High-light-transmittance electromagnetic shielding film

Abstract

The utility model discloses a high-light-transmittance electromagnetic shielding film which comprises a transparent base material layer, a first protection layer, a metal shielding layer, a high-refractive-index anti-reflection layer and a second protection layer which are sequentially arranged in a stacked mode. Wherein the refractive index of the anti-reflection layer with the high refractive index is larger than 1.68, and the thickness of the anti-reflection layer with the high refractive index is 2-30 nm. According to the high-transmittance electromagnetic shielding film, the high-refractive-index anti-reflection layer is arranged between the metal shielding layer and the second protection layer, on one hand, the environment resistance and the anti-reflection performance of the shielding film can be enhanced, and on the other hand, the transmittance of the film is improved by utilizing the optical matching principle, so that the relatively high transmittance is ensured while low square resistance is realized, and the electromagnetic shielding film has a good application prospect. The transmittance reaches 35% and is increased by 45-55% compared with that of the shielding film without the high-refractive-index anti-reflection layer, and the requirements of specific application scenes can be met.

Description

Technical Field

[0001] The present application relates to the technical field of electromagnetic shielding films, and in particular to a high-transmittance electromagnetic shielding film. Background Art

[0002] The shielding principle of electromagnetic shielding film (EMI film) is primarily based on the properties of conductive and magnetic materials. It achieves its shielding effect by reflecting, absorbing, and attenuating electromagnetic waves. First, the electromagnetic shielding film uses the metal film layer on its surface to reflect electromagnetic waves, achieving its shielding effect. Second, the electromagnetic shielding film further enhances its shielding effect by absorbing the energy of electromagnetic waves.

[0003] Currently, wireless charging modules for certain mobile phones and wearable devices require electromagnetic shielding films that maintain high transmittance while maintaining low square resistance. For example, wireless charging modules commonly used in Apple products require electromagnetic shielding films to meet the die-cutting and subsequent product processing requirements due to the recognition characteristics of the production line's optical sensors. This requires that the transmittance of the electromagnetic shielding film used, when the square resistance is required to be 1 ohm, must reach over 30% in the visible light range to meet the process requirements. However, due to the matching issues between the film layers, the electromagnetic shielding film structure in the existing technology has a relatively low transmittance when achieving low square resistance, which does not meet the process requirements of back-end applications. Utility Model Content

[0004] The purpose of this application is to provide a high-transmittance electromagnetic shielding film to solve the problem of matching between the film layers of the electromagnetic shielding film structure in the prior art, where the transmittance is relatively low when low square resistance is achieved, and the process requirements of the back-end application are not met.

[0005] To achieve the above objectives, the technical solution adopted in this application is:

[0006] Provided is a high-transmittance electromagnetic shielding film, comprising a transparent substrate layer, a first protective layer, a metal shielding layer, a high-refractive-index anti-reflection layer, and a second protective layer stacked in sequence;

[0007] Wherein, the refractive index of the high-refractive-index anti-reflection layer is greater than 1.68, and the thickness of the high-refractive-index anti-reflection layer is 2-30 nm.

[0008] In one or more embodiments, the high refractive index anti-reflection layer is a stacked combination of one or more of a zinc oxide aluminum layer, a titanium oxide layer, an aluminum oxide layer, a zinc oxide layer, and an indium tin oxide layer.

[0009] In one or more embodiments, the high refractive index anti-reflection layer is an organic coating.

[0010] In one or more embodiments, the transparent substrate layer is a PET layer, a PP layer, a PE layer, a PI layer or a PC layer, and the thickness of the transparent substrate layer is 4 to 50 μm.

[0011] In one or more embodiments, the first protective layer is a zinc aluminum oxide layer, a titanium oxide layer, a niobium oxide layer, an aluminum oxide layer or a silicon oxide layer, and the thickness of the first protective layer is 2 to 30 nm.

[0012] In one or more embodiments, the metal shielding layer is a gold layer, a silver layer, a copper layer, a titanium layer, an aluminum layer, a palladium layer, a platinum layer or an alloy layer, and the thickness of the metal shielding layer is 5 to 60 nm.

[0013] In one or more embodiments, the second protective layer is a nickel layer, a chromium layer, a titanium layer, a zirconium layer or an alloy layer, and the thickness of the second protective layer is 0.5-10 nm.

[0014] In one or more embodiments, a capping layer is further included, and the capping layer is arranged on a side of the second protective layer away from the high refractive index anti-reflection layer.

