An electromagnetic shielding and heat-conducting multi-layer material and a preparation method thereof

Abstract

An electromagnetic shielding and heat-conducting multi-layer material and a preparation method thereof. The multi-layer material includes an electric field shielding layer, an epoxy heat-conducting adhesive layer, and a magnetic field shielding layer. The electric field shielding layer includes a copper foil layer with a thickness of 5-12 μm. The magnetic field shielding layer has a thickness of 1-3 mm and includes a resin matrix A and carbon fiber cloth. By weight, the resin matrix A includes: 100 parts of bismaleimide resin, 60-68 parts of 3,3-diallylbisphenol A, 32-40 parts of triallyl isocyanurate, 18-20 parts of N,N-dimethylformamide, 100-160 parts of magnetic field shielding filler, 8-10 parts of di-sec-octyl phthalate, and 0.3-0.8 parts of cobalt naphthenate. The magnetic field shielding filler is compounded by nano-manganese zinc ferrite and micron nickel powder in a mass ratio of (80-120):(30-40). The electromagnetic shielding and heat-conducting multi-layer material of the present invention has both electric field and magnetic field shielding functions and is particularly suitable for high magnetic field and high electric field application environments.

Description

Technical Field

[0001] The present invention belongs to the technical field of formula design and preparation and molding of electromagnetic shielding functional composite materials, and particularly relates to an electromagnetic shielding and heat-conducting multi-layer material and a preparation method thereof. Background Art

[0002] Sensors are the antennas of the digital power grid. By monitoring the temperature changes of power equipment, the humidity of the surrounding environment, and the changes in air pressure in real time, the usage conditions, aging degree, and failure risks of the equipment are estimated to improve the operation stability of the power system. Traditional sensors are all used in non-complex electromagnetic environments, but faults often occur at the high-voltage end of power equipment. Therefore, how to achieve stable operation of sensors at the high-voltage end is crucial. Due to the characteristics of strong magnetic fields and high electric fields at the high-voltage end, it is an inevitable and effective choice to conduct electromagnetic shielding packaging for sensors.

[0003] Conventional electromagnetic shielding materials are often used to shield transmission signals, radar waves, etc., which are very different from the actual current usage requirements. Moreover, a continuous metal shell will form relatively large eddy current losses under the action of a strong magnetic field, resulting in heat generation and affecting the stable operation and test accuracy of sensors. Therefore, it is necessary to design a new shielding structure according to the usage environment characteristics of the high-voltage end of power equipment.

[0004] Patent CN103144377A discloses a composite electromagnetic shielding copper foil substrate with a high heat-conducting effect and a manufacturing method thereof. The composite electromagnetic shielding copper foil substrate is composed of a copper foil layer, an insulating polymer layer, a heat-dissipating adhesive layer, a metal shielding layer, a conductive adhesive layer, and a sixth stack layer stacked in sequence. The sixth stack layer is a metal layer or a release material layer. The present invention simultaneously has the effects of high heat dissipation and electromagnetic shielding, and can not only be applied to electronic products with relatively strict electromagnetic compatibility requirements, but also solves the problem that the heat generated by electronic products cannot be removed in time. It replaces the traditional mode of using a copper foil substrate in combination with a shielding film and heat-dissipating electronic components, saves material costs by using a composite material to replace the combination of multiple original materials, reduces the product thickness, saves the production process, and can better improve the overall dimensional stability of the product substrate. However, the heat-conducting performance of this invention is poor, and the heat generated during the operation of the sensor affects the shielding effect, and its electromagnetic shielding performance is difficult to meet the application of sensors in high magnetic field and high electric field environments.

[0005] Patent CN204589059U discloses a shielding and wave-absorbing tape, which includes a protective layer, a composite material layer, a wave-absorbing layer and a release material layer. The protective layer is a layer of mesh polyimide film, and a layer of resin film layer is covered on the outer surface of this mesh polyimide film, and a layer of graphite fiber layer is covered on the inner surface. The composite material layer is formed on the inner side of the protective layer through a soft silicone layer. Its main structure is a layer of aluminum foil, and 3-4 copper foils parallel to the tape surface are formed on the surface of this aluminum foil. The wave-absorbing layer is formed on the outer side of the aluminum foil of the composite material layer, and a layer of silane coupling agent layer is formed on the wave-absorbing layer, and a layer of acrylate adhesive layer and a layer of release layer are formed into one body on the surface of the silane coupling agent layer. This utility model has simple process, convenient processing, good magnetic shielding effect, and is applicable to electromagnetic shielding of high-frequency electric fields and low-frequency magnetic fields. However, the large-area metal layer of this utility model will form relatively large eddy current losses under the action of a strong magnetic field, resulting in heat generation and affecting the stable operation and test accuracy of the sensor.

[0006] Therefore, how to obtain an electromagnetic shielding and heat-conducting material with both electric field and magnetic field shielding functions and heat-conducting performance, so that it can effectively protect sensitive measuring devices in high-magnetic-field and high-electric-field application environments has become an urgent technical problem in this field. Summary of the Invention

[0007] Aiming at the defects existing in the above-mentioned prior art, the purpose of the present invention is to provide an electromagnetic shielding and heat-conducting multi-layer material and its preparation method. The electromagnetic shielding and heat-conducting multi-layer material prepared by the present invention has both electric field and magnetic field shielding functions and good heat-conducting performance, and is particularly suitable for high-magnetic-field and high-electric-field application environments.

[0008] Specifically, the present invention provides an electromagnetic shielding and heat-conducting multi-layer material, which successively includes an electric field shielding layer, an epoxy heat-conducting adhesive layer and a magnetic field shielding layer;

[0009] The electric field shielding layer includes a copper foil layer, and the thickness of the copper foil layer is 5-12 μm;

[0010] The thickness of the magnetic field shielding layer is 1-3 mm, and it includes a resin matrix A and carbon fiber cloth distributed therein; calculated by weight, the resin matrix A includes the following components:

[0011]

[0012] The magnetic field shielding filler is compounded by nano-manganese zinc ferrite and micron nickel powder in a mass ratio of (80-120):(30-40).

[0013] In the present invention, the electric field shielding layer and the magnetic field shielding layer are joined by an epoxy thermal conductive adhesive, and good electromagnetic shielding and thermal conductivity are obtained simultaneously. Among them, in the magnetic field shielding layer, a compound of magnetic field shielding fillers with different particle sizes and carbon fiber cloth are particularly used, which can provide sufficient magnetic field shielding performance and mechanical properties, and form an all-round protection and shielding for its encapsulated shielding object. Among them, the carbon fiber cloth, nano-manganese zinc ferrite and micron nickel powder are preferably surface-treated to improve their compatibility with the resin matrix and the dispersibility of nano-manganese zinc ferrite and micron nickel powder. The surface treatment can be plasma surface activation treatment or surface treatment with a coupling agent. Relatively speaking, for nano-manganese zinc ferrite and micron nickel powder, plasma surface activation treatment is more preferred, and the specific treatment methods are as follows:

[0014] Control the vacuum degree to be 1×10 -2 -10×10 -2 Pa, heat up to 80 - 120 °C, introduce argon gas, and perform surface activation treatment on the surface of nano-manganese zinc ferrite and / or micron nickel powder by argon plasma under vacuum, and the treatment time is 1 - 5 min.

[0015] Adopting plasma surface activation treatment, the steps are simple, no other treatment agents need to be introduced, the implementation and collection are convenient, and there is almost no loss of nano-manganese zinc ferrite and micron nickel powder.

[0016] Furthermore, the electric field shielding layer further includes a polyimide base film, and the polyimide base film and the copper foil layer are joined through a heat-resistant adhesive layer; the thickness of the electric field shielding layer is 20 - 100 μm.

