Electromagnetic shielding film and circuit board

Abstract

The 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, the first shielding layer, the interlayer and the second shielding layer are stacked in sequence, the first surface of the interlayer is attached to the first shielding layer, and the second surface of the interlayer is attached to the second shielding layer. The first surface of the interlayer is attached to the first shielding layer, the second surface of the interlayer is attached to the second shielding layer, the dyne value of the first surface is 28-38 dyn / cm, and the dyne value of the second surface is 28-40 dyn / cm. According to the invention, the phenomenon that the electromagnetic shielding film is delaminated after being bent for multiple times can be effectively avoided.

Description

Technical Field

[0001] The present invention relates to the field of electronic 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 reached a certain limit, so the miniaturization of communication equipment is also limited. In order to achieve further miniaturization of communication equipment, flexible printed circuits (FPC) came into being.

[0003] In order to allow the FPC to operate normally and avoid electromagnetic interference from the outside world and itself, an electromagnetic shielding film needs to be applied to the surface of the FPC. However, the electromagnetic shielding film in the prior art is attached to a hard board and is not suitable for FPC. FPC requires high-frequency folding or opening and closing. The existing electromagnetic shielding film is difficult to meet such high requirements and is prone to breakage and damage of the internal circuits of the FPC board after multiple bending. In order to solve the above technical problems, a high-performance electromagnetic shielding film is developed to improve the bending resistance of the FPC, and the electromagnetic shielding film itself also has good bending resistance. Summary of the invention

[0004] The scheme of the present invention provides an electromagnetic shielding film and a circuit board. The electromagnetic shielding film can make the circuit board or flexible board containing the electromagnetic shielding film have higher bending resistance, and the electromagnetic shielding film itself also has higher bending performance.

[0005] The scheme of the present invention provides an electromagnetic shielding film, which includes a first shielding layer, an interlayer and a second shielding layer. The first shielding layer, the interlayer and the second shielding layer are stacked in sequence, the first surface of the interlayer is bonded to the first shielding layer, and the second surface of the interlayer is bonded to the second shielding layer. The dyne value of the first surface is 28-38dyn / cm, and the dyne value of the second surface is 28-40dyn / cm.

[0006] As an improvement of the above solution, the difference between the dyne value of the first surface and the dyne value of the second surface is less than or equal to 6 dyn / cm.

[0007] As an improvement of the above solution, in Fourier transform infrared spectroscopy, the ratio of the infrared absorption peak intensity of the hydroxyl group of the interlayer to the entire infrared absorption peak intensity of the interlayer is 5%-15%.

[0008] As an improvement of the above solution, the first surface and the second surface contain silicon-oxygen bonds.

[0009] As an improvement of the above scheme, in Fourier transform infrared spectroscopy, the silicon-oxygen bond is -1 The infrared absorption peak intensity at 3200-3600cm -1 The ratio of the infrared absorption peak intensities at is 1.0-1.6.

[0010] As an improvement of the above solution, the interlayer is non-metallic, and the non-metallic is made of at least one material selected from epoxy resin, polyester resin, polyurethane resin, acrylic resin, alkyd resin, polyamide resin, and polyimide resin.

[0011] As an improvement of the above solution, the first shielding layer is a structure of at least two layers, and / or the second shielding layer is a structure of at least two layers.

[0012] As an improvement of the above-mentioned scheme, the first shielding layer is made of at least one material selected from the group consisting of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver, and gold; and / or the second shielding layer is made of at least one material selected from the group consisting of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver, and gold.

[0013] As an improvement of the above solution, a protrusion is provided on a side of the second shielding layer away from the interlayer.

[0014] As an improvement of the above solution, the electromagnetic shielding film includes an adhesive layer; the adhesive layer is arranged on a side of the second shielding layer away from the interlayer.

[0015] As an improvement of the above solution, the electromagnetic shielding film includes a base layer; the base layer is arranged on a side of the first shielding layer away from the interlayer.

[0016] Correspondingly, another embodiment of the present invention provides a circuit board, comprising a circuit board body and the electromagnetic shielding film as described in any one of the above items; the electromagnetic shielding film is pressed together with the circuit board body.

