Uniform gluing and hot press molding process method based on silk screen

Abstract

The invention discloses a process method based on uniform gluing and hot press molding of a silk screen. The process method comprises the following steps of preparation of a silk screen template, gluing, pre-curing and hot press molding. Manufacturing an opening pattern and a hollow pattern matched with the gluing area of the wafer or the PLP substrate on the silk screen, and fixing the opening pattern and the hollow pattern on the metal frame to obtain a silk screen template; fixing the wafer or the PLP substrate on a vacuum adsorption table, covering the surface of the wafer or the PLP substrate with the screen template in parallel, and blade-coating, stripping, drying and repeating the glue solution along the surface of a screen by adopting a polyurethane scraper or a metal scraper to obtain a glued wafer or PLP substrate; and the glued wafer or PLP substrate is placed in a heating furnace to be subjected to pre-curing treatment and hot pressing, and the hot-pressed wafer or PLP substrate is obtained. According to the process method, a composite process of silk screen gluing and precise hot pressing is adopted, the patterning capacity of silk screen printing is organically combined with the leveling, densifying and adhesive force enhancing capacity of the hot pressing process, and the effect of '1 + 1gt, 2' is achieved.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor manufacturing technology, and specifically relates to a process method based on uniform screen coating and hot pressing. Background Technology

[0002] In the semiconductor manufacturing field, with the continuous improvement of chip integration and the miniaturization and high-density development of packaging forms, wafer and PLP substrate back grinding has become one of the core processes. Back grinding can reduce the thickness of wafers and PLP substrates from the initial 600-700μm to 50-200μm, not only meeting the thickness requirements of advanced packaging forms such as stacked packaging and 3D packaging, but also reducing chip thermal resistance and improving electrical performance. However, during back grinding, the high-speed rotating grinding wheel applies continuous mechanical stress to the back of the wafer and PLP substrate, easily leading to damage such as edge chipping, warping, and cracks. Simultaneously, particulate impurities such as silicon powder generated during grinding may adhere to the surface of the wafer and PLP substrate or intrude into gaps, affecting the stability of subsequent packaging processes and product yield.

[0003] To address the aforementioned issues, a protective adhesive layer must be coated onto the front side (device side) of the wafer and PLP substrate before back grinding, forming a complete protective film. This protective film must possess sufficient mechanical strength, good adhesion, and abrasion resistance to provide reliable mechanical support and surface protection for the substrate during back grinding, preventing damage and contamination. Simultaneously, after back grinding, the protective film must be easily and completely peeled off without leaving any residue, ensuring no impact on the performance of the front-side devices. Therefore, the coating process of the protective adhesive directly determines the thickness uniformity, surface smoothness, adhesion, and pattern compatibility of the protective film, making it a crucial step in ensuring the yield of back grinding on the wafer and PLP substrate.

[0004] Currently, the main coating methods for back-grinding protective adhesives include spin coating, blade / slit coating, and direct thermoforming. Each method has significant limitations. Spin coating has low material utilization, film thickness uniformity errors typically exceed ±10%, and it has stringent requirements on the viscosity range of the adhesive. Blade / slit coating has poor adaptability to non-flat wafers with pre-attached chips, surface height differences, and PLP substrates, easily causing scratches or uneven coating. Direct thermoforming is usually used as a separate step to flatten the pre-coated adhesive layer, but if combined with uneven initial coating, it can lead to localized missing or overflowing adhesive, resulting in defects such as voids and uneven thickness. In addition, there is an ultrasonic spraying technology that can be used for adhesive coating. It atomizes the adhesive into nano-sized particles through high-frequency vibration to achieve uniform spraying and can control the film thickness error within ±5%. However, this technology has limitations such as high equipment cost, narrow adaptability to adhesive viscosity (only applicable to low-viscosity adhesives), and inability to directly achieve integrated molding after coating.