[0017] Furthermore, the thickness of the heat-resistant adhesive layer is 5 - 25 μm, and by weight, its raw materials include the following components:

[0018]

[0019] The electric field shielding layer formed by the above composite layer can provide excellent electric field shielding performance by using the copper foil layer therein. And by using the polyimide base film and the heat-resistant adhesive layer, on the one hand, it can provide sufficient support during the surface treatment of the copper foil to prevent its breakage or uneven treatment; on the other hand, during the subsequent forming and use processes, it can better avoid the ultra-thin copper foil layer from being damaged, providing stable and long-term electric field shielding performance for the materials of the present invention.

[0020] The surface of the copper foil layer has a plurality of bumps, the diameter of the bumps is 5 - 50 μm, the spacing of the bumps is 50 - 100 μm, and the density of the bumps is 100 - 500 pieces / mm 2. In pattern design, the thickness of the aforementioned copper foil layer corresponds to the thickness from the highest point of the copper foil bump to the other surface of the copper foil without bumps. Optionally, if bump patterning is designed on both sides of the copper foil layer, the thickness of the copper foil layer represents the vertical distance between the highest points of the bumps on both sides of the copper foil. It can be seen that through the above-mentioned patterning treatment, the actual copper content of the copper foil is reduced, the contact area of the copper foil is reduced on the basis of the original surface, and the eddy current loss is reduced. The use of (semi) spherical, cylindrical or truncated cone-shaped bump structures can better reduce the risk of local discharge and enhance the electromagnetic shielding effect.

[0021] Preferably, patterning is performed on the surface of the copper foil layer by laser micro-etching technology, which specifically includes the following steps:

[0022] S1: Use NaClO2 and sodium hydroxide to prepare the surface oxidation solution, wherein the concentration of NaClO2 is 60-90g / L and the concentration of NaOH is 20-30g / L;

[0023] S2: using the surface oxidation liquid to perform oxidation treatment on the upper surface of the copper foil layer, the treatment temperature is 70±5°C, and the time is 5-15min; the surface of the copper foil after treatment presents a black oxide layer;

[0024] S3: micro-etching with 1000-1100nm fiber laser; preferably, the laser parameters are: scanning rate 300-500mm / s, power 20-25W, frequency 30-50kHz, and the diameter of the light spot focused by the lens is 5-30μm;

[0025] S4: Soak the copper foil layer in dilute hydrochloric acid with a mass fraction of 5-8%, rinse it repeatedly with deionized water, and dry it.

[0026] NaClO2 is a substance with strong oxidizing property, which releases ClO2 gas when encountering acid. The present invention adds sodium hydroxide to adjust the acid-base environment of the reaction. Under alkaline conditions and appropriate heating conditions, it is more conducive to the decomposition of the intermediate product copper hydroxide into copper oxide, and the positive chlorine ions capture the outer electrons of the copper atoms, oxidize the surface, and generate a black copper oxide film. However, the concentration of NaClO2 should not be too high. Excessive oxidation at too high a concentration leads to insufficient surface roughness, resulting in a decrease in light absorption rate, and insufficient adhesion between the oxide layer and the lower copper layer, which is easy to peel off when the laser is applied, so the present invention selects NaClO2 concentration of 60-90g / L, preferably 70-80g / L.

[0027] After laser etching, dilute hydrochloric acid is used to remove the black copper oxide on the surface, as well as impurities such as oxides formed during etching, effectively cleaning the surface of the copper foil. Dilute hydrochloric acid can be used to soak the copper foil several times until the black color of the copper foil fades and the soaked dilute hydrochloric acid changes from green (high copper chloride content), blue (low copper chloride content) to colorless.

[0028] The present invention prepares a patterned copper foil by a method combining physical and chemical methods. Compared with traditional etching techniques, it uses less corrosive materials, mild conditions, has a higher precision in laser micro-etching, is easy to control, and then is cleaned with hydrochloric acid to effectively remove oxides without damaging the copper foil, resulting in a fine surface structure of the copper foil.

[0029] Further, the multi-layer material further includes a heat-conducting composite layer with a thickness of 1.0 - 2.0 mm, which is located on the surface of the magnetic field shielding layer opposite to the electric field shielding layer, and includes a resin matrix B, micron-sized boron nitride, and glass fiber cloth; the mass ratio of the micron-sized boron nitride to the resin matrix B is (15 - 20):100. Among them, the particle size of the boron nitride particles is 0.5 - 1.5 μm. The glass fiber cloth is preferably an alkali-free glass fiber cloth with a grammage of 100 - 120 g / m 2 5.

[0030] Further, by weight, the resin matrix B includes the following components:

[0031]

[0032] Further, the preparation method of the heat-conducting composite layer includes the following steps:

[0033] S1: Prepare an ethanol aqueous solution of a silane coupling agent with a mass fraction of 1 - 3%, in which ethanol and pure water are mixed according to a mass ratio of 1:(7 - 10), and then acetic acid is added to adjust the pH value to 3 - 4.5, and pre-hydrolyze at 45 - 75 °C for standby;

[0034] S2: Add boron nitride particles with a particle size of 0.5 - 1.5 μm to the pre-hydrolyzed silane coupling agent solution, mix and react for 2 - 4 h, vacuum filter, and wash the obtained solid repeatedly with absolute ethanol, and dry at 50 - 65 °C and cool to obtain surface-treated boron nitride particles;

[0035] S3: Add 30 - 70% of the surface-treated boron nitride particles to the resin matrix B, mix evenly to obtain a heat-conducting adhesive solution;

[0036] S4: Disperse the remaining 30 - 70% of the surface-treated boron nitride particles in a butanone solution with a solid content of 30 - 35 wt%; vacuum filter and dry to make the boron nitride particles adhere to the glass fiber cloth;

[0037] S5: Coat the heat-conducting adhesive solution obtained in step S3 on the glass fiber cloth in step S4, and pre-cure to obtain a heat-conducting composite layer prepreg;

[0038] S6: Cure the heat-conducting composite layer prepreg to obtain a heat-conducting composite layer.

[0039] Among them, the resin matrix B is prepared through the following steps:

[0040] Step 1: Blend bismaleimide resin, 3,3-diallylbisphenol A, and triallyl isocyanurate, react at 95 - 105°C for 10 - 20 min, then raise the temperature to 120 - 130°C and react for 15 - 30 min;

[0041] Step 2: Add vinyltoluene, cashew phenol, diisopropylbenzene peroxide, and cobalt naphthenate, mix evenly, and discharge at room temperature.

[0042] Furthermore, the magnetic field shielding layer and the thermal conductive composite layer are an integral structure and are obtained through the following forming steps:

[0043] Apply the sizing solution of the resin matrix A of the magnetic field shielding layer by sizing and drying onto the carbon fiber cloth to obtain the magnetic field shielding layer prepreg; among them, the carbon fiber cloth preferably has a gram weight of 70 - 100 g / m 2 ; Specifically, it includes the following steps: 1) Immerse the carbon fiber cloth in the sizing tank for 5 - 10 sec, and the double-roll reverse sizing pressure is 0.3 - 0.8 MPa; 2) Step-by-step drying: dry at 95 - 105°C for 10 sec, 140 - 160°C for 10 sec, and 120 - 140°C for 10 sec;

[0044] Stack the magnetic field shielding layer prepreg and the thermal conductive composite layer prepreg and hot press them into an integral structure; the specific hot pressing process is as follows: 1) Preheat at 130 - 150°C for 25 - 30 min, apply a pressure of 3 ± 0.5 MPa, after 8 - 15 min, raise the temperature to 160 - 180°C, and raise the pressure to 5 ± 0.5 MPa, and hold for 2.5 - 3.5 h; 2) Raise the temperature to 195 - 205°C, raise the pressure to 10 ± 0.5 MPa, and hold for 1.5 - 2.5 h. The shape of the hot press mold can be selected according to the application scenario. When used for encapsulating components, the corresponding encapsulation space can be pressed out.

