Electromagnetic shielding film and circuit board

Abstract

The present invention discloses an electromagnetic shielding film and a circuit board. The electromagnetic shielding film comprises: a first shielding layer, an interlayer and a second shielding layer which are stacked in sequence; the thickness of the first shielding layer, the thickness of the second shielding layer and the thickness of the interlayer satisfy: 0.05≤d3 / (d1+d2)≤6.5. The interlayer is provided to increase the flexibility of the electromagnetic shielding film, and the provision of two shielding layers further enhances the shielding effect. The ratio of the thickness of the interlayer to the sum of the thickness of the two shielding layers is limited within a certain range, so that the thickness of the interlayer is within a suitable thickness range, which can have better stress, the device is resistant to bending, and the overall thickness of the electromagnetic shielding film is not too thick, which is conducive to the thinning of the device. At the same time, the thickness of the interlayer is relatively close to the sum of the thicknesses of the two shielding layers, which improves the stress transmission performance, makes the stress transmission more uniform, and avoids the breakage of the electromagnetic shielding film.

Description

Technical Field

[0001] The present invention relates to the field of electromagnetic shielding technology, and in particular to an electromagnetic shielding film and a circuit board. Background Art

[0002] With the development of miniaturization of communication equipment, there are higher and higher requirements for the miniaturization of integrated circuit boards. However, the further miniaturization of integrated circuit boards has also developed to a certain limit, so the miniaturization of communication equipment has also been restricted. In order to achieve further miniaturization of communication equipment, foldable mobile phones came into being. In order for foldable mobile phones to operate normally and avoid electromagnetic interference from the outside world and itself, it is necessary to apply a shielding film on the surface of the foldable mobile phone. However, the shielding film in the prior art is attached to a hard board and is not suitable for folding mobile phones or soft boards. Folding circuit boards or soft boards require long-term and high-frequency folding or opening and closing, and existing shielding films are difficult to meet such high requirements. Existing shielding films often cause the internal circuits of the circuit board or soft board to break after high-frequency bending, which in turn causes the circuit board or soft board to lose power, and the shielding effectiveness of the electromagnetic shielding film is also greatly reduced. Summary of the invention

[0003] The present invention provides an electromagnetic shielding film and a circuit board, so that the electromagnetic shielding film itself and the circuit board or flexible board containing the electromagnetic shielding film have better bending resistance and breakage resistance.

[0004] According to one aspect of the present invention, there is provided an electromagnetic shielding film, comprising: a first shielding layer, an interlayer, and a second shielding layer stacked in sequence;

[0005] The thickness of the first shielding layer, the thickness of the second shielding layer and the thickness of the interlayer satisfy:

[0006] 0.05≤d3 / (d1+d2)≤6.5; wherein d1 is the thickness of the first shielding layer, d2 is the thickness of the second shielding layer, and d3 is the thickness of the interlayer.

[0007] Optionally, the thickness of the first shielding layer, the thickness of the second shielding layer and the thickness of the interlayer also satisfy:

[0008] 0≤|d2-d1| / d3≤16.

[0009] Optionally, the material of the interlayer is non-metal.

[0010] Optionally, the thickness of the interlayer satisfies 0.25 μm≤d3≤5.8 μm.

[0011] Optionally, the electromagnetic shielding film further includes a base layer, and the base layer is arranged on a side of the first shielding layer away from the interlayer.

[0012] Optionally, the thickness of the base layer satisfies:

[0013] 2μm≤d4≤8μm; wherein d4 is the thickness of the base layer.

[0014] Optionally, the electromagnetic shielding film further includes an adhesive layer, and the adhesive layer is arranged on a side of the second shielding layer away from the interlayer.

[0015] Optionally, the thickness of the bonding layer and the thickness of the base layer satisfy:

[0016] 0.3≤d4 / d5≤4.5; wherein d5 is the thickness of the bonding layer.

[0017] Optionally, the thickness of the first shielding layer, the thickness of the second shielding layer, the thickness of the interlayer, the thickness of the base layer and the thickness of the bonding layer satisfy:

[0018] 0.1≤|(|d5-d2|) / (|d3-d2|)-(|d4-d1|) / (|d3-d1|)|≤83; d5 is the thickness of the adhesive layer.

[0019] Optionally, a surface of the second shielding layer away from the base layer has a protrusion.

