Electromagnetic shielding film and circuit board

Abstract

The present invention relates to the field of electronic technology, and discloses an electromagnetic shielding film and a circuit board, wherein the electromagnetic shielding film comprises an insulating layer, a shielding layer and an adhesive film layer; the shielding layer is formed on one side of the insulating layer, and the adhesive film layer is arranged on one side of the shielding layer away from the insulating layer; wherein, when the unit of the adhesive weight parameter is grams per square decimeter, the ratio of the roughness Sdr of the side of the insulating layer close to the shielding layer to the adhesive weight parameter of the adhesive film layer is 0.2-20000. The electromagnetic shielding film and circuit board provided by the present invention can simultaneously have the following advantages: good bonding strength with the circuit board and good appearance of the circuit board after being pressed onto the circuit board.

Description

Technical Field

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

[0002] With the rapid development of the electronics industry, electronic products are further developing towards miniaturization, lightness, and high-density assembly, which greatly promotes the development of flexible circuit boards, thereby realizing the integration of component devices and wire connections. Flexible circuit boards can be widely used in industries such as mobile phones, LCD displays, communications, and aerospace.

[0003] Driven by the international market, functional flexible circuit boards dominate the flexible circuit board market, and an important indicator for evaluating the performance of functional flexible circuit boards is electromagnetic interference shielding (EMI shielding). With the integration of functions of mobile phones and other communication devices, 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 a necessary 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 rapid high-frequency and high-speed components is even more inevitable. Driven by high frequency and high speed, the electromagnetic interference inside and outside the components, signal attenuation during transmission, insertion loss and jitter problems are becoming increasingly serious.

[0004] At present, the electromagnetic shielding film commonly used in existing circuit boards includes an insulating layer, a shielding layer and a film layer. The shielding layer is formed on one side of the insulating layer. The side of the shielding layer close to the film layer has roughness and can pierce the film layer to contact and connect with the stratum of the circuit board, thereby introducing the interference charge into the stratum of the circuit board, thereby achieving shielding.

[0005] During the implementation of the present invention, the inventors discovered that the prior art has the following technical problems: in the process of laminating the existing electromagnetic shielding film to the circuit board, the glue of the film layer is likely to overflow from the edge between the electromagnetic shielding film and the circuit board, which will cause the circuit board to have a poor appearance; in order to prevent the glue of the film layer from easily overflowing from the edge between the electromagnetic shielding film and the circuit board during the lamination of the electromagnetic shielding film, the amount of glue in the film layer can be reduced or a smaller pressing force can be applied, but both of these methods will easily cause delamination and bursting between the electromagnetic shielding film and the circuit board. Summary of the invention

[0006] In view of the above problems, the object of the present invention is to provide an electromagnetic shielding film and a circuit board, which can have the following advantages at the same time: good bonding strength with the circuit board and good appearance of the circuit board after being pressed onto the circuit board.

[0007] In order to achieve the above-mentioned object, an embodiment of the present invention provides an electromagnetic shielding film, including an insulating layer, a shielding layer and an adhesive film layer;

[0008] The shielding layer is formed on one side of the insulating layer, and the adhesive film layer is arranged on one side of the shielding layer away from the insulating layer;

[0009] Wherein, when the unit of the adhesive weight parameter is grams per square decimeter, the ratio of the roughness Sdr of the side of the insulating layer close to the shielding layer to the adhesive weight parameter of the adhesive film layer is 0.2-20000.

[0010] As an improvement of the above solution, the roughness Sdr of a side of the insulating layer close to the shielding layer is 0.1%-8000%.

[0011] As an improvement of the above solution, the adhesive weight parameter of the adhesive film layer is 0.01-1 g / dm2.

[0012] As an improvement of the above solution, the ratio of the roughness Sdr of the side of the insulating layer close to the shielding layer to the thickness of the shielding layer is 0.1-335.

[0013] As an improvement of the above solution, the shielding layer is provided with through holes penetrating the upper and lower surfaces thereof.

[0014] As an improvement of the above solution, the average number of through holes per square centimeter on the shielding layer is 1-1000.

[0015] As an improvement of the above solution, the electromagnetic shielding film further comprises a carrier layer; the carrier layer is arranged on a side of the insulating layer away from the shielding layer.