[0005] Existing back-grinding protective adhesive coating processes have significant shortcomings in terms of thick film uniformity, material utilization, adaptability to uneven surfaces, and edge control precision. They cannot fully meet the demands of complex back-grinding scenarios in advanced packaging, such as bumped wafers, large-size wafers and substrates, and fine protection, thus hindering improvements in back-grinding yield and reductions in packaging costs. Therefore, developing a back-grinding protective adhesive coating process that combines high material utilization, uniform thick film formation, precise patterning, high efficiency, and broad adaptability to various wafers and PLP substrates has become an urgent technical problem to be solved in this field. Summary of the Invention

[0006] In view of this, the present invention provides a process method for uniform adhesive coating and hot pressing based on screen printing. This method combines the advantages of high material utilization and high viscosity adaptability of screen printing with the advantages of high flatness and high uniformity of hot pressing, achieving the formation of a uniform adhesive layer with precisely controllable thickness, extremely smooth surface, and no internal defects. The present invention can be used to form adhesive layers with a thickness between 50 and 200 μm, and the thickness difference can be controlled within ≤±3%. The larger the effective coating area compared to the substrate, the better the coating effect. It can be widely used in semiconductor wafers, PLP substrates, liquid crystal display panels, and other processes with high coating requirements and high coating difficulty. In addition, the shape of the screen can be made according to the shape of the substrate, making the application simple and efficient.

[0007] According to one aspect of the present invention, a process method based on screen printing with uniform adhesive coating and hot pressing is provided, comprising the following steps:

[0008] Step 1, Preparation of the screen template: Create opening patterns and cutout patterns on the screen that match the coating area of ​​the wafer or PLP substrate, and fix it on the metal frame to obtain the screen template. Step 2, coating: Fix the wafer or PLP substrate on the vacuum adsorption stage, and cover the surface of the wafer or PLP substrate with the screen template prepared in step 1 in parallel. The length of the adhesive strip is less than the width of the coating area. Use a polyurethane scraper or a metal scraper to scrape the adhesive along the surface of the screen. Peel the screen template vertically upward, dry, and repeat the scraping-peeling operation to obtain the coated wafer or PLP substrate. Step 3, Pre-curing: Place the coated wafer or PLP substrate obtained in Step 2 into a heating furnace for pre-curing treatment to obtain a pre-cured wafer or PLP substrate. Step 4, hot pressing: Place the pre-cured wafer or PLP substrate obtained in step 3 on a hot press and hot press it to obtain the hot-pressed wafer or PLP substrate.

[0009] Based on the above technical solution, the size of the wafer in step 1 is one of 6 inches, 8 inches, and 12 inches; When the wafer size is 6 inches, the wafer diameter is 150mm ± 0.2mm and the thickness is 625μm ± 5μm; When the wafer size is 8 inches, the wafer diameter is 200mm ± 0.2mm and the thickness is 725μm ± 5μm; When the wafer size is 12 inches, the wafer diameter is 300mm ± 0.2mm and the thickness is 775μm ± 5μm; The size of the PLP substrate mentioned in step 1 is one of 300mm×300mm, 510mm×515mm, and 600mm×600mm; The opening pattern in step 1 is either a circle with a diameter 0.5-2 mm smaller than the wafer diameter or a square with a side length 0.5-2 mm smaller than the PLP substrate. The hollowed-out pattern mentioned in step 1 is a circular concentric double-ring composite pattern, a square concentric double-ring composite pattern, etc., and the mesh is square; The wire mesh mentioned in step 1 is a woven mesh of stainless steel wire or polyester wire with a mesh count of 100~500 mesh, of which the fine glue-coated area (functional area) has a mesh count of 300~500 mesh, the thick glue area (edge ​​blank area) has a mesh count of 200~250 mesh, the thickness is 15~100μm, and the opening ratio is 45%~75%.

[0010] Based on the above technical solution, the edge area of ​​the hollowed-out pattern in step 1 is controlled with an accuracy of ±0.01mm; The tension of the wire mesh template mentioned in step 1 is 25~30 N / cm.

[0011] Based on the above technical solution, the levelness error of the vacuum adsorption worktable in step 2 is ≤0.005mm / m; In step 2, the distance between the screen template and the surface of the wafer or PLP substrate is 0.1~0.3mm (i.e., screen distance). The viscosity of the adhesive solution mentioned in step 2 is 500~20000 mPa·s. The higher the mesh number, the lower the viscosity should be.

