Double-sided ITO etching process

Abstract

The invention relates to the technical field of etching, and particularly discloses a double-sided ITO etching process. Comprising the following steps: covering a protective layer on the back surface, coating a photo-sensitive resist on the front surface, exposing for the first time, developing for the first time, etching the front surface, cleaning for the first time, covering the protective layer on the front surface, coating the photo-sensitive resist on the back surface, exposing for the second time, developing for the second time, etching the back surface and cleaning for the second time. According to the double-sided ITO etching process, before one surface of the substrate is coated with the photosensitive resist for exposure and development, the other surface of the substrate is covered with the protective layer, so that the situation that the pattern formed by exposure / development is contacted during secondary coating of the photosensitive resist to cause smudginess and further cause a poor circuit during subsequent etching is avoided; the bottom of the substrate is firstly covered with the protective layer, so that the strict requirement of the conventional ITO etching process on the cleanliness of the workbench is reduced, the production efficiency is effectively improved, and the yield is also greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of etching, and in particular discloses a double-sided ITO etching process. Background Art

[0002] In the process of preparing display character patterns on transparent conductive glass, ITO etching technology plays a vital role. ITO, or indium tin oxide, is a transparent conductive material widely used in the thin film and semiconductor industries. Electrode photolithography technology, as a comprehensive precision surface processing technology combining graphic copying and chemical etching, is crucial to the production of liquid crystal displays (LCDs). Its core purpose is to coat a layer of photosensitive resin on the conductive glass substrate according to product design requirements and perform precise exposure. Subsequently, with the protection of the photoresist, the ITO conductive layer is selectively chemically etched to form a pattern on the ITO conductive glass that is completely consistent with the mask. This process requires not only extremely high precision, but also the clarity and consistency of the pattern to meet the growing demand for display technology.

[0003] ITO etching technology is divided into single-sided ITO etching and double-sided ITO etching. Single-sided ITO etching is mainly used for applications that only need to form a conductive pattern on one side of the conductive glass, while double-sided ITO etching is used for complex applications that need to form conductive patterns on both sides of the conductive glass, such as the production of capacitive touch screens. Figure 1 The existing double-sided ITO etching process is as follows: first coating of photosensitive resin on the front side---exposure---development---first coating of photosensitive resin on the back side---front etching---resistance removal---second coating of photosensitive resin on the back side--exposure---development---second coating of photosensitive resin on the front side---back etching---resistance removal.

[0004] However, the existing process is not only time-consuming, but also in the process of coating the photosensitive adhesive on the back for the first time, it is easy to cause contamination to the photosensitive adhesive pattern formed on the front; similarly, when coating the photosensitive adhesive on the front for the second time, it is also easy to cause contamination to the photosensitive adhesive pattern on the back. The existing double-sided ITO etching requires workers to operate with high precision. In addition, the existing process has strict requirements on the cleanliness of the workbench, and the workbench needs to be cleaned for each operation, otherwise it is easy to cause contamination to the photosensitive adhesive or ITO pattern, which is not conducive to the yield rate. Therefore, the existing process not only reduces production efficiency, but also makes it difficult to reduce the scrap rate, which has a serious impact on production costs and product quality. Therefore, the development of a more efficient and clean double-sided ITO etching process is of great significance to improving the production efficiency and reducing costs of liquid crystal displays. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a double-sided ITO etching process.

[0006] The present invention discloses a double-sided ITO etching process, which adopts the following technical solution:

[0007] A double-sided ITO etching process comprises the following steps:

[0008] S1, back side covering protective layer: coating the back side of the substrate with ITO layer on both sides with a protective layer;

[0009] S2. Apply photosensitive adhesive on the front: Place the side of the substrate with the protective layer on the workbench and apply photosensitive adhesive on the front of the substrate;

[0010] S3, first exposure: move the substrate coated with the photosensitive adhesive into the exposure machine, with the front side facing up, and use a mask and ultraviolet light to expose the photosensitive adhesive on the front side of the substrate;

[0011] S4, first development: the substrate is placed in a developer for development, the exposed photosensitive resin on the front side of the substrate is dissolved by the developer, leaving the unexposed photosensitive resin covering part of the ITO on the substrate, and the ITO part not covered by the photosensitive resin will be exposed, thereby forming a preset pattern on the front side;