[0016] As an improvement of the above solution, the insulating layer is formed on one side of the carrier layer; the ratio of the roughness Sdr of the one side of the carrier layer to the thickness of the insulating layer is 0.05-12.

[0017] As an improvement of the above solution, a conductive protrusion is provided on a side of the shielding layer close to the adhesive film layer.

[0018] In order to solve the same technical problem, another embodiment of the present invention also provides a circuit board, which includes a circuit board body and the electromagnetic shielding film described in any of the above schemes; the electromagnetic shielding film is pressed onto the circuit board body through the adhesive film layer; the side of the shielding layer close to the adhesive film layer pierces the adhesive film layer and is electrically connected to the ground layer of the circuit board body.

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

[0020] When the electromagnetic shielding film is pressed onto the circuit board, since the shielding layer is formed on one side of the insulating layer, and when the unit of the glue weight parameter is grams per square decimeter, the ratio of the roughness Sdr of the side of the insulating layer close to the shielding layer to the glue weight parameter of the glue film layer is 0.2-20000, so that the glue in the glue film layer can be effectively contained by the side of the shielding layer away from the insulating layer, and it is not easy for a large amount of glue to move to the edge of the circuit board, resulting in obvious glue overflow at the edge between the electromagnetic shielding film and the circuit board, so that the circuit board after the shielding film is pressed The circuit board has a good appearance; in addition, since the ratio of the roughness Sdr of the side of the insulating layer close to the shielding layer to the glue weight parameter of the adhesive film layer is 0.2-20000, the glue amount of the adhesive film layer and the roughness of the side of the shielding layer can have a suitable ratio, so that the shielding layer can be effectively contacted and connected with the ground layer of the circuit board and pressed onto the circuit board to give the circuit board a good appearance. At the same time, there is no need to make the glue amount of the adhesive film layer too small or deliberately reduce the pressing force on the shielding film, and the shielding film and the circuit board can have good bonding strength. In summary, the embodiments of the present invention can have the following advantages at the same time: good bonding strength with the circuit board and good appearance of the circuit board after being pressed onto the circuit board. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the implementation mode will be briefly introduced below. Obviously, the drawings described below are only some implementation modes of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

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

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

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

[0025] Figure 4 is a schematic structural diagram of a fourth electromagnetic shielding film provided by an embodiment of the present invention;

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

[0027] Figure 6 It is a schematic diagram of the structure of a circuit board provided in one embodiment of the present invention.

[0028] Description of the accompanying drawings: 1. Carrier layer; 2. Insulation layer; 3. Shielding layer; 4. Film layer; 5. Protective film layer; 6. Conductive protrusions; 7. Circuit board body. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] In the description of the specification and claims, it is necessary to understand that the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are 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 on the embodiments of the present invention.

[0031] In addition, the terms first, second, etc. in the specification and claims are only used for the purpose of describing the same technical features, and are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated, nor necessarily describing an order or time sequence. The terms are interchangeable where appropriate. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0032] See also Figure 1 , an embodiment of the present invention provides an electromagnetic shielding film, which includes an insulating layer 2, a shielding layer 3 and an adhesive film layer 4;

[0033] The shielding layer 3 is formed on one surface of the insulating layer 2, and the adhesive film layer 4 is provided on the surface of the shielding layer 3 away from the insulating layer 2;

[0034] Wherein, when the unit of the adhesive weight parameter is grams per square decimeter, the ratio of the roughness Sdr of the side of the insulating layer 2 close to the shielding layer 3 to the adhesive weight parameter of the adhesive film layer 4 is 0.2-20000.

[0035] It should be noted that when using the roughness Sdr and the rubber weight parameter for proportional calculation, it is not necessary to convert the percentage value of the roughness Sdr into an actual value, but directly use the percentage value for calculation. For example, if the roughness Sdr is 1%, it does not need to be converted to 0.01, but directly use the value 1 for calculation.

[0036] The insulating layer 2 can effectively electrically isolate the shielding layer 3 from the outside world, thereby ensuring the electromagnetic shielding effect of the shielding layer 3. The shielding layer 3 plays the role of electromagnetic shielding. In addition, the adhesive film layer 4 can allow the electromagnetic shielding film to be attached to the circuit board.

