Electromagnetic shielding film and circuit board

Abstract

The present invention relates to the field of electronic technologies, and discloses an electromagnetic shielding film and a circuit board. Among them, the electromagnetic shielding film includes a carrier layer, an insulating layer and a shielding layer; the carrier layer is disposed on one surface of the insulating layer, and the shielding layer is disposed on the surface of the insulating layer away from the carrier layer; the roughness Rz of the surface of the carrier layer close to the insulating layer is 0.5 - 20 micrometers. The present invention can ensure that the carrier layer is not easily detached, so as to protect the insulating layer, and at the same time, the carrier layer can be stably peeled off under a certain applied force, so as to facilitate use.

Description

Technical Field

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

[0002] With the rapid development of the electronic industry, electronic products are further moving towards miniaturization, lightweight, and high-density assembly, which greatly promotes the development of flexible printed circuits, thereby realizing the integration of component devices and wire connections. Flexible printed circuits can be widely used in industries such as mobile phones, liquid crystal displays, communications, and aerospace.

[0003] Driven by the international market, functional flexible printed circuits dominate the flexible printed circuit market, and an important indicator for evaluating the performance of functional flexible printed circuits is electromagnetic shielding (Electromagnetic Interference Shielding, abbreviated as EMI Shielding). With the integration of functions of communication devices such as mobile phones, the internal components thereof have become extremely high-frequency and high-speed. For example: In addition to the original audio transmission function, the camera function has become an essential function for mobile phones, and WLAN (Wireless Local Area Networks), GPS (Global Positioning System), and Internet access functions have become popular. Coupled with the integration of future sensing components, the trend of components becoming extremely high-frequency and high-speed is even more inevitable. The electromagnetic interference inside and outside the components, signal attenuation during transmission, insertion loss, and jitter problems caused by high-frequency and high-speed driving are gradually becoming serious.

[0004] Currently, the commonly used electromagnetic shielding film for existing circuit boards includes a carrier layer, an insulating layer, and a shielding layer. During use, the electromagnetic shielding film needs to be hot-pressed with the circuit board at a high temperature. After the hot pressing is completed, the carrier layer is peeled off, so that the shielding layer is electrically connected to the ground layer of the circuit board, and then the interfering charges are introduced into the ground layer of the circuit board, thereby achieving shielding.

[0005] The inventor of the present invention found the following technical problems in the process of implementing the present invention: There are problems that the carrier layer of the existing electromagnetic shielding film cannot be peeled off or the carrier layer is easily peeled off. Summary of the Invention

[0006] Aiming at the above problems, the purpose of the present invention is to provide an electromagnetic shielding film and a circuit board, which can ensure that the carrier layer is not easily peeled off, so as to protect the insulating layer, and at the same time, the carrier layer can be stably peeled off under a certain applied force, so as to facilitate use.

[0007] To achieve the above purpose, an embodiment of the present invention provides an electromagnetic shielding film, including a carrier layer, an insulating layer, and a shielding layer;

[0008] The carrier layer is disposed on one side of the insulating layer, and the shielding layer is disposed on the side of the insulating layer away from the carrier layer.

[0009] The roughness Rz of the side of the carrier layer close to the insulating layer is 0.5 - 20 microns.

[0010] As an improvement to the above solution, the roughness Rz is 1.5 - 7.8 microns.

[0011] As an improvement to the above solution, the tensile force between the carrier layer and the insulating layer is 0.03 - 2.93 N / cm.

[0012] As an improvement to the above solution, the thickness of the carrier layer is 7 - 150 microns.

[0013] As an improvement to the above solution, the insulating layer is formed on one side of the carrier layer, and the roughness Rz of the side of the insulating layer close to the carrier layer is 0.9 - 18 microns.

[0014] As an improvement to the above solution, the electromagnetic shielding film further includes an adhesive film layer; the adhesive film layer is disposed on the side of the shielding layer away from the insulating layer.

[0015] As an improvement to the above solution, the adhesive film layer includes an adhesive layer containing conductive particles; or, the adhesive film layer includes an adhesive layer without conductive particles.

[0016] As an improvement to the above solution, conductive protrusions are provided on the side of the shielding layer close to the adhesive film layer.

