Electromagnetic shielding cover and circuit board

Abstract

The invention discloses an electromagnetic shielding case and a circuit board, the overall mechanical property of the electromagnetic shielding case is adjusted by limiting the elastic modulus E1 of an insulating layer and the elastic modulus E2 of the electromagnetic shielding case to meet the condition that E2-E1 / E2 is greater than or equal to 0.95 and less than 1, so that the insulating layer can play a role in supporting and protecting, the stress borne by the electromagnetic shielding case is reduced, and the service life of the electromagnetic shielding case is prolonged. Therefore, the electromagnetic interference between the components can be avoided in the device gap with a smaller gap, the conformal capability of the electromagnetic shielding cover to the circuit board is improved, and the shielding effect is improved.

Description

Technical Field

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

[0002] When in operation, the electronic components inside electronic devices will continuously emit useless electromagnetic wave signals, which will affect the normal operation of other adjacent electronic components and generate electromagnetic interference.

[0003] At present, an electromagnetic shielding cover including a metal shielding layer is usually used to cover the electronic device inside, so as to suppress the leakage of useless electromagnetic waves to the outside, and at the same time shield the external electromagnetic wave noise from interfering with the operation of the internal circuit. However, the current electromagnetic shielding cover is integrally covered on the components of the circuit board, and there will be electromagnetic interference between the components. The gaps between some adjacent components are small, so that the electromagnetic shielding cover cannot be inserted. In addition, in the use scenario with high steps, the shielding effect of the existing rigid electromagnetic shielding cover is poor, and the electromagnetic shielding effect is still insufficient. Summary of the invention

[0004] The invention provides an electromagnetic shielding cover and a circuit board, which improve the shielding effect.

[0005] In a first aspect, an embodiment of the present invention provides an electromagnetic shielding cover, comprising: an insulating layer and a first shielding layer stacked together, wherein an elastic modulus E1 of the insulating layer and an elastic modulus E2 of the electromagnetic shielding cover satisfy: 0.95≤|E2-E1| / E2<1.

[0006] Optionally, an elastic modulus E1 of the insulating layer and an elastic modulus E2 of the electromagnetic shielding cover satisfy 77≤|E2-E1|≤300.

[0007] Optionally, the transverse elastic modulus of the electromagnetic shield is 70-100 kgf / mm 2 and / or,

[0008] The longitudinal elastic modulus of the electromagnetic shield is 240-310 kgf / mm 2 and / or,

[0009] The elastic modulus of the insulating layer is 1.2 to 2.5 kgf / mm 2 .

[0010] Optionally, 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.

[0011] Optionally, the electromagnetic shielding cover further includes a first connecting layer, the first connecting layer is arranged on a surface of the first shielding layer away from the insulating layer, and the first shielding layer is provided with a plurality of first hollow portions.

[0012] Optionally, the electromagnetic shielding cover further includes a first conductive layer, and the first conductive layer is arranged between the first shielding layer and the first connecting layer.

[0013] Optionally, the electromagnetic shielding cover further includes a second connecting layer, and the second connecting layer is arranged between the first shielding layer and the first conductive layer.

[0014] Optionally, the electromagnetic shielding cover further includes a second shielding layer and a third connecting layer, the second shielding layer is arranged between the first shielding layer and the first connecting layer, and the third connecting layer is arranged between the first shielding layer and the second shielding layer.

[0015] Optionally, the electromagnetic shielding cover further includes an absorbing layer, which is disposed between the first shielding layer and the second shielding layer, the absorbing layer is electrically connected to the first shielding layer and the second shielding layer, and is used for absorbing electromagnetic waves.

[0016] Optionally, the first shielding layer includes a first supporting layer and a first metal layer, the first hollow portion is arranged in the first supporting layer, and the first metal layer covers at least one side surface of the first supporting layer and an inner wall of the first hollow portion; and / or,

[0017] The second shielding layer includes a second supporting layer, a second metal layer and a second hollow portion, wherein the second hollow portion is arranged in the second supporting layer, and the second metal layer covers at least one side surface of the second supporting layer and an inner wall of the second hollow portion.

[0018] Optionally, conductive particles are provided in the third connecting layer.

[0019] Optionally, the thickness of the first shielding layer and / or the second shielding layer is in the range of 10-50 μm.

[0020] In a second aspect, an embodiment of the present invention provides a circuit board, wherein the circuit board includes the electromagnetic shielding cover described in any embodiment of the present invention.

[0021] An embodiment of the present invention provides an electromagnetic shielding cover, which adjusts the overall mechanical properties of the electromagnetic shielding cover by limiting the elastic modulus E1 of the insulating layer and the elastic modulus E2 of the electromagnetic shielding cover to satisfy: 0.95≤|E2-E1| / E2<1, so that the insulating layer can play a supporting and protective role, thereby reducing the stress on the electromagnetic shielding cover, thereby avoiding electromagnetic interference between components in device gaps with small gaps, improving the conformal ability of the electromagnetic shielding cover to the circuit board, and improving the shielding effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram of the structure of an electromagnetic shielding cover is provided for an embodiment of the present invention;

[0023] Figure 2 A structural schematic diagram of an insulating layer is provided for an embodiment of the present invention;

[0024] Figure 3 A structural schematic diagram of an application of an insulating layer is provided for an embodiment of the present invention;

[0025] Figure 4 A structural schematic diagram of another electromagnetic shielding cover is provided for an embodiment of the present invention;

[0026] Figure 5 A structural schematic diagram of another electromagnetic shielding cover is provided for an embodiment of the present invention;

[0027] Figure 6 A structural schematic diagram of another electromagnetic shielding cover is provided for an embodiment of the present invention;

[0028] Figure 7 A structural schematic diagram of another electromagnetic shielding cover is provided for an embodiment of the present invention;

[0029] Figure 8 A structural schematic diagram of another electromagnetic shielding cover is provided for an embodiment of the present invention;

[0030] Fig. 9 A structural schematic diagram of another electromagnetic shielding cover is provided for an embodiment of the present invention;

