Electromagnetic shielding cover and circuit board

Abstract

The invention discloses an electromagnetic shielding case and a circuit board. The electromagnetic shielding cover comprises an insulating layer, the thickness of the insulating layer in unit area meets # imgabs0 #, # imgabs1 # is the thickness average value of the insulating layer at any N point, sigma is the thickness standard deviation under N sampling points, and N is larger than or equal to 3. According to the electromagnetic shielding case, the insulating layer has good insulating performance, so that the shielding performance of the electromagnetic shielding case is improved, and the working efficiency of the circuit board is improved.

Description

Technical Field

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

[0002] An electromagnetic shield is a metal shell used for electromagnetic shielding, mainly used to reduce the impact of electromagnetic interference (EMI) and electromagnetic radiation (EMR). Its main function is to block or suppress electromagnetic waves within a specific spatial range to achieve the purpose of shielding interference, protecting electronic equipment and confidential communications. The principle of electromagnetic shielding is mainly based on electromagnetic field theory and the conductive properties of metal materials. Electromagnetic fields are generated by electric charges and currents, and there are a large number of free electrons inside metal materials. These free electrons can generate currents under the action of electromagnetic fields, thereby offsetting the impact of external electromagnetic fields on the internal circuits and components of the equipment. At the same time, the conductive properties of metal materials also give it a good electromagnetic shielding effect, which can effectively absorb and reflect electromagnetic waves.

[0003] At present, the commonly used electromagnetic shielding cover includes a shielding layer and an insulating layer. The shielding layer is electrically connected to the ground of the circuit board, and then the interference charge is introduced into the ground of the circuit board, thereby achieving shielding.

[0004] However, the electromagnetic shielding cover in the prior art has poor insulation performance of the insulation layer, resulting in reduced shielding performance of the electromagnetic shielding cover. When the performance of the electromagnetic shielding cover is reduced, adjacent components on the circuit board may cause interference, affecting the normal operation of the circuit board chips and electronic components. Summary of the invention

[0005] The present invention provides an electromagnetic shielding cover and a circuit board, which can make the insulating layer have better insulating performance, thereby improving the shielding performance of the electromagnetic shielding cover.

[0006] In a first aspect, an embodiment of the present invention provides an electromagnetic shielding cover, comprising: an insulating layer, wherein the thickness of the insulating layer per unit area satisfies:

[0007]

[0008] in, is the average thickness of the insulating layer at any N points, σ ​​is the standard deviation of the thickness at N sampling points, and N≥3.

[0009] Optionally, the thickness of the insulating layer per unit area satisfies:

[0010]

[0011] Among them, d max is the maximum thickness at N sampling points, d min is the minimum thickness value at N sampling points.

[0012] Optionally, within any 600 μm straight line measurement range, the maximum thickness difference between any two points of the insulating layer is less than 5 μm.

[0013] Optionally, the thickness of the insulating layer is in the range of 10 to 20 μm.

[0014] Optionally, the electromagnetic shielding cover further comprises a first shielding layer, and the insulating layer is arranged on a side surface of the first shielding layer; within a unit area, the order of magnitude difference of the measured value of the film surface resistance of the insulating layer away from the side surface of the first shielding layer is within 4 levels.

[0015] Optionally, within a unit area, the measured values ​​of the film surface resistance of the side of the insulating layer away from the first shielding layer are of the same order of magnitude.

[0016] Optionally, the electromagnetic shielding cover further includes a first connection layer, which is arranged on a side of the first shielding layer away from the insulating layer, and the first connection layer is used for grounding to the circuit board.

[0017] Optionally, the electromagnetic shielding cover further includes a conductive layer, and the conductive layer is arranged on a side of the first shielding layer close to and / or away from the first connecting layer.

[0018] Optionally, the electromagnetic shielding cover further includes a second shielding layer and a second connecting layer, the second shielding layer and the second connecting layer are both arranged between the first shielding layer and the first connecting layer, and the second shielding layer is connected to a side of the first shielding layer away from the insulating layer through the second connecting layer.

[0019] Optionally, conductive particles are provided in the first connection layer, and the first shielding layer is electrically connected to the ground of the circuit board at least through the conductive particles; and / or, conductive particles are provided in the second connection layer, and the first shielding layer and the second shielding layer are electrically connected at least through the conductive particles.

[0020] Optionally, a concave-convex portion is provided on a side surface of the insulating layer close to the first shielding layer, and the first shielding layer is arranged in contact with the concave-convex portion.

