JPH06110073A - Terminal lead-out structure of display element - Google Patents

Abstract

PURPOSE:To provide the terminal lead-out structure which can increase the adhesive strength of a connection part between a transparent conductive layer and a metallic conductive layer laminated thereupon. CONSTITUTION:On a substrate 21, the transparent conductive film 23 which is led out of a liquid crystal display element 22 is formed, a chromium film 24 is formed thereupon, and an aluminum film 25 is formed further thereupon. The peripheral edges of the aluminum film 25 and chromium film 24 are inside the transparent conductive film 23. The terminal lead-out part of the liquid crystal display element 22 and the terminal part of an IC are electrically connected by wire bonding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a terminal portion drawn out from a transparent conductive film in a display device such as a liquid crystal display device for electrical connection by wire bonding.

[0002]

2. Description of the Related Art FIG. 5 is a perspective view of a terminal lead portion of a conventional liquid crystal display element. Such a terminal lead-out structure is disclosed in, for example, Japanese Utility Model Publication No. 4-25729. In the terminal lead-out portion shown in FIG. 5, in order to connect the liquid crystal display element 2 to the outside on the substrate 1, a transparent conductive film 3 such as indium oxide (ITO) containing tin oxide is formed, and a chromium film 4 is formed thereon. It is formed, and the aluminum film 5 is further formed on it. The liquid crystal display element 2 has an integrated circuit (IC) for driving the liquid crystal display element 2 mounted on one side of the substrate 1 for the purpose of downsizing and high reliability. The terminal lead-out portion of the liquid crystal display element 2 and the IC terminal portion are
It is electrically connected by wire bonding. The method of connecting in this way is called the COG method. When connecting by this wire bonding, the liquid crystal display element 2
The surface of the terminal lead-out portion is required to be made of a material having a high adhesion strength with the bonding wire, so that the aluminum film 5 is formed. Since the adhesion strength between the transparent conductive film 3 and the aluminum film 5 is insufficient, an intermediate layer such as the chromium film 4 is interposed to enhance the adhesion strength.

[0003]

In the liquid crystal display device, the pitch of the wiring pattern is becoming narrower as the function and size of the liquid crystal display device are made smaller. As a result, the surface area of the terminal lead-out portion formed on the transparent conductive film of the liquid crystal display element also becomes small,
Sufficient adhesion cannot be obtained. Therefore, when wire bonding 10 is performed as shown in FIG. 6, a part of the terminal lead-out portion of the liquid crystal display element may be separated from the interface between the transparent conductive film 3 and the chromium film 4. Figure 6
FIG. 6A is a side view of the terminal lead-out portion in a peeled state by wire bonding, and FIG. 6B is a perspective view thereof. One of the causes of the peeling of the terminal lead-out portion is a decrease in the adhesive force due to the reduction of the surface area of the terminal lead-out portion, but the adhesive force is not determined only by the surface area of the terminal lead-out portion. That is, the adhesion of the terminal lead-out portion is greatly affected by the adhesion state of the laminated layers such as the transparent conductive film 3, the chrome film 4 and the aluminum film 5.

FIG. 7 is a sectional view of a conventional terminal lead portion. The layers such as the transparent conductive film 3, the chrome film 4, and the aluminum film 5 are all laminated in the same area and the same shape, and are in a uniform state. When manufacturing such a terminal lead portion, three layers of the transparent conductive film 3, the chromium film 4 and the aluminum film 5 are formed on the substrate 1 by a thin film forming method called sputtering. Next, a positive resist is applied on the formed film, exposed through a mask having a predetermined pattern, developed, and each layer is etched. At this time, first, etching is performed by passing through the etching solution for the uppermost aluminum film 5, and cleaning is performed, and then etching is performed through the etching solution for the chromium film 4 and cleaning is performed. Further, etching is performed by passing through an etching solution for the transparent conductive film 3,
To wash. In this way, when the etching process is completed, the positive resist can be peeled off by the resist peeling process to form a desired pattern of the terminal lead portion. It should be noted here that, in the series of steps, when the transparent conductive film 3 is etched, the etching solution is
And the chrome film 4 and the pattern edge portion 12 is turned over as shown in FIG. As a result, the adhesion between the transparent conductive film 3 and the chrome film 4 is reduced, and the adhesion of the entire terminal lead-out portion is reduced.

An object of the present invention is to provide a terminal lead-out structure capable of strengthening the adhesion of a transparent conductive layer and a metal conductive layer laminated on the transparent conductive layer.

[0006]

According to the present invention, there is provided a terminal lead-out structure for a display element, comprising a transparent conductive layer and at least one metal conductive layer laminated on the transparent conductive layer to form a wire bonding pattern. The terminal lead-out structure of the display element is characterized in that the peripheral edge of is inside the peripheral edge of the transparent conductive layer.

