A thermal conductive interface material and its preparation method and application

Abstract

The present invention relates to a thermally conductive interface material, its preparation method, and its application. The preparation method comprises the following steps: sequentially subjecting a blank to a first orientation, a second orientation, and curing to obtain the thermally conductive interface material. The thermally conductive interface material obtained by the preparation method has high thermal conductivity, high resilience, low hardness, and excellent aging resistance. Furthermore, the preparation method is simple, highly efficient, and low-cost.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal conductive interface materials, and in particular to a thermal conductive interface material and a preparation method and application thereof. Background Art

[0002] At present, thermal conductive gaskets can be divided into two basic categories. One is thermal conductive silicone gaskets filled with insulating high thermal conductivity powders such as alumina and boron nitride. The other is oriented high thermal conductivity gaskets based on carbon materials with high thermal conductivity that are oriented to enhance thermal conductivity.

[0003] CN 112976438A discloses a method for preparing a directionally interconnected high-thermal-conductivity interface material and its product. The method comprises the following steps: S1: adding filler particles to a mold, placing the mold in a permanent magnetic field, and applying vibration to the mold, causing the filler particles to automatically align and arrange in the magnetic field under vibration, forming a filler particle array; S2: maintaining the permanent magnetic field, injecting a thermosetting polymer colloid into the mold, vacuuming the mold to remove air, allowing the thermosetting polymer colloid to fill the gaps in the filler particle array, and then heating and curing to obtain the desired directionally interconnected high-thermal-conductivity interface material.

[0004] CN 112712995A discloses a method for preparing a highly oriented magnetic absorbing film, comprising the following steps: S1. Preparing a magnetic absorber slurry; S2. Preparing a magnetic film; S3. Orienting the magnetic film: Before drying, subjecting the prepared magnetic film to a high-frequency converted periodic magnetic field for magnetic field orientation; subjecting the magnetic film to a high-frequency converted periodic magnetic field in a single-cycle, multi-cycle, parallel, or cross-arranged pattern, causing the magnetic absorber powder to vibrate at high speed and move parallel to the film strip; S4. Drying the magnetic film; and S5. Forming the magnetic film. By orienting the magnetic absorbing film with a high-frequency periodic magnetic field, the film achieves improved orientation, allowing the preparation of a highly oriented magnetic film without the use of large-scale, high-pressure lamination equipment, thereby improving the magnetic permeability and magnetic loss of the film.

[0005] Thermally conductive silicone gaskets use a high filling ratio powder to increase the thermal conductivity of the thermal conductive gasket. Under the current state of the art, the thermal conductivity of thermal conductive gaskets is typically between 1-15W / m·K. In products with a thermal conductivity higher than 5W, it is often difficult to achieve mechanical properties such as a high compression ratio, soft hardness, and high rebound. Furthermore, the large amount of powder filling in the product limits its overall anti-aging properties. Highly thermally conductive oriented carbon fiber gaskets typically have a thermal conductivity of 20-60W / m·K. However, due to the large amount of carbon fiber filling used to enhance and achieve thermal conductivity through orientation, their overall compressibility suffers from certain deficiencies, and the product's hardness cannot be made too soft. Furthermore, due to the particularity of the orientation process, it is difficult to achieve low costs and high production efficiency in large-scale, rapid production of oriented products.

[0006] Currently, with the increasing functional demands for electronic chips in various fields and the corresponding increase in power density, the widespread application of high-performance, high-power chips has led to an increase in the overall application demand for thermal interface materials, and on this basis, a high demand for the overall cost of interface materials. Based on usage characteristics, the commonly used 2W-6W range is gradually increasing to the 5W-15W range, and the requirements are soft, hard, and low production costs. However, traditional thermally conductive silicone gaskets and oriented high-thermal conductivity gaskets cannot meet these requirements.

[0007] The main features of thermal interface materials at this stage are: 1. The application range of thermal conductivity coefficient is increased from 2-6W to 5-15W; 2. The overall hardness of the product is required to be soft, generally in the SHORE C 5-30° range; 3. The application cost of thermal interface materials is required to be reduced, which is equivalent to the price of ordinary thermal conductive silicone gaskets; 4. The product rebound characteristics are required to be good, and after long-term reliability testing, it can still maintain a rebound rate of more than 80%; 5. The product production efficiency is required to be equivalent to that of traditional thermal conductive silicone gaskets; 6. The product density is relatively low, less than 3.2g / cm 3 ; 7. The product thickness application range is 0.2-10mm.

