A printing worktable mechanism to improve screen printing plate lifespan

Abstract

This invention relates to a printing worktable mechanism for improving the lifespan of printing screens. It includes a base plate, with front support plates mounted on the front and rear sides, and side support plates mounted on the left and right sides. Adsorption plates are mounted on the front and side support plates. A connecting plate is mounted on the front support plate, and a first negative pressure switch and a second negative pressure switch are mounted on the connecting plate. A pad is mounted on the adsorption plate, and a pressure plate is mounted on the pad. A rectangular opening is formed between the pad and the pressure plate, and a product adsorption plate is placed at the rectangular opening on the adsorption plate. An AMB substrate is placed on the upper surface of the product adsorption plate. The pressure plate is made of 3mm thick stainless steel. This invention has a simple structure and reasonable design, aiming to solve the problem of short screen lifespan in existing AMB substrate printing processes, thereby improving screen lifespan and reducing product costs.

Description

Technical Field

[0001] This invention relates to the field of screen printing machines, and more particularly to a printing worktable mechanism for improving the service life of screen printing plates. Background Technology

[0002] The increasing power and high integration of power electronic devices generate significant heat during operation. If this heat cannot be dissipated effectively and promptly, the performance of the power electronic devices will be affected, and they may even be damaged. This necessitates that the ceramic substrates responsible for insulation and heat dissipation possess excellent mechanical and thermal properties. Due to the high thermal conductivity, shock resistance, and good mechanical properties of Si3N4 ceramics at high temperatures, and depending on the different processes used to achieve copper plating followed by etching, commonly used ceramic heat dissipation substrates are categorized into HTCC, LTCC, DBC, and AMB, with AMB being the most prevalent process for Si3N4 ceramic substrates. AMB ceramic substrates possess excellent thermal conductivity and bending strength, making the new energy vehicle sector the largest demand area for AMB substrates.

[0003] The AMB process involves directly mixing Ag, Cu, and Ti elements in powder form to form a slurry. The Ag-Cu-Ti solder is then printed onto a silicon nitride ceramic substrate using screen printing technology. Copper foil is then laminated onto the solder using hot pressing technology. Finally, the AMB Si3N4 ceramic substrate that meets the requirements is prepared through sintering, photolithography, etching, and Ni plating processes.

[0004] Screen printing is a crucial process, completed by a printing machine. The printing process is described as follows: The operator places the AMB substrate onto the worktable at the operating position. It is then fixed using air suction. After visual alignment, the worktable moves to directly beneath the screen, and the squeegee applies pressure to the screen to complete the printing. After printing, the worktable returns to the operating position.

[0005] The printing press applies pressure to the screen using a squeegee, printing the image onto the AMB substrate. The screen is fixed to a frame, and the two together form the screen printing plate. During the printing process, the screen must be maintained within a certain tension range. Excessive tension causes the screen to lose its resilience, while insufficient tension makes the screen soft and prone to deformation, affecting printing accuracy and quality. In mass production applications of the printing process, a tension meter must be used to measure the tension at five points on the screen before printing: one point at each of the four quadrants' far corners and one point at the center. If the tension exceeds a set value, it indicates that the screen has reached the end of its service life and must be replaced.

[0006] Screen printing is a fundamental element of screen printing, and its production process is complex and requires high precision. First, a photosensitive emulsion with good plate-making performance and easy coating is selected. This emulsion is then evenly applied to the screen in a darkroom, followed by drying. The screen is then exposed, developed, and dried on a screen exposure machine to complete the screen printing process. Screens constitute a significant portion of the product's cost; therefore, effectively extending screen lifespan is a primary way to reduce costs.

[0007] Currently, printing worktables use either ceramic suction cups or metal through-hole worktables. The AMB substrate is placed on the surface of the worktable and secured by air suction. This method has the following drawbacks:

[0008] Firstly, the lower surface of the AMB substrate is adsorbed onto the upper surface of the worktable. There is a thickness difference between the upper surface of the AMB substrate and the upper surface of the worktable. Under the pressure of the squeegee, the screen generates elastic grooves with a steep increase in thickness at the beginning of the substrate edge and elastic grooves with a steep decrease in thickness at the end of the substrate edge.