[0012] Based on the above technical solution, the coating-peeling operation in step 2 is as follows: the adhesive is applied in a linear fashion to the starting position of the squeegee on the screen, the length of the adhesive strip is less than the width of the coating area, and a polyurethane squeegee or metal squeegee is used to uniformly coat the screen surface at a speed of 5~15mm / s, the angle between the squeegee and the screen is 35~90°, and the coating pressure is 0.005~0.02MPa. After the coating is completed, the screen template is peeled vertically upward at a speed of 5~10mm / s, dried at 20~30℃ for 3~5min, and the operation is repeated 2~3 times to obtain the coated wafer or PLP substrate. The length of the adhesive strip is 3-5 mm smaller than the size of the wafer or PLP substrate, and the width of the adhesive coating area is 0.5-2 mm smaller than the size of the wafer or PLP substrate. The wire width of the wire mesh is 20~60μm; The adhesive layer thickness of the coated wafer or PLP substrate is 50~200μm.

[0013] Based on the above technical solution, the pre-curing process in step 3 is as follows: hot air circulation heating is used to place the coated wafer or PLP substrate in a heating oven at 80~100℃ for 5~8 minutes to evaporate some of the solvent in the adhesive, so that the adhesive layer is initially cured and shaped, avoiding the flow and deformation of the adhesive liquid during subsequent hot pressing. The humidity of the cavity during the pre-curing process is 30~50% to prevent water vapor condensation on the surface of the adhesive layer.

[0014] Based on the above technical solution, the hot pressing process in step 4 is as follows: the pre-cured wafer or PLP substrate is placed on the hot pressing mold of the hot press machine and heated to 120-160°C at a heating rate of 5-10°C / min. The mold is then pressed at a pressure of 0.5-2MPa at a uniform speed for 1-2 minutes. During the hot pressing process, a vacuum is simultaneously drawn to make the cavity vacuum degree -100Pa to -50Pa, removing residual air bubbles inside the adhesive layer and enhancing the density of the adhesive layer.

[0015] Beneficial effects (1) This invention discloses a composite process of “screen printing + precision hot pressing”: the patterning ability of screen printing is organically combined with the leveling, densification and enhanced adhesion ability of hot pressing process, achieving the effect of “1+1>2”, and solving the defects of single coating method in wafer and PLP substrate application such as low material utilization, prominent edge effect, poor adaptability of thick film and large-size substrate, poor coverage of complex structure and poor viscosity compatibility of adhesive.

[0016] (2) The technical solution disclosed in this invention significantly improves the uniformity of the adhesive layer: by using customized screen templates and precise scraping control, the thickness error of the adhesive layer is ≤±3%, which is significantly optimized compared with the traditional spin coating method (error ±10% or more) and ultrasonic spraying method (error ±5%). It can also achieve coating without dead angles on wafers and PLP substrates with complex surface structures such as deep trenches and high aspect ratios, solving the problem of blind spots in the adhesive coating of the prior art.

[0017] (3) The material utilization rate of the technical solution disclosed in this invention is greatly improved: the screen coating precisely controls the coating area through the hollow pattern, and the adhesive is applied only in the required area, reducing the material waste rate to less than 10%. Compared with the spin coating method (waste rate of 50%~70%), it can save a lot of materials and significantly reduce production costs.

[0018] (4) The technical solution disclosed in this invention has strong process adaptability and controllable cost: the screen template can be customized according to different substrate specifications and coating requirements. According to the adjustment of the screen mesh number, it can be applied to adhesive liquid with a viscosity range of 500~20000mPa·s, and is used for coating adhesive layers of different thicknesses of 50~200μm. Moreover, the equipment structure is simpler than that of ultrasonic spraying equipment, and the investment cost is reduced by 30%~50%. At the same time, the integrated process reduces the space occupied by the equipment and the process flow time, and the processing efficiency is increased by more than 20%.