[0017] As an improvement to the above solution, the ratio of the roughness Rz of the side of the carrier layer close to the insulating layer to the thickness of the insulating layer is 0.125 - 2.

[0018] To solve the same technical problem, another embodiment of the present invention further provides a circuit board, which includes a circuit board body and the electromagnetic shielding film according to any one of the above solutions; the electromagnetic shielding film is press-fitted with the circuit board body; the side of the shielding layer away from the insulating layer is electrically connected to the ground layer of the circuit board body.

[0019] Compared with the prior art, the electromagnetic shielding film and the circuit board provided by the embodiments of the present invention have at least one of the following beneficial effects:

[0020] Since the roughness Rz of the side of the carrier layer close to the insulating layer is 0.5 - 20 microns, it can ensure that the carrier layer is not easily detached while being able to stably peel off the carrier layer under a certain applied force, without making the carrier layer and the insulating layer adhere too closely. After laminating the electromagnetic shielding film onto the circuit board, the carrier layer can be stably peeled off under a certain applied force, thus facilitating use. Moreover, since the roughness Rz of the side of the carrier layer close to the insulating layer is 0.5 - 20 microns, compared with the carrier layer having a flat surface structure, when the electromagnetic shielding film is laminated onto the circuit board, the carrier layer is not likely to undergo a large horizontal movement during the lamination process. Therefore, it is not easy to have the problem that the overall electromagnetic shielding film is driven to move horizontally due to the horizontal movement of the carrier layer when laminating the electromagnetic shielding film onto the circuit board, and the electromagnetic shielding film can be laminated at the corresponding position on the circuit board. Brief Description of the Drawings

[0021] In order to more clearly illustrate the technical solutions of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0022] Figure 1 is a schematic structural diagram of the first electromagnetic shielding film provided by an embodiment of the present invention;

[0023] Figure 2 is a schematic structural diagram of the second electromagnetic shielding film provided by an embodiment of the present invention;

[0024] Figure 3 is a schematic structural diagram of the third electromagnetic shielding film provided by an embodiment of the present invention;

[0025] Figure 4 is a schematic structural diagram of the conductive protrusion provided by an embodiment of the present invention;

[0026] Figure 5 is a schematic structural diagram of the fourth electromagnetic shielding film provided by an embodiment of the present invention;

[0027] Figure 6 is a schematic structural diagram of the electromagnetic shielding film after being laminated with the circuit board body.

[0028] Wherein, 1. Carrier layer; 2. Insulating layer; 3. Shielding layer; 4. Adhesive film layer; 5. Protective film layer; 6. Circuit board body; 31. Conductive protrusion; 310. Conductive matrix part; 311. Conductive spike part. Detailed Embodiments

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0030] In the description of the specification and the claims, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the embodiments of the present invention, rather than indicating or implying that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the embodiments of the present invention.

[0031] In addition, the terms first, second, etc. in the specification and the claims are only used for the purpose of distinguishing the description of the same technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features, nor necessarily describing the order or time sequence. The terms can be interchanged under appropriate circumstances. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature.

[0032] See Figure 1 , an embodiment of the present invention provides an electromagnetic shielding film, which includes a carrier layer 1, an insulating layer 2, and a shielding layer 3; the carrier layer 1 is disposed on one surface of the insulating layer 2, and the shielding layer 3 is disposed on the surface of the insulating layer 2 away from the carrier layer 1; the roughness Rz of the surface of the carrier layer 1 close to the insulating layer 2 is 0.5-20 microns.

[0033] In an embodiment of the present invention, by making the roughness Rz of the surface of the carrier layer 1 close to the insulating layer 2 be 0.5 - 20 micrometers, it can ensure that the carrier layer 1 is not easily detached while being able to stably peel off the carrier layer 1 under the application of a certain force, without making the carrier layer 1 and the insulating layer 2 adhere too closely. After laminating the electromagnetic shielding film onto the circuit board, the carrier layer 1 can be stably peeled off under the application of a certain force, so as to facilitate use. Preferably, the roughness Rz of the surface of the carrier layer close to the insulating layer is 1.5 - 7.8 micrometers. Moreover, since the roughness Rz of the surface of the carrier layer 1 close to the insulating layer 2 is 0.5 - 20 micrometers, compared with the carrier layer 1 with a flat surface structure, during the lamination of the electromagnetic shielding film and the circuit board, the carrier layer 1 is not likely to have a large horizontal movement during the lamination process. Therefore, it is not easy to have the problem that the overall electromagnetic shielding film moves horizontally due to the horizontal movement of the carrier layer 1 when laminating the electromagnetic shielding film onto the circuit board, and the electromagnetic shielding film can be laminated at the corresponding position on the circuit board.

