Dynamic electrostatic attaching device and method for roll-to-roll vacuum coating

Abstract

The dynamic electrostatic attaching device comprises a vacuum cavity, a magnetron sputtering evaporation source is arranged in the vacuum cavity, an insulation cooling main roller is arranged above the magnetron sputtering evaporation source, a thin film is led out from an unwinding roller and wound on a winding roller through the insulation cooling main roller, and the winding roller is connected with the magnetron sputtering evaporation source. The insulation cooling main roller is connected to a positive output end / or a negative output end of a controllable bias power supply; and the dynamic charge closed-loop control unit is used for monitoring and dynamically adjusting the charge state on the surface of the thin film in real time. On the basis of realizing large-area and no-damage tight attachment of the film and the cooling roller, the charge quantity on the surface of the film is automatically and accurately maintained in a preset safe working window through real-time monitoring and feedback adjustment, so that the dielectric breakdown risk caused by overhigh charge is synchronously prevented, and the service life of the film is prolonged. And the problems of adhesive force failure and heat dissipation deterioration caused by too low charges are solved.

Description

Technical Field

[0001] This invention relates to the fields of vacuum coating technology and roll-to-roll manufacturing, and particularly to a dynamic electrostatic bonding device and method for roll-to-roll vacuum coating. Background Technology

[0002] In roll-to-roll vacuum coating processes, physical vapor deposition techniques such as magnetron sputtering and thermal evaporation are commonly used to deposit functional layers onto flexible thin films (such as polyethylene terephthalate (PET) and polyimide (PI)). This process involves intense plasma irradiation and particle bombardment, generating a large amount of heat and causing the film temperature to rise rapidly.

[0003] For films with poor temperature resistance and sensitive surfaces, effective thermal management is crucial. Current technologies primarily rely on two methods to achieve film adhesion to cooling rollers:

[0004] 1. Mechanical pressing: Pressure is applied using pressure rollers. However, excessive pressure can easily cause scratches on the film, generate internal stress or plastic deformation, and is especially unsuitable for ultra-thin and easily stretchable flexible substrates.

[0005] 2. Negative pressure adsorption: Micropores are created on the surface of the cooling roller and connected to a vacuum system. This method has a complex structure, is difficult to seal, has high maintenance costs, and its adsorption force is limited in a vacuum environment. If the film surface is uneven or contains tiny particles, local air gaps can easily form, severely reducing heat transfer efficiency.

[0006] Both mechanical pressing and negative pressure adsorption are open-loop, passive adhesion methods, which cannot dynamically adjust the adhesion force according to the process conditions during long-term, high-power continuous coating processes. This leads to two core problems: First, insufficient adhesion force can cause the film to overheat, deform, or even burn through due to poor heat dissipation; second, if the initial settings or process disturbances result in excessive adhesion force (such as excessive charge in electrostatic adsorption), it may cause dielectric breakdown, damaging the film or equipment. Summary of the Invention

[0007] This invention provides a system that can provide uniform, controllable, dynamically adjustable, and mechanically damage-free adhesion force, and has real-time monitoring and intelligent maintenance capabilities, to ensure high-yield and high-stability roll-to-roll vacuum coating production.

[0008] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0009] A dynamic electrostatic attachment device for roll-to-roll vacuum coating includes a vacuum chamber, a magnetron sputtering evaporation source inside the vacuum chamber, an insulating cooling main roller above the magnetron sputtering evaporation source, a take-up roller and an unwinding roller on both sides of the insulating cooling main roller, a film being drawn out from the unwinding roller, passing through the insulating cooling main roller and being wound onto the take-up roller, the insulating cooling main roller being connected to the positive output terminal / or negative output terminal of a controllable bias power supply, used to generate an electrostatic field between the insulating cooling main roller and the moving film, causing the film to be electrostatically adsorbed onto the surface of the insulating cooling main roller;

[0010] It also includes a dynamic charge closed-loop control unit, which is used to monitor and dynamically adjust the charge state of the thin film surface in real time.

[0011] Further technology of the present invention:

[0012] Preferably, the insulating cooling main roller has a roller body made of metal, an internal circulating cooling medium, and a ceramic layer covering the roller surface.

