Electromagnetic shield film and circuit board

Abstract

The application 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 and a shielding layer; the shielding layer is arranged on one side of the insulating layer; and the roughness Sku of the side of the insulating layer, which is far away from the shielding layer, is 0.5-50. The application can effectively enhance the bonding strength between the insulating layer of the electromagnetic shielding film and the reinforcing plate, thereby effectively reducing the delamination phenomenon between the reinforcing plate and the insulating layer when the reinforcing plate is attached to the electromagnetic shielding film.

Description

TECHNICAL FIELD

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

[0002] With the rapid development of electronic industry, electronic products further develop towards miniaturization, light weight and high density assembly, which greatly promotes the development of flexible circuit board, thereby realizing the integration of component device and wire connection. The flexible circuit board can be widely applied to mobile phone, liquid crystal display, communication and aerospace industries.

[0003] Under the impetus of the international market, functional flexible circuit board dominates the flexible circuit board market, and an important indicator for evaluating the performance of functional flexible circuit board is electromagnetic shielding (EMI Shielding). With the integration of functions of mobile phones and other communication equipment, the internal components thereof are rapidly high-frequency and high-speed. For example, in addition to the original audio transmission function, the camera function has become a necessary function, and WLAN (Wireless Local Area Networks), GPS (Global Positioning System) and Internet access functions have been popularized. In addition, the integration of future sensing components makes the trend of rapid high-frequency and high-speed components inevitable. Under the drive of high frequency and high speed, the problems of electromagnetic interference inside and outside the components, signal attenuation in transmission, insertion loss and jitter gradually become serious.

[0004] At present, the electromagnetic shielding film commonly used in the existing circuit board includes an insulating layer and a shielding layer. The shielding layer is connected with the ground layer of the circuit board, and then the interference charge is guided into the ground layer of the circuit board, thereby realizing shielding.

[0005] The present inventor found in the implementation of the present application that the prior art has the following technical problems: due to the poor roughness of the insulating layer of the electromagnetic shielding film, when the reinforcing plate is attached to the circuit board with the electromagnetic shielding film of the above structure, the reinforcing plate cannot be stably attached to the circuit board, which leads to easy delamination. SUMMARY

[0006] In view of the above problems, the purpose of the present application is to provide an electromagnetic shielding film and a circuit board, which can effectively enhance the bonding strength between the insulating layer of the electromagnetic shielding film and the reinforcing plate, thereby effectively reducing the delamination phenomenon between the reinforcing plate and the insulating layer when the reinforcing plate is attached to the electromagnetic shielding film.

[0007] In order to achieve the above purpose, an embodiment of the present application provides an electromagnetic shielding film, which comprises an insulating layer and a shielding layer.

[0008] The shielding layer is arranged on one side of the insulating layer;

[0009] The roughness Sku of the side of the insulating layer away from the shielding layer is 0.5-50.

[0010] As an improvement of the above-mentioned solution, the roughness Sku of the side of the insulating layer away from the shielding layer is 1-25.

[0011] As an improvement of the above-mentioned solution, the roughness Sku of the side of the insulating layer away from the shielding layer is 2-9.6.

[0012] As an improvement of the above-mentioned solution, the electromagnetic shielding film further comprises a carrier layer; the carrier layer is arranged on the side of the insulating layer away from the shielding layer.

[0013] As an improvement of the above-mentioned solution, the insulating layer is formed on one side of the carrier layer, and the ratio of the roughness Sku of the side of the carrier layer to the thickness of the insulating layer is 0.25-5.

[0014] As an improvement of the above-mentioned solution, the electromagnetic shielding film further comprises a glue film layer; the glue film layer is arranged on the side of the shielding layer away from the insulating layer.

[0015] As an improvement of the above-mentioned solution, the side of the shielding layer close to the glue film layer is provided with conductive protrusions.

[0016] As an improvement of the above-mentioned solution, the shielding layer is provided with through holes penetrating through its upper and lower surfaces.

[0017] As an improvement of the above-mentioned solution, the aperture of the through holes is 0.1-10 microns.