[0034] It can be understood that the roughness Rz is the sum of the average value of the five largest profile peak heights and the average value of the five largest profile valley depths within the sampling length.

[0035] Among them, the material of the carrier layer 1 can be PET (Polyethylene terephthalate, polyester resin). It can be understood that in order to ensure that the shielding layer 3 has good conductivity, the shielding layer 3 includes one or more of a metal shielding layer, a carbon nanotube shielding layer, a ferrite shielding layer, and a graphene shielding layer. Among them, the metal shielding layer includes a single-metal shielding layer and / or an alloy shielding layer; among them, the single-metal shielding layer is made of any one of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver, and gold, and the alloy shielding layer is made of any two or more of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver, and gold.

[0036] In this embodiment, the thickness of the carrier layer 1 is 7 - 150 micrometers. The carrier layer 1 can be used to protect the insulating layer 2 so that the insulating layer 2 is not damaged by external contact or collision, etc. Among them, when the thickness of the carrier layer 1 is 50 micrometers, it has better protection ability and can perfectly protect the insulating layer 2 from being damaged by external contact or collision, etc. In addition, the carrier layer 1 can be used as the base film for forming the insulating layer 2, that is: the insulating layer 2 can be formed on one side of the carrier layer 1.

[0037] In this embodiment, the roughness Sku of the surface of the carrier layer 1 close to the insulating layer 2 is 0.5 - 25 microns. When the roughness Sku of the surface of the carrier layer 1 close to the insulating layer 2 is 0.5 - 25 microns, it can ensure that the carrier layer 1 is not easily detached while being stably peeled off under a certain applied force. Among them, the roughness Sku is a parameter for judging the sharpness of the roughness shape. In addition, the test standard for the roughness Sku is ISO25178.

[0038] In this embodiment, the tensile force between the carrier layer 1 and the insulating layer 2 is 0.03 - 2.93. By setting the tensile force between the carrier layer 1 and the insulating layer 2 to 0.03 - 2.93 N / cm, the problem of reverse release (that is, after lamination, there is a problem that part of the carrier layer remains on the surface of the insulating layer) can be solved, and the carrier layer 1 can be stably peeled off after laminating the electromagnetic shielding film, thereby avoiding the presence of the residual carrier layer 1 on the insulating layer 2.

[0039] In this embodiment, before laminating the electromagnetic shielding film onto the circuit board, the tensile force between the carrier layer 1 and the insulating layer 2 is 0.1 - 2.93 N / cm. Setting the tensile force before lamination to 0.1 - 2.93 N / cm can prevent the detachment of the carrier layer 1 and play a role in protecting the insulating layer 2. After laminating the electromagnetic shielding film onto the circuit board, the tensile force between the carrier layer 1 and the insulating layer 2 is 0.03 - 2 N / cm. Setting the tensile force after lamination to 0.03 - 2 N / cm facilitates the stable peeling off of the carrier layer 1.

[0040] In this embodiment, the thickness of the insulating layer 2 is 5 - 8 microns, and the ratio of the roughness Rz of the surface of the carrier layer 1 close to the insulating layer 2 to the thickness of the insulating layer 2 is 0.125 - 2. During the process of forming the insulating layer 2 on the surface of the carrier layer 1 close to the insulating layer 2, when the ratio of the roughness Rz of the surface of the carrier layer 1 close to the insulating layer 2 to the thickness of the insulating layer 2 is 0.125 - 2, it is easy to make the roughness Rz of the surface of the insulating layer 2 far from the carrier layer 1 be 0.5 - 20 microns. It should be noted that the roughness of the surface of the insulating layer 2 can be formed by the roughness of the carrier layer 1 or can also be further processed by other means, which is not limited here.