[0031] Fig.10 A structural schematic diagram of another electromagnetic shielding cover is provided for an embodiment of the present invention;

[0032] Fig.11 A structural schematic diagram of another electromagnetic shielding cover is provided for an embodiment of the present invention;

[0033] Fig.12 A structural schematic diagram of another electromagnetic shielding cover is provided for an embodiment of the present invention;

[0034] Fig.13 A schematic structural diagram of another electromagnetic shielding cover is provided for an embodiment of the present invention. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution 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 part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] In the related art, the electromagnetic shielding cover is a metal shell structure, and the components installed on the circuit board are arranged under the metal shell to achieve electromagnetic shielding. However, this electromagnetic shielding cover cannot be bent and is only suitable for hard boards. With the development of lightweight and thin mobile terminals or other electronic devices, FPC circuit boards also need electromagnetic shielding, and the installation space of electromagnetic shielding covers is getting smaller and smaller. Therefore, electromagnetic shielding covers are developing towards flexibility. Compared with traditional metal shielding covers, flexible shielding covers have better flexibility and plasticity, and can better adapt to the shape and structure of components in the circuit board, improve shielding effect and heat dissipation efficiency. In use, the electromagnetic shielding cover is wrapped on an uneven circuit board, or the electromagnetic shielding cover is attached to electronic components of different heights and embedded in the gap between the components to reduce volume occupancy. However, due to the unevenness of the circuit board or the uneven height of the electronic components, when a high step difference or a high step appears on the attached surface, it is easy to have a gap between the electromagnetic shielding cover and the grounding layer during the pressing process of the electromagnetic shielding cover, resulting in an increase in the grounding resistance and thus affecting the electromagnetic shielding effect.

[0037] In view of this, an embodiment of the present invention provides an electromagnetic shielding cover, which can reduce the embedding ability of the electromagnetic shielding cover in small gaps at high step positions, improve the conformal effect of the electromagnetic shielding cover on the circuit board, reduce electromagnetic interference between adjacent components, and thus ensure a separate shielding effect.

[0038] Figure 1 A schematic diagram of the structure of an electromagnetic shielding cover is provided for an embodiment of the present invention. Figure 1 The insulating layer 130 and the first shielding layer 120 are stacked, and the elastic modulus E1 of the insulating layer 130 and the elastic modulus E2 of the electromagnetic shielding cover satisfy: 0.95≤|E2-E1| / E2<1.

[0039] Specifically, the electromagnetic shielding cover may include a first connection layer 110, a first shielding layer 120 and an insulating layer 130 which are stacked, wherein the electromagnetic shielding cover is connected to the circuit board through the first connection layer 110, wherein the first connection layer 110 may be a conductive material, such as a conductive glue, and in some embodiments, may also be a non-conductive colloid. The first shielding layer 120 has a conductive material, for example, the first shielding layer 120 may be a metal layer or a material layer with a conductive coating on the surface, and the first shielding layer 120 may play a role in electromagnetic shielding. The insulating layer 130 covers the surface of the first shielding layer 120, and the insulating layer 130 may be a resin material, such as an epoxy resin, an acrylic resin or a polyester resin.

[0040] When the electromagnetic shielding cover is attached to electronic components of different heights and embedded in the gap between the components, the stress on the first shielding layer 120 close to the components when it is bent is greater than the stress on the insulating layer 130 when it is bent. In order to improve this situation, the overall mechanical properties of the electromagnetic shielding cover are adjusted by defining the relationship between the elastic modulus E1 of the insulating layer 130 and the elastic modulus E2 of the electromagnetic shielding cover. Among them, the elastic modulus E1 of the insulating layer 130 and the elastic modulus E2 of the electromagnetic shielding cover satisfy: 0.95≤|E2-E1| / E2<1.

[0041] When the elastic modulus E1 of the insulating layer 130 is less than the elastic modulus E2 of the electromagnetic shielding cover, the relationship can be rewritten as 0<E1 / E2≤0.05, that is, the elastic modulus of the insulating layer 130 is much lower than the elastic modulus of the electromagnetic shielding cover. Since the stress of the first shielding layer 120 close to the device when it is bent is greater than the stress of the insulating layer 130 when it is bent, the insulating layer 130 is selected to have a smaller elastic modulus. When the external pressure or impact is applied, the insulating layer 130 can serve as a buffer layer to play a supporting and protective role, thereby reducing the stress borne by the electromagnetic shielding cover, thereby preventing the electromagnetic shielding cover from deformation or damage due to stress concentration, and the low elastic modulus of the insulating layer 130 makes it easier to achieve bonding and stacking with the first shielding layer 120 during the manufacturing process.

[0042] When the elastic modulus E1 of the insulating layer 130 is greater than the elastic modulus E2 of the electromagnetic shielding cover, the relationship can be rewritten as 1.95≤E1 / E2<2, that is, the elastic modulus of the insulating layer 130 is approximately twice the elastic modulus of the electromagnetic shielding cover. The insulating layer 130 provides a higher rigidity at this time. When the insulating layer 130 and the first shielding layer 120 are stacked, the better strength of the insulating layer can be used to indirectly improve the structural strength of the entire structure. When bending, the insulating layer 130 can better maintain the bending shape. When subjected to impact or vibration, the insulating layer 130 with a high elastic modulus can more effectively absorb and disperse energy, reduce the impact and vibration of the electromagnetic shielding cover, thereby helping to maintain the shape stability of the electromagnetic shielding cover under force and prevent it from breaking due to deformation.

[0043] An embodiment of the present invention provides an electromagnetic shielding cover, which adjusts the overall mechanical properties of the electromagnetic shielding cover by limiting the elastic modulus E1 of the insulating layer 130 and the elastic modulus E2 of the electromagnetic shielding cover to satisfy: 0.95≤|E2-E1| / E2<1, so that the insulating layer 130 can play a supporting and protective role, thereby reducing the stress on the electromagnetic shielding cover, thereby avoiding electromagnetic interference between components in device gaps with small gaps, improving the conformal ability of the electromagnetic shielding cover to the circuit board, and improving the shielding effect.

