An interlocked high thermal conductivity and wave-absorbing composite film and its preparation method

Abstract

The present invention relates to an interlocked high thermal conductivity wave-absorbing composite film and a preparation method thereof. When preparing the interlocked high thermal conductivity wave-absorbing composite film, the following steps are included: S1. Select three film substrates according to wave-absorbing and reflection properties; S2. Make two film substrates into wave-absorbing films with through holes of a continuous periodic structure, and make one film substrate into a wave-absorbing film with through holes of a discontinuous periodic structure, and fill the through holes of the periodic structure with a thermal conductive adhesive; S3. Stack and paste the three wave-absorbing films in sequence through the thermal conductive adhesive, so that the thermal conductive adhesives on the three wave-absorbing films are connected to form a three-dimensional thermal conduction path. The advantages of the present invention are as follows: By combining electromagnetic principles and thermal conduction path design, the prepared composite film realizes the integration of thermal conductivity and wave absorption through its structure.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic compatibility materials, and particularly relates to an interlocked high thermal conductivity and wave absorbing composite film and a preparation method thereof. Background Art

[0002] With the advent of the 5G era, electronic products are gradually developing towards miniaturization and high power. The number of transistors per unit area increases year by year, which means that the electronic components encapsulated in the circuit board will generate more heat. At the same time, due to the inevitable electromagnetic radiation, electromagnetic scattering and electromagnetic compatibility problems during the operation of the circuit board and the chip, it is necessary to absorb the electromagnetic waves radiated by them. Therefore, the preparation of materials with both thermal conductivity and wave absorption has important application value.

[0003] Currently, the design of high thermal conductivity and wave absorbing materials mainly focuses on the formulation design of materials, and there is less integrated design of thermal conductivity and wave absorption through the structure. Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art, and provide an interlocked high thermal conductivity and wave absorbing composite film and a preparation method thereof. By combining electromagnetic principles and thermal conduction path design, the prepared composite film realizes the integration of thermal conductivity and wave absorption through the structure.

[0005] The purpose of the present invention is realized through the following technical solutions:

[0006] 1. A preparation method of an interlocked high thermal conductivity and wave absorbing composite film, comprising the following steps:

[0007] S1. Select three film substrates according to wave absorption and reflection performance;

[0008] S2. Make two film substrates into wave absorbing films with through holes of continuous periodic structure, and make one film substrate into a wave absorbing film with through holes of discontinuous periodic structure, and fill the through holes of the periodic structure with thermal conductive glue;

[0009] S3. Stack and paste the three wave absorbing films in sequence through the thermal conductive glue, so that the thermal conductive glue on the three wave absorbing films is connected to form a three-dimensional thermal conduction path.

[0010] Further, in step S1, the film substrate is a magnetic film, and the electromagnetic parameters of the film substrate are that the real part of the dielectric is 100 - 550, the loss angle is 0.1 - 0.5, the real part of the magnetic permeability is 0.1 - 5, and the loss angle is 2 - 8.

[0011] Further, in step S2, when preparing the wave - absorbing thin film with through - holes of continuous periodic structure, a engraving machine is used to engrave through - holes of periodic structure on the surface of the thin - film substrate according to the CAD - designed dimensions of the through - holes of continuous periodic structure. Then, 0.03 - mm thermal conductive adhesive is pasted on the surface of a metal plate coated with silicone oil centrifuging agent, and the engraving machine is used to engrave the thermal conductive adhesive into the same shape as the through - holes of continuous periodic structure. Finally, the redundant thermal conductive adhesive is removed, and the thin - film substrate is combined with the remaining part of the thermal conductive adhesive, so that the thermal conductive adhesive fills the through - holes of continuous periodic structure on the thin - film substrate.

[0012] Further, in step S2, when preparing the wave - absorbing thin film with through - holes of non - continuous periodic structure, first, 0.1 - mm thermal conductive adhesive is pasted on a metal plate and the thin - film substrate is pasted above the thermal conductive adhesive. The engraving machine is used to cut the thin - film substrate according to the CAD - designed dimensions of the through - holes of non - continuous periodic structure. After cutting, the thin - film substrate at the position of the through - holes of non - continuous periodic structure is taken out. Then, 0.03 - mm thermal conductive adhesive is pasted on the surface of a metal plate coated with silicone oil centrifuging agent, and the engraving machine is used to engrave the thermal conductive adhesive into the same shape as the through - holes of non - continuous periodic structure. Finally, the redundant thermal conductive adhesive is removed, and the remaining thin - film substrate is combined with the remaining part of the thermal conductive adhesive, so that the thermal conductive adhesive fills the through - holes of non - continuous periodic structure on the thin - film substrate.