[0009] Printing process description: Figure 5 Point A is the initial printing point, i.e., the point where the squeegee descends; point B is the starting point at the substrate edge; point C is the ending point at the substrate edge; and point D is the final printing point, i.e., the point where the squeegee ascends. The printing action begins when the squeegee descends from point A and ends when it ascends from point D. Because the upper surface of the AMB substrate is not on the same plane as the worktable, a triangular groove appears in the screen at point B. The greater the thickness of the AMB substrate, the larger the area of ​​the triangular groove. The squeegee also passes through the screen at point C, where a triangular groove appears again. Throughout the printing process, two rectangular grooves formed by these triangular shapes are created.

[0010] The grooves cause abrupt changes in stress at the beginning and end of the substrate edge, leading to abrupt deformation. With increasing printing cycles, the deformation at both points changes from elastic to plastic, significantly reducing the screen tension and rendering it unusable, necessitating replacement. This problem is more severe with nylon screens, which have lower toughness. The lifespan of screens used for printing on AMB substrates is significantly shorter than that used for LTCC and HTCC substrates.

[0011] Secondly, the AMB substrate has grooves of a certain depth on its lower surface. When using a ceramic suction cup or a metal through-hole stage to hold the AMB substrate, local air leakage will occur at the grooves. Due to the different types of AMB substrates, the location of the grooves on the lower surface of the substrate is different, resulting in different locations of local air leakage. This makes it impossible to firmly fix the ceramic substrate on the stage, causing it to move under the action of the squeegee, which greatly reduces the printing position accuracy of the pattern. The current method is to manually stick the substrate to the stage with tape around its perimeter, and then remove the tape after printing. This results in a high degree of manual intervention and low production efficiency.

[0012] Thirdly, the AMB substrate is a rigid substrate with a thickness of 0.25mm to 1.5mm, a difference of 1.25mm, which is quite significant. As the substrate thickness increases, the greater the thickness, the greater the depth and area of ​​the grooves that the stencil creates at the beginning and end of the substrate edge. The shorter the time it takes for the grooves to transition from elasticity to plasticity, the shorter the lifespan of the stencil.

[0013] Based on the three drawbacks of the above working conditions, it is necessary to design a worktable mechanism that can be applied to AMB substrates of different thicknesses to solve three problems: first, to solve the problem of reduced screen lifespan; second, to solve the problem that the screen lifespan decreases significantly with the increase of AMB substrate thickness; and third, to solve the problem that the grooves on the lower surface of the AMB substrate cannot be firmly adsorbed onto the worktable. Summary of the Invention

[0014] Therefore, the purpose of this invention is to provide a printing worktable mechanism that improves the service life of the screen printing plate, firstly solving the problem of reduced screen printing plate service life, and secondly solving the problem that the service life of the screen printing plate decreases as the thickness of the AMB substrate increases.

[0015] To achieve the above objectives, the following technical solution is adopted:

[0016] A printing worktable mechanism for improving the service life of screen printing plates includes a base plate, a front support plate installed on the front and rear sides of the base plate, a side support plate installed on the left and right sides of the base plate, and an adsorption table plate installed on the front support plate and the side support plate.

[0017] A connecting plate is installed on the front support plate, and a first negative pressure switch and a second negative pressure switch are installed on the connecting plate;

[0018] A pad is installed on the adsorption platform, and a pressure plate is provided on the pad. A rectangular opening is opened in the middle of the pad and the pressure plate, and a product adsorption plate is placed on the adsorption platform at the rectangular opening of the pad and the pressure plate.

[0019] An AMB substrate is placed on the upper surface of the product's adsorption plate.

[0020] Preferably, the pressure plate is made of stainless steel with a thickness of 3mm.

[0021] Preferably, the pad is made of stainless steel sheets with different thicknesses of 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.8mm, and 1.0mm.

