Ultra-thin transparent electromagnetic shielding film and preparation method and device thereof

Abstract

The present application provides an ultra-thin transparent electromagnetic shielding film, a preparation method and a device thereof, which are applied to the technical fields of optical coating materials, electromagnetic shielding films and vacuum coating technologies. Among them, silver materials and aluminum materials are used as raw materials, and the silver materials and aluminum materials are co-evaporated and deposited onto a shielding film substrate in a vacuum coating machine respectively to obtain an electromagnetic shielding film containing silver particles and aluminum particles; the silver materials and aluminum materials are separated by a partition plate and co-evaporated and deposited onto the shielding film substrate respectively, and the first rate of the silver materials in the co-evaporation deposition and the second rate of the aluminum materials in the co-evaporation deposition are controlled respectively, so that the proportion of silver particles and the proportion of aluminum particles in the electromagnetic shielding film meet the electromagnetic shielding requirements and the light transmittance requirements, so as to simultaneously have high light transmittance and strong shielding effect as required.

Description

Technical Field

[0001] This application relates to the technical fields of optical coating materials, electromagnetic shielding films, and vacuum coating technologies, and particularly relates to an ultra-thin transparent electromagnetic shielding film, a preparation method, and a device therefor. Background Art

[0002] Transparent electromagnetic shielding films have great application demands in many fields such as communication equipment, medical equipment, instruments, aerospace, and weaponry, such as in optoelectronic guided missiles, laser-guided missiles, and fighter cockpits, and have attracted wide attention. However, among current transparent shielding materials, it is difficult to simultaneously achieve high transmittance and strong shielding effect.

[0003] Based on this, a new technical solution for an electromagnetic shielding film that simultaneously has high transmittance and strong shielding effect is needed. Summary of the Invention

[0004] In view of this, embodiments of this specification provide an ultra-thin transparent electromagnetic shielding film, a preparation method, and a device therefor.

[0005] Embodiments of this specification provide the following technical solutions:

[0006] Embodiments of this specification provide a method for preparing an ultra-thin transparent electromagnetic shielding film, including: using silver material and aluminum material as raw materials, and respectively co-evaporating and depositing the silver material and the aluminum material onto a shielding film substrate in a vacuum coating machine to obtain an electromagnetic shielding film containing silver particles and aluminum particles; wherein, the silver material and the aluminum material are placed separately inside the vacuum coating machine with a partition, so that the silver material and the aluminum material are co-evaporated and deposited onto the shielding film substrate respectively under the separation of the partition.

[0007] During the co-evaporation and deposition process, according to the electromagnetic shielding requirements and light transmittance requirements of the electromagnetic shielding film, control the first rate of the silver material during co-evaporation and deposition, and control the second rate of the aluminum material during co-evaporation and deposition, so that the proportion of silver particle content and the proportion of aluminum particle content in the electromagnetic shielding film meet the electromagnetic shielding requirements and light transmittance requirements.

[0008] Embodiments of this specification also provide an ultra-thin transparent electromagnetic shielding film, which is an electromagnetic shielding film prepared by using the above method for preparing an ultra-thin transparent electromagnetic shielding film.

[0009] Embodiments of this specification also provide a device for preparing an ultra-thin transparent electromagnetic shielding film, including:

[0010] A partition, standing upright at the bottom of the vacuum coating machine;

[0011] Dual electron guns respectively located on both sides of the partition, and each electron gun serves as an evaporation source for evaporating silver material or an evaporation source for aluminum material;

[0012] A controller, connected to the electron gun, is configured to control a first rate of the silver material in co-evaporation deposition and a second rate of the aluminum material in co-evaporation deposition according to the electromagnetic shielding requirements and light transmittance requirements of the electromagnetic shielding film, so that the proportion of silver particles and the proportion of aluminum particles in the electromagnetic shielding film meet the electromagnetic shielding requirements and light transmittance requirements.

[0013] Compared with the prior art, the beneficial effects that can be achieved by at least one of the above technical solutions adopted in the embodiments of the present specification at least include:

[0014] In the present application, the silver material and the aluminum material are separated by a partition and co-evaporated onto the shielding film substrate respectively. The first rate of the silver material in co-evaporation deposition and the second rate of the aluminum material in co-evaporation deposition are controlled respectively, so that the proportion of silver particles in the electromagnetic shielding film meets the electromagnetic shielding requirements, and the proportion of aluminum particles meets the light transmittance requirements, so as to simultaneously have high light transmittance and strong shielding effect as needed. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments will be briefly introduced below. 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.