[0017] Compared with the prior art, the electromagnetic shielding film and circuit board provided by the solution of the present invention improve the bending resistance of the circuit board or soft board containing the electromagnetic shielding film by setting an interlayer between the first shielding layer and the second shielding layer, and the electromagnetic shielding film itself also has good bending resistance. By setting the dyne value of the side of the interlayer that is bonded to the first shielding layer, that is, the first surface, to 28-38dyn / cm, and setting the dyne value of the side of the interlayer that is bonded to the second shielding layer, that is, the second surface, to 28-40dyn / cm, the bonding force between the layers of the electromagnetic shielding film is improved, which can effectively avoid the phenomenon of delamination between the layers after the electromagnetic shielding film is bent multiple times. In addition, by setting the first shielding layer and the second shielding layer, the shielding effectiveness is greatly improved compared to setting only one shielding layer, and the shielding effectiveness is still high after a high step difference, and the shielding effectiveness reaches more than 62DB. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic structural diagram of a first electromagnetic shielding film provided by an embodiment of the present invention;

[0019] Figure 2 is a schematic structural diagram of a second electromagnetic shielding film provided by an embodiment of the present invention;

[0020] Figure 3 is a schematic structural diagram of a third electromagnetic shielding film provided by an embodiment of the present invention;

[0021] Figure 4 is a schematic structural diagram of a fourth electromagnetic shielding film provided by an embodiment of the present invention;

[0022] Figure 5 It is a structural schematic diagram of a circuit board provided by one embodiment of the present invention.

[0023] Notes on the accompanying drawings: 1. First shielding layer; 2. Interlayer; 3. Second shielding layer; 4. Adhesive layer; 5. Base layer; 6. Circuit board body. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions 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. The purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] In the description of the present invention, the terms "first", "second", "third", etc. are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second", "third", etc. may explicitly or implicitly include one or more of the feature. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0026] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be a connection between the two elements. The terms "vertical", "horizontal", "left", "right", "upper", "lower" and similar expressions used herein are only for illustrative purposes, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] In the description of the present invention, it should be noted that, unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0028] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0029] See also Figure 1 , is a schematic structural diagram of an electromagnetic shielding film provided by one embodiment of the present invention.

[0030] The present invention provides an electromagnetic shielding film, which includes a first shielding layer 1, an interlayer 2 and a second shielding layer 3. The first shielding layer 1, the interlayer 2 and the second shielding layer 3 are stacked in sequence, the first surface of the interlayer 2 is bonded to the first shielding layer 1, and the second surface of the interlayer 2 is bonded to the second shielding layer 3. The dyne value of the first surface is 28-38dyn / cm, and the dyne value of the second surface is 28-40dyn / cm.

[0031] It can be understood that the dyne value, also known as surface tension, is a physical quantity that measures the wetting ability of a liquid on a solid surface. The embodiment of the present invention improves the adhesion between the layers of the electromagnetic shielding film by setting a suitable dyne value, which can effectively avoid delamination between the layers of the electromagnetic shielding film after the electromagnetic shielding film is bent multiple times. It can also better transfer stress, so that the circuit board or flexible board containing the electromagnetic shielding film has better bending resistance.

[0032] In the embodiment of the present invention, by setting the interlayer 2 between the first shielding layer 1 and the second shielding layer 3, the bending resistance of the electromagnetic shielding film and the bending resistance of the circuit board or soft board containing the electromagnetic shielding film are improved. By setting the dyne value of the side of the interlayer 2 that is in contact with the first shielding layer 1, that is, the first surface, to 28-38dyn / cm, and setting the dyne value of the side of the interlayer 2 that is in contact with the second shielding layer 3, that is, the second surface, to 28-40dyn / cm, the bonding force between the layers of the electromagnetic shielding film is improved, which can effectively avoid the phenomenon of delamination between the layers after the electromagnetic shielding film is bent multiple times, and is more conducive to the transmission of stress. In addition, by setting the first shielding layer 1 and the second shielding layer 3, the shielding effectiveness is greatly improved compared to setting only one shielding layer, and the shielding effectiveness is still high after a high step difference, and the shielding effectiveness reaches more than 62DB.

[0033] Specifically, the dyne value of the first surface can be 28 dyn / cm, 30 dyn / cm, 32 dyn / cm, 34 dyn / cm, 36 dyn / cm, 38 dyn / cm, or an interval consisting of any two values. Of course, the dyne value of the first surface is not limited to the specific values ​​listed above, and can be set according to actual use requirements, which will not be described in detail here.

