Heat-conducting electromagnetic shielding material with vertical orientation structure as well as preparation method and application of heat-conducting electromagnetic shielding material

Abstract

The invention provides a heat-conducting electromagnetic shielding material with a vertical orientation structure as well as a preparation method and application of the heat-conducting electromagnetic shielding material. The heat-conducting electromagnetic shielding material with the vertical orientation structure comprises a heat-conducting composite material layer and an electromagnetic shielding film layer, the heat-conducting composite material layers and the electromagnetic shielding film layers are alternately arranged to form a layered structure, and the orientation direction is the same as the thickness direction; the preparation raw materials of the heat-conducting composite material layer comprise organic silicon resin and filler; the filler comprises a heat-conducting filler. The heat-conducting electromagnetic shielding material with the vertical orientation structure provided by the invention has excellent out-of-plane heat conduction and electromagnetic shielding functions at the same time.

Description

Technical Field

[0001] The invention belongs to the technical field of composite materials, and in particular relates to a vertically oriented structured thermal conductive electromagnetic shielding material and a preparation method and application thereof. Background Art

[0002] The high-density stacking of electronic components enables high-power computing and communication in miniaturized devices, but the high-density stacking causes a large amount of electromagnetic wave pollution and heat accumulation when the electronic components are working, which greatly reduces the performance and service life of the electronic components. This has led to an increasing demand for heat dissipation and electromagnetic interference shielding. However, the thermal conductivity and electromagnetic shielding properties of existing electronic materials are often difficult to balance and cannot meet the requirements.

[0003] CN116669412A discloses a heterogeneous structure heat-conducting electromagnetic shielding silicone rubber and its preparation method. The heterogeneous structure heat-conducting electromagnetic shielding silicone rubber is a structure in which an outer layer wraps an inner layer. The inner layer is a heat-conducting and conductive electromagnetic shielding silicone layer, and the outer layer is a heat-conducting and insulating electromagnetic shielding silicone layer. The heat-conducting and conductive electromagnetic shielding silicone layer includes 10% to 90% heat-conducting and conductive electromagnetic shielding fillers and 10 to 90% silicone rubber by weight, and the heat-conducting and insulating electromagnetic shielding silicone layer includes 10% to 90% heat-conducting and insulating electromagnetic shielding fillers and 10 to 90% silicone rubber by weight. The heterogeneous structure heat-conducting and electromagnetic shielding silicone rubber prepared by this technical solution has a high electromagnetic shielding effectiveness, but a low thermal conductivity, less than 2.3W / m -1 K -1 .

[0004] CN111019350A discloses a silicone composite material with high thermal conductivity and excellent electromagnetic shielding performance. The composition of the silicone composite material with high thermal conductivity and excellent electromagnetic shielding performance is as follows: 1-3g of MXene material; 3-5g of h-BN material; 0.5-1.5g of single-layer graphene powder; 20-50g of urea; 10-45g of silicone. The silicone composite material with high thermal conductivity and excellent electromagnetic shielding performance obtained by this technical solution has a high in-plane thermal conductivity, but relatively low electromagnetic shielding performance and out-of-plane thermal conductivity, and poor heat dissipation effect when used as an electronic packaging material.

[0005] Therefore, it is necessary to develop a new type of lightweight material with integrated thermal conductivity and electromagnetic shielding functions and high out-of-plane thermal conductivity. Summary of the invention

[0006] In view of the deficiencies in the prior art, an object of the present invention is to provide a vertically oriented structured thermally conductive electromagnetic shielding material and a preparation method and application thereof, wherein the vertically oriented structured thermally conductive electromagnetic shielding material has both excellent out-of-plane thermal conductivity and electromagnetic shielding functions.

[0007] To achieve the object of the present invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a vertically oriented structure thermally conductive electromagnetic shielding material, and the vertically oriented structure thermally conductive electromagnetic shielding material includes a thermally conductive composite layer and an electromagnetic shielding film layer; the thermally conductive composite layer and the electromagnetic shielding film layer are alternately arranged to form a layered structure, and the orientation direction is the same as the thickness direction;

[0009] The preparation raw materials of the thermally conductive composite layer include silicone resin and fillers; the fillers include thermally conductive fillers.

[0010] In the present invention, the vertically oriented structure means that the orientation direction is the same as the thickness direction, perpendicular or approximately perpendicular to the extension direction, as Figure 1 shown, Z is the thickness direction.

[0011] In the present invention, in the vertically oriented structure thermally conductive electromagnetic shielding material, the thermally conductive composite layer and the electromagnetic shielding film layer are alternately arranged to form a layered structure, and the orientation direction is the same as the thickness direction, so that the vertically oriented structure thermally conductive electromagnetic shielding material has excellent out-of-plane thermal conductivity and electromagnetic shielding functions at the same time.

[0012] Preferably, the outermost layers on both sides of the vertically oriented structure thermally conductive electromagnetic shielding material that are alternately arranged are thermally conductive composite layers.

[0013] Preferably, the silicone resin includes a thermosetting silicone resin.

[0014] Preferably, the thermosetting silicone resin includes any one or a combination of at least two of polyalkyl silicone resin, polyaryl silicone resin or polyalkylaryl silicone resin.

[0015] Preferably, the mass ratio of the filler to the silicone resin is (3-5):1, such as 3.2:1, 3.4:1, 3.6:1, 3.8:1, 4.0:1, 4.2:1, 4.4:1, 4.6:1 or 4.8:1, etc.

[0016] Preferably, the thermally conductive filler includes one-dimensional thermally conductive filler and / or two-dimensional thermally conductive filler.