[0041] Exemplarily, the roughness Rz of the surface of the insulating layer 2 close to the carrier layer 1 is 0.9 - 18 microns, and the roughness Sku of the surface of the insulating layer 2 close to the carrier layer 1 is 0.5 - 20 microns. This can improve the surface tension of the insulating layer. When printing ink on the insulating layer, the ink will not spread. Exemplarily, in application, when printing characters on the surface of the insulating layer, the characters can be clearly displayed.

[0042] In this embodiment, the side of the insulating layer 2 close to the shielding layer 3 is a rough surface, which can improve the bending resistance of the insulating layer 2, thereby improving the bending resistance of the electromagnetic shielding film. In addition, when the shielding layer 3 is formed on one side of the insulating layer 2, since the thickness of the shielding layer 3 is constant, the shielding layer 3 will rise and fall with the rough surface of the insulating layer 2, so that the side of the shielding layer 3 close to the film layer can also be a rough surface.

[0043] In this embodiment, the side of the insulating layer 2 close to the shielding layer 3 is a rough surface. The insulating layer 2 can effectively electrically isolate the shielding layer 3 from the outside, thereby ensuring the electromagnetic shielding effect of the shielding layer 3. Moreover, the side of the insulating layer 2 close to the shielding layer 3 is a rough surface, which can improve the bonding strength between the insulating layer 2 and the shielding layer 3 and prevent the insulating layer 2 and the shielding layer 3 from easily falling off.

[0044] Further, see Figure 2 The electromagnetic shielding film further comprises a film layer 4; the film layer 4 is arranged on the side of the shielding layer 3 away from the insulating layer 2; the side of the shielding layer 3 close to the film layer 4 is a rough surface. The electromagnetic shielding film is pressed against the circuit board body through the film layer 4; the rough surface of the shielding layer 3 pierces the film layer 4 and is electrically connected to the ground layer of the circuit board body.

[0045] The material used for the adhesive film layer 4 is selected from the following: modified epoxy resin, acrylic acid, modified rubber, and modified thermoplastic polyimide.

[0046] In the embodiment of the present invention, the side of the shielding layer 3 close to the adhesive film layer 4 is a rough surface. By making the side of the shielding layer 3 close to the adhesive film layer 4 a rough surface, the rough surface of the shielding layer 3 can be made to have piercing ability. Moreover, the rough surface of the shielding layer 3 can enhance the bonding force between the shielding layer 3 and the circuit board, so that the electromagnetic shielding film is not easy to be delaminated. Moreover, when the electromagnetic shielding film and the circuit board are pressed together, since the side of the shielding layer 3 close to the adhesive film layer 4 is a rough surface, the adhesive material constituting the adhesive film layer 4 is squeezed into the concave position of the rough surface of the shielding layer 3, increasing the amount of adhesive. On the one hand, it is not easy to cause the board to explode, avoiding the problem of high-temperature explosion of the existing electromagnetic shielding film due to insufficient adhesive capacity, thereby effectively ensuring the grounding of the electromagnetic shielding film, thereby extracting the interference charge; on the other hand, it can prevent the glue from overflowing to the edge of the circuit board during pressing, so that the circuit board after pressing the shielding film has a good appearance.

[0047] For example, refer to Figure 3 On one side of the shielding layer 3 close to the adhesive film layer 4, there are conductive protrusions 31, which can more effectively pierce the adhesive film layer 4, thereby further ensuring the electrical connection between the electromagnetic shielding film and the ground layer of the circuit board. It should be noted that the materials of the conductive protrusions 31 and the shielding layer 3 can be the same or different, and the present invention does not make specific limitations here.

[0048] In the above embodiment, refer to Figure 4 The conductive protrusion 31 includes a conductive base portion 310 and at least one conductive spike portion 311; the conductive base portion 310 extends outward from the side of the shielding layer 3 close to the adhesive film layer 4, and at least one of the conductive spike portions 311 extends outward from the surface of the conductive base portion 310. Among them, the conductive spike portions 311 extending from the surface of the conductive base portion 310 can more effectively pierce the adhesive film layer 4, so that the shielding layer 3 can be better electrically connected to the ground layer of the circuit board.