[0013] Preferably, the dynamic charge closed-loop control unit includes:

[0014] At least one surface potential sensor is used to monitor the potential value V on the thin film surface in real time. s ;

[0015] At least one charge-controlled ion source, the ion beam outlet of which faces the surface of the film and is arranged in front of the path of the film entering the electrostatic adsorption zone of the insulating cooling main roller;

[0016] A controller, which has a preset high threshold voltage V corresponding to the film's secure attachment potential. high With low potential threshold V low ;

[0017] The controller is configured to receive the potential value V monitored by the surface potential sensor. s Signal, and the potential value V s With the high potential threshold V high and low threshold potential V low A comparison is made; based on the comparison result, a control command is output to the charge-controlled ion source and / or the insulating cooling main roller to adjust the potential value V. s Maintained at a potential high threshold V high and low threshold potential V low Within the defined range.

[0018] Preferably, it also includes a thin-film conductive roller connected to the positive output terminal / or negative output terminal of a controllable bias power supply. The thin-film conductive roller is located on the path of the thin film entering the insulating cooling main roller and maintains electrical contact with the front side of the thin film to be coated.

[0019] Preferably, it also includes a pre-cleaning / neutralizing ion source, which is located upstream of the film conductive roller and is used to remove foreign charge from the surface of the film before it enters the main system.

[0020] Preferably, it also includes a post-stripping neutralization ion source, which is located at the position where the film leaves the cooling main roller, and is used to completely neutralize the residual charge on the film surface.

[0021] The present invention also provides a dynamic electrostatic bonding method for roll-to-roll vacuum coating, comprising the following steps:

[0022] S1: Based on the dielectric strength of the thin film material and the required minimum adhesion force, set a safe control window [V] for the thin film surface potential in the controller. low V high ];

[0023] S2: Start the insulating cooling main roller and the film conductive roller, so that the film is electrostatically adsorbed onto the surface of the insulating cooling main roller;

[0024] S3: During the coating process, the surface potential V of the thin film is acquired in real time by the surface potential sensor. s ;

[0025] S4: The V s With the V low V high Perform real-time comparisons and judgments;

[0026] S5: Based on the judgment result of step S4, the controller feeds back and controls the operating parameters of the charge-controlled ion source and / or controls the electric field strength of the insulating cooling main roller and the thin-film conductive roller, so that V s Dynamically adjusted and maintained in the safety control window [V] low V high ]Inside.

[0027] Furthermore, the specific adjustment logic for step S5 is as follows:

[0028] When V s < V low At this time, the controller drives the charge-controlled ion source to increase the implantation of ions of the same polarity onto the film surface, thereby increasing the bias voltage V of the insulating cooling main roller and / or the film conductive roller. b ;

[0029] When V s > V high At this time, the controller drives the charge-controlled ion source to reduce ion implantation, implant reverse polarity ions, or shut down directly, thereby reducing the bias voltage V of the insulating cooling main roller and / or the thin film conductive roller. b .

[0030] The beneficial effects of this invention are:

[0031] This invention achieves large-area, damage-free, and tight adhesion between the film and the cooling roller. Through real-time monitoring and feedback adjustment, it automatically and precisely maintains the amount of charge on the film surface within a preset safe working window, thereby simultaneously preventing the risk of dielectric breakdown due to excessive charge and the problems of adhesion failure and heat dissipation deterioration due to insufficient charge. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of a dynamic electrostatic bonding device for roll-to-roll vacuum coating;

[0034] The markings in the diagram are: 1-vacuum chamber; 2-unwinding roller; 3-rewinding roller; 4-insulating cooling main roller; 5-film; 6-film conductive roller; 7-pre-cleaning / neutralizing ion source; 8-charge-controlled ion source; 9-post-peeling neutralizing ion source; 10-surface potential sensor; 11-magnetron sputtering evaporation source. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0036] Example: Figure 1 As shown, the present invention provides a dynamic electrostatic attachment device for roll-to-roll vacuum coating, comprising a vacuum chamber 1, a magnetron sputtering evaporation source 11 disposed within the vacuum chamber, an insulating cooling main roller 4 disposed above the magnetron sputtering evaporation source 11, a take-up roller 3 and an unwinding roller 2 disposed on both sides of the insulating cooling main roller 4, a film 5 being led out from the unwinding roller 2, and wound onto the take-up roller 3 via the insulating cooling main roller 4, the insulating cooling main roller 4 being connected to the positive output terminal / or negative output terminal of a controllable bias power supply, used to generate an electrostatic field between the insulating cooling main roller 4 and the moving film 5, so that the film 5 is electrostatically adsorbed onto the surface of the insulating cooling main roller 4;

