Electromagnetic shielding case and circuit board

Abstract

The invention discloses an electromagnetic shielding case and a circuit board, and the electromagnetic shielding case comprises a first shielding layer which is conductive; the first connecting layer is arranged on one side of the first shielding layer; and a plurality of first conductive particles, each first conductive particle is arranged in the first connecting layer, the maximum width range of each first conductive particle is 1 [mu] m-40 [mu] m, and the maximum widths of at least part of the first conductive particles are not equal. The first conductive particles with the smaller maximum width are small in protruding height at the bending position, the bending resistance is good, the first conductive particles with the larger maximum width are good in conductivity, and electric connection between the first shielding layer and the grounding layer on the circuit board located on the side, away from the first shielding layer, of the first connecting layer is easy to achieve. Therefore, the arrangement of the first conductive particles with different maximum widths can give consideration to both conductivity and offset resistance, so that the electromagnetic shielding case can extend between two adjacent electronic components for shielding, and the shielding effect is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic shielding, 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). The main function of an electromagnetic shield 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 an electromagnetic shield 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] Electromagnetic shielding covers are usually used in electronic devices, such as mobile phones, televisions, computers, etc., to protect internal circuits and components from external electromagnetic interference, and also prevent internal electromagnetic radiation from leaking into the external environment. However, existing circuit boards are often equipped with electronic components of different heights, which makes it very easy for the electromagnetic shielding cover to break when pressed on the circuit board due to the excessive height difference between the electronic components, and it is difficult to enter between adjacent electronic components with small spacing, resulting in poor shielding effect. Summary of the invention

[0004] The present invention provides an electromagnetic shielding cover and a circuit board, so as to improve the breaking resistance and bending performance of the electromagnetic shielding cover, thereby improving the shielding effect of the electromagnetic shielding cover.

[0005] According to one aspect of the present invention, there is provided an electromagnetic shielding cover, comprising:

[0006] a first shielding layer, the first shielding layer being conductive;

[0007] a first connecting layer, the first connecting layer being arranged on one side of the first shielding layer;

[0008] A plurality of first conductive particles are provided in the first connecting layer, each of the first conductive particles has a maximum width ranging from 1 μm to 40 μm, and at least some of the first conductive particles have unequal maximum widths.

[0009] Optionally, some of the first conductive particles are granular particles, and some of the first conductive particles are flake particles.

[0010] Optionally, the number of first conductive particles with a maximum width between 1 μm and 10 μm accounts for greater than or equal to 60%.

[0011] Optionally, the proportion of the first conductive particles with a maximum width between 10 μm and 15 μm is less than or equal to 40%.

[0012] Optionally, in the first connection layer, every 25 μm 2 The number of the first conductive particles is 1 to 50.

[0013] Optionally, the minimum distance between any of the first conductive particles and the first surface of the first connecting layer is less than or equal to 4 μm; and / or,

[0014] The minimum distance between any of the first conductive particles and the second surface of the first connecting layer is less than or equal to 4 μm;

[0015] The first surface of the first connection layer is a surface of the first connection layer close to the first shielding layer, and the second surface of the first connection layer is a surface of the first connection layer away from the first shielding layer.

[0016] Optionally, the electromagnetic shielding cover further includes an insulating layer, and the insulating layer is arranged on a side of the first shielding layer away from the first connecting layer.

[0017] The insulating layer includes a base layer and an adhesive layer, and the base layer is arranged on a side of the adhesive layer away from the first shielding layer.

[0018] Optionally, the electromagnetic shielding cover further includes a second shielding layer, and the second shielding layer is arranged between the first shielding layer and the first connecting layer.

[0019] Optionally, the electromagnetic shielding cover further includes a second connecting layer, and the second shielding layer is connected to a side of the first shielding layer close to the first connecting layer through the second connecting layer.

[0020] Optionally, the electromagnetic shield further comprises a plurality of second conductive particles, each of which is disposed in the second connecting layer, and the second shielding layer is electrically connected to the first shielding layer via at least one of the second conductive particles;

[0021] Some of the second conductive particles are granular particles, and some of the second conductive particles are flake particles.

[0022] The second shielding layer includes a second supporting layer and a second metal layer. The second supporting layer includes a plurality of second hollow portions. The second metal layer is formed on the surface of the second supporting layer and the inner wall of each of the second hollow portions.

[0023] Optionally, the first shielding layer includes a first supporting layer and a first metal layer, the first supporting layer includes a plurality of first hollow portions, and the first metal layer is formed on a surface of the first supporting layer and an inner wall of each of the first hollow portions.

[0024] According to another aspect of the present invention, a circuit board is provided, comprising the electromagnetic shielding cover as described in any one of the above.

