Electromagnetic shielding cover and circuit board

Abstract

The invention discloses an electromagnetic shielding cover and a circuit board. The electromagnetic shielding case includes: an insulating layer; wherein the gram weight of the insulating layer and the heat conductivity coefficient of the electromagnetic shielding cover meet the formula: K = A * f + B, wherein f is the gram weight of the insulating layer, and the unit is g / dm < 2 >; k is the heat conductivity coefficient of the electromagnetic shielding case, and the unit is W / (m.K); -180 < = A < =-200; 140 < = B < = 180, and the calculation is dimensionless. According to the embodiment of the invention, by limiting the relationship between the gram weight of the insulating layer and the heat conductivity coefficient of the electromagnetic shielding cover, the gram weight of the insulating layer can be adjusted according to specific requirements during design, so that the electromagnetic shielding cover with relatively good heat dissipation performance and relatively high shielding performance is obtained, and the electromagnetic shielding cover is suitable for heat dissipation and electromagnetic shielding of components.

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] An electromagnetic shield is a metal shell used for electromagnetic shielding, mainly used to reduce the impact of electromagnetic interference (EMI) and electromagnetic radiation (EMR). Its main function is to block or suppress electromagnetic waves within a specific spatial range to achieve the purpose of shielding interference, protecting electronic equipment and confidential communications. The principle of the 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. In addition, electromagnetic shielding covers are also widely used in military, medical, security and other fields, such as military equipment and facilities, medical imaging equipment, nuclear power plants and power substations. However, when the components on the circuit board are heated, the electromagnetic shielding covers cannot dissipate heat in time, thus affecting the normal operation of the internal circuits and components. Summary of the invention

[0004] The present invention provides an electromagnetic shielding cover and a circuit board, which ensure the shielding effect and improve the heat dissipation performance at the same time.

[0005] In a first aspect, an embodiment of the present invention provides an electromagnetic shielding cover, comprising: an insulating layer; wherein the gram weight of the insulating layer and the thermal conductivity of the electromagnetic shielding cover satisfy the following relationship:

[0006] K = A*f + B;

[0007] Wherein, f is the weight of the insulating layer, in g / dm 2 ; K is the thermal conductivity of the electromagnetic shielding cover, in units of W / (mK); -180≤A≤-200; 140≤B≤180, and the calculation is dimensionless.

[0008] Optionally, the thermal conductivity of the insulating layer is 15-55 W / (mK).

[0009] Optionally, the insulating layer includes a filling layer and filler particles, the filler particles are dispersed in the filling layer, and the thermal conductivity of the filler particles is at least 10 W / (mK) greater than the thermal conductivity of the filling layer.

[0010] Optionally, the electromagnetic shielding cover further includes a first shielding layer, which is disposed on a side of the insulating layer, and the thermal conductivity of the first shielding layer is at least 10 W / (mK) greater than that of the insulating layer.

[0011] Optionally, the electromagnetic shielding cover further includes a first connecting layer, which is arranged on a side of the first shielding layer away from the insulating layer, and a thermal conductivity of the first connecting layer is smaller than a thermal conductivity of the first shielding layer.

[0012] Optionally, the electromagnetic shielding cover further includes a first conductive layer, and the first conductive layer is arranged on a side of the first shielding layer close to and / or away from the insulating layer.

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

[0014] Optionally, the first shielding layer includes a first supporting layer and a first metal layer, the first supporting layer is provided with a first hollow portion, and the first metal layer covers a surface of the first supporting layer and an inner wall of the first hollow portion; and / or,

[0015] The second shielding layer includes a second supporting layer and a second metal layer. The second supporting layer is provided with a second hollow portion. The second metal layer covers the surface of the second supporting layer and the inner wall of the second hollow portion.

[0016] Optionally, conductive particles are provided in the first connecting layer and / or the second connecting layer.

[0017] Optionally, the thickness of the first shielding layer and the second shielding layer is in the range of 10-50 μm.

[0018] Optionally, the first shielding layer and / or the second shielding layer is a conductive non-woven fabric.

[0019] 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.