[0013] Further, the CAD - designed dimensions of both the through - holes of continuous periodic structure and the through - holes of non - continuous periodic structure are 100μm - 500μm.

[0014] Further, the overall thickness of the three stacked and pasted wave - absorbing thin films is 30μm - 100μm.

[0015] According to the above - mentioned preparation method, the present invention also provides a wave - absorbing composite thin film, which includes two layers of wave - absorbing thin films with through - holes of continuous periodic structure and one layer of wave - absorbing thin film with through - holes of non - continuous periodic structure. The through - holes of continuous periodic structure and the through - holes of non - continuous periodic structure are both filled with thermal conductive adhesive. After the three layers of wave - absorbing thin films are stacked and pasted in sequence through the thermal conductive adhesive, the thermal conductive adhesives on the three layers of wave - absorbing thin films are connected to form a three - dimensional thermal conduction path.

[0016] Further, the real part of the dielectric of the substrate of the wave - absorbing thin film is 100 - 550, the loss angle is 0.1 - 0.5, the real part of the magnetic permeability is 0.1 - 5, and the loss angle is 2 - 8.

[0017] Further, the dimensions of both the through - holes of continuous periodic structure and the through - holes of non - continuous periodic structure are 100μm - 500μm.

[0018] Further, the overall thickness of the three layers of wave - absorbing thin films is 30μm - 100μm.

[0019] The present invention has the following advantages:

[0020] The wave-absorbing thin film with periodic structure through-holes has a good shielding effect on 2-8 GHz electromagnetic waves. At the same time, the three-layer wave-absorbing thin film constructs an internal three-dimensional heat conduction path through the thermal conductive adhesive, enabling the composite thin film to have better heat conduction ability. Description of the Drawings

[0021] Figure 1 It is a schematic structural diagram of three wave-absorbing thin films in the present invention;

[0022] Figure 2 It is a comparison chart of the wave-absorbing performance of the wave-absorbing composite thin film in the present invention;

[0023] Figure 3 It is a comparison chart of the heat conduction performance of the wave-absorbing composite thin film in the present invention. Detailed Embodiments

[0024] The following further describes the present invention with reference to the accompanying drawings, but the protection scope of the present invention is not limited to the following.

[0025] A preparation method of an interlocking high heat-conducting wave-absorbing composite thin film includes the following steps:

[0026] S1. Select three film substrates according to the wave-absorbing and reflection performances;

[0027] S2. Make two film substrates into wave-absorbing thin films with continuous periodic structure through-holes, and make one film substrate into a wave-absorbing thin film with discontinuous periodic structure through-holes, and fill the periodic structure through-holes with thermal conductive adhesive;

[0028] S3. Stack and paste the three wave-absorbing thin films in sequence through the thermal conductive adhesive, so that the thermal conductive adhesives on the three wave-absorbing thin films are connected to form a three-dimensional heat conduction path.

[0029] Specifically, in step S1, the film substrate is preferably a magnetic thin film. Since the larger the real part of the electromagnetic parameters of the magnetic thin film, the worse the material-air matching degree, the larger the reflectivity, and the better the shielding performance. And the imaginary part of the electromagnetic parameters is used to absorb electromagnetic waves, and the loss angle increases at high frequencies, and the electromagnetic wave loss increases. However, due to the film thickness problem, the reflection and shielding need to work together, and good wave absorption is achieved through multiple reflections and absorptions. Therefore, this technical solution preferably selects a magnetic thin film with a real part of the dielectric of 100-550, a loss angle of 0.1-0.5, a real part of the magnetic permeability of 0.1-5, and a loss angle of 2-8. Selecting a magnetic thin film with electromagnetic parameters within the above range can achieve wave transmission-wave absorption and sufficient reflection, enabling the magnetic thin film to reflect and absorb multiple times. In the actual preparation and material selection of the present invention, a magnetic thin film of 100mm*100mm, model MT-30, is specifically used. Its real part of the dielectric is 540 at 5.3 GHz, the corresponding imaginary part of the dielectric is 100, the real part of the magnetic permeability is 0.5, and the corresponding imaginary part of the magnetic permeability is 3.