[0016] Figure 1 is a schematic structural diagram of the ultra-thin transparent electromagnetic shielding film of the present application;

[0017] Figure 2 is a schematic co-evaporation structure diagram of the present application;

[0018] Figure 3 is a spectral transmittance diagram of the ultra-thin Ag-Al film obtained in the embodiment of the present application;

[0019] Figure 4 is a SEM diagram of the ultra-thin Ag-Al film obtained in the embodiment of the present application;

[0020] Figure 5 is an EDS diagram of the ultra-thin Ag-Al film obtained in the embodiment of the present application.

[0021] Reference numerals: 1, first monitoring probe; 2, second monitoring probe; 3, third monitoring probe; 4, evaporation source of silver material; 5, evaporation source of aluminum material; 6, partition; 7, correction baffle; 8, shielding film substrate; 9, connection layer; 10, Ag-Al film. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The embodiments of the present application will be described in detail below with reference to the drawings.

[0023] The following describes the embodiments of the present application through specific specific examples. Those skilled in the art can easily understand the other advantages and effects of the present application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0024] It should be noted that the following describes various aspects of the embodiments within the scope of the appended claims. It should be obvious that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is illustrative only. Based on the present application, those skilled in the art should understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspects described herein can be used to implement the device and / or practice the method. Additionally, this device and / or this method can be implemented using other structures and / or functions in addition to one or more of the aspects described herein.

[0025] It also needs to be noted that the diagrams provided in the following embodiments only illustrate the basic concept of the present application in a schematic manner. The diagrams only show the components related to the present application, rather than being drawn according to the number, shape, and size of the components in actual implementation. The type, quantity, and proportion of each component in its actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0026] In addition, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the examples can be practiced without these specific details.

[0027] Through in-depth research and improvement exploration of coating materials and electromagnetic shielding films, the applicant found that: ultra-thin metal films have excellent optoelectronic properties and stability, and have the potential to become transparent electromagnetic shields. Among them, ultra-thin silver films (Ag) have become the most representative materials for transparent electromagnetic shielding due to their excellent transparency and good conductivity. However, according to the island growth mode (Volmer-Weber) thin film growth mechanism, it is difficult for Ag with a thickness below 20 nm to form a uniform and continuous Ag film, which in turn leads to poor electromagnetic shielding effect of the film layer; as the thickness of the Ag film increases, the Ag particles thicken, and the separated silver particles condense, diffuse, and connect to form a continuous and uniform silver film. At this time, the electromagnetic shielding effect is good, but the visible light transmittance decreases.

[0028] Based on this, the following will describe the technical solutions provided by each embodiment of the present application in conjunction with the accompanying drawings.

[0029] The embodiments of this specification propose a method for preparing an ultra-thin transparent electromagnetic shielding film, as Figure 1 and Figure 2 shown, including: using silver material and aluminum material as raw materials, and co-evaporating and depositing the silver material and aluminum material onto the shielding film substrate 8 in a vacuum coating machine respectively to obtain an electromagnetic shielding film containing silver particles and aluminum particles; the silver material and aluminum material are placed separately inside the vacuum coating machine with a partition 6, so that under the separation of the partition 6, the silver material and aluminum material co-evaporate and deposit onto the shielding film substrate 8 respectively.

[0030] In the co-evaporation deposition process, according to the electromagnetic shielding requirements and light transmittance requirements of the electromagnetic shielding film, control the first rate of the silver material in the co-evaporation deposition, and control the second rate of the aluminum material in the co-evaporation deposition, so that the proportion of silver particle content and the proportion of aluminum particle content in the electromagnetic shielding film meet the electromagnetic shielding requirements and light transmittance requirements. By using doping technology, doping a small amount of aluminum (Al) into the silver (Ag) film is beneficial to achieving a continuous and uniform film layer in the ultra-thin case of the silver (Ag) film, while taking into account high transmittance and good electromagnetic shielding effect.

[0031] In one embodiment, the first monitoring probe 1 monitors the first rate of the silver material in the co-evaporation deposition, and the second monitoring probe 2 monitors the second rate of the aluminum material in the co-evaporation deposition; wherein, the first monitoring probe 1 and the silver material are arranged on one side of the partition 6, the second monitoring probe 2 and the aluminum material are arranged on the other side of the partition 6, and the connection line between the first monitoring probe 1 and the evaporation source 5 of the aluminum material passes through the partition 6. Similarly, the connection line between the second monitoring probe 2 and the evaporation source 4 of the silver material passes through the partition 6, so that in the co-evaporation deposition, the first monitoring probe 1 does not collect the deposition parameters corresponding to the aluminum material, and the second monitoring probe 2 does not collect the deposition parameters corresponding to the silver material.

[0032] In one embodiment, the first rate monitored by the first monitoring probe 1 is 0.4 nm / s to 0.6 nm / s, and / or the second rate monitored by the second monitoring probe 2 is 0.02 nm / s to 0.05 nm / s. The first monitoring probe 1 and the second monitoring probe 2 can be in the same plane, and the evaporation source 4 of the silver material and the evaporation source 5 of the aluminum material can also be in the same plane. The distance between the first monitoring probe 1 and the plane where the evaporation source 4 of the silver material is located can be 60 to 90 cm.

