JPH0112663B2 - - Google Patents

Description

[Detailed description of the invention]

B. Industrial Application Field The present invention relates to a transparent conductive laminate, and more specifically, to a transparent conductive laminate suitable for use in, for example, an electroluminescent display device. B. Prior Art Transparent conductive films or transparent conductive laminates can be used, for example, as electrodes for liquid crystal displays, electrodes for electroluminescence display devices, electrodes for photoconductive photoreceptors, cathode ray tubes, and window portions of various measuring instruments. It is widely used in the electrical and electronic fields, such as electrostatic shielding layers, antistatic layers, and heating elements. Among these, transparent conductive films having selective light transmittance are used as window materials for collectors for utilizing solar energy or as window materials for buildings due to their infrared light reflecting ability. In addition, with the development of information processing, various solid-state displays using electroluminescence, liquid crystal, plasma, and ferroelectric materials have been developed as display devices to replace cathode ray tubes, and these displays have transparent electrodes. is always used.
Furthermore, new electro-optical elements and recording materials that interact or mutually convert electrical and optical signals are being considered useful for future information processing technology.
This also requires a film that is both transparent and conductive. On the other hand, such transparent conductive films can also be used as window glasses for preventing condensation in automobiles, airplanes, etc., as antistatic films for polymers, glass, etc., and as transparent heat-insulating windows for preventing the dissipation of solar energy. In particular, in recent years, there has been an increasing demand for high-pixel displays in liquid crystal displays, electroluminescent displays, plasma displays, electrochromic displays, fluorescent displays, etc., and along with this, electrodes made of transparent conductive layers have been It has been proposed to form a pixel portion using a metal layer and at the same time form a signal application line using a low resistance electrode made of a metal layer, thereby improving the image display speed and image quality. However, in conventional electroluminescent display devices, it is insufficient to reduce the resistance of the electrodes, and when the EL emitting layer and the transparent conductive layer are bonded together by the method described below, the adhesive strength is insufficient. As a result, it was discovered that there was a problem in which peeling occurred between the two, resulting in uneven light emission during operation. C. Object of the Invention The present invention solves the problems of the conventional transparent conductive laminate as described above, and even when used in an electroluminescent display device where the area occupied by the electrodes is large, the light transmittance remains low. It is an object of the present invention to provide a transparent conductive laminate which has a high adhesive strength with a laminate provided with a light-emitting layer, and has a satisfactorily low sheet resistance. D. Structure of the invention That is, the present invention provides indium, tin,
The present invention relates to a transparent conductive laminate in which at least two layers, a transparent conductive layer made of an oxide of at least one of cadmium and antimony, and a metal layer having a thickness of 200 Å or less are sequentially deposited to form a laminate. The materials of each layer constituting the transparent conductive laminate 1 according to the present invention will be described below with reference to FIG. Materials for the base 2 include polyimide, polyethersulfone, polysulfone, polyester resins such as polyethylene terephthalate, polyethylene 2,6-naphthalene dicarboxylate, polydiallyl phthalate, and polycarbonate, and aromatic polyamides, polyamides, polypropylene, and cellulose. Examples include triacetate. Of course, these can be used alone or as a blend as a homopolymer or copolymer. Other organic polymer compounds with excellent heat resistance are not particularly limited, but generally the heat resistance is preferably 80°C or higher. Materials for the transparent conductive layer 3 include indium,
Examples include oxides of at least one of tin, cadmium, and antimony. Typical examples include indium oxide, tin oxide, indium oxide-tin mixture, and tin oxide-antimony mixture. Examples of the material for the metal layer 4 include at least one of indium, tin, cadmium, zinc, titanium, antimony, aluminum, tungsten, molybdenum, chromium, tantalum, nickel, platinum, gold, silver, copper, and palladium. It will be done. In the method for manufacturing a transparent conductive laminate according to the present invention, the transparent conductive layer 3 is formed using indium, tin,
A sputtering method or a reactive vapor deposition method using an indium-tin alloy, a tin-antimony alloy, or an oxide of the above-mentioned material as an evaporation material, or a lower oxide of the above-mentioned material is similarly deposited, and then the deposited layer is heated, oxidized, and discharged. oxidation,
A post-treatment oxidation method using at least one of solution oxidation, or a method such as spray coating may be used.
