Stacked hot pressing method and stacked hot pressing device

Abstract

The present invention belongs to the technical field of glass hot pressing, and particularly relates to a stacked hot pressing method and a stacked hot pressing device. The stacked hot pressing method comprises the following steps: heating, placing a lower die base on a heating structure, stacking a plurality of templates in sequence along the vertical direction, and arranging glass wafers between any two adjacent templates; the heating structure heats each glass wafer to a predetermined temperature in a vacuum environment or an inert gas environment; hot pressing, using a driving structure to press an upper die head against the lower die base to press each template, so that each glass wafer replicates a micro-nano structure; cooling, cooling the temperature of each glass wafer at a predetermined cooling rate; demolding, taking out each glass wafer formed by hot pressing. The present invention can improve the hot pressing efficiency of glass wafers.

Description

Technical Field

[0001] The present invention belongs to the technical field of glass hot pressing, and particularly relates to a stacked hot pressing method and a stacked hot pressing device. Background Art

[0002] Glass micro-nano structure devices such as micro-nano optical elements, micro-optical electro-mechanical systems (MOEMS), and microfluidic chips have the advantages of miniaturization, integration, high sensitivity, low power consumption, etc., and are widely used in new-generation optical systems, information communication, mechatronics, biochemistry and other fields. In recent years, with the development of society and the update and iteration of technologies, the requirements for the shape accuracy of glass micro-nano structure devices are getting higher and higher, and the demand is increasing day by day. Breaking through the high-precision, high-efficiency, and low-cost manufacturing technology of glass micro-nano structures has become a major demand in the field of micro-nano manufacturing.

[0003] At present, the manufacturing methods of glass micro-nano structure devices include micro-milling technology, ultra-precision grinding technology, laser direct writing technology, ultraviolet lithography technology, ion beam lithography technology, electron beam lithography technology, and hot embossing technology, etc. Among them, the hot embossing technology has the advantages of cross-scale manufacturing from micro to nano, high surface replication fidelity, relatively high manufacturing efficiency, flexible process, low carbon and environmental protection. Moreover, combined with ultra-precision mold processing technology, the hot embossing technology is expected to become an effective way to solve the high-efficiency and low-cost manufacturing of high-quality glass micro-nano structure devices.

[0004] However, the current traditional hot pressing method is generally single-device forming, and only one glass wafer can be hot pressed and formed at a time, resulting in low manufacturing efficiency. Summary of the Invention

[0005] The purpose of the embodiments of the present application is to provide a stacked hot pressing method, aiming to solve the problem of how to improve the efficiency of glass wafer molding.

[0006] To achieve the above purpose, the technical solution adopted by the present application is:

[0007] In a first aspect, a stacked hot pressing method is provided for hot pressing and forming a glass wafer. The stacked hot pressing method includes the following steps:

[0008] Prepare a lower die base, an upper die head located above the lower die base, and a template provided with a micro-nano structure and located on the lower die base;

[0009] Heating: Place the lower die base on a heating structure, stack a plurality of the templates in sequence in the vertical direction, and a glass wafer is disposed between any two adjacent templates; the heating structure heats each glass wafer to a predetermined temperature in a vacuum environment or an inert gas environment;

[0010] Hot pressing, using a driving structure to press the upper die head against the lower die base for each template, so that each glass wafer replicates the micro-nano structure;

[0011] Cooling, cooling the temperature of each glass wafer at a predetermined cooling rate;

[0012] Demolding, taking out each hot-pressed glass wafer.

[0013] In some embodiments, the micro-nano structure includes a micro-structure with a size in the micron range and / or a nano-structure with a size in the nano range.

[0014] In some embodiments, the size of the micro-nano structure on each template gradually decreases from bottom to top.

[0015] In some embodiments, the micro-nano structure is located on the upward-facing surface of the template.

[0016] In some embodiments, a positioning sleeve with a forming cavity is prepared, the upper die head is adapted to the forming cavity and is partially slidably disposed in the forming cavity, and each template is placed in the forming cavity.