[0017] In the present invention, the thermally conductive filler is preferably one-dimensional thermally conductive filler and / or two-dimensional thermally conductive filler. By using the anisotropic structure of the thermally conductive filler, a thermally conductive path with a certain orientation can be constructed, reducing the chaotic transmission path of heat flow in the vertically oriented structure thermally conductive electromagnetic shielding material, and due to the soft characteristics of the thermosetting silicone resin, it helps to reduce the interfacial thermal resistance between the vertically oriented structure thermally conductive electromagnetic shielding material and other external materials, so that the vertically oriented structure thermally conductive electromagnetic shielding material obtains excellent thermal conductivity.

[0018] Preferably, the thermal conductive filler has electrical conductivity.

[0019] In the present invention, the thermal conductive filler is preferably a thermal conductive filler with electrical conductivity, which is beneficial to improving the near-field shielding effectiveness of the vertically oriented structure thermal conductive electromagnetic shielding material.

[0020] Preferably, the thermal conductive filler includes any one or a combination of at least two of carbon fiber, graphite sheet, graphene, carbon nanotube or surface metallized filler.

[0021] Preferably, the surface metallized filler includes any one or a combination of at least two of surface metal-plated graphite, surface metal-plated carbon fiber or surface metal-plated carbon nanotube.

[0022] Preferably, the metal in the surface metallized filler includes any one or a combination of at least two of gold, silver, copper, nickel or tin.

[0023] Preferably, the surface metal-plated graphite includes nickel-coated graphite.

[0024] Preferably, the average length of the carbon fiber is 50 - 3000 μm, such as 100 μm, 300 μm, 500 μm, 700 μm, 900 μm, 1100 μm, 1300 μm, 1500 μm, 1700 μm, 1900 μm, 2100 μm, 2300 μm, 2500 μm, 2700 μm or 2900 μm, etc., and further preferably 100 - 500 μm.

[0025] Preferably, the filler further includes a thermal conductivity enhancing filler.

[0026] Preferably, the thermal conductivity enhancing filler includes any one or a combination of at least two of alumina, silicon carbide, silicon oxide, aluminum nitride, magnesium oxide or zinc oxide.

[0027] Preferably, the shape of the thermal conductivity enhancing filler includes any one or a combination of at least two of spherical, quasi-spherical, flaky or fibrous.

[0028] Preferably, the mass ratio of the thermal conductive filler to the thermal conductivity enhancing filler is (0.5 - 8):1, such as 1:1, 2:1, 3:1, 4:1, 5:1, 6:1 or 7:1, etc., and further preferably (1 - 4):1, and more preferably 1:1.

[0029] In the present invention, the synergistic effect between the thermal conductive filler and the thermal conductivity enhancing filler significantly improves the thermal conductivity and electromagnetic shielding effectiveness of the vertically oriented structure thermal conductive electromagnetic shielding material.

[0030] Preferably, the filler further includes an electrically conductive filler and / or a magnetic filler.

[0031] In the present invention, the filler preferably further includes a conductive filler and / or a magnetic filler. Adding the conductive filler and / or the magnetic filler can further improve the electromagnetic shielding effectiveness, so that the vertically oriented structure thermally conductive electromagnetic shielding material realizes the unity of high thermal conductivity and high-efficiency electromagnetic shielding functions.

[0032] Preferably, the conductive filler includes any one or a combination of at least two of carbon black, gold powder, silver powder, copper powder, nickel powder, aluminum powder, silver-coated copper powder, silver-coated aluminum powder, silver-coated nickel powder, metal-coated glass fibers or metal-coated glass microspheres.

[0033] Preferably, the metals in the metal-coated glass fibers and the metal-coated glass microspheres each independently include any one or a combination of at least two of gold, silver, copper, nickel or tin.

[0034] Preferably, the metal-coated glass fibers include silver-coated glass fibers.

[0035] Preferably, the metal-coated glass microspheres include silver-coated glass microspheres.

[0036] Preferably, the magnetic filler includes any one or a combination of at least two of nickel powder, ferrite powder, cobalt powder, iron nitride powder or carbonyl iron powder.

[0037] Preferably, the ferrite powder includes magnetite nanoparticles.

[0038] Preferably, the shapes of the conductive filler and the magnetic filler each independently include any one or a combination of at least two of spherical, quasi-spherical, flaky or fibrous.

[0039] Preferably, the ratio of the mass of the thermal conductive filler, the mass of the thermal conductivity enhancing filler to the total mass of the conductive filler and / or the magnetic filler is (1-8):(0.5-4):1, such as 2:1:1, 2:2:1, 2:3:1, 4:1:1, 4:2:1, 4:3:1, 6:1:1, 6:2:1, 6:3:1, 8:1:1, 8:2:1 or 8:3:1, etc., more preferably (2-3):(1-1.5):1, and still more preferably 2:1:1.

[0040] Preferably, the electromagnetic shielding film layer includes an electromagnetic shielding material having a network or porous structure.

[0041] Preferably, the electromagnetic shielding material having a network or porous structure includes a metal mesh, a woven metal fiber cloth or a fiber cloth with a metal coating on the surface.

[0042] Preferably, the metals in the metal mesh, the woven metal fiber cloth or the fiber cloth with a metal coating on the surface each independently include a pure metal or an alloy.

[0043] Preferably, the number of layers of the thermally conductive composite material layer in the vertically oriented structure thermally conductive electromagnetic shielding material ≥ 5 (such as 11, 21, 31, 41, 51, 61, 71, 81, or 91, etc.), and the number of layers of the electromagnetic shielding film layer ≥ 4 (such as 10, 20, 30, 40, 50, 60, 70, 80, or 90, etc.).

[0044] In the present invention, the vertically oriented structure thermally conductive electromagnetic shielding material can obtain both high thermal conductivity and electromagnetic shielding performance. By adjusting the type and proportion of the filler, and the thickness and number of layers of the laminate, the regulation of the thermal conductivity and electromagnetic shielding performance can be achieved.

