Electromagnetic shielding cover and circuit board

Abstract

The invention discloses an electromagnetic shielding case and a circuit board. The electromagnetic shielding case comprises a shielding case body and a metal shielding frame, the shielding cover body comprises a shielding layer and a connecting layer, the shielding layer comprises a first surface close to the connecting layer and a second surface far away from the connecting layer, and a first protruding part protruding towards the connecting layer is formed on the first surface; the first lug boss is used for penetrating through the connecting layer to electrically connect the shielding case body with the metal shielding frame; wherein the interface expansion area ratio Sdr of the first surface is greater than 5%, and the range of the maximum valley depth Sv of the first surface is 4-10 [mu] m. According to the invention, the protruding parts are formed on the surfaces, close to the connecting layers, of the shielding layers in the shielding case body, the grounding mode between the shielding case body and the metal shielding frame is improved, and a dense transverse shielding network is formed, so that electromagnetic waves are prevented from transversely penetrating between the connecting layers, the transverse wave leakage phenomenon is effectively improved, and the working reliability of the circuit board is improved.

Description

TECHNICAL FIELD

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

[0002] Electronic components susceptible to electromagnetic waves are mounted on a circuit board included in an electronic device in the fields of consumer electronics, medical equipment, automobiles, etc. In order to protect these electronic components from electromagnetic waves, a metal cover made of aluminum or stainless steel is used to cover these electronic components by being connected to a ground wiring on the circuit board, and one metal cover can cover multiple electronic components. Such a metal cover is manufactured by sheet metal processing, and there is a limit to thin thickness. Therefore, the metal cover manufactured by sheet metal processing hinders further miniaturization or thinning of the electronic device.

[0003] Currently, a flexible shielding cover is used instead of a metal shielding cover, and a flexible material is used to realize conformal shaping with the electronic components. Although this method can reduce the space occupation, it cannot meet the heat dissipation requirements of the electronic components, and such a shielding cover is only suitable for circuit boards with low electronic component height. If the electronic component height is high or the edge is sharp, the flexible shielding cover is easily damaged during pressing, resulting in shielding cover failure.

[0004] In order to ensure the heat dissipation of the electronic components and the reliability of the shielding cover, a metal shielding frame and a shielding copper foil are currently combined to achieve electromagnetic shielding. Different size holes are formed in the metal shielding frame, and glue is injected to ensure heat dissipation, and then the shielding copper foil is pressed and covered on the hole. This method can avoid damage to the traditional flexible shielding cover caused by heat generated by the electronic components, and has good shielding effect. However, the shielding copper foil currently used is a laminated structure of copper foil and conductive adhesive, and electromagnetic wave leakage will occur at the contact position with the edge of the hole. Electromagnetic wave signals will leak in the plane direction from the conductive adhesive, causing electromagnetic interference and affecting the normal operation of adjacent electronic components. SUMMARY

[0005] The purpose of the embodiment of the present application is to provide an electromagnetic shielding cover and a circuit board. A protruding portion is formed on the surface of the shielding layer close to the connecting layer in the shielding cover body, the grounding mode between the shielding cover body and the metal shielding frame is improved, a dense transverse shielding network is formed, and transverse penetration of electromagnetic waves between the connecting layers is avoided, thereby effectively improving the transverse wave leakage phenomenon and improving the working reliability of the circuit board.

[0006] In order to achieve the above object, the electromagnetic shielding cover provided by the embodiment of the present application comprises a shielding cover body and a metal shielding frame; the shielding cover body comprises a shielding layer and a connecting layer, the shielding layer comprises a first surface close to the connecting layer and a second surface away from the connecting layer, the first surface is formed with a first protruding part protruding towards the connecting layer, and the first protruding part is used for electrically connecting the shielding cover body and the metal shielding frame through the connecting layer; wherein the interface extension area ratio Sdr of the first surface ranges from 5% to 5000%, and the maximum valley depth Sv of the first surface ranges from 4 to 10 μm.

[0007] As an improvement of the above scheme, the roughness Rz of the first surface ranges from 4 to 30 μm.