[0045] On the other hand, the present invention also provides a preparation method for the electromagnetic shielding and thermal conductive multi-layer material for the aforementioned electromagnetic shielding and thermal conductive multi-layer material, including the following steps:

[0046] S1: Prepare the magnetic field shielding layer

[0047] S1.1: Prepare the magnetic field shielding sizing solution: Mix the components of the resin matrix A evenly according to the ratio. Among them, the magnetic field shielding fillers are added in batches at (40 - 60%) : (20 - 30%) : (20 - 30%) of their total mass; and it is preferably to add micron-sized nickel powder first, and then add nano-manganese zinc ferrite, which is beneficial for the nano-fillers to enter and disperse in the gaps of the micron-fillers, weakening the agglomeration tendency of the nano-fillers;

[0048] S1.2: Immerse the carbon fiber cloth into the magnetic field shielding adhesive solution in the adhesive tank, apply the adhesive with double rollers in reverse direction, and obtain the prepreg of the magnetic field shielding layer after drying.

[0049] S2: Prepare the epoxy thermal conductive adhesive: The epoxy thermal conductive adhesive includes component A containing epoxy resin and component B containing epoxy curing agent.

[0050] S3: Mix component A and component B of the epoxy thermal conductive adhesive prepared in S2 evenly, apply it on the surface of the copper foil layer within 10 - 20 minutes, stack the surface of the copper foil layer with the epoxy thermal conductive adhesive on the magnetic field shielding layer prepreg, and hot press to form the electromagnetic shielding and thermal conductive multi-layer material.

[0051] The above method provides a way to co-cure the epoxy thermal conductive adhesive and the magnetic field shielding layer, improving the interlayer bonding force and the durability of the product.

[0052] Further, before step S2, it also includes the step of preparing the prepreg of the thermal conductive composite layer. The thermal conductive composite layer includes resin matrix B, micron-sized boron nitride, and glass fiber cloth. And step S3 includes stacking the surface of the copper foil layer with the epoxy thermal conductive adhesive on the magnetic field shielding layer prepreg and the thermal conductive composite layer prepreg in sequence, and hot pressing to form the electromagnetic shielding and thermal conductive multi-layer material. That is, the electromagnetic shielding and thermal conductive multi-layer material generally has the following structure: electric field shielding layer (including copper foil layer) | epoxy thermal conductive adhesive | magnetic field shielding layer | thermal conductive composite layer.

[0053] When a thermal conductive composite layer is further arranged outside the magnetic field shielding layer, both the thermal conductive composite layer and the magnetic field shielding layer contain a large amount of bismaleimide resin. By using hot pressing, their compatibility is fully demonstrated, and an integrated structure with a blurred interface can be formed, which is beneficial to the improvement of mechanical properties and thermal conductivity. For the step of preparing the prepreg of the thermal conductive composite layer, the composition ratio, preparation method, etc. of the prepreg of the thermal conductive composite layer described above can be referred to. Then stack the surface of the copper foil layer with the epoxy thermal conductive adhesive on the magnetic field shielding layer prepreg and the thermal conductive composite layer prepreg in sequence, and hot press the whole to form the electromagnetic shielding and thermal conductive multi-layer material with better thermal conductivity.

[0054] In the third aspect, in order to expand the use of the aforementioned electromagnetic shielding and thermal conductive multi-layer material, the present invention also provides a detection device encapsulated with the electromagnetic shielding and thermal conductive multi-layer material. The detection device only needs to place its detection probe outside the encapsulation formed by the electromagnetic shielding and thermal conductive multi-layer material. This structure neither affects the detection sensitivity and convenience of the detection probe, nor can it protect the internal components of the detection device from the interference and damage of external high electric fields and high magnetic fields.

[0055] The advantages of the present invention are specifically as follows:

[0056] 1) The present invention adopts a laminated structure of an electric field shielding layer, a magnetic field shielding layer, and a heat conduction layer to form a comprehensive multi-layer material with composite shielding functions such as electric field, magnetic field, and heat conduction. Moreover, the package formed by this multi-layer material has good shielding performance and mechanical properties, and can be used to protect precision measurement components such as detection devices, especially suitable for precision temperature and humidity measurement components in high magnetic field and high electric field working scenarios.

[0057] 2) The present invention also has a heat conduction composite layer that can be integrally formed with the magnetic field shielding layer outside the magnetic field shielding layer. On the basis of the already provided heat conduction layer, in addition to being able to quickly export the heat inside the package, it is also particularly beneficial to balance the temperature of the internal components while exporting the internal heat, avoiding damage due to insufficient local heat conduction.

[0058] 3) The present invention uses polyimide with a high flame retardant grade as the base film, and at the same time, flame retardants can be added to both the heat-resistant adhesive layer and the heat-conducting adhesive to further improve the flame retardant performance of the multi-layer material, reaching the UL94V-0 grade;

[0059] 4) In view of the composition and performance characteristics of each layer of the multi-layer material, the present invention particularly designs a high-quality, efficient, and flexible manufacturing method. For example, first, after preparing the electric field shielding layer, taking advantage of the curing characteristics of the magnetic field shielding layer prepreg and the epoxy heat conduction layer, the three layers are laminated and hot-pressed for co-curing, which is beneficial to improving the interlayer bonding force and the overall performance of the product. Second, when setting the heat conduction composite layer, the magnetic field shielding layer prepreg and the heat conduction composite layer prepreg can also be integrally formed by hot pressing to blur the interlayer interface and further improve the heat conduction efficiency and uniformity. In addition, in order to improve the dispersion and matrix compatibility of the magnetic shielding filler in the magnetic field shielding layer and boron nitride in the heat conduction composite layer, the present invention particularly adopts a method of mixing or joining in batches and groups, as well as a surface treatment method, which overall improves the performance stability and uniformity of the product. Description of the Drawings

[0060] Figure 1 The structure diagram of the electromagnetic shielding and heat conduction multi-layer material of the present invention is shown.

[0061] Description of the reference numerals: 1. Polyimide base film; 2. Heat-resistant adhesive layer; 3. Copper foil layer; 4. Heat conduction layer; 5. Magnetic field shielding layer; 6. Heat conduction composite layer; 100. Electric field shielding layer. Detailed Embodiments

[0062] In order to make the purpose, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the drawings and embodiments.

[0063] An electromagnetic shielding and heat conduction multi-layer material sequentially includes the following layers:

[0064] (1) Optional polyimide-based film 1, preferably with a thickness of 20 - 30 μm, a polyimide film formed by biaxially stretching and thermal molding of pyromellitic type;

[0065] (2) Optional heat-resistant adhesive layer 2, with a thickness of 5 - 25 μm for the heat-resistant adhesive layer 2, preferably applied by spraying process; calculated by weight parts, its raw materials include the following components:

[0066]

[0067] Preferably, the epoxy resin is compounded by epoxy resin AG80 and epoxy resin 2133 in a mass ratio of (70 - 80):(20 - 30); the magnesium hydroxide flame retardant is compounded by magnesium hydroxide flame retardant YX105 and magnesium hydroxide flame retardant YX115 in a mass ratio of (8 - 9):(13 - 15), and the solvent is preferably methyl ethyl ketone.

