A thick film vacuum printing apparatus

Abstract

This utility model belongs to the field of printing technology, and particularly relates to a thick film vacuum printing device, including a vacuum pump, a vacuum tank, and a printing machine. The printing machine has a working chamber formed by the cooperation of a substrate and a printing table, which can be quickly evacuated by the vacuum tank. The gas-filled sealing ring of the substrate cooperates with the limiting ring plate of the printing table to achieve double sealing. The screen assembly includes a screen frame, a screen body, and a lifting mechanism, facilitating quick screen replacement. Compared with the prior art, this utility model mainly solves the problems of air bubble ingress, paste evaporation, and printing defects in existing thick film printing. The equipment enables rapid vacuum, low energy consumption, and high-efficiency printing, effectively improving the production efficiency and product yield of thick film printing, and is suitable for the mass production of high-precision thick film electronic components.

Description

Technical Field

[0001] This utility model relates to the field of printing technology, and more specifically, to a thick film vacuum printing device. Background Technology

[0002] Printing processes are involved in the manufacturing of electronic components, such as printing circuit wires and pads; printing resistors, capacitors, inductors, and protective dielectrics; and printing vias and buried holes. The printing pastes can be metallic or non-metallic. After printing, the components are dried and sintered to form electronic components with different functions. This type of printing is also known as thick film printing.

[0003] Currently, traditional thick film printing processes are all conducted in an atmospheric environment. Existing processes can generally meet the requirements for products with relatively thin film layers. They can reduce air bubbles and avoid printing defects by adding defoamers to the paste, although defoamers will weaken the bonding strength between the printed film layer and the substrate.

[0004] For products with very thick printed film layers, such as those with a wet film thickness >50µm, air bubbles in the slurry have a significant impact. For example, thick-film stainless steel heating plates require a dry film thickness >100µm and a wet film thickness >200µm to withstand high pressure. If air bubbles are present, the pressure test will fail, resulting in scrap. Therefore, currently, thick-film stainless steel heating plates are printed and sintered four times to reduce the film thickness with each printing, thus avoiding air bubble formation and improving yield. However, this method is inefficient, energy-wasting, and the continuous high-temperature sintering causes substrate warping and deformation.

[0005] Printing fine lines is also a challenge. For example, when printing lines <50µm, if the ink contains air bubbles that are >50µm, it may cause problems with the connection of the lines.

[0006] The surface roughness of the printed circuit board is also a problem. A rough surface morphology increases the specific surface area, which is beneficial to improving the adhesion. However, there is also a problem: will the air adsorbed on the rough surface and covered by the paste also weaken the adhesion? Would it be better if there was no air adsorption?

[0007] With the increasing density of electronic products, many via filling processes are involved. Via filling is the process of electrically connecting the front and back sides of an electronic substrate. This is done by drilling holes in the substrate and then filling the holes with metal paste to achieve electrical connection. Some products use substrates with non-through holes, where the connection is made to the internal circuit layers. Current via filling processes typically involve placing the substrate on a micro-via ceramic printing plate, creating a vacuum, and then using a printing squeegee to press the paste into the substrate's holes. This process inevitably leaves air bubbles in the paste, which can form voids after sintering, affecting component reliability. Furthermore, it is particularly inadequate for filling blind vias.

[0008] The basic via filling process for TGV semiconductor glass typically involves sputtering and electroplating. This process is relatively mature for vias <50µm, but voids can appear in vias >50µm. Moreover, this process is not only environmentally damaging but also extremely costly. There is an urgent need to find a new manufacturing process.

[0009] The above discussion explored the impact of air and air chambers on printing. So, is vacuum degassing of the printing paste before printing beneficial? The answer is yes. However, another issue arises: during the printing process, the printing paste is constantly turbulent, which inevitably traps many air bubbles. How can this be addressed?

[0010] Could we eliminate the influence of air on printing in a vacuum environment? That would be a good idea. Vacuum via plugging machines for PCBs are an example; they fill in through-holes and blind vias to increase circuit reliability. However, these machines are very large, weighing 6 tons and consuming 30kW of power. Changing the screen takes over 30 minutes, making them unsuitable for thick-film printing. Furthermore, establishing a vacuum takes a long time, resulting in low efficiency. Thick-film printing pastes contain many low-boiling-point volatiles, and a prolonged vacuum environment causes rapid evaporation and changes in properties. Therefore, this type of equipment is also not feasible.