[0018] In order to solve the same technical problem, another embodiment of the present application further provides a circuit board comprising a circuit board body and the electromagnetic shielding film as claimed in any one of the above-mentioned solutions; the electromagnetic shielding film is pressure-bonded with the circuit board body; the side of the shielding layer away from the insulating layer is electrically connected with the ground layer of the circuit board body.

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

[0020] The roughness of the one side of the insulation layer away from the shielding layer is 0.5-50, so that the one side of the insulation layer away from the shielding layer has better bonding performance, thereby enhancing the bonding strength between the one side of the insulation layer and the reinforcing plate, so that the reinforcing plate is not prone to delamination with the insulation layer when the reinforcing plate is attached to the one side of the insulation layer, and the reinforcing plate is not prone to large horizontal movement on the one side of the insulation layer, thereby effectively reducing the problem of deviation of the attachment position caused by displacement of the reinforcing plate. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. Obviously, the drawings described in the following are only some of the embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

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

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

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

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

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

[0027] Figure 6 is a structural schematic diagram of a circuit board provided by an embodiment of the present application;

[0028] Wherein, 1, insulation layer; 2, shielding layer; 3, carrier layer; 4, adhesive film layer; 5, protective film layer; 6, circuit board body; 21, conductive protrusion. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0030] In the description and claims of the application, and unless otherwise specified, all numbers are to be understood as modified in all instances by the term "about". The use of "about" in connection with a given value means that the value is the stated value, plus or minus a reasonable range of error. Additionally, the use of "at least one" in the description and claims of the application is intended to mean one or more, unless otherwise indicated. Unless otherwise indicated, the use of "or" in the description and claims of the application is intended to mean "and / or", that is, "and / or", unless the context clearly indicates otherwise. Unless otherwise indicated, the use of "an" is intended to be inclusive of "one or more", unless the context clearly indicates otherwise. Unless otherwise indicated, the use of "one or more" is intended to be inclusive of "at least one", unless the context clearly indicates otherwise.

[0031] In addition, the terms first, second, etc. in the description and claims are only used to distinguish the description of the same technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features, and also not necessarily describing the order or time sequence. The terms are interchangeable where appropriate. Therefore, the features defined as "first" and "second" can be explicitly or implicitly included at least one of the features.

[0032] Referring to Figure 1 An embodiment of the present application provides an electromagnetic shielding film, comprising an insulating layer 1 and a shielding layer 2; the shielding layer 2 is arranged on one side of the insulating layer 1; the roughness Sku of the side of the insulating layer 1 away from the shielding layer 2 is 0.5-50.

[0033] The insulating layer 1 can effectively electrically isolate the shielding layer 2 from the outside, thereby ensuring the electromagnetic shielding effect of the shielding layer 2.

[0034] In the embodiment of the present application, since the sharpness of the roughness of the side of the insulating layer 1 away from the shielding layer 2 is 0.5-50, the side of the insulating layer 1 away from the shielding layer 2 has better bonding performance, thereby enhancing the bonding strength between the side of the insulating layer 1 and the reinforcing plate. Thus, when the reinforcing plate is attached to the side of the insulating layer 1, the reinforcing plate and the insulating layer 1 are less likely to delaminate, and the reinforcing plate is less likely to move horizontally on the side of the insulating layer 1 by a large amplitude, thereby effectively reducing the occurrence of deviation in the attachment position caused by displacement of the reinforcing plate.

[0035] It should be noted that the roughness Sku is a parameter for judging the sharpness of the roughness shape. In addition, the test standard of the roughness Sku is ISO25178.

[0036] In the embodiment, in order to ensure that the shielding layer 2 has good electrical conductivity, the shielding layer 2 comprises 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 comprises 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. The alloy shielding layer is made of any two or more of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold.

[0037] Further, the roughness Sku of the surface of the insulating layer 1 away from the shielding layer 2 is 1-25.

[0038] Specifically, in the embodiment, the roughness Sku of the surface of the insulating layer 1 away from the shielding layer 2 is 2-9.6.