[0021] The first shielding layer is provided with a plurality of first hollow parts, and the first shielding layer is made of conductive material.

[0022] Optionally, the thickness of the first shielding layer is in the range of 10 to 80 μm; and / or the thickness of the second shielding layer is in the range of 10 to 80 μm.

[0023] Optionally, the first shielding layer includes a first supporting layer and a first metal layer, the first supporting layer is provided with a first hollow portion, and the first metal layer is arranged on at least one surface of the first supporting layer and the inner wall of the first hollow portion; and / or, the second shielding layer includes a second supporting layer and a second metal layer, the second supporting layer is provided with a second hollow portion, and the second metal layer is arranged on at least one surface of the second supporting layer and the inner wall of the second hollow portion.

[0024] In a second aspect, an embodiment of the present invention provides a circuit board, including the electromagnetic shielding cover provided by any embodiment of the present invention.

[0025] The electromagnetic shielding cover of the embodiment of the present invention includes an insulating layer and a first shielding layer. The thickness of the insulating layer per unit area is set to meet the following requirements:

[0026]

[0027] The resistance distribution and electric field distribution of the insulating layer can be made more uniform, thereby improving the insulation performance of the insulating layer, avoiding electrical contact between components, ensuring the shielding performance of the electromagnetic shielding cover, and improving the working efficiency of the circuit board.

[0028] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 is a schematic cross-sectional structure diagram of an electromagnetic shielding cover provided by an embodiment of the present invention;

[0031] Figure 2 is a schematic cross-sectional structure diagram of another electromagnetic shielding cover provided by an embodiment of the present invention;

[0032] Figure 3 is a schematic cross-sectional structure diagram of another electromagnetic shielding cover provided by an embodiment of the present invention;

[0033] Figure 4 is a schematic cross-sectional structure diagram of another electromagnetic shielding cover provided by an embodiment of the present invention;

[0034] Figure 5 is a schematic cross-sectional structure diagram of another electromagnetic shielding cover provided by an embodiment of the present invention;

[0035] Figure 6 is a schematic cross-sectional structure diagram of another electromagnetic shielding cover provided by an embodiment of the present invention;

[0036] Figure 7 is a flow chart of a method for preparing an electromagnetic shielding cover provided by an embodiment of the present invention;

[0037] Figure 8 is a schematic cross-sectional structure diagram of another electromagnetic shielding cover provided by an embodiment of the present invention;

[0038] Fig. 9 is a flow chart of another method for preparing an electromagnetic shielding cover provided by an embodiment of the present invention;

[0039] Fig.10 is a schematic cross-sectional structure diagram of another electromagnetic shielding cover provided by an embodiment of the present invention;

[0040] Fig.11 It is a schematic cross-sectional structure diagram of another electromagnetic shielding cover provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0041] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings 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 should fall within the scope of protection of the present invention.

[0042] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions.

[0043] Figure 1 FIG. 1 is a schematic cross-sectional view of an electromagnetic shielding cover provided by an embodiment of the present invention. Figure 1 As shown, the electromagnetic shielding cover comprises:

[0044] The insulating layer 110 has a thickness per unit area that satisfies:

[0045]

[0046] in, is the average thickness of the insulating layer 110 at any N points, σ ​​is the standard deviation of the thickness at N sampling points, and N≥3.

[0047] Specifically, the embodiment of the present invention does not particularly limit the material of the insulating layer 110, as long as it has insulating properties. Exemplarily, the material of the insulating layer 110 is any one of polyimide, polyvinyl chloride, polyethylene naphthalate, polytetrafluoroethylene, aramid, polyester and anisotropic conductive adhesive. The embodiment of the present invention does not particularly limit the thickness of the insulating layer 110, which can be appropriately set according to the insulating material used. Exemplarily, the thickness of the insulating layer 110 ranges from 10μm to 20μm.

[0048] The thickness of the insulating layer 110 affects the resistance distribution and electric field distribution of the insulating layer 110 , thereby affecting the insulation performance. When the thickness of the insulating layer 110 satisfies formula 1, the resistance distribution of the insulating layer is uniform and the insulation effect is good, thereby improving the working efficiency of the circuit board.

[0049] The electromagnetic shielding cover of the embodiment of the present invention includes an insulating layer and a first shielding layer. The thickness of the insulating layer per unit area is set to meet the following requirements:

[0050]

[0051] The resistance distribution and electric field distribution of the insulating layer can be made uniform, thereby improving the insulation performance of the insulating layer, avoiding electrical contact between electronic components, ensuring the shielding performance of the electromagnetic shielding cover, and improving the working efficiency of the circuit board.