[0033] In one embodiment, the method for preparing the electromagnetic shielding film further includes: monitoring the deposition rate and / or deposition thickness of the electromagnetic shielding film through the third monitoring probe 3.

[0034] In one embodiment, the deposition rate monitored by the third monitoring probe 3 is 0.42 nm / s to 0.44 nm / s, and can be preferably 0.43 nm / s; and / or the deposition thickness monitored by the third monitoring probe 3 is 7 nm to 10 nm. When the monitored deposition thickness exceeds 10 nm, the co-evaporation process is stopped. The third monitoring probe 3 and the shielding film substrate 8 can be in the same plane, and the evaporation source 4 of the silver material and the evaporation source 5 of the aluminum material can be in the same plane. The distance between the third monitoring probe 3 and the plane where the evaporation source 4 of the silver material is located can be 100 cm to 130 cm.

[0035] In one embodiment, silver particles are evaporated from the silver material during co-evaporation deposition, and aluminum particles are evaporated from the aluminum material during co-evaporation deposition; most of the silver particles and most of the aluminum particles are blocked by the correction baffle 7, so that a small part of the silver particles and a small part of the aluminum particles are deposited on the shielding layer substrate, so that the first rate is lower than the evaporation rate at the evaporation source 4 of the silver material, and the second rate is lower than the evaporation rate at the evaporation source 5 of the aluminum material.

[0036] In one embodiment, the correction baffle 7 is divided into flow guiding plates located on both sides of the plate surface where the partition plate 6 is located. The two flow guiding plates can be obliquely upward distributed in the direction towards the plate surface where the partition plate 6 is located, and a gap is formed between the two flow guiding plates. The formed gap is located above the partition plate 6, so that the silver particles and aluminum particles contacting the flow guiding plates flow towards the formed gap.

[0037] One side flow guiding plate is located on the side where the silver material is located, and the other side flow guiding plate is located on the side where the aluminum material is located; both flow guiding plates on both sides include a closed state and an open state; when the two flow guiding plates are in the open state, they are obliquely upward distributed in the direction towards the plate surface where the partition plate 6 is located; when the two flow guiding plates are in the closed state, they can both be horizontally distributed in the direction towards the plate surface where the partition plate 6 is located; when one side flow guiding plate is in the closed state, it can be located 40 cm to 60 cm directly above the evaporation source 4 of the silver material, and the width can be 10 to 20 cm; when the other side flow guiding plate is in the closed state, it can be located 40 cm to 60 cm directly above the evaporation source 5 of the aluminum material, and the width can be 10 to 20 cm.

[0038] Using precise monitoring technology, silver (Ag) films and aluminum (Al) films are prepared by electron beam evaporation. Their deposition rate is very fast (usually > 1.5 nm / s), and the total thickness of the ultra-thin films is only a few nanometers (usually less than 10 nm). Therefore, it is difficult to stably control the film thickness. The conventional correction baffle 7 is for improving the film uniformity. In this application, based on the method of designing an ultra-wide correction baffle 7, it is necessary to improve the film uniformity while blocking most of the film material particles, reducing the deposition rate on the sample surface, achieving the effect of a high evaporation rate at the evaporation source position but a small deposition rate on the actual sample surface, and achieving the purpose of effectively and stably controlling the thickness of the ultra-thin Ag-Al film 10. The ultra-wide correction baffle 7 is located 40 cm to 60 cm directly above the evaporation sources corresponding to the Al and Ag materials, with a width between 10 cm and 20 cm. The first monitoring probe 1 and the second monitoring probe 2 are located 20 cm - 30 cm above the correction baffle 7. The third monitoring probe 3 is basically in the same plane as the sample, 100 cm to 130 cm away from the evaporation source plane, and the specific dimensions are corrected and optimized according to the actual process.

[0039] In one embodiment, the method for preparing the electromagnetic shielding film further includes: after co-evaporation deposition, performing a vacuum annealing process on the electromagnetic shielding film. Using vacuum annealing technology. A reasonable vacuum annealing process is beneficial to make the surface of the Ag-Al film 10 more uniform, reduce the roughness (RMS), and reduce defects in the film coating process, such as incomplete crystallization, internal stress accumulation, and lattice defects.

[0040] In one embodiment, through experimental verification, the vacuum annealing process is as follows: the vacuum degree is above 2.0×10 -4 Pa, the heating rate is controlled within 20 °C / min, the highest temperature is 180 °C - 220 °C, the holding time is 3 - 8 min, and then it is naturally cooled to room temperature. When the vacuum degree is lower than 2.0X10 -4 Pa, there are more residual gases in the vacuum chamber. During high-temperature annealing, the metal film will react with the residual gases to form compounds, resulting in a decrease in the electromagnetic shielding effect.