[0017] In some embodiments, the driving structure includes a force-applying component and a lifting platform located below the force-applying component and connected to the heating structure. The force-applying component includes a first-stage gravity unit slidably disposed in the vertical direction and connected to the upper die head, and a second-stage gravity unit slidably disposed in the vertical direction and located above the first-stage gravity unit; the hot pressing step includes the following steps:

[0018] S21: The lifting platform drives the lower die base to move upward a first distance, and the upper die head abuts against the first-stage gravity unit, so that the first-stage gravity unit is loaded on the upper die head;

[0019] S22: The lifting platform drives the lower die base to continue moving upward a second distance, so that both the first-stage gravity unit and the second-stage gravity unit are loaded on the upper die head.

[0020] The demolding step includes the following steps:

[0021] S31: The lifting platform drives the lower die base to move downward the second distance, so that the lower die base unloads the imprinting force of the second-stage gravity unit while retaining the imprinting force of the first-stage gravity unit;

[0022] S32: The lifting platform drives the lower die base to continue moving downward the first distance, so that the lower die base unloads the imprinting force of the first-stage gravity unit.

[0023] In some embodiments, the stacked hot pressing method is characterized in that: in the step S31, the upper die head and each glass wafer are cooled at a first cooling rate; in the step S32, the upper die head and each glass wafer are cooled at a second cooling rate, and the second cooling rate is greater than the first cooling rate.

[0024] In some embodiments, the force applying assembly further includes a support frame, and both the first-stage gravity unit and the second-stage gravity unit are slidably connected to the support frame.

[0025] In a second aspect, a stacked hot pressing device is provided, which is used to implement the stacked hot pressing method.

[0026] The beneficial effect of the present application is that: in the stacked hot pressing method, multiple templates are stacked, and a glass wafer is arranged between any two adjacent templates, so that multiple glass wafers are stacked. Then, the upper die head is pressed against the lower die base to press the glass wafers through the driving structure. The glass wafers are at the glass transition temperature, so that the micro-nano structures on the templates can be replicated. Multiple glass wafers can be formed by one hot pressing, thereby improving the hot pressing efficiency. Description of the Drawings

[0027] To more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for use in the embodiments or exemplary technical descriptions. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0028] Figure 1 is a flowchart of the stacked hot pressing method provided by the embodiment of the present application;

[0029] Figure 2 is Figure 1 a schematic diagram of the change curves of the temperature, pressure and displacement of the glass wafer in the stacked hot pressing method;

[0030] Figure 3 is a three-dimensional structural diagram of the stacked hot pressing device provided by another embodiment of the present application;

[0031] Figure 4 is a three-dimensional structural diagram of the upper die head and the positioning sleeve provided by another embodiment of the present application;

[0032] Figure 5 is Figure 4 a cross-sectional view of;

[0033] Figure 6 is Figure 3 a structural diagram of the force applying assembly of.

[0034] Among them, each reference numeral in the figure:

[0035] 100, stacked hot pressing device; 101, hot pressing box body; 111, vacuum chamber; 200, driving structure; 201, force applying component; 202, lifting table; 300, heating structure; 2011, first-stage gravity unit; 2012, second-stage gravity unit; 2013, guide post; 2014, pressure ball; 401, positioning sleeve; 402, upper die head; 403, template; 404, glass wafer; 405, lower die base; 406, concave cavity; 211, first slide plate; 210, first weight; 221, second slide plate; 220, second weight; Detailed implementation manners

[0036] In order to make the objectives, technical solutions and advantages of the present application clearer and more understandable, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present application.

[0037] It should be noted that when a component is referred to as being "fixed to" or "disposed on" another component, it can be directly on the other component or indirectly on the other component. When a component is referred to as being "connected to" another component, it can be directly or indirectly connected to the other component. The orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the present application. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances. The terms "first" and "second" are only used for the purpose of convenient description and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of technical features. The meaning of "a plurality" is two or more, unless otherwise specifically defined.