[0015] In one or more embodiments, the capping layer is a titanium oxide layer, a niobium pentoxide layer, a silicon dioxide layer or a zirconium oxide layer, and the thickness of the capping layer is 3 to 20 nm.

[0016] In one or more embodiments, the high-transmittance electromagnetic shielding film has a sheet resistance of less than 1.2 ohms, and an average transmittance of incident light of 380-780 nm is greater than 30%.

[0017] Different from the prior art, the present invention has the following advantages:

[0018] The high-transmittance electromagnetic shielding film of the present application is provided with a high-refractive-index anti-reflection layer between the metal shielding layer and the second protective layer. On the one hand, it can enhance the environmental resistance and anti-reflection performance of the shielding film. On the other hand, it utilizes the optical matching principle to improve the transmittance of the film, thereby achieving low square resistance while ensuring a high transmittance. The transmittance reaches 35%, which is 45-55% higher than that of the shielding film without a high-refractive-index anti-reflection layer, and can meet the needs of specific application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] To more clearly illustrate the embodiments of this application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some of the embodiments described in this application. For those of ordinary skill in the art, other drawings can be derived from these drawings without inventive effort.

[0020] Figure 1It is a structural schematic diagram of an embodiment of the high-transmittance electromagnetic shielding film of the present application.

[0021] As shown in the figure:

[0022] Transparent substrate layer 100;

[0023] a first protective layer 200;

[0024] Metal shielding layer 300;

[0025] High refractive index anti-reflection layer 400;

[0026] A second protective layer 500;

[0027] Capping layer 600 . DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of this application.

[0029] Currently, portable electronic devices generally use electromagnetic shielding film structures with magnetron sputtered nano-scale shielding layers on polymer substrates. Their lightweight and bendable properties can meet the electromagnetic shielding requirements of most electronic devices. However, when used in wireless charging module scenarios on certain specific mobile phones and wearable devices, the transmittance of the electromagnetic shielding film used cannot meet the process requirements of the product. For example, the electromagnetic shielding film used in wireless charging modules commonly used by Apple products, during the die-cutting process and subsequent product processing, due to the recognition characteristics of the optical sensors on the production line, if the electromagnetic shielding film used has a square resistance requirement of 1 ohm, its transmittance in the visible light must reach more than 20% to meet the process requirements. Conventional electromagnetic shielding film structures have relatively low transmittance when achieving low square resistance due to the matching problems between the film layers, and cannot meet the process requirements of back-end applications.

[0030] In order to solve the above problems, the applicant has developed a new type of high-transmittance electromagnetic shielding film. On the one hand, this electromagnetic shielding film can enhance the environmental resistance and anti-reflection performance of the shielding film. On the other hand, it can also use the optical matching principle to improve the transmittance of the film, thereby achieving low square resistance while ensuring high transmittance to meet the needs of specific application scenarios.

[0031] Specifically, see Figure 1 , Figure 1 It is a structural schematic diagram of an embodiment of the high-transmittance electromagnetic shielding film of the present application.

[0032] like Figure 1 As shown, the high-transmittance electromagnetic shielding film includes a transparent substrate layer, a first protective layer, a metal shielding layer, a high-refractive-index anti-reflection layer, and a second protective layer stacked in sequence.

[0033] In one embodiment, the transparent substrate layer may be made of materials such as polyester (PET), polypropylene (PP), polyethylene (PE), polyimide (PI), and polycarbonate (PC), and may have a thickness of 4 to 50 μm.

[0034] The first protective layer is used to block moisture from penetrating the bottom of the transparent substrate layer from affecting the shielding layer, thereby improving the film's environmental resistance. In one embodiment, the first protective layer can be made of a metal oxide such as zinc aluminum oxide, titanium oxide, niobium oxide, aluminum oxide, or silicon oxide, and its thickness can be 2 to 30 nm.

[0035] The metal shielding layer is used to achieve electromagnetic shielding performance of the film. In one embodiment, the metal shielding layer can be made of a metal element with good conductivity such as gold, silver, copper, titanium, aluminum, palladium, platinum, or an alloy of the above metals, and its thickness can be 5 to 60 nm.

[0036] The high-refractive-index anti-reflection layer has a refractive index greater than 1.68 and a thickness of 2 to 30 nm. Based on the principle of optical matching, this layer improves the transmittance of the film, enabling the shielding film to maintain high transmittance while maintaining low sheet resistance. Furthermore, the high-refractive-index anti-reflection layer can also block water vapor and protect the metal functional layer.