[0025] According to the technical solution of the embodiment of the present invention, a plurality of first conductive particles are arranged in the first connection layer of the electromagnetic shielding cover, and the maximum width of each first conductive particle is within the range of 1 μm to 40 μm. The first conductive particles with a smaller maximum width have a smaller protrusion height at the bend and better bending resistance, and the first conductive particles with a larger maximum width have better conductivity, and are easy to realize the electrical connection between the first shielding layer and the grounding layer on the circuit board located on the side of the first connection layer away from the first shielding layer. Therefore, first conductive particles with different maximum widths are arranged, and the size range is limited. Under the synergistic effect, the conductivity and the resistance to breakage can be taken into account, so that the electromagnetic shielding cover can extend between two adjacent electronic components for shielding, thereby ensuring the shielding effect.

[0026] 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

[0027] 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.

[0028] Figure 1 A schematic diagram of the structure of an electromagnetic shielding cover provided in Embodiment 1 of the present invention;

[0029] Figure 2 A schematic diagram of the structure of an electromagnetic shielding cover provided in Embodiment 2 of the present invention;

[0030] Figure 3 This is a schematic structural diagram of an electromagnetic shielding cover provided in Embodiment 3 of the present invention. DETAILED DESCRIPTION

[0031] 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.

[0032] 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, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0033] Embodiment 1

[0034] Figure 1 This is a schematic diagram of the structure of an electromagnetic shielding cover provided in the first embodiment of the present invention, referring to Figure 1 , the electromagnetic shielding cover comprises:

[0035] A first shielding layer 10, the first shielding layer 10 is conductive;

[0036] A first connection layer 11, wherein the first connection layer 11 is disposed on one side of the first shielding layer 10;

[0037] A plurality of first conductive particles 111 are disposed in the first connection layer 11 , and the maximum width of each first conductive particle 111 ranges from 1 μm to 40 μm. At least some of the first conductive particles have different maximum widths.

[0038] The first connection layer 11 is a pressure-sensitive conductive adhesive or pressure-sensitive adhesive. Specifically, the pressure-sensitive conductive adhesive is composed of resin and conductive material, namely, first conductive particles 111, and has conductivity and adhesion. The first shielding layer 10 is connected to the circuit board through the first connection layer 11, so that the electromagnetic shielding cover as a whole can electromagnetically shield the components on the circuit board.

[0039] Optionally, the first shielding layer 10 can be a conductive non-woven fabric, a conductive nylon fabric, a conductive fabric, a conductive polymer, etc. Specifically, the first shielding layer is a conductive non-woven fabric. The first shielding layer 10 is conductive, and the conductive material in the first shielding layer 10 generates current under the action of an external electromagnetic field or an internal electromagnetic field, thereby offsetting the influence of the electromagnetic field on the internal circuits and components of the device, and preventing the electromagnetic radiation on the circuit board from leaking into the external environment. The first shielding layer 10 plays an electromagnetic shielding role, and the electromagnetic interference signal is guided out by grounding. The material of the first shielding layer 10 includes non-woven fabric, so that the electromagnetic shielding cover has a lower hardness, better ductility, and is resistant to stretching and bending. Optionally, the first shielding layer 10 includes a first supporting layer and a first metal layer, and the first supporting layer includes a plurality of first hollow portions, and the first metal layer is formed on at least one side surface of the first supporting layer and the inner wall of each first hollow portion. The first support layer may be a non-woven fabric layer. By forming metal on the surface of the non-woven fabric and the inner wall of the first hollow portion, the first shielding layer 10 is made conductive. The surface of the first support layer includes a surface of the first support layer away from the first connection layer 11 and a surface of the first support layer close to the first connection layer 11. The first support layer includes the first hollow portion, which can reduce the hardness of the first shielding layer 10 and prevent the first shielding layer 10 from breaking when bent. The first conductive particles 111 may be metal or non-metal. Furthermore, the hardness of the first conductive particles 111 is greater than the hardness of the non-woven fabric after the metal is sputtered to improve the grounding effect.

[0040] Optionally, the first conductive particles 111 may be in a shape of particles, flakes, strips or other shapes. Figure 1 FIG. 4 exemplarily shows that the first conductive particles 111 are all in granular form.