[0030] In step S2, when preparing the microwave absorbing film with through-holes of a continuous periodic structure, a milling machine is used to engrave through-holes of a periodic structure on the surface of the film substrate according to the CAD design dimensions of the through-holes of the continuous periodic structure. Then, 0.03 mm thermal conductive adhesive is pasted on the surface of a metal plate coated with silicone oil centrifuging agent, and the milling machine is used to engrave the thermal conductive adhesive into the same shape as the through-holes of the continuous periodic structure. Finally, the excess thermal conductive adhesive is removed, and the film substrate is combined with the remaining part of the thermal conductive adhesive so that the thermal conductive adhesive fills the through-holes of the continuous periodic structure on the film substrate. The obtained microwave absorbing films are like the microwave absorbing film a and microwave absorbing film b shown in Figure 1 . In the figure, the x region is the through-holes of the continuous periodic structure filled with thermal conductive adhesive, and the y region is the film substrate.

[0031] When preparing the microwave absorbing film with through-holes of a discontinuous periodic structure, first, 0.1 mm thermal conductive adhesive is pasted on a metal plate, and the film substrate is pasted above the thermal conductive adhesive. The milling machine is used to cut the film substrate according to the CAD design dimensions of the through-holes of the discontinuous periodic structure. After cutting, the film substrate at the positions of the through-holes of the discontinuous periodic structure is taken out. Then, 0.03 mm thermal conductive adhesive is pasted on the surface of a metal plate coated with silicone oil centrifuging agent, and the milling machine is used to engrave the thermal conductive adhesive into the same shape as the through-holes of the discontinuous periodic structure. Finally, the excess thermal conductive adhesive is removed, and the remaining film substrate is combined with the remaining part of the thermal conductive adhesive so that the thermal conductive adhesive fills the through-holes of the discontinuous periodic structure on the film substrate. The obtained microwave absorbing film is like the microwave absorbing film c shown in Figure 1 . In the figure, the x region is the through-holes of the discontinuous periodic structure filled with thermal conductive adhesive, and the y region is the film substrate. Additionally, in the actual operation process of cutting the film substrate with the milling machine, the height of the milling machine is controlled to be 0.03 mm above the film substrate. After cutting, the thickness of the film substrate is reduced by at most 0.01 mm, but the thickness cannot be increased.

[0032] Preferably, the CAD design dimensions of both the through-holes of the continuous periodic structure and the through-holes of the discontinuous periodic structure are 100 μm - 500 μm. The size of the through-holes of the periodic structure on each layer of the microwave absorbing film will affect the microwave absorption and shielding performance of the thermally conductive and microwave absorbing composite film as well as the thermal conduction performance in the thickness direction. Specifically, when the size of the through-holes of the periodic structure exceeds 500 μm, the shielding ability of the microwave absorbing material will decrease significantly; if the size of the through-holes of the periodic structure is less than 100 μm, it will increase the die-cutting difficulty, and the periodic through-holes are too densely distributed, resulting in a decrease in the thermal conductivity of the material.

[0033] More preferably, the overall thickness of the three layers of microwave absorbing films stacked and pasted is 30 μm - 100 μm. Different thicknesses of microwave absorbing films are selected according to the electromagnetic parameters of different film substrates. In principle, as shown in Figure 2 、 3 , the thicker the thickness of the thermally conductive and microwave absorbing composite film, the better its microwave absorption performance, but the thermal conductivity of the material decreases.

[0034] The a, b, and c layers of microwave absorbing thin films obtained by the above preparation method Figure 1 are sequentially laminated and pasted with heat-conducting adhesive, thereby obtaining a microwave absorbing composite thin film. The heat-conducting adhesive at the periodic structure through-holes on the three layers of microwave absorbing thin films connects to form a three-dimensional heat conduction path. Through this structural design combined with the electromagnetic principles (effective medium theory and microwave absorption theory) of the thin film substrate, the microwave absorbing composite thin film not only has high heat conduction performance but also can produce an ideal shielding effect on electromagnetic waves in the range of 2 - 8 GHz through the reflection and absorption of the microwave absorbing thin films.

