A polyimide screen having a reinforcing layer fixed to the surface thereof and a method for manufacturing the same

Abstract

The application discloses a polyimide screen with a reinforcing layer fixed on the surface and a preparation method thereof, and belongs to the technical field of screen printing screen manufacturing, and has the technical scheme as follows: the polyimide screen with the reinforcing layer fixed on the surface comprises a polyimide screen body, a titanium transition layer fixed on the polyimide screen body through gas deposition and a titanium-doped amorphous carbon composite layer deposited on the titanium transition layer; the titanium transition layer is deposited on the polyimide screen body as a buffer layer, and the titanium-doped amorphous carbon composite layer is deposited on the titanium transition layer, so that the hardness and wear resistance of the screen are effectively improved.

Description

Technical Field

[0001] This invention relates to the field of screen printing stencil manufacturing technology, and in particular to a polyimide stencil with a reinforcing layer fixed on its surface and its preparation method. Background Technology

[0002] In the precision printing and electronics manufacturing industries, screen printing stencils, as one of the core molds, play a crucial role in the industry's development. With the continuous advancement of these industries, the performance requirements for screen printing stencils are also increasing. The quality and performance of the stencil directly affect the printing accuracy and efficiency, thus impacting product quality and production efficiency. Among numerous stencil materials, polyimide, with its excellent thermal stability, flexibility, and mechanical strength, is widely used in the manufacture of screen printing stencils, bringing numerous conveniences and advantages to the industry's development.

[0003] In the past, the treatment of screen printing stencils generally involved improving the material itself. However, due to the inherent characteristics of polyimide, such as low surface energy and strong chemical inertness, it is difficult to significantly improve the stencil's performance through conventional material modification methods. Attempts have been made to improve stencil performance through coating processes; however, the adhesion between these coatings and the polyimide stencil is often unsatisfactory. Meanwhile, some have focused on optimizing the stencil's structural design, but due to issues such as insufficient nano-hardness in polyimide, these improvements have failed to achieve satisfactory results in practical applications.

[0004] Existing polyimide screen printing plates have significant defects. Due to the insufficient nano-hardness of polyimide material, the screen is prone to wear during long-term use, leading to increased line width or even breakage, severely affecting printing accuracy. Furthermore, the adhesion between existing polyimide screens and functional coatings is poor, causing the coatings to peel off easily during use, further reducing the screen's lifespan and printing quality. Summary of the Invention

[0005] To address the problems in the prior art, this invention provides a polyimide screen with a reinforcing layer fixed on its surface and a method for preparing the same. This invention effectively improves the hardness and wear resistance of the screen by depositing a titanium transition layer as a buffer layer on the polyimide screen body and then depositing a titanium-doped amorphous carbon composite layer on the titanium transition layer.

[0006] The first aspect of the present invention is to provide a polyimide screen with a reinforcing layer fixed on its surface, using the following technical solution:

[0007] A polyimide screen with a reinforcing layer fixed on its surface includes a polyimide screen body, a titanium transition layer fixed on the polyimide screen body by vapor deposition, and a titanium-doped amorphous carbon composite layer deposited on the titanium transition layer.

[0008] By adopting the above technical solution, a titanium transition layer is vapor-deposited on the polyimide screen printing substrate. The titanium transition layer and the polyimide screen printing substrate have good bonding performance. At the same time, due to the good toughness and ductility of the titanium transition layer, as well as its ability to form a strong chemical bond with the titanium-doped amorphous carbon composite layer, the thermal and mechanical stress between the polyimide screen printing substrate and the titanium-doped amorphous carbon composite layer can be buffered, thereby enhancing the bonding force between the polyimide screen printing substrate and the titanium-doped amorphous carbon composite layer and preventing coating peeling. In addition, the titanium transition layer itself has a certain degree of nano-hardness, and its combination with the titanium-doped amorphous carbon composite layer effectively improves the nano-hardness of the polyimide screen printing, reduces wear during long-term use, avoids line width increase or breakage, and improves printing accuracy.

[0009] In a preferred embodiment, the thickness of the titanium transition layer is 50-200 nm.