[0068] (3) Copper foil layer 3, with a thickness of 5 - 12 μm, preferably 8 - 10 μm, particularly preferably 9 μm; the copper foil is an electrolytic copper foil, more preferably patterned by an etching process; the said patterning design forms multiple bumps on the surface of the copper foil layer 3, preferably with a bump diameter of 5 - 50 μm and a bump spacing of 50 - 100 μm; the bump density is 100 - 500 pieces / mm 2 . The copper foil layer 3, together with the optional polyimide-based film 1 and the heat-resistant adhesive layer 2, constitutes the electric field shielding layer 100;

[0069] (4) Heat-conducting layer 4, with a thickness of 0.2 - 0.4 μm; joining the copper foil layer 3 and the magnetic field shielding layer 5; the heat-conducting layer 4 is an epoxy resin heat-conducting layer 4, including component A containing epoxy resin and component B containing epoxy curing agent, and when in use, by mixing component A and component B evenly, applying, and curing;

[0070] Preferably, the epoxy resin in component A is compounded by epoxy resin 3102 and epoxy resin 2133 in a mass ratio of (50 - 55):(45 - 50); the epoxy curing agent in component B is epoxy curing agent CYDHD - 593, and component B also includes a magnesium hydroxide flame retardant, compounded by magnesium hydroxide flame retardant YX105 and magnesium hydroxide flame retardant YX115 in a mass ratio of (5 - 7):(8 - 10);

[0071] (5) Magnetic field shielding layer 5, with a thickness of 1.0 - 3.0 mm, preferably 1.8 - 2.5 mm, particularly preferably 2.0 - 2.2 mm; the magnetic field shielding layer 5 includes a resin matrix A doped with magnetic field shielding fillers and carbon fiber cloth distributed therein; calculated by weight parts, the resin matrix A includes the following components:

[0072]

[0073] The magnetic field shielding filler is compounded by nano manganese zinc ferrite and micron nickel powder in a mass ratio of (80 - 120):(30 - 40); the grammage parameter of the carbon fiber cloth is 70 - 100 g / m 2 . Preferably, the nano manganese zinc ferrite and the micron nickel powder are subjected to plasma surface activation treatment, and the specific treatment method is as follows:

[0074] Control the vacuum degree to be 1×10 -2 -10×10 -2 Pa, heat up to 80 - 120 °C, introduce argon gas, and perform surface activation treatment on the surface of the nano manganese zinc ferrite and / or the micron nickel powder by using argon plasma under vacuum, and the treatment time is 1 - 5 min.

[0075] (6) Preferably, the heat-conducting composite layer 6 has a thickness of 1.0 - 2.0 mm, preferably 1.5 - 2.0 mm, and particularly preferably 1.6 - 1.8 mm; it includes a resin matrix B, boron nitride with a particle size of 0.5 - 1.5 μm, and an alkali-free glass fiber cloth with a grammage of 100 - 120 g / m 2 . The ratio of the mass of boron nitride to the total mass of the resin matrix B is (15 - 20):100.

[0076] By weight, the resin matrix B includes the following components:

[0077]

[0078] The preparation method of the heat-conducting composite layer 6 includes the following steps:

[0079] S1: Prepare an ethanol aqueous solution of a silane coupling agent with a mass fraction of 1 - 3%, in which ethanol and pure water are mixed according to a mass ratio of 1:(7 - 10), and then add acetic acid to adjust the pH value to 3 - 4.5, and hydrolyze it at 45 - 75 °C for later use;

[0080] S2: Add boron nitride particles with a particle size of 0.5 - 1.5 μm to the pre-hydrolyzed silane coupling agent solution, mix and react for 2 - 4 h, perform vacuum filtration, wash the obtained solid repeatedly with absolute ethanol, and dry it at 50 - 65 °C and cool it to obtain surface-treated boron nitride particles;

[0081] S3: Add 30 - 70% of the surface-treated boron nitride particles to the resin matrix B, mix evenly to obtain a heat-conducting adhesive; among them, the resin matrix B is prepared by the following steps:

[0082] Step one: Blend bismaleimide resin, 3,3-diallylbisphenol A, and triallyl isocyanurate, react at 95 - 105 °C for 10 - 20 min, and then heat up to 120 - 130 °C and react for 15 - 30 min;

[0083] Step 2: Add vinyltoluene, cardanol, diisopropylbenzene peroxide, and cobalt naphthenate, mix evenly, and discharge after cooling to room temperature.

[0084] S4: Disperse 30 - 70% of the remaining surface-treated boron nitride particles in a methyl ethyl ketone solution with a solid content of 30 - 35 wt%. Vacuum filter and dry to attach the boron nitride particles to the fiberglass cloth.

[0085] S5: Coat the heat-conducting adhesive solution obtained in step S3 on the fiberglass cloth of step S4, and pre-cure to obtain a heat-conducting composite layer 6 prepreg.

[0086] S6: Cure the heat-conducting composite layer 6 prepreg to obtain the heat-conducting composite layer 6.

[0087] The present invention provides the following Preparation Examples 1 - 4 according to the specific composition of the electromagnetic shielding and heat-conducting multi-layer material:

[0088] Preparation Example 1:

[0089] When the electromagnetic shielding and heat-conducting multi-layer material of the present invention includes the above layers (1) - (5), its preparation method includes the following steps:

[0090] S1: Prepare the electric field shielding layer 100: Combine the polyimide-based film 1 and the copper foil layer 3 by spraying a heat-resistant adhesive layer 2 between layers to form the electric field shielding layer 100.

[0091] S2: Prepare the magnetic field shielding layer 5

[0092] S2.1: Prepare the magnetic field shielding adhesive solution: Mix the components of the resin matrix A evenly in proportion, and add the magnetic field shielding filler in batches at (40 - 60%):(20 - 30%):(20 - 30%) of its total mass.

[0093] S2.2: Immerse the carbon fiber cloth in the magnetic field shielding adhesive solution tank for dipping, apply glue with double rollers in reverse, and dry to obtain a magnetic field shielding layer 5 prepreg; specifically including: 1) Immerse the carbon fiber cloth in the glue tank for 5 - 10 seconds, and the pressure for applying glue with double rollers in reverse is 0.3 - 0.8 MPa; 2) Stepwise drying: Bake at 95 - 105 °C for 10 seconds, 140 - 160 °C for 10 seconds, and 120 - 140 °C for 10 seconds.

[0094] S2.3: Thermally press the magnetic field shielding layer 5 prepreg to form the magnetic field shielding layer 5. The above thermocompression molding conditions may include:

[0095] 1) Preheat at 130 - 150 °C for 25 - 30 minutes, apply pressure of 3 ± 0.5 MPa, after 8 - 15 minutes, raise the temperature to 160 - 180 °C, raise the pressure to 5 ± 0.5 MPa, and maintain for 2.5 - 3.5 hours.

[0096] 2) Heat up to 195 - 205 °C, increase the pressure to 10 ± 0.5 MPa, and maintain for 1.5 - 2.5 h;

[0097] S3: Prepare epoxy thermal conductive adhesive: The epoxy thermal conductive adhesive includes component A containing epoxy resin and component B containing epoxy curing agent;

[0098] S4: Mix component A and component B of the epoxy thermal conductive adhesive prepared in S3 evenly, apply it on the surface of copper foil layer 3 within 10 - 20 min, stack the surface of copper foil layer 3 with the epoxy thermal conductive adhesive on the magnetic field shielding layer 5, and heat and cure the epoxy thermal conductive adhesive to form an electromagnetic shielding thermal conductive multi-layer material.

[0099] Preparation Example 2:

[0100] When the electromagnetic shielding thermal conductive multi-layer material of the present invention includes the above layers (1)-(5), the thermal conductive layer 4 containing epoxy thermal conductive adhesive and the magnetic field shielding layer 5 are thermocompression co-cured and bonded. Its preparation method includes the following steps:

[0101] S1: Prepare the electric field shielding layer 100: Combine the polyimide base film 1 and the copper foil layer 3 by spraying a heat-resistant adhesive layer 2 between layers to form the electric field shielding layer 100;

[0102] S2: Prepare the prepreg of the magnetic field shielding layer 5

[0103] S2.1: Prepare the magnetic field shielding adhesive solution: Mix the components of resin matrix A evenly in proportion, and add the magnetic field shielding filler in batches at (40 - 60%) : (20 - 30%) : (20 - 30%) of its total mass;

[0104] S2.2: Immerse the carbon fiber cloth in the magnetic field shielding adhesive solution tank for impregnation, apply glue with double rollers in reverse, and dry to obtain the prepreg of the magnetic field shielding layer 5; specifically including: 1) Immerse the carbon fiber cloth in the glue tank for 5 - 10 sec, and the pressure for applying glue with double rollers in reverse is 0.3 - 0.8 MPa; 2) Step-by-step drying: Bake at 95 - 105 °C for 10 sec, 140 - 160 °C for 10 sec, and 120 - 140 °C for 10 sec;

[0105] S3: Prepare epoxy thermal conductive adhesive: The epoxy thermal conductive adhesive includes component A containing epoxy resin and component B containing epoxy curing agent;

[0106] S4: Mix component A and component B of the epoxy thermal conductive adhesive prepared in S3 evenly, apply it on the surface of copper foil layer 3 within 10 - 20 min, stack the surface of copper foil layer 3 with the epoxy thermal conductive adhesive on the prepreg of the magnetic field shielding layer 5, and thermocompression co-cure to obtain the electromagnetic shielding thermal conductive multi-layer material. The above thermocompression molding conditions may include:

[0107] 1) Preheat at 130 - 150 °C for 25 - 30 min, apply a pressure of 3 ± 0.5 MPa. After 8 - 15 min, raise the temperature to 160 - 180 °C and increase the pressure to 5 ± 0.5 MPa, and maintain for 2.5 - 3.5 h;

[0108] 2) Raise the temperature to 195 - 205 °C, increase the pressure to 10 ± 0.5 MPa, and maintain for 1.5 - 2.5 h.