[0038] Please refer to Figures 1 to 3 , the embodiment of the present application provides a stacked hot pressing method and a stacked hot pressing device for implementing the same. The stacked hot pressing method is used for hot pressing and forming a glass wafer 404. The glass wafer 404 is an optical glass wafer 404, which has excellent optical transparency and thermal stability and is widely used in the manufacturing of optical devices and the optoelectronic field, such as lasers, optical fiber communication devices, etc.

[0039] Please refer to Figures 1 to 2 , the stacked hot pressing method includes the following steps:

[0040] Please refer to Figures 1 to 2, prepare the lower die base 405, the upper die head 402 located above the lower die base 405, and the template 403 which is provided with micro-nano structures and is located on the lower die base 405; place the lower die base 405, the upper die head 402, and the template 403 in a vacuum environment or an inert gas environment. For example, prepare a hot pressing box 101 which has a vacuum chamber 111 and can evacuate the vacuum chamber 111 or fill it with an inert gas, and then place the lower die base 405, the upper die head 402, and the template 403 in the vacuum chamber 111.

[0041] S1: Heating. Place the lower die base 405 on the heating structure 300. Stack multiple templates 403 vertically in sequence, and a glass wafer 404 is arranged between any two adjacent templates 403 so that multiple glass wafers 404 are stacked. The heating structure 300 heats each glass wafer 404 to a predetermined temperature in a vacuum environment or an inert gas environment and keeps it warm to make the temperature of each glass wafer 404 uniform. The predetermined temperature is the TG temperature of the glass wafer 404, that is, the glass transition temperature, which refers to the temperature at which the glass material changes from a brittle and hard state to a ductile state. For example, the glass transition temperature of BK7 is about 550 degrees.

[0042] It can be understood that the heating structure 300 heats each glass wafer 404, the template 403, and the lower die base 405 to the glass transition temperature.

[0043] S2: Hot pressing. Use the driving structure 200 to press the upper die head 402 towards the lower die base 405 to press each template 403 so that each glass wafer 404 replicates the micro-nano structure of the corresponding template 403. The driving structure 200 presses the upper die head 402 and the lower die base 405 bidirectionally so that compressive stress is applied to each glass wafer 404.

[0044] S3: Cooling. Cool the temperature of each glass wafer 404 at a predetermined cooling rate so that the glass wafer 404 replicated with the micro-structure is annealed. The temperature of the glass wafer 404 can be slowly decreased by reducing the heating power of the heating structure 300. The cooling rate can be 20 degrees per minute or 50 degrees per minute, which can be selected according to the actual situation and is not limited here. Cooling gas can also be used to cool the hot-pressed glass wafer 404 to room temperature.

[0045] S4: Demolding. Take out each hot-pressed glass wafer 404. It can be understood that the driving structure 200 withdraws the imprinting force on each glass wafer 404 so as to take out each hot-pressed glass wafer 404. At this time, the micro-nano structure on the template 403 has been replicated on the glass wafer 404.

[0046] Please refer to Figures 1 to 2, in the stacking hot pressing method provided by the embodiment of the present application, a plurality of templates 403 are stacked, and a glass wafer 404 is arranged between any two adjacent templates 403, so that a plurality of glass wafers 404 are stacked. Then, the upper die head 402 presses the glass wafer 404 against the lower die base 405 through the driving structure 200. The glass wafer 404 is at the glass transition temperature, so that the micro-nano structure on the template 403 can be replicated. Multiple glass wafers 404 can be formed by one hot pressing, thereby improving the hot pressing efficiency.

[0047] Optionally, in the stacking hot embossing method proposed in this embodiment, the single-device forming manufacturing mode is abandoned, and hundreds of micro-nano structure devices are simultaneously formed on multiple glass wafers 404, thereby further greatly improving the manufacturing efficiency.

[0048] Please refer to Figures 3 to 5 , in some embodiments, a positioning sleeve 401 with a forming cavity is prepared. The upper die head 402 is adapted to the forming cavity and is partially slidably arranged in the forming cavity, and each template 403 is placed in the forming cavity.