[0010] By adopting the above technical solution, a titanium transition layer with a thickness of 50-200nm is set on the polyimide mesh substrate, which can enhance the bonding force between the polyimide mesh substrate and the titanium-doped amorphous carbon composite layer and reduce the peeling of the coating.

[0011] In a preferred embodiment, the thickness of the titanium-doped amorphous carbon composite layer is 0.05-3 μm.

[0012] By adopting the above technical solution and setting the thickness of the titanium-doped amorphous carbon composite layer to 0.05-3μm, the wear resistance of the screen can be effectively enhanced, the wear of the screen during long-term use can be reduced, and the occurrence of increased line width or damage can be avoided, thereby significantly improving the service life of the screen and ensuring printing accuracy.

[0013] In a preferred embodiment, the atomic percentage content of titanium in the titanium-doped amorphous carbon composite layer is 2.8-18%.

[0014] A second aspect of the present invention is to provide a method for preparing a polyimide screen with a reinforcing layer fixed on its surface, comprising the following steps:

[0015] S1. The polyimide mesh body is subjected to plasma pretreatment;

[0016] S2. A titanium transition layer is deposited on the surface of the pretreated polyimide mesh using a physical vapor deposition process.

[0017] S3. A titanium-doped amorphous carbon composite layer is deposited on the surface of the titanium transition layer using a combination of physical vapor deposition and plasma-enhanced chemical vapor deposition.

[0018] By adopting the above technical solution, plasma pretreatment of the polyimide mesh not only removes surface contaminants and increases surface roughness, but also introduces polar functional groups to increase the bonding force between the polyimide mesh and the titanium transition layer. Furthermore, the addition of the titanium transition layer not only enhances the bonding strength between the titanium-doped amorphous carbon composite layer and the polyimide mesh, but also effectively improves the overall nano-hardness and wear resistance of the polyimide mesh, thus effectively extending the service life of the polyimide mesh.

[0019] In a preferred embodiment, the plasma treatment gas in step S1 is one or both of argon and oxygen.

[0020] In a preferred embodiment, the physical vapor deposition process parameters in step S2 are: argon flow rate of 40 sccm, titanium target sputtering power of 1.0-2.0 kW, and deposition time of 2-5 min.

[0021] In a preferred embodiment, the physical vapor deposition process parameters in step S3 are: titanium target sputtering power of 1.5 kW and carbon source gas flow rate of 12-82 sccm; the plasma-enhanced chemical vapor deposition process parameters are: substrate bias adjusted to -100 V and deposition time of 2-45 min.

[0022] In a preferred embodiment, the carbon source gas is acetylene.

[0023] In summary, the present invention has the following beneficial effects:

[0024] This application introduces a titanium transition layer and a titanium-doped amorphous carbon composite layer onto the polyimide screen printing body, thereby increasing the nano-hardness of the polyimide screen printing body to greater than 15 GPa and enhancing the surface rigidity of the polyimide screen printing body. This results in better dimensional stability of the printed image during the printing process, which is far superior to that of the untreated polyimide screen printing body. Furthermore, the combination of the titanium transition layer and the titanium-doped amorphous carbon composite layer can reduce the surface friction coefficient of the polyimide screen printing body to less than 0.15, thereby reducing frictional resistance during printing, improving printing efficiency, effectively resisting wear of the polyimide screen printing body, extending the service life of the screen printing body, and ultimately reducing production costs. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to embodiments. All details not specifically stated herein are based on conventional conditions or conditions recommended by the manufacturer. All reagents and instruments, unless otherwise stated below, are commercially available conventional reagent products.

[0026] Example 1

[0027] A method for preparing a polyimide screen with a reinforcing layer fixed on its surface includes the following steps:

[0028] S1. Pretreatment: The polyimide mesh is placed in the vacuum chamber of a co-deposition apparatus consisting of physical vapor deposition and plasma-enhanced chemical vapor deposition, and the vacuum is evacuated to 5 × 10⁻⁶. ﹣3 Pa, argon gas is introduced at a flow rate of 50 sccm, and glow discharge is generated under a bias voltage of -300V to perform plasma cleaning on the surface of the polyimide screen for 10 min;

[0029] S2. Deposition of titanium transition layer: A titanium transition layer is deposited on the surface of the pretreated polyimide mesh using a physical vapor deposition process. Specifically, DC magnetron sputtering is used with a pure titanium target (99.99%) as the target material, an argon flow rate of 40 sccm, a sputtering power of 1.0 kW, and a deposition time of 5 min to form a pure titanium layer of about 100 nm thick on the surface of the polyimide mesh.