[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] By limiting the relationship between the grammage of the insulating layer and the thermal conductivity of the electromagnetic shielding cover, the embodiment of the present invention can adjust the grammage of the insulating layer according to specific needs during design, thereby obtaining an electromagnetic shielding cover with good heat dissipation performance and high shielding performance, which is suitable for heat dissipation and electromagnetic shielding of components. 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 another electromagnetic shielding cover is provided for an embodiment of the present invention;

[0024] Figure 3 A structural schematic diagram of another electromagnetic shielding cover 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 schematic structural diagram of another electromagnetic shielding cover is provided for an embodiment of the present invention. DETAILED DESCRIPTION

[0031] 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.

[0032] In the related art, the electromagnetic shielding cover is a metal shell structure, and the components on the circuit board need to be covered under the metal shell. However, the electromagnetic shielding cover with a metal shell structure cannot be bent and can only be installed on a hard board PCB. With the development of lightweight and thin mobile terminals or other electronic devices, the space available for the installation of the electromagnetic shielding cover is compressed. Therefore, the electromagnetic shielding cover begins to adopt a flexible form similar to the electromagnetic shielding film. The electromagnetic shielding cover is wrapped on the uneven circuit board, and the electromagnetic shielding cover is attached to electronic components of different heights. The electromagnetic shielding cover can be embedded in the gap between the components to reduce the volume occupied. The electromagnetic shielding cover covers the components on the attached surface. When the components generate a lot of heat, the electromagnetic shielding cover cannot dissipate the heat in time, thereby affecting the normal operation of the internal circuits and components. If the electromagnetic shielding cover is made thinner, the shielding effect cannot be guaranteed.

[0033] In view of this, an embodiment of the present invention provides an electromagnetic shielding cover to ensure the shielding effect and improve the heat dissipation performance at the same time.

[0034] Figure 1 A schematic diagram of the structure of an electromagnetic shielding cover is provided for an embodiment of the present invention. Figure 1 , including: an insulating layer; wherein the gram weight of the insulating layer and the thermal conductivity of the electromagnetic shielding cover satisfy:

[0035] K = A*f + B;

[0036] Where f is the weight of the insulation layer, in g / dm 2 ; K is the thermal conductivity of the electromagnetic shielding cover, the unit is W / (mK); -180≤A≤-200; 140≤B≤180, and the calculation is dimensionless.

[0037] Specifically, the electromagnetic shielding cover includes 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 acrylic resin or a polyester resin. Exemplarily, by measuring the time it takes for the electromagnetic shielding cover to heat up from 20°C to 80°C, the thermal conductivity of the electromagnetic shielding cover can be obtained. Among them, the starting value of the temperature rise can be selected according to the needs, which is an example here and is not a specific limitation. The temperature rise test of the electromagnetic shielding cover can be measured by a variety of methods, such as a hot wire method, a hot plate method, a heat flow meter method or a thermocouple method. The gram weight of the insulating layer usually refers to the mass of the insulating material per unit volume. The insulating layer is the part of the electromagnetic shielding cover used to prevent the passage of current, and sufficient gram weight must be ensured to achieve a good insulation effect.

[0038] According to research, the higher the weight of the insulating layer, the lower the thermal conductivity of the electromagnetic shielding cover, and the lower the weight of the insulating layer, the higher the thermal conductivity of the electromagnetic shielding cover. This is because the insulating material with a high gram weight has a tighter molecular structure, which limits the channel for heat transfer and reduces the thermal conductivity of the electromagnetic shielding cover. The high-gram weight of the insulating layer can ensure that the electromagnetic shielding cover has good insulation performance, reduce the risk of current leakage, and improve the safety of the equipment. By utilizing the relationship between the gram weight of the insulating layer and the thermal conductivity of the electromagnetic shielding cover, the gram weight of the insulating layer can be adjusted according to specific needs during the design, thereby obtaining an electromagnetic shielding cover with good heat dissipation performance and high shielding performance.

[0039] By limiting the relationship between the grammage of the insulating layer and the thermal conductivity of the electromagnetic shielding cover, the embodiment of the present invention can adjust the grammage of the insulating layer according to specific needs during design, thereby obtaining an electromagnetic shielding cover with good heat dissipation performance and high shielding performance, which is suitable for heat dissipation and electromagnetic shielding of components.