[0045] In a second aspect, the present invention provides a preparation method of the vertically oriented structure thermally conductive electromagnetic shielding material as described in the first aspect. The preparation method includes the following steps:

[0046] (1) Mix the silicone resin and the filler, and obtain the thermally conductive composite material by using an orientation forming process.

[0047] (2) Alternately laminate and press and cure the thermally conductive composite material prepared in step (1) and the electromagnetic shielding film to obtain the vertically oriented structure thermally conductive electromagnetic shielding material.

[0048] Preferably, the orientation forming process in step (1) includes extrusion molding or roll pressing molding.

[0049] Preferably, the pressing in step (2) includes roll pressing or hot pressing.

[0050] In the present invention, by means of roll pressing or hot pressing, the silicone resin and its filler in the thermally conductive composite material can penetrate into the electromagnetic shielding film with a network or porous structure, so that good bonding is formed between layers.

[0051] Preferably, the curing in step (2) includes thermal curing.

[0052] Preferably, after the curing in step (2), it further includes the step of cutting along the direction perpendicular to the orientation.

[0053] Preferably, the thickness of the thermally conductive composite material in step (1) is 0.1 - 2 mm, such as 0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm, 1.0 mm, 1.2 mm, 1.4 mm, 1.6 mm, or 1.8 mm, etc.

[0054] Preferably, the thickness of the electromagnetic shielding film in step (2) is 0.01 - 0.2 mm, such as 0.03 mm, 0.05 mm, 0.07 mm, 0.09 mm, 0.11 mm, 0.13 mm, 0.15 mm, 0.17 mm, or 0.19 mm, etc.

[0055] Preferably, the thickness of the vertically oriented structure thermally conductive electromagnetic shielding material is 0.1 - 50 mm, such as 1 mm, 3 mm, 5 mm, 10 mm, 20 mm, 30 mm or 40 mm, etc., more preferably 0.1 - 5 mm, and even more preferably 0.5 - 3 mm.

[0056] In the present invention, the thickness of the vertically oriented structure thermally conductive electromagnetic shielding material is preferably 0.5 - 3 mm, which can meet the packaging and usage requirements of general electronic devices in terms of thickness.

[0057] In a third aspect, the present invention provides an application of the vertically oriented structure thermally conductive electromagnetic shielding material as described in the first aspect in electronic packaging.

[0058] In the present invention, the vertically oriented structure thermally conductive electromagnetic shielding material has excellent out-of-plane thermal conductivity and electromagnetic shielding functions in the application of electronic packaging. As Figure 2 shown, the package includes a heat sink 1, a vertically oriented structure thermally conductive electromagnetic shielding material 2, a chip 3, a package substrate 4, and a printed circuit board 5. The high out-of-plane thermal conductivity of the vertically oriented structure thermally conductive electromagnetic shielding material 2 can quickly transfer heat to the heat sink to achieve heat dissipation; when electromagnetic waves propagate to the vertically oriented structure thermally conductive electromagnetic shielding material, the vertically arranged thermally conductive composite material layer can reflect a part of the electromagnetic waves. After the remaining electromagnetic waves reach the laminated electromagnetic shielding film layer, they will be further reflected, thereby effectively preventing electromagnetic wave leakage, improving the near-field shielding efficiency, and reducing electromagnetic wave pollution.

[0059] Compared with the prior art, the present invention has the following beneficial effects:

[0060] In the vertically oriented structure thermally conductive electromagnetic shielding material of the present invention, the thermally conductive composite material layer and the electromagnetic shielding film layer are alternately arranged to form a layered structure, and the orientation direction is the same as the thickness direction, so that the vertically oriented structure thermally conductive electromagnetic shielding material has excellent out-of-plane thermal conductivity and electromagnetic shielding functions at the same time. The out-of-plane thermal conductivity of the vertically oriented structure thermally conductive electromagnetic shielding material is ≥5 W / m -1 K -1 , and the near-field shielding efficiency is ≥44 dB. In a preferred case, the out-of-plane thermal conductivity is ≥8 W / (m·K), and the near-field shielding efficiency ≥50 dB. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 Schematic diagram of the preparation process of the vertically oriented structure thermally conductive electromagnetic shielding material provided for Example 1;

[0062] Figure 2 Schematic diagram of the application of the vertically oriented structure thermally conductive electromagnetic shielding material in electronic packaging;

[0063] Among them, 1 - heat sink; 2 - vertically oriented structure thermally conductive electromagnetic shielding material; 3 - chip; 4 - packaging substrate; 5 - printed circuit board;

[0064] Figure 3 Schematic diagram of the structure of the vertically oriented structure thermally conductive electromagnetic shielding material provided in Example 1;

[0065] Among them, 1 - thermally conductive composite layer; 2 - electromagnetic shielding film layer; 3 - thickness; 4 - alternately arranged structure of omitted thermally conductive composite layers and electromagnetic shielding film layers;

[0066] Figure 4 Schematic diagram of the contact between the metal frame and the vertically oriented structure thermally conductive electromagnetic shielding material during the near - field shielding test of the vertically oriented structure thermally conductive electromagnetic shielding material provided in Example 1;

[0067] Among them, 1 - vertically oriented structure thermally conductive electromagnetic shielding material; 2 - metal frame; 3 - contact position between the metal frame and the vertically oriented structure thermally conductive electromagnetic shielding material. Detailed implementation manners

[0068] The technical solutions of the present invention will be further described below through specific implementation manners. Those skilled in the art should understand that the described embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0069] Example 1

[0070] This example provides a vertically oriented structure thermally conductive electromagnetic shielding material and its preparation method. As Figure 3 shown, the vertically oriented structure thermally conductive electromagnetic shielding material includes a thermally conductive composite layer 1 and an electromagnetic shielding film layer 2; the thermally conductive composite layer and the electromagnetic shielding film layer are alternately arranged to form a layered structure, and the orientation direction is the same as the thickness 3 direction;

[0071] The raw materials for preparing the thermally conductive composite layer are a filler and a silicone resin (two - component methyl vinyl siloxane, manufacturer: Dow Chemical Company, grade: SYLGARD TM 527) with a mass ratio of 4:1; the filler is a thermally conductive filler (carbon fiber, average length of 250 μm, diameter of 10 μm), a thermally conductive enhancing filler (spherical alumina, D50 particle size of 3 μm), and a conductive filler (flake silver powder, D50 particle size of 5 μm) with a mass ratio of 2:1:1.