[0037] Electrostatic adsorption enables the film 5 to achieve full molecular-level close contact with the insulating cooling main roller 4, effectively eliminating macroscopic and microscopic air gaps, minimizing thermal resistance, and providing the best heat dissipation guarantee for the film 5 with poor temperature resistance.

[0038] The insulating cooling main roller 4 has a roller body made of metal, an internal circulating cooling medium, and a ceramic layer covering the roller surface.

[0039] It also includes a dynamic charge closed-loop control unit, which is used to monitor and dynamically adjust the charge state on the surface of the thin film 5 in real time.

[0040] It also includes a thin film conductive roller 6, which is connected to the positive output terminal / or negative output terminal of a controllable bias power supply. The thin film conductive roller 6 is located on the path of the thin film 5 entering the insulating cooling main roller 4 and maintains electrical contact with the front side of the thin film 5 to be coated.

[0041] The insulating cooling main roller 4 and the film conductive roller 6 are used to create an electrostatic field between the insulating cooling main roller 4 and the traveling film 5, relying on electrostatic attraction to make the film 5 tightly adhere to the surface of the insulating cooling main roller 4. Based on Maxwell's stress principle, when the film 5 passes between the conductive roller and the main roller, a charge distribution of opposite polarities is formed on both sides of the film 5, generating a strong electrostatic attraction force that pulls the film 5 uniformly toward the surface of the insulating cooling main roller 4.

[0042] It also includes a pre-cleaning / neutralizing ion source 7, which is located upstream of the film conductive roller 6 and is used to remove foreign charges from the surface of the film 5 before it enters the main system, so as to normalize the initial state.

[0043] It also includes a post-peeling neutralization ion source 9, which is located at the position where the film 5 leaves the cooling main roller, and is used to completely neutralize the residual charge on the surface of the film 5 to prevent electrostatic interference with winding and subsequent processes.

[0044] Furthermore, the dynamic charge closed-loop control unit includes:

[0045] At least one surface potential sensor 10 is used to monitor the potential value Vs on the surface of the thin film 5 in real time;

[0046] At least one charge-controlled ion source 8, whose ion beam outlet faces the surface of the film 5 and is arranged in front of the path of the film 5 entering the electrostatic adsorption zone of the insulating cooling main roller 4;

[0047] A controller, which has a preset high threshold voltage V corresponding to the film's secure attachment potential. high With low potential threshold V low ;

[0048] The controller is configured to receive the potential value V monitored by the surface potential sensor. sSignal, and the potential value V s With the high potential threshold V high and low threshold potential V low A comparison is made; based on the comparison result, a control command is output to the charge-controlled ion source and / or the insulating cooling main roller to adjust the potential value V. s Maintained at a potential high threshold V high and low threshold potential V low Within the defined range.

[0049] When V s < V low At this time, the controller drives the charge-controlled ion source to increase the implantation of ions of the same polarity onto the film surface, thereby increasing the bias voltage V of the insulating cooling main roller and / or the film conductive roller. b ;

[0050] When V s > V high At this time, the controller drives the charge-controlled ion source to reduce ion implantation, implant reverse polarity ions, or shut down directly, thereby reducing the bias voltage V of the insulating cooling main roller and / or the thin film conductive roller. b .

[0051] This system features a dual-threshold safety protection mechanism. Once the system detects that charge accumulation is approaching the risk of breakdown (V... s \toV high ), immediately and automatically perform neutralization or voltage reduction operations; when charge loss leads to insufficient adhesion (V s \to V low If the electrostatic discharge occurs, a replenishment mechanism will be immediately activated. This fundamentally eliminates the possibility of batch-scale film damage or process interruption caused by electrostatic discharge.