[0040] Exemplarily, the thermal conductivity of the insulating layer may be 15-55 W / (mK), for example, the thermal conductivity of the insulating layer may be 15 W / (mK), 20 W / (mK), 25 W / (mK), 30 W / (mK), 35 W / (mK), 40 W / (mK), 45 W / (mK), 50 W / (mK) or 55 W / (mK). The heat dissipation performance and the shielding performance may be met.

[0041] In some embodiments, the insulating layer optionally includes a filling layer and filler particles, the filler particles are dispersed in the filling layer, and the filling layer can be a resin material, such as acrylic resin or polyester resin. The filler particles are dispersed in the filling layer, and the filler particles can support the filling layer, thereby increasing the mechanical strength of the insulating layer 130 to a certain extent without affecting its flexibility, and the insulating layer 130 can protect the outer surface of the first shielding layer 120. The insulating layer 130 mainly has an insulating function to prevent the electromagnetic shielding cover from short-circuiting. The filler particles 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. The filler particles 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, and enhancing the electromagnetic shielding effect to a certain extent.

[0042] Filler particles can also affect thermal conductivity. By selecting suitable filling layer materials and filler particles, excellent thermal conductivity can be achieved while ensuring good insulation performance, thereby optimizing the overall performance of the electromagnetic shielding cover. For example, when heat is generated inside the electromagnetic shielding cover, the filler particles can conduct the heat to the outside through the filling layer, thereby improving the heat dissipation efficiency. This helps to reduce the temperature inside the electromagnetic shielding cover and prevent performance degradation or damage due to overheating. By adjusting the type, content and other parameters of the filling layer and filler particles, the thermal conductivity of different filling layers and the thermal conductivity of the filler particles can be obtained, thereby flexibly adjusting the thermal conductivity of the electromagnetic shielding cover. This enables the electromagnetic shielding cover to adapt to different working environments and application requirements, and improves the applicability and reliability of the product. Exemplarily, the thermal conductivity of the filler particles is at least 10W / (mK) greater than the thermal conductivity of the filling layer, and an insulating layer with better insulation performance and thermal conductivity can be obtained, thereby adjusting the thermal conductivity of the electromagnetic shielding cover.

[0043] In some embodiments, optionally, the thermal conductivity of the first shielding layer is at least 10W / (mK) greater than that of the insulating layer. That is, the thermal conductivity of the first shielding layer is greater than that of the insulating layer, and therefore, it is beneficial to improve the heat conduction speed, and the heat generated by the components on the circuit board can be quickly output to the insulating layer through the first shielding layer, and the insulating layer releases the heat to the side away from the circuit board, thereby preventing the performance degradation or damage of the components on the circuit board due to overheating.

[0044] In some embodiments, optionally, the thermal conductivity of the first connection layer is less than that of the first shielding layer, the heat transfer of the first shielding layer is fast, and the heat transfer of the first connection layer is slow, so that a large temperature difference can be formed on the two sides of the first connection layer, and the natural temperature difference is used to increase the speed of heat transfer from the first connection layer to the first shielding layer. At the same time, the first connection layer can also be used to slow down the heat dissipation in the electromagnetic shielding cover to a certain extent. Therefore, in some applications, some temperature-sensitive devices in the electromagnetic shielding cover can use a first connection layer with a lower thermal conductivity to slow down heat loss, avoid affecting these sensitive components, and ensure that they work within an appropriate temperature range. And a large temperature difference is formed by using the two sides of the first connection layer to ensure that after a certain period of time, the natural temperature difference can be used to stably dissipate heat. In addition, under normal circumstances, the cost of materials with better thermal conductivity is higher. By using a first connection layer with a lower thermal conductivity, the manufacturing cost of the electromagnetic shielding cover can be reduced while meeting performance requirements.

[0045] In some embodiments, the insulating layer may include a base layer and an adhesive layer, wherein the base layer is disposed on one side of the adhesive layer, and the adhesive layer faces 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. The adhesive layer may be made of the same material as the filling layer, so the adhesive layer and the filling layer may be arranged in the same layer as the resin material, and the resin material electromagnetic shielding cover may enhance the overall bonding force between the insulating layer and the first shielding layer when pressed together.

[0046] Figure 2 A schematic diagram of the structure of another electromagnetic shielding cover is provided for an embodiment of the present invention, see Figure 2 The electromagnetic shielding cover of this embodiment is compared with Figure 1 The difference is that the first shielding layer 120 is provided with a plurality of first hollow portions 121 , and the first connecting layer 110 is connected to the insulating layer 130 via the first hollow portions 121 .