[0049] Please refer to Figures 3 to 5 , optionally, the positioning sleeve 401 is arranged in the vertical direction. The lower die base 405 and each template 403 are arranged in the forming cavity. The template 403 can be positioned through the forming cavity to prevent the template 403 from moving during the hot pressing process. The lower end of the upper die head 402 is located in the forming cavity to press each template 403 downward.

[0050] In some embodiments, the micro-nano structure includes a micro-structure with a size in the micron range and / or a nano-structure with a size in the nano range.

[0051] Please refer to Figures 3 to 5 , it can be understood that the micro-nano structure is a concave cavity 406 opened on the template 403. A plurality of concave cavities 406 are arranged in an array. The size of the concave cavity 406 includes the depth of the concave cavity 406 and the size of the cross-sectional area. The size can be in the micron range and / or the nano range. The imprinting force presses the softened glass wafer 404 into each concave cavity 406, and the glass wafer 404 fills the concave cavity 406, so that the glass wafer 404 replicates the micro-nano structure on the template 403.

[0052] In some embodiments, the size of the micro-nano structure on each template 403 gradually decreases from bottom to top.

[0053] Please refer to Figures 3 to 5, it can be understood that the side surface of the template 403 contacts the inner wall of the forming cavity, so that the forming cavity can position each template 403. Frictional forces are generated between each template 403 and the inner wall of the forming cavity. As the height decreases, the frictional force increases. That is, the imprinting force borne by the template 403 at the lower end of the positioning sleeve 401 is lower than that of the template 403 at the upper end of the positioning sleeve 401. That is, the imprinting force applied to the upper die head 402 decreases from top to bottom, so that the ability of the imprinting force to drive the glass wafer 404 to fill the concave cavity 406 decreases. By appropriately increasing the size of the concave cavity 406, as the size of the concave cavity 406 increases, it is easier for the glass wafer 404 to fill the "dead corners" in the concave cavity 406, so that the imprinting force can drive the glass wafer 404 to fill the concave cavity 406, ensuring the accuracy and reliability of the hot pressing.

[0054] Please refer to Figures 3 to 5 , in some embodiments, the micro-nano structure is located on the upward-facing surface of the template 403. It can be understood that the glass wafer 404 can fill the concave cavity 406 from top to bottom under the dual action of gravity and imprinting force. During the subsequent pressure holding process, the glass wafer 404 material can continue to flow and fill the concave cavity 406 under the action of gravity without shrinking inward.

[0055] It can be understood that the micro-nano structure can also be formed on the lower surface of the template 403.

[0056] Please refer to Figure 6 , in some embodiments, the driving structure 200 includes a force-applying assembly 201 and a lifting table 202 located below the force-applying assembly 201 and connected to the heating structure 300. The force-applying assembly 201 includes a first-stage gravity unit 2011 slidably arranged in the vertical direction and connected to the upper die head 402, and a second-stage gravity unit 2012 slidably arranged in the vertical direction and located above the first-stage gravity unit 2011; the hot pressing step includes the following steps:

[0057] S21: The lifting table 202 drives the lower die base 405 to move upward a first distance, and the upper die head 402 abuts against the first-stage gravity unit 2011, so that the first-stage gravity unit 2011 loads on the upper die head 402;

[0058] S22: The lifting table 202 drives the lower die base 405 to continue to move upward a second distance, so that both the first-stage gravity unit 2011 and the second-stage gravity unit 2012 load on the upper die head 402;

[0059] S23: Hold the pressure for a predetermined time, such as 0.5 minutes, 2 minutes or 5 minutes, which is not limited here and can be selected according to actual situations.

[0060] Optionally, at the end of the hot pressing step, such as during the pressure holding process of S23, due to the contact between the upper die head 402 and the force applying component 201, heat loss occurs. The power of the heating structure is appropriately increased to supplement the heat loss, so that the glass wafer 404 can fully fill each cavity 406.