[0052] It should be noted that V high Based on the dielectric strength Eb and thickness H of thin film 5, V is set. high Typically, the safety factor S is set at 50%-70% of the breakdown voltage to prevent electrical breakdown. low Determined experimentally based on the minimum adhesion force required to ensure effective heat conduction, this is used to prevent adhesion failure.

[0053] In this embodiment, V high =Eb*H*S,V low Determined through testing.

[0054] Based on the equipment structure and equivalent capacitance model, the principle of electrostatic adsorption can be divided into two core stages: charge assignment and electrostatic induction adsorption, as detailed below:

[0055] 1. Charge Assignment Stage

[0056] The film 5 is led out from the self-unwinding roller 2. After the surface static electricity is eliminated by the pre-cleaning / neutralizing ion source 7, its front side comes into contact with the film conductive roller 6 with positive high voltage. The front side of the film 5 is given a stable positive charge. The positive terminal of the bias power supply is connected to the film conductive roller 6, and the negative terminal is connected to the insulating cooling main roller 4, which establishes the charge basis for subsequent electrostatic adsorption.

[0057] 2. Electrostatic induction and adsorption stage

[0058] After passing below the charge-controlled ion source 8, the positively charged film 5 enters the attachment area of ​​the insulating cooling main roller 4. The insulating cooling main roller 4 carries a negative high voltage (or is grounded). When the positively charged film 5 approaches the main roller, due to electrostatic induction, the side of the film 5 that is close to the insulating cooling main roller 4 induces a negative charge with the opposite polarity to that of the main roller, while the other side that is away from the insulating cooling main roller 4 retains a positive charge.

[0059] Opposite charges attract each other. The film 5 is firmly adsorbed onto the surface of the insulating cooling main roller 4 by the electrostatic attraction formed by the induced negative charge and the negative high voltage of the insulating cooling main roller 4, thus completing the adhesion requirements of the coating process.

[0060] 3. Subsequent charge processing

[0061] After coating is completed, the film 5 is detached from the insulating cooling main roller 4, and after being peeled off, the residual static electricity on the surface is eliminated by the neutralizing ion source. Finally, it is collected by the take-up roller 3, completing the entire process.

[0062] Taking the preparation of composite aluminum foil from a 6μm thick PET film as an example, the insulating cooling main roller is connected to the negative output terminal of the bias power supply, and the film conductive roller is connected to the positive output terminal of the bias power supply.

[0063] S1: Security window settings.

[0064] The dielectric strength of PET film is approximately 100 kV / mm, and the theoretical average breakdown voltage is approximately E. b (Thin film material) * H (thick film thickness), i.e., 0.1 kV / μm × 6 μm = 0.6 kV. Setting the safety factor to 0.6, based on V... high =E b (Thin film material) * H (thick film thickness) * S, we can get V high =0.36kV low The voltage was tested to be 100V.

[0065] S2: Electrostatic attachment start-up.

[0066] S21: Set the cavity vacuum to the preset level of 1*10. -1 Pa.

[0067] S22: Start cooling water circulation.

[0068] S23: Turn on the pre-cleaning / neutralization ion source and the post-stripping neutralization ion source to treat the surface of the film in operation.

[0069] S24: Start the bias power supply and set the voltage.

[0070] S25: Start the surface potential sensor and central controller.

[0071] S26: Control: Read the initial voltage, within the safe window. Activate the charge-controlled ion source (argon, low current mode).

[0072] S27: Start the magnetron sputtering coating process. As the coating process proceeds, the plasma environment causes the surface charge of the thin film to be partially neutralized.

[0073] S3: Real-time potential monitoring. The surface potential value Vs of the thin film is continuously acquired through a surface potential sensor.

[0074] S4: Potential state determination. Vs and preset V low =100V, V high A comparison is made at 360V to determine whether it is within a safe range.

[0075] S5: Dynamic Feedback Adjustment. Throughout the process, if Vs exceeds 360V for any reason, the controller will immediately shut down the charge-controlled ion source and reduce the bias power supply voltage until Vs falls back to the safe zone. If Vs falls below 100V for any reason, the bias voltage will be increased. The process ends. After coating is completed, ensure that the post-peel neutralization ion source continues to operate to ensure that the film is electrically neutral before winding.

[0076] Through the closed-loop control described above, the film maintains optimal adhesion to the cooling roller throughout the entire coating process, ensuring uniform heat dissipation and eliminating the risk of breakdown.