[0019] (5) After hot pressing, the total thickness change of the substrate adhesive film is reduced by less than 10 μm, which is more than 50% higher than the total thickness change of other coating methods. It is more suitable for process requirements. Attached Figure Description

[0020] Figure 1 A schematic diagram of a screen coating device and a microporous ceramic vacuum adsorption base (where 101: microporous ceramic vacuum adsorption base, 200: screen coating device, 201: screen of screen coating device, 202: coating pattern of screen coating). Figure 2 This is a schematic diagram of a hot press (where 301: hot press servo electric cylinder, 302: hot press movable plate, 303: lower mold heating plate and mold, 304: upper mold heating plate and mold, 305: hot press fixed plate, 306: hot press top plate). Figure 3 This is a schematic diagram of screen coating (where 101: microporous ceramic vacuum adsorption substrate, 102: adhesive liquid, 103: coating scraper). Detailed Implementation

[0021] To make the objectives and technical solutions of this invention clearer, the following embodiments are provided for further explanation. However, the scope of protection of this invention is not limited to these embodiments; the embodiments are merely for illustrative purposes. Those skilled in the art should understand that any changes or equivalent substitutions that do not depart from the concept of this invention are included within the scope of protection of this invention.

[0022] Unless otherwise specified, all reagents and raw materials used in this invention are obtained through purchase.

[0023] Example 1 Step 1, Preparation of the screen template: Taking an 8-inch wafer as an example (diameter 200mm, thickness 725μm), according to the 200mm wafer size, the required opening pattern (specifically a circle with a diameter of 199mm) is made on the screen using photosensitive plate-making technology. The hollow pattern (specifically a circular concentric double-ring composite pattern with square mesh) matching the coating area of ​​the wafer is made on the screen using photolithography or laser etching. A stainless steel screen with a fine coating area (functional area) of 450 mesh and a thick coating area (edge ​​blank area) of 240 mesh is obtained. The screen thickness is 30μm and the screen opening ratio is 54%. The accuracy of the hollow edge area of ​​the pattern is controlled within ±0.01mm and fixed on a metal frame to obtain a screen template with a tension of 25N / cm.

[0024] Step 2, Applying Adhesive: After maintaining the adhesive solution at 10℃ for 1 hour, adjust the viscosity of the back-grinding protective adhesive solution (CST-2000-0003, Kairuien, viscosity of 2990~3015mPa·s) to 3000mPa·s. Use a vacuum degassing machine to degas for 45 minutes at -0.1MPa pressure to obtain the degassed adhesive solution. Lay the 8-inch wafer flat on a microporous ceramic vacuum adsorption substrate (levelness error ≤0.005mm / m), then turn on the vacuum to firmly adsorb the wafer onto the substrate. Then, lay the screen template obtained in Step 1 flat on top of the wafer, with a spacing of 0.15mm between the screen template and the wafer surface. The degassed adhesive (CST-2000-0003) was applied in a linear fashion to the starting position of the squeegee on the screen. The length of the adhesive strip (195mm) was slightly smaller than the width of the coating area (199mm), and the thickness was sufficient to cover the mesh without overflow. Using a polyurethane squeegee, 10g of adhesive was pushed onto the screen at a speed of 12mm / s, with a 60° angle between the squeegee and the screen. The squeegee hardness was 90 Shore A. The adhesive was transferred through the screen mesh to the wafer surface. The squeegee pressure was controlled at 0.008MPa to ensure uniform adhesive transfer. After coating, the screen template was peeled vertically upwards at a speed of 5mm / s and dried at 28℃ for 5 minutes. This process was repeated three times to obtain a coated wafer with an adhesive layer thickness of 80μm. Figure 3 As shown.

[0025] Step 3, Pre-curing: Place the coated wafer obtained in Step 2 into a heating oven for pre-curing treatment to obtain a pre-cured wafer. Use hot air circulation heating to place the coated wafer in a 95°C heating oven for 7 minutes to evaporate some of the solvent in the adhesive, so that the adhesive layer is initially cured and shaped, avoiding the flow and deformation of the adhesive during subsequent hot pressing. The humidity of the cavity during the pre-curing process is 40% to prevent water vapor condensation on the surface of the adhesive layer.

[0026] Step 4, Hot pressing: Place the pre-cured wafer obtained in step 3 into a hot press ( Figure 2The wafer is hot-pressed at 160°C for 60 seconds on the lower mold heating plate and the mold in mold 303 (the hot press servo cylinder 301 pushes the hot press movable plate 302 and the lower mold heating plate and mold 303 to move upward, and stops moving when the pressure reaches 1MPa and enters the pressure holding state). The wafer after hot pressing is obtained. The thickness difference of the wafer after hot pressing is ≤8μm, which is reduced by nearly 50%.