[0061] Please refer to Figures 4 to 6 , it can be understood that both the first-stage gravity unit 2011 and the second-stage gravity unit 2012 apply an imprinting force to the glass wafer 404 through their own gravity, without the need for an additional driver, and the force application process is stable and reliable. The structures of the first-stage gravity unit 2011 and the second-stage gravity unit 2012 are similar and both include weights. The imprinting force and the pressure holding force can be precisely controlled by adjusting the gravity of the weights. Using F1-level weights, the theoretical error can be controlled within 1 mN. The moving resolution of the lifting table 202 can reach 50 nm, and the accuracy of the linear encoder can reach 5 nm. The fuzzy PID control algorithm is used to achieve precise loading of the vertical displacement, so as to complete actions such as hot pressing, pressure holding, and demolding.

[0062] Please refer to Figures 4 to 6 , in some embodiments, the force applying component 201 further includes a support frame, and both the first-stage gravity unit 2011 and the second-stage gravity unit 2012 are slidably connected to the support frame.

[0063] Please refer to Figures 4 to 6 , optionally, the support frame includes a plurality of guide posts 2013 arranged in the vertical direction. The first-stage gravity unit 2011 includes a first slide plate 211 and a first weight 210 connected to the first slide plate 211. The second-stage gravity unit 2012 includes a second slide plate 221 and a second weight 220 connected to the second slide plate 221. Both the first slide plate 211 and the second slide plate 221 are slidably connected to each guide post 2013, and the second slide plate 221 is located above the first slide plate 211.

[0064] Please refer to Figures 4 to 6 , optionally, pressure balls 2014 are provided at the lower ends of both the first weight 210 and the second weight 220, so that the first-stage gravity unit 2011 and the second-stage gravity unit 2012 maintain point-to-plane contact through the pressure balls 2014, and the first-stage gravity unit 2011 and the upper die head 402 maintain point-to-plane contact, which is beneficial to making the imprinting force of the first-stage gravity unit 2011 and the imprinting force of the second-stage gravity unit 2012 collinear in the vertical direction and improving the hot pressing accuracy of the glass wafer 404.

[0065] Please refer to Figures 4 to 6, it can be understood that the lifting table 202 drives the heating structure 300 to move upward, and the lower die holder 405, each template 403 and the upper die head 402 move upward together until the upper die head 402 abuts against the pressure ball 2014 of the first-stage gravity unit 2011. The first-stage gravity unit 2011 slides upward along each guide post 2013, so that the gravity of the first-stage gravity unit 2011 is completely applied to each glass wafer 404. The lifting table 202 continues to drive the heating structure 300 to rise until the first slide plate 211 abuts against the pressure ball 2014 on the second weight 220 and jacks up the second-stage gravity unit 2012. The second-stage gravity unit 2012 slides upward along each guide post 2013, so that the imprinting forces (gravity) of the first-stage gravity unit 2011 and the second-stage gravity unit 2012 are both completely applied to each glass wafer 404.

[0066] Please refer to Figures 4 to 6 , in some embodiments, the demolding step includes the following steps:

[0067] S31: The lifting table 202 drives the lower die holder 405 to move downward by the second distance, so that the lower die holder 405 unloads the imprinting force of the second-stage gravity unit 2012 while retaining the imprinting force of the first-stage gravity unit 2011, and the imprinting force of F3 is applied to the surface of the glass wafer 404 to prevent the microstructure of the glass wafer 404 from relaxing in a low-viscosity state, resulting in deformation and damage to the surface of the glass wafer 404 with replicated micro-nano structures. It can be understood that after the upper die head 402 and the lower die holder 405 are closed for a period of time, the heating power of the heating structure 300 and the flow rate of the cooling nitrogen gas filled into the vacuum chamber 111 are adjusted to slowly decrease its temperature, and each glass wafer 404 is cooled and annealed. During the annealing process, the lifting table 202 drives the heating structure to move downward to achieve the unloading of the second-stage gravity unit 2012;

[0068] S32: The lifting table 202 drives the lower die holder 405 to continue to move downward by the first distance, so that the lower die holder 405 unloads the imprinting force of the first-stage gravity unit 2011. When the temperature of the glass wafer 404 reaches TF, the lifting table 202 drives the heating structure 300 to continue to move downward to achieve the unloading of the first-stage gravity unit 2011, and the imprinting force between the upper die head 402 and the lower die holder 405 drops to 0N, but the upper die head 402 with a certain gravity is located on the uppermost template 403, so that the microstructures of each glass wafer 404 remain unchanged in shape. At the same time, the heating power of the ceramic heating sheet of the heating structure 300 is further reduced and the flow rate of the cooling nitrogen gas is increased to increase its cooling rate, so that the temperature of each glass wafer 404 is cooled to T4.