[0052] Based on the above embodiments, continue to refer to Figure 1 Optionally, within a unit area, the thickness of the insulating layer 110 satisfies:

[0053]

[0054] Among them, d max is the maximum thickness at N sampling points, d min is the minimum thickness value at N sampling points.

[0055] Specifically, when the thickness of the insulating layer 110 satisfies both Formula 1 and Formula 2, the thickness uniformity of the insulating layer 110 can be further increased, thereby improving the insulation performance of the insulating layer 110 and improving the shielding performance of the electromagnetic shielding cover.

[0056] Based on the above embodiments, continue to refer to Figure 1Optionally, within any 600 μm linear measurement range, the maximum thickness difference between any two points of the insulating layer 110 is less than 5 μm. This arrangement can further increase the thickness uniformity of the insulating layer 110, thereby improving the insulation performance of the insulating layer 110 and the shielding performance of the electromagnetic shielding cover.

[0057] Based on the above embodiments, continue to refer to Figure 1 Optionally, the electromagnetic shield further comprises a first shielding layer 120, and the insulating layer 110 is disposed on a side of the first shielding layer 120. Within a unit area, the measured value of the film surface resistance of the insulating layer 110 away from the side of the first shielding layer 120 differs by an order of magnitude within 4 levels. Exemplarily, within a unit area, the measured value of the film surface resistance of the insulating layer 110 away from the side of the first shielding layer 120 is 10*10 4 Ω~15*10 8 Ω. Preferably, the measured values ​​of the film surface resistance of the insulating layer 110 away from the first shielding layer 120 are of the same order of magnitude. Exemplarily, the measured value of the film surface resistance of the insulating layer 110 away from the first shielding layer 120 is 10*10 4 Ω~90*10 4 Ω, or 10*10 5 Ω~90*10 5 Ω, or 10*10 6 Ω~90*10 6 This arrangement can make the resistance distribution of the insulating layer 110 more uniform, thereby improving the insulation effect of the insulating layer 110 and improving the shielding performance of the electromagnetic shielding cover.

[0058] The embodiment of the present invention does not specifically limit the material of the first shielding layer 120, as long as it has conductivity. Exemplarily, the material of the first shielding layer 120 can be at least one of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold. The embodiment of the present invention does not specifically limit the thickness of the first shielding layer 120, and it can be appropriately set according to the conductive material used. When the material of the first shielding layer 120 is a metal material, if the thickness of the first shielding layer 120 is too large, the rigidity of the first shielding layer 120 will increase, which is not conducive to the molding and manufacturing of the electromagnetic shielding cover. If the thickness of the first shielding layer 120 is too small, the strength of the first shielding layer 120 may be reduced, it is easy to be damaged, and the electromagnetic shielding effect is weakened. Therefore, the thickness range of the first shielding layer 120 can be set between 10μm and 80μm.

[0059] The first shielding layer 120 may be a single-layer structure or a multi-layer structure. In addition, according to the needs of actual production and application, the first shielding layer 120 may be configured in a grid shape or a foamed shape. Both sides of the first shielding layer 120 may be flat, undulating, or convex, which are not specifically limited in the embodiments of the present invention.

[0060] Figure 2 FIG. 1 is a schematic cross-sectional structure diagram of another electromagnetic shielding cover provided by an embodiment of the present invention. Figure 2 As shown, a concave-convex portion is provided on one side of the insulating layer 110 close to the first shielding layer 120, and the first shielding layer 120 is arranged in contact with the concave-convex portion. Such an arrangement can increase the contact area between the insulating layer 110 and the first shielding layer 120, thereby enhancing the bonding force between the insulating layer 110 and the first shielding layer 120, so that the electromagnetic shielding cover is not prone to blistering and delamination.

[0061] Specifically, the concavo-convex part includes a plurality of convex parts 10 and a plurality of concave parts 11, and the plurality of convex parts 10 and the plurality of concave parts 11 are arranged at intervals. The spacing between each convex part 10 and the adjacent concave parts 11 can be the same or different. In order to further improve the bonding force between the insulating layer 110 and the first shielding layer 120 and improve the conductive efficiency, the spacing between each convex part 10 and the adjacent concave parts 11 in the embodiment of the present invention is the same.