[0049] Specifically, the protruding height of the conductive spike portion 311 is 1-10 microns. This can more effectively pierce the adhesive film layer 4, thereby further ensuring the electrical connection between the electromagnetic shielding film and the ground layer of the circuit board.

[0050] In the above embodiment, the conductive spike portions 311 can be distributed regularly or irregularly on the surface of the conductive base portion 310. In this embodiment, the shapes of the conductive spike portions 311 are the same, and / or the distances between the conductive spike portions 311 are the same. Preferably, the shapes of the plurality of conductive spike portions 311 are the same, and the plurality of conductive spike portions 311 are evenly distributed on the surface of the conductive base portion 310. In addition, at least one side of the shielding layer 3 is a undulating structure. For example, the side of the shielding layer close to the adhesive film layer is a undulating structure, which can improve the bending performance of the shielding layer, enhance the piercing ability of the side of the shielding layer close to the adhesive film layer on the adhesive film layer, and also improve the adhesive capacity of this side of the shielding layer.

[0051] It should be noted that Figure 3 and Figure 4 The shape of the conductive protrusion 31 in is only exemplary. Due to differences in process means and parameters, the conductive protrusion 31 can also be in other shapes such as cluster shape, icicle shape, stalactite shape, dendritic shape, etc. In addition, the conductive protrusion 31 in the embodiments of the present invention is not limited by the illustration and the above shapes. As long as the conductive protrusion 31 has the functions of piercing and conducting electricity, it is within the protection scope of the present invention.

[0052] It should be noted that the shielding layer 3 in this embodiment can be a single-layer structure or a multi-layer structure. When the shielding layer 3 is a single layer, a conductive protrusion 31 is provided on the surface of the shielding layer 3 close to the adhesive film layer 4; when the shielding layer 3 is a multi-layer, a conductive protrusion 31 can also be provided on the surface of each layer of the shielding layer 3 close to the adhesive film layer 4. In addition, according to the actual production and application needs, the shielding layer 3 in this embodiment can be set in a grid shape, a foamed shape, etc.

[0053] In the embodiment of the present invention, in order to further ensure the connection between the electromagnetic shielding film and the ground layer of the circuit board, the adhesive film layer 4 in this embodiment includes an adhesive layer containing conductive particles. By including an adhesive layer containing conductive particles in the adhesive film layer 4, the conductivity of the adhesive film layer 4 is improved, thereby further ensuring the connection between the electromagnetic shielding film and the ground layer of the circuit board. Of course, the adhesive film layer 4 can include an adhesive layer without conductive particles to reduce the insertion loss of the circuit board with the electromagnetic shielding film.

[0054] It should be noted that the conductive particles can be separated conductive particles or large particle conductive particles formed by aggregation; when the conductive particles are separated conductive particles, the grounding conductivity of the adhesive film layer 4 can be further improved; while when the conductive particles are large particle conductive particles formed by aggregation, the piercing strength can be increased.

[0055] Please refer to Figure 5 , the electromagnetic shielding film in this embodiment further includes a protective film layer 5, and the protective film layer 5 is provided on the surface of the adhesive film layer 4 away from the shielding layer 3. Since the protective film layer 5 has a protective effect, it can ensure that the adhesive film layer 4 is not scratched or damaged during use. Among them, the protective film layer 5 includes a PPS film layer, a PEN film layer, a polyester film layer, a polyimide film layer, a film layer formed after curing of epoxy resin ink, a film layer formed after curing of polyurethane ink, a film layer formed after curing of modified acrylic resin, or a film layer formed after curing of polyimide resin. Among them, when the electromagnetic shielding film is laminated onto the circuit board, the protective film layer 5 needs to be peeled off first.

[0056] Specifically, when the electromagnetic shielding film includes a carrier layer 1, an insulating layer 2, a shielding layer 3, an adhesive film layer 4, and a protective film layer 5, the preparation method of the electromagnetic shielding film includes:

[0057] 1) Prepare the carrier layer 1;

[0058] 2) Form an insulating layer 2 on one surface of the carrier layer 1;

[0059] 3) Form a shielding layer 3 on the surface of the insulating layer 2 away from the carrier layer 1;

[0060] 4) A glue film layer 4 is formed by coating glue on the side of the shielding layer 3 away from the insulating layer 2;

[0061] 5) A protective film layer 5 is bonded to the side of the glue film layer 4 away from the shielding layer 3.