[0037] It can be understood that the side of the insulating layer 2 on which the shielding layer 3 is formed has a certain roughness. 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 along the rough surface of the insulating layer 2, so that the side of the shielding layer 3 close to the film layer 4 can have a certain roughness.

[0038] In the embodiment of the present invention, when the electromagnetic shielding film is pressed onto the circuit board, since the shielding layer 3 is formed on one side of the insulating layer 2, and when the unit of the glue weight parameter is grams per square decimeter, the ratio of the roughness Sdr of the side of the insulating layer 2 close to the shielding layer 3 to the glue weight parameter of the glue film layer 4 is 0.2-20000, so that the glue in the glue film layer 4 can be effectively contained by the side of the shielding layer 3 away from the insulating layer 2, and it is not easy for a large amount of glue to move to the edge of the circuit board, resulting in obvious glue overflow at the edge between the electromagnetic shielding film and the circuit board, thereby making the pressed screen The circuit board after the masking film has a good appearance; in addition, since the ratio of the roughness Sdr of the side of the insulating layer 2 close to the shielding layer 3 and the glue gram weight parameter of the adhesive film layer 4 is 0.2-20000, the amount of glue in the adhesive film layer 4 and the roughness of the side of the shielding layer 3 can have a suitable ratio, so that the shielding layer 3 can be effectively contacted and connected with the ground layer of the circuit board and pressed onto the circuit board to give the circuit board a good appearance, while there is no need to make the amount of glue in the adhesive film layer 4 too small or deliberately reduce the pressing force on the shielding film, and the shielding film and the circuit board can have good bonding strength. In summary, the embodiments of the present invention can have the following advantages at the same time: good bonding strength with the circuit board and good appearance of the circuit board after being pressed onto the circuit board.

[0039] Exemplarily, the adhesive weight parameter of the adhesive film layer 4 is 0.01-1 g / dm2.

[0040] In this embodiment, when the electromagnetic shielding film is pressed onto the circuit board, the adhesive film layer 4 with an adhesive weight of 0.01-1 g / m2 can be easily pierced by the side of the shielding layer 3 away from the insulating layer 2, so that the shielding layer 3 is electrically connected to the ground layer of the circuit board, which can effectively introduce the interference charge of the shielding layer 3 into the ground layer of the circuit board, thereby effectively improving the shielding effectiveness of the electromagnetic shielding layer 3. In addition, the adhesive film layer 4 with an adhesive weight of 0.01-1 g / m2 can effectively maintain the bonding strength between the electromagnetic shielding film and the circuit board, making it less likely for the electromagnetic shielding film and the circuit board to explode. As an example, the adhesive weight parameters of the adhesive film layer 4 are 0.01, 0.05, 0.1, 0.2, 0.505, 0.7, and 1 g / m2.

[0041] Exemplarily, the roughness Sdr of the side of the insulating layer 2 close to the shielding layer 3 is 0.1%-8000%. Preferably, the roughness Sdr of the side of the insulating layer 2 close to the shielding layer 3 is 1%-2000%, and more preferably, the roughness Sdr of the side of the insulating layer 2 close to the shielding layer 3 is 20%-500%.

[0042] It can be understood that the roughness Sdr indicates how much the expansion area (surface area) of the region increases relative to the area of ​​the defined region. Among them, the Sdr of a completely flat surface is 0. For example, the roughness Sdr of one side of the insulating layer 2 is 20%, which means that the area of ​​the test area of ​​the shielding film increases by 20% after it is expanded to be flat compared to before expansion. In addition, the test standard for roughness Sdr is ISO25178.

[0043] In this embodiment, the shielding layer 3 is formed on one side of the insulating layer 2, and the roughness Sdr of the side of the insulating layer 2 close to the shielding layer 3 is 0.1%-8000%, so that in the process of forming the shielding layer 3 on the one side of the insulating layer 2, the shielding layer 3 can follow the ups and downs of the one side of the insulating layer 2, and it is easy to make the side of the shielding layer 3 away from the insulating layer 2 have a roughness that can pierce the film layer 4, so that the shielding layer 3 can be effectively electrically connected to the ground layer of the circuit board. As an example, the roughness Sdr of the side of the insulating layer 2 close to the shielding layer 3 is 0.1%, 0.5%, 1%, 5%, 10%, 50%, 100%, 500%, 1000%, 4000.05%, 5000%, 8000%.

