Thin film circuit manufacturing method using green oil as photoresist
By using green oil as a photoresist to replace traditional photoresist, and combining printing, curing, exposure, and development processes, the problems of high cost and defects are solved, enabling low-cost, high-precision thin-film circuit fabrication, suitable for products with linewidths of 0.1mm ± 0.01mm and above.
Patent Information
- Application Number
- CN202511477857.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-16
- Publication Date
- 2026-01-13
AI Technical Summary
Existing technologies for fabricating thin-film circuits with linewidths of 0.1mm ± 0.01mm and above use photoresist processes, which are costly and prone to defects such as photoresist breakage and peeling, making it difficult to meet the requirements of low cost and high precision.
By using green oil instead of photoresist as the photoresist, and through processes such as printing, curing, exposure, and development, and in conjunction with a high-power solder mask exposure machine, thin-film circuit products with a linewidth accuracy of 0.1mm ± 0.01mm and above can be manufactured.
It reduces the manufacturing cost of thin-film circuits by about 20%, improves the photosensitivity and corrosion resistance of the green oil, ensures the straightness of the line edges, and is suitable for mass production of high-precision thin-film circuit products.
Smart Images
Figure CN121335003A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of PCB board preparation, and particularly relates to a thin film circuit manufacturing method using green oil as a photoresist. BACKGROUND
[0002] A conventional thin film process of a hybrid integrated circuit (HIC) is to plant a required metal layer on a clean ceramic substrate by using a vacuum deposition process such as evaporation and sputtering, and then to manufacture a pattern by using a photoresist as a photoresist agent and adopting a quartz glass chrome plate through processes such as exposure, development, and electroplating with photoresist, as shown in the following formula (I). Figure 1
[0003] The high-cost process of the thin film photoresist as a photoresist agent is mainly due to special performance requirements, strict standards, and low production scale in the military field. In the field of military thin film circuits, the photoresist process can be mainly used to produce high-precision circuits with a line width precision of 15 μm. However, at least 40% of products on the market, such as DPC copper circuit products, thin film heat sinks, signal connection plates, and high-power heat dissipation substrates, have a line width and a line spacing of more than 0.1 mm ± 0.01 mm. If the photoresist process route is used again, the cost pressure will be very large, and the competitiveness will be gradually lost in the increasingly fierce and cruel market. SUMMARY
[0004] The present application is to solve the problems of the prior art, and aims to provide a thin film circuit manufacturing method using green oil as a photoresist agent. By using the present application, the green oil is used to replace the photoresist as a photoresist agent, and the thin film circuit products with a line width precision of 0.1 mm ± 0.01 mm and above can be manufactured by using a low-cost process route.
[0005] The present application is achieved by the following technical solutions:
[0006] A thin film circuit manufacturing method using green oil as a photoresist agent includes the step of printing green oil on a substrate to replace photoresist, so as to manufacture thin film circuit products with a line width precision of 0.1 mm ± 0.01 mm and above.
[0007] Compared to existing technologies, using photoresist in the fabrication of thin-film circuit patterns of 0.1mm ± 0.01mm and above would result in significant cost pressures. Furthermore, traditional photoresist fabrication methods, involving coating, pre-baking, exposure, and development, are prone to defects such as photoresist breakage and peeling during electroplating due to the thinness of the photoresist (approximately 5-8µm). This invention provides a method for fabricating thin-film circuits using solder mask (SMD) as the photoresist. By replacing photoresist with SMD, this method achieves a linewidth accuracy of 0.1mm ± 0.01mm and above using a low-cost process. The SMD used in this method is primarily applied to solder mask fabrication in printed circuit boards (PCBs). It is essentially a liquid photosensitive polymer, and its main function is to provide solder protection during assembly processes. However, a closer look at the characteristics of green oil reveals that its main components are epoxy resin matrix + photoinitiator (such as benzophenone) + green pigment (chromium oxide). Its photosensitivity mechanism involves a cross-linking reaction after exposure to ultraviolet light (wavelength 365nm). Unexposed areas can be removed by development with a minimum of 0.6% sodium carbonate solution. Its maximum resolution is 0.05mm, and its cost is only one percent of that of photoresist. A comparison of the characteristics of green oil and photoresist is shown in the table below.