[0030] S3. A titanium-doped amorphous carbon composite layer was deposited on the surface of the titanium transition layer using a combination of physical vapor deposition and plasma-enhanced chemical vapor deposition. Specifically, the titanium target sputtering power was 1.5 kW, and acetylene gas was introduced as the carbon source at a flow rate of 30 sccm. Carbon plasma was excited by plasma-enhanced chemical vapor deposition, the substrate bias was adjusted to -100 V, and the deposition time was 30 min, resulting in a titanium-doped amorphous carbon composite layer with a thickness of 2 μm and an atomic percentage content of 7.6% titanium.

[0031] Example 2

[0032] A method for preparing a polyimide screen with a reinforcing layer fixed on its surface includes the following steps:

[0033] S1. Pretreatment: The polyimide mesh is placed in the vacuum chamber of a co-deposition apparatus consisting of physical vapor deposition and plasma-enhanced chemical vapor deposition, and the vacuum is evacuated to 5 × 10⁻⁶. ﹣3 Pa, argon gas is introduced at a flow rate of 50 sccm, and glow discharge is generated under a bias voltage of -300V to perform plasma cleaning on the surface of the polyimide screen for 10 min;

[0034] S2. Deposition of Titanium Transition Layer: A titanium transition layer is deposited on the surface of the pretreated polyimide mesh using a physical vapor deposition process. Specifically, DC magnetron sputtering is used with a pure titanium target (99.99%) as the target material, an argon flow rate of 40 sccm, a sputtering power of 1.0 kW, and a deposition time of 2.5 min to form a pure titanium layer of approximately 50 nm thickness on the surface of the polyimide mesh.

[0035] S3. A titanium-doped amorphous carbon composite layer was deposited on the surface of the titanium transition layer using a combination of physical vapor deposition and plasma-enhanced chemical vapor deposition. Specifically, the titanium target sputtering power was 1.5 kW, and acetylene gas was introduced as the carbon source at a flow rate of 81 sccm. Carbon plasma was excited by plasma-enhanced chemical vapor deposition, the substrate bias was adjusted to -100 V, and the deposition time was 2 min, resulting in a titanium-doped amorphous carbon composite layer with a thickness of 0.05 μm and an atomic percentage content of 2.8% titanium.

[0036] Example 3

[0037] A method for preparing a polyimide screen with a reinforcing layer fixed on its surface includes the following steps:

[0038] S1. Pretreatment: The polyimide mesh is placed in the vacuum chamber of a co-deposition apparatus consisting of physical vapor deposition and plasma-enhanced chemical vapor deposition, and the vacuum is evacuated to 5 × 10⁻⁶. ﹣3 Pa, argon gas is introduced at a flow rate of 50 sccm, and glow discharge is generated under a bias voltage of -300V to perform plasma cleaning on the surface of the polyimide screen for 10 min;

[0039] S2. Deposition of titanium transition layer: A titanium transition layer is deposited on the surface of the pretreated polyimide mesh using a physical vapor deposition process. Specifically, DC magnetron sputtering is used with a pure titanium target (99.99%) as the target material, an argon flow rate of 40 sccm, a sputtering power of 1.5 kW, and a deposition time of 5 min to form a pure titanium layer of approximately 150 nm thickness on the surface of the polyimide mesh.

[0040] S3. A titanium-doped amorphous carbon composite layer was deposited on the surface of the titanium transition layer using a combination of physical vapor deposition and plasma-enhanced chemical vapor deposition. Specifically, the titanium target sputtering power was 1.5 kW, and acetylene gas was introduced as the carbon source at a flow rate of 22.8 sccm. Carbon plasma was excited by plasma-enhanced chemical vapor deposition, the substrate bias was adjusted to -100 V, and the deposition time was 22.5 min, resulting in a titanium-doped amorphous carbon composite layer with a thickness of 1.5 μm and an atomic percentage content of 10% titanium.