[0012] S5, front etching: the substrate is placed in an etching solution for etching, and the ITO portion of the front side of the substrate that is not covered by the photosensitive adhesive is etched away, thereby forming the required ITO pattern on the front side;

[0013] S6, first cleaning: remove the residual photosensitive adhesive on the front side of the substrate and the protective layer on the back side, clean and dry them for later use;

[0014] S7, covering the front side with a protective layer: covering the front side with the ITO pattern formed on the substrate with a protective layer;

[0015] S8, coating photosensitive adhesive on the back: placing the side of the substrate with the protective layer on the workbench, and coating the photosensitive adhesive on the back of the substrate;

[0016] S9, second exposure: move the substrate coated with the photosensitive adhesive into the exposure machine, with the back side facing upward, and use a mask and ultraviolet light to expose the photosensitive adhesive on the back side of the substrate;

[0017] S10, second development: placing the substrate in a developer for development, the exposed photosensitive resin on the back of the substrate is dissolved by the developer, leaving the unexposed photosensitive resin covering part of the ITO on the substrate, and the ITO part not covered by the photosensitive resin will be exposed, thereby forming a preset pattern on the back;

[0018] S11, back etching: placing the substrate into an etching solution for etching, and the ITO portion on the back of the substrate that is not covered by the photosensitive adhesive is etched away, thereby forming the required ITO pattern on the back;

[0019] S12, Second cleaning: remove the residual photosensitive adhesive on the back of the substrate and the protective layer on the front, clean and dry for later use.

[0020] Preferably, the protective layer in step S1 and step S7 is a PVC protective glue formed by printing.

[0021] Preferably, in step S6 and step S12, alkaline solution is first used to remove residual photosensitive adhesive, and then the protective adhesive is peeled off with tape.

[0022] Preferably, in step S6 and step S12, the concentration of the degumming alkali solution is 3±0.1%, the soaking temperature is 45±3° C., and the soaking time is 2 to 5 min.

[0023] Preferably, the protective layer in step S1 and step S7 is formed by printing the protective glue on the substrate by screen printing and then curing it by heating. The printed thickness of the protective glue is 10 to 30 μm, preferably 25 μm.

[0024] Preferably, in step S2 and step S8, the thickness of the photosensitive resin is 1.2-2.0 μm, preferably 1.4 μm.

[0025] Preferably, in step S3 and step S9, the exposure light intensity is 19-25 mW / cm 2 , exposure time 3 to 5 s; preferably the exposure light intensity is 22 mW / cm 2 , exposure time 3.5s.

[0026] Preferably, in step S4 and step S10, the developer is an alkaline solution with a concentration of 0.6±0.1%, and the developing time is 1 to 2 minutes; preferably, the developing time is 1.5 minutes.

[0027] Preferably, in the steps S5 and S11, aqua regia etching is performed at 35±3° C. and the etching time is 1 to 5 minutes.

[0028] Compared with the prior art, the present invention has at least the following beneficial effects:

[0029] The double-sided ITO etching process of the present invention covers the other side of the substrate with a protective layer before coating photosensitive adhesive on one side of the substrate for exposure and development. This not only protects the other side that does not need to be etched, but also makes it unnecessary to coat photosensitive adhesive on both sides for subsequent etching, thereby avoiding contact with the pattern formed by exposure / development during the second coating of photosensitive adhesive and causing contamination, thereby preventing poor circuits during subsequent etching. In addition, since the bottom of the substrate is first covered with the protective layer, even if the workbench is stained with photosensitive adhesive or other solvents, it will not cause contamination to the ITO pattern, thereby reducing the strict requirements of the previous ITO etching process on the cleanliness of the workbench, thereby effectively improving production efficiency and greatly improving the yield rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is the double-sided ITO etching process steps of the prior art;

[0031] Figure 2 This is a structural diagram of a glass plate with ITO layers on both sides of the substrate;

[0032] Figure 3 It is a structural diagram of a glass plate after step S1 of the double-sided ITO etching process of the present invention;

[0033] Figure 4 This is a structural diagram of a glass plate after step S2 of the double-sided ITO etching process of the present invention;

[0034] Figure 5 It is a structural diagram of a glass plate after step S3 of the double-sided ITO etching process of the present invention;

[0035] Figure 6 It is a structural diagram of a glass plate after step S4 of the double-sided ITO etching process of the present invention;