[0008] The main problems with thermal interface materials at this stage are: 1. Thermal conductive silicone gaskets have poor hardness performance, low rebound rate, high product density, and poor anti-aging properties in high-wattage products greater than 5W; 2. Oriented high-thermal conductive gaskets also have the problems of high hardness, high price, complicated production process, and low production efficiency in application.

[0009] In summary, it is crucial to develop a preparation method that can solve the technical problems faced by existing thermal conductive interface materials. Summary of the Invention

[0010] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a thermal conductive interface material and its preparation method and application. The thermal conductive interface material formed by the preparation method of the thermal conductive interface material has the characteristics of high thermal conductivity, high rebound, low hardness and excellent anti-aging performance, and the preparation method is simple, the production efficiency is high and the cost is low.

[0011] To achieve this object, the present invention adopts the following technical solutions:

[0012] In a first aspect, the present invention provides a method for preparing a thermally conductive interface material, the method comprising the following steps:

[0013] The blank is sequentially subjected to a first orientation, a second orientation and solidification to obtain the thermally conductive interface material.

[0014] The preparation method of the present invention combines multiple process technologies to achieve the production of thermal interface materials that can solve current application problems; the method has many characteristics such as simple principle, easy implementation, high stability and consistency, and can achieve large-scale and efficient production based on a certain degree of modification of existing general equipment.

[0015] In the present invention, the disordered blank is oriented in a certain direction by the first orientation, and then oriented in a direction different from the first orientation by the second orientation, and then solidified to form a solid that can be transferred and taken away, thereby obtaining the thermal interface material.

[0016] Preferably, the viscosity of the blank is 2000-100000 mPa·S, for example, 3000 mPa·S, 4000 mPa·S, 5000 mPa·S, 6000 mPa·S, 7000 mPa·S, 8000 mPa·S, 9000 mPa·S, 10000 mPa·S, 20000 mPa·S, 40000 mPa·S, 60000 mPa·S, 80000 mPa·S, etc.

[0017] Preferably, the blank includes silicone rubber, fiber thermal conductive material, other thermal conductive fillers and magnetic conductive fillers.

[0018] In the present invention, a magnetic conductive filler is added to the basic formula to enhance the force effect of the fiber thermal conductive material in the second orientation. In addition, an electromagnetic wave absorption effect based on hysteresis consumption can also be formed.

[0019] Preferably, the fiber thermal conductive material includes carbon fibers.

[0020] Preferably, the carbon fiber comprises any one of pitch-based carbon fiber, polyacrylonitrile-based carbon fiber, viscose-based carbon fiber, phenolic-based carbon fiber, or vapor-grown carbon fiber, or a combination of at least two thereof, wherein typical but non-limiting combinations include: a combination of pitch-based carbon fiber and polyacrylonitrile-based carbon fiber, a combination of viscose-based carbon fiber and phenolic-based carbon fiber, a combination of polyacrylonitrile-based carbon fiber, viscose-based carbon fiber, phenolic-based carbon fiber, and vapor-grown carbon fiber, etc. Preferably, the average length of the fibrous thermal conductive filler is 100-250 μm, for example, 120 μm, 140 μm, 160 μm, 180 μm, 200 μm, 220 μm, 240 μm, etc.

[0021] Preferably, the diameter of the fiber thermal conductive filler is 5-10 μm, for example, 6 μm, 7 μm, 8 μm, 9 μm, etc.

[0022] Preferably, the other thermally conductive fillers include any one or a combination of at least two of aluminum oxide, boron nitride or graphene, wherein typical but non-limiting combinations include: a combination of aluminum oxide and boron nitride, a combination of boron nitride and graphene, a combination of aluminum oxide, boron nitride and graphene, etc.

[0023] Preferably, the magnetic conductive filler comprises a soft magnetic material.

[0024] Preferably, the particle size of the magnetic conductive filler is ≤10 μm, for example, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, etc.

[0025] Preferably, the magnetic conductive filler includes hydroxy iron powder and / or sendust powder.

[0026] Preferably, based on the total mass of the blank as 100%, the mass percentage of the fiber thermal conductive filler is ≤50%, for example, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 5%, etc.

[0027] In the present invention, the mass percentage of the fiber thermal conductive filler needs to be controlled within the range of ≤50%. Exceeding this range will cause difficulties in the orientation operation, that is, a longer magnetic field influence time will be required, and the viscosity of the blank will be too high, even exceeding 80,000 mPa·s.

[0028] Preferably, based on the total mass of the blank being 100%, the mass percentage of the magnetic conductive filler is ≤30%, for example, 25%, 20%, 15%, 5%, etc.

[0029] In the present invention, the mass percentage of the magnetic conductive filler needs to be controlled within a range of ≤30%. Exceeding this range may easily cause the material to transfer to the interface end during magnetic field orientation.