[0022] Preferably, the product adsorption plate is made of stainless steel sheets with different thicknesses of 0.2mm, 0.3mm, 0.4mm, 0.5mm and 0.8mm, with the thickness direction being a non-machined plane, thus ensuring the parallelism of the upper and lower surfaces of the product adsorption plate.

[0023] Preferably, the upper part of the adsorption platform is a boss, and the length and width of the boss are the same as the length and width of the AMB substrate and the product adsorption plate; the rectangular opening between the pressure plate and the pad has the same length and width.

[0024] The rectangular opening between the pressure plate and the pad is larger than the length and width of the boss on the adsorption platform, which facilitates the smooth loading and unloading of the AMB substrate from the worktable.

[0025] Preferably, the upper surface of the adsorption platform is provided with two negative pressure adsorption holes, which include an inner ring adsorption hole and an outer ring adsorption hole. The inner ring adsorption hole is formed by two concentric holes of different diameters, with the upper section having a diameter of 3 mm and the lower section having a diameter of 0.8 mm.

[0026] The outer ring of adsorption holes has a diameter of 1mm and is used to adsorb products onto the adsorption plate.

[0027] Preferably, the pressure plate, pad plate and adsorption platform have rectangular slots in the front and back directions, which facilitates manual handling of ceramic substrates in semi-automatic printing mode and pneumatic grippers in fully automatic printing mode.

[0028] The beneficial effects of this invention are:

[0029] This invention has a simple structure and reasonable design. It aims to solve the problem of short screen life in the existing AMB substrate printing process, thereby increasing the screen life and reducing product costs. Attached Figure Description

[0030] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0031] Figure 1 This is a schematic diagram of the structure of the present invention;

[0032] Figure 2 This is a schematic diagram of the adsorption platform in this invention;

[0033] Figure 3 This is a schematic diagram of the structure of the pad in this invention;

[0034] Figure 4 This is a schematic diagram of the structure of the product adsorption plate in this invention;

[0035] Figure 5 This is a schematic diagram of the printing process in the prior art of the present invention.

[0036] Figure 6 This is a schematic diagram of the printing process of the present invention;

[0037] Figure 7 for Figure 6 A magnified structural diagram of A in the middle;

[0038] Figure 8 This is a top view of the structure of the present invention during printing. Detailed Implementation

[0039] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0040] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0041] Please refer to Figure 1-4 As shown, a printing worktable mechanism for improving the service life of screen printing includes a base plate 1, a front support plate 2 installed on the front and rear sides of the base plate 1, a side support plate 3 installed on the left and right sides of the base plate 1, and an adsorption table plate 4 installed on the front support plate 2 and the side support plate 3.

[0042] A connecting plate 5 is installed on the front support plate 2, and a first negative pressure switch 6 and a second negative pressure switch 7 are installed on the connecting plate 5.

[0043] A pad 8 is installed on the adsorption platform 4, and a pressure plate 9 is provided on the pad 8. A rectangular opening is provided in the middle part of the pad 8 and the pressure plate 9. A product adsorption plate 10 is placed on the adsorption platform 4 at the rectangular opening of the pad 8 and the pressure plate 9. An AMB substrate 14 is placed on the upper surface of the product adsorption plate 10.

[0044] The front support plate 2 and the side support plate 3 are connected to the base plate 1 with hexagon socket head cap screws; the connecting plate 5 is connected to the front support plate 2 with hexagon socket head cap screws, and the pressure plate 9 and the pad plate 8 are fixed to the adsorption platform 4 with hexagon socket countersunk screws. The product adsorption plate 10 is placed on the adsorption plane of the adsorption platform 4, and the air adsorption of the second negative pressure switch 7 is turned on, so that the product adsorption plate 10 is fixed to the adsorption platform 4 by negative pressure adsorption; the AMB substrate 14 is placed on the upper surface of the product adsorption plate 10, and the air adsorption of the first negative pressure switch 6 is turned on, so that the AMB substrate 14 is fixed to the product adsorption plate 10 by negative pressure adsorption.