[0027] Example 2 Step 1, Preparation of the screen template: Taking a 12-inch wafer as an example (300mm in diameter, 775μm in thickness), according to the 300mm wafer size, the required opening pattern (specifically a circle with a diameter of 299mm) is made on the screen using photosensitive lithography. The hollow pattern (specifically a circular concentric double-ring composite pattern with square mesh) matching the coating area of ​​the wafer is made on the screen using photolithography or laser etching. The resulting stainless steel screen has a fine coating area with a mesh count of 350 mesh and a thick coating area with a mesh count of 200 mesh. The screen thickness is 45μm and the screen opening rate is 65%. The accuracy of the hollow edge area of ​​the pattern is controlled within ±0.01mm. The screen is then fixed on a metal frame to obtain a screen template with a tension of 28N / cm.

[0028] Step 2, Adhesive Coating: After maintaining the adhesive solution at 10℃ for 1 hour, adjust the viscosity of the back-grinding protective adhesive solution (CST-2000-0015, Kairuien, viscosity 14960~15050mPa·s) to 15000mPa·s. Use a vacuum degassing machine to degas for 60 minutes at -0.3MPa pressure to obtain the degassed adhesive solution. Lay a 12-inch wafer flat on a microporous ceramic vacuum adsorption substrate (levelness error ≤0.005mm / m), then turn on the vacuum to firmly adsorb the wafer onto the substrate. Then lay the screen template obtained in Step 1 flat on top of the wafer, with a spacing of 0.25mm between the screen template and the wafer surface. The degassed adhesive (CST-2000-0015) was applied in a linear fashion to the starting position of the squeegee on the screen. The length of the adhesive strip (295mm) was slightly smaller than the width of the coating area (299mm), and the thickness was such that it covered the mesh without overflowing. Using a polyurethane squeegee, 15g of adhesive was pushed onto the screen at a speed of 6mm / s, with the squeegee and screen at an angle of 40° and a squeegee hardness of 90 Shore A. The adhesive was transferred to the wafer surface through the mesh. The squeegee pressure was controlled at 0.008MPa to ensure uniform adhesive transfer. After coating, the screen template was peeled vertically upwards at a speed of 8mm / s and dried at 25℃ for 3 minutes. This process was repeated 3 times to obtain the coated wafer. The adhesive layer thickness of the coated wafer was 110μm.

[0029] Step 3, Pre-curing: Place the coated wafer obtained in Step 2 into a heating oven for pre-curing treatment to obtain a pre-cured wafer. Use hot air circulation heating to place the coated wafer in an 83°C heating oven for 5 minutes to evaporate some of the solvent in the adhesive, so that the adhesive layer is initially cured and shaped, avoiding the flow and deformation of the adhesive during subsequent hot pressing. The humidity of the cavity during the pre-curing process is 35% to prevent water vapor condensation on the surface of the adhesive layer.

[0030] Step 4, Hot pressing: Place the pre-cured wafer obtained in step 3 into a hot press ( Figure 2 The wafer is hot-pressed at 160°C for 60 seconds on the lower mold heating plate and mold 303 (the hot press servo cylinder 301 pushes the hot press movable plate 302 and the lower mold heating plate and mold 303 to move upward, and stops moving when the pressure reaches 1.2MPa to enter the pressure holding state), and the wafer after hot pressing is obtained. The thickness difference of the wafer after hot pressing is ≤9μm.

[0031] Example 3 Step 1, Preparation of the screen template: Taking a PLP substrate as an example (size 300mm×300mm, thickness 500μm), according to the substrate size, the required opening pattern (specifically square, side length 299mm) is made on the screen using photosensitive plate-making technology. The hollow pattern (specifically square concentric double ring composite pattern, square mesh) matching the adhesive coating area of ​​the PLP substrate is made on the screen using photolithography or laser etching. The resulting stainless steel screen has a fine adhesive coating area of ​​450 mesh and a thick adhesive area of ​​240 mesh, a screen thickness of 30μm, and a screen opening rate of 54%. The accuracy of the hollow edge area of ​​the pattern is controlled within ±0.01mm, and it is fixed on a metal frame to obtain a screen template with a tension of 25N / cm.