[0044] Optionally, the elastic modulus E1 of the insulating layer 130 and the elastic modulus E2 of the electromagnetic shielding cover satisfy 77≤|E2-E1|≤300. The difference between the elastic modulus E1 of the insulating layer 130 and the elastic modulus E2 of the electromagnetic shielding cover can make the various parts of the composite material deform synergistically when subjected to external forces, and the stress distribution is more uniform. It maintains good shape stability and mechanical properties when subjected to external forces such as tension and compression. This also helps to maintain the shielding effect of the electromagnetic shielding cover and prevent the shielding effectiveness from decreasing due to shape changes. Optionally, the elastic modulus E1 of the insulating layer 130 is 1.2 to 2.5 kgf / mm 2 The elastic modulus E2 of the electromagnetic shield is 78~310kgf / mm 2 .

[0045] Optionally, the transverse elastic modulus of the electromagnetic shield is 70 to 100 kgf / mm 2 This indicates that the electromagnetic shield can maintain good shape stability when subjected to lateral external forces and is not easily deformed, thereby ensuring the stability of electromagnetic shielding effectiveness. In some embodiments, the longitudinal elastic modulus of the electromagnetic shield is 240 to 310 kgf / mm 2, compared with the transverse elastic modulus, the longitudinal elastic modulus is higher, so the electromagnetic shielding cover can maintain good strength and toughness when subjected to tensile external force in the longitudinal direction, and is not easy to break. Therefore, on an uneven circuit board or between electronic components of different heights, the electromagnetic shielding cover can be bent in the longitudinal direction, utilizing the higher elastic modulus in the longitudinal direction to maintain good strength and toughness and not easy to break. In the transverse direction, the electromagnetic shielding cover can maintain good shape stability when subjected to lateral external forces and is not easy to deform, thereby ensuring the stability of the electromagnetic shielding effectiveness. Furthermore, the optimization of the longitudinal elastic modulus helps to make the transmission path of electromagnetic waves in the electromagnetic shielding cover more stable, reduce the scattering and reflection of electromagnetic waves, and thus improve the electromagnetic shielding effectiveness.

[0046] Optionally, the elastic modulus of the insulating layer 130 is 1.2 to 2.5 kgf / mm 2 The lower elastic modulus makes the insulating layer 130 more flexible. When subjected to external pressure or impact, the insulating layer 130 can act as a buffer layer to provide support and protection, thereby reducing the stress on the electromagnetic shielding cover, thereby preventing the electromagnetic shielding cover from being deformed or damaged due to stress concentration. The low elastic modulus of the insulating layer 130 makes it easier to achieve bonding and stacking with the first shielding layer 120 during the manufacturing process.

[0047] By limiting the difference in elastic modulus between the electromagnetic shielding cover and the insulating layer 130, the overall structure can maintain a good mechanical balance when subjected to external forces, avoiding stress concentration and excessive deformation. In addition, by adjusting the lateral and longitudinal elastic modulus of the electromagnetic shielding cover and the lower elastic modulus of the insulating layer 130, the electromagnetic shielding effectiveness of the overall structure is improved, ensuring that the circuit is protected from electromagnetic interference and electromagnetic leakage.

[0048] Optionally, the insulating layer 130 includes a base layer and an adhesive layer, wherein the base layer is disposed on a side of the adhesive layer away from the first shielding layer, wherein the base layer may be a film layer such as PI, which may play a supporting role and ensure that the surface of the insulating layer is smooth, so as to facilitate the peeling of the material on one side of the base layer. The adhesive layer may be a resin material, such as an acrylic resin or a polyester resin, etc. When the electromagnetic shielding cover made of the resin material is pressed together, the overall bonding force between the insulating layer 130 and the first shielding layer 120 may be enhanced.

[0049] Optional, Figure 2 A schematic diagram of the structure of an insulating layer is provided for an embodiment of the present invention, see Figure 2 The insulating layer 130 further includes filler particles 131 . The filler particles 131 are dispersed in the insulating layer 130 . The ratio of the spacing between two adjacent filler particles to the maximum width of the filler particles is greater than 1.2.

[0050] Specifically, the filler particles 131 are dispersed in the insulating layer 130 , and the filler particles 131 can support the insulating layer 130 , thereby increasing the mechanical strength of the insulating layer 130 to a certain extent without affecting its flexibility. The insulating layer 130 can protect the outer surface of the first shielding layer 120 .

[0051] The insulating layer 130 is mainly used for insulation to prevent the electromagnetic shielding cover from short circuiting. The filler particles 131 in the insulating layer 130 can also improve the performance indicators such as the electrical strength, dielectric constant and volume resistivity of the insulating material, thereby further enhancing the insulation effect of the insulating layer 130. And the filler particles 131 can also enhance the electromagnetic shielding effect to a certain extent. The filler particles 131 can change the electromagnetic properties of the insulating material, such as the dielectric constant and magnetic permeability, thereby affecting the propagation and attenuation of electromagnetic waves in the material. By selecting suitable filler particles 131, the electromagnetic shielding performance of the insulating layer 130 can be optimized so that it can be better applied in some scenarios. For example, the filler particles can be a granular filler composite material, such as silicate, carbonate, ceramic, graphite, rubber, carbon, quartz powder, talcum powder, asbestos powder, aluminum oxide, magnesium oxide, nano titanium oxide, nano silicon oxide, etc.