[0109] Preparation Example 3:

[0110] When the electromagnetic shielding and heat - conducting multi - layer material includes the above layers (1) - (6), that is, when there is also a heat - conducting composite layer 6 outside the magnetic - field shielding layer 5, first integrally hot - press form the magnetic - field shielding layer 5 prepreg and the heat - conducting composite layer 6 prepreg, and then combine the electric - field shielding layer 100 and the magnetic - field shielding layer 5 through the epoxy heat - conducting adhesive of the heat - conducting layer 4. Its preparation method may include the following steps:

[0111] S1: Prepare the electric - field shielding layer 100: Combine the polyimide - based film 1 and the copper foil layer 3 by spraying a heat - resistant adhesive layer 2 between layers to form the electric - field shielding layer 100;

[0112] S2: Prepare the magnetic - field shielding layer 5 prepreg

[0113] S2.1: Prepare the magnetic - field shielding adhesive solution: Mix the components of the resin matrix A evenly in proportion, and add the magnetic - field shielding fillers in batches at (40 - 60%):(20 - 30%):(20 - 30%) of its total mass;

[0114] S2.2: Immerse the carbon fiber cloth in the magnetic - field shielding adhesive solution tank for dipping, apply double - roll reverse coating, and obtain the magnetic - field shielding layer 5 prepreg after drying; specifically including: 1) Immerse the carbon fiber cloth in the adhesive solution tank for 5 - 10 sec, and the double - roll reverse coating pressure is 0.3 - 0.8 MPa; 2) Step - by - step drying: Dry at 95 - 105 °C for 10 sec, 140 - 160 °C for 10 sec, and 120 - 140 °C for 10 sec;

[0115] S3: Prepare the heat - conducting composite layer 6 prepreg

[0116] S3.1: Prepare an ethanol aqueous solution of silane coupling agent with a mass fraction of 1 - 3%, where ethanol and pure water are mixed in a mass ratio of 1:(7 - 10), then add acetic acid to adjust the pH value to 3 - 4.5, and hydrolyze at 45 - 75 °C for standby;

[0117] S3.2: Add boron nitride particles with a particle size of 0.5 - 1.5 μm to the pre - hydrolyzed silane coupling agent solution, mix and react for 2 - 4 h, vacuum filter, wash the obtained solid repeatedly with anhydrous ethanol, and dry at 50 - 65 °C and cool to obtain surface - treated boron nitride particles;

[0118] S3.3: Add 30 - 70% of the total amount of boron nitride particles to the resin matrix B and mix evenly to obtain a thermally conductive adhesive solution;

[0119] S3.4: Disperse 30 - 70% of the total amount of boron nitride particles in a methyl ethyl ketone solution with a solid content of 30 - 35 wt%; perform vacuum filtration and drying to attach the boron nitride particles to the fiberglass cloth;

[0120] S3.5: Coat the thermally conductive adhesive solution obtained in step S3.3 onto the fiberglass cloth of step S3.4 and pre-cure to obtain a thermally conductive composite layer 6 prepreg;

[0121] S3.6: Stack the magnetic field shielding layer 5 prepreg and the thermally conductive composite layer 6 prepreg and hot-press them into an integral structure. The above hot-pressing conditions may include:

[0122] 1) Preheat at 130 - 150 °C for 25 - 30 min, apply a pressure of 3 ± 0.5 MPa, after 8 - 15 min, raise the temperature to 160 - 180 °C, raise the pressure to 5 ± 0.5 MPa, and hold for 2.5 - 3.5 h;

[0123] 2) Raise the temperature to 195 - 205 °C, raise the pressure to 10 ± 0.5 MPa, and hold for 1.5 - 2.5 h.

[0124] S4: Prepare an epoxy thermally conductive adhesive: The epoxy thermally conductive adhesive includes component A containing epoxy resin and component B containing an epoxy curing agent;

[0125] S5: Mix component A and component B of the epoxy thermally conductive adhesive prepared in S4 evenly, apply it to the surface of the copper foil layer 3 within 10 - 20 min, stack the side of the copper foil layer 3 with the epoxy thermally conductive adhesive on the magnetic field shielding layer 5, and heat-cure the epoxy thermally conductive adhesive to form an electromagnetic shielding and thermally conductive multi-layer material.

[0126] Preparation Example 4:

[0127] When the electromagnetic shielding and thermally conductive multi-layer material includes the above layers (1) - (6), that is, when there is also a thermally conductive composite layer 6 outside the magnetic field shielding layer 5, hot-press the epoxy thermally conductive adhesive of the (4) thermally conductive layer 4, the (5) magnetic field shielding layer 5 prepreg, and the (6) thermally conductive composite layer 6 prepreg as a whole. Its preparation method may include the following steps:

[0128] S1: Prepare an electric field shielding layer 100: Combine the polyimide-based film 1 and the copper foil layer 3 by spraying a heat-resistant adhesive layer 2 between layers to form an electric field shielding layer 100;

[0129] S2: Prepare the magnetic field shielding layer 5 prepreg

[0130] S2.1: Prepare the magnetic field shielding adhesive solution: Mix the components of resin matrix A evenly according to the proportion. Among them, the magnetic field shielding filler is added in batches in the ratio of (40 - 60%):(20 - 30%):(20 - 30%) of its total mass;

[0131] S2.2: Immerse the carbon fiber cloth in the magnetic field shielding adhesive solution tank for dipping, apply the adhesive with double rollers in reverse, and obtain the prepreg of the magnetic field shielding layer 5 after drying. Specifically, it includes: 1) Immerse the carbon fiber cloth in the adhesive solution in the tank for 5 - 10 seconds, and the pressure for applying the adhesive with double rollers in reverse is 0.3 - 0.8 MPa; 2) Step - by - step drying: Dry at 95 - 105°C for 10 seconds, 140 - 160°C for 10 seconds, and 120 - 140°C for 10 seconds;

[0132] S3: Prepare the prepreg of the thermal - conductive composite layer 6

[0133] S3.1: Configure an ethanol aqueous solution of silane coupling agent with a mass fraction of 1 - 3%. Among them, ethanol and pure water are mixed according to a mass ratio of 1:(7 - 10), and then acetic acid is added to adjust the pH value to 3 - 4.5, and hydrolyze it at 45 - 75°C for standby;

[0134] S3.2: Add boron nitride particles with a particle size of 0.5 - 1.5 μm to the pre - hydrolyzed silane coupling agent solution, mix and react for 2 - 4 h, vacuum filter, wash the obtained solid repeatedly with absolute ethanol, and dry it at 50 - 65°C, and cool to obtain surface - treated boron nitride particles;

[0135] S3.3: Add 30 - 70% of the total amount of boron nitride particles to resin matrix B, mix evenly to obtain the thermal - conductive adhesive solution;

[0136] S3.4: Disperse 30 - 70% of the total amount of boron nitride particles in the butanone solution, with a solid content of 30 - 35 wt%; Vacuum filter and dry to make the boron nitride particles adhere to the glass fiber cloth;

[0137] S3.5: Coat the thermal - conductive adhesive solution obtained in step S3.3 on the glass fiber cloth in step S3.4, and pre - cure to obtain the prepreg of the thermal - conductive composite layer 6;

[0138] S4: Prepare the epoxy thermal - conductive adhesive: The epoxy thermal - conductive adhesive includes component A containing epoxy resin and component B containing epoxy curing agent;

[0139] S5: Mix component A and component B of the epoxy thermal - conductive adhesive prepared in S4 evenly, apply it on the surface of the copper foil layer 3 within 10 - 20 minutes, and stack the side of the copper foil layer 3 with the epoxy thermal - conductive adhesive on the magnetic field shielding layer 5 prepreg and the thermal - conductive composite layer 6 prepreg in turn, and integrally hot - press to form the electromagnetic shielding and thermal - conductive multi - layer material.