[0020] Optionally, the bonding layer does not contain conductive particles.

[0021] Optionally, a surface of the second shielding layer away from the base layer is a flat surface, and the bonding layer contains conductive particles.

[0022] According to another aspect of the present invention, there is provided a circuit board comprising the electromagnetic shielding film described above.

[0023] The technical solution of the embodiment of the present invention increases the flexibility of the electromagnetic shielding film by setting an interlayer, and setting two shielding layers further improves the shielding effect. The ratio of the thickness of the interlayer to the sum of the thicknesses of the two shielding layers is limited within a certain range, so that the interlayer and the two shielding layers have better adaptability, which can improve the electromagnetic shielding film itself and the circuit board or soft board containing the electromagnetic shielding film to have better bending resistance and break resistance; at the same time, the overall thickness of the electromagnetic shielding film is not too thick, which is conducive to the thinning of the circuit board. At the same time, the difference between the thickness of the interlayer and the sum of the thicknesses of the two shielding layers is within a suitable range, so that the electromagnetic shielding film itself and the circuit board or soft board containing the electromagnetic shielding film have better bending resistance and break resistance.

[0024] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0026] Figure 1 A schematic structural diagram of an electromagnetic shielding film provided in Embodiment 1 of the present invention;

[0027] Figure 2 A schematic diagram of an electromagnetic shielding structure provided in Embodiment 2 of the present invention;

[0028] Figure 3 A schematic diagram of the structure of a circuit board provided in Embodiment 2 of the present invention. DETAILED DESCRIPTION

[0029] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0030] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0031] Embodiment 1

[0032] Figure 1 This is a schematic diagram of the structure of an electromagnetic shielding film provided in Example 1 of the present invention, referring to Figure 1 The electromagnetic shielding film comprises: a first shielding layer 10, an interlayer 11 and a second shielding layer 12 which are stacked in sequence;

[0033] The thickness of the first shielding layer 10, the thickness of the second shielding layer 12 and the thickness of the interlayer 11 satisfy:

[0034] 0.05≤d3 / (d1+d2)≤6.5; wherein d1 is the thickness of the first shielding layer 10 , d2 is the thickness of the second shielding layer 12 , and d3 is the thickness of the interlayer 11 .

[0035] The first shielding layer 10 and the second shielding layer 12 are conductive. The material of the first shielding layer 10 and the second shielding layer 12 can be metal or alloy. In order to ensure that the first shielding layer 10 and the second shielding layer 12 have good conductivity, the first shielding layer 10 and the second shielding layer 12 are made of at least one material selected from aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver, and gold. The materials of the first shielding layer 10 and the second shielding layer 12 can be the same or different, which is not specifically limited here. Exemplarily, the first shielding layer 10 and the second shielding layer 12 can be made of metal materials such as metallic silver. The interlayer 11 can be conductive or not, which is not specifically limited in this embodiment. The interlayer 11 is provided on the electromagnetic shielding film to improve the flexibility of the electromagnetic shielding film, wherein the interlayer 11 can be sticky so that the second shielding layer 12 is attached to one side of the first shielding layer 10.

[0036] If the ratio of the thickness of the interlayer 11 to the sum of the thicknesses of the two shielding layers is small, the thickness of the interlayer 11 will be too small compared to the thickness of the two shielding layers. The thickness is too thin, so that the interlayer 11 cannot play a good toughening role in the two shielding layers, resulting in brittle fracture of the two shielding layers, and cannot greatly increase the flexibility of the electromagnetic shielding film itself and the circuit board or soft board containing the electromagnetic shielding film, so that the bending resistance and step resistance of the electromagnetic shielding film itself and the circuit board or soft board containing the electromagnetic shielding film are reduced. If the ratio of the thickness of the interlayer 11 to the sum of the thicknesses of the two shielding layers is too large, the thickness of the interlayer 11 will be too large compared to the sum of the thicknesses of the two shielding layers. The thickness of the interlayer 11 is too thick, resulting in the overall thickness of the electromagnetic shielding film being too large, which is not conducive to application on the circuit board. At the same time, the thickness of the interlayer 11 is too large, resulting in the two shielding layers being more likely to break, and ultimately the bending resistance and step resistance of the electromagnetic shielding film itself and the circuit board or soft board containing the electromagnetic shielding film are reduced. And under the premise that the overall thickness of the electromagnetic shielding film is constant, if the thickness of the interlayer 11 is too large, the thickness of the first shielding layer 10 and the second shielding layer 12 will inevitably decrease, resulting in poor shielding effect of the shielding layer. At the same time, 0.05≤d3 / (d1+d2)≤6.5, the range of the above relationship can be an interval consisting of any two values ​​of 0.1, 0.5, 0.8, 1, 1.5, 1.8, 2.0, 2.1, 2.5, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8, 4.0, 4.2, 4.4, 4.6, 4.8, 5.0, 6.0, 6.4.