[0011] In summary, an ideal printing press 3 is one that can achieve rapid vacuum printing, quick screen changing, low energy consumption, high efficiency, and operation indistinguishable from traditional thick film printing. Therefore, a thick film vacuum printing device is proposed. Utility Model Content

[0012] In view of the shortcomings of the existing technology, the purpose of this utility model is to provide a thick film vacuum printing device that solves the above-mentioned technical problems.

[0013] To achieve the above objectives, the present invention provides the following technical solution:

[0014] A thick film vacuum printing device includes a vacuum pump, a vacuum tank, and a printing machine. The printing machine has a working chamber. The vacuum tank is connected to the working chamber and the vacuum pump through a pipeline. The printing machine includes a printing plate, a printing table, and a screen assembly. The working chamber is formed by the cooperation of the printing plate and the printing table. The working chamber can be evacuated by the vacuum tank to form a vacuum chamber. The screen assembly is installed on the printing table and placed inside the working chamber.

[0015] Furthermore, the printing table includes a basin body, a mounting ring seat, and an inflatable sealing ring. The mounting ring seat is fixed to the top of the basin body and has a mounting groove for embedding the inflatable sealing ring. The printing table includes a mounting frame and a limiting ring plate. The limiting ring plate is fixed to the bottom of the mounting frame. After the inflatable sealing ring is inflated, it abuts against the limiting ring plate and is used to seal the working chamber.

[0016] Furthermore, the wire mesh assembly includes a wire mesh frame, a wire mesh body, and a lifting mechanism. The lifting mechanism is fixed in the mounting frame, and its output end is connected to the wire mesh frame. The wire mesh body is detachably connected to the wire mesh frame, and the lifting mechanism drives the wire mesh frame to extend / retract into the mounting frame.

[0017] Furthermore, the printing equipment also includes a machine body, a printing table fixed on the machine body, a printing plate slidably connected to the machine body, and the printing plate can slide to the bottom of the printing table and cooperate with the printing table.

[0018] Furthermore, a limiting groove is provided in the installation groove, and a limiting strip is provided on the side wall of the inflatable sealing ring to engage with the limiting groove. The cross-section of the limiting strip is barbed.

[0019] Furthermore, the printing table also includes a sealing cover, which is movably mounted on the top of the mounting frame and seals the top of the mounting frame. The sealing cover is made of a transparent material.

[0020] Furthermore, the lifting mechanism is either a cylinder or an electric motor.

[0021] By adopting the above technical solution, the beneficial effects of this utility model are as follows:

[0022] 1. By employing vacuum tank pre-vacuuming technology combined with the dynamic sealing structure of the printing press's working chamber, the connection between the vacuum tank and the working chamber is opened at the start of printing. This rapidly extracts air from the working chamber, quickly reducing the internal pressure and creating a vacuum environment. Compared to traditional fixed vacuum chamber equipment, the evacuation time is significantly shortened, greatly improving equipment efficiency, reducing waiting time, and significantly enhancing printing efficiency. After printing is complete, the connection between the vacuum tank and the working chamber is closed, releasing gas into the working chamber. This allows the internal pressure to quickly return to normal, enabling the printing plate to be moved out for the next cycle, further improving equipment operating efficiency and providing strong support for continuous production.

[0023] 2. Significantly Reduced Energy Consumption: By optimizing the configuration and operation of the vacuum system, and through a compact structural design, this equipment significantly reduces the footprint and energy consumption compared to traditional vacuum equipment. While ensuring printing quality, it effectively reduces energy consumption during the production process, lowers production costs, improves economic efficiency, and also contributes to energy conservation, emission reduction, and sustainable development.

[0024] 3. The equipment as a whole realizes functions such as rapid vacuuming, rapid screen changing, and high-precision printing, which can significantly improve the production efficiency of thick film printing, increase the yield of products, and is suitable for the mass production of high-precision thick film electronic components.

[0025] 4. The vacuum environment created by this equipment fundamentally reduces the opportunity for the ink to come into contact with air during the printing process, thereby effectively eliminating the problem of air bubbles caused by ink tumbling. In thick film printing, such as printing products with a wet film thickness exceeding 200 micrometers, as well as fine line printing (line width less than 50 micrometers) and hole filling processes, it can significantly reduce printing defects caused by air bubbles, such as poor line connection and voids in hole filling, thereby improving product reliability and performance stability and greatly increasing the yield of thick film printing.

[0026] 5. By adopting a dynamic sealing structure to construct a variable working chamber, the bulky structure of the traditional fixed vacuum chamber is eliminated, which greatly reduces the overall size of the equipment to the level of a conventional printing press. This not only saves factory space, but also facilitates the installation, handling and layout of the equipment, and improves the applicability and flexibility of the equipment.