[0062] The shapes of each convex portion 10 may be the same or different; the shapes of each concave portion 11 may be the same or different. Exemplarily, the shapes of each convex portion 10 are the same, and the shapes of each concave portion 11 are the same. Each convex portion 10 is an axisymmetric structure; each concave portion 11 is an axisymmetric structure; of course, each convex portion 10 may also be a non-axisymmetric structure, and each concave portion 11 may also be a non-axisymmetric structure.

[0063] Figure 3 FIG. 1 is a schematic cross-sectional structure diagram of another electromagnetic shielding cover provided by an embodiment of the present invention. Figure 3 As shown, the electromagnetic shielding cover further includes a first connection layer 130 . The first connection layer 130 is disposed on a side of the first shielding layer 120 away from the insulating layer 110 . The first connection layer 130 is used to be grounded to the circuit board.

[0064] The first connection layer 130 can be electrically connected to the ground 100 of the circuit board during the high temperature lamination process. The first connection layer 130 can be a thermoplastic adhesive, a thermosetting adhesive, or a pressure-sensitive adhesive. Exemplarily, the material of the first connection layer 130 can be at least one of bisphenol A epoxy resin, bisphenol S epoxy resin, bisphenol F epoxy resin, acrylic resin, and polyester resin.

[0065] Based on the above embodiments, continue to refer to Figure 3 Optionally, the first connection layer 130 is provided with conductive particles 31, and the first shielding layer 120 is electrically connected to the ground 100 of the circuit board at least through the conductive particles 31. In the embodiment of the present invention, by providing the conductive particles 31 in the first connection layer 130, the conductivity of the first connection layer 130 can be improved, thereby further ensuring the grounding electrical connection between the electromagnetic shielding cover and the circuit board. Of course, the first connection layer 130 can be an adhesive layer without conductive particles to reduce the insertion loss of the circuit board with the electromagnetic shielding cover, thereby improving the circuit while improving the shielding effectiveness.

[0066] The embodiment of the present invention does not limit the composition and shape of the conductive particles 31. Exemplarily, the composition of the conductive particles 31 is at least one of copper, aluminum, titanium, zinc, iron, nickel, chromium, cobalt, silver and gold. The conductive particles 31 can be small conductive particles separated from each other, or large conductive particles aggregated.

[0067] Figure 4 FIG. 1 is a schematic cross-sectional structure diagram of another electromagnetic shielding cover provided by an embodiment of the present invention. Figure 4 As shown, the first shielding layer 120 is provided with a plurality of first hollow portions 12 , and the first shielding layer 120 is made of conductive material.

[0068] Specifically, the first shielding layer 120 includes a first supporting layer 1201 and a first metal layer 1202 . The first supporting layer 1201 is provided with a first hollow portion 12 . The first metal layer 1202 is disposed on at least one surface of the first supporting layer 1201 and an inner wall of the first hollow portion 12 .

[0069] The embodiment of the present invention does not specifically limit the material of the first support layer 1201. Exemplarily, the material of the first support layer 1201 may be a non-woven fabric. The embodiment of the present invention does not specifically limit the thickness of the first support layer 1201, and it may be appropriately set according to the support material used. Exemplarily, the thickness of the first support layer 1201 ranges from 5 μm to 20 μm. Sputtering the first metal layer 1202 on the first support layer 1201 can make the first support layer 1201 conductive. According to actual needs, the first metal layer 1202 can be thickened by vacuum sputtering or electroplating to form the first shielding layer 120.

[0070] The first hollow portion 12 may be a square through hole or a through hole of any other shape. Figure 4Only the square through hole of the first hollow portion 12 is used as an example. By setting a plurality of first hollow portions 12 in the first support layer 1201, the present invention can make the glue material of the first connection layer 130 be squeezed into the first hollow portions 12 when the electromagnetic shielding cover is pressed against the circuit board, thereby enhancing the bonding force between the electromagnetic shielding cover and the circuit board, and avoiding the peeling between the electromagnetic shielding cover and the ground of the circuit board caused by blistering and delamination of the electromagnetic shielding cover.

[0071] Figure 5 FIG. 1 is a schematic cross-sectional structure diagram of another electromagnetic shielding cover provided by an embodiment of the present invention. Figure 5 As shown, the electromagnetic shielding cover further includes a conductive layer 140 , and the conductive layer 140 is disposed on a side of the first shielding layer 120 close to and / or away from the first connection layer 130 .

[0072] Specifically, the embodiment of the present invention does not specifically limit the material of the conductive layer 140. Exemplarily, the material of the conductive layer 140 can be at least one of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold. The embodiment of the present invention does not specifically limit the thickness of the conductive layer 140, which can be appropriately set according to the conductive material used. Exemplarily, the thickness of the conductive layer 140 ranges from 5 μm to 40 μm.

