Design method to improve thermal performance of composite materials by regulating the type and number of clusters

Abstract

The present invention discloses a design method for improving the thermal performance of composite materials by regulating the type and number of clusters. The composite material designed by this method is composed of an inorganic filler and an organic polymer matrix, wherein the inorganic filler is a high thermal conductivity material in the form of clusters. By regulating the type and number of filler clusters, the orderly construction of the internal heat conduction path of the system is achieved, thereby obtaining a composite thermal interface material with ultra-high thermal conductivity at a low filler volume fraction. The thermal interface material prepared by this method has excellent ductility and is adaptable to a variety of thermal interface applications. At the same time, due to its ultra-high thermal conductivity and low filler volume fraction characteristics, it effectively improves the thermal management efficiency of the device, reduces energy consumption and saves materials, and further improves the performance release and service life of the device.

Description

Technical Field

[0001] The present invention relates to the field of new materials and application technologies, and in particular to a design method for improving the thermal performance of composite materials by regulating the types and numbers of clusters. Background Art

[0002] As electronic components rapidly develop toward miniaturization, high integration, and high performance, the thermal power density per unit area of these devices continues to increase, placing higher demands on the thermal conductivity and adaptability of thermal management materials. Thermal interface materials (TIMs), a key component in heat dissipation systems, are widely used in computer processors (CPUs), mobile phone chips, power devices, new energy vehicles, and other fields. Their primary function is to fill the microscopic gaps between devices and heat dissipation components, reducing interfacial thermal resistance and improving overall heat transfer efficiency.

[0003] Traditional thermal interface materials are typically made by filling an organic polymer matrix with highly thermally conductive inorganic fillers (such as alumina and boron dioxide). However, due to factors such as high interfacial thermal resistance between fillers and discontinuous filler connection paths, even at high filler volume fractions, improvements in the overall thermal conductivity of the material remain limited. Furthermore, high filler loadings can lead to reduced processing performance and flexibility in composite materials, while increasing manufacturing costs and energy consumption, hindering their widespread practical application.

[0004] Existing methods for improving the thermal conductivity of composite materials often focus on optimizing single factors, such as improving filler surface and interface compatibility, manipulating filler size and morphology, and constructing simple filler networks. However, achieving efficient thermal conductivity while maintaining a low filler volume fraction remains difficult. Percolation theory offers a new approach: in random systems, long-range continuity can be achieved through specific connection structures, significantly improving the overall performance of the system.

[0005] In this context, how to systematically regulate the organizational form of inorganic fillers in the organic polymer matrix, accurately design the number of isolated nanowires, the type and number of free filler clusters, and their spatial position and distribution, and effectively construct an orderly, continuous, and efficient heat conduction path, has become the key to realizing the design of low-filling, high-thermal conductivity composite thermal interface materials.

[0006] Currently, research on the mechanisms and coordinated control methods of different morphological cluster structures in improving the thermal performance of composite materials is insufficient, lacking mature systematic design theories and engineering implementation paths. Therefore, a design method for organic-inorganic composite thermal interface materials that can significantly improve thermal conductivity at low filling volume fractions by regulating the type and number of clusters while also taking into account the material's ductility and adaptability is urgently needed to meet the stringent heat dissipation requirements of the next generation of high-performance electronic devices. Summary of the Invention

[0007] In response to the shortcomings of the existing technology, the purpose of the present invention is to provide a design method for improving the thermal performance of composite materials by regulating the type and number of clusters. The high thermal conductivity organic-inorganic composite thermal interface material designed by this method is composed of an inorganic filler and an organic polymer material matrix. By regulating one or more of the material, aspect ratio, type and number of filler clusters of the inorganic filler, an efficient heat conduction path is systematically constructed to achieve ultra-high thermal conductivity performance at a lower filling volume fraction.