[0052] When the step height of the components on the circuit board is large, and there is a high step difference and a high step, for example, when the step height is in the range of 200μm to 3mm, the filler particles 131 of the insulating layer 130 are accumulated at the bend during the bending and attaching process of the electromagnetic shielding cover, thereby affecting the bending angle, and there will be a gap between the electromagnetic shielding cover and the circuit board, resulting in a smaller grounding area of ​​the electromagnetic shielding cover, and an increased grounding resistance that affects the shielding effect. In order to improve the bending performance of the insulating layer 130 at the bend, the spacing L between two adjacent filler particles 131 and the maximum width d of the filler particles 131 satisfy: L / d>1.2. The spacing L between two adjacent filler particles 131 is the minimum distance from the surface of the filler particle 131 to the surface of another filler particle 131, and the maximum width d of the filler particle 131 is the maximum width of two adjacent filler particles 131. In other words, the spacing between two adjacent filler particles 131 is at least 1.2 times the maximum width of the filler particle 131. Exemplarily, the mixing ratio of the glue and the conductive particles is adjusted to adjust the spacing between two adjacent filler particles 131. By selecting the maximum width of the filler particles 131, the relationship between the spacing L between two adjacent filler particles 131 and the maximum width d of the filler particles 131 in the embodiment of the present invention is satisfied. Figure 3 A schematic diagram of the structure of an insulating layer used in an embodiment of the present invention is provided, see Figure 3When the insulating layer 130 is bent, there can be sufficient space between two adjacent filler particles 131 for bending, avoiding the accumulation of filler particles 131 at the step after the electromagnetic shielding cover is pressed together, thereby reducing the gap 132 between the electromagnetic shielding cover and the circuit board, increasing the grounding area, reducing the grounding resistance, and improving the shielding effect.

[0053] Optionally, if the width of the filler particles 131 in the insulating layer 130 is too small, it cannot play a good supporting role. If the width is too large, the thickness of the film layer will increase, which is not conducive to miniaturization design. In the embodiment of the present invention, the maximum width of the filler particles 131 in the insulating layer 130 is in the range of 4-10 μm, for example, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm, which can support the insulating layer 130 and have a thinner film structure.

[0054] Compared with the prior art, in the embodiment of the present invention, by dispersing the filler particles 131 in the insulating layer 130, the spacing between two adjacent filler particles 131 is at least 1.2 times the maximum width of the filler particles 131. When the insulating layer 130 is bent, there can be sufficient space between two adjacent filler particles 131 for bending, thereby avoiding the accumulation of filler particles 131 at the step after the electromagnetic shielding cover is pressed together, thereby reducing the gap between the electromagnetic shielding cover and the circuit board, increasing the grounding area, reducing the grounding resistance, and improving the shielding effect.

[0055] Figure 4 A schematic diagram of the structure of another electromagnetic shielding cover is provided for an embodiment of the present invention, see Figure 4 The first shielding layer 120 is provided with a plurality of first hollow portions 121 .

[0056] Specifically, the first shielding layer 120 has a conductive material, and the electromagnetic interference signal of the first shielding layer 120 is guided out through the grounding point on the circuit board to play an electromagnetic shielding role. Exemplarily, the first shielding layer 120 can be made of a flexible conductive material, such as a conductive glue, a metal film, a conductive cloth, and a non-woven fabric coated with a metal layer. The first shielding layer 120 is provided with a plurality of first hollow portions 121, and the first hollow portions 121 penetrate the first shielding layer 120. The first connecting layer 110 can pass through the first shielding layer 120 and connect with the insulating layer 130 through the first hollow portions 121, so the bonding force provided by the first connecting layer 110 can be used to increase the bonding force between the first shielding layer 120 and the insulating layer 130. Among them, the shape of the first hollow portion 121 can be a quadrilateral, a polygon or a circle, and the first hollow portion 121 can provide a space for the first shielding layer 120 to pass through, and can also release the stress of the first shielding layer 120 when it is bent, further improving the bending performance of the first shielding layer 120. In some embodiments, the first shielding layer 120 may be made of a non-woven fabric coated with a metal layer, and the gap structure of the non-woven fabric itself may be used as the first hollow portion 121, thereby reducing the preparation process of the first hollow portion 121 and saving preparation costs.

[0057] Optionally, the first connection layer 110 may be provided with conductive particles 111. Specifically, a certain proportion of conductive particles 111 are filled in the first connection layer 110. The conductive particles 111 may be metal sheets, metal powders, metal fibers, etc. The first shielding layer 120, as a film layer adjacent to the first connection layer 110, may be grounded to the circuit board through the conductive particles 111, and the electromagnetic interference signal on the first shielding layer 120 may be derived by using the conductive particles 111.

[0058] As an optional embodiment, Figure 5 A schematic diagram of the structure of another electromagnetic shielding cover is provided for an embodiment of the present invention, see Figure 5 The surface of the first shielding layer 120 close to the first connecting layer 110 has a metal protrusion 112. The metal protrusion 112 can be generated into a needle-like protrusion through a magnetron sputtering process. When the electromagnetic shielding cover is pressed together, the metal protrusion 112 will squeeze and pierce the first connecting layer 110, thereby achieving the effect of grounding connection with the circuit board. The production cost is low and the shielding efficiency is high. At the same time, the attenuation of high-frequency signals can be greatly reduced. At this time, the first connecting layer 110 can use non-conductive glue.

[0059] Figure 6 A schematic diagram of the structure of another electromagnetic shielding cover is provided for an embodiment of the present invention, see Figure 6 The electromagnetic shielding cover further includes a first conductive layer 140 , which is disposed between the first shielding layer 120 and the first connecting layer 110 .

[0060] Specifically, the first conductive layer 140 may be a metal layer, wherein the metal material includes an alloy of one or more of copper, aluminum, stainless steel and silver. In order to improve the flexibility of the first conductive layer 140, the first conductive layer 140 may be formed on the surface of the first shielding layer 120 by vacuum sputtering, and the shielding effect of the electromagnetic shielding cover is further improved by thickening the metal layer of the first shielding layer 120. The thickness of the first conductive layer 140 in this embodiment may be set according to the actual shielding requirements, and is not limited here.