[0030] Preferably, based on the total mass of the blank as 100%, the mass percentage of the other thermally conductive particles is ≤60%, for example 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 5%, etc.

[0031] In the present invention, the mass percentage of other thermally conductive fillers needs to be controlled within the range of ≤60%. Exceeding this range will cause a decrease in the thermal conductivity coefficient, and further cause the problem of excessive viscosity after adding carbon fiber, resulting in the thermal conductive interface material being too high and unable to meet the requirements.

[0032] Preferably, the weight proportion of the organic silicone rubber is 200-300 parts, such as 220 parts, 240 parts, 260 parts, 280 parts, etc.

[0033] Preferably, the weight proportion of the fiber thermal conductive filler is 100-200 parts, for example, 120 parts, 140 parts, 160 parts, 180 parts, etc.

[0034] Preferably, the weight proportion of the other thermally conductive filler is 300-400 parts, such as 320 parts, 340 parts, 360 parts, 380 parts, etc.

[0035] Preferably, the weight proportion of the magnetic conductive material is 200-300 parts, such as 22 parts, 240 parts, 26 parts, 280 parts, etc.

[0036] Preferably, the first orientation method includes any one of rod coating, blade coating or casting, or a combination of at least two of them, wherein typical but non-limiting combinations include: a combination of rod coating and blade coating, a combination of blade coating and casting, a combination of rod coating, blade coating and casting, etc.

[0037] In the present invention, the first orientation method includes one or more combinations of rod coating, blade coating or casting, which mainly utilizes the fluid shear force to achieve orientation of the material with physical size characteristics in the mixed fluid in the direction of the forward force.

[0038] Preferably, the thickness of the blank after the first orientation is 0.1-3 mm, such as 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, etc., more preferably 0.3-0.6 mm.

[0039] In the present invention, the thickness of the first oriented blank is 0.1-3mm. If the thickness is too thick, the fluid shear force will gradually decrease, until the side near the base film becomes completely unoriented. In principle, the thinner the blank, the better the orientation effect, except for the problem of material not being able to pass through.

[0040] Preferably, the second orientation method includes physical vibration and magnetic field orientation.

[0041] In the present invention, the second orientation method includes physical vibration and magnetic field orientation. Physical vibration can be high-frequency or low-frequency as needed, and its main function is to reduce the adhesion of the fiber material to the blank, facilitating magnetic field orientation. Magnetic field orientation utilizes the principle that diamagnetic materials in a strong magnetic field will generate a deflection force. By placing the fiber material in a strong magnetic field, the fiber material can be oriented in the direction of the magnetic field lines.

[0042] Preferably, the frequency of the physical vibration is 20-100 Hz (for example, 30 Hz, 40 Hz, 50 Hz, 60 Hz, 70 Hz, 80 Hz, 90 Hz, etc.) or 5-30 kHz (for example, 6 kHz, 8 kHz, 10 kHz, 2 kHz, 14 kHz, 16 kHz, 18 kHz, 20 kHz, 22 kHz, 24 kHz, 26 kHz, 28 kHz, etc.).

[0043] In the present invention, the frequency of the physical vibration is selected to match the viscosity of the material. For materials with higher viscosity, a higher frequency vibration mode is selected to produce a better orientation effect.

[0044] Preferably, the intensity of the magnetic field orientation is 0.3-5T, such as 0.5T, 1T, 1.5T, 2T, 2.5T, etc.

[0045] Preferably, the first orientation and the second orientation are in different directions.

[0046] In the present invention, it is preferred that the direction of the first alignment and the direction of the second alignment are perpendicular to each other.

[0047] Preferably, when the second orientation is performed, the blank advances along a direction different from that of the second orientation.

[0048] In the present invention, the second orientation method is preferably conducive to short-term straightening by magnetic force and forward force, which is more conducive to controlling the orientation angle and improving the orientation efficiency compared to the conventional long-term gradual straightening using magnetic force.

[0049] Preferably, the forward speed is 0.5-1.5 m / min, for example, 0.6 m / min, 0.8 m / min, 1 m / min, 1.2 m / min, 1.4 m / min, etc.

[0050] Preferably, the curing method includes heat curing.

[0051] In the present invention, heat curing is used to not only form a solid that can be transferred and taken out, but also to maintain the orientation direction of the fiber thermal conductive material from falling over, forming a thermal conductive path different from the first orientation method.

[0052] Preferably, the temperature of the heating and curing is 85-160°C, such as 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, etc., more preferably 110°C.

[0053] Preferably, the heating and curing time is 3-30 minutes, such as 5 minutes, 10 minutes, 20 minutes, etc.