[0036] Figure 7 It is a structural diagram of a glass plate after step S5 of the double-sided ITO etching process of the present invention;

[0037] Figure 8 It is a structural diagram of a glass plate after step S6 of the double-sided ITO etching process of the present invention;

[0038] Fig. 9 It is a structural diagram of a glass plate after step S7 of the double-sided ITO etching process of the present invention;

[0039] Fig.10 It is a structural diagram of a glass plate after step S8 of the double-sided ITO etching process of the present invention;

[0040] Fig.11 It is a structural diagram of a glass plate after step S9 of the double-sided ITO etching process of the present invention;

[0041] Fig.12 This is a structural diagram of a glass plate after step S10 of the double-sided ITO etching process of the present invention;

[0042] Fig.13 This is a structural diagram of a glass plate after step S11 of the double-sided ITO etching process of the present invention;

[0043] Fig.14 It is a structural diagram of a glass plate after step S12 of the double-sided ITO etching process of the present invention;

[0044] Fig.15 This is a quality inspection picture of a product made using traditional technology that has poor point-shaped wiring connections.

[0045] Description of Figure Numbers:

[0046] 1. Substrate; 2. ITO; 3. Protective layer; 4. Photosensitive adhesive; 5. Mask. DETAILED DESCRIPTION

[0047] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0048] like Figure 2-14 As shown, a double-sided ITO etching process includes the following steps:

[0049] S1. Back-covering protective layer: Cover the back of the substrate with ITO layer on both sides with a protective layer; the protective layer is specifically a modified PVC protective glue, which is printed on the substrate by screen printing and then cured by heating at 150°C for 30 minutes. The printed thickness of the protective glue is 10 to 30 μm;

[0050] S2. Apply photosensitive adhesive on the front side: Place the side of the substrate with the protective layer on the workbench of the glue coating machine, and evenly apply photosensitive adhesive on the front side of the substrate through a glue coating roller, and perform a hard film treatment. The thickness of the photosensitive adhesive is 1.2-2.0 μm;

[0051] S3, first exposure: Move the substrate coated with photosensitive adhesive into the exposure machine, with the front side facing up, and use the mask and ultraviolet light to expose the photosensitive adhesive on the front side of the substrate. The exposure light intensity is 19-25mW / cm 2 , exposure time 3 to 5 seconds;

[0052] S4, first development: the substrate is placed in a developer for development, the developer is an alkaline solution with a concentration of 0.6±0.1%, and the development time is 1 to 2 minutes. The exposed photosensitive resin on the front side of the substrate is dissolved by the developer, leaving the unexposed photosensitive resin covering part of the ITO on the substrate, and the ITO part not covered by the photosensitive resin will be exposed, thereby forming a preset pattern on the front side;

[0053] S5, front etching: put the substrate into the etching solution for etching, use aqua regia etching at 35±3℃, the etching time is 1 to 5 minutes, and the etching time is adjusted according to the ITO resistance of different products. The ITO part of the front side of the substrate that is not covered by the photosensitive adhesive is etched away, thereby forming the required ITO pattern on the front side;

[0054] S6, first cleaning: first use alkali solution to remove the residual photosensitive adhesive on the front of the substrate, the concentration of the adhesive removal alkali solution is 3±0.1%, the immersion temperature is 45±3℃, and the immersion time is 2-5min; then use tape to peel off the protective adhesive; finally use deionized water to clean the surface of the substrate and dry it for later use;

[0055] S7, covering the front side with a protective layer: covering the front side of the substrate on which the ITO pattern has been formed with a protective layer;

[0056] S8, coating the back with photosensitive adhesive: placing the side of the substrate with the protective layer on the workbench, evenly coating the front side of the substrate with photosensitive adhesive by means of a coating roller, and performing a hardening treatment, the thickness of the photosensitive adhesive being 1.5 μm;

[0057] S9, second exposure: move the substrate coated with the photosensitive adhesive into the exposure machine, with the back side facing upward, and use a mask and ultraviolet light to expose the photosensitive adhesive on the back side of the substrate, which is the same as the operation in S3;

[0058] S10, second development: placing the substrate in a developer for development, which is the same as the operation in S4, the exposed photosensitive resin on the back of the substrate is dissolved by the developer, leaving the unexposed photosensitive resin covering part of the ITO on the substrate, and the ITO part not covered by the photosensitive resin will be exposed, thereby forming a preset pattern on the back;

[0059] S11, back side etching: placing the substrate into an etching solution for etching, which is the same as the operation in S5, and the ITO part on the back side of the substrate that is not covered by the photosensitive adhesive is etched away, thereby forming the required ITO pattern on the back side;

[0060] S12, second cleaning: remove the residual photosensitive adhesive on the back of the substrate and the protective layer on the front, which is the same as the operation in S6. After cleaning, a product with a double-sided ITO pattern is obtained.