[0041] In one embodiment, the maximum width of each first conductive particle 111 is within 1 μm to 40 μm. The maximum width of the first conductive particle 111 is the maximum width of the cross-sectional shape of the first conductive particle 111 along the cross-sectional shape parallel to the thickness direction of the electromagnetic shield. The maximum width is the length between two points of the first conductive particle 111 with the largest straight-line distance on the above cross-sectional shape. Optionally, the maximum widths of the first set number of first conductive particles 111 are not equal, and the first set number can be 60% of the total amount of the first conductive particles 111. Preferably, the maximum widths of the first conductive particles 111 are different. If the maximum width of the first conductive particle 111 is too small, it is not conducive to connecting the first shielding layer 10 and the grounding layer on the circuit board respectively located on both sides of the first connecting layer 11 through the first conductive particle 111, resulting in poor conductivity of the first conductive particle 111. If the maximum width of the first conductive particle 111 is too large, it is very easy to accumulate at the bend, which can easily cause the electromagnetic shield to break. Therefore, the maximum width of the first conductive particles 111 needs to be set within a suitable range to improve the conductivity and the resistance to breakage, so that even if the height difference between components on the circuit board is large, the electromagnetic shielding cover is easy to bend and not easy to break when the electromagnetic shielding cover is pasted on the circuit board.

[0042] According to the technical solution of the embodiment of the present invention, a plurality of first conductive particles are arranged in the first connection layer of the electromagnetic shielding cover, and the maximum width of each first conductive particle is within the range of 1 μm to 40 μm. The first conductive particles with a smaller maximum width have a smaller protrusion height at the bend and better bending resistance, and the first conductive particles with a larger maximum width have better conductivity, and are easy to realize the electrical connection between the first shielding layer and the grounding layer on the circuit board located on the side of the first connection layer away from the first shielding layer. Therefore, first conductive particles with different maximum widths are arranged, and the size range is limited. Under the synergistic effect, the conductivity and the resistance to breakage can be taken into account, so that the electromagnetic shielding cover can extend between two adjacent electronic components for shielding, thereby ensuring the shielding effect.

[0043] Continue to refer Figure 1 Optionally, the number of first conductive particles 111 with a maximum width between 1 μm and 10 μm accounts for greater than or equal to 60%.

[0044] The number of first conductive particles with a maximum width between 1 μm and 10 μm is greater than or equal to 60% of the total number of first conductive particles 111. The number of first conductive particles 111 with a smaller maximum width is relatively large, so that when the electromagnetic shielding cover is bent, the first conductive particles 111 can be prevented from piling up at the bend, thereby improving the bending resistance of the electromagnetic shielding cover, and further improving the break resistance of the electromagnetic shielding cover.

[0045] Continue to refer Figure 1Optionally, the number of first conductive particles 111 with a maximum width between 10 μm and 15 μm accounts for less than or equal to 40%. That is, the number of first conductive particles 111 with a maximum width between 10 μm and 15 μm accounts for less than or equal to 40% of the total number of first conductive particles 111.

[0046] If the maximum width of the first conductive particles 111 is too large, they are easily accumulated at the bend when the electromagnetic shield is bent, and are very easy to break. Therefore, the number of the first conductive particles 111 with a larger maximum width is set to be smaller to avoid the accumulation of the first conductive particles 111 at the bend, improve the bending resistance of the electromagnetic shield, and further improve the fracture resistance of the electromagnetic shield.

[0047] Continue to refer Figure 1 , Optionally, in the first connection layer 111, every 25 μm 2 The number of the inner first conductive particles 111 is 1 to 50.

[0048] If every 25 μm 2 If the number of the first conductive particles 111 is less than 1 and the density of the first conductive particles 111 is low, the conductivity of the first connection layer 11 is poor, which is not conducive to the stable connection between the first shielding layer 10 and the grounding layer, resulting in poor shielding effect. 2 If the number of the first conductive particles 111 is greater than 50, the density of the first conductive particles 111 is too high, and the first conductive particles 111 are easily accumulated at the bends, resulting in a high hardness of the first connection layer 11 and a decrease in the fracture resistance performance. Therefore, the density of the first conductive particles 111 needs to be set within a reasonable range to take into account both the conductive performance and the fracture resistance performance.

[0049] Continue to refer Figure 1 Optionally, the minimum distance between any first conductive particle 111 and the first surface of the first connection layer 11 is greater than or equal to zero and less than or equal to 4 μm, or the minimum distance between any first conductive particle 111 and the second surface of the first connection layer 11 is greater than or equal to zero and less than or equal to 4 μm, or the minimum distance between any first conductive particle 111 and the first surface of the first connection layer 11 is greater than or equal to zero and less than or equal to 4 μm and the minimum distance between any first conductive particle 111 and the second surface of the first connection layer 11 is greater than or equal to zero and less than or equal to 4 μm. The first surface of the first connection layer 11 is the surface of the first connection layer 11 on the side close to the first shielding layer 10, and the second surface of the first connection layer 11 is the surface of the first connection layer 11 on the side away from the first shielding layer 10.