The metal layer 4 may be formed by a method such as a sputtering method or a vapor deposition method. E. Example Next, the progress that led to the completion of the present invention will be described. Conventionally, in transparent conductive laminates used for liquid crystal displays, metal wiring has been placed over a part of the side edge of the transparent conductive layer, but it has been done to cover a wide range or the entire surface of the transparent conductive layer. No attempt was made to provide a metal layer. As a result of intensive research, the inventor discovered the following. That is, as shown in FIG. 2, there is a transparent conductive laminate 1 formed by successively depositing a transparent conductive layer 3 and a metal layer 4 on a transparent insulating substrate 2, and an electrically protective layer 1 on a metal electrode layer 6. Insulating layer 7 and luminescent layer 8 as layers
A laminate 5 provided with a light-emitting layer formed by sequentially depositing
The transparent conductive laminate 1 and the laminate 5 provided with the luminescent layer are integrated by pasting the metal layer 4 and the luminescent layer 8 together using pressure and heating rollers 9 to produce electroluminescence. When manufacturing a display device, if the thickness of the metal layer 4 is 200 Å or less, the light transmittance will decrease slightly, but the adhesive strength between the transparent conductive laminate 1 and the laminate 5 provided with the light emitting layer will decrease. When the thickness of the metal layer 4 exceeds 200 Å, particularly 250 Å or more, the sheet resistance decreases, but the light transmittance and the above-mentioned adhesive strength decrease significantly. Furthermore, when metals are left in the atmosphere, an oxide film of several tens of angstroms is formed on their surfaces. For example, aluminum is about 20 Å, silver is about 10 Å, and tin is about 50 Å.
It is known that a natural oxide film of about 40 Å is formed on copper. Therefore, the metal layer 4 in the present invention has a natural oxide film on the surface, and when the thickness is set to 100 Å or less, most of the metal layer 4 is in a naturally oxidized state. The present invention has been made based on the above findings. Furthermore, for a transparent conductive laminate made by sequentially depositing a transparent conductive layer and a thin metal layer on a substrate as described above, the thin metal layer and the transparent conductive layer are overlapped and etched using a predetermined mask. This allows easy patterning into a predetermined pattern. FIG. 3 is a plan view showing an example of a transparent conductive laminate patterned as described above, and FIG. 4 is a sectional view taken along the line -- in FIG. 3. A transparent conductive layer 3 and a metal layer 4 deposited thereon are arranged in a predetermined pattern on an insulating transparent substrate (substrate) 2, and from one end of each pixel to the end of the transparent conductive laminate 1. Wiring patterned towards the direction (3a and 3
b) is extended. Normally, the characteristics of a transparent conductive laminate include a light transmittance of 50% or more (preferably 80% or more) at a light wavelength of 550 mμ (the same applies hereinafter), and a sheet resistance of 1.5 kΩ/□
(preferably 1000 Ω/□ or less), and the adhesive strength with the laminate provided with the light emitting layer is desired to be 200 g/2.5 cm or more (display of adhesive strength will be described later). By doing so, the transparent conductive laminate based on the present invention can fully satisfy these demands. The present invention will be specifically explained below using Examples. Example 1 Polyethylene terephthalate (PET) with a thickness of 75 μm was used as the substrate 2, and a transparent conductive film with a thickness of 500 Å was made of a mixture of indium oxide and tin oxide (ITO) (weight ratio of indium and tin 95:5). layer 3
is formed by direct current reaction sputtering using an ITO target or an indium and tin alloy (weight ratio 90:10) target, and a tin layer 4 is deposited thereon with a thickness varying between 0 and 800 Å. A transparent conductive laminate 1 was formed by the above method, and its sheet resistance and light transmittance were measured. However, the thickness of the tin layer 4 was determined by calculation from the value indicated by the evaporation rate meter and the evaporation time. The thickness of the metal layer is the same in other embodiments described later. The metal layer was deposited in a vacuum range of 10 ^-5 Torr to ^{10 -6} Torr, and during sputtering, the Ar gas pressure was in the 10 ^-3 Torr range. The measurement results are shown in FIG. However, the tin layer thicknesses of 0, 400, 600, and 800 Å are values for a comparative transparent conductive laminate. From the same figure, if the thickness of the tin layer 4 is 200 Å or less,
It can be seen that a light transmittance of 50% or more can be obtained. The sheet resistance increases as the thickness of the tin layer 4 decreases, but no matter how thin the tin layer 4 is made, the sheet resistance remains constant.
It will not exceed 1000Ω/□. Furthermore, the composition of the surface of the transparent conductive laminate having a tin metal layer formed by the method described above was analyzed by ESCA analysis. As shown in Figure 6, the tin metal film thickness
Since the binding energy of Sn3d5/2 was 486.4 eV, it was found that the tin metal layer had a tin oxide state on its surface. This is a natural oxide film that metal substances usually have, and is several tens of angstroms thick. The metal layer 4 shown in the present invention is considered to have a natural oxide film. Example 2 Ba was placed on an aluminum plate 6 with a thickness of 0.2 mm.