[0037] The technical solution of the embodiment of the present invention increases the flexibility of the electromagnetic shielding film by setting the interlayer 11, and the electromagnetic shielding film with two shielding layers further improves the shielding effect compared with the electromagnetic shielding film with a single shielding layer. The ratio of the thickness of the interlayer 11 to the sum of the thickness of the two shielding layers is limited to a certain range, so that the thickness of the interlayer 11 is within a suitable thickness range, which not only prevents the overall thickness of the electromagnetic shielding film from being too thick, but also helps to make the circuit board or soft board thinner and lighter; at the same time, the bending resistance of the electromagnetic shielding film itself and the circuit board or soft board containing the electromagnetic shielding film is improved.

[0038] Continue to refer Figure 1 Optionally, the thickness of the first shielding layer 10, the thickness of the second shielding layer 12 and the thickness of the interlayer 11 also satisfy: 0≤|d2-d1| / d3≤16, and the range of the above relationship can be 1, 1.5, 1.8, 2.0, 2.1, 2.5, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8, 4.0, 4.2, 4.4, 4.6, 4.8, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0, 15.0 or an interval consisting of any two values.

[0039] Furthermore, by limiting the ratio of the thickness difference between the two shielding layers and the thickness of the interlayer 11, the thickness difference between the two shielding layers is within an appropriate thickness range. If the thickness difference between the first shielding layer 10 and the second shielding layer 12 is too small relative to the interlayer 11, the thickness of the first shielding layer 10 and the thickness of the second shielding layer 12 are similar, which will cause stress concentration in the inner layer of the electromagnetic shielding film, thereby reducing the bending resistance of the electromagnetic shielding film itself and the circuit board or flexible board containing the electromagnetic shielding film; if the thickness difference between the first shielding layer 10 and the second shielding layer 12 is too large relative to the interlayer 11, the thickness of the first shielding layer 10 and the thickness of the second shielding layer 12 are greatly different, and the thickness of the first shielding layer 10 is too thin, which will result in low shielding effectiveness of the electromagnetic shielding film, and the step difference resistance of the electromagnetic shielding film is also greatly reduced.

[0040] Continue to refer Figure 1 Optionally, the material of the interlayer 11 is non-metal, and the material of the interlayer 11 is at least one or two of polyurethane, polyester, alkyd resin, epoxy resin, acrylic resin, polyimide, polystyrene, polyvinyl acetate, polyethylene, polypropylene, polyamide, rubber, phenolic resin, urethane resin, alkyd resin, and ABF resin, so that the interlayer 11 has better flexibility. At least one side of the interlayer 11 can be a non-flat structure.

[0041] Continue to refer Figure 1 Optionally, the thickness of the interlayer 11 satisfies 0.25 μm≤d3≤5.8 μm.

[0042] The interlayer 11 is used to enhance the flexibility of the electromagnetic shielding film. If the thickness of the interlayer 11 is less than 0.25 μm, the thickness of the interlayer 11 is too thin, which will lead to poor toughness of the entire electromagnetic shielding film, and the electromagnetic shielding film is very easy to break and deform when bent. If the thickness of the interlayer 11 is greater than 5.8 μm, the thickness of the interlayer is too thick, resulting in the thickness of the electromagnetic shielding film being too thick, which is not conducive to the application of the electromagnetic shielding film on the circuit board; in addition, the bending resistance of the electromagnetic shielding film itself and the circuit board or soft board containing the electromagnetic shielding film is reduced. Among them, the thickness of the interlayer 11 can be selected from any one of 0.5, 0.8, 1.0, 2.0, 3.0, 4.0, 5.0 or any two numerical values. The thickness of the interlayer 11 is preferably 0.8-2 μm.