[0050] The minimum of the vertical distances between any point on the first conductive particle 111 and the first surface of the first connecting layer 11 is taken as the minimum distance between the first conductive particle 111 and the first surface of the first connecting layer 11. The minimum of the vertical distances between any point on the first conductive particle 111 and the second surface of the first connecting layer 11 is taken as the minimum distance between the first conductive particle 111 and the second surface of the first connecting layer 11. If the distance between the first conductive particle 111 and the first surface or the second surface of the first connecting layer 11 is too large, it is not conducive to connecting the first shielding layer 10 and the grounding layer on the circuit board. If the distance between the first conductive particle 111 and the first surface or the second surface of the first connecting layer 11 is too small, it is very easy to puncture the first connecting layer 11 or the first shielding layer 10 during the film layer lamination process, causing damage to the electromagnetic shielding cover. Therefore, the distance between the first conductive particle 111 and the first surface or the second surface needs to be set within an appropriate range.

[0051] Continue to refer Figure 1 Optionally, the electromagnetic shielding cover also includes an insulating layer 12, which is arranged on the side of the first shielding layer 10 away from the first connecting layer 11. Optionally, the insulating layer 12 includes a base layer 121 and an adhesive layer 122, and the base layer 121 is arranged on the side of the adhesive layer 122 away from the first shielding layer 10. The base layer 121 is made of film materials such as PI, and the base layer 121 supports the electromagnetic shielding film and ensures that the surface of the electromagnetic shielding film is smooth and easy to peel off. The adhesive layer 122 is made of epoxy resin, which ensures the insulation effect after cyclization and can provide bonding force with the first shielding layer 10 during lamination. Optionally, the electromagnetic shielding cover may also include a third connecting layer, which is arranged between the insulating layer 12 and the first shielding layer 10. The third connecting layer may not have conductivity but only adhesiveness, and the insulating layer 12 is connected to the side of the first shielding layer 10 away from the first connecting layer 11 through the third connecting layer.

[0052] Optionally, the plurality of first conductive particles include particles of a first particle size and particles of a second particle size, and at least one particle of a second particle size is disposed between two adjacent particles of the first particle size. The maximum width of the particles of the first particle size is greater than the maximum width of the particles of the second particle size. The maximum width of the particles of the first particle size is greater than 5 μm, and the maximum width of the particles of the second particle size is in the range of 1 μm to 3 μm. The first conductive particles with a larger maximum width and the first conductive particles with a smaller maximum width can be arranged at intervals to avoid the accumulation of the first conductive particles with a larger maximum width, resulting in poor bending resistance.

[0053] Embodiment 2

[0054] Figure 2 A schematic diagram of the structure of an electromagnetic shielding cover provided in the second embodiment of the present invention, referring to Figure 2 , the electromagnetic shielding cover comprises:

[0055] A first shielding layer 10, the first shielding layer 10 is conductive;

[0056] A first connection layer 11, wherein the first connection layer 11 is disposed on one side of the first shielding layer 10;

[0057] A plurality of first conductive particles 111 are disposed in the first connection layer. The maximum width of each first conductive particle 111 ranges from 1 μm to 40 μm, and at least some of the first conductive particles have different maximum widths.

[0058] The insulating layer 12 is disposed on a side of the first shielding layer 10 away from the first connecting layer 11. Optionally, the insulating layer 12 includes a base layer 121 and an adhesive layer 122, and the base layer 121 is disposed on a side of the adhesive layer 122 away from the first shielding layer 10.

[0059] Continue to refer Figure 1 Optionally, among the plurality of first conductive particles 111 , some of the first conductive particles 111 are granular particles, and some of the first conductive particles 111 are flake particles.

[0060] The granular first conductive particles 111 are of irregular shapes, which are not specifically limited.

[0061] The first connection layer 11 also includes sheet-shaped first conductive particles 111, which can further improve the conductive performance, and the sheet-shaped structure is easy to bend, which is beneficial to improving the bending resistance of the first connection layer 11. At the same time, the sheet-shaped first conductive particles 111 also have a certain shielding effect, so that the first connection layer 11 also has electromagnetic shielding performance, thereby improving the electromagnetic shielding effect of the electromagnetic shielding cover.

[0062] Optionally, the first shielding layer 10 includes a first supporting layer and a first metal layer, the first supporting layer includes a plurality of first hollow portions, and the first metal layer is formed on the surface of the first supporting layer and the inner wall of each first hollow portion.

[0063] Optional, every 25μm 2 The number of the first conductive particles is 1 to 50.

[0064] Optionally, the number of first conductive particles 111 with a maximum width between 1 μm and 10 μm accounts for greater than or equal to 60%.