[0140] The above hot - pressing forming conditions may include:

[0141] 1) Preheat at 130 - 150 °C for 25 - 30 min, apply a pressure of 3 ± 0.5 MPa. After 8 - 15 min, raise the temperature to 160 - 180 °C and the pressure to 5 ± 0.5 MPa, and maintain for 2.5 - 3.5 h;

[0142] 2) Raise the temperature to 195 - 205 °C and the pressure to 10 ± 0.5 MPa, and maintain for 1.5 - 2.5 h.

[0143] The shape of the hot - pressing mold can be selected according to the application scenario. When used for encapsulating components, the corresponding encapsulation space can be pressed out.

[0144] Based on the above Preparation Examples 1 - 4, the present invention provides the following Examples and Comparative Examples:

[0145] Example 1

[0146] The electromagnetic - shielding and heat - conducting multi - layer material of this example successively includes the following layers:

[0147] (1) Polyimide base film 1, with a thickness of 25 μm, a polyimide film formed by biaxial stretching thermal method of pyromellitic type;

[0148] (2) Heat - resistant adhesive layer 2, with a thickness of 10 μm. Apply glue on the polyimide base film 1 by spraying process, and an electrolytic copper foil layer 3 adheres after the solvent volatilizes. By weight, its raw materials include the following components:

[0149]

[0150] (3) Copper foil layer 3, with a thickness of 9 μm; Form a plurality of bumps on the surface of the copper foil layer 3 through an etching process. The diameter of the bumps is 30 ± 5 μm, and the bump pitch is 90 ± 10 μm (the distance between the centers of two bumps); The polyimide base film 1, the copper foil layer 3, and the heat - resistant adhesive layer 2 together form an electric - field shielding layer 100.

[0151] (4) Heat - conducting layer 4, with a thickness of 0.3 μm; Bond the copper foil layer 3 with the magnetic - field shielding layer 5; The heat - conducting layer 4 is an epoxy resin heat - conducting layer 4, which includes component A containing epoxy resin 3102 and epoxy resin 2133 compounded at a mass ratio of 50:50 and component B containing an epoxy curing agent. When in use, mix component A and component B evenly, apply, and cure;

[0152] (5) Magnetic - field shielding layer 5, with a thickness of 2.0 mm; The magnetic - field shielding layer 5 includes a resin matrix A doped with magnetic - field shielding fillers and carbon fiber cloth; By weight, the resin matrix A includes the following components:

[0153]

[0154] The magnetic field shielding filler is a magnetic field shielding filler prepared by compounding nano manganese-zinc ferrite and micron nickel powder in a mass ratio of 3:2; the gram weight parameter of the carbon fiber cloth is 80 g / m 2 .

[0155] This example is prepared by the method of Preparation Example 1 to obtain Sample S1, which specifically includes the following steps:

[0156] S1: Prepare the electric field shielding layer 100: Combine the polyimide base film 1 and the copper foil layer 3 by spraying a heat-resistant adhesive layer 2 between layers to form the electric field shielding layer 100;

[0157] S2: Prepare the magnetic field shielding layer 5

[0158] S2.1: Prepare the magnetic field shielding adhesive solution: Mix the components of the resin matrix A evenly in proportion, wherein the magnetic field shielding filler is added in batches at 40%:30%:30% of its total mass; and the micron nickel powder is added first, and then the nano manganese-zinc ferrite is added in batches;

[0159] S2.2: Immerse the carbon fiber cloth in the magnetic field shielding adhesive solution tank for dipping, and apply the adhesive with double rollers in the reverse direction, and dry it to obtain the prepreg of the magnetic field shielding layer 5; specifically including: 1) Immerse the carbon fiber cloth in the adhesive solution in the tank for 5 seconds, and the pressure for applying the adhesive with double rollers in the reverse direction is 0.5 MPa; 2) Step drying: Dry at 100 °C for 10 seconds, 150 °C for 10 seconds, and 130 °C for 10 seconds;

[0160] S2.3: Thermally press the prepreg of the magnetic field shielding layer 5 to obtain the magnetic field shielding layer 5. The above thermocompression molding conditions may include:

[0161] 3) Preheat at 140 °C for 30 minutes, apply a pressure of 3 ± 0.5 MPa, after 10 minutes, raise the temperature to 170 °C, and raise the pressure to 5 ± 0.5 MPa, and hold for 3 hours;

[0162] 4) Raise the temperature to 200 °C, raise the pressure to 10 ± 0.5 MPa, and hold for 2 hours;

[0163] S3: Prepare the epoxy thermal conductive adhesive: The epoxy thermal conductive adhesive includes component A containing epoxy resin and component B containing epoxy curing agent;

[0164] S4: Mix the component A and component B of the epoxy thermal conductive adhesive prepared in S3 evenly, apply it on the surface of the copper foil layer 3 within 20 minutes, stack the surface of the copper foil layer 3 with the epoxy thermal conductive adhesive on the magnetic field shielding layer 5, and heat and cure the epoxy thermal conductive adhesive to form an electromagnetic shielding and thermal conductive multi-layer material.

[0165] Example 2

[0166] The material composition and layered structure of this example are the same as those of Example 1, and the sample S2 is prepared by the method of Preparation Example 1. The main difference is that a copper foil with a thickness of 9 μm but not etched is used.

[0167] Example 3

[0168] The material composition and layered structure of this example are the same as those of Example 1, but it is prepared by the method of Preparation Example 2 to obtain the sample S3. Among them, the heat-conducting layer 4 containing epoxy heat-conducting adhesive and the magnetic field shielding layer 5 are thermally pressed and co-cured.

[0169] Its preparation method includes the following steps:

[0170] S1: Prepare the electric field shielding layer 100: By spraying a heat-resistant adhesive layer 2 between layers, the polyimide base film 1 and the copper foil layer 3 are combined to form the electric field shielding layer 100;

[0171] S2: Prepare the prepreg of the magnetic field shielding layer 5

[0172] S2.1: Prepare the magnetic field shielding adhesive solution: Mix the components of the resin matrix A evenly according to the ratio. Among them, the magnetic field shielding filler is added in batches at 40%:30%:30% of its total mass; and the micron nickel powder is added first, and then the nano manganese-zinc ferrite is added in batches;

[0173] S2.2: Immerse the carbon fiber cloth in the magnetic field shielding adhesive solution tank for impregnation, and apply the adhesive with double rollers in the reverse direction. After drying, the prepreg of the magnetic field shielding layer 5 is obtained; specifically including: 1) Immerse the carbon fiber cloth in the adhesive solution in the tank for 5 seconds, and the pressure for applying the adhesive with double rollers in the reverse direction is 0.5 MPa; 2) Stepwise drying: Bake at 100 °C for 10 seconds, 150 °C for 10 seconds, and 130 °C for 10 seconds;

[0174] S3: Prepare the epoxy heat-conducting adhesive: The epoxy heat-conducting adhesive includes component A containing epoxy resin and component B containing epoxy curing agent;