[0041] Example 4

[0042] A method for preparing a polyimide screen with a reinforcing layer fixed on its surface includes the following steps:

[0043] S1. Pretreatment: The polyimide mesh is placed in the vacuum chamber of a co-deposition apparatus consisting of physical vapor deposition and plasma-enhanced chemical vapor deposition, and the vacuum is evacuated to 5 × 10⁻⁶. ﹣3Pa, argon gas is introduced at a flow rate of 50 sccm, and glow discharge is generated under a bias voltage of -300V to perform plasma cleaning on the surface of the polyimide screen for 10 min;

[0044] S2. Deposition of titanium transition layer: A titanium transition layer is deposited on the surface of the pretreated polyimide mesh using a physical vapor deposition process. Specifically, DC magnetron sputtering is used with a pure titanium target (99.99%) as the target material, an argon flow rate of 40 sccm, a sputtering power of 2.0 kW, and a deposition time of 5 min to form a pure titanium layer of about 200 nm thick on the surface of the polyimide mesh.

[0045] S3. A titanium-doped amorphous carbon composite layer was deposited on the surface of the titanium transition layer using a combination of physical vapor deposition and plasma-enhanced chemical vapor deposition. Specifically, the titanium target sputtering power was 1.5 kW, and acetylene gas was introduced as the carbon source at a flow rate of 12.7 sccm. Carbon plasma was excited by plasma-enhanced chemical vapor deposition, the substrate bias was adjusted to -100 V, and the deposition time was 45 min, resulting in a titanium-doped amorphous carbon composite layer with a thickness of 3 μm and an atomic percentage content of 18% titanium.

[0046] Comparative Example 1

[0047] A method for preparing a polyimide screen with a surface-fixed reinforcing layer differs from Example 1 in that step S2 is omitted, and a titanium-doped amorphous carbon composite layer is directly deposited on the polyimide screen after plasma pretreatment. The process parameters are the same as those in Example 1.

[0048] Comparative Example 2

[0049] A method for preparing a polyimide screen with a reinforcing layer fixed on its surface differs from Example 1 in that, in step S2, the deposition time is 1.5 min, the thickness of the titanium transition layer is 30 nm, and other process parameters are the same as in Example 1.

[0050] Comparative Example 3

[0051] A method for preparing a polyimide screen with a reinforcing layer fixed on its surface differs from Example 1 in that, in step S3, the deposition time is 0.15 min, and the thickness of the titanium-doped amorphous carbon composite layer is 0.01 μm. Other process parameters are the same as in Example 1.

[0052] Performance testing

[0053] The nano-hardness and coefficient of friction of the polyimide screens with reinforced layers obtained in the above embodiments and comparative examples were tested, and the test results are shown in Table 1.

[0054] The testing conditions for nanohardness are as follows: hardness is measured using a microhardness tester, with a loading rate of 10 mN / min, an unloading rate of 10 mN / min, an indentation depth of 50 nm, and a dwell time of the indenter after reaching the set indentation depth of 10 s. Multiple points are tested for each sample, and the average value is calculated to obtain the nanohardness.

[0055] The friction coefficient was tested under the following conditions: the steel ball material was 9Cr18, the steel ball diameter was 8mm, the steel ball was fixed, the load was 2N, the reciprocating distance was 10.2mm, the reciprocating speed was 100 times / min, the steel ball was fixed, and the sample stage made reciprocating motion.

[0056] Table 1. Performance Test Results of Polyimide Screen Printing

[0057] project Nanohardness / GPa coefficient of friction Example 1 17.5 0.08 Example 2 18.2 0.04 Example 3 16.2 0.10 Example 4 15.1 0.14 Comparative Example 1 8.2 0.25 Comparative Example 2 13.2 0.18 Comparative Example 3 4.2 0.31

[0058] Based on the test results in Table 1:

[0059] As can be seen from the test results of Examples 1-4 of this application, as the titanium atom content in the titanium-doped amorphous carbon composite layer increases, the friction coefficient also increases. This is because when the titanium content is relatively low, the hardness of the reinforcing layer is equal to that of the amorphous carbon, and the friction coefficient is also low. When the titanium content increases, the hardness decreases, and the friction coefficient increases significantly. Therefore, when the titanium content is controlled within the range of 2.8-18%, the hardness of the reinforcing layer can be guaranteed, and the wear resistance of the polyimide screen can also be improved.