[0073] Continue to refer Figure 5 Optionally, the electromagnetic shielding cover also includes a second connecting layer 150 , the conductive layer 140 and the second connecting layer 150 are both arranged between the first shielding layer 120 and the first connecting layer 130 , and the conductive layer 140 is connected to a side of the first shielding layer 120 away from the insulating layer 110 through the second connecting layer 150 .

[0074] Specifically, the second connection layer 150 may be an adhesive layer containing conductive particles. This arrangement can improve the conductivity of the second connection layer 150, thereby further ensuring the electrical connection between the first shielding layer 120 and the conductive layer 140. Of course, the second connection layer 150 may also be an adhesive layer without conductive particles. This arrangement can reduce the insertion loss of the circuit board with the electromagnetic shielding cover, thereby improving the shielding effectiveness and the bending property of the circuit board.

[0075] Figure 6 FIG. 1 is a schematic cross-sectional structure diagram of another electromagnetic shielding cover provided by an embodiment of the present invention. Figure 6 As shown, the conductive layer 140 may be provided with first through holes 14 that penetrate the upper and lower surfaces thereof. Optionally, the first through holes 14 and the first hollow portions 12 are aligned one by one, and the first through holes 14 and the first hollow portions 12 have the same shape, so that the first connection layer 130 passes through the first through holes 14 and the first hollow portions 12 in sequence to connect with the insulating layer 110.

[0076] Figure 7 is a flow chart of a method for preparing an electromagnetic shielding cover provided by an embodiment of the present invention, which is suitable for preparing Figure 6 Electromagnetic shielding, such as Figure 7 As shown, the preparation method of the electromagnetic shielding cover includes:

[0077] S101, forming an insulating layer on a carrier layer.

[0078] S102 , sputtering a first metal layer on the first supporting layer to form a first shielding layer.

[0079] It should be noted that step S101 and step S102 are executed simultaneously.

[0080] S103, laminating the first shielding layer on the insulating layer, forming a second connecting layer on a side of the first shielding layer away from the insulating layer, and forming a conductive layer on a side of the second connecting layer away from the first shielding layer.

[0081] S104, etching the conductive layer to form a first through hole.

[0082] S105 , forming a first connecting layer on a side of the conductive layer away from the insulating layer.

[0083] The first support layer has a first hollow portion. The carrier layer is a tearable release film, which is only used during the preparation process and can be torn off after the preparation is completed.

[0084] Figure 8 FIG. 1 is a schematic cross-sectional structure diagram of another electromagnetic shielding cover provided by an embodiment of the present invention. Figure 8 As shown, optionally, the electromagnetic shielding cover also includes a second shielding layer 160 and a second connecting layer 150, and the second shielding layer 160 and the second connecting layer 150 are both arranged between the first shielding layer 120 and the first connecting layer 130, and the second shielding layer 160 is connected to a side of the first shielding layer 120 away from the insulating layer 110 through the second connecting layer 150.

[0085] Specifically, the embodiment of the present invention does not particularly limit the material of the second shielding layer 160, as long as it has conductivity. In some embodiments, the second shielding layer 160 includes one or more of a metal shielding layer, a carbon nanotube shielding layer, a ferrite shielding layer, and a graphene shielding layer. Among them, the metal shielding layer includes a single metal shielding layer and / or an alloy shielding layer. 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.

[0086] The embodiment of the present invention does not specifically limit the thickness of the second shielding layer 160, and can be appropriately set according to the conductive material used. Optionally, the thickness of the second shielding layer 160 ranges from 10 to 80 μm. The embodiment of the present invention sets the thickness of the second shielding layer 160 to range from 10 to 80 microns, which can make the thickness of the electromagnetic shielding cover moderate, while making the second shielding layer 160 have better shielding performance.

[0087] Fig. 9 is a flow chart of another method for preparing an electromagnetic shielding cover provided by an embodiment of the present invention, which is suitable for preparing Figure 8 Electromagnetic shielding, such as Fig. 9 As shown, the preparation method of the electromagnetic shielding cover includes:

[0088] S201, forming an insulating layer on the carrier layer.

[0089] S202 , sputtering a first metal layer on the first supporting layer to form a first shielding layer.

[0090] It should be noted that step S201 and step S202 are executed simultaneously.