[0045] The pressure plate 9, pad plate 8 and adsorption platform 4 have rectangular slots 11 in the front and back directions. In the semi-automatic printing mode, it is convenient for the human hand to pick up and put down the ceramic substrate. In the fully automatic printing mode, it is convenient for the pneumatic gripper to pick up and put down the ceramic substrate.

[0046] The pressure plate 9 is made of 3mm thick stainless steel to ensure that the upper surface is worn by the squeegee during printing, preventing the printing paste from corroding the upper surface. The pad 8 is made of stainless steel sheets of different thicknesses, such as 0.3mm, 0.5mm, 0.8mm, and 1mm, with the thickness direction being a non-processed plane. Due to the limited thickness options of the pad 8, the thickness is a non-continuous value. Adjusting the upper surface of the ceramic substrate and the pressure plate 9 to be on the same plane limits the types of ceramic substrate thickness that can be printed. Therefore, this method is suitable for printing applications where the minimum thickness difference of the product is greater than 0.1mm. Product adsorption plate 10 is made of stainless steel sheets with different thicknesses of 0.2mm, 0.3mm and 0.5mm, with the thickness direction being a non-processed plane; the adsorption platform 4 has two negative pressure paths, with small holes in the outer ring adsorbing the product adsorption plate 10 and small holes in the inner ring adsorbing the AMB substrate 141; since the lower surface of the ceramic substrate has shallow grooves, the position of the small holes in the product adsorption plate 10 is different depending on the groove position of different products. Therefore, different product adsorption plates 10 are used for different ceramic substrates, so as to ensure that the ceramic substrate can still be fixed on the adsorption platform 4 under the action of the squeegee pressure during printing, thereby ensuring the positional accuracy of the printed pattern.

[0047] Reference Appendix Figure 6 , 7 In point 8, point A is the initial printing point, which is the point where the squeegee 13 descends; point B is the starting point of the substrate edge; point C is the ending point of the substrate edge; and point D is the ending printing point, which is the point where the squeegee 13 ascends. The printing action begins when the squeegee 13 descends from point A and ends when it ascends from point D. Figure 8 The image shows the state of the wire mesh 12 after the scraper 13 passes through point B. No grooves appear on the wire mesh 12 at point B. (Enlarged view shown). Figure 7 As shown. No grooves were formed throughout the entire printing process.

[0048] The upper part of the adsorption platform 4 has a boss, the length and width of which are consistent with the length and width of the AMB substrate 14 and the product adsorption plate 10. The rectangular opening between the pressure plate 9 and the pad 8 has the same length and width. The rectangular opening between the pressure plate 9 and the pad 8 has a larger length and width than the boss of the adsorption platform 4, which facilitates the smooth removal and placement of the AMB substrate 14 from the worktable. Two negative pressure adsorption holes are opened on the upper surface of the adsorption platform 4. The negative pressure adsorption holes include an inner ring adsorption hole and an outer ring adsorption hole. The inner ring adsorption hole is formed by two concentric holes with different diameters. The upper diameter is 3mm and the lower diameter is 0.8mm. The first negative pressure switch 6 and the second negative pressure switch 7 are used to control the two negative pressure adsorption holes of the adsorption platform 4. The outer ring adsorption hole has a diameter of 1mm and is used to adsorb the product adsorption plate 10. The product adsorption plate 10 ensures that the AMB substrate 14 is supported on the whole surface, which ensures stable support under the action of the squeegee during printing.

[0049] The length of the squeegee 13 is greater than the length of the AMB substrate 14 in the printing direction, ensuring that the squeegee 13 does not enter the gaps around the pressure plate 9 and the AMB substrate 14 at the beginning and end of the edge of the AMB substrate 14 during the printing process.

[0050] The pressure plate 9, pad plate 8 and adsorption platform 4 have rectangular slots 11 in the front and back directions, which facilitate manual handling of ceramic substrates in semi-automatic printing mode and pneumatic grippers in fully automatic printing mode.