[0044] In the above embodiment, the ratio of the roughness Sdr of the side of the shielding layer 3 close to the adhesive film layer 4 to the thickness of the adhesive film layer 4 is 2-95.

[0045] In this embodiment, the ratio of the roughness Sdr of the side of the shielding layer 3 close to the film layer 4 to the thickness of the film layer 4 is 2-95. Therefore, when the electromagnetic shielding film is pressed onto the circuit board, the side of the shielding layer 3 close to the film layer 4 can effectively pierce the film layer 4 and be electrically connected to the ground layer of the circuit board, thereby effectively introducing the interference charge of the shielding layer 3 into the ground layer of the circuit board, thereby effectively improving the shielding effectiveness of the electromagnetic shielding layer 3.

[0046] The material used for the adhesive film layer 4 is selected from the following: modified epoxy resin, acrylic, modified rubber, modified thermoplastic polyimide. 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. The metal shielding layer includes a single metal shielding layer and / or an alloy shielding layer; 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.

[0047] In the above embodiment, further, the ratio of the roughness Sdr of the side of the insulating layer 2 close to the shielding layer 3 to the thickness of the shielding layer 3 is 0.1-335. In the process of forming the shielding layer 3 on the rough surface of the insulating layer 2, the ratio of the roughness Sdr of the rough surface of the insulating layer 2 to the thickness of the shielding layer 3 is 0.1-335, so that the shielding layer 3 can rise and fall with the rough surface of the insulating layer 2, and it can be easy to make the side of the shielding layer 3 away from the insulating layer 2 have a roughness that can pierce the adhesive film layer 4, so that the shielding layer 3 can be effectively electrically connected to the ground layer of the circuit board.

[0048] In the above embodiment, further, see Figure 2 , the shielding layer 3 is provided with through holes penetrating the upper and lower surfaces thereof. By providing the through holes penetrating the shielding layer 3, when the electromagnetic shielding film is pressed onto the circuit board at high temperature, the volatile gas generated in the adhesive film layer 4 can be effectively exhausted through the through holes of the shielding layer 3, so as to avoid the difficulty of volatiles in the adhesive film layer 4 to be discharged at high temperature, thereby avoiding the electromagnetic shielding film from bubbling and delamination, causing the electromagnetic shielding film to peel off from the ground layer of the circuit board, and further ensuring that the electromagnetic shielding film is grounded and the interference charge is led out.

[0049] 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 gas of the adhesive film layer 4 during the high-temperature pressing process.

[0050] In this embodiment, the average number of through holes per square centimeter on the shielding layer 3 is 1-1000. By setting the number of through holes to 1-1000, it is ensured that the volatiles of the adhesive film layer 4 can be exhausted through enough through holes at high temperatures, thereby preventing the volatile gases in the adhesive film layer 4 from being difficult to be exhausted at high temperatures, thereby preventing the electromagnetic shielding film from bubbling and delamination, causing the electromagnetic shielding film to peel off from the ground layer of the circuit board, thereby ensuring that the electromagnetic shielding film is grounded and effectively extracting the interference charge.

[0051] In this embodiment, the ratio of the sum of the cross-sectional areas of all the through holes in the shielding layer 3 per square centimeter to the cross-sectional area of ​​the shielding layer where the cross section is located is 1% to 70%. By making the ratio of the sum of the cross-sectional areas of all the through holes in the shielding layer 3 per square centimeter to the cross-sectional area of ​​the shielding layer where the cross section is located be 1% to 70%, while ensuring that the volatile gas generated in the adhesive film layer 4 can be effectively exhausted through the through holes of the shielding layer 3, the electromagnetic shielding effect of the shielding layer 3 will not be affected due to too many through holes.

[0052] In the above embodiment, further, see Figure 3 The electromagnetic shielding film further comprises a carrier layer 1; the carrier layer 1 is disposed on the side of the insulating layer 2 away from the shielding layer 3. 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. In addition, the carrier layer 1 can be used as a 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.