[0072] The preparation method of the vertically oriented structure thermally conductive electromagnetic shielding material is as follows:

[0073] (1) Mix component A and component B of the two-component methyl vinyl siloxane in a mass ratio of 1:1, disperse them evenly through a vacuum mixer to form a silicone resin, then blend and stir evenly with the filler, and obtain a thermal conductive composite material with a thickness of 1 mm through extrusion molding. Cut the thermal conductive composite material into sheets with dimensions of 40×80 mm 2 to obtain a thermal conductive composite material with dimensions of 40×80×1 mm 3 ;

[0074] (2) As shown in Figure 1 , alternately stack the 40×80×1 mm 3 thermal conductive composite material prepared in step (1) and a 40×80×0.05 mm 3 electromagnetic shielding film (tinned fiber cloth, manufacturer: Shenzhen Zhuohan Material Technology Co., Ltd., thickness 0.05 mm) in a rectangular mold. A total of 31 sheets of the thermal conductive composite material are stacked, and a total of 30 sheets of the tinned fiber cloth are stacked. Then, use a hot pressing process to press the stacked thermal conductive composite material and the tinned fiber cloth together. The pressure of the hot pressing is 2 MPa, the temperature is 120 °C, and the time is 20 min. Then transfer it to an oven at 130 °C for curing for 2 h. After curing is completed, cut it along the direction perpendicular to the orientation (i.e., perpendicular to the Figure 1 Z direction in

[0075] Example 2

[0076] This example provides a vertically oriented structure thermal conductive electromagnetic shielding material and its preparation method. The difference from Example 1 is only that the raw materials for preparing the thermal conductive composite material layer are a filler and a silicone resin (two-component methyl vinyl siloxane, manufacturer: Dow Chemical Company, grade: SYLGARD TM 527) in a mass ratio of 5:1; the filler is a thermal conductive filler (carbon fiber, average length 150 μm, diameter 10 μm), a thermal conductive enhancing filler (spherical alumina, D50 particle size 3 μm), and an electrically conductive filler (flake silver powder, D50 particle size 5 μm) in a mass ratio of 2.5:1.5:1.

[0077] In the preparation method of the vertically oriented structure thermal conductive electromagnetic shielding material, after curing in step (2), cut it along the direction perpendicular to the orientation to obtain a vertically oriented structure thermal conductive electromagnetic shielding material with a thickness of 3 mm.

[0078] Other conditions are the same as those in Example 1.

[0079] Example 3

[0080] This embodiment provides a vertically oriented structure thermally conductive electromagnetic shielding material and its preparation method. The difference from Embodiment 1 is only that the raw materials for preparing the thermally conductive composite material layer are filler and silicone resin (two-component methyl vinyl siloxane, manufacturer: Dow Chemical Company, grade: SYLGARD TM 527) with a mass ratio of 3.5:1; the filler is a thermally conductive filler (carbon fiber, average length of 500 μm, diameter of 10 μm), a thermally conductive enhancing filler (spherical alumina, D50 particle size of 3 μm), and a conductive filler (flake silver powder, D50 particle size of 5 μm) with a mass ratio of 3:1.25:1.

[0081] In the preparation method of the vertically oriented structure thermally conductive electromagnetic shielding material, after the curing in step (2) is completed, it is cut along the direction perpendicular to the orientation to obtain a vertically oriented structure thermally conductive electromagnetic shielding material with a thickness of 0.3 mm.

[0082] Other conditions are the same as those in Embodiment 1.

[0083] Embodiment 4

[0084] This embodiment provides a vertically oriented structure thermally conductive electromagnetic shielding material and its preparation method. The difference from Embodiment 1 is only that the mass ratio of the thermally conductive filler (carbon fiber, average length of 250 μm, diameter of 10 μm), the thermally conductive enhancing filler (spherical alumina, D50 particle size of 3 μm), and the conductive filler (flake silver powder, D50 particle size of 5 μm) is adjusted to 1:4:1; other conditions are the same as those in Embodiment 1.

[0085] Embodiment 5

[0086] This embodiment provides a vertically oriented structure thermally conductive electromagnetic shielding material and its preparation method. The difference from Embodiment 1 is only that the mass ratio of the thermally conductive filler (carbon fiber, average length of 250 μm, diameter of 10 μm), the thermally conductive enhancing filler (spherical alumina, D50 particle size of 3 μm), and the conductive filler (flake silver powder, D50 particle size of 5 μm) is adjusted to 8:0.5:1; other conditions are the same as those in Embodiment 1.

[0087] Embodiment 6

[0088] This embodiment provides a vertically oriented structure thermally conductive electromagnetic shielding material and its preparation method. The difference from Embodiment 1 is only that the thermally conductive filler (carbon fiber, average length of 250 μm, diameter of 10 μm) is replaced with the same mass of thermally conductive filler (carbon fiber, average length of 50 μm, diameter of 10 μm); other conditions are the same as those in Embodiment 1.

[0089] Embodiment 7

[0090] This embodiment provides a vertically oriented structure thermally conductive electromagnetic shielding material and its preparation method. The difference from Embodiment 1 is only that the thermally conductive filler (carbon fiber, average length 250 μm, diameter 10 μm) is replaced with the same mass of thermally conductive filler (carbon fiber, average length 3000 μm, diameter 10 μm); other conditions are the same as those in Embodiment 1.