[0035] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A preparation method of an interlocking high thermal conductivity and wave-absorbing composite film, characterized in that, It includes the following steps: S1. Select three film substrates according to the wave absorption and reflection performance; S2. Make two film substrates into wave-absorbing films with through-holes of continuous periodic structure, and make one film substrate into a wave-absorbing film with through-holes of discontinuous periodic structure. The heat-conducting glue is filled in the through-holes of the periodic structure. The CAD design dimensions of the through-holes of the continuous periodic structure and the through-holes of the discontinuous periodic structure are both 100μm - 500μm; S3. Stack and paste the three wave-absorbing films in sequence through the heat-conducting glue, so that the heat-conducting glue on the three wave-absorbing films is connected to form a three-dimensional heat-conducting path.

2. The preparation method of the interlocking high thermal conductivity wave-absorbing composite film and the wave-absorbing composite film according to claim 1, characterized in that: In step S1, the film substrate is a magnetic film, and the electromagnetic parameters of the film substrate are that the real part of the dielectric is 100 - 550, the loss angle is 0.1 - 0.5, the real part of the magnetic permeability is 0.1 - 5, and the loss angle is 2 - 8.

3. The preparation method of the interlocking high thermal conductivity wave-absorbing composite film and the wave-absorbing composite film according to claim 1, wherein: In step S2, when preparing the wave-absorbing film with through-holes of continuous periodic structure, use a engraving machine to engrave through-holes of periodic structure on the surface of the film substrate according to the CAD design dimensions of the through-holes of the continuous periodic structure. Then paste 0.03mm heat-conducting glue on the surface of a metal plate coated with silicone oil centrifugal agent, and use a engraving machine to engrave the heat-conducting glue into the same shape as the through-holes of the continuous periodic structure. Finally, remove the excess heat-conducting glue, and combine the film substrate with the remaining part of the heat-conducting glue, so that the heat-conducting glue fills the through-holes of the continuous periodic structure on the film substrate.

4. The preparation method of the interlocked high thermal conductivity wave-absorbing composite film and the wave-absorbing composite film according to claim 3, wherein: In step S2, when preparing the wave-absorbing film with through-holes of discontinuous periodic structure, first paste 0.1mm heat-conducting glue on the metal plate and paste the film substrate above the heat-conducting glue. Use a engraving machine to cut the film substrate according to the CAD design dimensions of the through-holes of the discontinuous periodic structure. After cutting, take out the film substrate at the position of the through-holes of the discontinuous periodic structure. Then paste 0.03mm heat-conducting glue on the surface of a metal plate coated with silicone oil centrifugal agent, and use a engraving machine to engrave the heat-conducting glue into the same shape as the through-holes of the discontinuous periodic structure. Finally, remove the excess heat-conducting glue, and combine the remaining film substrate with the remaining part of the heat-conducting glue, so that the heat-conducting glue fills the through-holes of the discontinuous periodic structure on the film substrate.

5. The preparation method of the interlocking high thermal conductivity wave-absorbing composite film and the wave-absorbing composite film according to claim 1, characterized in that: The overall thickness after the three wave-absorbing films are stacked and pasted is 30μm - 100μm.

6. An electromagnetic wave absorbing composite film, characterized in that: It includes two wave-absorbing films with through-holes of continuous periodic structure and one wave-absorbing film with through-holes of discontinuous periodic structure. The heat-conducting glue is filled in both the through-holes of the continuous periodic structure and the through-holes of the discontinuous periodic structure. The sizes of the through-holes of the continuous periodic structure and the through-holes of the discontinuous periodic structure are both 100μm - 500μm. After the three wave-absorbing films are stacked and pasted in sequence through the heat-conducting glue, the heat-conducting glue on the three wave-absorbing films is connected to form a three-dimensional heat-conducting path.

7. The absorbing composite film according to claim 6, wherein: The electromagnetic parameters of the substrate of the wave-absorbing film are that the real part of the dielectric is 100 - 550, the loss angle is 0.1 - 0.5, the real part of the magnetic permeability is 0.1 - 5, and the loss angle is 2 - 8.

8. The microwave absorbing composite film according to claim 6, wherein: The overall thickness of the three wave-absorbing films is 30μm - 100μm.

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