[0008] Properties Green oil Thin film photoresist Conventional function Solder resist protection (oxidation proof / insulation) Circuit patterning Application field PCB manufacturing, consumer electronics Thin film circuit lithography Thickness range 15-35 pm 1-7 pm Temperature resistance 180℃ 230℃ Cost 80-100 yuan / kg 15000 yuan / gallon Whether used to make patterns Not yet developed in the market Yes, mature technology Equipment matching Solder resist exposure machine UV high-precision exposure machine
[0009] Compared to traditional photoresist, green solder mask (SSD) costs approximately one percent of the production cost. Furthermore, as a photoresist, SSD can be used with a high-power solder resist exposure machine when fabricating thin-film circuit patterns of 0.1mm ± 0.01mm and larger, with exposure conditions of 6kW and 30s. In contrast, photoresist requires a high-precision UV exposure machine with an exposure energy of 200mw / cm². 2 The time is 20s ± 1s. Typically, the price of a solder resist exposure machine is about 1 / 3 of that of a UV exposure machine, resulting in an overall cost reduction of over 20%.
[0010] Further optimization involves a thin-film circuit fabrication method using green oil as a photoresist, comprising the following specific steps:
[0011] S1: Perform plasma treatment on the surface of the substrate after cleaning and sputtering;
[0012] S2: Place the processed substrate into a printing press and uniformly print a layer of green oil on the surface of the substrate;
[0013] S3: After printing, bake to fully cure the green oil;
[0014] S4: After curing, the green oil in the graphic area is exposed and decomposed by an exposure machine, and then developed by a sodium carbonate solution.
[0015] S5: Subsequently, a green oil hardening film is applied, followed by green oil electroplating.
[0016] S6: After electroplating, a metal layer is sputtered for pattern protection, and after sputtering, the green oil in the cured non-pattern areas is removed by soaking in sodium carbonate solution;
[0017] S7: Finally, complete the wet etching process.
[0018] In this solution, the green oil, as a photoresist, exhibits more stable photosensitive properties after printing, curing, exposure, development, and hardening processes. Because its printing thickness is approximately 15-35μm, it provides greater corrosion resistance and electroplating resistance during electroplating and metal etching processes with green oil, and the green oil also plays a protective role. In contrast, photoresist, as a photoresist for fabricating thin-film circuits, requires traditional coating, pre-baking, exposure, and development processes. Since photoresist is relatively thin, with a thickness of approximately 5-8μm, it is prone to defects such as breakage and peeling during electroplating.
[0019] In a further optimization, step S1 also includes the following sub-steps:
[0020] When performing plasma treatment on the substrate surface, the substrate needs to be placed in the vacuum environment of the plasma equipment and a certain amount of argon and oxygen are introduced. After ignition under vacuum conditions, the substrate is treated by plasma and left to stand for a certain period of time.
[0021] In a further optimization, in step S2, before printing the green ink, the green ink needs to be mechanically stirred and allowed to stand for a certain period of time.
[0022] For further optimization, in step S2, a 20μm±3μm green oil layer needs to be uniformly printed on the surface of the substrate.
[0023] In a further optimization, step S4 also includes the following sub-steps:
[0024] After development, it is necessary to observe the integrity of the graphic areas not covered by the green oil and the steepness of the lines. If the green oil in non-graphic areas is developed away, it needs to be inspected under a microscope and repaired with a fine brush dipped in green oil.
[0025] For further optimization, the exposure machine is a solder resist exposure machine.
[0026] In a further optimization, in step S5, the electroplated metal is Au, and the surface Au thickness is >3μm.
[0027] In a further optimization, in step S6, the sputtered metal layer is a titanium-tungsten metal layer.
[0028] Further optimization involves printing the green solder mask onto the substrate surface using screen printing. Screen printing the green solder mask as a photoresist offers greater ease of operation, lower equipment requirements, and wider applicability.
[0029] Compared with the prior art, the present invention has the following advantages and beneficial effects:
[0030] 1. This invention provides a method for fabricating thin-film circuits using green oil as a photoresist. By using this method, green oil is used instead of photoresist as the photoresist, and exposure and development are performed using film plates. This method enables the fabrication of thin-film circuit products with a linewidth accuracy of 0.1mm ± 0.01mm or higher using a low-cost process route.
