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 insulating layer close to the carrier layer is 0.5 - 20 microns; the ratio of the roughness Rz of the surface of the carrier layer close to the insulating layer to the roughness Rz of the surface of the insulating layer close to the carrier layer is 0.025 - 40. 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, thus facilitating 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 electronics industry, electronic products are further moving towards miniaturization, lightweight, and high-density assembly, which greatly promotes the development of flexible printed circuit boards, thus realizing the integration of component devices and wire connections. Flexible printed circuit boards 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 circuit boards dominate the flexible printed circuit board market, and an important indicator for evaluating the performance of functional flexible printed circuit boards is electromagnetic shielding (Electromagnetic Interference Shielding, abbreviated as EMI Shielding). With the integration of functions of communication devices such as mobile phones, their internal components are rapidly becoming high-frequency and high-speed. For example: In addition to the original audio transmission function, the camera function has become an essential function of 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 high-frequency and high-speed is even more inevitable. The problems of electromagnetic interference inside and outside components, signal attenuation during transmission, and insertion loss and jitter caused by high frequency and high speed are gradually becoming serious.

[0004] Currently, the commonly used electromagnetic shielding films for existing circuit boards include 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 detached. Summary of the Invention

[0006] In view of the above problems, an object 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 detached, so as to protect the insulating layer, and at the same time, the carrier layer can be stably peeled off under a certain force, thus facilitating use.

[0007] To achieve the above object, 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 insulating layer close to the carrier layer is 0.5 - 20 microns;

[0010] The ratio of the roughness Rz of the side of the carrier layer close to the insulating layer to the roughness Rz of the side of the insulating layer close to the carrier layer is 0.025 - 40.

[0011] As an improvement to the above solution, the roughness Rz of the side of the insulating layer close to the carrier layer is 1 - 10 microns.

[0012] As an improvement to the above solution, the tensile force between the carrier layer and the insulating layer is 0.01 - 3 N / cm.

[0013] As an improvement to the above solution, the roughness Rz of the side of the carrier layer close to the insulating layer is 0.6 - 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] 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 roughness Rz of the side of the insulating layer close to the carrier layer is 0.6 - 18 microns.

[0018] 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 0.05 - 4.5.

[0019] As an improvement to the above solution, the ratio of the roughness Rz of the side of the insulating layer close to the carrier layer to the thickness of the carrier layer is 0.005 - 0.5.

[0020] 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 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.

[0021] 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:

[0022] When the roughness Rz of the surface of the insulating layer close to the carrier layer is 0.5 - 20 microns, and the ratio of the roughness Rz of the surface of the carrier layer close to the insulating layer to the roughness Rz of the surface of the insulating layer close to the carrier layer is 0.025 - 40, it can be ensured that the carrier layer is not easily detached before the electromagnetic shielding film is laminated onto the circuit board, thus playing a role in protecting the insulating layer. At the same time, after the electromagnetic shielding film is laminated onto the circuit board, the carrier layer and the insulating layer will not be too closely adhered, and the carrier layer can be stably peeled off under a certain applied force, which is convenient for use. Moreover, by making the roughness Rz of the surface of the insulating layer close to the carrier layer be 0.5 - 20 microns, the surface tension of the insulating layer can also be improved, and when printing ink on the insulating layer, the ink will not spread. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] 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.

[0024] Figure 1 It is a schematic structural diagram of the first electromagnetic shielding film provided by an embodiment of the present invention;

[0025] Figure 2 It is a schematic structural diagram of the second electromagnetic shielding film provided by an embodiment of the present invention;

[0026] Figure 3 It is a schematic structural diagram of the third electromagnetic shielding film provided by an embodiment of the present invention;

[0027] Figure 4 It is a schematic structural diagram of the fourth electromagnetic shielding film provided by an embodiment of the present invention;

[0028] Figure 5 It is a schematic structural diagram of the conductive protrusion provided by an embodiment of the present invention;

[0029] Figure 6 It is a schematic structural diagram of the fifth electromagnetic shielding film provided by an embodiment of the present invention;

[0030] Figure 7 It is a schematic structural diagram of the circuit board laminated with the electromagnetic shielding film provided by an embodiment of the present invention.

[0031] Among them, 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. Specific embodiments

[0032] 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.

[0033] In the description of the specification and 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, and 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, and therefore cannot be understood as a limitation to the embodiments of the present invention.