[0041] In one embodiment, the shielding film substrate 8 uses any one of the following: substrate materials such as K9, JGS1, JGS2, JGS3, and sapphire. Two metal materials, silver (Ag) and aluminum (Al), are used, and the purity of both materials must be above 99.99%.

[0042] And / or, the co-evaporation deposition process uses electron beam co-evaporation, that is, the preparation method is vacuum electron beam co-evaporation evaporation technology.

[0043] And / or, before the co-evaporation process, the electron guns corresponding to the silver material and the aluminum material are fully pre-melted, and the deposition process starts after the error between the power of the electron gun and the power during deposition falls within the preset range.

[0044] And / or, before the co-evaporation process, the shielding film substrate 8 is cleaned and wiped with an alcohol-ether mixture.

[0045] And / or, before the co-evaporation process, the vacuum chamber is evacuated, and when the vacuum degree reaches the first vacuum degree, the shielding film substrate 8 is pretreated by ion cleaning. Among the ion source parameters used for ion cleaning, the voltage is 1200V and the current is 950mA, and the cleaning is carried out for 5 - 10 minutes.

[0046] In one embodiment, the method for preparing the electromagnetic shielding film further includes: before the co-evaporation deposition, a connection layer 9 is deposited on the shielding film substrate 8 as a connection between the shielding film substrate 8 and the electromagnetic shielding film.

[0047] In one embodiment, when the vacuum degree is the second vacuum degree, the connection layer 9 with a thickness of 10nm - 15nm is deposited on the shielding film substrate 8 at a preset rate, and / or the connection layer 9 is made of SiO2 or Al2O3. Using SiO2 or Al2O3 as the material of the connection layer 9 can effectively improve the adhesion between the metal film and the substrate and improve the mechanical firmness of the film layer.

[0048] In this application, two materials, silver Ag and aluminum Al, are deposited by co-precipitation evaporation and a direct vacuum annealing process is carried out after the coating is completed to obtain an ultra-thin Ag-Al transparent electromagnetic shielding film. The vacuum electron beam co-evaporation technology is used to simultaneously evaporate two materials, Ag and Al, and the proportion of the two materials in the Ag-Al film is controlled by the evaporation rate. Through process optimization and direct vacuum annealing treatment, an ultra-thin, uniform and continuous Ag-Al transparent electromagnetic shielding metal film is obtained.

[0049] This application can solve the problem that the current visible light transmittance is high but the electromagnetic shielding effect in the range of 20MHz - 5GHz is poor, or the electromagnetic shielding effect in the range of 20MHz - 5GHz is good but the visible light transmittance is low, and it cannot simultaneously achieve a high visible transmittance and a good electromagnetic shielding effect. In this application, two materials, Ag and Al, are deposited by co-precipitation evaporation and a direct vacuum annealing process is carried out after the coating is completed to prepare an ultra-thin Ag-Al transparent electromagnetic shielding film with a transmittance of more than 88% at a wavelength of 550nm and an average electromagnetic shielding of 27dB in the frequency band of 20MHz - 5GHz.

[0050] This embodiment of the specification also discloses an ultra-thin transparent electromagnetic shielding film, as Figure 1 and Figure 2 shown, which is an electromagnetic shielding film prepared by using the method for preparing an ultra-thin transparent electromagnetic shielding film according to any one of the above embodiments.

[0051] In one embodiment, the transmittance of the electromagnetic shielding film at a wavelength of 550nm is above 85%; and / or, the average electromagnetic shielding in the frequency band of 20MHz - 5GHz is 26dB - 35dB.

[0052] In one embodiment, the electromagnetic shielding film is a film with aluminum particles doped in silver particles, i.e., the Ag-Al film 10. The film layer composition is as follows: the content ratio of silver particles in the electromagnetic shielding film is 96 Atomic% to 92 Atomic%, and / or the content ratio of aluminum particles is 4 Atomic% to 8 Atomic%. Atomic% represents atomic percentage. Experimental verification shows that the doping ratio should be maintained at 96 Atomic% to 92 Atomic% for Ag and 4 Atomic% to 8 Atomic% for Al.

[0053] In one embodiment, the electromagnetic shielding film is connected to the shielding film substrate 8 through the connection layer 9. That is, the structure is as Figure 1 shown, consisting of a substrate, a connection layer 9, and an Ag-Al film 10. The substrate can be an electromagnetic film substrate.

[0054] The embodiment of this specification also provides a preparation device for an ultra-thin transparent electromagnetic shielding film, as Figure 1 and Figure 2 shown, including:

[0055] A partition 6, standing upright at the bottom of the vacuum coating machine.