[0062] For the convenience of understanding the above invention solution, here, three specific embodiments are provided and these specific embodiments are tested: Specific Embodiment 1:

[0064] An electromagnetic shielding film includes a carrier layer 1, an insulating layer 2, and a shielding layer 3; the carrier layer 1 is disposed on one side of the insulating layer 2, and the shielding layer 3 is disposed on the side of the insulating layer 2 away from the carrier layer 1; the roughness Rz of the side of the carrier layer 1 close to the insulating layer 2 is 0.5 micrometers. Among them, the material of the carrier layer 1 is PET, the material of the insulating layer 2 is epoxy resin, and the insulating layer 2 may be formed on one side of the carrier layer 1.

[0065] Test results: After testing, before the electromagnetic shielding film of this embodiment is pressed onto the circuit board, when the carrier layer 1 is peeled off, the tensile force between the carrier layer 1 and the insulating layer 2 is 0.24 N / cm; after the electromagnetic shielding film of this embodiment is pressed onto the circuit board, when the carrier layer 1 is peeled off, the tensile force between the carrier layer 1 and the insulating layer 2 is 0.06 N / cm.

[0066] It can be seen that by applying the electromagnetic shielding film of this embodiment, it can be ensured that the carrier layer 1 is not easily detached, so as to protect the insulating layer 2, and at the same time, the carrier layer 1 can be stably peeled off under a certain applied force, so as to facilitate use. Specific Embodiment 2:

[0068] An electromagnetic shielding film includes a carrier layer 1, an insulating layer 2, and a shielding layer 3; the carrier layer 1 is disposed on one side of the insulating layer 2, and the shielding layer 3 is disposed on the side of the insulating layer 2 away from the carrier layer 1; the roughness Rz of the side of the carrier layer 1 close to the insulating layer 2 is 1.5 micrometers. Among them, the material of the carrier layer 1 is PET, the material of the insulating layer 2 is epoxy resin, and the insulating layer 2 may be formed on one side of the carrier layer 1.

[0069] Test results: After testing, before the electromagnetic shielding film of this embodiment is pressed onto the circuit board, when the carrier layer 1 is peeled off, the tensile force between the carrier layer 1 and the insulating layer 2 is 0.34 N / cm; after the electromagnetic shielding film of this embodiment is pressed onto the circuit board, when the carrier layer 1 is peeled off, the tensile force between the carrier layer 1 and the insulating layer 2 is 0.09 N / cm.

[0070] Thus, by applying the electromagnetic shielding film of this embodiment, it can be ensured that the carrier layer 1 is not easily detached, so as to protect the insulating layer 2, and at the same time, the carrier layer 1 can be stably peeled off under the application of a certain force, thereby facilitating use. Specific Embodiment Three:

[0072] An electromagnetic shielding film includes a carrier layer 1, an insulating layer 2, and a shielding layer 3; the carrier layer 1 is disposed on one surface of the insulating layer 2, and the shielding layer 3 is disposed on the surface of the insulating layer 2 away from the carrier layer 1; the roughness Rz of the surface of the carrier layer 1 close to the insulating layer 2 is 10.25 micrometers. Among them, the material of the carrier layer 1 is PET, the material of the insulating layer 2 is epoxy resin, and the insulating layer 2 can be formed on one surface of the carrier layer 1.

[0073] Test results: After testing, before the electromagnetic shielding film of this embodiment is pressed onto the circuit board, when peeling the carrier layer 1, the tensile force between the carrier layer 1 and the insulating layer 2 is 1.13 N / cm; after the electromagnetic shielding film of this embodiment is pressed onto the circuit board, when peeling the carrier layer 1, the tensile force between the carrier layer 1 and the insulating layer 2 is 0.1 N / cm.