[0031] 2. This invention provides a method for fabricating thin-film circuits using green solder mask as a photoresist. Compared with traditional photoresist, the cost of green solder mask is approximately one percent of that of photoresist. Furthermore, when using green solder mask as a photoresist to fabricate thin-film circuit patterns of 0.1mm ± 0.01mm and larger, a high-power solder resist exposure machine can be used, with exposure conditions of 6kW and an exposure time of 30s. In contrast, photoresist can only be exposed using a high-precision UV exposure machine, with exposure conditions of 200mw / cm². 2 The time is 20s ± 1s. Typically, the price of a solder resist exposure machine is about 1 / 3 of that of a UV exposure machine, resulting in an overall cost reduction of over 20%.
[0032] 3. This invention provides a method for fabricating thin-film circuits using green oil as a photoresist. After printing, curing, exposure, development, and hardening processes, the green oil exhibits more stable photosensitive properties because its printing thickness is approximately 15-35 μm. In electroplating and metal etching processes with green oil, it has better corrosion resistance and electroplating resistance, and the green oil provides better protection. In contrast, using photoresist as a photoresist to fabricate thin-film circuits requires traditional processes such as coating, pre-baking, exposure, and development. Because the photoresist thickness is approximately 5-8 μm, it is relatively thin and prone to defects such as breakage and peeling during electroplating.
[0033] 4. This invention provides a method for fabricating thin-film circuits using green oil as a photoresist, which still maintains the steepness of traditional photoresist line edges. It can be widely used in the fabrication of thin-film circuit products with line width accuracy of 0.1mm±0.01mm and above, and the finished product has mass production capability and high practical performance. Attached Figure Description
[0034] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:
[0035] Figure 1 This is a flowchart of the traditional photoresist process in existing technologies;
[0036] Figure 2 A flowchart of the green oil fabrication process for thin-film circuits provided by this invention;
[0037] Figure 3 The schematic diagram of the thin-film circuit fabrication using green oil provided by this invention;
[0038] Figure 4 This is a design diagram of a filter product in Embodiment 2 of the present invention;
[0039] Figure 5 This is the product engineering layout diagram in Embodiment 2 provided by the present invention;
[0040] Figure 6 This is a product state diagram after pattern electroplating with green oil provided in Embodiment 2 of the present invention;
[0041] Figure 7 The final product drawing provided in Embodiment 2 of the present invention. Detailed Implementation
[0042] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.
[0043] Example 1: This Example 1 provides a method for fabricating thin-film circuits using green oil as a photoresist, such as... Figure 2 and Figure 3 As shown, the process includes printing green oil on a substrate instead of photoresist to produce thin-film circuit products with a linewidth accuracy of 0.1mm ± 0.01mm or higher.
[0044] Compared to existing technologies, using photoresist in the fabrication of thin-film circuit patterns of 0.1mm ± 0.01mm and above would result in significant cost pressures. Furthermore, traditional photoresist fabrication methods, involving coating, pre-baking, exposure, and development, are prone to defects such as photoresist breakage and peeling during electroplating due to the thinness of the photoresist (approximately 5-8µm). This invention provides a method for fabricating thin-film circuits using solder mask (SMD) as the photoresist. By replacing photoresist with SMD, this method achieves a linewidth accuracy of 0.1mm ± 0.01mm and above using a low-cost process. The SMD used in this method is primarily applied to solder mask fabrication in printed circuit boards (PCBs). It is essentially a liquid photosensitive polymer, and its main function is to provide solder protection during assembly processes. However, a closer look at the characteristics of green oil reveals that its main components are epoxy resin matrix + photoinitiator (such as benzophenone) + green pigment (chromium oxide). Its photosensitivity mechanism involves a cross-linking reaction after exposure to ultraviolet light (wavelength 365nm). Unexposed areas can be removed by development with a minimum of 0.6% sodium carbonate solution. Its maximum resolution is 0.05mm, and its cost is only one percent of that of photoresist. A comparison of the characteristics of green oil and photoresist is shown in the table below.