[0032] Step 2, Adhesive Coating: After maintaining the adhesive solution at 10℃ for 1 hour, adjust the viscosity of the back-grinding protective adhesive solution (CST-2000-0003, Kairuien, viscosity 2990~3015mPa·s) to 3000mPa·s. Use a vacuum degassing machine to degas for 45 minutes at -0.1MPa pressure to obtain the degassed adhesive solution. Lay the PLP substrate flat on a microporous ceramic vacuum adsorption platform (levelness error ≤0.005mm / m), then turn on the vacuum to firmly adsorb the PLP substrate onto the platform. Then, lay the screen template obtained in Step 1 flat on top of the PLP substrate, with a spacing of 0.15mm between the screen template and the wafer surface. The degassed adhesive (CST-2000-0003) was applied in a linear fashion to the starting position of the squeegee on the screen. The length of the adhesive strip (295mm) was slightly smaller than the width of the coating area (299mm), and the thickness was such that it covered the mesh without overflowing. Using a polyurethane squeegee, 12g of adhesive was pushed onto the screen at a speed of 12mm / s, with the angle between the squeegee and the screen at 60° and the squeegee hardness at 90 Shore A. The adhesive was transferred to the wafer surface through the mesh. The squeegee pressure was controlled at 0.008MPa to ensure uniform adhesive transfer. After coating, the screen template was peeled off vertically upwards at a speed of 5mm / s and dried at 28℃ for 5min. This process was repeated 3 times to obtain the coated PLP substrate. The adhesive layer thickness of the coated PLP substrate was 80μm.

[0033] Step 3, Pre-curing: Place the PLP substrate obtained in Step 2 after coating in a heating oven for pre-curing treatment to obtain a pre-cured PLP substrate. Use hot air circulation heating to place the coated PLP substrate in a heating oven at 95°C for 7 minutes to evaporate some of the solvent in the adhesive, so that the adhesive layer is initially cured and shaped, avoiding the flow and deformation of the adhesive during subsequent hot pressing. The humidity of the cavity during the pre-curing process is 40% to prevent water vapor condensation on the surface of the adhesive layer.

[0034] Step 4, Hot Pressing: Place the pre-cured PLP substrate obtained in Step 3 into a hot press ( Figure 2 The PLP substrate is hot-pressed at 160°C for 60 seconds on the lower mold heating plate and mold 303 (the hot press servo cylinder 301 pushes the hot press movable plate 302 and the lower mold heating plate and mold 303 to move upward, and stops moving when the pressure reaches 1.3MPa and enters the pressure holding state), and the thickness difference of the PLP substrate after hot pressing is ≤8μm.

[0035] Comparative Example 1 The difference from Example 1 is that no screen printing plate is needed. The degassed adhesive is directly dropped onto the center of the wafer and diffused outward by extrusion. The wafer thickness difference can only reach 15μm.

[0036] Comparative Example 2 Step 1, Adhesive Coating: After maintaining the adhesive solution at 10℃ for 1 hour, adjust the viscosity of the back-abrasion protective adhesive solution (CST-2000-0003, Kairuien, viscosity 2990~3015 mPa·s) to 3000 mPa·s. Degas the adhesive solution using a vacuum degassing machine at -0.1 MPa pressure for 45 minutes to obtain the degassed adhesive solution. Place the 8-inch wafer on the spin coater, turn on the vacuum to firmly adhere the wafer to the calibrated spin coater. Keep the spin coater stationary and drop 30g of the degassed adhesive solution (CST-2000-0003) onto the center of the wafer. First, adjust the spin coater speed to 800 rpm for 10 seconds, then adjust the speed to 5000 rpm for 50 seconds, and finally decelerate to stop at 500 rpm / s. After spin coating, place the wafer in an oven and bake at 80°C for 15 minutes. Repeat this process 3 times to obtain the coated wafer. The coating thickness of the coated wafer is 80 μm.

[0037] Step 2, Curing: Place the softened wafer obtained in Step 1 in an oven and treat it at 90℃ for 30 minutes, then at 180℃ for 60 minutes to obtain a wafer with a surface coating. The thickness difference of the wafer is ≤20μm.