[0056] Dual electron guns located on both sides of the partition 6 respectively, and each electron gun serves as an evaporation source 4 for evaporating silver material or an evaporation source 5 for evaporating aluminum material.

[0057] A controller, connected to the electron guns, for controlling the first rate of the silver material in the co-evaporation deposition and the second rate of the aluminum material in the co-evaporation deposition according to the electromagnetic shielding requirements and light transmittance requirements of the electromagnetic shielding film, so that the content ratios of silver particles and aluminum particles in the electromagnetic shielding film meet the electromagnetic shielding requirements and light transmittance requirements.

[0058] In one embodiment, the electromagnetic shielding film preparation device further includes: a first monitoring probe 1 and a second monitoring probe 2 connected to the controller; the first monitoring probe 1 monitors the first rate of the silver material in the co-evaporation deposition, and the second monitoring probe 2 monitors the second rate of the aluminum material in the co-evaporation deposition; wherein, the first monitoring probe 1 and the silver material are arranged on one side of the partition 6, the second monitoring probe 2 and the aluminum material are arranged on the other side of the partition 6, and the connection line between the first monitoring probe 1 and the evaporation source 5 of the aluminum material passes through the partition 6. Similarly, the connection line between the second monitoring probe 2 and the evaporation source 4 of the silver material passes through the partition 6, so that in the co-evaporation deposition, the first monitoring probe 1 does not collect the deposition parameters corresponding to the aluminum material, and the second monitoring probe 2 does not collect the deposition parameters corresponding to the silver material.

[0059] In one embodiment, the first rate monitored by the first monitoring probe 1 is 0.4 nm / s to 0.6 nm / s, and / or the second rate monitored by the second monitoring probe 2 is 0.02 nm / s to 0.05 nm / s.

[0060] In one embodiment, the electromagnetic shielding film preparation device further includes: a third monitoring probe 3 connected to the controller, and the third monitoring probe 3 monitors the deposition rate and / or deposition thickness of the electromagnetic shielding film.

[0061] In one embodiment, the deposition rate monitored by the third monitoring probe 3 is 0.42 nm / s to 0.44 nm / s; and / or the deposition thickness monitored by the third monitoring probe 3 is 7 nm to 10 nm. When the monitored deposition thickness exceeds 10 nm, the co-evaporation process is stopped.

[0062] In one embodiment, the electromagnetic shielding film preparation device further includes: a correction baffle 7; silver material evaporates to form silver particles during co-evaporation deposition, and aluminum material evaporates to form aluminum particles during co-evaporation deposition; the correction baffle 7 blocks most of the silver particles and most of the aluminum particles, so that a small part of the silver particles and a small part of the aluminum particles are deposited on the shielding layer substrate, so that the first rate is lower than the evaporation rate at the evaporation source 4 of the silver material, and the second rate is lower than the evaporation rate at the evaporation source 5 of the aluminum material.

[0063] In one embodiment, the correction baffle 7 is divided into flow guiding plates located on both sides of the plate surface where the partition plate 6 is located. The two flow guiding plates can be obliquely upward distributed in the direction of the plate surface where the partition plate 6 is located, and a gap is formed between the two flow guiding plates. The formed gap is located above the partition plate 6, so that the silver particles and aluminum particles contacting the flow guiding plates flow toward the formed gap. The controller can be connected to the correction baffle to control the opening and closing of the correction baffle and the opening angle of the flow guiding plate.

[0064] In one embodiment, the vacuum coating machine includes a 1300-type vacuum coating machine.

[0065] The embodiments of this specification also provide a manufacturing method of an ultra-thin transparent electromagnetic shielding film, as Figure 1 and Figure 2 shown, a 1300-type vacuum coating machine is used, which is equipped with a double electron gun, an RF 17 cm radio frequency ion source, a three-group multi-probe quartz crystal monitoring system, and a cryopump + dry pump oil-free exhaust system.

[0066] Using the double electron gun co-evaporation technology, an Ag-Al transparent electromagnetic shielding film is prepared on a K9 substrate with a diameter of 30 mm and a thickness of 2 mm. The co-evaporation schematic is as Figure 2 shown.

[0067] Co-evaporation scheme allocation: Two groups of electron gun evaporation sources are used to evaporate Ag and Al respectively. The third monitoring probe 3 monitors the deposition rate and thickness of Ag-Al, the first monitoring probe 1 monitors the deposition rate and thickness of Ag, and the second monitoring probe 2 monitors the deposition rate and thickness of Al. The function of the isolation baffle is to prevent the influence of the Ag deposition rate on the second monitoring probe 2 and the influence of the Al deposition rate on the second monitoring probe 2.