[0034] Specifically, the dyne value of the second surface can be 28 dyn / cm, 30 dyn / cm, 32 dyn / cm, 34 dyn / cm, 36 dyn / cm, 38 dyn / cm, 40 dyn / cm, or an interval consisting of any two values. Of course, the dyne value of the second surface is not limited to the specific values ​​listed above, and can be set according to actual use requirements, which will not be described in detail here.

[0035] Preferably, the difference between the dyne value of the first surface and the dyne value of the second surface is less than or equal to 6dyn / cm, which can make the difference in bonding force between the first shielding layer 1 and the interlayer 2 and between the interlayer 2 and the second shielding layer 3 smaller, thereby ensuring that there will be no delamination between the layers after the electromagnetic shielding film is bent multiple times, which is beneficial to the transfer of stress. Specifically, the difference between the dyne value of the first surface and the dyne value of the second surface can be 0dyn / cm, 2dyn / cm, 4dyn / cm, and 6dyn / cm. Of course, the difference between the dyne value of the first surface and the dyne value of the second surface is not limited to the specific values ​​listed above, and it can be set according to actual use requirements, and no further elaboration is made here.

[0036] In an embodiment of the present invention, in order to further improve the bonding force between the layers of the electromagnetic shielding film and the bending resistance of the electromagnetic shielding film itself; at the same time, the circuit board or soft board containing the electromagnetic shielding film can also be improved to have better bending resistance. In the Fourier transform infrared spectrum, the infrared absorption peak intensity of the hydroxyl group of the interlayer 2 accounts for 5%-15% of the total infrared absorption peak intensity of the interlayer 2, that is, the intensity of the hydroxyl group of the interlayer 2 in the Fourier transform infrared spectrum accounts for 5%-15%. Specifically, the ratio can be 5%, 6%, 7%, 8%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15% or an interval consisting of any two values. Of course, the ratio is not limited to the specific values ​​listed above, and it can be set according to the actual use requirements, and no further details are given here.

[0037] In an embodiment of the present invention, in order to further improve the bonding force between the layers of the electromagnetic shielding film and the bending resistance of the electromagnetic shielding film itself; and also to improve the circuit board or flexible board containing the electromagnetic shielding film to have better bending resistance, the first surface and the second surface contain silicon oxygen bonds. Among them, the higher the proportion of the infrared absorption peak intensity of the silicon oxygen bond, the higher the content of the silicon oxygen bond, and the stronger the bonding force and bending resistance. Preferably, the silicon oxygen bonds in the interlayer are between 1000-1100cm -1 The infrared absorption peak intensity at 3200-3600cm -1The ratio between the infrared absorption peak intensities at is 1.0-1.6. Specifically, the ratio can be 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6 or an interval consisting of any two values. Of course, the ratio is not limited to the specific values ​​listed above, and it can be set according to the actual use requirements, and no further elaboration is made here. It should be noted that the hydroxyl group and the siloxy bond are from the resin in the silane coupling agent or in the interlayer 2. Exemplarily, the silane coupling agent can be KH550, KH560, KH570, KBM403 or other silane coupling agents, which can be set according to the actual use requirements, and no further elaboration is made here. The silane coupling agent is coated on the interlayer surface or mixed in the interlayer. In addition, in the present invention, the scanning range of the infrared spectrometer in the sample detection is 500cm -1 Up to 4000cm -1 .

[0038] In the embodiment of the present invention, there is no special limitation on the material used for the interlayer 2, but in order to further improve the interlayer bonding force of the electromagnetic shielding film and the bending resistance of the electromagnetic shielding film itself; at the same time, it can also improve the circuit board or flexible board containing the electromagnetic shielding film to have better bending resistance, the interlayer 2 is non-metallic, and the non-metallic is made of at least one material selected from epoxy resin, polyester resin, polyurethane resin, acrylic resin, alkyd resin, polyamide resin or polyimide resin.

[0039] In the embodiment of the present invention, in order to better improve the shielding effectiveness of the electromagnetic shielding film, the first shielding layer 1 and the second shielding layer 3 can be a one-layer structure or at least a two-layer structure respectively; wherein, in order to ensure that the first shielding layer 1 has good conductivity, the first shielding layer 1 is made of at least one material selected from aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver, and gold; in order to ensure that the second shielding layer 3 has good conductivity, the second shielding layer 3 is made of at least one material selected from aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver, and gold. In addition, according to the needs of actual production and application, the first shielding layer 1 and the second shielding layer 3 of the embodiment of the present invention can be respectively set to a grid shape, a foam shape, etc., or they can be solid. wherein, the average thickness of the first shielding layer 1 and the second shielding layer 3 are respectively 0.5 microns to 6 microns; the average thickness of the interlayer 2 is 0.2 microns to 8 microns. The overall average thickness of the electromagnetic shielding film is 3 microns to 25 microns.