[0091] Embodiment 8

[0092] This embodiment provides a vertically oriented structure thermally conductive electromagnetic shielding material and its preparation method. The difference from Embodiment 1 is only that the thermally conductive filler (carbon fiber, average length 250 μm, diameter 10 μm) is replaced with the same mass of thermally conductive filler (flake graphene, D50 particle size 5 μm); other conditions are the same as those in Embodiment 1.

[0093] Embodiment 9

[0094] This embodiment provides a vertically oriented structure thermally conductive electromagnetic shielding material and its preparation method. The difference from Embodiment 1 is only that the thermally conductive reinforcing filler (spherical alumina, D50 particle size 3 μm) is replaced with the same mass of thermally conductive reinforcing filler (spherical silicon carbide, D50 particle size 1 μm); other conditions are the same as those in Embodiment 1.

[0095] Embodiment 10

[0096] This embodiment provides a vertically oriented structure thermally conductive electromagnetic shielding material and its preparation method. The difference from Embodiment 1 is only that the conductive filler (flake silver powder, D50 particle size 5 μm) is replaced with the same mass of conductive filler (flake copper powder, D50 particle size 3 μm); other conditions are the same as those in Embodiment 1.

[0097] Embodiment 11

[0098] This embodiment provides a vertically oriented structure thermally conductive electromagnetic shielding material and its preparation method. The difference from Embodiment 1 is only that the conductive filler (flake silver powder, D50 particle size 5 μm) is replaced with the same mass of magnetic filler (magnetite nanoparticles, spherical shape, D50 particle size 5 μm); other conditions are the same as those in Embodiment 1.

[0099] Embodiment 12

[0100] This embodiment provides a vertically oriented structure thermally conductive electromagnetic shielding material and its preparation method. The difference from Embodiment 1 is only that the filler is adjusted to a thermally conductive filler (carbon fiber, average length 250 μm, diameter 10 μm) and a thermally conductive reinforcing filler (spherical alumina, D50 particle size 3 μm) with a mass ratio of 1:1; other conditions are the same as those in Embodiment 1.

[0101] Embodiment 13

[0102] This embodiment provides a vertically oriented structure thermally conductive electromagnetic shielding material and a preparation method thereof. The difference from Embodiment 1 is only that the fillers are adjusted to a thermally conductive filler (carbon fiber, average length of 250 μm, diameter of 10 μm) and a thermal conductivity enhancing filler (spherical alumina, D50 particle size of 3 μm) with a mass ratio of 4:1; other conditions are the same as those in Embodiment 1.

[0103] Embodiment 14

[0104] This embodiment provides a vertically oriented structure thermally conductive electromagnetic shielding material and a preparation method thereof. The difference from Embodiment 1 is only that the fillers are adjusted to a thermally conductive filler (carbon fiber, average length of 250 μm, diameter of 10 μm) and a thermal conductivity enhancing filler (spherical alumina, D50 particle size of 3 μm) with a mass ratio of 0.5:1; other conditions are the same as those in Embodiment 1.

[0105] Embodiment 15

[0106] This embodiment provides a vertically oriented structure thermally conductive electromagnetic shielding material and a preparation method thereof. The difference from Embodiment 1 is only that the fillers are adjusted to a thermally conductive filler (carbon fiber, average length of 250 μm, diameter of 10 μm) and a thermal conductivity enhancing filler (spherical alumina, D50 particle size of 3 μm) with a mass ratio of 8:1; other conditions are the same as those in Embodiment 1.

[0107] Embodiment 16

[0108] This embodiment provides a vertically oriented structure thermally conductive electromagnetic shielding material and a preparation method thereof. The vertically oriented structure thermally conductive electromagnetic shielding material includes a thermally conductive composite layer and an electromagnetic shielding film layer; the thermally conductive composite layer and the electromagnetic shielding film layer are alternately arranged to form a layered structure, and the orientation direction is the same as the thickness direction;

[0109] The preparation raw materials of the thermally conductive composite layer are a filler and a silicone resin with a mass ratio of 4:1; the filler is a thermally conductive filler (carbon fiber, average length of 250 μm, diameter of 10 μm), a thermal conductivity enhancing filler (spherical alumina, D50 particle size of 3 μm), and a conductive filler (flake silver powder, D50 particle size of 5 μm) with a mass ratio of 2:1:1.

[0110] The above silicone resin is composed of polydimethylsiloxane (manufacturer: Dow Chemical Company, grade: Dow Corning SYLGARD TM 184 Silicone Elastomer Base) and a curing agent (manufacturer: Dow Chemical Company, grade: Dow Corning SYLGARD TM 184 Silicone Elastomer Curing Agent) with a mass ratio of 30:1.

[0111] The preparation method of the vertically oriented structure thermally conductive electromagnetic shielding material is as follows:

[0112] (1) Mix polydimethylsiloxane and a curing agent in a mass ratio of 30:1, disperse them evenly through a vacuum mixer to form a silicone resin, then blend and stir evenly with a filler, and obtain a thermally conductive composite material with a thickness of 0.8 mm through extrusion molding. Cut the thermally conductive composite material into sheets of 40×80 mm 2 to obtain a thermally conductive composite material of 40×80×0.8 mm 3 ;

[0113] (2) Alternately stack the 40×80×0.8 mm 3 thermally conductive composite material prepared in step (1) and an electromagnetic shielding film (tinned fiber cloth, manufacturer: Shenzhen Zhuohan Material Technology Co., Ltd., thickness 0.05 mm) of 40×80×0.05 mm 3 in a cuboid mold. A total of 41 sheets of thermally conductive composite material are stacked, and a total of 40 sheets of tinned fiber cloth are stacked. Then, use a hot pressing process to press the thermally conductive composite material and the tinned fiber cloth together. The pressure of hot pressing is 2 MPa, the temperature is 120 °C, and the time is 30 min. Then transfer it to an oven at 130 °C for curing for 2 h. After curing is completed, cut it along the direction perpendicular to the orientation to obtain a vertically oriented structure thermally conductive electromagnetic shielding material with a thickness of 2 mm.