[0034] In addition, the terms first, second, etc. in the specification and 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 are interchangeable under appropriate circumstances. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of the features.

[0035] 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 insulating layer 2 close to the carrier layer 1 is 0.5 - 20 microns; the ratio of the roughness Rz of the surface of the carrier layer 1 close to the insulating layer 2 to the roughness Rz of the surface of the insulating layer 2 close to the carrier layer 1 is 0.025 - 40.

[0036] In an embodiment of the present invention, when the roughness Rz of the surface of the insulating layer 2 close to the carrier layer 1 is 0.5 - 20 microns, and the ratio of the roughness Rz of the surface of the carrier layer 1 close to the insulating layer 2 to the roughness Rz of the surface of the insulating layer 2 close to the carrier layer 1 is 0.025 - 40, it can effectively ensure that the carrier layer 1 is not easily detached before the electromagnetic shielding film is laminated onto the circuit board, thereby protecting the insulating layer 2. At the same time, after the electromagnetic shielding film is laminated onto the circuit board, the carrier layer 1 and the insulating layer 2 will not be too closely adhered, and the carrier layer 1 can be stably peeled off under a certain force, which is convenient for use. Moreover, since the ratio of the roughness Rz of the surface of the carrier layer close to the insulating layer to the roughness Rz of the surface of the insulating layer close to the carrier layer is 0.025 - 40, compared with the carrier layer and insulating layer with a flat surface structure, when the electromagnetic shielding film is laminated with the circuit board, the carrier layer 1 is not likely to have a large horizontal movement during the lamination process, so 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 the electromagnetic shielding film is laminated onto the circuit board, and the electromagnetic shielding film can be laminated at the corresponding position on the circuit board. In addition, by making the roughness Rz of the surface of the insulating layer 2 close to the carrier layer 1 be 0.5 - 20 microns, the surface tension of the insulating layer 2 can be improved, and when printing ink on the insulating layer 2, the ink will not spread. For example, in an application, when printing characters on the surface of the insulating layer, the characters can be clearly displayed.

[0037] Preferably, the roughness Rz of the surface of the insulating layer close to the carrier layer is 0.6 - 18 microns. More preferably, the roughness Rz of the surface of the insulating layer 2 close to the carrier layer 1 is 1 - 10 microns.

[0038] 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.

[0039] Among them, the material of the carrier layer 1 is 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.

[0040] In this embodiment, the tensile force between the carrier layer 1 and the insulating layer 2 is 0.01 - 3 N / cm. By setting the tensile force between the carrier layer 1 and the insulating layer 2 to 0.01 - 3 N / cm, the problem of reverse release (i.e., 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.

[0041] In this embodiment, the roughness Rz of the surface of the carrier layer close to the insulating layer is 0.6 - 18 microns, which can ensure that the carrier layer 1 does not easily fall off before laminating the electromagnetic shielding film onto the circuit board, thereby playing a role in protecting the insulating layer 2. At the same time, after laminating the electromagnetic shielding film onto the circuit board, the carrier layer 1 can be stably peeled off under a certain applied force, which is convenient for use.

[0042] In this embodiment, the thickness of the carrier layer 1 is 7 - 150 microns, and the thickness of the insulating layer is 3 - 25 microns. 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, collision, etc. Among them, when the thickness of the carrier layer 1 is 50 microns, it has better protection ability and can perfectly protect the insulating layer 2 from being damaged by external contact, 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.

[0043] In this embodiment, 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 0.05 - 4.5, and the ratio of the roughness Rz of the surface of the insulating layer 2 close to the carrier layer 1 to the thickness of the carrier layer is 0.005 - 0.5. During the process of forming the insulating layer 2 on one side of the carrier layer 1, 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.

[0044] In this embodiment, the roughness Rz of the surface of the insulating layer 2 close to the shielding layer 3 is 0.5 - 20 microns, which can improve the anti-bending property of the insulating layer 2, thereby improving the anti-bending performance of the electromagnetic shielding film. In addition, when forming the shielding layer 3 on one side of the insulating layer 2, since the thickness of the shielding layer 3 is certain, the roughness Rz of the surface of the shielding layer 3 close to the adhesive film layer can also be 0.5 - 20 microns.

[0045] In this embodiment, the roughness Rz of the surface of the insulating layer 2 close to the shielding layer 3 is 0.5 - 20 microns. Among them, 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 roughness Rz of the surface of the insulating layer 2 close to the shielding layer 3 is 0.5 - 20 microns, which can improve the bonding strength between the insulating layer 2 and the shielding layer 3 and avoid the phenomenon that the insulating layer 2 and the shielding layer 3 are prone to peeling off.