[0007]

According to the present invention, in the wire bonding pattern which is the terminal lead-out portion of the display element, the peripheral edge of the metal conductive layer is formed inside the peripheral edge of the transparent conductive layer. For example, each layer is formed separately from the pattern manufacturing process of the transparent conductive film and the pattern manufacturing process of the metal conductive layer. Since such a manufacturing method is possible, since the etching solution for the transparent conductive layer does not soak into the interface between the transparent conductive layer and the metal conductive layer, it is possible to prevent the edge portion of the wire bondin pattern from being turned up. Therefore, it is possible to enhance the adhesion strength of the bonding portion between the transparent conductive layer and the metal conductive layer laminated thereon.

[0008]

1 is a perspective view of a terminal lead-out portion of a liquid crystal display device according to an embodiment of the present invention. A transparent conductive film 23 drawn from the liquid crystal display element 22 is formed on the substrate 21,
A chrome film 24 is formed thereon, and an aluminum film 25 is further formed thereon. The liquid crystal display element 22 is electrically connected to this terminal lead portion through the transparent conductive film 23. The liquid crystal display element 22 has an IC for driving the liquid crystal display element 22 mounted on one side of the substrate 21 for the purpose of achieving compactness and high reliability. The terminal lead portion of the liquid crystal display element 22 and the terminal portion of the IC are electrically connected by wire bonding. When connecting by this wire bonding, the liquid crystal display element 2
An aluminum film 25 is formed on the surface of the terminal lead-out portion 2 because a material having high adhesion strength with the bonding wire is required. Further, since the adhesion strength between the transparent conductive film 23 and the aluminum film 25 is insufficient, an intermediate layer such as the chromium film 24 is interposed to enhance the adhesion strength. Further, the pattern edge of the chrome film 24 is formed inside the pattern edge for the transparent conductive film to prevent the pattern edge portion from being turned up due to the penetration of the etching solution in the manufacturing process.

FIG. 2 shows a manufacturing process of a terminal lead portion of the liquid crystal display element in the embodiment shown in FIG. 2A, a transparent conductive film (2) made of ITO is formed on the substrate 21.
000A) 23, a chromium film (500A) 24, and an aluminum film (10000A) 25 are sequentially formed by a thin film forming method called sputtering. In addition, "A" shall represent angstrom. Next, in the step shown in FIG. 2B, a positive resist 26 is applied on the formed aluminum film 25, exposed through a mask 27 having a predetermined pattern, and developed in the step shown in FIG. I do. Next in FIG.
(D) In the illustrated step, etching is performed based on the developed predetermined pattern. First, an aluminum etching solution such as a mixed acid solution containing phosphoric acid is passed through the uppermost aluminum film 25 to perform etching and cleaning. After that, the chromium film 24 is cleaned by passing an etching liquid for chromium such as a ceric ammonium nitrate solution or the like through the etching. Next, in a step shown in FIG. 2E, the resist is peeled off, the positive resist 26 is peeled off, and the aluminum film 25 and the chromium film 24 can be formed into a desired pattern.
In the steps shown in FIGS. 2F to 2I, the pattern edge of the transparent conductive film 23 is 5 to 10 μm larger than the pattern edges of the aluminum film 25 and the chromium film 24 formed in the previous step.
This is a process for forming on the outside. In the step shown in FIG. 2F, the positive resist 30 is applied again to the pattern formed in the step shown in FIG.
2 is exposed through a mask 31 for forming the pattern and developed in the step shown in FIG. In the step shown in FIG. 2H, etching is performed by passing through an etching solution for the ITO transparent conductive film, such as hydrochloric acid-based mixed acid, and cleaning is performed. It should be noted here that when the etching solution for the transparent conductive film is passed, the chromium film 24 is protected by the positive resist 30, so that the etching solution is used as the transparent conductive film 2.
3 and the chrome film 24 do not soak into the interface. Therefore, it is possible to prevent the pattern edge portion of the chrome film 24 from being turned up. In the resist stripping step shown in FIG. 2I, the positive resist 30 is stripped, and a desired pattern can be formed. Therefore, it is possible to form the lead terminal portion in which the pattern edge of the metal conductive film such as aluminum or chrome is inside the pattern edge of the transparent conductive film 23. Further, thereafter, in order to reduce the resistance of the transparent conductive film, it may be fired at 300 ° C.