[0068] The deposition rate is controlled by adjusting the power of the electron gun to ensure the deposition rate. The deposition rate of Ag is 0.4 nm / s to 0.6 nm / s, and the deposition rate of Al is 0.02 nm / s to 0.05 nm / s. The thickness of the Ag-Al film 10 is 7 nm to 10 nm, and the average transmittance at 550 nm is 85% to 91%; the electromagnetic shielding in the frequency band of 20 MHz to 5 GHz is on average 26 dB to 35 dB.

[0069] The specific preparation process flow is as follows:

[0070] I. Clean and wipe the K9 substrate with a mixture of alcohol and ether. The K9 substrate can be called the sample or the shielding film substrate 8.

[0071] II. Place the wiped sample on the sample rack of the coating machine and evacuate the vacuum chamber. When the vacuum degree reaches 3.0×10 -4 Pa, turn on the radio frequency ion source to perform ion cleaning pretreatment on the sample. The parameters of the radio frequency ion source are a voltage of 1200 V and a current of 950 mA, and clean for 5 - 10 minutes.

[0072] III. After cleaning, when the vacuum degree stabilizes at 2.0×10 -4 Pa, start thin film deposition. Deposit a SiO2 thin film with a thickness of 10 nm to 15 nm at a rate of 0.7 nm / s as the connection layer 9.

[0073] IV. Start the preparation of the ultra-thin Ag-Al film 10. At the same time, turn on the electron guns corresponding to the Ag material and the Al material, pre-melt the Ag and Al materials. After sufficient pre-melting, open the baffles of Ag and Al simultaneously for co-evaporation to prepare the Ag-Al thin film. By adjusting the power of the electron gun, the monitored rate of Ag, that is, the rate monitored by the first monitoring probe 1, is controlled at about 0.5 nm / s, and the monitored rate of Al, that is, the rate monitored by the second monitoring probe 2, is controlled at about 0.03 nm / s. At this time, the rate of Ag-Al, that is, the rate monitored by the third monitoring probe 3, is about 0.42 nm / s to 0.44 nm / s. When the thickness displayed by the third monitoring probe 3 reaches 8 nm, turn off the electron gun, baffle and other systems to stop film layer deposition.

[0074] V. After the film layer deposition is completed, continue to evacuate. When the vacuum degree reaches 2.0×10 -4Pa, start the vacuum annealing process.

[0075] 6. Control the heating rate at about 15 °C / min, heat up to 200 °C, hold for 5 minutes, then stop vacuum pumping and heating, start natural cooling, and take out the sample when it reaches room temperature.

[0076] 7. The transmittance of the Ag-Al film in the visible light range is measured by an ultraviolet-visible-near-infrared spectrophotometer as Figure 3 shown. The transmittance at 550 nm is about 88.4%, and the thickness of the film layer of the Ag-Al film 10 under this process is measured to be 8.7 nm. Figure 3 In it, Wavelentg represents wavelength and Transmittance represents transmittance.

[0077] 8. The surface morphology of the Ag-Al sample is measured by a scanning electron microscope (SEM) as Figure 4 shown. It can be seen from the figure that the particles on the film layer surface are uniform, flat, and have good uniformity.

[0078] 9. The surface results of the Ag-Al sample are measured by an energy dispersive spectrometer (EDS) as Figure 5 shown. The proportions of Ag and Al in the film layer of the Ag-Al film 10 are 95.36 Atomic% and 4.64 Atomic% respectively, and all Ag particles and Al particles are evenly distributed in the film layer of the Ag-Al film 10. Figure 5 In it, Element represents element.

[0079] 10. The average electromagnetic shielding of the Ag-Al film 10 in the frequency band of 20 MHz to 5 GHz is measured by an electromagnetic shielding tester to be 27 dB.

[0080] Therefore, the ultra-thin Ag-Al film 10 can meet the requirements of both high transmittance and strong electromagnetic shielding effect.

[0081] The materials and methods of this application can achieve a strong electromagnetic shielding effect while maintaining high visible transmittance. A film with both high transparency and good electromagnetic shielding performance and its preparation method can be widely applied to various transparent electromagnetic shielding windows.

[0082] In this specification, the same or similar parts between each embodiment can be referred to each other. Each embodiment focuses on the differences from other embodiments. In particular, for the embodiments described later, the description is relatively simple, and the relevant parts can be referred to the partial description of the foregoing embodiments.

