive circuit and the like of the color EL display panel 50 in the completed state by connecting the lead to the lower electrode shown in FIG.
It is preferable to perform soldering on the terminal film 23 for 20 and the terminal film 31 for the upper electrode 30. Since the composite film surface of the terminal films 23 and 31 is covered with the Ni metal film 22 in this embodiment, soldering is easy and reliable connection is obtained. The I of the underlayer 21 is
Since the adhesion of the Ni metal film 22 applied to the TO by the electroless plating method is very good, high connection reliability can be guaranteed over a long use period. Incidentally, in the embodiment of the present invention, the base film 21 is formed.
In addition to ITO, a metal with good adhesion to the insulating substrate 1 such as Cr, W, Mo, Ta, etc., is joined to the metal film 22 by soldering when the melting point of Ni, Ni alloy, Cu, Au, etc. is 600 ° C or more. Can be appropriately used as necessary.

FIG. 2 shows a different embodiment of the present invention by a partial sectional view corresponding to the left part of FIG. 1 (a). The lower electrode 20 of this embodiment is a composite film of a base film 21 and a metal film 22 as in the previous embodiment.
Is formed on the entire surface of the lower electrode 20, and patterning is performed on the elongated lower electrode 20 by photoetching. A nitric acid aqueous solution is used for etching the Ni metal film 22, and a mixed aqueous solution of hydrochloric acid and nitric acid is used for etching the ITO base film 21, respectively. Also in this embodiment, the metal film 22
It is desirable to coat Ni or the like by an electroless plating method in order to enhance adhesion. Further, in this embodiment, for the light emitting film 13 in the thin film laminate 10, SrS containing Mn as a light emission center is formed to a thickness of about 0.8 μm at a substrate temperature of 300 ° C. in the same manner as described above by a sputtering method or the like. By performing the heat treatment for 1 hour, high-luminance emission is performed in the wavelength range from the red region to the green region.

Therefore, in this case, the color filter 41 is composed of red and green filter portions 41r and 41g. In this embodiment, the spacer 3 is first attached to the insulating substrate 1 with the adhesive 4 and Then, the liquid material for the color filter 41 is filled in an area surrounded by the spacer 3, and the filter portions 41r and 41g are colored with red and green dyes in a semi-dried or semi-cured state, and then completely dried or cured. Thereafter, the transparent substrate 2 is attached to the spacer 3 with the adhesive 5 in the groove.
To complete the color EL display panel 50 as shown. In the embodiment of FIG. 2, the display colors are red and green.
Although the color is slightly different, the connection of the external circuit to the terminal film 23 and the like of the lower electrode 20 can be easily and reliably performed by soldering or the like as in the previous embodiment.

[0018]

According to the present invention, attention is paid to the fact that it is not necessary to make the lower electrode side transparent in a display panel using a color filter, and the lower electrode and the terminal film therefor have good adhesion to the insulating substrate. By forming a composite film that combines a base film and a metal film with good bonding properties to the connection partner, it achieves both good adhesion to the insulating substrate and high reliability of connection to the outside, and allows display light to pass through. The required upper electrode was a transparent conductive film. Further, in the present invention, there is no possibility that the lower electrode is deteriorated at a heat treatment temperature required for the light emitting film. Further, by connecting the upper electrode to a terminal film made of a composite film provided separately from that for the lower electrode, high reliability of external connection can be ensured even on the upper electrode side. The present invention can be easily implemented without requiring an increase in the number of steps and adoption of special steps. According to the present invention, a color EL display panel with low cost and high practicability can be realized by taking advantage of a display panel combined with a color filter.

[Brief description of the drawings]

FIGS. 1A and 1B show an embodiment of a color EL display panel according to the present invention, wherein FIG. 1A is a cross-sectional view thereof, and FIG. 1B is a top view of an insulating substrate side.

FIG. 2 is a sectional view of a main part of a color EL display panel showing a different embodiment of the present invention.

FIG. 3 is a cross-sectional view of a conventional color EL display panel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating substrate 2 Transparent substrate 3 Spacer 10 Thin film laminated body 11 Insulating film 12 White light emitting film 13 Red and green light emitting film 20 Lower electrode 21 Underlayer 22 Metal film 23 Terminal film for lower electrode 30 Upper electrode 31 Upper Terminal film for electrode 40 Color filter 50 Color EL display panel Ld Display light

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Harutaka Taniguchi 1-1, Tanabe-Nitta, Kawasaki-ku, Kawasaki, Kanagawa Prefecture Inside Fuji Electric Co., Ltd. (72) Inventor Kazuki Shibata, Tanabe-Nitta, Kawasaki-ku, Kawasaki-ku, Kanagawa Prefecture No. 1 Fuji Electric Co., Ltd. (56) References JP-A-2-162686 (JP, A) JP-A-3-210789 (JP, A) JP-A-2-94387 (JP, A) JP-A Sho 59-48788 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H05B 33/00-33/28

Claims (3)

(57) [Claims] 1. A EL luminescent film and the display panel thereof comprising a combination of entrapment and a color filter by the electrode thin film laminate of the insulating film from above and below, the terminal membrane and the lower electrode, carrying the thin film stack insulating substrate Underlayer that adheres to
And forming a composite film and the metal film are combined to cover the surface, forms the shape of the upper electrode of a transparent conductive film, a display light generated from the light emitting layer is taken out from the upper electrode side outer panel through a color filter and a color EL display panel to be connected to an external circuit via the pin layer of the lower electrodes, as a base film, an indium tin oxide or chromium, data
Metal selected from Ngustene, molybdenum and tantalum
Use and metal film such as nickel or nickel alloy, copper, gold
EL using a metal selected from the group consisting of:
Display panel . 2. The color EL display panel according to claim 1,
The upper electrode is provided separately from the lower electrode.
Connected to a terminal film made of a film, and the upper electrode is connected to the terminal film.
Color EL display panel connected to an external circuit through
Flannel. 3. An apparatus according to claim 1 or 2 color EL display panel according to a color EL display panel of the metal film to a base film coated with selective plating is characterized in that as a composite film .