[0043] Continue to refer Figure 1 Optionally, the electromagnetic shielding film further includes a base layer 13 , and the base layer 13 is arranged on a side of the first shielding layer 10 away from the interlayer 11 .

[0044] The base layer 13 is used to protect, support and insulate the electromagnetic shielding film. At the same time, the thickness of the base layer will also affect the bending resistance and step resistance of the electromagnetic shielding film itself and the circuit board or soft board containing the electromagnetic shielding. The thickness of the base layer 13 satisfies: 2μm≤d4≤8μm; wherein d4 is the thickness of the base layer 13. If the thickness of the base layer 13 is less than 2μm, the thickness is too thin, and the protective effect on other film layers such as the first shielding layer is poor. If the thickness of the base layer 13 is greater than 8μm, the overall thickness of the electromagnetic shielding film will be larger, which is not conducive to the bending of the electromagnetic shielding film and the circuit board or soft board containing the electromagnetic shielding film, and is not conducive to practical application. Therefore, the thickness range of the base layer 13 is 2μm-8μm, taking into account good protection performance and lightness. Among them, the thickness of the base layer 13 can be selected from any one of 2, 3, 4, 5, 6, 7, 8 or any two numerical value groups. The base layer 13 is selected from at least one of vinyl acetate, polyester, polyethylene, polyamide, rubber, acrylate, phenolic, epoxy, polyimide, urethane, melamine, alkyd, ABF and other resins.

[0045] Continue to refer Figure 1 Optionally, the electromagnetic shielding film further includes a bonding layer 14 , and the bonding layer 14 is disposed on a side of the second shielding layer 12 away from the interlayer 11 .

[0046] The adhesive layer 14 is sticky and is used to attach the electromagnetic shielding film to the circuit board to electromagnetically shield the components on the circuit board, wherein the adhesive layer 14 may contain conductive particles or may not contain conductive particles. The adhesive layer 14 is selected from at least one of vinyl acetate, polyester, polyethylene, polyamide, rubber, acrylate, phenolic, epoxy, polyimide, urethane, melamine, alkyd, ABF and other resins. Optionally, the thickness of the adhesive layer 14 and the thickness of the base layer 13 satisfy: 0.3≤d4 / d5≤4.5; wherein d5 is the thickness of the adhesive layer 14.

[0047] The base layer 13 and the adhesive layer 14 are two film layers on opposite sides of the electromagnetic shielding film, and the thickness ratio of the two has an impact on the bending resistance of the electromagnetic shielding film or the circuit board or soft board containing the electromagnetic shielding film. If the ratio of the thickness of the base layer 13 to the thickness of the adhesive layer 14 is less than 0.3, the thickness of the adhesive layer 14 is relatively large, which will cause stress concentration in the first shielding layer 10 and the second shielding layer 12, thereby reducing the bending resistance of the electromagnetic shielding film and the circuit board or soft board containing the electromagnetic shielding film, and reducing the step resistance of the electromagnetic shielding film. If the thickness of the base layer 13 and the thickness of the adhesive layer 14 are greater than 4.5, it means that the thickness of the adhesive layer 14 is too thin and it is difficult to provide a stable adhesive force, so that the electromagnetic shielding film and the circuit board or soft board fall off, resulting in a reduction in the bending resistance of the circuit board or soft board containing the electromagnetic shielding film, and a reduction in the step resistance of the electromagnetic shielding film. Therefore, the ratio of the thickness of the base layer 13 to the thickness of the adhesive layer 14 is in the range of 0.3-4.5, so that the thickness difference between the base layer 13 and the adhesive layer 14 is small, and the base layer 13 and the adhesive layer 14 are relatively symmetrically arranged on the opposite sides of the electromagnetic shielding film, so that the electromagnetic shielding film and the circuit board or flexible board containing the electromagnetic shielding film are more resistant to bending. Among them, the ratio can be selected from any one of 0.3, 0.5, 0.8, 1, 2, 3, 4, 4.4 or an interval of any two numerical groups.

[0048] Continue to refer Figure 1 Optionally, the thickness of the first shielding layer 10, the thickness of the second shielding layer 12, the thickness of the interlayer 11, the thickness of the base layer 13 and the thickness of the bonding layer 14 satisfy:

[0049] 0.1≤|(|d5-d2|) / (|d3-d2|)-(|d4-d1|) / (|d3-d1|)|≤83.