[0047] 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.

[0048] As an optional embodiment, in the above embodiment, 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, and 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.

[0049] As an optional embodiment, Figure 3 A schematic diagram of the structure of another electromagnetic shielding cover is provided for an embodiment of the present invention, see Figure 3 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.

[0050] 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 electromagnetic shielding cover of this embodiment is compared with Figure 1The difference is that the electromagnetic shielding cover further comprises a first conductive layer 140, and the first conductive layer 140 is arranged on a side of the first shielding layer 120 close to and / or away from the insulating layer. In the figure, the first conductive layer 140 is arranged on a side of the first shielding layer 120 away from the insulating layer as an example for description.

[0051] 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.

[0052] 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 electromagnetic shielding cover also includes a second connection layer 150, and the second connection layer 150 is arranged between the first shielding layer 120 and the first conductive layer 140. Specifically, the second connection layer 150 is separately 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, thereby improving 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.

[0053] As an optional embodiment, Figure 6 A schematic diagram of the structure of another electromagnetic shielding cover is provided for an embodiment of the present invention, see Figure 6The 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.

[0054] As an optional embodiment, continue to refer to Figure 6 The 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.

[0055] 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 effectiveness 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.

[0056] 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 of this embodiment is compared with Figure 1The difference is that the electromagnetic shielding cover also includes a second shielding layer 160 and a second connecting layer 150, the second shielding layer 160 is arranged between the first shielding layer 120 and the first connecting layer 110, and the second connecting layer 150 is arranged between the first shielding layer 120 and the second shielding layer 160. Specifically, the second connecting layer 150 is used to improve the bonding force between the first shielding layer 120 and the second shielding layer 160, and the second connecting layer 150 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.

[0057] As an optional embodiment, see Figure 7 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 second shielding layer 160 and the first shielding layer 120 may be guided out by the conductive particles 111.

[0058] 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 second connection layer 150 may be provided with conductive particles 111. Specifically, the second connection layer 150 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 first conductive layer 140 may be connected to the second connection layer 150 through the conductive particles 111, and the first shielding layer 120 may guide the electromagnetic interference signal through the second connection layer 150, the second shielding layer 160 and the first connection layer 110 to improve the shielding effect.

[0059] As an optional embodiment, 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 first shielding layer 120 is provided with a plurality of first hollow portions 121 , and the second connecting layer 150 is connected to the insulating layer 130 through the first hollow portions 121 .

[0060] 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 150 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 second connection layer 150 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.

[0061] 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 second connection layer 150 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 second connection layer 150 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 second connection layer 150 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.

[0062] 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.

[0063] 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.

[0064] As an optional embodiment, the second connection layer 150 is provided with conductive particles 111, and the first shielding layer 120 and the second shielding layer 160 are electrically connected through the conductive particles 111. In other words, the first shielding layer 120 and the second shielding layer 160 are conductive, and the first shielding layer 120 can export the electromagnetic interference signal through the second connection layer 150, the second shielding layer 160 and the first connection layer 110, thereby improving the shielding effect.

[0065] 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.

[0066] As an optional embodiment, continue to refer to Fig. 9 The first shielding layer 120 includes a first supporting layer 122 and a first metal layer (not shown in the figure), the first supporting layer 122 is provided with a plurality of first hollow portions 121, the first hollow portions 121 are arranged 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 portions 121, and the second connecting layer 150 is connected to the insulating layer 130 through the first hollow portions 121

[0067] Specifically, the first support layer 122 serves as the main structure of the first shielding layer 120 and is used to provide the overall framework of the first shielding layer 120. In order to meet the flexibility requirements, the first support layer 122 can be a non-woven fabric, an insulating textile fabric, a composite material, a cotton and linen 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, chemical plating, spraying, etc., thereby forming a shielding layer with a shielding effect. Furthermore, the adjacent connecting layer can pass through the first shielding layer 120 and connect to 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 top-view shape of the first hollow portion 121 is an irregular shape. In other embodiments, the top-view shape of the first hollow portion 121 can also be a quadrilateral, a polygon or a circle, which is conducive to releasing the stress of the first shielding layer 120 during stretching and bending, and further improving the bending performance of the first shielding layer 120.