[0053] Specifically, the insulating layer 2 is formed on one side of the carrier layer 1; the ratio of the roughness Sdr of the one side of the carrier layer 1 to the thickness of the insulating layer 2 is 0.05-12. In the process of forming the insulating layer 2 on one side of the carrier layer 1, the ratio of the roughness Sdr of the one side of the carrier layer 1 to the thickness of the insulating layer 2 is 0.05-12, so that the insulating layer 2 can rise and fall with the one side of the carrier layer 1, and it can be easy to make the side of the insulating layer 2 away from the carrier layer 1 have a certain roughness, so that the side of the shielding layer 3 away from the insulating layer 2 can finally have a roughness that can pierce the film layer 4, so that the shielding layer 3 can be effectively electrically connected to the ground layer of the circuit board.

[0054] In the above embodiment, further, see Figure 4 A conductive protrusion 6 is provided on the surface of the shielding layer 3 close to the adhesive film layer 4, which can more effectively pierce the adhesive film layer 4, thereby further ensuring that the electromagnetic shielding film is electrically connected to the ground layer of the circuit board.

[0055] Specifically, the number of conductive protrusions 6 with a longitudinal height greater than 5 μm on the shielding film is 1-1000 per square centimeter on the one side of the shielding layer 3. This can more effectively pierce the adhesive film layer 4, thereby further ensuring that the electromagnetic shielding film is electrically connected to the ground layer of the circuit board.

[0056] In the embodiment of the present invention, the conductive protrusions 6 may be regularly or irregularly distributed on the side of the shielding layer 3 close to the adhesive film layer 4. In the present embodiment, the shapes of the plurality of conductive protrusions 6 may be the same or different, and the spacings between the plurality of conductive protrusions 6 may be the same or different. Preferably, the shapes of the plurality of conductive protrusions 6 are the same, and the plurality of conductive protrusions 6 are evenly distributed on the side of the shielding layer 3 of the conductive base part close to the adhesive film layer 4. In a specific implementation, the shielding layer 3 may be formed first, and then the conductive protrusions 6 may be formed on the shielding layer 3 by other processes. Of course, the shielding layer 3 and the conductive protrusions 6 may also be an integral structure formed by a one-time molding process.

[0057] Exemplarily, the conductive protrusion 6 includes a conductive base portion and at least one conductive spike portion; the conductive base portion extends outward from the one surface of the shielding layer 3, and at least one conductive spike portion extends outward from the surface of the conductive base portion. The conductive spike portion extending from the surface of the conductive base portion 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.

[0058] Specifically, the protruding height of the conductive spike portion is 0.1-8 microns, so that the conductive spike portion can effectively pierce the adhesive film layer 4, thereby further ensuring that the electromagnetic shielding film is electrically connected to the ground layer of the circuit board.

[0059] Preferably, the conductive protrusion 6 may be at a certain distance from the outer surface of the adhesive film layer 4, or may be in contact with the outer surface of the adhesive film layer 4 or extend out of the outer surface of the adhesive film layer 4. In addition, the outer surface of the adhesive film layer 4 may be a flat surface without undulations, or an uneven surface with gentle undulations.

[0060] It should be noted that Figure 4 The shape of the conductive protrusion 6 is merely exemplary. Due to differences in process means and parameters, the conductive protrusion 6 may also be in other shapes such as clusters, hanging ice, stalactites, and branches. In addition, the conductive protrusion 6 in the embodiment of the present invention is not limited to the shapes shown in the figure and described above. As long as the conductive protrusion 6 has piercing and conductive functions, it is within the protection scope of the present invention.

[0061] As another example, the conductive protrusion 6 may 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; wherein the single metal particles are made of any one of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold, and the alloy particles are made of any two or more of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold. It should be noted that the conductive protrusion 6 may be the same material as the shielding layer 3, or may be different.

[0062] It should be noted that the shielding layer 3 of this embodiment can be a single-layer structure or a multi-layer structure. When the shielding layer 3 is a single-layer structure, a conductive protrusion can be 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 structure, a conductive protrusion can be provided on the surface of each shielding layer 3 close to the adhesive film layer 4. In addition, according to the needs of actual production and application, the shielding layer 3 of this embodiment can be set in a grid shape, a foam shape, etc.