[0175] S4: Mix the component A and component B of the epoxy heat-conducting adhesive prepared in S3 evenly, apply it on the surface of the copper foil layer 3 within 20 minutes, and laminate the surface of the copper foil layer 3 with the epoxy heat-conducting adhesive with the prepreg of the magnetic field shielding layer 5, and thermally press and co-cure to obtain the electromagnetic shielding and heat-conducting multi-layer material. The above thermoforming conditions may include:

[0176] 1) Preheat at 140 °C for 30 minutes, apply pressure of 3 ± 0.5 MPa. After 10 minutes, raise the temperature to 170 °C, and raise the pressure to 5 ± 0.5 MPa, and keep it for 3 hours;

[0177] 2) Raise the temperature to 200 °C, raise the pressure to 10 ± 0.5 MPa, and keep it for 2 hours;

[0178] Example 4

[0179] The electromagnetic shielding heat-conducting multilayer material of this embodiment includes the following layers in sequence:

[0180] (1) a polyimide base film 1, having a thickness of 25 μm, and being a polyimide film formed by a biaxial stretching heat method;

[0181] (2) A heat-resistant adhesive layer 2 having a thickness of 10 μm is applied on the polyimide base film 1 by a spraying process, and an electrolytic copper foil layer 3 is attached after the solvent evaporates; the raw materials thereof include the following components by weight:

[0182]

[0183]

[0184] (3) a copper foil layer 3 having a thickness of 9 μm; a plurality of bumps are formed on the surface of the copper foil layer 3 by an etching process, wherein the diameter of the bumps is 30±5 μm and the distance between the bumps is 90±10 μm (the distance between the centers of two bumps); the polyimide base film 1, the copper foil layer 3 and the heat-resistant adhesive layer 2 together constitute an electric field shielding layer 100.

[0185] (4) a heat-conducting layer 4 having a thickness of 0.3 μm; the copper foil layer 3 is bonded to the magnetic field shielding layer 5; the heat-conducting layer 4 is an epoxy resin heat-conducting layer 4, comprising a component A containing epoxy resin 3102 and epoxy resin 2133 in a mass ratio of 50:50 and a component B containing an epoxy curing agent, wherein the components A and B are mixed evenly, applied, and cured during use;

[0186] (5) A magnetic field shielding layer 5 having a thickness of 2.0 mm; the magnetic field shielding layer 5 comprises a resin matrix A doped with a magnetic field shielding filler and a carbon fiber cloth; the resin matrix A comprises the following components in parts by weight:

[0187]

[0188] The magnetic field shielding filler is a composite magnetic field shielding filler of nano manganese zinc ferrite and micron nickel powder in a mass ratio of 3:2; the gram weight parameter of the carbon fiber cloth is 80g / m 2 .

[0189] (6) Thermally conductive composite layer 6, with a thickness of 1.6 mm; comprising a resin matrix B, boron nitride with a particle size of 0.5-1.5 μm, and a gram weight of 110 g / m 2 Alkali-free glass fiber cloth; the ratio of the mass of boron nitride to the total mass of the resin matrix B is 18:100.

[0190] The resin matrix B comprises the following components in parts by weight:

[0191]

[0192] The preparation method of the heat-conducting composite layer 6 comprises the following steps:

[0193] S1: Prepare an ethanol aqueous solution of a silane coupling agent with a mass fraction of 3%, wherein ethanol and pure water are mixed according to a mass ratio of 1:8, and then acetic acid is added to adjust the pH value to 4 ± 0.2, and hydrolyze it at 60 °C for standby;

[0194] S2: Add boron nitride particles with a particle size of 0.5 - 1.5 μm to the pre-hydrolyzed silane coupling agent solution, mix and react for 3 h, perform vacuum filtration, repeatedly wash the obtained solid with absolute ethanol, dry it at 60 °C, and cool it to obtain surface-treated boron nitride particles;

[0195] S3: Add 60% of the total amount of boron nitride particles to the resin matrix B, mix evenly to obtain a heat-conducting adhesive; wherein, the resin matrix B is prepared through the following steps:

[0196] Step 1: Blend bismaleimide resin, 3,3-diallylbisphenol A, and triallyl isocyanurate, react at 100 °C for 15 min, and raise the temperature to 125 °C and react for 20 min;

[0197] Step 2: Add vinyltoluene, cashew phenol, diisopropylbenzene peroxide, and cobalt naphthenate, mix evenly, and discharge at room temperature;

[0198] S4: Disperse 40% of the total amount of boron nitride particles in a butanone solution with a solid content of 30 wt%; perform vacuum filtration and drying to make the boron nitride particles adhere to the fiberglass cloth;

[0199] S5: Coat the heat-conducting adhesive obtained in step S3 on the fiberglass cloth in step S4, and pre-cure it to obtain a pre-preg of the heat-conducting composite layer 6;

[0200] S6: Cure the pre-preg of the heat-conducting composite layer 6 to obtain the heat-conducting composite layer 6.

[0201] In this embodiment, the method of Preparation Example 3 is adopted for preparation to obtain Sample S4. Among them, for the pre-preg of the magnetic field shielding layer 5, and the hot pressing conditions for hot pressing the pre-preg of the magnetic field shielding layer 5 and the pre-preg of the heat-conducting composite layer 6 into an integrated structure, and the specific conditions for preparing and applying the epoxy heat-conducting adhesive, etc., reference can be made to Embodiments 1 - 3.

[0202] Example 5

[0203] The material composition and layered structure of this embodiment are the same as those of Example 4, but it is prepared by the method of Preparation Example 4 to obtain sample S5. Among them, (4) the heat-conducting layer 4, (5) the magnetic field shielding layer 5, and (6) the heat-conducting composite layer 6 are integrally formed by hot pressing and co-curing. For the prepreg of the magnetic field shielding layer 5 and the hot pressing conditions for integrally forming the heat-conducting layer 4, the prepreg of the magnetic field shielding layer 5, and the prepreg of the heat-conducting composite layer 6 into a single structure, reference can be made to Examples 1-4.

[0204] Example 6

[0205] The material composition, layered structure, and preparation method of this embodiment are the same as those of Example 5 to obtain sample S6, except that: the nano-manganese zinc ferrite and micron nickel powder of the magnetic field shielding filler are subjected to plasma surface activation treatment. The specific method is: control the vacuum degree to 2×10 -2 Pa, heat up to 90 °C, introduce argon gas, and use argon plasma under vacuum to perform surface activation treatment on the surface of nano-manganese zinc ferrite and micron nickel powder respectively, and the treatment time is 3 min.

[0206] Comparative Example 1

[0207] This comparative example has a similar material composition, layer structure, and preparation method to Example 1 (Example 1 does not contain a heat-conducting composite layer). The main difference is that: the heat-conducting layer is not used, that is, the copper foil layer and the prepreg of the magnetic field shielding layer are laminated and combined by hot pressing to obtain an electromagnetic shielding and heat-conducting multi-layer material.

[0208] The above hot pressing conditions may include:

[0209] 1) Preheat at 140 °C for 25 min, apply a pressure of 3 ± 0.5 MPa. After 10 min, heat up to 170 °C and increase the pressure to 5 ± 0.5 MPa, and hold for 3 h;

[0210] 2) Heat up to 200 °C, increase the pressure to 10 ± 0.5 MPa, and hold for 2 h.

[0211] Comparative Example 2

[0212] This comparative example has the same layer structure and preparation method as Example 5. The main difference is that: the magnetic field shielding layer does not contain magnetic field shielding filler.

[0213] Comparative Example 3

[0214] This comparative example has the same layer structure and preparation method as Example 5. The main difference is that: the magnetic field shielding layer does not contain carbon fiber cloth.

[0215] Performance test and results:

[0216] The performance of Examples 1-6 and Comparative Examples 1-3 was tested, and the results are shown in Table 1.