[0061] As an optional embodiment, Figure 7 A schematic diagram of the structure of another electromagnetic shielding cover is provided for an embodiment of the present invention, see Figure 7 The electromagnetic shielding cover also includes a second connection layer 150, which is arranged between the first shielding layer 120 and the first conductive layer 140. The second connection layer 150 is arranged between the first shielding layer 120 and the first conductive layer 140, that is, the first conductive layer 140 is combined with the first shielding layer 120 through the second connection layer 150, and the second connection layer 150 is used to improve the bonding force between the first shielding layer 120 and the first conductive layer 140, so as to avoid interlayer separation when the electromagnetic shielding cover is bent. Among them, the thickness of the second connection layer 150 can be less than the thickness of the first connection layer 110, and the second connection layer 150 can play a role of buffering between layers and improve the flexibility of the electromagnetic shielding cover. It should be noted that the materials of the second connection layer 150 and the first connection layer 110 here can be the same or different, and there is no limitation here. The first shielding layer 120 and the first conductive layer 140 form a double shielding layer. In a complex electromagnetic environment, the outer shielding layer can effectively absorb and shield external electromagnetic signals. The electromagnetic interference signal can further reduce the penetration ability of electromagnetic waves through multiple reflections and absorption in the double electromagnetic shielding layer, so that the energy of the electromagnetic waves that can ultimately penetrate the multi-layer shielding film is greatly reduced.

[0062] As an optional embodiment, Figure 8 A schematic diagram of the structure of another electromagnetic shielding cover is provided for an embodiment of the present invention, see Figure 8 The first connection layer 110 may be provided with conductive particles 111. Specifically, a certain proportion of conductive particles 111 may be filled in the first connection layer 110. The conductive particles 111 may be metal sheets, metal powders, metal fibers, etc. The first conductive layer 140 may be grounded to the circuit board through the conductive particles 111, and the electromagnetic interference signals on the first shielding layer 120 and the first conductive layer 140 may be derived by the conductive particles 111.

[0063] As an optional embodiment, continue to refer to Figure 8The second connection layer 150 may be provided with conductive particles 111. Specifically, a certain proportion of conductive particles 111 may be filled in the second connection layer 150. The conductive particles 111 may be metal sheets, metal powders, metal fibers, etc. The first conductive layer 140 may be connected to the second connection layer 150 through the conductive particles 111. The first shielding layer 120 may guide the electromagnetic interference signal through the second connection layer 150, the first conductive layer 140 and the first connection layer 110 to improve the shielding effect.

[0064] As an optional embodiment, the surface of the first conductive layer 140 close to the first connecting layer 110 has a metal protrusion 112. The metal protrusion 112 can be generated into a needle-like protrusion through a magnetron sputtering process. When the electromagnetic shielding cover is pressed together, the metal protrusion 112 will squeeze and pierce the first connecting layer 110, thereby achieving the effect of grounding connection with the circuit board. The production cost is low and the shielding efficiency is high. At the same time, the attenuation of high-frequency signals can be greatly reduced. At this time, the first connecting layer 110 can be without conductive particles 111 and non-conductive glue can be used.

[0065] Fig. 9 A schematic diagram of the structure of another electromagnetic shielding cover is provided for an embodiment of the present invention, see Fig. 9 The electromagnetic shielding cover also includes a second shielding layer 160 and a third connecting layer 151. The second shielding layer 160 is arranged between the first shielding layer 120 and the first connecting layer 110, and the third connecting layer 151 is arranged between the first shielding layer 120 and the second shielding layer 160. Specifically, the third connecting layer 151 is used to improve the bonding force between the first shielding layer 120 and the second shielding layer 160. The third connecting layer 151 and the first connecting layer 110 can be made of the same material, thereby reducing the types of production materials. The second shielding layer 160 has a conductive material, and the electromagnetic interference signal of the second shielding layer 160 is guided out through the grounding point on the circuit board to play an electromagnetic shielding role. Exemplarily, the second shielding layer 160 can be made of a flexible conductive material, such as conductive glue, metal film, conductive cloth, and non-woven fabric coated with a metal layer. Among them, the second shielding layer 160 can have the same structure as the first shielding layer 120. By setting up two layers of electromagnetic shielding layers, in a complex electromagnetic environment, the outer shielding layer can effectively absorb and shield external electromagnetic signals. The electromagnetic interference signal can be further reduced in the double-layer electromagnetic shielding layer through multiple reflections and absorption, so that the energy of the electromagnetic waves that can finally penetrate the multi-layer shielding film is greatly reduced.

[0066] As an optional embodiment, see Fig. 9The first connection layer 110 may be provided with conductive particles 111. Specifically, a certain proportion of the conductive particles 111 are filled in the first connection layer 110. The conductive particles 111 may be metal sheets, metal powders, metal fibers, etc. The second shielding layer 160 may be grounded to the circuit board through the conductive particles 111, and the electromagnetic interference signals on the second shielding layer 160 and the first shielding layer 120 may be derived by using the conductive particles 111.

[0067] As an optional embodiment, Fig.10 A schematic diagram of the structure of another electromagnetic shielding cover is provided for an embodiment of the present invention, see Fig.10 The third connection layer 151 may be provided with conductive particles 111. Specifically, a certain proportion of conductive particles 111 may be filled in the third connection layer 151. The conductive particles 111 may be metal sheets, metal powders, metal fibers, etc. The first shielding layer 120 may be connected to the second shielding layer 160 through the conductive particles 111, and the second shielding layer 160 may be grounded to the circuit board through the conductive particles 111. The conductive particles 111 are used to guide the electromagnetic interference signals on the second shielding layer 160 and the first shielding layer 120 to improve the shielding effect.

[0068] As an optional embodiment, Fig.11 A schematic diagram of the structure of another electromagnetic shielding cover is provided for an embodiment of the present invention, see Fig.11 The first shielding layer 120 is provided with a plurality of first hollow portions 121 , and the third connecting layer 151 is connected to the insulating layer 130 through the first hollow portions 121 .