[0046] Further, referring to Figure 2 , the electromagnetic shielding film further includes an adhesive film layer 4; the adhesive film layer 4 is disposed on the surface of the shielding layer 3 away from the insulating layer 2. The electromagnetic shielding film is pressed and bonded to the circuit board body through the adhesive film layer 4; the surface of the shielding layer 3 close to the adhesive film layer 4 pierces through the adhesive film layer 4 and is electrically connected to the ground layer of the circuit board body.

[0047] Among them, the materials used for the adhesive film layer 4 are selected from the following: modified epoxy resins, acrylics, modified rubbers, modified thermoplastic polyimides.

[0048] In the embodiment of the present invention, the roughness Rz of the surface of the shielding layer 3 close to the adhesive film layer 4 is 0.5 - 20 microns. In this way, when the electromagnetic shielding film is pressed and bonded to the circuit board, the surface of the shielding layer 3 close to the adhesive film layer 4 can effectively pierce through the adhesive film layer 4. Moreover, the roughness Rz of the shielding layer 3 is 0.5 - 20 microns, which can enhance the bonding force between the shielding layer 3 and the circuit board, making the electromagnetic shielding film not easily delaminate. And when the electromagnetic shielding film is pressed and bonded to the circuit board, since the roughness Rz of the surface of the shielding layer 3 close to the adhesive film layer 4 is 0.5 - 20 microns, the adhesive of the adhesive film layer 4 is not easily displaced horizontally to a large extent on the surface of the shielding layer 3 during the pressing of the shielding film, so it is not easy to have the problem of obvious adhesive overflow at the edge of the circuit board, so that the circuit board after pressing the shielding film has a good appearance. In addition, since the roughness Rz of the surface of the shielding layer 3 close to the adhesive film layer 4 is 0.5 - 20 microns, the adhesive substances constituting the adhesive film layer 4 are squeezed into the concave positions on the surface of the shielding layer 3, increasing the adhesive capacity. On the one hand, it is not easy to have the phenomenon of board explosion, avoiding the problem of high-temperature board explosion caused by insufficient adhesive capacity of the existing electromagnetic shielding film, and effectively ensuring the grounding of the electromagnetic shielding film, thereby leading out the interfering charges; 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 pressing the shielding film has a good appearance.

[0049] Further, referring to Figure 3, a through hole penetrating the upper and lower surfaces is provided on the shielding layer 3. By providing a through hole penetrating the upper and lower surfaces on the shielding layer 3, when the electromagnetic shielding film is hot-pressed onto the circuit board, the volatile gases generated in the adhesive film layer 4 can be effectively emitted through the through holes of the shielding layer 3, so that the electromagnetic shielding film will not have problems such as blistering and delamination.

[0050] In this embodiment, the aperture of the through hole is 0.1 - 10 microns. By setting the aperture of the through hole to 0.1 - 10 microns, it can be ensured that the through hole can smoothly discharge the volatile gases in the adhesive film layer 4 during the hot pressing process.

[0051] In this embodiment, the number of through holes per square centimeter of the shielding layer 3 is 1 - 1000. By setting the number of through holes to 1 - 1000, it is ensured that the volatiles in the adhesive film layer can exhaust through a sufficient number of the through holes at high temperature, thereby avoiding the difficulty of discharging the volatile gases in the adhesive film layer at high temperature, and further avoiding the peeling between the electromagnetic shielding film and the ground layer of the circuit board caused by the blistering and delamination of the electromagnetic shielding film, so as to ensure that the electromagnetic shielding film is grounded and effectively conducts the interfering charges.

[0052] In this embodiment, the ratio of the sum of the cross-sectional areas of all the through holes per square centimeter of the shielding layer 2 to the cross-sectional area of the shielding layer where the cross-section is located is 1% - 70%. By making the ratio of the sum of the cross-sectional areas of all the through holes per square centimeter of the shielding layer to the cross-sectional area of the shielding layer where the cross-section is located be 1% - 70%, it can not only ensure the effective discharge of the volatile gases in the adhesive film layer at high temperature, but also ensure the electromagnetic shielding effect of the shielding layer.