[0051] The lower surface of the AMB substrate 14 has two states: either it has grooves or it does not.

[0052] If there is no groove of a certain depth, the position of the small hole of the product adsorption plate 10 corresponds completely with the adsorption hole of the inner ring of the adsorption platform 4. The diameter of the small hole of the product adsorption plate 10 is 1mm, which is 0.8mm larger than the diameter of the lower section of the inner ring of the adsorption platform 4. This avoids the situation where the two holes are not completely concentric, so that the air cannot completely pass through the adsorption platform 4 and thus affect the air flow and thus affect the adsorption force of the AMB substrate 14.

[0053] If a groove of a certain depth exists, the position of the small holes on the product's adsorption plate 10 must avoid the groove opening; that is, there are no adsorption small holes at the position corresponding to the groove opening, thus forming... Figure 4 The small hole layout is shown. Figure 4Four product adsorption plates 10 are listed for substrates with four different groove positions. The position of the small hole in the product adsorption plate 10 is different according to the groove position of different products. Therefore, different AMB substrates 14 use different product adsorption plates 10 to ensure that the substrate can still be fixed on the adsorption table 4 under the action of squeegee pressure during printing, thereby ensuring the positional accuracy of the printed pattern. The product adsorption plates 10 are made of stainless steel sheets with different thicknesses of 0.2mm, 0.3mm, 0.4mm, 0.5mm and 0.8mm, which are laser-cut. The thickness direction is a non-processed plane to ensure the parallelism of the upper and lower surfaces of the product adsorption plates 10.

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. 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 printing worktable mechanism for improving the service life of screen printing plates, comprising a base plate, characterized in that, Support front plates are installed on the front and rear sides of the base plate, support side plates are installed on the left and right sides of the base plate, and adsorption platforms are installed on the support front plates and support side plates. A connecting plate is installed on the front support plate, and a first negative pressure switch and a second negative pressure switch are installed on the connecting plate; A pad is installed on the adsorption platform, and a pressure plate is provided on the pad. A rectangular opening is opened in the middle of the pad and the pressure plate, and a product adsorption plate is placed on the adsorption platform at the rectangular opening of the pad and the pressure plate. An AMB substrate is placed on the upper surface of the product's adsorption plate; The upper part of the adsorption platform is a boss, the length and width of which are consistent with the length and width of the AMB substrate and the product adsorption plate; the rectangular opening between the pressure plate and the pad has the same length and width. The rectangular opening between the pressure plate and the pad is larger than the length and width of the boss on the adsorption platform, which makes it easier to pick up and put the AMB substrate from the worktable. The upper surface of the adsorption platform has two negative pressure adsorption holes, including an inner ring adsorption hole and an outer ring adsorption hole. The inner ring adsorption hole is formed by two concentric holes of different diameters, with the upper section having a diameter of 3mm and the lower section having a diameter of 0.8mm. The outer ring of adsorption holes has a diameter of 1mm and is used to adsorb products onto the adsorption plate.

2. The printing worktable mechanism for improving the service life of a screen printing plate according to claim 1, characterized in that, The pressure plate is made of 3mm thick stainless steel.

3. The printing worktable mechanism for improving the service life of a screen printing plate according to claim 2, characterized in that, The pad is made of stainless steel sheets with different thicknesses of 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.8mm and 1.0mm.

4. A printing worktable mechanism for improving the service life of a screen printing plate according to claim 3, characterized in that, The product adsorption plate is made of stainless steel sheets with different thicknesses of 0.2mm, 0.3mm, 0.4mm, 0.5mm and 0.8mm. The thickness direction is a non-machined plane, which ensures the parallelism of the upper and lower surfaces of the product adsorption plate.

5. A printing worktable mechanism for improving the service life of a screen printing plate according to claim 4, characterized in that, The pressure plate, pad, and adsorption platform are provided with rectangular slots in the front and back directions. In the semi-automatic printing mode, this facilitates manual handling of the AMB substrate, and in the fully automatic printing mode, it facilitates pneumatic gripper handling of the AMB substrate.

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