[0063] 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. The adhesive film layer 4 includes an adhesive layer containing conductive particles to improve the conductivity of the adhesive film layer 4, thereby further ensuring the connection between the electromagnetic shielding film and the ground layer of the circuit board. Of course, in the embodiment of the present invention, the adhesive film layer 4 may include an adhesive layer without conductive particles to reduce the insertion loss of the circuit board with the electromagnetic shielding film, thereby improving the anti-bending property of the circuit board while improving the shielding effectiveness.

[0064] See also Figure 5 As shown, the electromagnetic shielding film in this embodiment also includes a protective film layer 5, and the protective film layer 5 is arranged on the side of the adhesive film layer 4 away from the shielding layer 3. Since the protective film layer 5 has a protective function, it ensures that the insulating layer 2 is not scratched or damaged during use, thereby maintaining the high shielding efficiency of the shielding layer 3. 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 epoxy resin ink is cured, a film layer formed after polyurethane ink is cured, a film layer formed after modified acrylic resin is cured, or a film layer formed after polyimide resin is cured.

[0065] 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 method for preparing the electromagnetic shielding film includes:

[0066] 1) preparing a carrier layer 1;

[0067] 2) forming an insulating layer 2 on one surface of the carrier layer 1;

[0068] 3) forming a shielding layer 3 on a surface of the insulating layer 2 away from the carrier layer 1;

[0069] 4) applying glue on the side of the shielding layer 3 away from the insulating layer 2 to form a glue film layer 4;

[0070] 5) A protective film layer 5 is laminated on the side of the adhesive film layer 4 away from the shielding layer 3 .

[0071] To facilitate the understanding of the above invention, the following five specific embodiments are provided and tested:

[0072] Embodiment 1:

[0073] An electromagnetic shielding film comprises an insulating layer, a shielding layer and an adhesive film layer; the shielding layer is formed on one side of the insulating layer, and the adhesive film layer is arranged on the side of the shielding layer away from the insulating layer; wherein the roughness Sdr of the side of the insulating layer close to the shielding layer is 0.2%, the adhesive gram weight parameter of the adhesive film layer is 1 gram per square decimeter, and the ratio of the roughness Sdr of the side of the insulating layer close to the shielding layer to the adhesive gram weight parameter of the adhesive film layer is 0.2.

[0074] Test results: After the electromagnetic shielding film of this embodiment is pressed onto the circuit board, it is tested that the peel strength between the electromagnetic shielding film of this embodiment and the circuit board is greater than 18.92N / cm, and the length of the glue overflow of the adhesive film layer after the electromagnetic shielding film of this embodiment is pressed onto the circuit board is less than 198μm.

[0075] It can be seen that by applying the electromagnetic shielding film of this embodiment, the electromagnetic shielding film and the circuit board have good bonding strength, and the circuit board can also have a good appearance.

[0076] Embodiment 2:

[0077] An electromagnetic shielding film comprises an insulating layer, a shielding layer and an adhesive film layer; the shielding layer is formed on one side of the insulating layer, and the adhesive film layer is arranged on the side of the shielding layer away from the insulating layer; wherein the roughness Sdr of the side of the insulating layer close to the shielding layer is 0.2%, the adhesive gram weight parameter of the adhesive film layer is 0.01 grams per square decimeter, and the ratio of the roughness Sdr of the side of the insulating layer close to the shielding layer to the adhesive gram weight parameter of the adhesive film layer is 20.

[0078] Test results: After the electromagnetic shielding film of this embodiment is pressed onto the circuit board, it is tested that the peel strength between the electromagnetic shielding film of this embodiment and the circuit board is greater than 11.62N / cm, and the length of the glue overflow of the adhesive film layer after the electromagnetic shielding film of this embodiment is pressed onto the circuit board is less than 70μm.

[0079] It can be seen that by applying the electromagnetic shielding film of this embodiment, the electromagnetic shielding film and the circuit board have good bonding strength, and the circuit board can also have a good appearance.