[0053] See Figure 4 , in the embodiment of the present invention, a conductive protrusion 31 is provided on the surface of the shielding layer 3 close to the adhesive film layer 4, so that the adhesive film layer 4 can be more effectively pierced, 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 protrusion 31 and the shielding layer 3 may be the same or different, and the present invention does not make specific limitations here.

[0054] In the above embodiment, further, see Figure 5 , 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 surface of the shielding layer, and at least one conductive spike portion 311 extends outward from the surface of the conductive base portion 310. Among them, the conductive spike portion 311 extending from the surface of the conductive base portion 310 can more effectively pierce the adhesive film layer, so that the shielding layer can be better electrically connected to the ground layer of the circuit board.

[0055] Specifically, the protruding height of the conductive spike portion 311 is 0.1 - 8 micrometers. 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.

[0056] In the above embodiment, the conductive spike portions 311 can be distributed regularly or irregularly on the surface of the conductive matrix 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 matrix 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. This 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 glue holding ability of this side of the shielding layer.

[0057] As another example, the conductive protrusion 31 can be composed of one or more conductive particles. The conductive particles include one or more of metal particles, carbon nanotube particles, and ferrite particles. In addition, the metal particles include single metal particles and / or alloy particles; among them, the single metal particles are made of any one of materials such as aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver, and gold, and the alloy particles are made of any two or more of materials such as aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver, and gold. 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, the conductive protrusion 31 is provided on the side of the shielding layer 3 close to the adhesive film layer 4; when the shielding layer 3 is a multi-layer, the conductive protrusion 31 can also be provided on the side of each 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 as a grid shape, a foam shape, etc.

[0058] 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.

[0059] 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. When the conductive particles are large particle conductive particles formed by aggregation, the piercing strength can be increased.

[0060] Please refer to Figure 6 , the electromagnetic shielding film in this embodiment further includes a protective film layer 5, and the protective film layer 5 is disposed on the side of the adhesive film layer 4 away from the shielding layer 3. The protective film layer 5 has a protective effect to 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 a circuit board, the protective film layer 5 needs to be peeled off first.

[0061] For the convenience of understanding the above invention solution, here, three specific embodiments are provided and these specific embodiments are tested: Specific Embodiment 1:

[0063] 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 insulating layer close to the carrier layer is 0.5 microns, and the ratio of the roughness Rz of the side of the carrier layer close to the insulating layer to the roughness Rz of the side of the insulating layer close to the carrier layer is 0.1:4. 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 side of the carrier layer 1.

[0064] Test results: After testing, before the electromagnetic shielding film of this embodiment is laminated onto a circuit board, when peeling off the carrier layer 1, the tensile force between the carrier layer 1 and the insulating layer 2 is 0.67 N / cm; after the electromagnetic shielding film of this embodiment is laminated onto a circuit board, when peeling off the carrier layer 1, the tensile force between the carrier layer 1 and the insulating layer 2 is 0.05 N / cm.

[0065] 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 the application of a certain force, thus facilitating use. Specific Embodiment 2:

[0067] An electromagnetic shielding film, comprising 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 insulating layer close to the carrier layer is 0.5 microns, and the ratio of the roughness Rz of the side of the carrier layer close to the insulating layer to the roughness Rz of the side of the insulating layer close to the carrier layer is 20:1. 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.

[0068] 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 0.96 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.

[0069] 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, thus facilitating use. Specific Embodiment Three:

[0071] An electromagnetic shielding film, comprising 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 insulating layer close to the carrier layer is 0.5 microns, and the ratio of the roughness Rz of the side of the carrier layer close to the insulating layer to the roughness Rz of the side of the insulating layer close to the carrier layer is 40:1. 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.

[0072] 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 1.12 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 0.1 N / cm.

[0073] 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, thus facilitating use. Specific Embodiment 4:

[0075] An electromagnetic shielding film, comprising 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 insulating layer close to the carrier layer is 10.25 microns, and the ratio of the roughness Rz of the side of the carrier layer close to the insulating layer to the roughness Rz of the side of the insulating layer close to the carrier layer is 0.1:4. 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 may be formed on one side of the carrier layer 1.

[0076] Test results: After testing, before the electromagnetic shielding film of this embodiment is laminated to the circuit board, when peeling off 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 laminated to the circuit board, when peeling off the carrier layer 1, the tensile force between the carrier layer 1 and the insulating layer 2 is 0.19 N / cm.