[0045] Properties Green oil Thin film photoresist Conventional function Solder resist protection (oxidation proof / insulation) Circuit patterning Application field PCB manufacturing, consumer electronics Thin film circuit lithography Thickness range 15-35 pm 1-7 pm Temperature resistance 180℃ 230℃ Cost 80-100 yuan / kg 15000 yuan / gallon Whether used to make patterns Not yet developed in the market Yes, mature technology Equipment matching Solder resist exposure machine UV high-precision exposure machine
[0046] Compared to traditional photoresist, green solder mask (SSD) costs approximately one percent of the production cost. Furthermore, as a photoresist, SSD can be used with a high-power solder resist exposure machine when fabricating thin-film circuit patterns of 0.1mm ± 0.01mm and larger, with exposure conditions of 6kW and 30s. In contrast, photoresist requires a high-precision UV exposure machine with an exposure energy of 200mw / cm². 2 The time is 20s ± 1s. Typically, the price of a solder resist exposure machine is about 1 / 3 of that of a UV exposure machine, resulting in an overall cost reduction of over 20%.
[0047] Example 2: Based on Example 1, Example 2 provides a specific implementation step for a thin-film circuit fabrication method using green oil as a photoresist, such as... Figure 2-Figure 7 As shown, it includes:
[0048] The detailed fabrication method for thin-film circuits using green solder mask is as follows:
[0049] 1. First, the cleaned and sputtered substrate is subjected to plasma treatment. The treatment process is 40kHz plasma, with 100sccm of argon and 50sccm of oxygen. After ignition under vacuum conditions, the plasma treatment substrate is allowed to act for 10 minutes.
[0050] 2. Take out the green oil and mechanically stir it for 10 minutes, then let it stand for 20 minutes. The purpose is to alleviate the air bubbles generated in the subsequent green oil brushing process. Then, put the plasma-treated ceramic substrate into the printing machine and uniformly print a 20μm±3μm green oil layer on the substrate surface. The uniformity of the green oil layer will affect the line width production of the subsequent exposure and development process. This step is a key item.
[0051] 3. After the green oil is applied, bake it at 120℃ for 10 minutes to fully cure it.
[0052] 4. After aligning the mask (film plate) used to make the product, perform energy exposure using a high-power exposure machine of about 6kw. The purpose is to decompose the green oil exposure of the graphic part and then develop it away with a 0.6% sodium carbonate solution.
[0053] 5. At this point, observe the integrity of the graphic areas not covered by the green oil after development and the steepness of the lines. If any non-graphic areas are covered by the green oil after development, they need to be manually inspected under a 40x microscope and repaired with a fine brush dipped in green oil.
[0054] 6. After the repair is completed, perform a hardening process at 150℃ for 20 minutes. After the hardening process, perform electroplating with green oil to complete the pattern electroplating with Au. The surface Au thickness is >3μm.
[0055] 7. Complete the sputtering with green oil to sputter a titanium-tungsten metal layer, protecting the Au surface of the pattern and facilitating subsequent etching.
[0056] 8. Soak in 0.6% sodium carbonate solution for 15 minutes to remove the green oil from the non-graphic areas after curing.
[0057] 9. Complete the wet etching process.
[0058] 10. Inspect the dicing, measure the line width accuracy, and check the adhesion of the pattern, etc.
[0059] Green solder mask is commonly used as a photoresist in the fabrication of solder resist patterns on PCBs. This project uses green solder mask as a photoresist to fabricate thin-film circuits, reducing manufacturing costs by more than 20% while ensuring product reliability. This approach is suitable for the low-cost, mass production of future military HIC products. The schematic diagram of the green solder mask thin-film circuit fabrication principle is as follows: Figure 2 As shown. The key points of the overall production are:
[0060] 1. When using green ink, take out the appropriate amount, mechanically stir for 10 minutes, and let it stand for 20 minutes to minimize air bubbles generated during printing.
[0061] 2. Before printing with green ink, the substrate surface needs to be plasma treated to ensure the adhesion of the green ink.
[0062] 3. The thickness of the green ink printing needs to be guaranteed, generally required to be 20μm±3μm, so that a line width of 0.1mm±0.01mm can be produced.
[0063] 4. After sputtering titanium tungsten, the green oil needs to be completely removed to ensure the quality of non-graphic areas.
[0064] The final thin-film circuit product has a minimum linewidth of 0.105mm, meeting the linewidth accuracy requirement of 0.1mm±0.01mm. The lines are steep, the surface condition of the pattern is excellent, and no green solder mask residue was found in the non-pattern areas, meeting the product performance indicators. The product has good reliability, meets the requirements of the thin-film circuit mass production process, and has high practicality.