[0217] Electromagnetic shielding effectiveness and durability: The electromagnetic shielding effectiveness and durability of the samples of Examples 1-6 and Comparative Examples 1-3 were tested. Among them, the test frequency range of the electromagnetic shielding effectiveness was 0.1 MHz - 40 GHz, and the test method was a method well-known in the art. In particular, it is pointed out that the test result of the electromagnetic shielding effectiveness H1 listed in the present invention is the lowest value of the electromagnetic shielding effectiveness of the sample within the test frequency range to reflect the overall electromagnetic shielding performance of the sample; after the above samples were heat-treated at 200 °C for 240 hours, the electromagnetic shielding effectiveness H2 was tested according to the same method, and the durability was calculated as H1 / H2×100%.

[0218] Thermal conductivity: The thermal conductivity of the samples was tested according to ASTM D5470.

[0219] Mechanical properties: The tensile strength was tested according to the standard GB / T 1040-2018.

[0220] The above Examples 1-6 were compared with Comparative Examples 1-3, and the specific test results are shown in Table 1:

[0221] Table 1 Performance test results of Examples 1-6 and Comparative Examples 1-3

[0222]

[0223] From the test results, it can be seen that the electromagnetic shielding effectiveness of the Examples is better than that of the Comparative Examples, especially the electromagnetic shielding effectiveness after heat treatment. The durability of the Examples is above 90%, while the durability of the Comparative Examples is relatively low, and the shielding performance of the materials decreases significantly, making it difficult to meet the long-term use requirements in high-temperature and high-electromagnetic field environments.

[0224] In terms of thermal conductivity, Examples 4-6 with a thermal conductive composite layer have a higher thermal conductivity. And through the co-curing of Examples 5 and 6, their interlayer bonding performance is better and the heat conduction is more uniform and smooth. Among them, Example 6 with surface treatment of the magnetic shielding filler has a more excellent thermal conductivity. The main reason is that the magnetic shielding filler also has certain thermal conductivity, and the filler after surface treatment has better dispersion and compatibility in the matrix, which is beneficial to improving the overall thermal conductivity of the material. Comparative Example 1 has no thermal conductive layer or thermal conductive composite layer, and mainly relies on the copper foil layer and magnetic field shielding layer therein for heat conduction, and its thermal conductivity and heat conduction uniformity are relatively low.

[0225] In terms of mechanical properties, the thermal conductive composite layer has both heat conduction and strengthening effects, so Examples 4-6 with a thermal conductive composite layer and Comparative Examples 2-3 are relatively good.

[0226] The above describes the preferred embodiments of the present invention, aiming to make the spirit of the present invention clearer and easier to understand, rather than to limit the present invention. Any modifications, substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection covered by the claims appended to the present invention.

Claims

1. An electromagnetic shielding and heat-conducting multi-layer material, characterized in that, The multi-layer material sequentially includes an electric field shielding layer, an epoxy thermal conductive adhesive layer, and a magnetic field shielding layer; The electric field shielding layer includes a copper foil layer and a polyimide base film. The thickness of the copper foil layer is 5 - 12 μm, and there are multiple bumps on the surface of the copper foil layer; the polyimide base film and the copper foil layer are joined through a heat-resistant adhesive layer; The thickness of the magnetic field shielding layer is 1 - 3 mm, and it includes a resin matrix A and carbon fiber cloth distributed therein; by weight, the resin matrix A includes the following components: The magnetic field shielding filler is compounded by nano-manganese zinc ferrite and micron nickel powder with a mass ratio of (80 - 120):(30 - 40); The multi-layer material further includes a thermal conductive composite layer with a thickness of 1.0 - 2.0 mm. The thermal conductive composite layer is located on the surface of the magnetic field shielding layer opposite to the electric field shielding layer, and includes a resin matrix B, micron-sized boron nitride, and glass fiber cloth; the mass ratio of the micron-sized boron nitride to the resin matrix B is (15 - 20):100; by weight, the resin matrix B includes the following components:

2. The multi-layer material according to claim 1, wherein The thickness of the electric field shielding layer is 20 - 100 μm.

3. The multi-layer material according to claim 2, wherein The thickness of the heat-resistant adhesive layer is 5 - 25 μm. By weight, its raw materials include the following components:

4. The multi-layer material according to any one of claims 1-3, characterized in that, The diameter of the bump is 5 - 50 μm.

5. The multilayer material according to claim 4, characterized in that, The spacing between the bumps is 50 - 100 μm.

6. The multi-layer material according to claim 5, wherein The density of the bumps is 100 - 500 bumps / mm 2 .

7. The multi-layer material according to any one of claims 1-3, characterized in that, The preparation method of the thermal conductive composite layer includes the following steps: S1: Prepare an ethanol aqueous solution of silane coupling agent with a mass fraction of 1 - 3%, wherein ethanol and pure water are mixed according to a mass ratio of 1:(7 - 10), and then acetic acid is added to adjust the pH value to 3 - 4.5, and it is pre-hydrolyzed at 45 - 75 °C for standby; S2: Add boron nitride particles with a particle size of 0.5 - 1.5 μm to the pre-hydrolyzed silane coupling agent solution, mix and react for 2 - 4 h, vacuum filter, and the obtained solid is repeatedly washed with anhydrous ethanol and dried at 50 - 65 °C and cooled to obtain surface-treated boron nitride particles; S3: Add 30 - 70% of the surface-treated boron nitride particles to the resin matrix B and mix evenly to obtain a thermal conductive adhesive solution; S4: Disperse the remaining 30 - 70% of the surface-treated boron nitride particles in a butanone solution with a solid content of 30 - 35 wt%; vacuum filter and dry to make the boron nitride particles adhere to the glass fiber cloth; S5: Coating the thermal conductive adhesive solution obtained in step S3 on the glass fiber cloth in step S4, and pre-curing to obtain a pre-preg of the thermal conductive composite layer; S6: Cure the pre-preg of the thermal conductive composite layer to obtain the thermal conductive composite layer.

8. The multi-layer material according to claim 7, wherein, The magnetic field shielding layer and the thermal conductive composite layer are an integral structure and are obtained through the following forming steps: Coat and dry the adhesive solution of the resin matrix A of the magnetic field shielding layer on the carbon fiber cloth to obtain a pre-preg of the magnetic field shielding layer; Stack the pre-preg of the magnetic field shielding layer and the pre-preg of the thermal conductive composite layer and hot-press them into an integral structure.

9. A method for preparing an electromagnetic shielding and heat-conducting multi-layer material according to any one of claims 1-8, characterized in that, Including the following steps: S1: Prepare a pre-preg of the magnetic field shielding layer S1.1: Prepare a magnetic field shielding adhesive solution: Mix the components of the resin matrix A evenly according to the ratio, and among them, the magnetic field shielding filler is added in batches at (40 - 60%):(20 - 30%):(20 - 30%) of its total mass; S1.2: Immerse the carbon fiber cloth into the magnetic field shielding adhesive solution in an adhesive tank, apply the adhesive with double rollers in reverse directions, and obtain the prepreg of the magnetic field shielding layer after drying. S2: Prepare the epoxy thermal conductive adhesive: The epoxy thermal conductive adhesive includes component A containing epoxy resin and component B containing epoxy curing agent. S3: Mix component A and component B of the epoxy thermal conductive adhesive prepared in S2 evenly, apply it on the surface of the copper foil layer within 10 - 20 minutes, laminate the side of the copper foil layer with the epoxy thermal conductive adhesive with the magnetic field shielding layer prepreg, and hot press to form the electromagnetic shielding and thermal conductive multi-layer material.

10. The preparation method according to claim 9, characterized in that, Before step S2, there is also a step of preparing the prepreg of the thermal conductive composite layer. The thermal conductive composite layer includes resin matrix B, micron-sized boron nitride, and glass fiber cloth. And step S3 includes laminating the side of the copper foil layer with the epoxy thermal conductive adhesive with the magnetic field shielding layer prepreg and the thermal conductive composite layer prepreg in sequence, and hot press to form the electromagnetic shielding and thermal conductive multi-layer material.

Images