[0054] Preferably, after solidification, the process further comprises stacking the obtained blanks.

[0055] In the present invention, the heated and solidified blanks can be selectively stacked according to the thickness requirements of different thermally conductive pads.

[0056] For example, a strip of polyethylene terephthalate (PET) with a release liner is treated with a surface treatment agent. The coated strips are then laminated together, and the lamination process is repeated until the desired thickness is reached. This creates a thermally conductive gasket product with adhesive properties and varying thicknesses. Alternatively, a single layer can be used directly as a gasket without stacking. In this case, the thickness of the first orientation is used as the final thickness of the gasket.

[0057] It should be noted that the purpose of the stacking setting is to increase the thickness of the oriented gasket material at the application end, and the participation of PET is not required. In actual operation, the PET needs to be peeled off. Only the bottom gasket needs to be attached with this layer of PET to ensure that the soft gasket has a load-bearing capacity and is not deformed by pulling. Soft objects are easy to stick to other workpieces and are difficult to remove. Therefore, the bottom PET also needs to be present with the gasket, but this is not necessary for the layer-by-layer stacking of blanks.

[0058] Preferably, the stacking method includes bonding.

[0059] As a preferred technical solution, the preparation method comprises the following steps:

[0060] (1) mixing silicone rubber, fiber thermal conductive material, other thermal conductive fillers and magnetic conductive fillers to form a blank with a viscosity of 2000-10000 mPa·s;

[0061] (2) orienting the blank obtained in step (1) by any one of rod coating, blade coating or casting or a combination of at least two thereof to form a blank with a thickness of 0.1-3 mm;

[0062] (3) advancing the blank obtained in step (2) at a speed of 0.5-1.5 m / min, and performing physical vibration at a frequency of 20-100 Hz or 5-30 kHz, and simultaneously performing magnetic field orientation at an intensity of 0.3-5 T, controlling the time of physical vibration and magnetic field orientation to be 5-10 s, and the direction of magnetic field orientation is different from the direction of the blank advancement and the first orientation, thereby completing the second orientation;

[0063] (4) heating and curing the blank obtained in step (3) at 85-160° C. for 3-30 min to obtain the thermal conductive interface material;

[0064] or

[0065] The blank obtained in step (3) is heated and cured at 85-160° C. for 3-30 minutes, and the heated and cured blanks are stacked to obtain the thermal conductive interface material.

[0066] In the prior art, the process of orienting the blank directly using its diamagnetic properties is usually difficult because the fiber thermal conductive materials in the mixture, such as carbon fibers, are disorderly arranged and their diamagnetic properties make them relatively less susceptible to magnetic forces.

[0067] In the present invention, by pre-orienting the fiber thermal conductive material in one direction, the disorder in the blank is greatly reduced, which in turn greatly promotes the magnetic field orientation in the second orientation. By orienting in two directions in sequence, the overall orientation efficiency of the fiber thermal conductive material can be effectively improved.

[0068] In addition, the present invention further increases the role and effect of magnetic field orientation by adding magnetic conductive materials and increasing physical vibration. The effect of physical vibration is mainly to eliminate the viscous effect of liquid glue on the fiber thermal conductive material and reduce the difficulty of orientation of the fiber thermal conductive material. In addition to enhancing the orientation effect, the use of soft magnetic materials also has the function of absorbing electromagnetic waves. The addition of magnetic conductive materials and the forward direction of the blank (the direction of the first orientation) jointly generate a force, that is, the PET is continuously dragged in the axial direction of the first orientation, which can further promote the material under the condition of magnetic field force, that is, the fiber exhibits antimagnetic properties and deflects under the magnetic field. At this time, the dragging force is used to further utilize the driving force of the colloid to push the fiber straight; that is, there are three types of second orientation forces, antimagnetic force, magnetic material movement force, and the thrust on the carbon fiber formed by the colloid being dragged forward on the PET; through the above operation, the fiber thermal conductive material is pushed in the direction of the magnetic field line, which further produces an orientation effect.

[0069] In a second aspect, the present invention provides a thermally conductive interface material, which is prepared by the preparation method described in the first aspect.

[0070] In a third aspect, the present invention provides an electronic chip, comprising the thermal interface material described in the second aspect.