[0065] Optionally, the proportion of the first conductive particles with a maximum width between 10 μm and 15 μm is less than or equal to 40%.

[0066] Optionally, the minimum distance between any first conductive particle 111, whether it is a granular first conductive particle 111 or a flaky first conductive particle 111, and the first surface of the first connecting layer 11 is less than or equal to 4 μm, or, the minimum distance between any first conductive particle 111, whether it is a granular first conductive particle 111 or a flaky first conductive particle 111, and the second surface of the first connecting layer 11 is less than or equal to 4 μm, or, the minimum distance between any first conductive particle 111 and the first surface of the first connecting layer 11 is less than or equal to 4 μm and the minimum distance between any first conductive particle 111 and the second surface of the first connecting layer 11 is less than or equal to 4 μm.

[0067] Optionally, the plurality of first conductive particles include particles of a first particle size and particles of a second particle size, and at least one particle of the second particle size is disposed between two adjacent particles of the first particle size. The maximum width of the particles of the first particle size is greater than the maximum width of the particles of the second particle size. The maximum width of the particles of the first particle size is greater than 5 μm, and the maximum width of the particles of the second particle size is in the range of 1 μm to 3 μm.

[0068] Optionally, the electromagnetic shielding cover further includes a second shielding layer 13, and the second shielding layer 13 is arranged between the first shielding layer 10 and the first connecting layer 11. Alternatively, the electromagnetic shielding cover further includes a third shielding layer, and the third shielding layer is arranged on a side of the first shielding layer 10 away from the first connecting layer 11. Alternatively, the electromagnetic shielding cover includes both the second shielding layer 13 and the third shielding layer, and the second shielding layer 13 is arranged between the first shielding layer 10 and the first connecting layer 11, and the third shielding layer is arranged on a side of the first shielding layer 10 away from the first connecting layer 11. In this embodiment, only the second shielding layer 13 is included as an example.

[0069] Providing an additional shielding layer on the basis of the first shielding layer 10 is equivalent to increasing the thickness of the first shielding layer 10, which is beneficial to improving the electromagnetic shielding effect.

[0070] Optionally, the second shielding layer 13 is made of conductive material. For example, the second shielding layer 13 can be a metal layer such as a copper metal layer, or other non-metallic conductive film layer. The second shielding layer 13 is a metal layer, which can reduce the resistance when the first shielding layer is connected to the ground layer on the circuit board, and can further improve the electromagnetic shielding effect.

[0071] Optionally, the electromagnetic shielding cover further includes a second connection layer 14 , and the second shielding layer 13 is connected to a side of the first shielding layer 10 close to the first connection layer 11 through the second connection layer 14 .

[0072] The second connection layer 14 is disposed between the first shielding layer 10 and the second shielding layer 13 . The second connection layer 14 may be a pressure-sensitive conductive adhesive layer, which is made of resin and conductive material and has conductivity and adhesion.

[0073] Optionally, the electromagnetic shield further includes a plurality of second conductive particles 141 , each of which is disposed in the second connecting layer 14 , and the second shielding layer 14 is electrically connected to the first shielding layer 10 via at least one second conductive particle 141 .

[0074] Optionally, some of the second conductive particles 141 are granular particles, and some of the second conductive particles 141 are flake particles.

[0075] Optional, every 25μm 2 The number of the second conductive particles is 1 to 50.

[0076] Optionally, the number of the second conductive particles 141 with a maximum width between 1 μm and 10 μm accounts for greater than or equal to 60%.

[0077] Optionally, the number of the second conductive particles 141 with a maximum width between 10 μm and 15 μm accounts for less than or equal to 40%.

[0078] The minimum distance between any second conductive particle 141 and the first surface of the second connection layer 14 is greater than or equal to zero and less than or equal to 4 μm, or the minimum distance between any second conductive particle 141 and the second surface of the second connection layer 14 is greater than or equal to zero and less than or equal to 4 μm, or the minimum distance between any second conductive particle 141 and the first surface of the second connection layer 14 is greater than or equal to zero and less than or equal to 4 μm and the minimum distance between any second conductive particle 141 and the second surface of the second connection layer 14 is greater than or equal to zero and less than or equal to 4 μm. The first surface of the second connection layer 14 is the surface of the second connection layer close to the first shielding layer 10, and the second surface of the second connection layer 14 is the surface of the second connection layer far from the first shielding layer 10.

[0079] In this embodiment, a second connecting layer is provided, but in other embodiments, the second connecting layer may not be provided, and the metal layer on the non-woven fabric in the first shielding layer, namely the first metal layer, is thickened by electroplating, evaporation plating, magnetron sputtering, etc.