[0091] S203, laminating the first shielding layer on the insulating layer, forming a second connecting layer on a side of the first shielding layer away from the insulating layer, and sputtering a second metal layer on the second supporting layer to form a second shielding layer.

[0092] S204 , pressing the second shielding layer onto a side of the second connecting layer away from the first shielding layer.

[0093] S205 , forming a first connecting layer on a side of the second shielding layer away from the insulating layer.

[0094] The first support layer has a first hollow portion, and the second support layer has a second hollow portion. The carrier layer is a release film that can be torn off and is only used during the preparation process and can be peeled off after the preparation is completed. Exemplarily, the material of the carrier layer can be polyester resin (Polyethylene terephthalate, PET).

[0095] Fig.10 FIG. 1 is a schematic cross-sectional structure diagram of another electromagnetic shielding cover provided by an embodiment of the present invention. Fig.10As shown, optionally, the second shielding layer 160 includes a second supporting layer 1601 and a second metal layer 1602, the second supporting layer 1601 is provided with a second hollow portion 16, and the second metal layer 1602 is arranged on at least one surface of the second supporting layer 1601 and the surface of the second hollow portion 16. Optionally, the first hollow portion 12 and the second hollow portion 16 are aligned one by one, and the first hollow portion 12 and the second hollow portion 16 have the same shape, so that the first connecting layer 130 passes through the second hollow portion 16 and the first hollow portion 12 in sequence to connect with the insulating layer 110.

[0096] The embodiment of the present invention does not specifically limit the material of the second support layer 1601. Exemplarily, the material of the second support layer 1601 may be a non-woven fabric. The embodiment of the present invention does not specifically limit the thickness of the second support layer 1601, and it may be appropriately set according to the support material used. Exemplarily, the thickness of the second support layer 1601 ranges from 5 μm to 20 μm. The second metal layer 1602 may be sputtered on the second support layer 1601 to make the second support layer 1601 conductive. According to actual needs, the second metal layer 1602 may be thickened by vacuum sputtering or electroplating to form the second shielding layer 160.

[0097] The second hollow portion 16 may be a square through hole or a through hole of any other shape. Fig.10 The second hollow portion 16 is a square through hole for illustration only. By providing a plurality of second hollow portions 16 in the second supporting layer 1202, the present invention can make the glue material of the first connection layer 130 and the second connection layer 150 be squeezed into the second hollow portions 16 when the electromagnetic shielding cover is pressed against the circuit board, thereby enhancing the bonding force between the electromagnetic shielding cover and the circuit board, and avoiding the electromagnetic shielding cover bubbling and delamination causing the electromagnetic shielding cover to peel off from the ground of the circuit board.

[0098] Based on the above embodiments, continue to refer to Fig.10 Optionally, the second connection layer 150 is provided with conductive particles 32, and the first shielding layer 120 and the second shielding layer 160 are electrically connected at least through the conductive particles 32. By setting the second connection layer 150 as an adhesive layer containing conductive particles 32, the conductivity of the second connection layer 150 can be improved, thereby further ensuring the ground connection between the electromagnetic shielding cover and the circuit board. Of course, the second connection layer 150 can also be an adhesive layer without conductive particles to reduce the insertion loss of the circuit board with the electromagnetic shielding cover, thereby improving the shielding effectiveness and the bending property of the circuit board.

[0099] Fig.11 FIG. 1 is a schematic cross-sectional structure diagram of another electromagnetic shielding cover provided by an embodiment of the present invention. Fig.11, one side of the first shielding layer 120 close to the second connecting layer 150 is a non-flat surface, and one side of the second shielding layer 160 close to the first connecting layer 130 is a non-flat surface. In an embodiment of the present invention, the non-flat surface is a regular non-flat surface or an irregular non-flat surface. Specifically, when the non-flat surface is a regular non-flat surface, the non-flat surface is a periodically undulating structure, and the amplitude of the undulation and the interval of the undulation on the non-flat surface are the same; when the non-flat surface is an irregular non-flat surface, the non-flat surface is a non-periodically undulating structure, and the amplitude of the undulation and / or the interval of the undulation on the non-flat surface are different. The non-flat surfaces of the first shielding layer 120 and the second shielding layer 160 can enhance the bonding force between the electromagnetic shielding cover and the circuit board, so that the electromagnetic shielding cover is not prone to blistering and delamination. In addition, when the electromagnetic shielding cover is pressed together with the circuit board, the glue material constituting the second connecting layer 150 is squeezed into the recessed position of the first shielding layer 120, and the glue material constituting the first connecting layer 130 is squeezed into the recessed position of the second shielding layer 160, so as to increase the glue capacity, thereby making it less likely for the board to explode. This avoids the problem of high-temperature explosion of the existing electromagnetic shielding cover due to insufficient glue capacity, thereby effectively ensuring that the electromagnetic shielding cover is grounded, thereby conducting out interference charges.