[0050] If |(|d5-d2|) / (|d3-d2|)-(|d4-d1|) / (|d3-d1|)|<0.1, the overall thickness of the base layer 13, the first shielding layer 10 and the interlayer 11 is greater than the overall thickness of the interlayer 11, the second shielding layer 12 and the bonding layer 14, and the thickness difference is large; or, |(|d5-d2|) / (|d3-d2|)-(|d4-d1|) / (|d3-d1|)|>83, the overall thickness of the interlayer 11, the second shielding layer 12 and the bonding layer 14 is greater than the overall thickness of the base layer 13, the first shielding layer 10 and the interlayer 11, and the thickness difference is large. In either of the above situations, the thickness of one side of the electromagnetic shielding film will be greater than that of the other side, resulting in poor symmetry in the thickness of the film layer, uneven stress transfer, and easy breakage of the film layer. Therefore, by setting 0.1≤|(|d5-d2|) / (|d3-d2|)-(|d4-d1|) / (|d3-d1|)|≤83, the overall thickness of the base layer 13, the first shielding layer 10 and the interlayer 11 can be closer to the overall thickness of the interlayer 11, the second shielding layer 12 and the bonding layer 14, which is more conducive to stress transfer. Among them, the formula range is selected from any one of 1, 2, 3, 4, 5, 6, 7, 8, 15, 25, 35, 45, 55, 65, 75, 80 or any two numerical value groups. Among them, the difference between d3-d2 and d3-d1 is not equal to 0. It should be noted that the average thickness of the electromagnetic shielding film is 5-20 microns.

[0051] Continue to refer Figure 1 Optionally, the adhesive layer 14 on the side of the second shielding layer 12 away from the base layer 13 contains conductive particles, so that when the electromagnetic shielding film is pressed onto a circuit board or a flexible board, the second shielding layer 12 can be connected to the ground layer on the circuit board through the conductive particles on the adhesive layer 14 to conduct the charge.

[0052] Embodiment 2

[0053] Figure 2 A schematic diagram of an electromagnetic shielding structure provided in the second embodiment of the present invention, referring to Figure 2 , Test Case 1

[0054] An electromagnetic shielding film comprises a base layer, a first shielding layer, an interlayer, a second shielding layer and an adhesive layer which are stacked in sequence, the thickness of the first shielding layer, the thickness of the second shielding layer and the thickness of the interlayer satisfy: 0.05≤d3 / (d1+d2)≤6.5, the first shielding layer and the second shielding layer are made of copper, the overall average thickness of the electromagnetic shielding film is 11 microns, the thickness of the interlayer satisfies 0.25μm≤d3≤5.8μm, and the thickness of the base layer satisfies 2μm≤d4≤8μm.

[0055] Test Example 2

[0056] This test example is the same as the other conditions of the test example 1, except that the thickness of the first shielding layer, the thickness of the second shielding layer and the thickness of the interlayer also satisfy: 0≤|d2-d1| / d3≤16.

[0057] Test Example 3

[0058] This test example is the same as the other conditions of test example 1, except that the thickness of the adhesive layer and the thickness of the base layer satisfy: 0.3≤d4 / d5≤4.5.

[0059] Test Example 4

[0060] This test example is the same as the other conditions of test example 3, except that the thickness of the first shielding layer, the thickness of the second shielding layer, the thickness of the interlayer, the thickness of the base layer and the thickness of the bonding layer meet the following conditions:

[0061] 0.1≤|(|d5-d2|) / (|d3-d2|)-(|d4-d1|) / (|d3-d1|)|≤83; d5 is the thickness of the adhesive layer.

[0062] Test Example 5

[0063] An electromagnetic shielding film comprises a base layer, a first shielding layer and an adhesive layer which are stacked in sequence, wherein the thickness of the first shielding layer is the same as that of test example 1.

[0064] Test Example 6

[0065] This test example has the same other conditions as test example 1, except that d3 / (d1+d2)≥7.