[0060] Compared with Example 1, when the titanium transition layer was missing, the hardness of the polyimide screen with the reinforced layer obtained in Comparative Example 1 was significantly reduced and the coefficient of friction was significantly increased. This is because the titanium transition layer can effectively buffer the huge difference in mechanical properties between the substrate and the hard coating, avoiding the brittle and hard coating from bending and breaking directly on the soft polyimide screen substrate during indentation testing. At the same time, the lack of the transition layer also means that more defects are easily formed at the interface, thus significantly reducing the hardness of the screen obtained in Comparative Example 1.

[0061] Compared with Example 1, Comparative Example 2 showed that after the thickness of the titanium transition layer was reduced, the stress buffering effect between the hard coating and the flexible polyimide was weakened. The substrate was more likely to undergo plastic deformation during the indentation test, resulting in a decrease in hardness. Furthermore, the coefficient of friction of the coating increased significantly during the reciprocating friction process.

[0062] Compared with Example 1, when the thickness of the composite layer in Comparative Example 3 is 0.01 μm, the hardness is significantly reduced. During the reciprocating friction process, the composite layer is easily worn through, resulting in peeling. Therefore, when the thickness of the composite layer is above 0.05 μm, the hardness of the composite layer can be guaranteed, and the wear resistance of the composite layer can also be guaranteed, thereby significantly improving the service life of the polyimide screen.

[0063] The embodiments described herein are merely illustrative of preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A polyimide screen with a reinforcing layer fixed to its surface, characterized in that: It includes a polyimide mesh body, a titanium transition layer fixed on the polyimide mesh body by vapor deposition, and a titanium-doped amorphous carbon composite layer deposited on the titanium transition layer.

2. The polyimide screen with a reinforcing layer fixed on its surface according to claim 1, characterized in that: The thickness of the titanium transition layer is 50-200 nm.

3. The polyimide screen with a reinforcing layer fixed on its surface according to claim 1, characterized in that: The thickness of the titanium-doped amorphous carbon composite layer is 0.05-3 μm.

4. A polyimide screen with a reinforcing layer fixed on its surface according to claim 1, characterized in that: The titanium-doped amorphous carbon composite layer contains 2.8-18% titanium atoms.

5. A method for preparing a polyimide screen with a reinforcing layer fixed on its surface according to any one of claims 1-4, characterized in that, Includes the following steps: S1. The polyimide mesh body is subjected to plasma pretreatment; S2. A titanium transition layer is deposited on the surface of the pretreated polyimide mesh using a physical vapor deposition process. S3. A titanium-doped amorphous carbon composite layer is deposited on the surface of the titanium transition layer using a combination of physical vapor deposition and plasma-enhanced chemical vapor deposition.

6. The method for preparing a polyimide screen with a reinforcing layer fixed on its surface according to claim 5, characterized in that: The plasma processing gas in step S1 is one or both of argon and oxygen.

7. The method for preparing a polyimide screen with a reinforcing layer fixed on its surface according to claim 5, characterized in that: The physical vapor deposition process parameters in step S2 are: argon flow rate of 40 sccm, titanium target sputtering power of 1.0-2.0 kW, and deposition time of 2-5 min.

8. The method for preparing a polyimide screen with a reinforcing layer fixed on its surface according to claim 5, characterized in that: The physical vapor deposition process parameters in step S3 are as follows: titanium target sputtering power is 1.5 kW, and carbon source gas flow rate is 12-82 sccm; the plasma-enhanced chemical vapor deposition process parameters are as follows: substrate bias voltage is adjusted to -100 V; and deposition time is 2-45 min.

9. The method for preparing a polyimide screen with a reinforcing layer fixed on its surface according to claim 8, characterized in that: The carbon source gas is acetylene.