[0039] In the embodiment, the sharpness of the roughness of the surface of the insulating layer 1 away from the shielding layer 2 is 2-9.6, which can further improve the bonding performance of the surface of the insulating layer 1 away from the shielding layer 2, thereby further reducing the delamination phenomenon between the reinforcing plate and the insulating layer 1 when the reinforcing plate is attached to the electromagnetic shielding film. In addition, the surface of the insulating layer 1 away from the shielding layer 2 has better surface tension, thereby improving the adhesion of the printing ink on the surface of the insulating layer 1. When printing characters on the surface of the insulating layer 1, the printing ink can be firmly attached thereto and is not easy to bleed, thereby enabling the characters to be clearly displayed.

[0040] Further, the dyne value of the surface of the insulating layer 1 away from the shielding layer 2 is greater than or equal to 28, so that the printing ink has better adhesion on the surface of the insulating layer 1 away from the shielding layer 2, thereby further reducing the bleeding phenomenon of the printing ink when printing the ink on the surface of the electromagnetic shielding film, thereby achieving better character printing effect.

[0041] In the above embodiment, further, Figure 2 The electromagnetic shielding film further comprises a carrier layer 3, which is arranged on the surface of the insulating layer 1 away from the shielding layer 2. The carrier layer 3 can be used to protect the insulating layer 1 from being damaged by external contact or collision, etc. After the electromagnetic shielding film is high-temperature pressed with the circuit board, the carrier layer 3 needs to be torn off.

[0042] For example, the material of the carrier layer 3 is PET, the English name of which is Polyethylene terephthalate, commonly known as polyester resin. The thickness of the carrier layer 3 is 50 microns.

[0043] In the above embodiment, exemplary, the roughness Sku of the one side of the carrier layer 3 close to the insulating layer 1 is 2-25, so that the bonding strength between the insulating layer 1 and the carrier layer 3 can be improved, and the phenomenon that the insulating layer 1 and the carrier layer 3 are easily separated can be avoided. Moreover, when the insulating layer 1 is formed on the one side of the carrier layer 3 with the roughness Sku of 2-25, the roughness Sku of the one side of the insulating layer 1 away from the shielding layer 2 can be easily 0.5-50, so that the one side of the insulating layer 1 away from the shielding layer 2 has better bonding strength with the printing ink and the reinforcing plate.

[0044] In the above embodiment, exemplary, the carrier layer 3 can be used as the base film for forming the insulating layer 1, and the insulating layer 1 is formed on the one side of the carrier layer 3.

[0045] Specifically, the ratio of the roughness Rz of the one side of the carrier layer 3 close to the insulating layer 1 to the thickness of the insulating layer 1 is 0.25-5, so that when the insulating layer 1 is formed on the one side of the carrier layer 3, the roughness Sku of the one side of the insulating layer 1 away from the shielding layer 2 can be easily 0.5-50.

[0046] In the above embodiment, further, referring to Figure 2 , the electromagnetic shielding film further comprises a glue film layer 4, and the glue film layer 4 is arranged on the one side of the shielding layer 2 away from the insulating layer 1.

[0047] The material of the glue film layer 4 is selected from the following: modified epoxy resin, acrylic, modified rubber, and modified thermoplastic polyimide.

[0048] In the embodiment, the rough surface of the shielding layer 2 is close to the adhesive film layer 4, so that after the electromagnetic shielding film is pressed to the circuit board, the rough surface of the shielding layer 2 can effectively pierce the adhesive film layer 4 to realize effective electrical connection with the ground layer of the circuit board, so that the interference circuit of the shielding layer 2 can be effectively guided to the ground layer of the circuit board, thereby effectively improving the shielding performance of the electromagnetic shielding film 2. Moreover, the rough surface of the shielding layer 2 can enhance the bonding strength between the shielding layer 2 and the circuit board, so that the electromagnetic shielding film is not easy to delaminate. In addition, the adhesive film layer 4 can effectively maintain the bonding strength between the electromagnetic shielding film and the circuit board, so that the electromagnetic shielding film and the circuit board are not easy to have the phenomenon of explosion. Moreover, when the electromagnetic shielding film is pressed to the circuit board, since the rough surface of the shielding layer 2 is close to the adhesive film layer 4, the adhesive material in the adhesive film layer 4 is extruded into the recessed position of the rough surface of the shielding layer 2, thereby increasing the adhesive capacity. On the one hand, the phenomenon of explosion is not easy to occur, and the problem of explosion of the existing electromagnetic shielding film due to insufficient adhesive capacity at high temperature is avoided, thereby effectively ensuring the grounding of the electromagnetic shielding film to guide the interference charge out. On the other hand, the overflow of the adhesive to the edge of the circuit board during pressing can be prevented, so that the circuit board after pressing the shielding film has a good appearance.