[0077] It can be seen that by applying the electromagnetic shielding film of this embodiment, it is possible to ensure 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, thus facilitating use. Specific Embodiment 5:

[0079] An electromagnetic shielding film, comprising 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 insulating layer close to the carrier layer is 10.25 microns, and the ratio of the roughness Rz of the side of the carrier layer close to the insulating layer to the roughness Rz of the side of the insulating layer close to the carrier layer is 20:1. 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 may be formed on one side of the carrier layer 1.

[0080] Test results: After testing, before the electromagnetic shielding film of this embodiment is laminated to the circuit board, when peeling off the carrier layer 1, the tensile force between the carrier layer 1 and the insulating layer 2 is 2.63 N / cm; after the electromagnetic shielding film of this embodiment is laminated to the circuit board, when peeling off the carrier layer 1, the tensile force between the carrier layer 1 and the insulating layer 2 is 0.21 N / cm.

[0081] 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, thus facilitating use. Specific Embodiment Six:

[0083] 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 insulating layer close to the carrier layer is 10.25 microns, and the ratio of the roughness Rz of the side of the carrier layer close to the insulating layer to the roughness Rz of the side of the insulating layer close to the carrier layer is 40:1. 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 side of the carrier layer 1.

[0084] 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 2.71 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 0.22 N / cm.

[0085] 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, thus facilitating use. Specific Embodiment Seven:

[0087] 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 insulating layer close to the carrier layer is 20 microns, and the ratio of the roughness Rz of the side of the carrier layer close to the insulating layer to the roughness Rz of the side of the insulating layer close to the carrier layer is 0.1:4. 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 side of the carrier layer 1.

[0088] 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 2.86 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 0.31 N / cm.

[0089] It can be seen that by applying the electromagnetic shielding film of this embodiment, it is possible to ensure 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, thus facilitating use. Specific Embodiment Eight:

[0091] 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 insulating layer close to the carrier layer is 20 microns, and the ratio of the roughness Rz of the surface of the carrier layer close to the insulating layer to the roughness Rz of the surface of the insulating layer close to the carrier layer is 20:1. 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.

[0092] 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 0.36 N / cm.

[0093] It can be seen that by applying the electromagnetic shielding film of this embodiment, it is possible to ensure 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, thus facilitating use. Specific Embodiment Nine:

[0095] 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 insulating layer close to the carrier layer is 20 microns, and the ratio of the roughness Rz of the surface of the carrier layer close to the insulating layer to the roughness Rz of the surface of the insulating layer close to the carrier layer is 40:1. 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.

[0096] Test results: After testing, before the electromagnetic shielding film of this embodiment is laminated onto the circuit board, when peeling the carrier layer 1, the tensile force between the carrier layer 1 and the insulating layer 2 is 2.98 N / cm; after the electromagnetic shielding film of this embodiment is laminated onto the circuit board, when peeling the carrier layer 1, the tensile force between the carrier layer 1 and the insulating layer 2 is 0.45 N / cm.

[0097] 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, thus facilitating use.

[0098] All in all, the roughness Rz of the surface of the insulating layer close to the carrier layer is 0.5 - 20 microns (such as 0.5, 1, 10, 10.25, 20 microns), and the ratio of the roughness Rz of the surface of the carrier layer close to the insulating layer to the roughness Rz of the surface of the insulating layer close to the carrier layer is 0.025 - 40 (such as 0.025, 20, 40). By applying the electromagnetic shielding film of this embodiment, it can be ensured that the carrier layer 1 is not easily detached before laminating the electromagnetic shielding film onto the circuit board, thereby playing a role in protecting the insulating layer 2. At the same time, after laminating the electromagnetic shielding film onto the circuit board, the carrier layer 1 and the insulating layer 2 will not be too closely adhered, and the carrier layer 1 can be stably peeled off under the application of a certain force, thus facilitating use.

[0099] See Figure 7 , 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 one of the above embodiments; the electromagnetic shielding film is laminated with the circuit board body 6; the surface of the shielding layer 3 away from the insulating layer 2 is electrically connected to the ground layer of the circuit board body 6.

[0100] Preferably, the circuit board body 6 is one of a flexible single-sided, flexible double-sided, flexible multi-layer board, and a rigid-flex board.

[0101] In the embodiment of the present invention, the roughness Rz of the surface of the shielding layer 3 close to the adhesive film layer 4 is 0.5 - 20 microns. When the electromagnetic shielding film is laminated with the circuit board body 6, the shielding layer 3 can pierce through the adhesive film layer 4 and be connected to the ground layer of the circuit board body 6, thereby ensuring the connection between the shielding layer 3 and the ground layer of the circuit board body 6, and thus realizing the introduction of interfering charges in the shielding layer 3 into the ground, avoiding the accumulation of interfering charges to form an interference source and affecting the normal operation of the circuit board.