[0061] The PVC protective film used in this solution is 1314F from POLOMA, which is used to temporarily protect the ITO film. It plays a temporary protective role. After the process is completed, it can be easily peeled off with tape, and no residue will be formed on the surface.

[0062] The thickness of the protective glue, the thickness of the photosensitive glue, the exposure parameters, and the development parameters of the process of this scheme are coordinated with each other. If the protective glue is too thin, it will easily wrinkle during acid and alkali soaking and drying, and it will easily break when the film is torn off; if it is too thick, it will affect the thickness and effect of the photosensitive glue coating. If the thickness of the photosensitive glue is too thick, the exposure time will be longer, and the resolution will be reduced (the thin lines will differ greatly from the design value after exposure); if the photosensitive glue is too thin, it will be easy to over-exposure and over-development (the lines will be much thinner than the design after exposure and development), or the photosensitive glue will fall off during development. Too high a concentration of the developer will cause the photosensitive glue to over-develop or even fall off. After actual production verification, the printing thickness of the PVC protective glue in steps S1 and S7 is 25μm; in steps S2 and S8, the thickness of the photosensitive glue is 1.4μm; in steps S3 and S9, the exposure light intensity is 22mW / cm 2 , exposure time 3.5s; in step S4 and step S10, the developer is an alkaline solution with a concentration of 0.6±0.1%, and the development time is 1.5min; the process parameters are designed to cooperate with the above specific values ​​to enable the yield rate of double-sided ITO products to reach the highest level.

[0063] Compared with the traditional process, this process has a higher yield rate in actual production. The original process has a pattern formed by exposure / development on the front side when the photosensitive resin is applied to the back side, and the front side is easily contaminated by contact with the coating roller, which in turn causes poor circuits during subsequent etching. The actual production yield rates of products made by the old process and the new process are as follows:

[0064] Product size: 10 inches

[0065] / Old technology New Technology Yield 70％ 90％

[0066] There are three main types of product defects: dirt, dotted wiring and silver paste disconnection. Among them, dirt is mainly caused by insufficient cleanliness in the operating environment, dotted wiring is mainly caused by poor control during exposure, development or etching, and silver paste disconnection is mainly caused by the silver paste printing process or the quality of the silver paste itself. The larger the product size, the greater the impact on the yield rate. According to the actual production statistics of 10-inch products, the main types of defects of the old process are dirt and dotted wiring. See Fig.15 .

[0067] Compared with the old process, the new process of this scheme has the following advantages:

[0068] 1. The yellow room production process is smoother. After exposure and development, there is no need to apply photosensitive resin for the second time and then etch. Instead, exposure-development-etching-stripping are carried out in sequence, which improves production efficiency.

[0069] 2. The protective glue is printed first, which will not cause pollution to the photosensitive glue pattern, thus eliminating the problem of poor point connection of product routing.

[0070] 3. The protective glue always isolates the bottom of the product from the operating table to prevent the ITO or substrate from being contaminated due to the decrease in the cleanliness of the operating table, thereby better preventing defective products caused by dirt;

[0071] 4. In the old process, during the development and exposure process on the top of the substrate, ultraviolet light will irradiate the photosensitive resin at the bottom edge of the substrate, causing the photosensitive resin at the bottom edge to develop and dissolve, and the exposed ITO will not be protected from corrosion. However, the process of this solution uses a protective glue that will not dissolve after exposure and development, thereby ensuring that the edge of the pattern will not be corroded, improving the yield rate. The only defective type of the new process is a small amount of silver paste breakage, and the yield rate is improved by about 20% compared with the old process.