[0008] As an improvement of the above scheme, the protruding height and the maximum protruding width of the first protruding part satisfy 0.15≤h / d≤3; wherein h represents the protruding height of the first protruding part, and d represents the maximum protruding width of the first protruding part.

[0009] As an improvement of the above scheme, the maximum distance S between two adjacent protrusions in the first protruding part satisfies d / 10≤S≤10*d; wherein d represents the maximum protruding width of the first protruding part.

[0010] As an improvement of the above scheme, in a sliced state, the protruding height h of the first protruding part satisfies 5 μm≤h≤10 μm.

[0011] As an improvement of the above scheme, the maximum protruding width d of the first protruding part satisfies 5 μm≤d≤15 μm.

[0012] As an improvement of the above scheme, the shielding layer comprises a support core and a conductive layer wrapped outside the support core, the support core is made of a non-conductive material, and the support core and the conductive layer jointly form the first protruding part.

[0013] As an improvement of the above scheme, the surface of the conductive layer is formed with conductive particles, the particle size of the conductive particles ranges from 0.5 to 2 μm, and the distance between adjacent conductive particles ranges from 0.2 to 3 μm.

[0014] As an improvement of the above scheme, the second surface is formed with a second protruding part, and the roughness of the second protruding part is smaller than that of the first protruding part.

[0015] As an improvement of the above scheme, the shielding layer is more than two layers, and adjacent shielding layers are connected through the connecting layer.

[0016] As an improvement of the above-mentioned scheme, the second surface of the shielding layer is further provided with an insulating layer.

[0017] As an improvement of the above-mentioned scheme, the dielectric constant ε of the connecting layer satisfies ε≤3.

[0018] As an improvement of the above-mentioned scheme, the connecting layer is any one of fluororubber, modified polyimide, and conductive glue containing conductive particles.

[0019] The embodiment of the present application further provides a circuit board, which comprises the electromagnetic shielding cover according to any one of the above-mentioned schemes, and the electromagnetic shielding cover is arranged on the surface of the circuit board.

[0020] Compared with the prior art, the electromagnetic shielding cover and the circuit board provided by the embodiment of the present application have the beneficial effects that: the electromagnetic shielding cover comprises a shielding cover body and a metal shielding frame; the shielding cover body comprises a shielding layer and a connecting layer, the shielding layer comprises a first surface close to the connecting layer and a second surface away from the connecting layer, a first protruding part protruding towards the connecting layer is formed on the first surface of the shielding layer, the shielding cover body and the metal shielding frame are electrically connected through the first protruding part penetrating through the connecting layer, and the grounding mode between the shielding cover body and the metal shielding frame is improved. Wherein, the interface expansion area ratio Sdr of the first surface of the shielding layer is greater than 5%, and the maximum valley depth Sv of the first surface ranges from 4 to 10 μm, so that a dense transverse shielding network can be formed, thereby avoiding the transverse penetration of electromagnetic waves between the connecting layers, effectively improving the transverse wave leakage phenomenon, and improving the working reliability of the circuit board. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a structural schematic diagram of a preferred embodiment of a shielding cover body in the electromagnetic shielding cover provided by the present application; Figure 2 is a surface topography schematic diagram of a shielding layer in the electromagnetic shielding cover provided by the present application; Figure 3 is a cross-section schematic diagram of a shielding layer in the electromagnetic shielding cover provided by the present application; Figure 4 is a parameter marking schematic diagram of a preferred embodiment of a shielding cover body in the electromagnetic shielding cover provided by the present application; Figure 5 is a structural schematic diagram of another preferred embodiment of a shielding cover body in the electromagnetic shielding cover provided by the present application; Figure 6 is a structural schematic diagram of another preferred embodiment of a shielding cover body in the electromagnetic shielding cover provided by the present application; Figure 7is a structural schematic view of still another preferred embodiment of a shielding body in an electromagnetic shielding case provided by the present application; Figure 8 is a structural schematic view of still another preferred embodiment of a shielding body in an electromagnetic shielding case provided by the present application; In the drawings, the reference signs are as follows: 1, shielding layer; 2, connecting layer; 3, insulating layer; 4, carrier film; 5, protective film. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0023] In the description of the present application, it should be understood that the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0024] In the description of the present application, the terms "first", "second", "third" and the like are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second", "third" and the like can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0025] In the description of the present application, it should be noted that, unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as understood by a person skilled in the art of the technology. The terms used in the specification of the present application are only for the purpose of describing the specific embodiments, and are not intended to limit the present application. For a person of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0026] Please refer to Figures 1 to 3 , Figure 1 is a structural schematic view of still another preferred embodiment of a shielding body in an electromagnetic shielding case provided by the present application; Figure 2is a surface topography diagram of a shielding layer in an electromagnetic shielding cover provided by the present application, Figure 3 is a cross-section diagram of an electromagnetic shielding cover provided by the present application. The electromagnetic shielding cover provided by the present application comprises a shielding cover body and a metal shielding frame. The shielding cover body comprises a shielding layer 1 and a connecting layer 2. The shielding layer 1 comprises a first surface close to the connecting layer 2 and a second surface away from the connecting layer 2. The first surface is formed with a first protruding part protruding towards the connecting layer 2. The first protruding part is used to electrically connect the shielding cover body and the metal shielding frame through the connecting layer 2. The interface expansion area ratio Sdr of the first surface is greater than 5%, and the maximum valley depth Sv of the first surface ranges from 4 to 10 μm.