[0037] In one embodiment, the high refractive index anti-reflection layer may be made of a metal oxide material with a high refractive index, such as zinc aluminum oxide, titanium oxide, aluminum oxide, zinc oxide, or indium tin oxide.

[0038] In another embodiment, the high-refractive-index anti-reflection layer may also be an organic coating having a refractive index that meets the requirements, and both can achieve the effects of this embodiment. For example, the high-refractive-index anti-reflection layer may be an acrylic resin with high-refractive-index particles, such as Toyokomei TYZ70-RA01-CN, or other types of resins that meet the refractive index and thickness requirements, and both can achieve the effects of this embodiment.

[0039] Preferably, the high refractive index anti-reflection layer can be made of metal oxide. Since metal oxide is an electrolyte and its dielectric constant and refractive index are different from those of the metal shielding layer, when the metal shielding layer is electroplated with a metal oxide nanocoating, the original optical response will be changed, and the anti-reflection performance of the metal film will be improved, allowing more light to penetrate the metal layer without being strongly reflected, thereby further improving the transmittance of the film.

[0040] The second protective layer is used to prevent oxidation and corrosion of the metal shielding layer by water, oxygen, acid, alkali, etc. In one embodiment, the second protective layer can be made of nickel, chromium, titanium, zirconium or alloys thereof, and its thickness can be 0.5 to 10 nm.

[0041] In order to facilitate the laser cutting process of the shielding film and further improve the environmental resistance of the shielding film, a capping layer may be arranged on the side of the second protective layer away from the high refractive index anti-reflection layer.

[0042] In one embodiment, the capping layer may be made of titanium oxide, niobium pentoxide, silicon dioxide, zirconium oxide, or the like, and may have a thickness of 3 to 20 nm.

[0043] The high-transmittance electromagnetic shielding film based on the above-mentioned embodiments can significantly improve the transmittance of the shielding film while ensuring a relatively low square resistance, so that the electromagnetic shielding film can meet the process requirements of back-end applications in some application scenarios.

[0044] The beneficial effects of the technical solution of the present application are further elaborated in detail below with reference to specific embodiments.

[0045] Example 1:

[0046] An electromagnetic shielding film comprises a transparent substrate layer, a first protective layer, a metal shielding layer, a high refractive index anti-reflection layer, a second protective layer and a capping layer which are stacked in sequence.

[0047] Among them, the transparent substrate layer is a PET layer with a thickness of 20μm, the first protective layer is a 20nm thick zinc oxide aluminum layer, the metal shielding layer is a 25nm thick metal silver layer, the high refractive index anti-reflection layer is a 20nm thick zinc oxide aluminum layer, the second protective layer is a 1nm thick nickel-chromium alloy layer, and the capping layer is a 10nm thick niobium pentoxide layer.

[0048] Example 2:

[0049] An electromagnetic shielding film comprises a transparent substrate layer, a first protective layer, a metal shielding layer, a high refractive index anti-reflection layer, a second protective layer and a capping layer which are stacked in sequence.

[0050] Among them, the transparent substrate layer is a PET layer with a thickness of 20μm, the first protective layer is a 10nm thick silicon oxide layer, the metal shielding layer is a 25nm thick metal silver layer, the high refractive index anti-reflection layer is a 20nm thick zinc oxide aluminum layer, the second protective layer is a 1nm thick nickel-chromium alloy layer, and the capping layer is a 10nm thick niobium pentoxide layer.

[0051] Example 3:

[0052] An electromagnetic shielding film comprises a transparent substrate layer, a first protective layer, a metal shielding layer, a high refractive index anti-reflection layer, a second protective layer and a capping layer which are stacked in sequence.

[0053] Among them, the transparent substrate layer is a PP layer with a thickness of 50μm, the first protective layer is a 10nm thick titanium oxide layer, the metal shielding layer is a 40nm thick metal copper layer, the high refractive index anti-reflection layer is a 2nm thick titanium oxide layer, the second protective layer is a 10nm thick nickel layer, and the capping layer is a 3nm thick silicon dioxide layer.

[0054] Example 4:

[0055] An electromagnetic shielding film comprises a transparent substrate layer, a first protective layer, a metal shielding layer, a high refractive index anti-reflection layer, a second protective layer and a capping layer which are stacked in sequence.