Ti O ₃ powder was dispersed in a resin and applied to a thickness of several μm using a wire bar and dried. Furthermore, a coating liquid made by dispersing zinc sulfide/manganese powder in a cellulose resin (cyanoethylated cellulose in this example) is applied on top of this, and dried to form a laminate with a luminescent layer 8 having a thickness of several tens of μm. 5 (see Figure 2) was prepared. Since the light emitting layer 8 is formed of a powder dispersed layer as described above, it has a surface with an uneven shape of several tens of micrometers. The laminate 5 provided with this light-emitting layer and the transparent conductive laminate 1 manufactured in the same manner as in Example 1 (however, the thickness of the tin layer 4 is 20 Å) were combined with the tin layer 4 and the light-emitting layer 1. As shown in FIG. 2, the layers 8 and 8 were bonded together using heating and pressure rollers 9 to form an electroluminescent display device. however,
The roller pressure was 1 Kg/cm, the roller temperature was 150° C., and the width dimensions of the transparent conductive laminate 1 and the laminate 5 provided with the light emitting layer were both 2.5 cm. The sheet resistance of this transparent conductive laminate 1 is 330
Ω/□, light transmittance was 82%. The electroluminescent display device thus obtained was manufactured by Toyo Keiki Co., Ltd.
The adhesive strength of the bonded portion was measured using a UTM-type 180° peel tester. The outline of the measurement method is as shown in Fig. 7. One end of the laminate 5 provided with the light emitting layer is fixed, the transparent conductive laminate 1 is pulled in a 180° direction to peel off both, and the tensile distance and peeling are measured. This is a method of determining the relationship between the required load, that is, the adhesive strength. The test results are shown by curve a in FIG.
Although the peeling load decreases when the tensile distance is 1 mm or less, this is based on play in the chuck part (not shown) of the testing machine and does not indicate the true load. For comparison, the same figure also shows the results of a similar test conducted on an electroluminescent display device manufactured under the same conditions as this example without providing the tin layer 4, as a curve b. There is. Electroluminescent display devices using comparative transparent conductive laminates had adhesive strengths of 70 to 120.
g/2.5cm, indicating no satisfactory adhesive strength. On the other hand, in an electroluminescent display device using the transparent conductive laminate according to the present invention, the adhesive strength is approximately 250 g/2.5 cm, which is sufficient adhesive strength. Next, the following Examples 3 to 10 will be described in which tests similar to those in this example were conducted by changing the type of transparent conductive layer and the material and thickness of the metal layer. The substrate, the laminate provided with the light-emitting layer, and the bonding method in these examples are the same as in Example 2 above. Example 3 The transparent conductive layer was made of ITO with a thickness of about 500 Å (above Example 2).
The sheet resistance, light transmittance, and adhesive strength were measured in the same manner as in Example 2, using indium as the material of the metal layer and a thickness in the range of 0 to 300 Å. The results are shown in FIG. However, since the values when no metal layer is provided (thickness: 0 Å) cannot be plotted in the figure, they are written in parentheses around the broken line arrows. (The same applies hereafter). Moreover, this value and the value plotted at the point where the metal layer thickness exceeds 200 Å are the values of the comparative example (the same applies hereinafter). Example 4 The material of the metal layer is tin, and its thickness is 0 to 600 Å.
The range of The rest is the same as in the third embodiment. The results are shown in FIG. Example 5 The material of the metal layer was aluminum, and its thickness was in the range of 0 to 600 Å. Others are the same as in Example 3 above.
The same is true in . The results are shown in FIG. Example 6 The material of the metal layer is copper, and its thickness is 0 to 400 Å.
The range of The rest is the same as in the third embodiment. The results are shown in FIG. Example 7 The material of the metal layer is chromium and its thickness is 0 to 500.
The range was set at Å. The metal layer was formed by a sputtering method. The rest is the same as in the third embodiment. The results are shown in FIG. Example 8 The material of the metal layer is palladium, and its thickness is 0.
The range was ~400 Å. The rest is the same as in the seventh embodiment. The results are shown in FIG. Example 9 A transparent conductive layer was formed using a mixture of tin oxide and antimony (2% by weight of antimony) with a thickness of about 700 Å, which was formed by a direct current reaction sputtering method, and the other aspects were the same as in Example 4 above. The results are shown in FIG. Example 10 The transparent conductive layer was the same as in Example 9, and the rest was the same as in Example 5. However, the thickness of the aluminum layer was in the range of 0 to 300 Å. The results are shown in FIG. The results of Examples 3 to 10 above are summarized in Table 1 below.