[0069] S33: Each glass wafer 404 is cooled to room temperature T0, and the imprinted glass wafers 404 are taken out and cleaned.

[0070] Please refer to Figures 4 to 6 In some embodiments, in the step S31, the upper die head 402 and the glass wafer 404 are cooled at a first cooling rate; in the step S32, the upper die head 402 and the glass wafer 404 are cooled at a second cooling rate, and the second cooling rate is greater than the first cooling rate. The first cooling rate mainly puts the glass wafer 404 in an annealing state, and the second cooling rate mainly realizes the rapid cooling of the glass wafer 404.

[0071] In some embodiments, in the S1 heating step, the upper die head 402 and the lower die base 405 are kept at the predetermined temperature for a predetermined time. The predetermined time can be 1 min, 3 min or 5 min, and is selected according to the actual situation and is not limited herein.

[0072] Please refer to Figures 3 to 5 After the glass wafer 404 is formed, nitrogen is introduced into the vacuum chamber 111, and the heating power of the heating structure 300 is further reduced and the flow rate of the cooling nitrogen is increased to accelerate the cooling of each glass wafer 404. When the temperature of each glass wafer 404 drops to 200 °C, the vacuum chamber 111 is opened, and each glass wafer 404 is taken out for quality inspection.

[0073] It can be seen therefrom that the stacked hot pressing method can shorten the forming cycle by batch hot pressing, reducing the heat preservation, contact and pressure holding time, accelerating the heating and cooling rates, increasing the demolding temperature, and avoiding multiple taking / putting of the glass wafer 404, thereby improving the manufacturing efficiency.

[0074] Please refer to Figure 2 During the hot pressing of the glass wafer, at time t B , the temperature of the upper die head 402 or the lower die base 405 is heated to T B , that is, the Tg temperature, and heat preservation is carried out from t B to t 2 . At time t D , the pressing force gradually increases until all the first-stage gravity units 2011 and the second-stage gravity units 2012 are loaded. From t E to t 3 , pressure holding is carried out. From t 3 to t F , annealing is carried out, and at the same time, the second-stage gravity unit 2012 is unloaded, and the temperature of the upper die head 402 and the lower die base 405 is reduced to T F . From t F to t4, the first-stage gravity unit is unloaded, and rapid cooling is carried out to T 0 .

[0075] Please refer to Figure 3, the present invention also provides a stacked hot pressing device 100, which is used to implement the above-mentioned stacked hot pressing method. For the specific implementation steps of this method, please refer to the above embodiments. Since this stacked hot pressing device 100 adopts all the technical solutions of the above-mentioned embodiments, it also has all the beneficial effects brought by the technical solutions of the above embodiments, which will not be elaborated here one by one.

[0076] Please refer to Figures 3 to 6 , in some embodiments, the stacked hot pressing device 100 includes: a lower die base 405, a template 403, an upper die head 402, a heating structure 300, and a driving structure 200. The driving structure 200 includes a lifting table 202 with a linear encoder, a displacement table 203 for driving the horizontal movement of the lifting table 202, and a force application component 201 for applying an imprinting force to the upper die head 402. The displacement table 203 is provided with a displacement sensor, and its accuracy can reach 0.1 μm. The lower die base 405 is placed on the heating structure 300. The displacement table 203 is used to drive the lifting table 202 to be located below the force application component 201. The lifting table 202 can drive the heating structure 300 to move in the vertical direction, and the accuracy resolution can reach 0.2 μm through the linear encoder.