[0077] In this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0078] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0079] The above description is merely an example and illustration of the structure of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A dynamic electrostatic attachment device for roll-to-roll vacuum coating, characterized in that, The vacuum chamber comprises a magnetron sputtering evaporation source, an insulating cooling main roller above the magnetron sputtering evaporation source, and a winding roller and an unwinding roller on both sides of the insulating cooling main roller. The film is wound on the winding roller after being drawn out from the unwinding roller and passing through the insulating cooling main roller. The insulating cooling main roller is connected to the positive output terminal and / or the negative output terminal of a controllable bias power supply, so as to generate an electrostatic field between the insulating cooling main roller and the film in motion, and to electrostatically adsorb the film on the surface of the insulating cooling main roller. The dynamic charge closed-loop control unit is further used for monitoring and dynamically adjusting the charge state of the film surface in real time.

2. The dynamic electrostatic attachment device and method for roll-to-roll vacuum coating of claim 1, wherein: The insulating cooling main roller is made of metal, has a circulating cooling medium in the inside, and has a ceramic layer on the roller surface.

3. The dynamic electrostatic attachment device and method for roll-to-roll vacuum coating of claim 1, wherein: The dynamic charge closed-loop control unit comprises: at least one surface potential sensor for monitoring the potential value V of the film surface in real time s ; At least one charge regulation ion source, whose ion beam outlet is directed towards the film surface and is arranged in front of the path of the film entering the electrostatic adsorption area of the insulating cooling main roller. A controller, in which a high potential threshold value V corresponding to the thin film security patch is preset high and a low potential threshold value V low ; The controller is configured to receive the potential value V s monitored by the surface potential sensor, compare the potential value V s with the high potential threshold V high and the low potential threshold V low , and output a control instruction to the charge regulating ion source and / or the insulated cooling main roll according to the comparison result, so that the potential value V s is maintained within the range defined by the high potential threshold V high and the low potential threshold V low .

4. The dynamic electrostatic attachment device and method for roll-to-roll vacuum coating of claim 3, wherein: The film conductive roller is connected to the positive output terminal and / or the negative output terminal of a controllable bias power supply, and is arranged in the path of the film entering the insulating cooling main roller, and is in electrical contact with the front surface of the film to be coated.

5. The dynamic electrostatic attachment device and method for roll-to-roll vacuum coating of claim 4, wherein: The pre-cleaning / neutralizing ion source is arranged upstream of the film conductive roller, and is used for removing surface foreign charges before the film enters the main system.

6. The dynamic electrostatic attachment device and method for roll-to-roll vacuum coating of claim 5, wherein: The post-stripping neutralizing ion source is arranged at the position where the film leaves the cooling main roller, and is used for completely neutralizing the residual charges on the film surface.

7. A dynamic electrostatic attachment method using the dynamic electrostatic attachment device for roll-to-roll vacuum coating according to claim 6, characterized in that, The method comprises the following steps: S1: Set a safe control window of the surface potential of the thin film [V] in the controller according to the dielectric strength of the thin film material and the required minimum adhesion force low , V high ] S2: Start the insulating cooling main roller and the film conductive roller, so as to electrostatically adsorb the film on the surface of the insulating cooling main roller. S3: During the coating process, the surface potential of the thin film V is acquired in real time by the surface potential sensor s ; S4: comparing the V s with the V low , V high in real time and making a judgment. S5: based on the judgment result of step S4, feedback control the operation parameters of the charge regulating ion source and / or control the field strength of the insulating cooling main roller and the thin film conductive roller through the controller, so that V s is dynamically adjusted and maintained within the safety control window [V low , V high ].

8. The dynamic electrostatic attachment method for roll-to-roll vacuum coating according to claim 7, wherein, The specific adjustment logic of step S5 is as follows: When V s < V low , the controller drives the charge regulation ion source to increase the injection of ions of the same polarity to the film surface, and increases the bias voltage V b of the insulating cooling main roller and / or the conductive roller of the film. When V s > V high , the controller drives the charge regulation ion source to reduce ion injection, inject ions of opposite polarity, or directly shut down, reducing the bias voltage V b of the insulating cooling main roller and / or the conductive film roller.

Images