[0080] Embodiment three:

[0081] An electromagnetic shielding film comprises an insulating layer, a shielding layer and an adhesive film layer; the shielding layer is formed on one side of the insulating layer, and the adhesive film layer is arranged on the side of the shielding layer away from the insulating layer; wherein the roughness Sdr of the side of the insulating layer close to the shielding layer is 200%, the adhesive gram weight parameter of the adhesive film layer is 1 gram per square decimeter, and the ratio of the roughness Sdr of the side of the insulating layer close to the shielding layer to the adhesive gram weight parameter of the adhesive film layer is 200.

[0082] Test results: After the electromagnetic shielding film of this embodiment is pressed onto the circuit board, it is tested that the peel strength between the electromagnetic shielding film of this embodiment and the circuit board is greater than 12.76N / cm, and the length of the glue overflow of the adhesive film layer after the electromagnetic shielding film of this embodiment is pressed onto the circuit board is less than 93μm.

[0083] It can be seen that by applying the electromagnetic shielding film of this embodiment, the electromagnetic shielding film and the circuit board have good bonding strength, and the circuit board can also have a good appearance.

[0084] Embodiment 4:

[0085] An electromagnetic shielding film comprises an insulating layer, a shielding layer and an adhesive film layer; the shielding layer is formed on one side of the insulating layer, and the adhesive film layer is arranged on the side of the shielding layer away from the insulating layer; wherein the roughness Sdr of the side of the insulating layer close to the shielding layer is 200%, the adhesive gram weight parameter of the adhesive film layer is 0.01 grams per square decimeter, and the ratio of the roughness Sdr of the side of the insulating layer close to the shielding layer to the adhesive gram weight parameter of the adhesive film layer is 20000.

[0086] Test results: After the electromagnetic shielding film of this embodiment is pressed onto the circuit board, it is tested that the peel strength between the electromagnetic shielding film of this embodiment and the circuit board is greater than 10.08N / cm, and the length of the glue overflow of the adhesive film layer after the electromagnetic shielding film of this embodiment is pressed onto the circuit board is less than 26μm.

[0087] It can be seen that by applying the electromagnetic shielding film of this embodiment, the electromagnetic shielding film and the circuit board have good bonding strength, and the circuit board can also have a good appearance.

[0088] Embodiment five:

[0089] An electromagnetic shielding film comprises an insulating layer, a shielding layer and an adhesive film layer; the shielding layer is formed on one side of the insulating layer, and the adhesive film layer is arranged on the side of the shielding layer away from the insulating layer; wherein the roughness Sdr of the side of the insulating layer close to the shielding layer is 100.001%, the adhesive gram weight parameter of the adhesive film layer is 0.01 grams per square decimeter, and the ratio of the roughness Sdr of the side of the insulating layer close to the shielding layer to the adhesive gram weight parameter of the adhesive film layer is 10000.1.

[0090] Test results: After the electromagnetic shielding film of this embodiment is pressed onto the circuit board, it is tested that the peel strength between the electromagnetic shielding film of this embodiment and the circuit board is greater than 11.87N / cm, and the length of the glue overflow of the adhesive film layer after the electromagnetic shielding film of this embodiment is pressed onto the circuit board is less than 62μm.

[0091] It can be seen that by applying the electromagnetic shielding film of this embodiment, the electromagnetic shielding film and the circuit board have good bonding strength, and the circuit board can also have a good appearance.

[0092] The above numerical ratios of the roughness Sdr and the rubber weight parameters are only examples, and the numerical ratios may also be other numerical values, such as 1, 10, 100, 1000, 10000, etc.

[0093] See also Figure 6 Another embodiment of the present invention further provides a circuit board, which includes a circuit board body 7 and the electromagnetic shielding film described in any of the above embodiments; the electromagnetic shielding film is pressed together with the circuit board body 7 through the adhesive film layer 4; the side of the shielding layer 3 close to the adhesive film layer 4 pierces the adhesive film layer 4 and is electrically connected to the ground layer of the circuit board body 7.

[0094] Preferably, the circuit board body 7 is one of a flexible single-sided board, a flexible double-sided board, a flexible multi-layer board, and a rigid-flexible board.