[0080] Embodiment 3

[0081] Figure 3 This is a schematic diagram of the structure of an electromagnetic shielding cover provided by Embodiment 3 of the present invention, referring to Figure 3 , the electromagnetic shielding cover comprises:

[0082] A first shielding layer 10, the first shielding layer 10 is conductive;

[0083] A first connection layer 11, wherein the first connection layer 11 is disposed on one side of the first shielding layer 10;

[0084] A plurality of first conductive particles 111 are disposed in the first connection layer. The maximum width of each first conductive particle 111 ranges from 1 μm to 40 μm, and at least some of the first conductive particles have different maximum widths.

[0085] The insulating layer 12 is disposed on a side of the first shielding layer 10 away from the first connecting layer 11. Optionally, the insulating layer 12 includes a base layer 121 and an adhesive layer 122, and the base layer 121 is disposed on a side of the adhesive layer 122 away from the first shielding layer 10.

[0086] Continue to refer Figure 1 Optionally, among the plurality of first conductive particles 111 , some of the first conductive particles 111 are granular particles, and some of the first conductive particles 111 are flake particles.

[0087] Optionally, the first shielding layer 10 includes a first supporting layer and a first metal layer, the first supporting layer includes a plurality of first hollow portions, and the first metal layer is formed on the surface of the first supporting layer and the inner wall of each first hollow portion. The first conductive particles 111 may be metal or non-metal, and the hardness of the first conductive particles 111 is greater than the hardness of the non-woven fabric after metal sputtering, so as to improve the grounding effect.

[0088] Optional, every 25μm 2 The number of the first conductive particles is 10 to 50.

[0089] Optionally, the number of first conductive particles 111 with a maximum width between 1 μm and 10 μm accounts for greater than or equal to 60%.

[0090] Optionally, the number of first conductive particles 111 with a maximum width between 10 μm and 15 μm accounts for less than or equal to 40%.

[0091] Optionally, the minimum distance between any first conductive particle 111 and the first surface of the first connecting layer 11 is greater than or equal to zero and less than or equal to 4 μm, or, the minimum distance between any first conductive particle 111 and the second surface of the first connecting layer 11 is greater than or equal to zero and less than or equal to 4 μm, or, the minimum distance between any first conductive particle 111 and the first surface of the first connecting layer 11 is greater than or equal to zero and less than or equal to 4 μm, and the minimum distance between any first conductive particle 111 and the second surface of the first connecting layer 11 is greater than or equal to zero and less than or equal to 4 μm.

[0092] Optionally, the plurality of first conductive particles include particles of a first particle size and particles of a second particle size, and at least one particle of the second particle size is disposed between two adjacent particles of the first particle size. The maximum width of the particles of the first particle size is greater than the maximum width of the particles of the second particle size. The maximum width of the particles of the first particle size is greater than 5 μm, and the maximum width of the particles of the second particle size is in the range of 1 μm to 3 μm.

[0093] Optionally, the electromagnetic shielding cover further includes a second shielding layer 13, and the second shielding layer 13 is arranged between the first shielding layer 10 and the first connecting layer 11. Alternatively, the electromagnetic shielding cover further includes a third shielding layer, and the third shielding layer is arranged on a side of the first shielding layer 10 away from the first connecting layer 11. Alternatively, the electromagnetic shielding cover includes both the second shielding layer 13 and the third shielding layer, and the second shielding layer 13 is arranged between the first shielding layer 10 and the first connecting layer 11, and the third shielding layer is arranged on a side of the first shielding layer 10 away from the first connecting layer 11. In this embodiment, only the second shielding layer 13 is included as an example.

[0094] Providing an additional shielding layer on the basis of the first shielding layer 10 is equivalent to increasing the thickness of the first shielding layer 10, which is beneficial to improving the electromagnetic shielding effect.

[0095] Optionally, the second shielding layer 13 is a metallized non-woven fabric layer. Optionally, the second shielding layer 13 includes a second supporting layer and a second metal layer, the second supporting layer includes a plurality of second hollow portions, and the second metal layer is formed on the surface of the second supporting layer and the inner wall of each second hollow portion;

[0096] The second supporting layer includes non-woven fabric, and the second shielding layer 13 is a metalized non-woven fabric layer with the same structure as the first shielding layer 10, which can further reduce the hardness of the electromagnetic shielding cover and make the electromagnetic shielding cover resistant to bending. The second metal layer can be a metal layer such as a copper metal layer, or other non-metallic conductive film layer.