[0056] Among them, the transparent substrate layer is a PE layer with a thickness of 10μm, the first protective layer is a 2nm thick niobium oxide layer, the metal shielding layer is a 10nm thick metal platinum layer, the high refractive index anti-reflection layer is a 30nm thick indium tin oxide layer, the second protective layer is a 0.5nm thick titanium layer, and the capping layer is a 20nm thick titanium oxide layer.

[0057] Example 5:

[0058] An electromagnetic shielding film comprises a transparent substrate layer, a first protective layer, a metal shielding layer, a high refractive index anti-reflection layer, a second protective layer and a capping layer which are stacked in sequence.

[0059] Among them, the transparent substrate layer is a PI layer with a thickness of 30μm, the first protective layer is a 3nm thick zinc oxide aluminum layer, the metal shielding layer is a 60nm thick metal titanium layer, the high refractive index anti-reflection layer is a 15nm thick zinc oxide layer, the second protective layer is a 5nm thick zirconium layer, and the capping layer is a 10nm thick niobium pentoxide layer.

[0060] Example 6:

[0061] An electromagnetic shielding film comprises a transparent substrate layer, a first protective layer, a metal shielding layer, a high refractive index anti-reflection layer, a second protective layer and a capping layer which are stacked in sequence.

[0062] Among them, the transparent substrate layer is a PET layer with a thickness of 4μm, the first protective layer is a 30nm thick aluminum oxide layer, the metal shielding layer is a 10nm thick metal silver layer, the high refractive index anti-reflection layer is a 15nm thick zinc oxide layer, the second protective layer is a 5nm thick nickel-titanium alloy layer, and the capping layer is a 10nm thick niobium pentoxide layer.

[0063] Example 7:

[0064] An electromagnetic shielding film comprises a transparent substrate layer, a first protective layer, a metal shielding layer, a high refractive index anti-reflection layer, a second protective layer and a capping layer which are stacked in sequence.

[0065] Among them, the transparent substrate layer is a PET layer with a thickness of 20μm, the first protective layer is a 20nm thick zinc oxide aluminum layer, the metal shielding layer is a 25nm thick metal silver layer, the high refractive index anti-reflection layer is a 20nm thick acrylic resin layer, model Toyokomei TYZ70-RA01-CN, the second protective layer is a 1nm thick nickel-chromium alloy layer, and the capping layer is a 10nm thick niobium pentoxide layer.

[0066] Comparative Example 1:

[0067] An electromagnetic shielding film comprises a transparent substrate layer, a first protective layer, a metal shielding layer, a second protective layer and a capping layer which are stacked in sequence.

[0068] Among them, the transparent substrate layer is a PET layer with a thickness of 20μm, the first protective layer is a 20nm thick zinc oxide aluminum layer, the metal shielding layer is a 25nm thick metal silver layer, the second protective layer is a 1nm thick nickel-chromium alloy layer, and the capping layer is a 10nm thick niobium pentoxide layer.

[0069] Comparative Example 2:

[0070] An electromagnetic shielding film comprises a transparent substrate layer, a first protective layer, a metal shielding layer, a second protective layer and a capping layer which are stacked in sequence.

[0071] Among them, the transparent substrate layer is a PET layer with a thickness of 20μm, the first protective layer is a 10nm thick silicon oxide layer, the metal shielding layer is a 25nm thick metal silver layer, the second protective layer is a 1nm thick nickel-chromium alloy layer, and the capping layer is a 10nm thick niobium pentoxide layer.

[0072] Effect example:

[0073] The square resistance of the electromagnetic shielding films of Examples 1 and 2 and Comparative Examples 1 and 2 was measured using a square resistance meter using a probe measurement method; the transmittance of the electromagnetic shielding films of Examples 1 and 2 and Comparative Examples 1 and 2 for visible light of 380 to 780 nm was measured using a transmittance detector to obtain the data in the following table.

[0074] Membrane structure Square resistance Transmittance (380nm-780nm) Example 1 1Ω / □ 35％ Example 2 1Ω / □ 31％ Comparative Example 1 1Ω / □ 24％ Comparative Example 2 1Ω / □ 20％

[0075] Based on the data in the above table, it can be seen that the sheet resistance of Examples 1 and 2 and Comparative Examples 1 and 2 are both low, reaching 1Ω / □, but the transmittance of Comparative Examples 1 and 2 is much lower than that of Examples 1 and 2.