[0068] As an optional embodiment, continue to refer to Fig. 9 Similarly, the second shielding layer 160 includes a second supporting layer 162 and a second metal layer (not shown in the figure), the second supporting layer 162 is provided with a plurality of second hollow portions 161, the second hollow portions 161 are 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 portions 161, and the second connecting layer 150 is connected to the first connecting layer 110 through the second hollow portions 161.

[0069] Specifically, the second supporting layer 162 serves as the main structure of the second shielding layer 160 and is used to provide an overall frame of the second shielding layer 160. In order to meet the flexibility requirement, the second supporting layer 162 may be a non-woven fabric, an insulating textile fabric, a composite material, a cotton and linen 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, chemical plating, spraying, etc., thereby forming a shielding layer with a shielding effect. The adjacent first connecting layer 110 can pass through the second shielding layer 160 through the second hollow portion 161 to connect with another film layer, so the bonding force provided by the first connecting layer 110 can be used to increase the bonding force. Among them, the top-view shape of the second hollow portion 161 is an irregular shape. In other embodiments, the top-view 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, which is beneficial to releasing the stress of stretching and bending of the second shielding layer 160, and further improving the bending performance of the second shielding layer 160.

[0070] 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.

[0071] In application, the electromagnetic shielding cover is covered on the circuit board and adhered to the surface of electronic components. The electromagnetic shielding cover provided by the present invention satisfies the functional relationship between the gram weight of the insulating layer and the thermal conductivity of the electromagnetic shielding cover, and can obtain an electromagnetic shielding cover with good heat dissipation performance and high shielding performance, which is suitable for heat dissipation and electromagnetic shielding of components.

[0072] The present invention also provides an application of an electromagnetic shielding cover, Figure 1-Figure 9 .

[0073] Example 1

[0074] The present embodiment provides an electromagnetic shielding cover comprising: a stacked connection layer 110, a first shielding layer 120 and an insulating layer 130, wherein the first shielding layer 120 is a non-woven fabric with a sputtered metal layer, wherein the gram weight of the insulating layer is 0.672 g / dm 2 The thermal conductivity of the electromagnetic shielding cover is 19W / (mK). The weight of the insulating layer and the thermal conductivity of the electromagnetic shielding cover satisfy: K ​​= A*f+B; where f is the weight of the insulating layer, in g / dm 2 ; K is the thermal conductivity of the electromagnetic shielding cover, the unit is W / (mK); A=-183, B=142.

[0075] Example 2

[0076] The present embodiment provides an electromagnetic shielding cover comprising: a stacked connection layer 110, a second shielding layer, a connection layer, a first shielding layer 120 and an insulating layer 130, wherein the first shielding layer 120 is a non-woven fabric with a sputtered metal layer, wherein the gram weight of the insulating layer is 0.597 g / dm 2 The thermal conductivity of the electromagnetic shielding cover is 37W / (mK), and the gram weight of the insulating layer and the thermal conductivity of the electromagnetic shielding cover satisfy: K=A*f+B; where f is the gram weight of the insulating layer, the unit is g / dm2; K is the thermal conductivity of the electromagnetic shielding cover, the unit is W / (mK); A=-191, B=151.

[0077] Example 3

[0078] The present embodiment provides an electromagnetic shielding cover comprising: a stacked connection layer 110, a second shielding layer, a connection layer, a first shielding layer 120 and an insulating layer 130, wherein the first shielding layer 120 is a non-woven fabric with a sputtered metal layer, wherein the gram weight of the insulating layer is 0.619 g / dm 2 The thermal conductivity of the electromagnetic shielding cover is 52W / (mK). The weight of the insulating layer and the thermal conductivity of the electromagnetic shielding cover satisfy: K ​​= A*f+B; where f is the weight of the insulating layer, in g / dm 2 ; K is the thermal conductivity of the electromagnetic shielding cover, the unit is W / (mK); A=-197, B=174.

[0079] Comparative Example 1

[0080] The present embodiment provides an electromagnetic shielding cover comprising: a stacked connection layer 110, a first shielding layer 120 and an insulating layer 130, wherein the first shielding layer 120 is a non-woven fabric with a sputtered metal layer, wherein the gram weight of the insulating layer is 0.9 g / dm 2 , the thermal conductivity of the electromagnetic shielding cover is 72W / (mK), which does not satisfy: K=A*f+B.