[0097] Optionally, the electromagnetic shield further includes a second connection layer 14, and the second shielding layer 13 is connected to a side of the first shielding layer 10 close to the first connection layer 11 through the second connection layer 14. The second connection layer 14 is located between the first shielding layer 10 and the second shielding layer 13.

[0098] Optionally, the electromagnetic shield further includes a plurality of second conductive particles 141 , each of which is disposed in the second connecting layer 14 , and the second shielding layer 14 is electrically connected to the first shielding layer 10 via at least one second conductive particle 141 .

[0099] Optionally, some of the second conductive particles 141 are granular particles, and some of the second conductive particles 141 are flake particles.

[0100] Optional, every 25μm 2The number of the second conductive particles is 1 to 50.

[0101] Optionally, the number of the second conductive particles 141 with a maximum width between 1 μm and 10 μm accounts for greater than or equal to 60%.

[0102] Optionally, the number of the second conductive particles 141 with a maximum width between 10 μm and 15 μm accounts for less than or equal to 40%.

[0103] The minimum distance between any second conductive particle 141 and the first surface of the second connecting layer 14 is greater than or equal to zero and less than or equal to 4 μm, or, the minimum distance between any second conductive particle 141 and the second surface of the second connecting layer 14 is greater than or equal to zero and less than or equal to 4 μm, or, the minimum distance between any second conductive particle 141 and the first surface of the second connecting layer 14 is greater than or equal to zero and less than or equal to 4 μm and the minimum distance between any second conductive particle 141 and the second surface of the second connecting layer 14 is greater than or equal to zero and less than or equal to 4 μm.

[0104] Embodiment 4

[0105] An embodiment of the present invention further provides a circuit board, comprising the electromagnetic shielding cover in any of the above embodiments. The beneficial effects of the circuit board are the same as those of the electromagnetic shielding cover, which will not be described in detail herein.

[0106] Embodiment 5

[0107] The present embodiment provides an electromagnetic shielding cover, which includes a first shielding layer and a first connecting layer and a plurality of first conductive particles arranged in the first connecting layer. Among the plurality of first conductive particles, the maximum width of some first conductive particles is 5μm, the maximum width of the first conductive particles of another part is 14μm, and the number of first conductive particles with a maximum width between 1μm and 10μm accounts for 60%, and the number of first conductive particles with a maximum width between 10μm and 15μm accounts for 20%. The grounding resistance of the electromagnetic shielding cover is 60mΩ, and the shielding effectiveness is 64dB when the electromagnetic shielding cover is used to electromagnetically shield the circuit board.

[0108] Embodiment 6

[0109] Different from the fifth embodiment, in this embodiment, the maximum width of most of the first conductive particles is 8 μm, and the number of first conductive particles with a maximum width between 1 μm and 10 μm accounts for 80%, and the number of first conductive particles with a maximum width between 10 μm and 15 μm accounts for 10%. The grounding resistance of the electromagnetic shielding cover in this embodiment is 45 mΩ, and the shielding effectiveness of the electromagnetic shielding cover for electromagnetic shielding of the circuit board is 63 dB.

[0110] Embodiment 7

[0111] Different from the fifth embodiment, in this embodiment, the maximum width of most of the first conductive particles is 6 μm, and the number of first conductive particles with a maximum width between 1 μm and 10 μm accounts for 60%, and the number of first conductive particles with a maximum width between 10 μm and 15 μm accounts for 30%. The grounding resistance of the electromagnetic shielding cover in this embodiment is 80 mΩ, and the shielding effectiveness of the electromagnetic shielding cover for electromagnetic shielding of the circuit board is 74 dB.

[0112] Comparative Example 1

[0113] The electromagnetic shielding cover of this embodiment includes a first shielding layer and a first connecting layer and a plurality of first conductive particles arranged in the first connecting layer. The maximum width of most of the first conductive particles is 50 μm, and the proportion of the first conductive particles with a maximum width greater than or equal to 50 μm is greater than or equal to 80%. The grounding resistance of the electromagnetic shielding cover in this embodiment is 250 mΩ, and the shielding effectiveness of the electromagnetic shielding cover when the circuit board is electromagnetically shielded is 47 dB.

[0114] Comparative Example 2

[0115] The difference from comparative example 1 is that the maximum width of most first conductive particles is 70 μm, and the proportion of first conductive particles with a maximum width greater than or equal to 60 μm is greater than or equal to 90%. The grounding resistance of the electromagnetic shielding cover in this embodiment is 270 mΩ, and the shielding effectiveness of the electromagnetic shielding cover for electromagnetic shielding of the circuit board is 52 dB.