[0040] like Figure 2 In order to further improve the shielding effectiveness of the electromagnetic shielding film, a protrusion is provided on the side of the second shielding layer 3 away from the interlayer 2, so that the protrusion pierces during the pressing process to achieve reliable grounding of the second shielding layer 3, thereby effectively conducting away the interference charges accumulated in the electromagnetic shielding film and achieving the shielding function. It should be noted that Figure 3The shape of the protrusion shown is merely exemplary, and the protrusion in the present invention is not limited to the shape shown in the figure. As long as the protrusion has piercing ability, it is within the protection scope of the present invention.

[0041] In the embodiments of the present invention, see Figure 3 , the electromagnetic shielding film also includes an adhesive layer 4; the adhesive layer 4 is arranged on the side of the second shielding layer 3 away from the interlayer 2. The adhesive layer 4 has an adhesive effect, which can improve the adhesion between the electromagnetic shielding film and the circuit board. The adhesive force can reach more than 7N / cm, so that the electromagnetic shielding film is close to the surface of the circuit board to avoid the phenomenon of delamination and explosion. Among them, the embodiment of the present invention does not specifically limit the material used for the adhesive layer 4, but from the perspective of further improving the bending resistance, the adhesive layer 4 is made of at least one material selected from polystyrene, vinyl acetate, polyester, polyethylene, polyamide, rubber, acrylic, phenolic, epoxy, polyimide, urethane, melamine, alkyd, and ABF resin.

[0042] In the embodiments of the present invention, see Figure 4 , the electromagnetic shielding film also includes a base layer 5; the base layer 5 is arranged on the side of the first shielding layer 1 away from the interlayer 2. The base layer 5 has the function of protection and support, which can prevent the first shielding layer 1 from being damaged and thus reduce the shielding effectiveness; at the same time, the base layer 5 can play a good supporting role for the first shielding layer 1, which is convenient for the preparation of the first shielding layer 1 and subsequent structures. Among them, the embodiment of the present invention does not specifically limit the material used for the base layer 5, but from the perspective of further improving the bending resistance, the base layer 5 is made of at least one material selected from polystyrene, vinyl acetate, polyester, polyethylene, polyamide, rubber, acrylic, phenolic, epoxy, polyimide, urethane, melamine, alkyd, and ABF resin.

[0043] Specifically, when the electromagnetic shielding film includes a base layer 5, a first shielding layer 1, an interlayer 2, a second shielding layer 3 and a bonding layer 4, the method for preparing the electromagnetic shielding film includes:

[0044] 1) preparing a base layer 5;

[0045] 2) forming a first shielding layer 1 on one surface of the base layer 5;

[0046] 3) forming an interlayer 2 on a surface of the first shielding layer 1 away from the base layer 5;

[0047] 4) forming a second shielding layer 3 on a surface of the interlayer 2 away from the first shielding layer 1;

[0048] 5) An adhesive layer 4 is formed on the surface of the second shielding layer 3 away from the interlayer 2 .

[0049] Test examples are given below, but these examples are provided only for a better understanding of the present invention and its advantages, and are not intended to limit the present invention.

[0050] Test Example 1: An electromagnetic shielding film, comprising a base layer, a first shielding layer, an interlayer, a second shielding layer and an adhesive layer stacked in sequence, the first surface of the interlayer being bonded to the first shielding layer, the second surface of the interlayer being bonded to the second shielding layer, the dyne value of the first surface being 26 dyn / cm, and the dyne value of the second surface being 26 dyn / cm.

[0051] Test Example 2: An electromagnetic shielding film, comprising a base layer, a first shielding layer, an interlayer, a second shielding layer and an adhesive layer stacked in sequence, the first surface of the interlayer being bonded to the first shielding layer, the second surface of the interlayer being bonded to the second shielding layer, the dyne value of the first surface being 28 dyn / cm, and the dyne value of the second surface being 26 dyn / cm.

[0052] Test Example 3: An electromagnetic shielding film, comprising a base layer, a first shielding layer, an interlayer, a second shielding layer and an adhesive layer stacked in sequence, the first surface of the interlayer being bonded to the first shielding layer, the second surface of the interlayer being bonded to the second shielding layer, the dyne value of the first surface being 26 dyn / cm, and the dyne value of the second surface being 28 dyn / cm.