[0095] In an embodiment of the present invention, one side of the shielding layer 3 close to the adhesive film layer 4 can pierce the adhesive film layer 4 and connect with the ground layer of the circuit board body 7 when the electromagnetic shielding film is pressed onto the circuit board body 7, thereby ensuring the connection between the ground layer of the shielding layer 3 and the circuit board body 7, thereby achieving the shielding layer 3 and the interference charges in the shielding layer 3 being introduced into the ground, avoiding the accumulation of interference charges to form an interference source that affects the normal operation of the circuit board.

[0096] In the embodiment of the present invention, since the shielding layer 3 is formed on one side of the insulating layer 2, and the unit of the glue weight parameter is grams per square decimeter, the glue in the glue film layer 4 can be effectively contained by the side of the shielding layer 3 away from the insulating layer 2, and it is not easy for a large amount of glue to move to the edge of the circuit board and cause obvious glue overflow at the edge between the electromagnetic shielding film and the circuit board, so that the circuit board after the shielding film is pressed has a good appearance; in addition, since the insulating layer 2 is close to the shielding layer 3 The ratio of the roughness Sdr of one side to the glue weight parameter of the glue film layer 4 is 0.2-20000, so that the glue amount of the glue film layer 4 and the roughness of the one side of the shielding layer 3 can have a suitable ratio, so that the shielding layer 3 can be effectively contacted and connected with the ground layer of the circuit board and pressed onto the circuit board to give the circuit board a good appearance. At the same time, there is no need to make the glue amount of the glue film layer 4 too small or deliberately reduce the pressing force on the shielding film, and the shielding film and the circuit board can have good bonding strength. In summary, the embodiment of the present invention can have the following advantages at the same time: good bonding strength with the circuit board and good appearance of the circuit board after being pressed onto the circuit board.

[0097] The above is only a specific embodiment 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 any technician familiar with the art within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. An electromagnetic shielding film, characterized in that: Including insulation layer, shielding layer and film layer; The shielding layer is formed on one side of the insulating layer, and the adhesive film layer is arranged on one side of the shielding layer away from the insulating layer; Among them, when the unit of the glue weight parameter is grams per square decimeter, the ratio of the roughness Sdr of the side of the insulating layer close to the shielding layer to the glue weight parameter of the film layer is 0.2-20000, and when the roughness Sdr and the glue weight parameter are used for proportional calculation, the percentage value of the roughness Sdr is directly used for calculation; the ratio of the roughness Sdr of the side of the shielding layer close to the film layer to the thickness of the film layer is 2-95, and the thickness of the film layer is in microns.

2. The electromagnetic shielding film according to claim 1, characterized in that The shielding layer is provided with through holes penetrating the upper and lower surfaces thereof.

3. The electromagnetic shielding film according to claim 2, wherein: The average number of through holes per square centimeter on the shielding layer is 1-1000.

4. The electromagnetic shielding film according to claim 1, characterized in that The roughness Sdr of a side of the insulating layer close to the shielding layer is 0.1%-8000%.

5. The electromagnetic shielding film according to claim 1, characterized in that The adhesive weight parameter of the adhesive film layer is 0.01-1 g / dm2.

6. The electromagnetic shielding film according to claim 1, characterized in that The ratio of the roughness Sdr of the side of the insulating layer close to the shielding layer to the thickness of the shielding layer is 0.1-335.

7. The electromagnetic shielding film according to claim 1, characterized in that The electromagnetic shielding film further comprises a carrier layer; the carrier layer is arranged on a side of the insulating layer away from the shielding layer.

8. The electromagnetic shielding film according to claim 7, characterized in that The insulating layer is formed on one side of the carrier layer; the ratio of the roughness Sdr of the one side of the carrier layer to the thickness of the insulating layer is 0.05-12.

9. The electromagnetic shielding film according to claim 1, characterized in that A conductive protrusion is arranged on one side of the shielding layer close to the adhesive film layer.

10. A circuit board, characterized in that: It comprises a circuit board body and the electromagnetic shielding film as described in any one of claims 1-9; the electromagnetic shielding film is pressed onto the circuit board body through the adhesive film layer; a side of the shielding layer close to the adhesive film layer pierces the adhesive film layer and is electrically connected to the ground layer of the circuit board body.

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