[0066] Table 1 Comparison of shielding effectiveness and bending resistance of different electromagnetic shielding films

[0067]

[0068]

[0069] The test method for the bending resistance of the electromagnetic shielding film is as follows: the bending resistance is to attach two electromagnetic shielding films of the same model to be tested to the two surfaces of the bending plate (the bending plate contains circuits) and press them (pre-pressing time 10 seconds, molding time 180 seconds, molding pressure 120kg, pressing temperature 185°C); bake and cure after pressing (baking temperature 160°C, baking time 90min); the strip width is 1.5cm, the bending conditions are: R angle 0.8mm, speed 60 rpm, angle ±135 degrees, load 500g, when the resistance of the bending circuit changes by more than 10%, stop the test. The shielding effectiveness of the electromagnetic shielding film is tested in accordance with GB / T30142-2013.

[0070] It can be seen from the above table that the electromagnetic shielding film provided by the embodiment of the present invention has good electromagnetic shielding effectiveness, and the bending resistance of the electromagnetic shielding film itself or the circuit board or flexible board containing the electromagnetic shielding film is greatly improved.

[0071] refer to Figure 2 Optionally, the surface of the second shielding layer 12 away from the base layer 13 has a protrusion, the adhesive layer 14 does not contain conductive particles, and the adhesive layer 14 may not be conductive. When the electromagnetic shielding film is pressed onto the circuit board, the protrusion of the second shielding layer 12 pierces the adhesive layer 14 to electrically connect the second shielding layer 12 to the ground layer on the circuit board.

[0072] Another method of this embodiment is: Figure 3 A schematic diagram of a circuit board provided in the second embodiment of the present invention, referring to Figure 3 A circuit board includes a circuit board body 15 and the electromagnetic shielding film in any of the above embodiments, and the electromagnetic shielding film is arranged on the circuit board body 15. The beneficial effects of the circuit board are the same as those of the electromagnetic shielding film, which will not be repeated here.

[0073] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0074] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An electromagnetic shielding film, characterized in that: include: A first shielding layer, an interlayer, and a second shielding layer are stacked in sequence; The thickness of the first shielding layer, the thickness of the second shielding layer and the thickness of the interlayer satisfy: 0.05≤d3 / (d1+d2)≤6.5; wherein d1 is the thickness of the first shielding layer, d2 is the thickness of the second shielding layer, and d3 is the thickness of the interlayer.

2. The electromagnetic shielding film according to claim 1, characterized in that The thickness of the first shielding layer, the thickness of the second shielding layer and the thickness of the interlayer also satisfy: 0≤|d2-d1| / d3≤16.

3. The electromagnetic shielding film according to claim 1, characterized in that The material of the interlayer is non-metal.

4. The electromagnetic shielding film according to claim 1, characterized in that The thickness of the interlayer satisfies 0.25 μm≤d3≤5.8 μm.

5. The electromagnetic shielding film according to claim 1, characterized in that The electromagnetic shielding film further includes a base layer, and the base layer is disposed on a side of the first shielding layer away from the interlayer.

6. The electromagnetic shielding film according to claim 5, characterized in that The thickness of the base layer satisfies: 2μm≤d4≤8μm; wherein d4 is the thickness of the base layer.

7. The electromagnetic shielding film according to claim 5, characterized in that The electromagnetic shielding film further includes a bonding layer, and the bonding layer is disposed on a side of the second shielding layer away from the interlayer.

8. The electromagnetic shielding film according to claim 7, characterized in that The thickness of the bonding layer and the thickness of the base layer satisfy: 0.3≤d4 / d5≤4.5; wherein d5 is the thickness of the bonding layer.

9. The electromagnetic shielding film according to claim 7, characterized in that The thickness of the first shielding layer, the thickness of the second shielding layer, the thickness of the interlayer, the thickness of the base layer and the thickness of the bonding layer satisfy the following conditions: 0.1≤|(|d5-d2|) / (|d3-d2|)-(|d4-d1|) / (|d3-d1|)|≤83; d5 is the thickness of the adhesive layer.

10. The electromagnetic shielding film according to claim 7, characterized in that A surface of the second shielding layer away from the base layer has a protrusion.

11. The electromagnetic shielding film according to claim 10, characterized in that The adhesive layer does not contain conductive particles.

12. The electromagnetic shielding film according to claim 7, characterized in that The surface of the second shielding layer away from the base layer is a flat surface, and the bonding layer contains conductive particles.

13. A circuit board, characterized in that: The electromagnetic shielding film comprises the electromagnetic shielding film according to any one of claims 1 to 12.

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