[0100] Continue to refer Fig.11 In order to make it easier for the second shielding layer 160 to pierce the second connection layer 150 during the pressing process, the second shielding layer 160 is easier to pierce the first connection layer 130 during the pressing process. In this embodiment, the first shielding layer 120 is provided with a first undulating portion 121 on a side away from the insulating layer 110, and the first undulating portion 121 is used to pierce the second connection layer 150. And / or, the second shielding layer 160 is provided with a second undulating portion 161 on a side away from the first shielding layer 120, and the second undulating portion 161 is used to pierce the first connection layer 130.

[0101] Specifically, the first undulating portion 121 and the second undulating portion 161 include a plurality of convex portions and a plurality of concave portions, and the plurality of convex portions and the plurality of concave portions are arranged at intervals. In order to further ensure the reliability of grounding and improve the conductive efficiency at the same time, the spacing between each convex portion and the adjacent concave portion in the embodiment of the present invention is the same. By setting the spacing between each convex portion and the adjacent concave portion to be the same, the plurality of convex portions can uniformly pierce the first connection layer 130 or the second connection layer 150, thereby further ensuring the reliability of the connection between the electromagnetic shielding cover and the grounding 100 of the circuit board, and improving the conductive efficiency at the same time.

[0102] Optionally, the shape of each convex part is the same; the shape of each concave part is the same; wherein each convex part is an axisymmetric structure; each concave part is an axisymmetric structure; of course, each convex part can also be a non-axisymmetric structure, and each concave part can also be a non-axisymmetric structure. Since the spacing between each convex part and the adjacent concave part is the same, and the shape of each convex part is the same, the shape of each concave part is the same, so that the amount of glue on the surface of the first shielding layer 120 and the second shielding layer 160 is relatively uniform, thereby further avoiding the explosion of the board, and further ensuring that the electromagnetic shielding cover is grounded, thereby exporting the interference charge.

[0103] Example 1

[0104] This embodiment provides an electromagnetic shielding cover, including an insulating layer 110. The average thickness of the insulating layer at any N points is is 10, the thickness standard deviation σ at N sampling points is 0.5, is equal to 0.95, It complies with the above formula 1.

[0105] Example 2

[0106] This embodiment provides an electromagnetic shielding cover, including an insulating layer 110. The average thickness of the insulating layer at any N points is is 5, the thickness standard deviation σ at N sampling points is 0.1, is equal to 0.98, that is It complies with the above formula 1.

[0107] Example 3

[0108] This embodiment provides an electromagnetic shielding cover, including an insulating layer 110. The average thickness of the insulating layer at any N points is is 15, the thickness standard deviation σ at N sampling points is 0, is equal to 1, that is It complies with the above formula 1.

[0109] Example 4

[0110] This embodiment provides an electromagnetic shielding cover, including an insulating layer 110. The average thickness of the insulating layer at any N points is 20, and the thickness standard deviation σ at the N sampling points is 0.2. is equal to 0.99, that is It complies with the above formula 1.

[0111] Comparative Example 1

[0112] This embodiment provides an electromagnetic shielding cover, including an insulating layer 110. The average thickness of the insulating layer at any N points is is 10, the thickness standard deviation σ at N sampling points is 5, is equal to 0.5, It does not conform to the above formula 1.

[0113] Comparative Example 2

[0114] This embodiment provides an electromagnetic shielding cover, including an insulating layer 110. The average thickness of the insulating layer at any N points is 5, and the thickness standard deviation σ at the N sampling points is 1. is equal to 0.8, It does not conform to the above formula 1.

[0115] The grounding resistance and shielding effectiveness at 5 GHz were measured using the above-mentioned embodiment and comparative test standards. The method for pressing the electromagnetic shielding cover to cover the circuit board is to press the electromagnetic shielding cover onto the FPC circuit board with components at room temperature using a pressure of 6 kg / cm, using a rectangular grounding window with a grounding area of ​​3 to 5 mm 2 , the maximum height of the sensor is 0.5-2mm, and the pressing is 10-50s. Detect the grounding resistance around the sensor, and the test results are shown in Table 1.