【table】

[Table] indicates disqualification.
The following can be understood from the results of Examples 3 to 10 above. (1) When the thickness of the metal layer exceeds a certain value, the light transmittance decreases, but if it is 200 Å or less, a light transmittance of 50% or more can be maintained, and if this is 100 Å or less, the light transmittance is 75% or more. , a light transmittance of 80% or more can be maintained at a thickness of 50 Å or less. (2) Sheet resistance increases as the thickness of the metal layer decreases, but no matter how thin the metal layer is, the
A sheet resistance of Ω/□ or less is maintained. (3) The adhesive strength shows a maximum value in the range of metal layer thickness of 50 to 100 Å, and as the metal layer becomes thicker beyond this range, the adhesive strength decreases, but up to the metal layer thickness of 200 Å. Adhesive strength of 200g/2.5cm or more is maintained. Further, when the metal layer has a thickness of 1 to 2 Å or more, an adhesive strength of 200 g/2.5 cm or more is maintained.
However, the thickness of the metal layer is between 2.5-5 Å and 20-25 Å.
Since the change in adhesive strength is small in the range of
The thickness of the metal layer is preferably 3 Å or more, particularly preferably 5 Å or more. On the other hand, from the viewpoint of the above-mentioned light transmittance, it is particularly preferable that the thickness of the metal layer is in the range of 5 to 50 Å. The reason why the adhesive strength increases as the thickness of the metal layer increases, reaches a maximum value, and then decreases is considered to be as follows. In order for the transparent conductive laminate and the laminate provided with the light-emitting layer to adhere firmly, (a) the compatibility between the two (wetting property between the two when the light-emitting layer is softened by heating with a roller) is good. (b) The contact area between the two must be large. By the way, (1) when directly adhering the light-emitting layer and the transparent conductive layer without providing a metal layer on the transparent conductive laminate, the transparent conductive laminate has flexibility and conforms to the uneven shape of the surface of the light-emitting layer. Although a large contact area can be maintained during roller pressure, since the transparent conductive layer is formed in a highly oxidized state, it does not have good compatibility with the light emitting layer, and the two do not adhere to each other with sufficient strength. (2) When adhering a transparent conductive laminate in which a metal layer of an appropriate thickness is provided on a transparent conductive layer to a light emitting layer,
Since the flexibility of the transparent conductive laminate does not deteriorate much, it is possible to maintain a large contact area with the irregular shape of the surface of the light emitting layer, and also improves the compatibility of the light emitting layer with the metal layer when bonded by pressure or heat. Because they have similar properties, the two adhere with strong adhesive force. (3) Even if a metal layer is provided on the transparent conductive layer, if it is too thin, the formation of the metal layer will be incomplete and the metal layer will not be formed partially, and the effect of the presence of the metal layer will not be sufficient. The adhesion of the formed metal layer to the transparent conductive layer is not perfect, and the metal layer easily peels off from the transparent conductive layer, resulting in a decrease in adhesive strength. (4) If the thickness of the metal layer becomes too thick, this transparent conductive laminate loses its flexible properties.
The contact area with the uneven shape on the surface of the light emitting layer cannot be increased, and the adhesive strength decreases. In addition to Examples 3 to 10 described above, the results were as follows when the metal layer was formed by sputtering and the following metals were used as the material. When cadmium and zinc are used as the metal layer material, almost the same results are obtained as when tin is used as the metal layer material, and when the metal layer material is titanium, antimony, tungsten, platinum, gold, silver, molybdenum, and tantalum. When nickel was used, almost the same results were obtained as when chromium or palladium was used as the metal layer material. In all of the above embodiments, a metal layer is provided over the entire surface of the transparent conductive layer, but this metal layer is applied to a range where the adhesive strength can be satisfied (for example, 50% of the surface of the transparent conductive layer). It is also possible to provide the above). Furthermore, although the above examples are all examples of transparent conductive laminates consisting only of a substrate, a transparent conductive layer, and a metal layer, it is also possible to It is also possible to provide other layers, such as an ultraviolet absorbing filter layer, an antireflection film, a water replenishing layer, etc., between the layers or on the surface of the substrate opposite to the surface on which the transparent conductive layer is applied. In addition, when the metal layer material is aluminum, for example, a thin layer of alumina is formed on the surface of the metal layer due to natural oxidation.
The presence of such a thin oxide film increases the sheet resistance,
There is almost no adverse effect on light transmittance and adhesive strength, and there is no problem at all. F. Effects of the Invention As explained above, the transparent conductive laminate according to the present invention is constructed by sequentially depositing at least a transparent conductive layer and a metal layer on a substrate, and the metal layer has a thickness of 200 Å or less. This transparent conductive laminated layer has sufficient light transmittance because of its high transparency, and when applied to a light emitting display device, has high adhesive strength with the light emitting layer and has a sufficiently low sheet resistance. It has extremely excellent physical properties. Therefore,
For example, when using the transparent conductive laminate according to the present invention as a transparent conductive laminate for an electroluminescent display device, the brightness and contrast of the display pattern are good, and peeling between the light emitting layer and the transparent conductive layer does not occur. This prevents brightness unevenness and allows you to obtain clear images over a long period of time.