[0071] Compared with the prior art, the present invention has the following beneficial effects:

[0072] (1) The thermal interface material obtained by the preparation method of the present invention has the characteristics of high thermal conductivity, high rebound, low hardness and excellent anti-aging performance, and the preparation method is simple, the production efficiency is high and the cost is low;

[0073] (2) The thermal conductivity of the thermal interface material obtained by the preparation method of the present invention is above 7.2W / (m·K), the rebound rate is above 76%, the hardness is between 30-32°, and the density is 3.4g / cm 3 Below, after aging, the hardness is between 30-36°, the rebound rate is above 65%, the thermal conductivity is above 7.0W / (m·K), the average orientation rate of the first orientation with a horizontal deflection angle of less than 20° is above 90%, the average orientation rate of the second orientation with a vertical deflection angle of less than 20° is above 80%, and the production speed is above 0.8 m / min. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] Figure 1 is a schematic diagram of the orientation process of the thermal interface material described in Example 1;

[0075] Figure 2 is a simplified schematic diagram of the orientation process of the thermal interface material described in Example 2;

[0076] Figure 3 is a structural diagram of an apparatus for preparing the thermally conductive interface material of the present invention;

[0077] Among them, 1-working table; 2-baffle; 3-coating knife; 4-magnetic field generator; 5-vibration generator; 6-magnetic head; 7-vibration conduction plate; 8-heating table. DETAILED DESCRIPTION

[0078] For the convenience of understanding the present invention, the present invention is given below with examples. It should be understood by those skilled in the art that the examples are only for the purpose of helping to understand the present invention and should not be regarded as specific limitations of the present invention.

[0079] Example 1

[0080] This embodiment provides a method for preparing a thermally conductive interface material, the method comprising the following steps:

[0081] (1) 200 parts by weight of silicone rubber, 200 parts by weight of carbon fiber, 350 parts of fumed alumina, and 250 parts of hydroxy iron powder were mixed to form a blank having a viscosity of 60,000 mPa·s;

[0082] (2) orienting the blank obtained in step (1) by a combination of rod coating and blade coating to form a blank with a thickness of 0.5 mm;

[0083] (3) The blank obtained in step (2) is advanced at a speed of 0.8 m / min and subjected to physical vibration at a frequency of 20 kHz and magnetic field orientation at an intensity of 1 T to complete the second orientation;

[0084] (4) The blank obtained in step (3) is heated and cured at 85° C. for 30 minutes to obtain the thermal conductive interface material.

[0085] In this embodiment, the information of each raw material is as follows:

[0086] Silicone rubber: transparent vinyl liquid silicone rubber with a viscosity of 2000 mPa·s, purchased from a Dow Corning brand agent, brand 1107A;

[0087] Carbon fiber: pitch-based chopped carbon fiber, average length 200 μm, fiber diameter 10 μm, purchased from Mitsubishi Chemical, brand K223HM PITCH 90t;

[0088] Fumed alumina: average particle size 10 μm;

[0089] Hydroxy iron powder: average particle size is 5nm.

[0090] Taking this embodiment as an example, during preparation, the orientation process change diagram of the thermal interface material is as follows: Figure 1 and Figure 2 As shown, when magnetic field orientation is carried out in a chaotic state, there will be obstacles of horizontal and vertical interlacing. The first orientation has reduced the influence of weak magnetic field force that blocks the orientation. After the first direction is combed, the vertical head can reduce almost 90% of the interlacing obstacles. Carbon-based material is a material with antimagnetic properties. Under a strong magnetic field, it will succumb to the direction of the magnetic line of force and be oriented, thereby obtaining the highly oriented thermal conductive interface material described in the present invention.

[0091] Taking this embodiment as an example, the structural diagram of the device used is as follows Figure 3 As shown, the blank is first oriented on the workbench 1, wherein the baffle 2 prevents the blank from overflowing, and the coating knife 3 performs rod coating and scraping coating. After the first orientation is completed, the second orientation is performed while moving forward, wherein the magnetic field generator 4 and the magnetic head 6 are used for magnetic field orientation, and at the same time, the vibration generator 5 and the vibration conduction sheet 7 are used for physical vibration. After the second orientation is completed, it enters the heating table 8 for curing.

[0092] Example 2

[0093] This embodiment provides a method for preparing a thermally conductive interface material, the method comprising the following steps:

[0094] (1) 250 parts by weight of silicone rubber, 150 parts by weight of carbon fiber, 300 parts of fumed alumina, and 300 parts of hydroxy iron powder were mixed to form a blank having a viscosity of 45,000 mPa·s;

[0095] (2) orienting the blank obtained in step (1) by a combination of rod coating and tape casting to form a blank with a thickness of 0.3 mm;

[0096] (3) The blank obtained in step (2) is advanced at a speed of 0.8 m / min and subjected to physical vibration at a frequency of 100 Hz, while being oriented in a magnetic field at an intensity of 1 T to complete the second orientation;

[0097] (4) The blank obtained in step (3) is heated and cured at 85° C. for 30 minutes to obtain the thermal conductive interface material.