[0081] Comparative Example 2

[0082] This embodiment provides an electromagnetic shielding cover comprising: a stacked connection layer 110, a first shielding layer 120 and an insulating layer 130, wherein the first shielding layer 120 is a non-woven fabric with a sputtered metal layer, and the gram weight of the insulating layer is 1.190 g / dm 2 , the thermal conductivity of the electromagnetic shielding cover is 10W / (mK), which does not satisfy: K=A*f+B.

[0083] In the above embodiment, the thermal conductivity is measured using a TDTR measurement system, and the thermal conductivity is measured using the time-domain thermoreflectance method (TDTR). The test parameters are laser wavelength: 780nm or 800nm ​​(common laser wavelengths). Time resolution: picoseconds (ps). Using the electromagnetic shielding cover of the above embodiment and the comparative example, the electromagnetic shielding cover of the above embodiment and the comparative example is covered on an FPC circuit board provided with a PTC heater, and the current passing through is adjusted by controlling the voltage, thereby adjusting the power and heat generation. After the PTC heater is raised to 60°C at room temperature, the temperature is maintained and the timing is started, and the temperature of the outer layer of the electromagnetic shielding cover is calculated to rise to 60°C. In addition, a network analyzer is used to test the shielding effectiveness of each embodiment and the comparative example at 5GHz.

[0084] Table 1 Test parameters of various embodiments and comparative examples

[0085]

[0086] It can be seen that the gram weight of the insulating layer of the electromagnetic shielding cover in embodiments 1-3 of the present invention and the thermal conductivity of the electromagnetic shielding cover satisfy: K=A*f+B; an electromagnetic shielding cover with good heat dissipation performance and high shielding performance can be obtained, which is suitable for heat dissipation and electromagnetic shielding of components.

[0087] 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: Insulating layer; wherein the gram weight of the insulating layer and the thermal conductivity of the electromagnetic shielding cover satisfy: K = A*f + B; Wherein, f is the weight of the insulating layer, in g / dm 2 ; K is the thermal conductivity of the electromagnetic shielding cover, in units of W / (mK); -180≤A≤-200; 140≤B≤180, and the calculation is dimensionless.

2. The electromagnetic shielding cover according to claim 1, characterized in that: The thermal conductivity of the insulating layer is 15-55 W / (mK).

3. The electromagnetic shielding cover according to claim 1, characterized in that: The insulating layer includes a filling layer and filler particles, the filler particles are dispersed in the filling layer, and a thermal conductivity of the filler particles is at least 10 W / (mK) greater than a thermal conductivity of the filling layer.

4. The electromagnetic shielding cover according to claim 1, characterized in that: The electromagnetic shielding cover further includes a first shielding layer, which is disposed on a side of the insulating layer. The thermal conductivity of the first shielding layer is at least 10 W / (mK) greater than that of the insulating layer.

5. The electromagnetic shielding cover according to claim 4, characterized in that: The electromagnetic shielding cover further includes a first connection layer, which is disposed on a side of the first shielding layer away from the insulating layer, and the thermal conductivity of the first connection layer is smaller than the thermal conductivity of the first shielding layer.

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 on a side of the first shielding layer close to and / or away from the insulating layer.

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

8. The electromagnetic shielding cover according to claim 7, characterized in that: The first shielding layer includes a first supporting layer and a first metal layer, the first supporting layer is provided with a first hollow portion, and the first metal layer covers the surface of the first supporting layer and the inner wall of the first hollow portion; and / or, The second shielding layer includes a second supporting layer and a second metal layer. The second supporting layer is provided with a second hollow portion. The second metal layer covers the surface of the second supporting layer and the inner wall of the second hollow portion.

9. The electromagnetic shielding cover according to any one of claims 7 to 8, characterized in that: Conductive particles are disposed in the first connecting layer and / or the second connecting layer.

10. The electromagnetic shielding cover according to any one of claims 7 to 8, characterized in that: The thickness of the first shielding layer and the second shielding layer ranges from 10 to 50 μm.

11. The electromagnetic shielding cover according to any one of claims 7 to 8, characterized in that: The first shielding layer and / or the second shielding layer is / are conductive non-woven fabric.

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

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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