[0114] Example 17

[0115] This example provides a vertically oriented structure thermally conductive electromagnetic shielding material and its preparation method. The vertically oriented structure thermally conductive electromagnetic shielding material includes a thermally conductive composite material layer and an electromagnetic shielding film layer; the thermally conductive composite material layer and the electromagnetic shielding film layer are alternately arranged to form a layered structure, and the orientation direction is the same as the thickness direction;

[0116] The preparation raw materials of the thermally conductive composite material layer are a filler and a silicone resin (two-component methyl vinyl siloxane, manufacturer: Dow Chemical Company, grade: SYLGARD TM 527) in a mass ratio of 4:1; the filler is a thermally conductive filler (carbon fiber, average length 250 μm, diameter 10 μm), a thermally conductive enhancing filler (spherical alumina, D50 particle size 3 μm), and a conductive filler (flake silver powder, D50 particle size 5 μm) in a mass ratio of 2:1:1.

[0117] The preparation method of the vertically oriented structure thermally conductive electromagnetic shielding material is as follows:

[0118] (1) Mix component A and component B of the two-component methyl vinyl siloxane in a mass ratio of 1:1, and disperse them evenly through a vacuum mixer to form a silicone resin. Then, blend it with the filler and stir evenly. Obtain a thermal conductive composite material with a thickness of 0.5 mm through a roll press. Cut the thermal conductive composite material into sheets of 40×80 mm 2 to obtain a thermal conductive composite material of 40×80×0.5 mm 3 ;

[0119] (2) Alternately stack the 40×80×0.5 mm 3 thermal conductive composite material prepared in step (1) and a 40×80×0.05 mm 3 electromagnetic shielding film (tinned fiber cloth, manufacturer: Shenzhen Zhuohan Material Technology Co., Ltd., thickness 0.05 mm) in a cuboid mold. A total of 61 sheets of the thermal conductive composite material are stacked, and a total of 60 sheets of the tinned fiber cloth are stacked. Then, use a hot pressing process to press the thermal conductive composite material and the tinned fiber cloth together. The pressure of the hot pressing is 2 MPa, the temperature is 120 °C, and the time is 30 min. Then, transfer it to an oven at 130 °C for curing for 2 h. After curing, cut it along the direction perpendicular to the orientation to obtain a vertically oriented structure thermal conductive electromagnetic shielding material with a thickness of 2 mm.

[0120] Comparative Example 1

[0121] This comparative example provides a thermal conductive electromagnetic shielding material and its preparation method. The difference from Example 1 is only that no thermal conductive filler is added to the filler, and the filler is a thermal conductive reinforcing filler (spherical alumina, D50 particle size of 3 μm) and a conductive filler (flake silver powder, D50 particle size of 5 μm) with a mass ratio of 3:1.

[0122] The preparation method of the thermal conductive electromagnetic shielding material is as follows:

[0123] (1) Mix component A and component B of the two-component methyl vinyl siloxane in a mass ratio of 1:1, and disperse them evenly through a vacuum mixer to form a silicone resin. Then, blend it with the filler and stir evenly. Obtain a thermal conductive composite material with a thickness of 1 mm through extrusion molding. Cut the thermal conductive composite material into sheets of 40×80 mm 2 to obtain a thermal conductive composite material of 40×80×1 mm 3 ;

[0124] (2) The 40×80×1 mm 3 thermal conductive composite material prepared in step (1) and a 40×80×0.05 mm 3The electromagnetic shielding films (tinned fiber cloth, Shenzhen Zhuohan Material Technology Co., Ltd., thickness 0.05 mm) are alternately laminated in a cuboid mold. A total of 31 sheets of the thermally conductive composite material are laminated, and a total of 30 sheets of the tinned fiber cloth are laminated. Then, the laminated thermally conductive composite material and the tinned fiber cloth are pressed together by a hot pressing process. The pressure of the hot pressing is 2 MPa, the temperature is 120 °C, and the time is 20 min. Then, it is transferred to an oven at 130 °C for curing for 2 h. After curing is completed, it is cut along the direction perpendicular to the orientation to obtain a thermally conductive electromagnetic shielding material with a thickness of 2 mm.

[0125] Other conditions are the same as those in Example 1.

[0126] Comparative Example 2

[0127] This comparative example provides a thermally conductive electromagnetic shielding material and a preparation method thereof. The difference from Example 1 is only that the thermally conductive electromagnetic shielding material does not include an electromagnetic shielding film layer;

[0128] The preparation method of the thermally conductive electromagnetic shielding material is as follows:

[0129] (1) The A component and the B component of the two-component methyl vinyl silicone are mixed in a mass ratio of 1:1, and are dispersed evenly by a vacuum mixer to form a silicone resin. Then, it is blended and stirred evenly with a filler, and a thermally conductive composite material with a thickness of 1 mm is obtained by extrusion molding. The thermally conductive composite material is cut into sheets with a size of 40×80 mm 2 to obtain a thermally conductive composite material with a size of 40×80×1 mm 3 ;

[0130] (2) The 40×80×1 mm 3 thermally conductive composite material prepared in step (1) is laminated in a cuboid mold. A total of 35 sheets of the thermally conductive composite material are laminated. Then, the laminated thermally conductive composite material is pressed together by a hot pressing process. The pressure of the hot pressing is 2 MPa, the temperature is 120 °C, and the time is 20 min. Then, it is transferred to an oven at 130 °C for curing for 2 h. After curing is completed, it is cut along the direction perpendicular to the orientation to obtain a thermally conductive electromagnetic shielding material with a thickness of 2 mm.