[0076] Specifically, comparing the data of Example 1 and Comparative Example 1, Example 1 adds a 20nm thick zinc oxide aluminum layer as a high refractive index anti-reflection layer on the basis of Comparative Example 1. After adding the high refractive index anti-reflection layer, the square resistance of the shielding film remains at a low value. At the same time, the transmittance of visible light of 380~780nm in Example 1 increases by 45.8% compared with Comparative Example 1, and the transmittance reaches 35%.

[0077] Furthermore, comparing the data of Example 2 and Comparative Example 2, Example 2 adds a 20nm thick zinc oxide aluminum layer as a high refractive index anti-reflection layer on the basis of Comparative Example 2. After adding the high refractive index anti-reflection layer, the square resistance of the shielding film remains at a low value. At the same time, the transmittance of visible light of 380~780nm in Example 2 increases by 55% compared with Comparative Example 2, and the transmittance reaches 31%.

[0078] This shows that the zinc oxide aluminum layer effectively improves the transmittance of the shielding film. The reason is that the newly added zinc oxide aluminum layer cooperates with other layers to improve the transmittance of the film based on the principle of optical matching. At the same time, the zinc oxide aluminum layer is an electrolyte, and its dielectric constant and refractive index are different from those of the metal shielding layer. The addition of the zinc oxide aluminum layer changes the original optical response and improves the anti-reflection performance of the metal film, allowing more light to penetrate the metal layer without being strongly reflected, thereby further improving the transmittance of the film.

[0079] For those skilled in the art, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0080] The foregoing descriptions of specific exemplary embodiments of the present application are for purposes of illustration and description. These descriptions are not intended to limit the present application to the precise forms disclosed, and it is apparent that many variations and modifications are possible in light of the foregoing teachings. The exemplary embodiments are selected and described for the purpose of explaining the specific principles of the present application and their practical application, thereby enabling those skilled in the art to realize and utilize the various exemplary embodiments of the present application and various options and modifications. The scope of the present application is intended to be defined by the claims and their equivalents.

Claims

1. A high-transmittance electromagnetic shielding film, characterized in that: It comprises a transparent substrate layer, a first protective layer, a metal shielding layer, a high refractive index anti-reflection layer and a second protective layer which are stacked in sequence; Wherein, the refractive index of the high-refractive-index anti-reflection layer is greater than 1.68, and the thickness of the high-refractive-index anti-reflection layer is 2-30 nm.

2. The high-transmittance electromagnetic shielding film according to claim 1, wherein The high refractive index anti-reflection layer is a stacked combination of one or more of a zinc oxide aluminum layer, a titanium oxide layer, an aluminum oxide layer, a zinc oxide layer and an indium tin oxide layer.

3. The high-transmittance electromagnetic shielding film according to claim 2, characterized in that: The high refractive index anti-reflection layer is an organic coating.

4. The high-transmittance electromagnetic shielding film according to claim 1, wherein The transparent substrate layer is a PET layer, a PP layer, a PE layer, a PI layer or a PC layer, and the thickness of the transparent substrate layer is 4 to 50 μm.

5. The high-transmittance electromagnetic shielding film according to claim 1, wherein The first protective layer is a zinc oxide aluminum layer, a titanium oxide layer, a niobium oxide layer, an aluminum oxide layer or a silicon oxide layer, and the thickness of the first protective layer is 2 to 30 nm.

6. The high-transmittance electromagnetic shielding film according to claim 1, wherein The metal shielding layer is a gold layer, a silver layer, a copper layer, a titanium layer, an aluminum layer, a palladium layer, a platinum layer or an alloy layer, and the thickness of the metal shielding layer is 5 to 60 nm.

7. The high-transmittance electromagnetic shielding film according to claim 1, wherein The second protective layer is a nickel layer, a chromium layer, a titanium layer, a zirconium layer or an alloy layer, and the thickness of the second protective layer is 0.5-10 nm.

8. The high-transmittance electromagnetic shielding film according to claim 1, wherein It also includes a capping layer, which is arranged on a side of the second protective layer away from the high refractive index anti-reflection layer.

9. The high-transmittance electromagnetic shielding film according to claim 8, characterized in that: The capping layer is a titanium oxide layer, a niobium pentoxide layer, a silicon dioxide layer or a zirconium oxide layer, and the thickness of the capping layer is 3 to 20 nm.

10. The high-transmittance electromagnetic shielding film according to any one of claims 1 to 9, characterized in that: The high-transmittance electromagnetic shielding film has a square resistance of less than 1.2 ohms and an average transmittance of more than 30% for incident light of 380 to 780 nm.

Images