[0083] As described above, it is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A method for preparing an ultra-thin transparent electromagnetic shielding film, characterized in that: include: Using silver material and aluminum material as raw materials, the silver material and the aluminum material are respectively subjected to co-evaporation deposition treatment on a shielding film substrate in a vacuum coating machine to obtain an electromagnetic shielding film containing silver particles and aluminum particles; wherein the silver material and the aluminum material are separated by a partition and placed inside the vacuum coating machine, so that the silver material and the aluminum material are respectively co-evaporated and deposited on the shielding film substrate under the separation of the partition; In the co-evaporation deposition process, according to the electromagnetic shielding requirements and light transmittance requirements of the electromagnetic shielding film, the first rate of the silver material in the co-evaporation deposition is controlled, and the second rate of the aluminum material in the co-evaporation deposition is controlled, so that the proportion of the silver particles and the proportion of the aluminum particles in the electromagnetic shielding film meet the electromagnetic shielding requirements and light transmittance requirements; The silver material is evaporated in co-evaporation deposition to form the silver particles, and the aluminum material is evaporated in co-evaporation deposition to form the aluminum particles; By shielding most of the silver particles and most of the aluminum particles with a correction baffle, a small portion of the silver particles and a small portion of the aluminum particles are deposited on the shielding film substrate, so that the first rate is lower than the evaporation rate at the evaporation source of the silver material, and the second rate is lower than the evaporation rate at the evaporation source of the aluminum material, so as to achieve accurate monitoring of silver-aluminum co-evaporation deposition; The correction baffle is divided into guide plates located on both sides of the plate surface where the partition is located. The guide plates on both sides can be distributed obliquely upward in the direction of the plate surface where the partition is located, and a gap is formed between the guide plates on both sides. The formed gap is located above the partition, so that the silver particles and the aluminum particles contacting the guide plates can flow into the formed gap.

2. The method for preparing an ultra-thin transparent electromagnetic shielding film according to claim 1, characterized in that: The first rate of the silver material in the co-evaporation deposition is monitored by a first monitoring probe, and the second rate of the aluminum material in the co-evaporation deposition is monitored by a second monitoring probe; wherein the first monitoring probe and the silver material are arranged on one side of the partition, the second monitoring probe and the aluminum material are arranged on the other side of the partition, and the connection line between the first monitoring probe and the evaporation source of the aluminum material passes through the partition, and similarly, the connection line between the second monitoring probe and the evaporation source of the silver material passes through the partition, so that in the co-evaporation deposition, the first monitoring probe does not collect the deposition parameters corresponding to the aluminum material, and the second monitoring probe does not collect the deposition parameters corresponding to the silver material.

3. The method for preparing an ultra-thin transparent electromagnetic shielding film according to claim 2, characterized in that: The first rate monitored by the first monitoring probe is 0.4 nm / s to 0.6 nm / s, and / or the second rate monitored by the second monitoring probe is 0.02 nm / s to 0.05 nm / s.

4. The method for preparing an ultra-thin transparent electromagnetic shielding film according to claim 1, characterized in that: The method for preparing the electromagnetic shielding film further comprises: monitoring the deposition rate and / or deposition thickness of the electromagnetic shielding film by means of a third monitoring probe.

5. The method for preparing an ultra-thin transparent electromagnetic shielding film according to claim 4, characterized in that: The deposition rate monitored by the third monitoring probe is 0.42nm / s~0.44nm / s; and / or the deposition thickness monitored by the third monitoring probe is 7nm~10nm, wherein when the monitored deposition thickness exceeds 10nm, the co-evaporation process is stopped.

6. The method for preparing an ultra-thin transparent electromagnetic shielding film according to claim 1, characterized in that: The method for preparing the electromagnetic shielding film further comprises: after the co-evaporation deposition, performing a vacuum annealing process on the electromagnetic shielding film.

7. The method for preparing an ultra-thin transparent electromagnetic shielding film according to claim 6, characterized in that: The vacuum annealing process is: vacuum degree is 2.0 10 -4 Pa, the heating rate is controlled within 20℃ / min, the maximum temperature is 180℃-220℃, the holding time is 3-8min, and then it is naturally cooled to room temperature.

8. The method for preparing an ultra-thin transparent electromagnetic shielding film according to claim 1, characterized in that: The shielding film substrate is any one of the following: K9, JGS1, JGS2, JGS3 and sapphire; and / or, the co-evaporation deposition process uses electron beam co-evaporation; And / or, before the co-evaporation process, the electron guns corresponding to the silver material and the aluminum material are fully pre-melted, and the deposition process is started when the error between the power of the electron gun and the power during deposition falls within a preset range; and / or, before the co-evaporation treatment, the shielding film substrate is cleaned and wiped with an alcohol-ether mixture; And / or, before the co-evaporation treatment, the vacuum chamber is evacuated, and when the vacuum degree reaches a first vacuum degree, the shielding film substrate is pre-treated by ion cleaning, and the ion source parameters used for ion cleaning are voltage of 1200V, current of 950mA, and cleaning for 5-10 minutes.

9. The method for preparing an ultra-thin transparent electromagnetic shielding film according to claim 1, characterized in that: The method for preparing the electromagnetic shielding film further comprises: before the co-evaporation deposition, depositing a connection layer on the shielding film substrate to serve as a connection between the shielding film substrate and the electromagnetic shielding film.