[0027] Specifically, the electromagnetic shielding cover in the present application comprises a flexible shielding cover body and a rigid metal shielding frame. The shielding cover body comprises a shielding layer 1 and a connecting layer 2. The shielding layer 1 comprises a first surface close to the connecting layer 2 and a second surface away from the connecting layer 2. The first surface of the shielding layer 1 is formed with a first protruding part protruding towards the connecting layer 2. The first protruding part is used to electrically connect the shielding cover body and the metal shielding frame through the connecting layer 2. The connecting layer is a conductive adhesive layer. The thickness of the connecting layer is 1-3 μm higher than the highest protrusion in the first protruding part. The connecting layer completely covers all the protrusions in the first protruding part to protect the shielding layer. When pressed, the first protruding part pierces the connecting layer to electrically connect the shielding cover body and the metal shielding frame.

[0028] It should be noted that the shielding layer 1 in the present application can be a metal foil or a composite material of non-metal and metal. For example, copper foil, iron foil, aluminum foil, gold foil, silver foil, tin foil, nickel foil, chromium foil or alloy foil formed by two or more elements.

[0029] The interface extension area ratio Sdr of the first surface of the shielding layer 1 ranges from 5% to 5000%, and the maximum valley depth Sv of the first surface of the shielding layer 1 ranges from 4 to 10 μm. It should be noted that the interface extension area ratio Sdr refers to how much the extension area (surface area) of the region increases relative to the area of the defined region, which can be measured by a 3D profilometer, and the reference standard is ISO25178. For example, the interface extension area ratio Sdr of the first surface of the shielding layer 1 in the embodiment of the present application is 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 200%, 300%, 400%, 500%, 600%, 700%, 800%, 900%, 1000%, 2000%, 3000%, 4000%, 5000%, and / or an interval formed by any two of the above values. The maximum valley depth Sv refers to the vertical distance from the lowest valley to the center surface in the convex region. For example, the maximum valley depth Sv of the first surface of the shielding layer 1 in the embodiment of the present application ranges from 4, 6, 8, 10 μm, and / or an interval formed by any two of the above values.

[0030] The embodiment of the present application improves the grounding mode between the shielding cover body and the metal shielding frame and the shielding layer structure, electrically connects the shielding cover body and the metal shielding frame through the convex part of the shielding layer, reduces the gap in the connecting layer, and forms a dense transverse shielding network through the dense first convex part, thereby absorbing, reflecting and attenuating the transversely leaked electromagnetic waves, avoiding the transverse penetration of the electromagnetic waves between the connecting layers, effectively improving the wave leakage phenomenon, and improving the working reliability of the circuit board.

[0031] In another preferred embodiment, the roughness Rz of the first surface ranges from 4 to 30 μm.