[0049] Exemplarily, the rough surface of the insulating layer 1 is close to the shielding layer 2, so that the bending resistance of the insulating layer 1 can be improved, thereby improving the bending resistance of the electromagnetic shielding film. In addition, when the shielding layer 2 is formed on one surface of the insulating layer 1, since the thickness of the shielding layer 2 is constant, the shielding layer 2 will follow the rough surface of the insulating layer 1, so that the rough surface of the shielding layer 2 close to the adhesive film layer 4.

[0050] In the above embodiment, further, referring to Figure 3 , the shielding layer 2 is provided with a through hole penetrating through the upper and lower surfaces thereof. By providing the through hole penetrating through the shielding layer 2, when the electromagnetic shielding film is pressed to the circuit board at high temperature, the volatile gas generated in the adhesive film layer 4 can be effectively exhausted through the through hole of the shielding layer 2, so as to avoid the difficulty in exhausting the volatile gas in the adhesive film layer 4 at high temperature, thereby 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, and further ensuring the grounding of the electromagnetic shielding film and guiding the interference charge out.

[0051] In the 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 exhaust the volatile gas in the adhesive film layer 4 during high-temperature pressing.

[0052] In the embodiment, the number of the through holes on the shielding layer 2 is 1-1000 per square centimeter. By setting the number of the through holes to 1-1000, the volatile substances in the adhesive film layer 4 can be discharged through enough through holes at high temperature, so that the volatile gas in the adhesive film layer 4 can be easily discharged at high temperature, and the electromagnetic shielding film is prevented from being separated from the ground layer of the circuit board due to the blistering and delamination of the electromagnetic shielding film, so that the electromagnetic shielding film is grounded and the interference charge is effectively discharged.

[0053] In the 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 setting 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 to 1%-70%, the electromagnetic shielding effect of the shielding layer 2 is not affected by too many through holes.

[0054] As an example, see Figure 4 The shielding layer 2 is provided with conductive protrusions 21 on the side close to the adhesive film layer 4, so that the shielding layer 2 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.

[0055] Specifically, the number of the conductive protrusions with a longitudinal height greater than 5um on the shielding film per square centimeter of the side of the shielding layer 2 is 1-1000. In this way, 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.

[0056] In the above embodiment, further, the conductive protrusions 21 include a conductive base portion and at least one conductive spike portion; the conductive base portion extends outward from the side of the shielding layer 2, and the at least one conductive spike portion extends outward from the surface of the conductive base portion. The conductive spike portion extending outward from the surface of the conductive base portion can more effectively pierce the adhesive film layer 4, thereby enabling the shielding layer 2 to be better electrically connected to the ground layer of the circuit board.

[0057] Specifically, the protrusion height of the conductive spike portion is 1-10 microns. In this way, the conductive spike portion can 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.

[0058] In the embodiment of the present application, the conductive spikes can be regularly or irregularly distributed on the surface of the conductive base. In the embodiment, the conductive spikes have the same shape, and / or the conductive spikes have the same spacing between each other. Preferably, the conductive spikes have the same shape, and the conductive spikes are uniformly distributed on the surface of the conductive base. In addition, at least one side of the shielding layer 2 is in a relief structure, for example, the side of the shielding layer 2 close to the adhesive film layer 4 is in a relief structure, which can improve the bending performance of the shielding layer 2, and can enhance the piercing ability of the side of the shielding layer 2 close to the adhesive film layer 4 to the adhesive film layer 4, and can also improve the adhesive capacity of the side of the shielding layer 2.