[Brief explanation of drawings]

The drawings all show examples of the present invention, and FIG. 1 is a cross-sectional view of a transparent conductive laminate, and FIG.
The figure is a cross-sectional view showing a method of bonding a transparent conductive laminate and a laminate provided with a light-emitting layer, and FIG. 3 is a plan view of a transparent conductive laminate in which a transparent conductive layer and a metal layer are patterned into a predetermined pattern. Figure 4 is a sectional view taken along the line - in Figure 3, Figure 5 is a graph showing the relationship between the thickness of the metal (tin) layer, sheet resistance and light transmittance, and Figure 6 is a graph showing the relationship between the thickness of the metal (tin) layer and the sheet resistance and light transmittance. ) shows ESCA surface analysis data of a transparent conductive laminate having a layer. Figure 7 is a cross-sectional view showing the peel test method, Figure 8 is a graph showing the relationship between tensile distance and peeling load in the peel test, Figures 9, 10, 11, 1
Figures 2, 13, 14, 15 and 16
The figure is a graph showing the relationship between the thickness of the metal layer, sheet resistance, light transmittance, and adhesive strength. In addition, in the symbols shown in the drawings, 1...transparent conductive laminate, 2...substrate, 3...transparent conductive layer, 4...metal layer, 5... laminate provided with a light emitting layer, 8...Light emitting layer, 9...Pressure and heating roller.

Claims (1)

[Claims] 1. A transparent conductive material in which at least two layers, a transparent conductive layer made of an oxide of at least one of indium, tin, cadmium, and antimony and a metal layer with a thickness of 200 Å or less are sequentially deposited on a substrate to form a laminate. Sex laminate.