[0069] The first shielding layer 120 is provided with a plurality of first hollow portions 121, and the first hollow portions 121 penetrate the first shielding layer 120. The second connection layer 151 can pass through the first shielding layer 120 and connect with the insulating layer 130 through the first hollow portions 121, so the bonding force provided by the third connection layer 151 can be used to increase the bonding force between the first shielding layer 120 and the insulating layer 130. The shape of the first hollow portion 121 can be a quadrilateral, a polygon or a circle, which provides a space for the first shielding layer 120 to pass through, and can also release the stress of the first shielding layer 120 when it is bent, further improving the bending performance of the first shielding layer 120. In some embodiments, the first shielding layer 120 can be a non-woven fabric coated with a metal layer, and the slit structure of the non-woven fabric itself is used as the first hollow portion 121, thereby reducing the preparation process of the first hollow portion 121 and saving the preparation cost.

[0070] In the embodiment of the present invention, the second shielding layer 160 is also provided with a plurality of second hollow portions 161, and the third connection layer 151 is connected to the first connection layer 110 through the second hollow portions 161. The second hollow portions 161 penetrate the second shielding layer 160, and the third connection layer 151 can pass through the second shielding layer 160 to connect to the first connection layer 110 through the second hollow portions 161, so the bonding force provided by the first connection layer 110 and the third connection layer 151 can be used to increase the bonding force between the second shielding layer 160 and the first connection layer 110. The shape of the second hollow portion 161 can be a quadrilateral, a polygon or a circle, which provides a space for the second shielding layer 160 to pass through, and can also release the stress of the second shielding layer 160 when it is bent, so as to further improve the bending performance of the second shielding layer 160. In some embodiments, the second shielding layer 160 can be a non-woven fabric coated with a metal layer, and the slit structure of the non-woven fabric itself is used as the second hollow portion 161, so as to reduce the preparation process of the first hollow portion 121 and save the preparation cost. It should be noted that the embodiment of the present invention exemplarily shows that the first shielding layer 120 and the second shielding layer 160 are both provided with corresponding hollow portions, while in some other embodiments, according to design requirements, only the first shielding layer 120 may have a plurality of first hollow portions 121, or only the second shielding layer 160 may have a plurality of second hollow portions 161. The embodiment of the present invention is only for illustration and is not specifically limited.

[0071] As an optional embodiment, the first connection layer 110 may be provided with conductive particles 111. Specifically, the first connection layer 110 is filled with a certain proportion of conductive particles 111, and the conductive particles 111 may be metal sheets, metal powders, metal fibers, etc. The second shielding layer 160, as a film layer adjacent to the first connection layer 110, may be grounded to the circuit board through the conductive particles 111, and the electromagnetic interference signal on the second shielding layer 160 may be derived by using the conductive particles 111.

[0072] As an optional embodiment, the second shielding layer 160 has a metal protrusion 112 on the surface close to the first connecting layer 110. The metal protrusion 112 can be generated into a needle-like protrusion through a magnetron sputtering process. When the electromagnetic shielding cover is pressed together, the metal protrusion 112 will squeeze and pierce the first connecting layer 110, thereby achieving the effect of grounding connection with the circuit board. The production cost is low and the shielding efficiency is high. At the same time, the attenuation of high-frequency signals can be greatly reduced. At this time, the first connecting layer 110 can use non-conductive glue.

[0073] As an optional embodiment, the third connection layer 151 is provided with conductive particles 111, and the first shielding layer 120 is electrically connected to the second shielding layer 160 through the conductive particles 111. In other words, the first shielding layer 120 is conductive with the second shielding layer 160, and the first shielding layer 120 can export the electromagnetic interference signal through the third connection layer 151, the second shielding layer 160 and the first connection layer 110, thereby improving the shielding effect.

[0074] As an optional embodiment, in order to ensure shielding requirements while avoiding the increase in cost and weight caused by excessive thickness of the shielding layer, the thickness range of the first shielding layer 120 and the second shielding layer 160 in the embodiment of the present invention is 10-50μm, for example, 10μm, 20μm, 30μm, 40μm or 50μm, etc.

[0075] As an optional embodiment, continue to refer to Fig.11 The first shielding layer 120 includes a first supporting layer 122, a first metal layer (not shown) and a first hollow portion 121, wherein the first hollow portion 121 is disposed in the first supporting layer 122, the first metal layer covers the surface of the first supporting layer 122 and the inner wall of the first hollow portion 121, and the third connecting layer 151 is connected to the insulating layer 130 through the first hollow portion 121

[0076] Specifically, the first support layer 122 is used as the main structure of the first shielding layer 120 to provide the overall frame of the first shielding layer 120. In order to meet the flexibility requirements, the first support layer 122 can be a non-woven fabric and an insulating woven fabric, etc. A first hollow portion 121 is provided in the first support layer 122, and the first hollow portion 121 penetrates the first support layer 122. The first metal layer is formed on the surface of the first support layer 122 and the inner wall of the first hollow portion 121 by vacuum sputtering, thereby forming a shielding layer with a shielding effect. The adjacent connecting layer can pass through the first shielding layer 120 and connect with the insulating layer 130 through the first hollow portion 121, so the bonding force provided by the first connecting layer 110 can be used to increase the bonding force between the first shielding layer 120 and the insulating layer 130. Among them, the shape of the first hollow portion 121 can be a quadrilateral, a polygon or a circle, which provides a space for the first shielding layer 120 to pass through, and can also release the stress of the first shielding layer 120 when it is bent, and further improve the bending performance of the first shielding layer 120. In some embodiments, the first shielding layer 120 may be made of a non-woven fabric coated with a metal layer, and the gap structure of the non-woven fabric itself may be used as the first hollow portion 121, thereby reducing the preparation process of the first hollow portion 121 and saving preparation costs.

[0077] As an optional embodiment, continue to refer to Fig.11Similarly, the second shielding layer 160 includes a second supporting layer 162, a second metal layer (not shown) and a second hollow portion 161. The second hollow portion 161 is arranged in the second supporting layer 162. The second metal layer covers the surface of the second supporting layer 162 and the inner wall of the second hollow portion 161. The third connecting layer 151 is connected to the first connecting layer 110 through the second hollow portion 161.