[0059] In a specific implementation, the shielding layer 2 can be formed first, and then the conductive protrusions 21 can be formed on the shielding layer 2 by other processes. Of course, the shielding layer 2 and the conductive protrusions 21 can also be an integral structure formed by one forming process. It should be noted that the material of the conductive protrusions 21 can be the same as the material of the shielding layer 2, or can be different from the material of the shielding layer 2, which is not limited herein.

[0060] It should be noted that the shielding layer 2 of the embodiment can be a single-layer structure or a multi-layer structure. When the shielding layer 2 is single-layer, the conductive protrusions 21 can be arranged on the side of the shielding layer 2 close to the adhesive film layer 4; when the shielding layer 2 is multi-layer, the conductive protrusions 21 can also be arranged on the side of each layer of the shielding layer 2 close to the adhesive film layer 4. In addition, according to the actual production and application needs, the shielding layer 2 of the embodiment can be arranged in a grid shape, a foamed shape, etc.

[0061] It should be noted that, Figure 4 The shape of the conductive protrusions 21 in the above embodiment is only exemplary, and due to the difference in process means and parameters, the conductive protrusions 21 can also be in other shapes such as cluster shape, ice hanging shape, stalactite shape, tree branch shape, etc. In addition, the conductive protrusions 21 in the embodiment of the present application are not limited by the drawings and the above shapes, as long as the conductive protrusions 21 have the functions of piercing and conducting electricity, which are within the protection scope of the present application.

[0062] In the embodiment of the present application, in order to further ensure the connection of the electromagnetic shielding film and the ground layer of the circuit board, the adhesive film layer 4 in the embodiment includes an adhesive layer containing conductive particles. By including the adhesive layer containing conductive particles in the adhesive film layer 4, the conductive capacity of the adhesive film layer 4 is improved, thereby further ensuring the connection of 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, so as to reduce the insertion loss of the circuit board with the electromagnetic shielding film, thereby improving the bending resistance of the circuit board while improving the shielding effectiveness.

[0063] It should be noted that the conductive particles can be mutually separated conductive particles, or can be large particle conductive particles formed by agglomeration; when the conductive particles are mutually separated conductive particles, the grounding conductivity of the adhesive film layer 4 can be further improved; and when the conductive particles are large particle conductive particles formed by agglomeration, the puncture strength can be increased.

[0064] Please refer to Figure 5 The electromagnetic shielding film in the embodiment further comprises a protective film layer 5 arranged on the side of the adhesive film layer 4 away from the shielding layer 2. Since the protective film layer 5 has a protective effect, the adhesive film layer 4 is ensured not to be scratched or damaged during use. When the electromagnetic shielding film is pressed onto the circuit board, the protective film layer 5 is first peeled off. The protective film layer 5 comprises 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.

[0065] Specifically, when the electromagnetic shielding film comprises a carrier layer 3, an insulating layer 1, a shielding layer 2, an adhesive film layer 4 and a protective film layer 5, the preparation method of the electromagnetic shielding film comprises:

[0066] 1) preparing a carrier layer 3;

[0067] 2) forming an insulating layer 1 on one side of the carrier layer 3;

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

[0069] 4) coating adhesive on the side of the shielding layer 2 away from the insulating layer 1 to form an adhesive film layer 4;

[0070] 5) attaching a protective film layer 5 on the side of the adhesive film layer 4 away from the shielding layer 2.

[0071] In order to facilitate the understanding of the above-mentioned invention scheme, the following five specific embodiments are provided and tested: Specific embodiment one:

[0073] An electromagnetic shielding film comprises an insulating layer 1 and a shielding layer 2; the shielding layer 2 is arranged on one side of the insulating layer 1; the roughness Sku of the side of the insulating layer 1 away from the shielding layer 2 is 0.5. The material of the insulating layer 1 is epoxy resin.

[0074] Test result: after testing, the peeling strength between the reinforcing plate and the electromagnetic shielding film is 10.53 N / cm after the reinforcing plate is attached to the insulating layer 1 of the electromagnetic shielding film in the embodiment.