[0074] Thus, by applying the electromagnetic shielding film of this embodiment, it can be ensured that the carrier layer 1 is not easily detached, so as to protect the insulating layer 2, and at the same time, the carrier layer 1 can be stably peeled off under the application of a certain force, thereby facilitating use. Specific Embodiment Four:

[0076] An electromagnetic shielding film includes a carrier layer 1, an insulating layer 2, and a shielding layer 3; the carrier layer 1 is disposed on one surface of the insulating layer 2, and the shielding layer 3 is disposed on the surface of the insulating layer 2 away from the carrier layer 1; the roughness Rz of the surface of the carrier layer 1 close to the insulating layer 2 is 7.8 micrometers. Among them, the material of the carrier layer 1 is PET, the material of the insulating layer 2 is epoxy resin, and the insulating layer 2 can be formed on one surface of the carrier layer 1.

[0077] Test results: After testing, before the electromagnetic shielding film of this embodiment is pressed onto the circuit board, when peeling the carrier layer 1, the tensile force between the carrier layer 1 and the insulating layer 2 is 2.57 N / cm; after the electromagnetic shielding film of this embodiment is pressed onto the circuit board, when peeling the carrier layer 1, the tensile force between the carrier layer 1 and the insulating layer 2 is 0.05 N / cm.

[0078] Thus, by applying the electromagnetic shielding film of this embodiment, it can be ensured that the carrier layer 1 is not easily detached, so as to protect the insulating layer 2, and at the same time, the carrier layer 1 can be stably peeled off under the application of a certain force, thereby facilitating use. Specific Embodiment Five:

[0080] An electromagnetic shielding film includes a carrier layer 1, an insulating layer 2, and a shielding layer 3; the carrier layer 1 is disposed on one side of the insulating layer 2, and the shielding layer 3 is disposed on the side of the insulating layer 2 away from the carrier layer 1; the roughness Rz of the side of the carrier layer 1 close to the insulating layer 2 is 20 micrometers. Wherein, the material of the carrier layer 1 is PET, the material of the insulating layer 2 is epoxy resin, and the insulating layer 2 can be formed on one side of the carrier layer 1.

[0081] Test results: After testing, before the electromagnetic shielding film of this embodiment is laminated to the circuit board, when peeling the carrier layer 1, the tensile force between the carrier layer 1 and the insulating layer 2 is 2.93 N / cm; after the electromagnetic shielding film of this embodiment is laminated to the circuit board, when peeling the carrier layer 1, the tensile force between the carrier layer 1 and the insulating layer 2 is 1.57 N / cm.

[0082] Thus, by applying the electromagnetic shielding film of this embodiment, it can be ensured that the carrier layer 1 is not easily detached, so as to protect the insulating layer 2, and at the same time, the carrier layer 1 can be stably peeled off under the application of a certain force, thereby facilitating use.

[0083] In summary, the roughness Rz of the side of the carrier layer close to the insulating layer is 0.5 - 20 micrometers (such as 0.5, 1.5, 10.25, 7.8, 20 micrometers). By applying the electromagnetic shielding film of this embodiment, it can be ensured that the carrier layer is not easily detached and can be stably peeled off under the application of a certain force, without making the carrier layer and the insulating layer adhere too closely. After laminating the electromagnetic shielding film to the circuit board, the carrier layer can be stably peeled off under the application of a certain force, thereby facilitating use.

[0084] See Figure 6 , another embodiment of the present invention further provides a circuit board, which includes a circuit board body 6 and the electromagnetic shielding film described in any of the above embodiments; the electromagnetic shielding film is laminated with the circuit board body 6; the side of the shielding layer 3 away from the insulating layer 2 is electrically connected to the ground layer of the circuit board body 6.

[0085] Preferably, the circuit board body 6 is one of a flexible single-sided, flexible double-sided, flexible multi-layer, and rigid-flexible board.

[0086] In an embodiment of the present invention, the rough surface of the shielding layer 3 can pierce the adhesive film layer 4 and connect with the ground layer of the circuit board body 6 when the electromagnetic shielding film is pressed onto the circuit board body 6, thereby ensuring the ground layer connection between the shielding layer 3 and the circuit board body 6, thereby achieving the goal of introducing the interference charges in the shielding layer 3 into the ground, avoiding the accumulation of interference charges to form an interference source that affects the normal operation of the circuit board.