10. The method for preparing an ultra-thin transparent electromagnetic shielding film according to claim 9, characterized in that: When the vacuum degree reaches the second vacuum degree, a connection layer of 10 nm to 15 nm is deposited on the shielding film substrate at a preset rate, and / or the connection layer is made of SiO2 or Al2O3.

11. An ultra-thin transparent electromagnetic shielding film, characterized in that: An electromagnetic shielding film prepared by the method for preparing an ultra-thin transparent electromagnetic shielding film according to any one of claims 1 to 10; The electromagnetic shielding film is connected to the shielding film substrate via a connecting layer.

12. The ultra-thin transparent electromagnetic shielding film according to claim 11, characterized in that: The electromagnetic shielding film has a transmittance of more than 85% at a wavelength of 550nm; and / or an average electromagnetic shielding of 26dB to 35dB in the frequency band of 20MHz to 5GHz.

13. The ultra-thin transparent electromagnetic shielding film according to claim 11, characterized in that: The electromagnetic shielding film is a film in which aluminum particles are doped in silver particles. The content of silver particles in the electromagnetic shielding film accounts for 96Atomic% to 92Atomic%, and / or the content of aluminum particles accounts for 4Atomic% to 8Atomic%.

14. An ultra-thin transparent electromagnetic shielding film preparation device, characterized in that: include: A partition is erected at the bottom of the vacuum coating machine; Dual electron guns are respectively located on both sides of the partition, each electron gun correspondingly serving as an evaporation source for evaporating silver material or an evaporation source for evaporating aluminum material; A controller connected to the electron gun, for controlling a first rate of the silver material in the co-evaporation deposition and a second rate of the aluminum material in the co-evaporation deposition according to the electromagnetic shielding requirements and the transmittance requirements of the electromagnetic shielding film, so that the proportion of the silver particles and the proportion of the aluminum particles in the electromagnetic shielding film meet the electromagnetic shielding requirements and the transmittance requirements; The electromagnetic shielding film preparation device also includes: a correction baffle; The silver material is evaporated in co-evaporation deposition to form the silver particles, and the aluminum material is evaporated in co-evaporation deposition to form the aluminum particles; The correction baffle shields most of the silver particles and most of the aluminum particles, and allows a small portion of the silver particles and a small portion of the aluminum particles to be deposited on the shielding film substrate, so that a first rate is lower than an evaporation rate at an evaporation source of the silver material, and a second rate is lower than an evaporation rate at an evaporation source of the aluminum material; The correction baffle is divided into guide plates located on both sides of the plate surface where the partition is located. The guide plates on both sides can be distributed obliquely upward in the direction of the plate surface where the partition is located, and a gap is formed between the guide plates on both sides. The formed gap is located above the partition, so that the silver particles and the aluminum particles contacting the guide plates can flow into the formed gap.

15. The ultra-thin transparent electromagnetic shielding film preparation device according to claim 14, characterized in that: The electromagnetic shielding film preparation device also includes: a first monitoring probe and a second monitoring probe connected to the controller; The first monitoring probe monitors a first rate of the silver material in the co-evaporation deposition, and the second monitoring probe monitors a second rate of the aluminum material in the co-evaporation deposition; The first monitoring probe and the silver material are arranged on one side of the partition, and the second monitoring probe and the aluminum material are arranged on the other side of the partition, and the connection line between the first monitoring probe and the evaporation source of the aluminum material passes through the partition, and similarly, the connection line between the second monitoring probe and the evaporation source of the silver material passes through the partition, so that during co-evaporation deposition, the first monitoring probe does not collect deposition parameters corresponding to the aluminum material, and the second monitoring probe does not collect deposition parameters corresponding to the silver material.

16. The ultra-thin transparent electromagnetic shielding film preparation device according to claim 15, characterized in that: The first rate monitored by the first monitoring probe is 0.4 nm / s to 0.6 nm / s, and / or the second rate monitored by the second monitoring probe is 0.02 nm / s to 0.05 nm / s.

17. The ultra-thin transparent electromagnetic shielding film preparation device according to claim 14, characterized in that: The electromagnetic shielding film preparation device further comprises: a third monitoring probe connected to the controller, wherein the third monitoring probe monitors the deposition rate and / or deposition thickness of the electromagnetic shielding film.

18. The ultra-thin transparent electromagnetic shielding film preparation device according to claim 17, characterized in that: The deposition rate monitored by the third monitoring probe is 0.42nm / s~0.44nm / s; and / or the deposition thickness monitored by the third monitoring probe is 7nm~10nm, wherein when the monitored deposition thickness exceeds 10nm, the co-evaporation process is stopped.

19. The ultra-thin transparent electromagnetic shielding film preparation device according to claim 14, characterized in that: The vacuum coating machine includes a 1300 type vacuum coating machine.

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