[0075] Therefore, by applying the electromagnetic shielding film of the embodiment, the side of the insulating layer away from the shielding layer has better bonding performance, so that when the reinforcing plate is attached to the side of the insulating layer, the problem of delamination between the reinforcing plate and the insulating layer is less likely to occur, and the reinforcing plate is less likely to move horizontally on the side of the insulating layer, thereby effectively reducing the problem of deviation of the attachment position caused by displacement of the reinforcing plate. Embodiment two:

[0077] An electromagnetic shielding film includes an insulating layer 1 and a shielding layer 2; the shielding layer 2 is arranged on one side of the insulating layer 1; the roughness Sku of the side of the insulating layer 1 away from the shielding layer 2 is 2. The material of the insulating layer 1 is epoxy resin.

[0078] Test results: After testing, the peeling strength between the reinforcing plate and the electromagnetic shielding film is 13.12 N / cm after the reinforcing plate is attached to the insulating layer 1 of the electromagnetic shielding film of the embodiment.

[0079] Therefore, by applying the electromagnetic shielding film of the embodiment, the side of the insulating layer away from the shielding layer has better bonding performance, so that when the reinforcing plate is attached to the side of the insulating layer, the problem of delamination between the reinforcing plate and the insulating layer is less likely to occur, and the reinforcing plate is less likely to move horizontally on the side of the insulating layer, thereby effectively reducing the problem of deviation of the attachment position caused by displacement of the reinforcing plate. Embodiment three:

[0081] An electromagnetic shielding film includes an insulating layer 1 and a shielding layer 2; the shielding layer 2 is arranged on one side of the insulating layer 1; the roughness Sku of the side of the insulating layer 1 away from the shielding layer 2 is 50. The material of the insulating layer 1 is epoxy resin.

[0082] Test results: After testing, the peeling strength between the reinforcing plate and the electromagnetic shielding film is 19.3 N / cm after the reinforcing plate is attached to the insulating layer 1 of the electromagnetic shielding film of the embodiment.

[0083] Therefore, by applying the electromagnetic shielding film of the embodiment, the side of the insulating layer away from the shielding layer has better bonding performance, so that when the reinforcing plate is attached to the side of the insulating layer, the problem of delamination between the reinforcing plate and the insulating layer is less likely to occur, and the reinforcing plate is less likely to move horizontally on the side of the insulating layer, thereby effectively reducing the problem of deviation of the attachment position caused by displacement of the reinforcing plate. Embodiment four:

[0085] An electromagnetic shielding film, comprising an insulating layer 1 and a shielding layer 2; the shielding layer 2 is arranged on one side of the insulating layer 1; the roughness Sku of the side of the insulating layer 1 away from the shielding layer 2 is 25.25. Wherein, the material of the insulating layer 1 is epoxy resin.

[0086] Test results: after testing, the peeling strength between the reinforcing plate and the electromagnetic shielding film is 15.03 N / cm after the reinforcing plate is attached to the insulating layer 1 of the electromagnetic shielding film of the embodiment.

[0087] Therefore, by applying the electromagnetic shielding film of the embodiment, the side of the insulating layer away from the shielding layer has better bonding performance, so that when the reinforcing plate is attached to the side of the insulating layer, the reinforcing plate and the insulating layer are less likely to delaminate, and the reinforcing plate is less likely to move horizontally on the side of the insulating layer, effectively reducing the problem of deviation of the attachment position caused by displacement of the reinforcing plate. Specific embodiment five:

[0089] An electromagnetic shielding film, comprising an insulating layer 1 and a shielding layer 2; the shielding layer 2 is arranged on one side of the insulating layer 1; the roughness Sku of the side of the insulating layer 1 away from the shielding layer 2 is 9.6. Wherein, the material of the insulating layer 1 is epoxy resin.

[0090] Test results: after testing, the peeling strength between the reinforcing plate and the electromagnetic shielding film is 12.2 N / cm after the reinforcing plate is attached to the insulating layer 1 of the electromagnetic shielding film of the embodiment.