[0053] Test Example 4: An electromagnetic shielding film, comprising a base layer, a first shielding layer, an interlayer, a second shielding layer and an adhesive layer stacked in sequence, the first surface of the interlayer being bonded to the first shielding layer, the second surface of the interlayer being bonded to the second shielding layer, the dyne value of the first surface being 28 dyn / cm, and the dyne value of the second surface being 28 dyn / cm.

[0054] Test Example 5: An electromagnetic shielding film, comprising a base layer, a first shielding layer, an interlayer, a second shielding layer and an adhesive layer stacked in sequence, the first surface of the interlayer being bonded to the first shielding layer, the second surface of the interlayer being bonded to the second shielding layer, the dyne value of the first surface being 30 dyn / cm, and the dyne value of the second surface being 36 dyn / cm.

[0055] Test Example 6: An electromagnetic shielding film, comprising a base layer, a first shielding layer, an interlayer, a second shielding layer and an adhesive layer stacked in sequence, the first surface of the interlayer being bonded to the first shielding layer, the second surface of the interlayer being bonded to the second shielding layer, the dyne value of the first surface being 38 dyn / cm, and the dyne value of the second surface being 40 dyn / cm.

[0056] Test Example 7: An electromagnetic shielding film, comprising a base layer, a first shielding layer, an interlayer, a second shielding layer and an adhesive layer stacked in sequence, the first surface of the interlayer being bonded to the first shielding layer, the second surface of the interlayer being bonded to the second shielding layer, the dyne value of the first surface being 38 dyn / cm, and the dyne value of the second surface being 46 dyn / cm.

[0057] Test Example 8: An electromagnetic shielding film, comprising a base layer, a first shielding layer, an interlayer, a second shielding layer and an adhesive layer stacked in sequence, the first surface of the interlayer being bonded to the first shielding layer, the second surface of the interlayer being bonded to the second shielding layer, the dyne value of the first surface being 46 dyn / cm, and the dyne value of the second surface being 40 dyn / cm.

[0058] For the electromagnetic shielding films of the above test examples 1-8, the average thickness of the base layer, the first shielding layer, the interlayer, the second shielding layer and the bonding layer are basically consistent with other conditions. The overall average thickness of the electromagnetic shielding film is 12 microns, the average thickness of the first shielding layer is 0.9 microns, the average thickness of the second shielding layer is 1.8 microns, and the average thickness of the interlayer is 2.4 microns. The above samples were subjected to MIT folding endurance test and shielding effectiveness test respectively, and the test results are shown in Table 1.

[0059] The steps of the MIT folding endurance test include: pressing two electromagnetic shielding films on a folding plate in a counter-pressing manner, the pressing conditions are 185°C, pre-pressing for 10s, molding time for 180s, and molding pressure of 120kg / cm 2 , the pressing temperature is 185℃, and the baking and curing are carried out after pressing. The baking temperature is 160℃, the baking time is 90min, the strip width is 1.5cm, the R angle is 0.8, the speed is 60 rpm, the angle is ±135°, and the load is 500g; when the bending starts, when the line resistance changes by more than 10%, the machine automatically stops the test and records the number of bending times and the failure resistance value; the shielding effectiveness is tested in accordance with GB / T30142-2013.

[0060] Table 1

[0061] MIT folding test / times Shielding effectiveness test greater than / DB Test Example 1 Approx. 7900 Greater than 62 Test Example 2 Approx. 7,800 Greater than 62 Test Example 3 Approx. 8,100 Greater than 62 Test Example 4 More than 11000 Greater than 62 Test Example 5 More than 13000 Greater than 62 Test Example 6 More than 12000 Greater than 62 Test Example 7 Approx. 8,400 Greater than 62 Test Case 8 Approx. 8,300 Greater than 62

[0062] It can be seen from Table 1 that when the dyne value of the first surface is 28-38dyn / cm and the dyne value of the second surface is 28-40dyn / cm, the electromagnetic shielding film can have good bending resistance, and there will be no delamination between the layers after the electromagnetic shielding film is bent multiple times, and it still has a high shielding effectiveness after a high step difference, and the shielding effectiveness reaches more than 62DB. In addition, the electromagnetic shielding film also has good chemical resistance, flux resistance and thermal shock resistance.