[0038] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A process method based on uniform adhesive coating and hot pressing of a screen, characterized in that, Includes the following steps: Step 1, Preparation of the screen template: Create opening patterns and cutout patterns on the screen that match the coating area of ​​the wafer or PLP substrate, and fix it on the metal frame to obtain the screen template. Step 2, coating: Fix the wafer or PLP substrate on the vacuum adsorption stage, and cover the surface of the wafer or PLP substrate with the screen template prepared in step 1 in parallel. The length of the adhesive strip is less than the width of the coating area. Use a polyurethane scraper or a metal scraper to scrape the adhesive along the surface of the screen. Peel the screen template vertically upward, dry, and repeat the scraping-peeling operation to obtain the coated wafer or PLP substrate. Step 3, Pre-curing: Place the coated wafer or PLP substrate obtained in Step 2 into a heating furnace for pre-curing treatment to obtain a pre-cured wafer or PLP substrate. Step 4, hot pressing: Place the pre-cured wafer or PLP substrate obtained in step 3 on a hot press and hot press it to obtain the hot-pressed wafer or PLP substrate.

2. The process method according to claim 1, characterized in that, The wafer size mentioned in step 1 is one of 6 inches, 8 inches, or 12 inches; The size of the PLP substrate mentioned in step 1 is one of 300mm×300mm, 510mm×515mm, and 600mm×600mm; The opening pattern in step 1 is either a circle with a diameter 0.5-2 mm smaller than the wafer diameter or a square with a side length 0.5-2 mm smaller than the PLP substrate. The hollowed-out pattern mentioned in step 1 is a circular concentric double-ring composite pattern, a square concentric double-ring composite pattern, etc., and the mesh is square; The wire mesh mentioned in step 1 is a woven wire mesh made of stainless steel wire or polyester wire, with a mesh count of 100~500 mesh, of which the fine adhesive coating area is 300~500 mesh, the thick adhesive area is 200~250 mesh, the thickness is 15~100 μm, and the opening ratio is 45%~75%.

3. The process method according to claim 1, characterized in that, The edge area of ​​the hollowed-out pattern described in step 1 is controlled with an accuracy of ±0.01mm; The tension of the wire mesh template mentioned in step 1 is 25~30 N / cm.

4. The process method according to claim 1, characterized in that, The levelness error of the vacuum adsorption worktable in step 2 is ≤0.005mm / m; In step 2, the distance between the screen template and the surface of the wafer or PLP substrate is 0.1~0.3mm; The viscosity of the adhesive solution in step 2 is 500~20000 mPa·s.

5. The process method according to claim 1, characterized in that, The coating-peeling operation described in step 2 is as follows: Apply the adhesive in a linear fashion to the starting position of the squeegee on the screen. The length of the adhesive strip is less than the width of the coating area. Use a polyurethane squeegee or a metal squeegee to uniformly coat the adhesive along the screen surface at a speed of 5-15 mm / s. The angle between the squeegee and the screen is 35-90°. The coating pressure is 0.005-0.02 MPa. After coating, peel the screen template vertically upward at a speed of 5-10 mm / s. Dry at 20-30°C for 3-5 minutes. Repeat the operation 2-3 times to obtain the coated wafer or PLP substrate. The length of the adhesive strip is 3-5 mm smaller than the size of the wafer or PLP substrate, and the width of the adhesive coating area is 0.5-2 mm smaller than the size of the wafer or PLP substrate. The wire mesh has a line width of 20~60μm; The adhesive layer thickness of the coated wafer or PLP substrate is 50~200μm.

6. The process method according to claim 1, characterized in that, The pre-curing process in step 3 is as follows: hot air circulation heating is used to place the coated wafer or PLP substrate in a heating oven at 80~100℃ for 5~8 minutes. During the pre-curing process, the humidity of the cavity is 30~50%.

7. The process method according to claim 1, characterized in that, In step 4, the hot pressing process specifically involves placing the pre-cured wafer or PLP substrate onto the hot pressing mold of the hot press machine and raising the temperature to 120-160°C at a rate of 5-10°C / min. The mold is then pressed down at a pressure of 0.5-2MPa at a uniform speed for 1-2 minutes. During the hot pressing process, a vacuum is simultaneously drawn to make the cavity vacuum degree -100Pa to -50Pa.

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