[0087] Specifically, the circuit board of the embodiment of the present invention is applied with the electromagnetic shielding film, and the roughness Rz of the side of the carrier layer 1 close to the insulating layer 2 is 0.5-20 microns, so that the carrier layer 1 is not easy to fall off and can be stably peeled off when a certain force is applied. In addition, since the roughness Rz of the side of the carrier layer 1 close to the insulating layer 2 is 0.5-20 microns, compared with the carrier layer 1 with a flat surface structure, when the electromagnetic shielding film and the circuit board are pressed together, the carrier layer 1 is not easy to move horizontally to a large extent during the pressing process, so it is not easy to cause the electromagnetic shielding film to move horizontally as a whole due to the horizontal movement of the carrier layer 1 when the electromagnetic shielding film is pressed onto the circuit board, and the electromagnetic shielding film can be pressed onto the corresponding position of the circuit board. By making the side of the shielding layer 3 close to the adhesive film layer 4 a rough surface, the rough surface of the shielding layer 3 can have piercing ability. Moreover, the rough surface of the shielding layer 3 can enhance the bonding force between the shielding layer 3 and the circuit board, so that the electromagnetic shielding film is not easy to be delaminated. Moreover, when the electromagnetic shielding film is pressed together with the circuit board, since the side of the shielding layer 3 close to the adhesive film layer 4 is a rough surface, and since the amount of adhesive per unit area on the rough surface of the shielding layer 3 is not too much, the adhesive of the adhesive film layer 4 is not easy to move horizontally on the rough surface of the shielding layer 3 when the shielding film is pressed together, so it is not easy for the adhesive to shift and cause obvious adhesive overflow on the edge of the circuit board, so the circuit board after the shielding film is pressed together has a good appearance. In addition, since the side of the shielding layer 3 close to the adhesive film layer 4 is a rough surface, the adhesive material constituting the adhesive film layer 4 is squeezed into the concave position of the rough surface of the shielding layer 3, increasing the amount of adhesive. On the one hand, it is not easy to cause the board to explode, avoiding the problem of high-temperature explosion of the existing electromagnetic shielding film due to insufficient adhesive capacity, thereby effectively ensuring the grounding of the electromagnetic shielding film, thereby extracting the interference charge; on the other hand, it can prevent the adhesive from overflowing to the edge of the circuit board during pressing, so that the circuit board after the shielding film is pressed together has a good appearance.

[0088] As described above, it is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims described above.

Claims

1. An electromagnetic shielding film, characterized in that, It includes a carrier layer, an insulating layer and a shielding layer; The carrier layer is disposed on one side of the insulating layer, and the shielding layer is disposed on the side of the insulating layer away from the carrier layer; The roughness Rz of the side of the carrier layer close to the insulating layer is 0.5 - 20 microns; the ratio of the roughness Rz of the side of the carrier layer close to the insulating layer to the thickness of the insulating layer is 0.125 - 2; the tensile force between the carrier layer and the insulating layer is 0.03 - 2.93 N / cm.

2. The electromagnetic shielding film according to claim 1, wherein The roughness Rz of the side of the carrier layer close to the insulating layer is 1.5 - 7.8 microns.

3. The electromagnetic shielding film according to claim 1, wherein The thickness of the carrier layer is 7 - 150 microns.

4. The electromagnetic shielding film according to claim 1, wherein The insulating layer is formed on one side of the carrier layer, and the roughness Rz of the side of the insulating layer close to the carrier layer is 0.9 - 18 microns.

5. The electromagnetic shielding film according to claim 1, wherein, The electromagnetic shielding film further includes an adhesive film layer; the adhesive film layer is disposed on the side of the shielding layer away from the insulating layer.

6. The electromagnetic shielding film according to claim 5, wherein, The adhesive film layer includes an adhesive layer containing conductive particles; or, the adhesive film layer includes an adhesive layer without conductive particles.

7. The electromagnetic shielding film according to claim 5, wherein Conductive protrusions are provided on the side of the shielding layer close to the adhesive film layer.

8. A circuit board, characterized in that, It includes a circuit board body and the electromagnetic shielding film according to any one of claims 1 - 7; the electromagnetic shielding film is pressed together with the circuit board body; the side of the shielding layer away from the insulating layer is electrically connected to the ground layer of the circuit board body.

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