[0027] 6. The inflatable sealing ring of the printing plate mates with the limiting ring plate of the printing plate to form a surface-to-surface sealing interface. After the inflatable sealing ring is inflated, its top fits tightly against the lower surface of the limiting ring plate, and after being deformed under pressure, it can evenly fill the microscopic gaps between the contact surfaces, forming a continuous sealing band. After the vacuum pump is started, the negative pressure in the working chamber further promotes the tight fit between the inflatable sealing ring and the limiting ring plate, forming a double sealing guarantee, effectively preventing the leakage of volatile substances in the printing paste, maintaining a stable vacuum in the working chamber, and ensuring the smooth progress of the printing process. Attached Figure Description

[0028] Figure 1 This is a structural schematic diagram of an embodiment of the present utility model.

[0029] Figure 2 This is a schematic diagram of the printing plate retraction structure in an embodiment of this utility model.

[0030] Figure 3 This is a schematic diagram of the structure of the wire mesh assembly being lifted according to an embodiment of the present invention.

[0031] Figure 4 This is a schematic diagram of the structure of the printing plate entering the embodiment of this utility model.

[0032] Figure 5 This is an enlarged structural diagram of part A.

[0033] Figure 6 This is a structural diagram of the wire mesh assembly, the limiting ring plate, and the mounting ring seat.

[0034] Reference numerals: 1. Vacuum pump; 2. Vacuum tank; 3. Printing machine; 31. Machine body; 32. Printing table; 321. Table body; 322. Mounting ring seat; 323. Inflatable sealing ring; 324. Limiting strip; 33. Printing table; 331. Mounting frame; 332. Limiting ring plate; 34. Screen assembly; 341. Screen frame; 342. Screen body; 343. Lifting mechanism; 35. Sealing cover; 36. Infrared sensor; 301. Working chamber; 302. Mounting groove; 303. Limiting groove. Detailed Implementation

[0035] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0036] In the description of this utility model, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0037] A thick-film vacuum printing apparatus includes a vacuum pump 1, a vacuum tank 2, and a printing machine 3. The printing machine 3 has a working chamber 301. The vacuum tank 2 is connected to the working chamber 301 and the vacuum pump 1 via a pipeline. The printing machine 3 includes a body 31, a printing plate 32, a printing table 33, a screen assembly 34, and a sealing cover 35. The working chamber 301 is formed by the cooperation of the printing plate 32 and the printing table 33, and the working chamber 301 can be evacuated by the vacuum tank 2 to form a vacuum chamber. The screen assembly 34 is installed on the printing table 33 and placed inside the working chamber 301. The printing table 33 is fixed to the body 31, and the printing plate 32 is slidably connected to the body 31. The printing plate 32 can slide to the bottom of the printing table 33 and cooperate with the printing table 33. The sealing cover 35 is movably installed on the top of the mounting frame 331 and seals the top of the mounting frame 331.

[0038] The sealing cover 35 is made of a transparent material, such as acrylic or tempered glass, allowing external light to pass through and observe the internal printing process while maintaining structural strength. When closed, the sealing cover 35 forms a physical contact surface with the top of the mounting frame 331, achieving airtight sealing through a sealing ring or precision-machined surface to ensure stable pressure inside the vacuum chamber. The transparent sealing cover 35 provides a viewing window when closed, allowing operators to directly observe the paste distribution, screen alignment, and squeegee operation within the working chamber 301 without frequently opening the chamber and disrupting the vacuum environment. When disassembling or adjusting printing components, the sealing cover 35 can be quickly opened via a hinge structure and closed after the operation. When the working chamber 301 is evacuated, the vacuum pressure ensures a tight seal between the sealing cover 35 and the sealing ring on the top of the mounting frame 331.

[0039] When the printing plate 32 moves below the printing plate 33, the inflatable sealing ring 323 is inflated, forming a sealed working chamber 301 at their contact surfaces. The vacuum tank 2 quickly extracts air from the chamber through pipelines, allowing the ink to complete the printing process in a vacuum environment. The vacuum pump 1 continuously maintains the pre-stored vacuum level in the vacuum tank 2, achieving rapid pressure regulation of the working chamber 301. After printing, gas is released into the working chamber 301 to restore normal pressure by opening the valve on the pipeline, and then the inflatable sealing ring 323 is deflated, separating the printing plate 32 from the printing plate 33. The printing plate 32 then moves out to enter the next cycle.