[0131] Other conditions are the same as those in Example 1.

[0132] The following tests are carried out on the vertically oriented structure thermally conductive electromagnetic shielding materials provided in the above Examples 1 to 17 and the thermally conductive electromagnetic shielding materials provided in Comparative Examples 1 to 2:

[0133] (1) Out-of-plane thermal conductivity: Tested with reference to ASTM D5470-2017. An out-of-plane thermal conductivity ≥ 5 W / m -1 K -1 is regarded as qualified;

[0134] (2) Near-field shielding effectiveness: It is tested using a near-field scanning system. The distance between the test probe and the electromagnetic wave radiation source is ≤ λ / 2π (λ is the wavelength corresponding to the test frequency). An excitation source is provided for the chip or device through a vector network analyzer, and the radiation field strength of the chip or device test model with the shielding material is measured. The near-field shielding effectiveness is obtained through calculation. The specific test method can refer to relevant literature (Hyun Ho Park. Near-Field Shielding Analysis of Conformal Coating Materials for Integrated Circuits. IEEE Transactions on Electromagnetic Compatibility, 2022, 64(5), 1622-1631); the width of the metal frame of the test model is 2 mm. As Figure 4 shown, the vertically oriented structure thermally conductive electromagnetic shielding material 1 is in contact with the metal frame 2. The number of layers of the electromagnetic shielding film layer at the contact position 3 between the metal frame and the vertically oriented structure thermally conductive electromagnetic shielding material is 1 to 3. The number of layers is related to the thicknesses of the thermally conductive composite material and the electromagnetic shielding film during the preparation process. A near-field shielding effectiveness ≥ 44 dB is considered qualified.

[0135] The test results are shown in Table 1 below:

[0136] Table 1

[0137]

[0138]

[0139] As can be seen from the content of Table 1, the out-of-plane thermal conductivity of the vertically oriented structure thermally conductive electromagnetic shielding materials provided in Examples 1 to 17 is ≥ 5 W / m -1 K -1 , and the near-field shielding effectiveness is ≥ 44 dB.

[0140] Compared with Example 1, if the ratio of the mass of the thermally conductive filler, the mass of the thermally conductive enhancing filler to the total mass of the conductive filler and / or magnetic filler is not within the range of (2 - 3):(1 - 1.5):1 (Example 4) or (Example 5), the comprehensive performance of the prepared vertically oriented structure thermally conductive electromagnetic shielding material will be reduced, and it is difficult to obtain both a high out-of-plane thermal conductivity and a high near-field shielding effectiveness at the same time. From this, it can be seen that by controlling the ratio of the mass of the thermally conductive filler, the mass of the thermally conductive enhancing filler to the total mass of the conductive filler and / or magnetic filler within the range of (2 - 3):(1 - 1.5):1 in the present invention, the performance of the prepared vertically oriented structure thermally conductive electromagnetic shielding material is better.

[0141] Compared with Example 1, if the length of the carbon fiber is too short (Example 6), the out-of-plane thermal conductivity of the prepared vertically oriented structure thermally conductive electromagnetic shielding material will decrease; if the length of the carbon fiber is too long (Example 7), the dispersibility of the carbon fiber filler in the thermally conductive composite material is poor, resulting in poor fluidity during the orientation forming process, a decrease in processability, a decrease in the bonding effect between the silicone resin and the filler, and the appearance of pore defects in the thermally conductive composite material. Electromagnetic waves will leak from the pores, resulting in a decrease in the electromagnetic shielding performance of the vertically oriented structure thermally conductive electromagnetic shielding material. It can be seen that in the present invention, when the length of the carbon fiber is in the range of 100-500 μm, the performance of the prepared vertically oriented structure thermally conductive electromagnetic shielding material is better.

[0142] Compared with Example 1, if the silver powder is replaced with copper powder (Example 10), the out-of-plane thermal conductivity of the prepared vertically oriented structure thermally conductive electromagnetic shielding material changes little, and the electromagnetic shielding performance decreases slightly, but still remains at a relatively high level.

[0143] Compared with Example 1, if the conductive filler is replaced with a magnetic filler (Example 11), the out-of-plane thermal conductivity of the prepared vertically oriented structure thermally conductive electromagnetic shielding material changes little, but the near-field shielding efficiency decreases significantly. It can be seen that in the present invention, the filler is a combination of a thermally conductive filler, a thermally conductive enhancing filler, and a conductive filler, and the performance of the prepared vertically oriented structure thermally conductive electromagnetic shielding material is better.

[0144] Compared with Example 1, if no conductive filler is added (Example 12), the out-of-plane thermal conductivity of the prepared vertically oriented structure thermally conductive electromagnetic shielding material increases, and the near-field shielding efficiency decreases.

[0145] Compared with Example 12, if the mass ratio of the thermally conductive filler to the thermally conductive enhancing filler is too low (Example 14), it is difficult to form the oriented structure of the prepared vertically oriented structure thermally conductive electromagnetic shielding material, and the out-of-plane thermal conductivity of the composite material decreases; if the mass ratio of the thermally conductive filler to the thermally conductive enhancing filler is too high (Example 15), the viscosity is high and the fluidity is poor during the orientation forming process of the thermally conductive composite material, the processability decreases, the silicone resin cannot fully bond and coat the filler, and defects are likely to appear, resulting in a decrease in the electromagnetic shielding performance of the vertically oriented structure thermally conductive electromagnetic shielding material; it can be seen that the mass ratio of the thermally conductive filler to the thermally conductive enhancing filler is preferably (1-4):1, and the performance of the prepared vertically oriented structure thermally conductive electromagnetic shielding material is better.