[0072] The technical solution provided by the present invention is introduced in detail above. Specific examples are used in this article to illustrate the principle and implementation mode of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation mode and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A double-sided ITO etching process, characterized in that: The steps include: S1, back side covering protective layer: coating the back side of the substrate with ITO layer on both sides with a protective layer; S2. Apply photosensitive adhesive on the front: Place the side of the substrate with the protective layer on the workbench and apply photosensitive adhesive on the front of the substrate; S3, first exposure: move the substrate coated with the photosensitive adhesive into the exposure machine, with the front side facing up, and use a mask and ultraviolet light to expose the photosensitive adhesive on the front side of the substrate; S4, first development: the substrate is placed in a developer for development, the exposed photosensitive resin on the front side of the substrate is dissolved by the developer, leaving the unexposed photosensitive resin covering part of the ITO on the substrate, and the ITO part not covered by the photosensitive resin will be exposed, thereby forming a preset pattern on the front side; S5, front etching: the substrate is placed in an etching solution for etching, and the ITO portion of the front side of the substrate that is not covered by the photosensitive adhesive is etched away, thereby forming the required ITO pattern on the front side; S6, first cleaning: remove the residual photosensitive adhesive on the front side of the substrate and the protective layer on the back side, clean and dry them for later use; S7, covering the front side with a protective layer: covering the front side with the ITO pattern formed on the substrate with a protective layer; S8, coating photosensitive adhesive on the back: placing the side of the substrate with the protective layer on the workbench, and coating the photosensitive adhesive on the back of the substrate; S9, second exposure: move the substrate coated with the photosensitive adhesive into the exposure machine, with the back side facing upward, and use a mask and ultraviolet light to expose the photosensitive adhesive on the back side of the substrate; S10, second development: placing the substrate in a developer for development, the exposed photosensitive resin on the back of the substrate is dissolved by the developer, leaving the unexposed photosensitive resin covering part of the ITO on the substrate, and the ITO part not covered by the photosensitive resin will be exposed, thereby forming a preset pattern on the back; S11, back etching: placing the substrate into an etching solution for etching, and the ITO portion on the back of the substrate that is not covered by the photosensitive adhesive is etched away, thereby forming the required ITO pattern on the back; S12, Second cleaning: remove the residual photosensitive adhesive on the back of the substrate and the protective layer on the front, clean and dry for later use.

2. The double-sided ITO etching process according to claim 1, characterized in that: The protective layer in step S1 and step S7 is a PVC protective glue formed by printing.

3. The double-sided ITO etching process according to claim 2, characterized in that: In the step S6 and the step S12, the residual photosensitive adhesive is firstly removed by using alkaline solution, and then the protective adhesive is peeled off by using adhesive tape.

4. The double-sided ITO etching process according to claim 3, characterized in that: In the step S6 and step S12, the concentration of the degumming alkali solution is 3±0.1%, the soaking temperature is 45±3° C., and the soaking time is 2 to 5 minutes.

5. The double-sided ITO etching process according to claim 4, characterized in that: The protective layer in step S1 and step S7 is formed by printing the protective glue on the substrate by screen printing and then curing it by heating. The printing thickness of the protective glue is 10 to 30 μm.

6. The double-sided ITO etching process according to claim 1, characterized in that: In the step S2 and the step S8, the thickness of the photosensitive adhesive is 1.2-2.0 μm.

7. The double-sided ITO etching process according to claim 1, characterized in that: In step S3 and step S9, the exposure light intensity is 19-25 mW / cm 2 , exposure time 3 to 5 seconds.

8. The double-sided ITO etching process according to claim 1, characterized in that: In the step S4 and step S10, the developer is an alkaline solution with a concentration of 0.6±0.1%, and the developing time is 1 to 2 minutes.

9. The double-sided ITO etching process according to claim 1, characterized in that: In the steps S5 and S11, aqua regia etching is performed at 35±3° C. for 1 to 5 minutes.

10. The double-sided ITO etching process according to claim 4, characterized in that: The protective layer in step S1 and step S7 is formed by printing the protective glue on the substrate by screen printing and then curing by heating. The printing thickness of the protective glue is 25 μm. In the step S2 and step S8, the thickness of the photosensitive adhesive is 1.4 μm; In step S3 and step S9, the exposure light intensity is 22 mW / cm 2 , exposure time 3.5s; In the step S4 and step S10, the developer is an alkaline solution with a concentration of 0.6±0.1%, and the developing time is 1.5 minutes.

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