[0032] Specifically, the embodiment of the present application further limits the roughness of the first surface of the shielding layer 1 to ensure that the roughness of the first surface is in the interval that can ensure sufficient contact and avoid local defects, thereby optimizing the shielding performance. For example, the roughness Rz of the first surface of the shielding layer 1 ranges from 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30 μm, and / or an interval formed by any two of the above values.

[0033] In yet another preferred embodiment, the convex height and the maximum convex width of the first convex part satisfy 0.15≤h / d≤3. Wherein, h represents the convex height of the first convex part; d represents the maximum convex width of the first convex part.

[0034] Specifically, please refer toFigure 4 , Figure 4 is a preferred embodiment of the electromagnetic shielding case provided by the present application. The first protruding part of the first surface of the shielding layer 1 is further limited in the present application to avoid the sharp tip causing local electric field concentration and inducing wave leakage. In the present application, the protruding height h of the first protruding part and the maximum protruding width d satisfy 0.15≤h / d≤3. The protruding height h of the first protruding part is measured as follows: assuming that there are two adjacent high points (e.g. mountain-shaped protrusions) around a protrusion in the first protruding part, the vertical heights of the two high points are determined first; the lower high point is taken as the reference datum; the vertical distance between the lowest point of the protrusion and the lower high point is measured, which is the protruding height h. The maximum protruding width d of the first protruding part is measured as follows: taking the lowest point of a protrusion in the first protruding part as the reference, the horizontal distance between the adjacent highest points on the left and right sides of the protrusion is measured, which is the protruding width; the maximum value of all the protruding widths is taken, which is the maximum protruding width d.

[0035] In another preferred embodiment, the maximum distance S between two adjacent protrusions in the first protruding part satisfies d / 10≤S≤10*d. wherein d represents the maximum protruding width of the first protruding part.

[0036] Specifically, the maximum distance S between two adjacent protrusions in the first protruding part of the first surface of the shielding layer 1 is further limited in the present application to avoid electromagnetic wave leakage from the gap and affect the shielding performance. In the present application, the maximum distance S between two adjacent protrusions in the first protruding part satisfies d / 10≤S≤10*d. It should be noted that the maximum distance S between two adjacent protrusions in the first protruding part refers to the lateral distance between the lowest points of the two adjacent protrusions, which can be observed from above under an electron microscope, and the measurement method of the distance is the lateral distance between the center points of the protrusions, which can be found by using image processing software.

[0037] In another preferred embodiment, the protruding height h of the first protruding part satisfies 5μm≤h≤10μm in the slicing state.

[0038] Specifically, the protruding height of the first protruding part of the first surface of the shielding layer 1 is further limited in the present application to avoid the protrusion being too small and easily deformed under pressure, causing unstable contact area and affecting the shielding performance. In the present application, the protruding height h of the first protruding part is 5, 6, 7, 8, 9, 10μm and / or an interval formed by any two values in the slicing state.

[0039] In another preferred embodiment, the maximum protrusion width d of the first protrusion portion satisfies 5 μm≤d≤15 μm.

[0040] Specifically, the embodiments of the present application further limit the maximum protrusion width of the first protrusion portion on the first surface of the shielding layer 1, so as to avoid that the protrusion is too small to be deformed by pressure, resulting in unstable contact area, and ensure that the number of protrusions per unit area can form a dense transverse shielding network. For example, in the slicing state, the maximum protrusion width d of the first protrusion portion is 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 μm and / or any interval formed by two values.

[0041] In another preferred embodiment, the shielding layer 1 comprises a support core and a conductive layer wrapped on the outer surface of the support core, the support core is a non-conductive material, and the support core and the conductive layer jointly form the first protrusion portion.

[0042] Specifically, the embodiments of the present application shielding layer 1 comprises a support core and a conductive layer wrapped on the outer surface of the support core. The support core is a non-conductive material, has higher mechanical strength and corrosion resistance, can withstand external pressure, vibration or environmental erosion, and provides stable support for the conductive layer. The conductive layer reflects or absorbs electromagnetic waves to prevent external interference from entering the internal circuit and prevent internal signal leakage. The support core and the conductive layer jointly form the first protrusion portion, wherein the support core can be selected from fiber cloth, textile cloth or non-woven fabric material. Specifically, the non-woven fabric material formed by heat bonding method is melted by heating the fiber material, and the welding points are formed at the intersection of the fibers after solidification, and the plane material is fused to form a concave-convex form with original fiber material on the surface in the slicing state. The conductive layer can be formed by vacuum sputtering, spraying, chemical deposition, electroplating or a combination thereof. The support core is immersed in an electrolyte, and the metal ions are reduced and deposited on the protrusion surface by current to form the first protrusion portion.