[0063] See also Figure 5 Another embodiment of the present invention further provides a circuit board, which includes a circuit board body 6 and an electromagnetic shielding film as described in any of the above embodiments; the electromagnetic shielding film is pressed against the circuit board body 6. The side of the adhesive layer 4 away from the second shielding layer 3 is electrically connected to the ground layer of the circuit board body 6.

[0064] Preferably, the circuit board body 6 is one of a flexible single-sided board, a flexible double-sided board, a flexible multi-layer board, and a rigid-flexible board.

[0065] In an embodiment of the present invention, the side of the adhesive layer 4 away from the second shielding layer 3 is electrically connected to the ground layer of the circuit board body 6, thereby realizing the introduction of interference charges in the electromagnetic shielding film into the ground, avoiding the accumulation of interference charges to form an interference source affecting the normal operation of the circuit board.

[0066] Compared with the prior art, the circuit board provided in the embodiment of the present invention improves the bending resistance of the circuit board or soft board containing the electromagnetic shielding film by setting the interlayer 2 between the first shielding layer 1 and the second shielding layer 3, and the electromagnetic shielding film itself also has good bending resistance. By setting the dyne value of the side of the interlayer 2 that is in contact with the first shielding layer 1, that is, the first surface, to 28-38dyn / cm, and setting the dyne value of the side of the interlayer 2 that is in contact with the second shielding layer 3, that is, the second surface, to 28-40dyn / cm, the bonding force between the layers of the electromagnetic shielding film is improved, which can effectively avoid the phenomenon of delamination between the layers after the electromagnetic shielding film is bent multiple times. In addition, by setting the first shielding layer 1 and the second shielding layer 3, the shielding effectiveness is greatly improved compared to setting only one shielding layer, and the shielding effectiveness is still high after a high step difference, and the shielding effectiveness reaches more than 62DB.

[0067] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. An electromagnetic shielding film, characterized in that: The electromagnetic shielding film includes a first shielding layer, an interlayer and a second shielding layer. The first shielding layer, the interlayer and the second shielding layer are stacked in sequence. The first surface of the interlayer is in contact with the first shielding layer, and the second surface of the interlayer is in contact with the second shielding layer. The dyne value of the first surface is 28-38dyn / cm, and the dyne value of the second surface is 28-40dyn / cm.

2. The electromagnetic shielding film according to claim 1, wherein A difference between the dyne value of the first surface and the dyne value of the second surface is less than or equal to 6 dyn / cm.

3. The electromagnetic shielding film according to claim 1, wherein In the Fourier transform infrared spectrum, the ratio of the infrared absorption peak intensity of the hydroxyl group of the interlayer to the entire infrared absorption peak intensity of the interlayer is 5%-15%.

4. The electromagnetic shielding film according to claim 1, wherein The first surface and the second surface contain silicon-oxygen bonds.

5. The electromagnetic shielding film according to claim 4, characterized in that In Fourier transform infrared spectroscopy, the silicon-oxygen bond is -1 The infrared absorption peak intensity at 3200-3600cm -1 The ratio between the infrared absorption peak intensities at is 1.0-1.

6.

6. The electromagnetic shielding film according to claim 1, wherein The interlayer is non-metallic, and the non-metallic is made of at least one material selected from epoxy resin, polyester resin, polyurethane resin, acrylic resin, alkyd resin, polyamide resin, and polyimide resin.

7. The electromagnetic shielding film according to claim 1, wherein The first shielding layer is a structure of at least two layers, and / or the second shielding layer is a structure of at least two layers.

8. The electromagnetic shielding film according to claim 1, wherein The first shielding layer is made of at least one material selected from the group consisting of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver, and gold; and / or the second shielding layer is made of at least one material selected from the group consisting of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver, and gold.

9. The electromagnetic shielding film according to claim 1, wherein A protrusion is provided on a side of the second shielding layer away from the interlayer.

10. The electromagnetic shielding film according to claim 1, wherein The electromagnetic shielding film comprises an adhesive layer; the adhesive layer is arranged on a side of the second shielding layer away from the interlayer.

11. The electromagnetic shielding film according to claim 9 or 10, characterized in that: The electromagnetic shielding film comprises a base layer; the base layer is arranged on a side of the first shielding layer away from the interlayer.

12. A circuit board, characterized in that: It comprises a circuit board body and an electromagnetic shielding film as described in any one of claims 1 to 11; the electromagnetic shielding film is pressed together with the circuit board body.

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