[0078] Specifically, the second supporting layer 162 serves as the main structure of the second shielding layer 160 and is used to provide the overall frame of the second shielding layer 160. In order to meet the flexibility requirements, the second supporting layer 162 may be a non-woven fabric, an insulating woven fabric, etc. A second hollow portion 161 is provided in the second supporting layer 162, and the second hollow portion 161 penetrates the second supporting layer 162. The second metal layer is formed on the surface of the second supporting layer 162 and the inner wall of the second hollow portion 161 by vacuum sputtering, thereby forming a shielding layer with a shielding effect. The adjacent first connecting layer 110 can pass through the second shielding layer 160 and connect to another film layer through the second hollow portion 161, so the bonding force provided by the first connecting layer 110 can be used to increase the bonding force. Among them, the shape of the second hollow portion 161 can be a quadrilateral, a polygon or a circle, which provides a space for the second shielding layer 160 to pass through, and can also release the stress of the second shielding layer 160 when it is bent, further improving the bending performance of the second shielding layer 160. In some embodiments, the second shielding layer 160 may be made of a non-woven fabric coated with a metal layer, and the gap structure of the non-woven fabric itself may be used as the second hollow portion 161, thereby reducing the preparation process of the second hollow portion 161 and saving preparation costs.

[0079] As an optional embodiment, Fig.12 A schematic diagram of the structure of another electromagnetic shielding cover is provided for an embodiment of the present invention, see Fig.12 The electromagnetic shielding cover further includes an absorbing layer 200 , which is disposed between the first shielding layer 120 and the second shielding layer 160 . The absorbing layer 200 is electrically connected to the first shielding layer 120 and the second shielding layer 160 , and is used for absorbing electromagnetic waves.

[0080] In this embodiment, the absorbing layer 200 includes a conductive material, so that the absorbing layer 200 is conductive, and the absorbing layer 200 is electrically connected to the first shielding layer 120 and the second shielding layer 160. Wherein, when a third connecting layer 151 is provided between the first shielding layer 120 and the second shielding layer 160, the absorbing layer 200 can be provided on the side of the third connecting layer 151 away from the second shielding layer 160, or on the side of the third connecting layer 151 close to the second shielding layer 160. The material of the absorbing layer 200 can be a pure metal layer, or an alloy material, or can be in the form of a polymer substrate + a metal alloy layer, which is not specifically limited in the embodiment of the present invention. It should be noted that when the absorbing layer 200 is in the form of a polymer substrate + a metal alloy layer, the metal alloy layer can be formed on two opposite surfaces of the polymer substrate, and the polymer substrate needs to be provided with a via hole, and the metal alloy layer also needs to be filled in the via hole and connect the metal alloy layers on the two opposite surfaces. Wherein, the structure with conductive properties (such as a pure metal layer or a metal alloy layer) in the absorbing layer 200 can be formed by magnetron sputtering. The absorbing layer 200 is magnetic and can absorb electromagnetic waves. When the electromagnetic shielding cover is used for electromagnetic shielding, on the one hand, the electromagnetic interference signal can be introduced into the ground layer through the shielding layer 100 and the absorbing layer 200; on the other hand, the absorbing layer 200 can absorb electromagnetic waves, further enhancing the shielding effect of the electromagnetic shielding cover. The absorbing layer 200 is at least sandwiched between two shielding layers 100, so that the electromagnetic waves entering from the shielding layers 100 on both sides can be absorbed by the absorbing layer 200, thereby improving the absorbing effect.

[0081] The electromagnetic shielding cover of this embodiment can, on the one hand, guide the electromagnetic interference signal to the ground through the second shielding layer 160 and the wave absorbing layer 200; on the other hand, the wave absorbing layer 200 can absorb electromagnetic waves, which can further enhance the shielding effect of the electromagnetic shielding cover. In addition, the wave absorbing layer 200 is disposed between the two shielding layers, so that the electromagnetic waves entering from the shielding layers on both sides can be absorbed by the wave absorbing layer, thereby improving the wave absorbing effect.

[0082] As an optional embodiment, Fig.13 A schematic diagram of the structure of another electromagnetic shielding cover is provided for an embodiment of the present invention, see Fig.13, at least one absorbing layer 200 is sandwiched between the first shielding layer 120 and the second shielding layer 160. Another absorbing layer 200 is disposed on the side of the first shielding layer 120 away from the second shielding layer 160, and the absorbing layer 200 is disposed between the first shielding layer 120 and the insulating layer 130. In another optional embodiment of the present invention, a absorbing layer 200 may be disposed on the side of the second shielding layer 160 away from the first shielding layer 120, and the absorbing layer 200 is disposed between the second shielding layer 160 and the first connecting layer 110. In some optional embodiments of the present invention, the electromagnetic shielding cover may also include at least one absorbing layer 200 sandwiched between the first shielding layer 120 and the second shielding layer 160, another absorbing layer 200 is disposed on the side of the first shielding layer 120 away from the second shielding layer 160, and a absorbing layer 200 may be disposed on the side of the second shielding layer 160 away from the first shielding layer 120.

[0083] In this embodiment, by arranging the absorbing layer 200 on the surface of the first shielding layer 120 and the second shielding layer 160, the absorbing layer 200 can be closer to the external working environment than the first shielding layer 120 and the second shielding layer 160, so that the electromagnetic waves from the external working environment entering the electromagnetic shielding cover can be at least partially absorbed by the absorbing layer 200 when entering the first shielding layer 120 or the second shielding layer 160. The absorbing layer 200 arranged between the first shielding layer 120 and the second shielding layer 160 further absorbs the electromagnetic waves, achieving a better absorbing effect, thereby further improving the shielding effect. Among them, the structure and material of the absorbing layer 200 at each position can be the same.

[0084] Optionally, the material of the absorbing layer 200 includes at least one element of Ni, P, Co, Mo, Cr, Mg, Si, Fe, O, N, Al, and Cu.