[0116] Comparative Example 3

[0117] The difference from comparative example 1 is that the maximum width of most first conductive particles is 8 μm, and the number of first conductive particles with a maximum width between 1 μm and 10 μm accounts for 45%. The grounding resistance of the electromagnetic shielding cover in this embodiment is 210 mΩ, and the shielding effectiveness of the electromagnetic shielding cover for electromagnetic shielding of the circuit board is 45 dB.

[0118] In Examples 5 to 7, when the maximum width of the first conductive particles is between 1 μm and 40 μm, and the number of first conductive particles with a maximum width between 1 μm and 10 μm accounts for more than or equal to 60%, and the number of first conductive particles with a maximum width between 10 μm and 15 μm accounts for less than or equal to 40%, the grounding resistance of the electromagnetic shielding cover is less than 100 mΩ and the shielding effectiveness is greater than 60 dB. In Comparative Examples 1 and 2, the maximum width of the first conductive particles is between 50 and 70 μm, the grounding resistance is greater than 200 mΩ, and the shielding effectiveness is greater than 60 dB. In Comparative Example 3, the number of first conductive particles with a maximum width between 1 μm and 10 μm accounts for less than 60%, at which time the grounding resistance is greater than 200 mΩ and the shielding effectiveness is greater than 60 dB. It can be seen that the size and range of the maximum width of the first conductive particles in the electromagnetic shielding cover in this embodiment can make the grounding resistance of the electromagnetic shielding cover smaller and the shielding effectiveness higher.

[0119] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[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: a first shielding layer, the first shielding layer being conductive; a first connecting layer, the first connecting layer being arranged on one side of the first shielding layer; A plurality of first conductive particles are provided in the first connecting layer, each of the first conductive particles has a maximum width ranging from 1 μm to 40 μm, and at least some of the first conductive particles have unequal maximum widths.

2. The electromagnetic shielding cover according to claim 1, characterized in that: Some of the first conductive particles are granular particles, and some of the first conductive particles are flake particles.

3. The electromagnetic shielding cover according to any one of claims 1 or 2, characterized in that: The number of first conductive particles with a maximum width between 1 μm and 10 μm accounts for greater than or equal to 60%.

4. The electromagnetic shielding cover according to any one of claims 1 or 2, characterized in that: The number of first conductive particles with a maximum width between 10 μm and 15 μm accounts for less than or equal to 40%.

5. The electromagnetic shielding cover according to any one of claims 1 or 2, characterized in that: In the first connection layer, every 25 μm 2 The number of the first conductive particles is 1 to 50.

6. The electromagnetic shielding cover according to any one of claims 1 or 2, characterized in that: The minimum distance between any of the first conductive particles and the first surface of the first connecting layer is less than or equal to 4 μm; and / or, The minimum distance between any of the first conductive particles and the second surface of the first connecting layer is less than or equal to 4 μm; The first surface of the first connection layer is a surface of the first connection layer close to the first shielding layer, and the second surface of the first connection layer is a surface of the first connection layer away from the first shielding layer.

7. The electromagnetic shielding cover according to claim 1, characterized in that: The electromagnetic shielding cover further includes an insulating layer, and the insulating layer is arranged on a side of the first shielding layer away from the first connecting layer.

8. The electromagnetic shielding cover according to claim 7, characterized in that: The insulating layer includes a base layer and an adhesive layer, and the base layer is arranged on a side of the adhesive layer away from the first shielding layer.

9. The electromagnetic shielding cover according to claim 1, characterized in that: The electromagnetic shielding cover further includes a second shielding layer, which is arranged between the first shielding layer and the first connecting layer.

10. The electromagnetic shielding cover according to claim 9, characterized in that: The electromagnetic shielding cover further includes a second connecting layer, and the second shielding layer is connected to a side of the first shielding layer close to the first connecting layer through the second connecting layer.

11. The electromagnetic shielding cover according to claim 10, characterized in that: The electromagnetic shielding cover further includes a plurality of second conductive particles, each of which is disposed in the second connecting layer, and the second shielding layer is electrically connected to the first shielding layer via at least one of the second conductive particles.

12. The electromagnetic shielding cover according to claim 11, characterized in that: Some of the second conductive particles are granular particles, and some of the second conductive particles are flake particles.

13. The electromagnetic shielding cover according to claim 9, characterized in that: The second shielding layer includes a second supporting layer and a second metal layer. The second supporting layer includes a plurality of second hollow portions. The second metal layer is formed on the surface of the second supporting layer and the inner wall of each of the second hollow portions.

14. The electromagnetic shielding cover according to any one of claims 1, characterized in that: The first shielding layer includes a first supporting layer and a first metal layer. The first supporting layer includes a plurality of first hollow portions. The first metal layer is formed on the surface of the first supporting layer and the inner wall of each of the first hollow portions.

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

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