[0098] In this embodiment, the information of each raw material is as follows:

[0099] Silicone rubber: transparent vinyl liquid silicone rubber with a viscosity of 2000 mPa·s, purchased from a Dow Corning brand agent, brand 1107A;

[0100] Carbon fiber: pitch-based chopped carbon fiber, average length 200 μm, fiber diameter 10 μm, purchased from Mitsubishi Chemical, brand K223HM PITCH 90t;

[0101] Fumed alumina: average particle size 10 μm;

[0102] Hydroxy iron powder: average particle size is 50nm.

[0103] Example 3

[0104] This embodiment provides a method for preparing a thermally conductive interface material, the method comprising the following steps:

[0105] (1) 300 parts by weight of silicone rubber, 100 parts by weight of carbon fiber, 400 parts of fumed alumina, and 200 parts of hydroxy iron powder were mixed to form a blank having a viscosity of 36,000 mPa·s;

[0106] (2) orienting the blank obtained in step (1) by a combination of rod coating and blade coating to form a blank with a thickness of 2 mm;

[0107] (3) The blank obtained in step (2) is advanced at a speed of 0.8 m / min and subjected to physical vibration at a frequency of 100 Hz, while being oriented in a magnetic field at an intensity of 1 T to complete the second orientation;

[0108] (4) The blank obtained in step (3) is heated and cured at 85° C. for 30 minutes to obtain the thermal conductive interface material.

[0109] In this embodiment, the information of each raw material is as follows:

[0110] Silicone rubber: transparent vinyl liquid silicone rubber with a viscosity of 2000 mPa·s, purchased from a Dow Corning brand agent, brand 1107A;

[0111] Carbon fiber: pitch-based chopped carbon fiber, average length 200 μm, fiber diameter 10 μm, purchased from Mitsubishi Chemical, brand K223HM PITCH 90t;

[0112] Fumed alumina: average particle size 10 μm;

[0113] Hydroxy iron powder: average particle size is 50nm.

[0114] Example 4

[0115] This embodiment provides a method for preparing a thermally conductive interface material, the method comprising the following steps:

[0116] (1) 350 parts by weight of silicone rubber, 100 parts by weight of carbon fiber, 350 parts of fumed alumina, and 200 parts of hydroxy iron powder were mixed to form a blank having a viscosity of 20,000 mPa·s;

[0117] (2) orienting the blank obtained in step (1) by a combination of rod coating and blade coating to form a blank with a thickness of 0.3 mm;

[0118] (3) The blank obtained in step (2) is advanced at a speed of 0.8 m / min and subjected to physical vibration at a frequency of 100 Hz, while being oriented in a magnetic field at an intensity of 1 T to complete the second orientation;

[0119] (4) The blank obtained in step (3) was heated and cured at 110° C. for 6 min to obtain the thermal conductive interface material. In this embodiment, the information of each raw material is the same as that in Example 1.

[0120] Example 5

[0121] This embodiment provides a method for preparing a thermally conductive interface material, the method comprising the following steps:

[0122] (1) 300 parts by weight of silicone rubber, 100 parts by weight of carbon fiber, 400 parts of fumed alumina, and 200 parts of hydroxy iron powder were mixed to form a blank having a viscosity of 32,000 mPa·s;

[0123] (2) orienting the blank obtained in step (1) by a combination of rod coating and blade coating to form a blank with a thickness of 3 mm;

[0124] (3) The blank obtained in step (2) is advanced at a speed of 0.8 m / min and subjected to physical vibration at a frequency of 100 Hz, while being oriented in a magnetic field at an intensity of 1 T to complete a second orientation;

[0125] (4) The blank obtained in step (3) is heated and cured at 130° C. for 4 minutes to obtain the thermal conductive interface material.

[0126] In this embodiment, the information of each raw material is the same as that in Example 1.

[0127] Example 6

[0128] This embodiment provides a method for preparing a thermally conductive interface material, the method comprising the following steps:

[0129] (1) 300 parts by weight of silicone rubber, 100 parts by weight of carbon fiber, 400 parts of fumed alumina, and 200 parts of hydroxy iron powder were mixed to form a blank having a viscosity of 30,000 mPa·s;

[0130] (2) orienting the blank obtained in step (1) by a combination of rod coating and blade coating to form a blank with a thickness of 2 mm;

[0131] (3) the blank obtained in step (2) is advanced at a speed of 1 m / min and subjected to physical vibration at a frequency of 100 Hz, while being oriented in a magnetic field at an intensity of 1 T, and the direction of the magnetic field orientation is different from the direction of the blank advancement and the first orientation, thereby completing the second orientation;

[0132] (4) The blank obtained in step (3) is heated and cured at 110° C. for 8 minutes to obtain the thermal conductive interface material.