[0043] When the shielding layer 1 is a conductive non-woven fabric, the method for increasing the protrusion height of the first protrusion portion is as follows: coating the first surface of the shielding layer 1 with glue mixed with filler particles, and leaving the filler particles after drying to form a high roughness surface; sputtering a seed layer on the high roughness surface to increase the protrusion height of the first protrusion portion.

[0044] In another preferred embodiment, the surface of the conductive layer is formed with conductive particles, the particle size of the conductive particles is 0.5-2 μm, and the distance between adjacent conductive particles is 0.2-3 μm.

[0045] Specifically, the surface of the conductive layer in the embodiment of the present application is formed with conductive particles, multiple reflections and scattering occur between the particles when electromagnetic waves are incident, which can prolong the propagation path of electromagnetic waves in the shielding layer, increase the absorption loss, and thus enhance the electromagnetic shielding performance. Moreover, the conductive particles can enhance the adhesion between the conductive layer and the supporting core, and prevent the conductive layer (such as a metal coating) from falling off due to friction. For example, the particle size of the conductive particles in the embodiment of the present application is 0.5, 1, 1.5, 2 μm and / or an interval formed by any two of the values, and the interval between adjacent conductive particles is 0.2, 0.5, 1, 1.5, 2, 2.5, 3 μm and / or an interval formed by any two of the values.

[0046] In yet another preferred embodiment, the second surface of the shielding layer 1 is further provided with an insulating layer 3.

[0047] Specifically, please refer to Figure 7 , Figure 7 is a structural schematic diagram of still another preferred embodiment of a shielding body of an electromagnetic shielding cover provided by the present application. In the embodiment of the present application, the second surface of the shielding layer 1 is further provided with an insulating layer 3 (i.e. a protective layer), which plays an insulating and protective role, avoids permeation through the non-woven fabric during gluing, and ensures stable bonding force.

[0048] In yet another preferred embodiment, the second surface is formed with a second protruding portion, and the roughness of the second protruding portion is less than the roughness of the first protruding portion.

[0049] Specifically, please refer to Figure 5 , Figure 5 is a structural schematic diagram of still another preferred embodiment of a shielding body of an electromagnetic shielding cover provided by the present application. In the embodiment of the present application, the second surface of the shielding layer 1 is formed with a second protruding portion, which is used to improve the bonding force between the shielding layer and the insulating layer, avoid delamination during pressing, and ensure the use reliability of the shielding body. Moreover, the roughness of the second protruding portion is less than the roughness of the first protruding portion, so that the roughening process does not need to be added, which is conducive to reducing the production cost.

[0050] In yet another preferred embodiment, the shielding layer is two or more layers, and adjacent shielding layers are connected through the connecting layer.

[0051] Specifically, please refer to Figure 6 , Figure 6 is a structural schematic diagram of another preferred embodiment of a shielding body of an electromagnetic shielding cover provided by the present application. In the embodiment of the present application, the shielding layer 1 can be two or more layers, and adjacent shielding layers 1 are connected through the connecting layer 2.

[0052] In another preferred embodiment, the shielding case body further comprises a carrier film 4 and / or a protective film 5; The carrier film 4 is arranged on the side of the insulating layer 3 away from the shielding layer 1. The protective film 5 is arranged on the side of the connecting layer 2 away from the shielding layer 1.

[0053] Specifically, please refer to Figure 8 , Figure 8 is a structural schematic diagram of another preferred embodiment of a shielding case body of an electromagnetic shielding case provided by the present application. In the embodiment of the present application, the shielding case body further comprises a carrier film 4, or the shielding case body further comprises a protective film 5, or the shielding case body further comprises a carrier film 4 and a protective film 5. Among them, the carrier film 4 is arranged on the side of the insulating layer 3 away from the shielding layer 1, and plays a supporting role. The insulating layer is formed on the carrier film. The carrier film 4 can also play a high-temperature resistant role to protect the black film layer during pressing. The protective film 5 is arranged on the side of the connecting layer 2 away from the shielding layer 1, and plays a protective role for the connecting layer. The protective film 5 is generally a release film.