[0040] The printing table 32 includes a basin body 321, a mounting ring seat 322, and an inflatable sealing ring 323. The mounting ring seat 322 is fixed to the top of the basin body 321. The mounting ring seat 322 has a mounting groove 302 for embedding the inflatable sealing ring 323. The printing table 33 includes a mounting frame 331 and a limiting ring plate 332. The limiting ring plate 332 is fixed to the bottom of the mounting frame 331. After the inflatable sealing ring 323 is inflated, it abuts against the limiting ring plate 332 and seals the working chamber 301. A limiting groove 303 is formed in the mounting groove 302. A limiting strip 324 is provided on the side wall of the inflatable sealing ring 323 to engage with the limiting groove 303. The cross-section of the limiting strip 324 is barbed.

[0041] The basin body 321 can be integrally cast from aluminum alloy or cast iron using a mold, thereby eliminating the seam defects present in a split structure and preventing gas leakage from the seams. The mounting ring 322 can be connected to the basin body 321 by bolt fastening, and its annular inner cavity forms the bottom boundary of the working chamber 301. The inflatable sealing ring 323 is an expandable annular elastomer, which can be implemented using a hollow silicone tube. After inflation, it expands radially to form a sealing interface. The mounting groove 302 is a groove structure extending circumferentially along the mounting ring 322, used to constrain the initial position of the inflatable sealing ring 323.

[0042] When the printing table 32 aligns with the printing table 33, the inflatable sealing ring 323 on the mounting ring seat 322 is in an uninflated state. At this time, a gap remains between the limiting ring plate 332 and the mounting ring seat 322 to facilitate equipment alignment. After the inflation system is started, the inflatable sealing ring 323 expands radially, and its top forms a surface contact with the lower surface of the limiting ring plate 332. Due to the rigid support characteristics of the limiting ring plate 332, the inflatable sealing ring 323, after being deformed under pressure, uniformly fills the microscopic gaps between the contact surfaces, forming a continuous sealing band. After the vacuum pump 1 is started, the negative pressure in the working chamber 301 further promotes the tight fit between the inflatable sealing ring 323 and the limiting ring plate 332, forming a double sealing guarantee.

[0043] The limiting strip 324 is a protruding structure extending circumferentially along the inflatable sealing ring 323. It can be integrally molded with the sealing ring using a rubber molding process. Its barbed cross-section exhibits a geometric shape where the cross-sectional width gradually decreases in the embedding direction, forming a one-way locking anti-detachment structure. Specifically, the barbed cross-section of the limiting strip 324 is a triangular or trapezoidal tapering shape. This geometric shape generates radial expansion force when the inflatable sealing ring 323 expands, causing the limiting strip 324 to form a wedge-shaped locking effect with the sidewall of the limiting groove 303.

[0044] When the inflatable sealing ring 323 is not inflated, the limiting strip 324 is naturally contracted and embedded in the limiting groove 303. At this time, the printing table 32 can slide freely on the machine body 31. When the printing table 32 slides directly under the printing table 33, the inflatable sealing ring 323 can be inflated and sealed. During the inflation and expansion process, the sealing ring body expands radially. At this time, the inclined surface of the barbed limiting strip 324 contacts the inner wall of the limiting groove 303, and an outward squeezing force is generated as the air pressure increases. Due to the geometric characteristics of the barbed cross section, this squeezing force is converted into friction and mechanical interlocking force between the limiting strip 324 and the limiting groove 303, effectively resisting the axial displacement of the inflatable sealing ring 323.

[0045] The wire mesh assembly 34 includes a wire mesh frame 341, a wire mesh body 342, and a lifting mechanism 343. The lifting mechanism 343 is a cylinder and is fixed inside the mounting frame 331. The output end of the cylinder is fixedly connected to the wire mesh frame 341. The wire mesh body 342 and the wire mesh frame 341 are connected by a plug-in joint for easy disassembly. The lifting mechanism 343 drives the wire mesh frame 341 to extend / retract into the mounting frame 331. There are four lifting mechanisms 343 arranged in a rectangular pattern around the wire mesh frame 341 to achieve stable lifting and lowering of the wire mesh frame 341.

[0046] When the screen printing body 342 needs to be replaced, the lifting mechanism 343 drives the screen printing frame 341 to extend from the mounting frame 331 to a predetermined height, allowing the operator to directly access the screen printing body 342. The old screen printing body 342 is then detached from the screen printing frame 341. After the new screen printing body 342 is fixed to the screen printing frame 341 using the same connection method, the lifting mechanism 343 retracts the screen printing frame 341 back into the mounting frame 331, preventing interference with the moving printing table 32.