[0102] Specifically, since the circuit board of the embodiment of the present invention is applied with the electromagnetic shielding film, when the roughness Rz of the side of the insulating layer close to the carrier layer is 0.5-20 microns, and the ratio of the roughness Rz of the side of the carrier layer close to the insulating layer to the roughness Rz of the side of the insulating layer close to the carrier layer is 0.025-40, it can effectively ensure that the carrier layer 1 is not easy to fall off before the electromagnetic shielding film is pressed onto the circuit board, so as to protect the insulating layer. At the same time, after the electromagnetic shielding film is pressed onto the circuit board, the carrier layer 1 and the insulating layer 2 will not be too closely attached, and the carrier layer 1 can be stably peeled off when a certain force is applied, so as to facilitate use. Furthermore, since the ratio of the roughness Rz of the side of the carrier layer close to the insulating layer to the roughness Rz of the side of the insulating layer close to the carrier layer is 0.025-40, compared with the carrier layer and the insulating layer with a flat surface structure, when the electromagnetic shielding film is pressed onto the circuit board, 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. In addition, by making the roughness Rz of the side of the insulating layer 2 close to the carrier layer 1 0.5-20 microns, the surface tension of the insulating layer 2 can be improved, and when printing ink on the insulating layer 2, the ink will not spread. By making the roughness Rz of the side of the shielding layer 3 close to the adhesive film layer 4 0.5-20 microns, the side of the shielding layer 3 close to the adhesive film layer 4 can have piercing ability. Moreover, the roughness Rz of the shielding layer 3 is 0.5-20 microns, which 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. In addition, when the electromagnetic shielding film is pressed together with the circuit board, since the roughness Rz of the side of the shielding layer 3 close to the adhesive film layer 4 is 0.5-20 microns, the adhesive of the adhesive film layer 4 is not easy to move horizontally on one side of the shielding layer 3 to a large extent when the shielding film is pressed together, so it is not easy to cause adhesive displacement and cause obvious adhesive overflow at the edge of the circuit board, so that the circuit board after the shielding film is pressed together can have a good appearance. In addition, since the roughness Rz of one side of the shielding layer 3 close to the adhesive film layer 4 is 0.5-20 microns, the adhesive substance constituting the adhesive film layer 4 is squeezed into the recessed position on one side of the shielding layer 3, thereby increasing the adhesive capacity. On the one hand, it is less likely to cause board bursting, thereby avoiding the problem of high-temperature board bursting due to insufficient adhesive capacity of the existing electromagnetic shielding film, thereby effectively ensuring the grounding of the electromagnetic shielding film, thereby conducting away the interference charge; on the other hand, it can prevent the adhesive from overflowing to the edge of the circuit board during lamination, thereby enabling the circuit board after laminating the shielding film to have a good appearance.

[0103] As described above, it is only the specific implementation manner of the present invention. However, 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.

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 insulating layer close to the carrier 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 roughness Rz of the side of the insulating layer close to the carrier layer is 0.025 - 40; the ratio of the roughness Rz of the side of the insulating layer close to the carrier layer to the thickness of the carrier layer is 0.005 - 0.5; the tensile force between the carrier layer and the insulating layer is 0.01 - 3 N / cm.

2. The electromagnetic shielding film according to claim 1, wherein The roughness Rz of the side of the insulating layer close to the carrier layer is 1 - 10 microns.

3. The electromagnetic shielding film according to claim 1, characterized in that, The roughness Rz of the side of the carrier layer close to the insulating layer is 0.6 - 18 microns.

4. The electromagnetic shielding film according to claim 1, characterized in that, 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; The adhesive film layer includes an adhesive layer containing conductive particles; or, the adhesive film layer includes an adhesive layer without conductive particles.

5. The electromagnetic shielding film according to claim 4, wherein, Conductive protrusions are provided on the side of the shielding layer close to the adhesive film layer.

6. The electromagnetic shielding film according to claim 1, characterized in that, The roughness Rz of the side of the insulating layer close to the carrier layer is 0.6 - 18 microns.

7. The electromagnetic shielding film according to claim 1, wherein 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 0.05 - 4.

5.

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 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.

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