[0133] In this embodiment, the information of each raw material is the same as that in Example 1.

[0134] Example 7

[0135] This embodiment provides a method for preparing a thermally conductive interface material, the method comprising the following steps:

[0136] (1) 350 parts by weight of silicone rubber, 150 parts by weight of carbon fiber, 200 parts of fumed alumina, and 200 parts of hydroxy iron powder were mixed to form a blank having a viscosity of 25,000 mPa·s;

[0137] (2) orienting the blank obtained in step (1) by a combination of rod coating and blade coating to form a blank with a thickness of 1.5 mm;

[0138] (3) the blank obtained in step (2) is advanced at a speed of 0.8 m / min and subjected to physical vibration at a frequency of 100 Hz, while being oriented in a magnetic field at an intensity of 1 T, and the direction of the magnetic field orientation is different from the direction of the blank advancement and the first orientation, thereby completing the second orientation;

[0139] (4) The blank obtained in step (3) is heated and cured at 110° C. for 6 minutes to obtain the thermal conductive interface material.

[0140] In this embodiment, the information of each raw material is the same as that in Example 1.

[0141] Example 8

[0142] The difference between this embodiment and embodiment 1 is that step (4) further includes stacking two layers of the heated and solidified blanks, and the rest is the same as embodiment 1.

[0143] Comparative Example 1

[0144] The difference between this comparative example and Example 1 is that the first orientation is not performed, the blank is formed by spin coating in step (1), and the rest is the same as Example 1.

[0145] Performance Testing

[0146] The thermal interface materials described in Examples 1-8 and Comparative Example 1 were tested as follows:

[0147] (1) Hardness (Shore C): carried out in accordance with ASTM D 2240.

[0148] (2) Rebound rate: According to ASTM D 412.

[0149] (3) Density: in accordance with ASTM D 792.

[0150] (4) Anti-aging performance: After 1000 hours of hot and cold cycles, the hardness, rebound rate and thermal conductivity of the thermal interface material are tested.

[0151] (5) Thermal conductivity: in accordance with ASTM D 5470.

[0152] (6) First orientation rate: The first orientation rate was measured by a two-dimensional projection analyzer, with a horizontal deflection angle of less than 20° as the orientation direction, and the average orientation rate was calculated.

[0153] (2) Second orientation rate: The second orientation rate was tested by a two-dimensional projection analyzer, with a vertical deflection angle of less than 20° as the orientation direction, and the average orientation rate was calculated.

[0154] The test results are summarized in Table 1-2.

[0155] Table 1

[0156]

[0157] Table 2

[0158]

[0159] Analysis of the data in Table 1 shows that the thermal interface material obtained by the preparation method of the present invention has the characteristics of high thermal conductivity, high rebound, low hardness and excellent anti-aging performance, and the preparation method is simple, the production efficiency is high and the cost is low; the thermal interface material obtained by the preparation method of the present invention has a thermal conductivity of more than 7.2W / (m·K), a rebound rate of more than 76%, a hardness of 30-32° (the hardness can be adjusted to between 5-35° as needed), and a density of 3.4g / cm 3 Below, after aging, the hardness is between 30-36° (the hardness can be adjusted to between 5-40° as needed), the rebound rate is above 65%, the thermal conductivity is above 7.0W / (m·K), the average orientation rate of the first orientation with a horizontal deflection angle of less than 20° is above 90%, the average orientation rate of the second orientation with a vertical deflection angle of less than 20° is above 80%, and the production speed is above 0.8 m / min.

[0160] Analysis of Comparative Example 1 and Example 1 shows that the performance of Comparative Example 1 is not as good as that of Example 1, which proves that the thermal interface material formed by the method of the present invention has better performance. Among them, the first orientation rate is too low to be counted.

[0161] The applicant states that the present invention is intended to illustrate the detailed methods of the present invention through the above-described embodiments, but the present invention is not limited to the above-described detailed methods, that is, it does not mean that the present invention must rely on the above-described detailed methods in order to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for various raw materials in the products of the present invention, addition of auxiliary ingredients, and selection of specific methods, etc., are all within the scope of protection and disclosure of the present invention.