[0054] In another preferred embodiment, the dielectric constant ε of the connecting layer 2 satisfies ε≤3; and / or, The connecting layer 2 is any one of fluorine rubber, modified polyimide, and conductive adhesive containing conductive particles.

[0055] Specifically, in the embodiment of the present application, the dielectric constant ε of the connecting layer 2 satisfies ε≤3, so as to reduce the propagation speed of electromagnetic waves in the connecting layer, thereby shortening the equivalent wavelength. Moreover, the low dielectric constant material can reduce the capacitive coupling effect between adjacent signal lines. For example, in a printed circuit board (PCB), the connecting layer with ε≤3 can reduce crosstalk noise by 15%~20%, meeting the demand of high-density wiring. It should be noted that the measurement method of dielectric constant can adopt a flat plate capacitance method and an impedance spectrum method. Among them, the flat plate capacitance method is suitable for solid materials such as fluorine rubber and modified polyimide. The dielectric constant is calculated by measuring the capacitance value of a parallel plate capacitor. For example, the connecting layer material is processed into a circular sheet with a diameter of 20 mm and a thickness of 0.1-1 mm; an LCR tester (such as Keysight E4980A) is used to measure the capacitance C; the dielectric constant ε is calculated according to the formula , where d is the sample thickness, A is the electrode area, epsilon 0 is the vacuum dielectric constant. The impedance spectrum method extracts the dielectric constant by analyzing the frequency dependence of the impedance of the material. For example, the connecting layer sample is placed between electrodes and connected by a circuit; an impedance spectrum is measured by using a frequency scanner; and the dielectric constant ε is calculated by fitting the equivalent circuit model.

[0056] Further, the connecting layer 2 in the embodiment of the present application is any one of fluororubber, modified polyimide, and conductive adhesive containing conductive particles.

[0057] The embodiment of the present application also provides a circuit board, which comprises the electromagnetic shielding cover according to any one of the above embodiments, and the electromagnetic shielding cover is arranged on the surface of the circuit board and covers all components on the circuit board.

[0058] In order to embody the beneficial effects of the electromagnetic shielding cover and the circuit board provided by the embodiment of the present application, the following describes several embodiments and comparative examples.

[0059] Embodiment 1 In this embodiment, the shielding cover body comprises a shielding layer and a connecting layer, and the first surface of the shielding layer close to the connecting layer is formed with a first protruding part protruding towards the connecting layer; wherein the interface expansion area ratio Sdr of the first surface of the shielding layer is 10%, and the maximum valley depth Sv of the first surface is 6 μm.

[0060] Embodiment 2 Different from embodiment 1, in the slicing state, the protruding height h of the first protruding part is 10 μm, the maximum protruding width d of the first protruding part is 5 μm, the protruding height and the maximum protruding width of the first protruding part satisfy h / d=2, and the maximum distance S between adjacent protrusions in the first protruding part satisfies 0.5≤S≤50.

[0061] Embodiment 3 The shielding cover body comprises a shielding layer, a connecting layer and an insulating layer, the first surface of the shielding layer close to the connecting layer is formed with a first protruding part protruding towards the connecting layer, and the second surface of the shielding layer away from the connecting layer is provided with the insulating layer; wherein the roughness Rz of the first surface of the shielding layer is 10 μm, the shielding layer comprises a support core and a conductive layer wrapped outside the support core, and the support core and the conductive layer jointly form the first protruding part; wherein the surface of the conductive layer is formed with conductive particles, the particle size of the conductive particles is 1 μm, and the distance between adjacent conductive particles is 0.5 μm; the second surface of the shielding layer is formed with a second protruding part, and the roughness of the second protruding part is smaller than that of the first protruding part; the dielectric constant ε of the connecting layer is 2.