[0085] Furthermore, the mass percentage of Ni in the absorbing layer 200 is greater than or equal to 50% and less than or equal to 95%, and the mass percentage of Cr is greater than or equal to 5% and less than or equal to 30%.

[0086] Exemplarily, the mass percentage of Ni in the absorbing layer 200 is equal to 50%, 60%, 75%, 88% or 95%, and can also be any other percentage in the range of greater than or equal to 50% and less than or equal to 95%; the mass percentage of Cr is equal to 5%, 10%, 15%, 22% or 30%, and can also be any other percentage in the range of greater than or equal to 5% and less than or equal to 30%.

[0087] In an optional embodiment of the present invention, the absorbing layer 200 includes a nickel-chromium alloy.

[0088] Optionally, the wave absorbing layer 200 includes a polymer substrate and a metal alloy layer, wherein the polymer substrate has vias, and the metal alloy layer is disposed on the surface of the polymer substrate and in the vias; silicon is added to the polymer substrate. The polymer may be a polymer film such as PET, PVC, PP, PI, etc., and silicon may also be added to increase the magnetic permeability and enhance the magnetic properties of the alloy; to increase the magnetic saturation magnetic induction intensity of the material, thereby improving the magnetic properties and improving the hysteresis loss: silicon can improve the hysteresis loss of nickel-chromium alloy, so that the material exhibits a faster magnetization reaction and hysteresis effect when the external magnetic field changes, thereby improving the wave absorbing effect.

[0089] Optionally, the maximum thickness of the absorbing layer 200 is greater than or equal to 5 micrometers and less than or equal to 30 micrometers.

[0090] Optionally, the thickness of each position of the absorbing layer 200 may be equal, or the thickness of at least two positions of the absorbing layer 200 may be unequal. The maximum thickness of the absorbing layer 200 is the thickness corresponding to the position where the absorbing layer 200 has the maximum thickness. The thickness direction of the absorbing layer 200 is the same as the thickness direction y of the electromagnetic shielding cover. Exemplarily, the maximum thickness of the absorbing layer 200 may be equal to 5 microns, 10 microns, 15 microns, 21 microns, 25 microns or 30 microns.

[0091] By setting the maximum thickness of the absorbing layer 200 to be greater than or equal to 5 microns and less than or equal to 30 microns, on the one hand, the thickness of the absorbing layer 200 can be prevented from being too thick, thereby ensuring that the thickness of the electromagnetic shielding cover is not too thick, so that the electromagnetic shielding cover can be applied to a shielded structure (such as a circuit board) with high requirements for lightness and thinness; on the other hand, the absorbing layer 200 can have a certain thickness, thereby ensuring the absorbing effect of the absorbing layer 200.

[0092] The embodiment of the present invention further provides a circuit board, the circuit board includes a printed circuit board and a PCB, etc., the circuit board has electronic components, and the electromagnetic shielding cover of any embodiment of the present invention is attached to the surface of the electronic components. Because it includes the electromagnetic shielding cover of any embodiment of the present invention, it has the same beneficial effects, which will not be repeated here.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An electromagnetic shielding cover, characterized in that: include: The insulating layer and the first shielding layer are stacked, and the elastic modulus E1 of the insulating layer and the elastic modulus E2 of the electromagnetic shielding cover satisfy the following relationship: 0.95≤|E2-E1| / E2<1.

2. The electromagnetic shielding cover according to claim 1, characterized in that: The elastic modulus E1 of the insulating layer and the elastic modulus E2 of the electromagnetic shielding cover satisfy 77≤|E2-E1|≤300.

3. The electromagnetic shielding cover according to claim 1, characterized in that: The transverse elastic modulus of the electromagnetic shield is 70-100 kgf / mm 2 and / or, The longitudinal elastic modulus of the electromagnetic shield is 240-310 kgf / mm 2 and / or, The elastic modulus of the insulating layer is 1.2 to 2.5 kgf / mm 2 .

4. The electromagnetic shielding cover according to claim 1, 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.

5. The electromagnetic shielding cover according to claim 1, characterized in that: It also includes a first connecting layer, which is arranged on a surface of the first shielding layer away from the insulating layer, and the first shielding layer is provided with a plurality of first hollow portions.

6. The electromagnetic shielding cover according to claim 5, characterized in that: The electromagnetic shielding cover further includes a first conductive layer, which is disposed between the first shielding layer and the first connecting layer.

7. The electromagnetic shielding cover according to claim 6, characterized in that: The electromagnetic shielding cover further includes a second connecting layer, and the second connecting layer is arranged between the first shielding layer and the first conductive layer.

8. The electromagnetic shielding cover according to claim 5, characterized in that: The electromagnetic shielding cover further includes a second shielding layer and a third connecting layer. The second shielding layer is arranged between the first shielding layer and the first connecting layer. The third connecting layer is arranged between the first shielding layer and the second shielding layer.

9. The electromagnetic shielding cover according to claim 8, characterized in that: The electromagnetic shielding cover further comprises a wave absorbing layer, which is disposed between the first shielding layer and the second shielding layer, is electrically connected to the first shielding layer and the second shielding layer, and is used for absorbing electromagnetic waves.

10. The electromagnetic shielding cover according to claim 8, characterized in that: The first shielding layer includes a first supporting layer and a first metal layer, the first hollow portion is arranged in the first supporting layer, and the first metal layer covers at least one side 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, a second metal layer and a second hollow portion, wherein the second hollow portion is arranged in the second supporting layer, and the second metal layer covers at least one side surface of the second supporting layer and an inner wall of the second hollow portion.

11. The electromagnetic shielding cover according to any one of claims 8 to 10, characterized in that: Conductive particles are arranged in the third connection layer.

12. The electromagnetic shielding cover according to claim 11, characterized in that: The thickness of the first shielding layer and / or the second shielding layer is in the range of 10-50 μm.

13. A circuit board, characterized in that: The circuit board comprises the electromagnetic shielding cover as described in any one of claims 1-12.

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