[0077] The heating structure 300 includes two silicon nitride ceramic heating sheets, a copper plate, a tungsten plate, and a fused silica sheet. The silicon nitride ceramic heating sheet has excellent high-temperature oxidation resistance, high durability, and high heating power, but there is a problem of uneven surface temperature distribution. Since copper has high thermal conductivity, heat can be quickly transferred from the ceramic heating sheet to the copper plate, and finally a uniform temperature distribution can be obtained on the surface of the copper plate. Moreover, placing a fused silica sheet with extremely low thermal conductivity under the copper plate for heat preservation can reduce heat loss. On the other hand, using a high-strength tungsten plate to cover the copper plate can prevent it from bending and deforming under the action of concentrated force.

[0078] The above are only optional embodiments of the present application and are not used to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the scope of the claims of the present application.

Claims

1. A stacked hot pressing method for hot pressing and forming a glass wafer, characterized in that, the stacked hot pressing method comprises the following steps: Prepare a lower die base, an upper die head located above the lower die base, and a template provided with a micro-nano structure and located on the lower die base; Heating: Place the lower die base on a heating structure. A plurality of the templates are stacked in sequence in the vertical direction, and a glass wafer is provided between any two adjacent templates. The heating structure heats each glass wafer to a predetermined temperature in a vacuum environment or an inert gas environment. The predetermined temperature is the glass transition temperature of the glass wafer, and heat preservation is carried out to make the temperature of each glass wafer uniform; Hot pressing: Use a driving structure to make the upper die head press each template towards the lower die base, so that each glass wafer replicates the micro-nano structure. The micro-nano structure is a concave cavity opened on the template, and a plurality of the concave cavities are arranged in an array; The sizes of the micro-nano structures on each template gradually decrease from bottom to top; The micro-nano structure is located on the upward-facing surface of the template; The driving structure includes a force application component and a lifting table located below the force application component and connected to the heating structure. The force application component includes a first-stage gravity unit slidably arranged in the vertical direction and connected to the upper die head, and a second-stage gravity unit slidably arranged in the vertical direction and located above the first-stage gravity unit. The hot pressing step comprises the following steps: S21: The lifting table drives the lower die base to move upward by a first distance, and the upper die head abuts against the first-stage gravity unit, so that the first-stage gravity unit is loaded on the upper die head; S22: The lifting table drives the lower die base to continue to move upward by a second distance, so that both the first-stage gravity unit and the second-stage gravity unit are loaded on the upper die head, and the power of the heating structure is increased to supplement the loss of heat; Cooling: Cool the temperature of each glass wafer at a predetermined cooling rate; Demolding: Take out each hot-pressed and formed glass wafer.

2. The stacked hot pressing method according to claim 1, characterized in that: The micro-nano structure includes a micro-structure with a micron size and / or a nano-structure with a nano size.

3. The stacked hot pressing method according to claim 1, characterized in that: Prepare a positioning sleeve with a forming cavity. The upper die head is adapted to the forming cavity and is partially slidably arranged in the forming cavity, and each template is placed in the forming cavity.

4. The stacked hot pressing method according to any one of claims 1-3, characterized in that: The demolding step comprises the following steps: S31: The lifting table drives the lower die base to move downward by the second distance, so that the lower die base unloads the imprinting force of the second-stage gravity unit while retaining the imprinting force of the first-stage gravity unit; S32: The lifting table drives the lower die base to continue to move downward by the first distance, so that the lower die base unloads the imprinting force of the first-stage gravity unit.

5. The stacked hot pressing method according to claim 4, characterized in that: In the step S31, the upper die head and each of the glass wafers are cooled at a first cooling rate; in the step S32, the upper die head and each of the glass wafers are cooled at a second cooling rate, and the second cooling rate is greater than the first cooling rate.

6. The stacked hot pressing method according to any one of claims 1-3, characterized in that: The force applying assembly further includes a support frame, and both the first-stage gravity unit and the second-stage gravity unit are slidably connected to the support frame.

7. A stacked hot pressing device, characterized in that it is used to implement the stacked hot pressing method according to any one of claims 1-6.

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