[0062] Comparative Example 1 In this embodiment, the shielding cover body comprises a shielding layer and a connecting layer which are stacked.

[0063] Comparative Example 2 Different from the comparative example 1, the shielding layer is formed with a first protruding part protruding towards the connecting layer near the first surface of the connecting layer; wherein the protruding height h of the first protruding part is 3 μm, the maximum protruding width d of the first protruding part is 2 μm, and the protruding height and the maximum protruding width of the first protruding part h / d = 1.5.

[0064] Comparative example 3 Different from the comparative example 1, the roughness Rz of the shielding layer near the first surface of the connecting layer is 3 μm.

[0065] The electromagnetic shielding cover provided by the examples 1-3 and the comparative examples 1-3 is covered on the components on the surface of the circuit board, and the transmission loss of the prepared fine circuit is detected, wherein the vector network analyzer (VNA) is used to measure the transmission loss, and the test environment is specifically as follows: the working frequency of 3-5 GHz is used, and the test results are shown in Table 1: Table 1 Test results

[0066] It can be seen from the above Table 1 that the electromagnetic shielding cover prepared by the examples of the present application can avoid the influence of electromagnetic wave leakage on the shielding effectiveness, and can improve the working reliability of the circuit board.

[0067] The above is the preferred embodiment of the present application, it should be noted that for the ordinary skilled in the art, without departing from the principles of the present application, can make a number of improvements and refinements, these improvements and refinements also as the protection scope of the present application.

Claims

1. An electromagnetic shielding cover, characterized in that, The shield includes a shield body and a metal shield frame. The shield body includes a shielding layer and a connecting layer. The shielding layer includes a first surface near the connecting layer and a second surface away from the connecting layer. The first surface has a first protrusion that protrudes toward the connecting layer. The first protrusion is used to electrically connect the shield body to the metal shield frame through the connecting layer. The interface expansion area ratio Sdr of the first surface ranges from 5% to 5000%, and the maximum valley depth Sv of the first surface ranges from 4 to 10 μm.

2. The electromagnetic shielding cover as described in claim 1, characterized in that, The roughness Rz of the first surface is 4~30μm.

3. The electromagnetic shielding cover as described in claim 1, characterized in that, The height of the first protrusion and the maximum width of the protrusion satisfy 0.15≤h / d≤3; Where h represents the protrusion height of the first protrusion; d represents the maximum protrusion width of the first protrusion.

4. The electromagnetic shielding cover as described in claim 3, characterized in that, The maximum distance S between two adjacent protrusions in the first protrusion satisfies d / 10≤S≤10*d; Where d represents the maximum protrusion width of the first protrusion.

5. The electromagnetic shielding cover as described in claim 1, characterized in that, In the sliced ​​state, the protrusion height h of the first protrusion satisfies 5μm≤h≤10μm; and / or, The maximum protrusion width d of the first protrusion satisfies 5μm≤d≤15μm.

6. The electromagnetic shielding cover as described in any one of claims 2-5, characterized in that, The shielding layer includes a support core and a conductive layer wrapped around the outer surface of the support core. The support core is made of a non-conductive material, and the support core and the conductive layer together form the first protrusion.

7. The electromagnetic shielding cover as described in claim 6, characterized in that, The conductive layer has conductive particles formed on its surface. The particle size of the conductive particles is 0.5~2μm, and the spacing between adjacent conductive particles is 0.2~3μm.

8. The electromagnetic shielding cover as described in claim 1, characterized in that, The second surface has a second protrusion, the roughness of the second protrusion being less than the roughness of the first protrusion; and / or, The shielding layer consists of two or more layers, with adjacent shielding layers connected by the connecting layer; and / or, The second surface of the shielding layer is also provided with an insulating layer.

9. The electromagnetic shielding cover as described in claim 1, characterized in that, The dielectric constant ε of the connecting layer satisfies ε≤3; and / or, The connecting layer is any one of fluororubber, modified polyimide, or conductive adhesive containing conductive particles.

10. A circuit board, characterized in that, The circuit board includes an electromagnetic shielding cover as described in any one of claims 1-9, the electromagnetic shielding cover being disposed on the surface of the circuit board.

Images