[0047] Several infrared sensors 36 are installed on the machine body 31 to sense whether the screen frame 341 extends or retracts into the mounting frame 331. Their installation positions correspond to the movement trajectory of the screen frame 341, and a signal is triggered when the screen frame 341 moves to a set position. Specifically, when the lifting mechanism 343 drives the screen frame 341 to extend out of the mounting frame 331, the infrared sensors 36 detect that the screen frame 341 is in the extended state and generate a signal. This signal is transmitted to the equipment control system to lock the sliding mechanism of the printing table 32, preventing it from sliding into the bottom of the mounting frame 331. When the screen frame 341 is fully retracted into the mounting frame 331, the infrared sensors 36 detect the retracted state and release the lock, allowing the printing table 32 to slide under the printing table 33 for printing. By monitoring the position of the screen frame 341 in real time and controlling the movement of the printing table 32 in conjunction with this monitoring, mechanical collisions due to positional conflicts during movement are avoided.

[0048] A spring connects the wire mesh frame 341 to the mounting frame 331, with one spring corresponding to each lifting mechanism 343. The spring undergoes elastic deformation when the lifting mechanism 343 drives the wire mesh frame 341 to move, and the preload force counteracts the inertial force or external disturbance force generated during the movement of the wire mesh frame 341. Driven by the lifting mechanism 343, the wire mesh frame 341 moves vertically along the inner wall of the mounting frame 331, and the preload force of the spring constrains its lateral displacement.

[0049] Specifically, when the lifting mechanism 343 drives the screen frame 341 to move upward, the spring undergoes tensile deformation due to the upward movement of the screen frame 341. Its restoring force acts on the screen frame 341, suppressing the shaking caused by mechanical clearance at the connection between the output end of the lifting mechanism 343 and the screen frame 341. When the screen frame 341 moves downward, the spring is compressed and stores elastic potential energy. When the lifting mechanism 343 stops moving, the spring eliminates the inertial displacement of the screen frame 341 through elastic rebound. During the printing process, the pressure applied by the squeegee to the screen body 342 will cause the screen frame 341 to be subjected to lateral force. At this time, the spring counteracts this force through lateral preload, preventing the screen frame 341 from rigidly colliding with the inner wall of the mounting frame 331.

[0050] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any ordinary changes and substitutions made by those skilled in the art within the scope of the technical solution of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A thick-film vacuum printing apparatus, comprising a vacuum pump, a vacuum tank, and a printing machine, wherein the printing machine has a working chamber, and the vacuum tank is connected to the working chamber and the vacuum pump via a pipeline, characterized in that, The printing machine includes a printing plate, a printing table, and a screen assembly. The working chamber is formed by the printing plate and the printing table working together, and the working chamber can be evacuated by a vacuum tank to form a vacuum chamber. The screen assembly is installed on the printing table and placed inside the working chamber.

2. The thick film vacuum printing equipment according to claim 1, characterized in that, The printing table includes a basin body, a mounting ring seat, and an inflatable sealing ring. The mounting ring seat is fixed to the top of the basin body and has a mounting groove for embedding the inflatable sealing ring. The printing table includes a mounting frame and a limiting ring plate, the limiting ring plate being fixed to the bottom of the mounting frame. After the inflatable sealing ring is inflated, it comes into contact with the limiting ring plate and is used to seal the working cavity.

3. The thick film vacuum printing equipment according to claim 2, characterized in that, The wire mesh assembly includes a wire mesh frame, a wire mesh body, and a lifting mechanism. The lifting mechanism is fixed in the mounting frame, and its output end is connected to the wire mesh frame. The wire mesh body is detachably connected to the wire mesh frame, and the lifting mechanism drives the wire mesh frame to extend / retract into the mounting frame.

4. The thick film vacuum printing equipment according to claim 3, characterized in that, The printing equipment also includes a machine body, a printing table fixed on the machine body, a printing plate slidably connected to the machine body, and a printing plate that can slide to the bottom of the printing table and cooperate with the printing table.

5. A thick film vacuum printing apparatus according to claim 2 or 4, characterized in that, A limiting groove is provided in the installation groove, and a limiting strip is provided on the side wall of the inflatable sealing ring to engage with the limiting groove. The cross-section of the limiting strip is barbed.

6. A thick film vacuum printing apparatus according to claim 5, characterized in that, The printing table also includes a sealing cover, which is movably installed on the top of the mounting frame and seals the top of the mounting frame. The sealing cover is made of a transparent material.

7. A thick film vacuum printing apparatus according to claim 3, characterized in that, The lifting mechanism is a cylinder or a motor.

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