FIG. 3 shows a manufacturing process of a terminal lead portion of a liquid crystal display element in another embodiment of the present invention. This embodiment is similar to the embodiment of FIG. 2, and the corresponding parts are designated by the same reference numerals. In the step shown in FIG. 3A, a transparent conductive film (2000A) 23, a chromium film (500A) 24, and an aluminum film (10000A) 25 are sequentially formed on the substrate 21 by a thin film forming method called sputtering. Next, in the step shown in FIG. 3B, the positive resist 26 is formed on the formed aluminum film 25.
Is applied, exposed through a mask 40 having a predetermined pattern, and developed in the step shown in FIG. Next, in the step shown in FIG. 3D, etching is performed based on the developed predetermined pattern. First, an aluminum etching solution is passed through the uppermost aluminum film 25 to perform etching and cleaning. After that, the chromium film 24 is etched by passing an etching liquid for chromium and washed. Further, the transparent conductive film 23 is washed by passing an etching liquid for the transparent conductive film through etching. The reference numeral 41 indicates the transparent conductive film 2.
At the time of the etching of 3, the etching liquid is the transparent conductive film 2.
3 enters the interface between the chrome film 24 and the chrome film 24, causing swelling,
This is the part where the adhesion is reduced. Next, in a step shown in FIG. 3E, the resist is peeled off to remove the positive resist 26.
Peel off. The formed pattern at this time is a state in which all layers are aligned with the pattern of the completed transparent conductive film 21 and has the same shape. Next, in the step illustrated in FIG. 3F, the positive resist 42 is applied again to the substrate 21 on which the pattern is formed. Thereafter, a pattern mask 43 is formed so as to form the aluminum film 25 and the chrome film 24 slightly inside the pattern edge of the transparent conductive film 23 on which the pattern has already been formed, and then exposed, as shown in FIG.
Development is performed in the illustrated process. This is to remove the portion 41 formed in the step shown in FIG. 3D and having a reduced adhesion. Next, in a step shown in FIG. 3H, etching is performed based on the developed predetermined pattern.
First, an aluminum etching solution is passed through the uppermost aluminum film 25 to perform etching and cleaning. After that, chrome film 2
An etching solution for chromium is passed through 4 to etch and wash. Therefore, in this step, it is possible to remove the portion 41 formed in the step shown in FIG. 3D and having a reduced adhesion. In the step shown in FIG. 3I, the resist can be stripped off to remove the positive resist 42 to form a desired pattern. Therefore, it is possible to form the terminal lead-out portion in which the pattern edge of the metal conductive layer such as aluminum and chromium is inside the pattern edge of the transparent conductive film.

FIG. 4 is a pattern configuration diagram of a terminal lead portion of the liquid crystal display element in each of the above embodiments. Wire bonding with an IC was actually performed in this terminal lead portion, and the conditions at that time were using a wire bonder HW2200 manufactured by Kyushu Matsushita Electric Co., Ltd., and connection was performed using a 32 μm gold wire. The state of the pattern of the terminal lead-out portion in this case showed better adhesion than the conventional product as a result of comparison with the conventional product. That is, the peeled state as shown in FIG. 6 did not occur.

In the embodiment of the present invention, the case where aluminum is used as the conductive layer and chromium is used as the intermediate layer has been described. However, the conductive layer has good adhesion to a bonding wire such as gold or silver. As a matter of course, a material such as nickel or titanium may be used as the intermediate layer. Further, the number of manufacturing steps may be increased so that the shape of the intermediate layer and the shape of the uppermost layer may be different. Furthermore, in the manufacturing method in which the etching steps of the conductive layer and the transparent conductive layer are separated, since the etching solution for the transparent conductive layer does not contact the conductive layer such as aluminum, the degree of freedom in selecting the film quality of the transparent conductive layer is increased.

[0013]

As described above, according to the present invention, in the terminal lead-out structure of the display element on which the wire bonding pattern is formed, the metal conductive layer is formed so that the peripheral edge thereof is inside the peripheral edge of the transparent conductive layer. By doing so, it is possible to strengthen the adhesive force at the joint between the metal conductive layer and the transparent conductive layer. As a result, peeling of the wiring pad during wire bonding can be prevented, and reliability and manufacturing yield can be improved. Further, although the present invention requires a mask change in the manufacturing process, it can be easily implemented only by combining conventional processes.

[Brief description of drawings]

FIG. 1 is a perspective view of a terminal lead portion of a liquid crystal display element according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a manufacturing process of a terminal lead-out portion of the liquid crystal display element in the embodiment shown in FIG.

FIG. 3 is a cross-sectional view showing a manufacturing process of a terminal lead portion of a liquid crystal display element according to another embodiment of the present invention.

FIG. 4 is a plan view showing a pattern configuration of a terminal lead-out portion of the liquid crystal display element in the embodiment shown in FIGS. 1 and 3.

FIG. 5 is a perspective view of a terminal lead portion of a conventional liquid crystal display element.

6A and 6B are a cross-sectional view and a perspective view showing an example of peeling a conductive layer in a terminal lead-out portion during conventional wire bonding.

FIG. 7 is a cross-sectional view of a conventional terminal lead portion.

[Explanation of symbols]

 21 substrate 22 liquid crystal display element 23 transparent conductive film 24 chrome film 25 aluminum film

Claims (1)

[Claims] 1. A terminal lead-out structure for a display device, comprising a transparent conductive layer and at least one metal conductive layer laminated on the transparent conductive layer, and a wire bonding pattern is formed on the transparent conductive layer. A terminal lead-out structure for a display element, which is located inside.