[0091] Therefore, by applying the electromagnetic shielding film of the embodiment, the side of the insulating layer away from the shielding layer has better bonding performance, so that when the reinforcing plate is attached to the side of the insulating layer, the reinforcing plate and the insulating layer are less likely to delaminate, and the reinforcing plate is less likely to move horizontally on the side of the insulating layer, effectively reducing the problem of deviation of the attachment position caused by displacement of the reinforcing plate.

[0092] In summary, when the roughness Sku of the side of the insulating layer 1 away from the shielding layer 2 is 0.5-50 (for example, 0.5, 1, 2, 5, 9.6, 10, 15, 20, 25.25, 30, 40, 50), by applying the electromagnetic shielding film of the embodiment, the side of the insulating layer 1 away from the shielding layer 2 has better bonding performance, so that when the reinforcing plate is attached to the side of the insulating layer 1, the reinforcing plate and the insulating layer 1 are less likely to delaminate, and the reinforcing plate is less likely to move horizontally on the side of the insulating layer 1, effectively reducing the problem of deviation of the attachment position caused by displacement of the reinforcing plate.

[0093] Referring to Figure 6 Another embodiment of the present application also provides a circuit board, which comprises a circuit board body 6 and an electromagnetic shielding film according to any one of the above embodiments; the electromagnetic shielding film is pressure-bonded with the circuit board body 6; and the shielding layer 2 is electrically connected with the ground layer of the circuit board body 6.

[0094] Preferably, the circuit board body 6 is one of a flexible single-sided board, a flexible double-sided board, a flexible multi-layer board and a rigid-flexible combined board.

[0095] In the embodiment of the present application, the shielding layer 2 is electrically connected with the ground layer of the circuit board body 6, so that the interference charges in the shielding layer 2 are guided into the ground, avoiding the accumulation of interference charges to form an interference source to affect the normal operation of the circuit board.

[0096] Specifically, the circuit board of the embodiment of the present application has the electromagnetic shielding film, and the sharpness of the roughness of the surface of the insulating layer 1 away from the shielding layer 2 is 0.5-50, so that the surface of the insulating layer 1 away from the shielding layer 2 has better bonding performance, thereby enhancing the bonding strength between the surface of the insulating layer 1 and the reinforcing plate, so that the reinforcing plate is not easy to delaminate from the insulating layer 1, and the reinforcing plate is not easy to move horizontally on the surface of the insulating layer 1, thereby effectively reducing the deviation of the bonding position caused by the displacement of the reinforcing plate.

[0097] The above merely describes the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of the changes or replacements within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An electromagnetic shielding film, characterized by, It includes a carrier layer, an insulating layer, a shielding layer, and an adhesive film layer; The shielding layer is disposed on one side of the insulating layer, the carrier layer is disposed on the side of the insulating layer away from the shielding layer, and the adhesive film layer is disposed on the side of the shielding layer away from the insulating layer; The surface roughness Sku of the side of the insulating layer away from the shielding layer is 0.5-50; The insulating layer is formed on one side of the carrier layer, and the ratio of the roughness Sku of the one side of the carrier layer to the thickness of the insulating layer is 0.25-5.

2. The electromagnetic shielding film according to claim 1, characterized by The surface roughness Sku of the side of the insulating layer away from the shielding layer is 1-25.

3. The electromagnetic shielding film according to claim 1, characterized by The surface roughness Sku of the side of the insulating layer away from the shielding layer is 2-9.

6.

4. The electromagnetic shielding film according to claim 1, characterized in that, The shielding layer has conductive protrusions on the side closest to the adhesive film layer.

5. The electromagnetic shielding film according to claim 1, characterized in that, The shielding layer has through holes that penetrate its upper and lower surfaces.

6. The electromagnetic shielding film according to claim 5, characterized in that, The diameter of the through hole is 0.1-10 micrometers.

7. A circuit board, characterized in that, It includes a circuit board body and an electromagnetic shielding film as described in any one of claims 1-6; the electromagnetic shielding film is pressed together with the circuit board body; the side of the shielding layer away from the insulating layer is electrically connected to the ground layer of the circuit board body.

Images