[0146] Compared with Example 1, if no thermally conductive filler is added (Comparative Example 1), both the out-of-plane thermal conductivity and the near-field shielding efficiency of the prepared thermally conductive electromagnetic shielding material decrease, and the out-of-plane thermal conductivity decreases significantly.

[0147] Compared with Example 1, if the thermally conductive electromagnetic shielding material does not include an electromagnetic shielding film layer (Comparative Example 2), the near-field shielding effectiveness of the prepared thermally conductive electromagnetic shielding material will decrease significantly.

[0148] The applicant declares that the process method of the present invention is illustrated by the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent substitution of the raw materials selected for the present invention, the addition of auxiliary components, the selection of specific methods, etc. all fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A vertically oriented structured thermal conductive electromagnetic shielding material, characterized in that: The vertically oriented structured heat-conducting electromagnetic shielding material comprises a heat-conducting composite material layer and an electromagnetic shielding film layer; the heat-conducting composite material layer and the electromagnetic shielding film layer are alternately arranged to form a layered structure, and the orientation direction is the same as the thickness direction; The raw materials for preparing the thermal conductive composite material layer include silicone resin and filler; the filler includes thermal conductive filler.

2. The vertically oriented structured thermal conductive electromagnetic shielding material according to claim 1, characterized in that: The outermost layers on both sides of the vertically oriented structured thermal conductive electromagnetic shielding material that are alternately arranged are thermal conductive composite material layers; Preferably, the silicone resin comprises a thermosetting silicone resin; Preferably, the thermosetting silicone resin includes any one of polyalkyl silicone resin, polyaryl silicone resin or polyalkylaryl silicone resin or a combination of at least two thereof; Preferably, the mass ratio of the filler to the silicone resin is (3-5):

1.

3. The vertically oriented structured thermal conductive electromagnetic shielding material according to claim 1 or 2, characterized in that: The thermally conductive filler includes a one-dimensional thermally conductive filler and / or a two-dimensional thermally conductive filler; Preferably, the thermally conductive filler has electrical conductivity; Preferably, the thermally conductive filler comprises any one of carbon fiber, graphite sheet, graphene, carbon nanotube or surface metallized filler or a combination of at least two thereof; Preferably, the surface metallized filler includes any one of surface metal-coated graphite, surface metal-coated carbon fiber or surface metal-coated carbon nanotube, or a combination of at least two thereof; Preferably, the average length of the carbon fiber is 50 to 3000 μm, more preferably 100 to 500 μm; Preferably, the filler further comprises a thermally conductive enhanced filler; Preferably, the thermal conductivity enhancing filler includes any one of aluminum oxide, silicon carbide, silicon oxide, aluminum nitride, magnesium oxide or zinc oxide, or a combination of at least two thereof.

4. The vertically oriented structured thermal conductive electromagnetic shielding material according to claim 3, characterized in that: The mass ratio of the thermal conductive filler to the thermal conductive enhancing filler is (0.5-8):1, and more preferably (1-4):

1.

5. The vertically oriented structured thermal conductive electromagnetic shielding material according to any one of claims 1 to 3, characterized in that: The filler also includes conductive filler and / or magnetic filler; Preferably, the conductive filler comprises any one of carbon black, gold powder, silver powder, copper powder, nickel powder, aluminum powder, silver-coated copper powder, silver-coated aluminum powder, silver-coated nickel powder, surface-plated metal glass fiber or surface-plated metal glass microbeads, or a combination of at least two thereof; Preferably, the magnetic filler comprises any one of nickel powder, ferrite powder, cobalt powder, iron nitride powder or carbonyl iron powder, or a combination of at least two thereof; Preferably, the ratio of the mass of the thermally conductive filler, the mass of the thermally conductive enhancing filler to the total mass of the conductive filler and / or the magnetic filler is (1-8):(0.5-4):1, and more preferably (2-3):(1-1.5):

1.

6. The vertically oriented structured thermal conductive electromagnetic shielding material according to any one of claims 1 to 5, characterized in that: The electromagnetic shielding film layer comprises an electromagnetic shielding material having a mesh or hole structure; Preferably, the electromagnetic shielding material having a mesh or hole structure comprises a metal mesh, a woven metal fiber cloth or a fiber cloth with a metal plated surface; Preferably, the metal in the metal mesh, woven metal fiber cloth or fiber cloth with metal plated on the surface independently comprises pure metal or alloy; Preferably, the number of thermally conductive composite material layers in the vertically oriented structured thermally conductive electromagnetic shielding material is ≥5, and the number of electromagnetic shielding film layers is ≥4.

7. A method for preparing a vertically oriented structured thermally conductive electromagnetic shielding material according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: (1) mixing an organic silicone resin and a filler, and obtaining a thermally conductive composite material by an orientation molding process; (2) Alternately stacking, pressing, and curing the thermally conductive composite material and the electromagnetic shielding film obtained in step (1) to obtain the vertically oriented thermally conductive electromagnetic shielding material.

8. The preparation method according to claim 7, characterized in that: The orientation molding process in step (1) includes extrusion molding or roll molding; Preferably, the pressing in step (2) comprises roller pressing or hot pressing; Preferably, the curing in step (2) comprises thermal curing; Preferably, after the curing in step (2), the step further includes cutting along a direction perpendicular to the orientation.

9. The preparation method according to claim 7 or 8, characterized in that: The thickness of the thermally conductive composite material in step (1) is 0.1 to 2 mm; Preferably, the thickness of the electromagnetic shielding film in step (2) is 0.01 to 0.2 mm; Preferably, the thickness of the vertically oriented structured thermal conductive electromagnetic shielding material is 0.1 to 50 mm, more preferably 0.1 to 5 mm, and even more preferably 0.5 to 3 mm.

10. Use of the vertically oriented structured thermal conductive electromagnetic shielding material according to any one of claims 1 to 6 in electronic packaging.

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