Claims

1. A method for preparing a thermally conductive interface material, characterized in that: The preparation method comprises the following steps: The blank is sequentially subjected to a first orientation, a second orientation, and solidification to obtain the thermally conductive interface material; The blank includes organic silicone rubber, fiber thermal conductive material, other thermal conductive fillers and magnetic conductive fillers; The magnetic conductive filler comprises a soft magnetic material; The first orientation method includes any one of rod coating, blade coating or casting, or a combination of at least two thereof; The second orientation method includes physical vibration and magnetic field orientation; The first orientation and the second orientation are in different directions; When the second orientation is carried out, the blank advances in a direction different from the second orientation; The direction in which the blank advances is the direction of the first orientation; The forward speed is 0.5-1.5 m / min; The viscosity of the blank is 2000-100000 mPa·S.

2. The preparation method according to claim 1, characterized in that The fiber heat conductive material includes carbon fiber.

3. The preparation method according to claim 2, characterized in that The carbon fiber includes any one of pitch-based carbon fiber, polyacrylonitrile-based carbon fiber, viscose-based carbon fiber, phenolic-based carbon fiber or vapor-grown carbon fiber, or a combination of at least two thereof.

4. The preparation method according to claim 1, characterized in that The average length of the fiber thermal conductive material is 100-250 μm.

5. The preparation method according to claim 1, characterized in that The diameter of the fiber thermal conductive material is 5-10 μm.

6. The preparation method according to claim 1, characterized in that The other thermally conductive fillers include any one of aluminum oxide, boron nitride or graphene, or a combination of at least two of them.

7. The preparation method according to claim 1, characterized in that The particle size of the magnetic conductive filler is ≤10 μm.

8. The preparation method according to claim 1, characterized in that The magnetic conductive filler includes hydroxy iron powder and / or sendust powder.

9. The preparation method according to claim 1, characterized in that Taking the total mass of the blank as 100%, the mass percentage of the fiber thermal conductive material is ≤50%.

10. The preparation method according to claim 1, characterized in that Taking the total mass of the blank as 100%, the mass percentage of the magnetic conductive filler is ≤30%.

11. The preparation method according to claim 1, characterized in that Taking the total mass of the blank as 100%, the mass percentage of the other thermally conductive fillers is ≤60%.

12. The preparation method according to claim 1, characterized in that The weight proportion of the organic silicone rubber is 200-300 parts.

13. The preparation method according to claim 1, characterized in that The weight proportion of the fiber thermal conductive material is 100-200 parts.

14. The preparation method according to claim 1, characterized in that The weight proportion of the other thermally conductive fillers is 300-400 parts.

15. The preparation method according to claim 1, characterized in that The weight portion of the magnetic conductive filler is 200-300 parts.

16. The preparation method according to claim 1, characterized in that The thickness of the blank after the first orientation is 0.1-3 mm.

17. The preparation method according to claim 1, characterized in that The frequency of the physical vibration is 20-100 Hz or 5-30 kHz.

18. The preparation method according to claim 1, characterized in that The intensity of the magnetic field orientation is 0.3-5 T.

19. The preparation method according to claim 1, characterized in that The curing method includes heating curing.

20. The preparation method according to claim 19, characterized in that The temperature of the heating and curing is 85-160°C.

21. The preparation method according to claim 19, characterized in that The heating and curing time is 3-30 min.

22. The preparation method according to claim 1, characterized in that After the solidification, the method further comprises stacking the obtained blanks.

23. The preparation method according to claim 22, characterized in that The stacking method includes bonding.

24. The preparation method according to claim 1, characterized in that The preparation method comprises the following steps: (1) Mixing silicone rubber, fiber thermal conductive material, other thermal conductive fillers and magnetic conductive fillers to form a blank with a viscosity of 2000-100000 mPa·S; (2) orienting the blank obtained in step (1) by rod coating, blade coating or casting, or a combination of at least two of the methods, to form a blank with a thickness of 0.1-3 mm; (3) The blank obtained in step (2) is advanced at a speed of 0.5-1.5 m / min and subjected to physical vibration at a frequency of 20-100 Hz or 5-30 kHz, and is simultaneously subjected to magnetic field orientation at an intensity of 0.3-5 T, the time for physical vibration and magnetic field orientation is controlled to be 5-10 s, and the direction of magnetic field orientation is different from the direction of the blank advancement and the first orientation, thereby completing the second orientation; (4) heating and curing the blank obtained in step (3) at 85-160° C. for 3-30 min to obtain the thermal conductive interface material; or The blank obtained in step (3) is heated and cured at 85-160° C. for 3-30 min, and the heated and cured blanks are stacked to obtain the thermal conductive interface material.

25. A thermally conductive interface material, characterized in that: The thermal interface material is prepared by the preparation method according to any one of claims 1 to 24.

26. An electronic chip, characterized in that: The electronic chip comprises the thermally conductive interface material of claim 25 .

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