[0065] In the above scheme, the application of green solder mask as a photoresist is mainly concentrated in the solder mask production of printed circuit boards (PCBs). It is essentially a liquid photosensitive polymer, and its main function is to protect the solder joints during assembly. However, a closer examination of the characteristics of green solder mask reveals that its main components are epoxy resin matrix + photoinitiator (such as benzophenone) + green pigment (chromium oxide). Its photosensitive mechanism involves a cross-linking reaction after exposure to ultraviolet light (wavelength 365nm). Unexposed areas can be removed by development with a minimum of 0.6% sodium carbonate solution, achieving a maximum resolution of 0.05mm. Therefore, by utilizing this photosensitive property of green solder mask as a photoresist, combined with film plates for exposure and development, a low-cost process can be used to manufacture thin-film circuit products with a linewidth accuracy of 0.1mm ± 0.01mm and above. Compared to traditional photoresist, the production cost of green solder mask is approximately one percent of that of photoresist. Furthermore, as a photoresist, green solder mask can be used with a high-power solder resist exposure machine when fabricating thin-film circuit patterns of 0.1mm ± 0.01mm and larger, with exposure conditions of 6kW and 30s. In contrast, photoresist can only be exposed using a high-precision UV exposure machine, with exposure conditions of 200mw / cm². 2 The time is 20s ± 1s. Typically, the price of a solder resist exposure machine is about 1 / 3 of that of a UV exposure machine, resulting in an overall cost reduction of over 20%.
[0066] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for fabricating a thin-film circuit using oil-based green photoresist, characterized in that, This includes the step of printing green oil on a substrate instead of photoresist to produce thin-film circuit products with a linewidth accuracy of 0.1mm ± 0.01mm or higher.
2. The method for fabricating a thin-film circuit using green oil as a photoresist according to claim 1, characterized in that, The specific steps include the following: S1: Perform plasma treatment on the surface of the substrate after cleaning and sputtering; S2: Place the processed substrate into a printing press and uniformly print a layer of green oil on the surface of the substrate; S3: After printing, bake to fully cure the green oil; S4: After curing, the green oil in the graphic area is exposed and decomposed by an exposure machine, and then developed by a sodium carbonate solution. S5: Subsequently, a green oil hardening film is applied, followed by green oil electroplating. S6: After electroplating, a metal layer is sputtered for pattern protection, and after sputtering, the green oil in the cured non-patterned areas is removed by soaking in sodium carbonate solution; S7: Finally, complete the wet etching process.
3. The method for fabricating a thin-film circuit using green oil as a photoresist according to claim 2, characterized in that, Step S1 further includes the following sub-steps: When performing plasma treatment on the substrate surface, the substrate needs to be placed in the vacuum environment of the plasma equipment and a certain amount of argon and oxygen are introduced. After ignition under vacuum conditions, the substrate is treated by plasma and left to stand for a certain period of time.
4. The method for fabricating a thin-film circuit using green oil as a photoresist according to claim 2, characterized in that, In step S2, before printing the green ink, the green ink needs to be mechanically stirred and left to stand for a certain period of time.
5. The method for fabricating a thin-film circuit using green oil as a photoresist according to claim 2, characterized in that, In step S2, a 20μm±3μm green oil layer needs to be uniformly printed on the surface of the substrate.
6. The method for fabricating a thin-film circuit using green oil as a photoresist according to claim 2, characterized in that, Step S4 further includes the following sub-steps: After development, it is necessary to observe the integrity of the graphic areas not covered by the green oil and the steepness of the lines. If the green oil in non-graphic areas is developed away, it needs to be inspected under a microscope and repaired with a fine brush dipped in green oil.
7. The method for fabricating a thin-film circuit using green oil as a photoresist according to claim 2, characterized in that, The exposure machine is a solder resist exposure machine.
8. The method for fabricating a thin-film circuit using green oil as a photoresist according to claim 2, characterized in that, In step S5, the electroplated metal is Au, and the surface Au thickness is greater than 3 μm.
9. A method for fabricating a thin-film circuit using green oil as a photoresist according to claim 2, characterized in that, In step S6, the sputtered metal layer is a titanium-tungsten metal layer.
10. A method for fabricating a thin-film circuit using green oil as a photoresist according to claim 2, characterized in that, When printing green oil on the surface of the substrate, it is necessary to use screen printing.