[0116] Table 1 Shielding performance and grounding resistance of electromagnetic shielding cover

[0117] Experimental subjects Shielding effectiveness(dB) Ground resistance (mOhm) Example 1 ≥70 234 Example 2 ≥75 166 Example 3 ≥75 356 Example 4 ≥75 129 Comparative Example 1 ≈60 729 Comparative Example 2 ≈55 855

[0118] From Table 1, we can see that when When the above formula 1 is met, the grounding resistance is small, the shielding effectiveness is greater than or equal to 70dB, and the reliability is high. When formula 1 is not satisfied, the grounding resistance is large and the shielding effectiveness is less than 65dB.

[0119] Based on the same inventive concept, an embodiment of the present invention further provides a circuit board, including the electromagnetic shielding cover provided by any of the above embodiments, having a corresponding electromagnetic shielding cover film layer structure and beneficial effects, and the similarities are not repeated here.

[0120] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An electromagnetic shielding cover, characterized in that: include: Insulating layer, the thickness of the insulating layer per unit area satisfies: in, is the average thickness of the insulating layer at any N points, σ ​​is the standard deviation of the thickness at N sampling points, and N≥3.

2. The electromagnetic shielding cover according to claim 1, characterized in that: The thickness of the insulating layer per unit area satisfies: Among them, d max is the maximum thickness at N sampling points, d min is the minimum thickness at N sampling points.

3. The electromagnetic shielding cover according to claim 1, characterized in that: In any 600 μm straight line measurement range, the maximum thickness difference between any two points of the insulating layer is less than 5 μm.

4. The electromagnetic shielding cover according to claim 1, characterized in that: The thickness of the insulating layer is in the range of 10 to 20 μm.

5. The electromagnetic shielding cover according to claim 1, characterized in that: It also includes a first shielding layer, wherein the insulating layer is disposed on a side surface of the first shielding layer; Within a unit area, the measured values ​​of the film surface resistance of the insulating layer at a side away from the first shielding layer differ in order of magnitude within 4 levels.

6. The electromagnetic shielding cover according to claim 5, characterized in that: Within a unit area, the measured values ​​of the film surface resistance of the insulating layer at a side away from the first shielding layer are of the same order of magnitude.

7. The electromagnetic shielding cover according to claim 5, characterized in that: The electromagnetic shielding cover further includes a first connection layer, which is disposed on a side of the first shielding layer away from the insulating layer, and the first connection layer is used for grounding to a circuit board.

8. The electromagnetic shielding cover according to claim 7, characterized in that: The electromagnetic shielding cover further includes a conductive layer, and the conductive layer is arranged on a side of the first shielding layer close to and / or away from the first connecting layer.

9. The electromagnetic shielding cover according to claim 7, characterized in that: The electromagnetic shielding cover also includes a second shielding layer and a second connecting layer. The second shielding layer and the second connecting layer are both arranged between the first shielding layer and the first connecting layer. The second shielding layer is connected to a side of the first shielding layer away from the insulating layer through the second connecting layer.

10. The electromagnetic shielding cover according to claim 9, characterized in that: Conductive particles are arranged in the first connection layer, and the first shielding layer is electrically connected to the ground of the circuit board at least through the conductive particles; and / or, Conductive particles are disposed in the second connection layer, and the first shielding layer and the second shielding layer are electrically connected at least through the conductive particles.

11. The electromagnetic shielding cover according to claim 5, characterized in that: A concave-convex portion is provided on a side surface of the insulating layer close to the first shielding layer, and the first shielding layer is arranged in contact with the concave-convex portion.

12. The electromagnetic shielding cover according to claim 8, characterized in that: The first shielding layer is provided with a plurality of first hollow portions, and the first shielding layer is made of conductive material.

13. The electromagnetic shielding cover according to claim 9, characterized in that: The thickness of the first shielding layer ranges from 10 to 80 μm; And / or, the thickness of the second shielding layer is in the range of 10 to 80 μm.

14. The electromagnetic shielding cover according to claim 9, characterized in that: The first shielding layer includes a first supporting layer and a first metal layer, the first supporting layer is provided with a first hollow portion, and the first metal layer is arranged on at least one surface of the first supporting layer and an inner wall of the first hollow portion; and / or, The second shielding layer includes a second supporting layer and a second metal layer. The second supporting layer is provided with a second hollow portion. The second metal layer is arranged on at least one surface of the second supporting layer and an inner wall of the second hollow portion.

15. A circuit board, characterized in that: The electromagnetic shielding cover comprises the electromagnetic shielding cover as claimed in any one of claims 1 to 14.

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