[0008] In the present invention, a cluster refers to a connected structural unit formed by several nanowires connected by endpoint or spatial contact in a composite material system. Clusters are classified according to the number of nanowires contained within them. Specifically, a connected structure composed of two nanowires is called a "2-nanowire cluster," a structure composed of three nanowires is called a "3-nanowire cluster," and so on. A cluster composed of n nanowires is called an "n-nanowire cluster." Clusters must meet connectivity requirements, that is, there is a direct or indirect connection path between any two nanowires, and each nanowire belongs to only one cluster. The nanowires within the cluster are randomly connected, ensuring contact or endpoint connection, and the spatial distribution of the clusters presents a random coordinate distribution.

[0009] The technical solution of the present invention is specifically described as follows.

[0010] The present invention provides a design method for an organic-inorganic composite thermal interface material based on regulating the type and number of clusters. The composite material is an organic-inorganic composite thermal interface material, which is composed of an organic polymer material matrix and inorganic filler clusters filled in the matrix. The inorganic filler clusters are high thermal conductivity materials, and the filler clusters present a variety of cluster morphologies. The method comprises the following steps:

[0011] Step 1: Construct inorganic filler systems of different types and structures

[0012] Based on numerical simulation methods, the types and quantities of filler clusters are regulated, and filler clusters with different inorganic filler connection methods are constructed to form inorganic filler systems with different internal microstructures.

[0013] Step 2: Constructing organic-inorganic composite thermal interface materials

[0014] The constructed inorganic filler systems were randomly filled into the organic polymer matrix. The heat transport path was designed based on the control strategy of different cluster types and numbers. The type and number of filler clusters, as well as one or more of the materials and aspect ratios of the inorganic fillers that make up the filler clusters were controlled. The thermal conductivity performance of the entire system was numerically simulated and calculated. When the number of clusters in the system was 2 to 4, the thermal conductivity met the thermal conductivity range of 5 to 9 W·m -1 ·K -1When the type and number of clusters are controlled, the design of organic-inorganic composite thermal interface materials with low filling volume fraction and high thermal conductivity is completed.

[0015] In the present invention, in step 1, the inorganic filler selected to form the filler cluster has a rod-like morphology, a length designed to be in the range of 0.5 to 5 microns, and a diameter designed to be in the range of 1 to 100 nanometers.

[0016] In the present invention, in step 1, the number of types of filler clusters is designed to be in the range of 2 to 10, and the size of the filler clusters does not exceed a filler combination of 10 nanowires.

[0017] In the present invention, in step 1, the filler clusters composed of nanowires are randomly combined.

[0018] In the present invention, in step 1, the material of the inorganic filler is one of silver Ag, gold Au, copper Cu, aluminum Al, silicon dioxide SiO2, aluminum oxide Al2O3, zinc oxide ZnO, magnesium oxide MgO, titanium oxide TiO2, aluminum nitride AlN, boron nitride BN, silicon carbide SiC, and boron carbide B4C.

[0019] In the present invention, in step 2, the organic polymer material matrix is selected from one of epoxy resin, silicone rubber, polyurethane, polyimide, polyethylene, polypropylene, polymethyl methacrylate, polystyrene, polyester, polyamide, polyetheretherketone or polytetrafluoroethylene.

[0020] In the present invention, in step 2, the total volume fraction of the inorganic filler clusters filled into the organic polymer material matrix is 20% to 50%.

[0021] In the present invention, in step 2, numerical simulation can be used to calculate the percolation threshold when the filler clusters form a thermal percolation network (i.e., the volume fraction of the inorganic filler clusters when percolation occurs). The specific method includes:

[0022] The system was first dimensionlessly normalized to a 1×1×1 cube. A rod-shaped metal material was selected as an inorganic filler, and filler clusters of varying morphologies were constructed. By manipulating the inorganic filler's aspect ratio (setting its length and diameter), the type and number of filler clusters within the system were controlled. Using Monte Carlo simulation, the constructed clusters of varying types were randomly populated within the simulated cube. Periodic boundary conditions were implemented to address complex boundary conditions. Clusters that extended in the X direction were truncated, and clusters that extended in the Y and Z directions were truncated and periodically translated into the simulated cube. The type and number of clusters within the system were then calculated at each moment.

[0023] In the present invention, step two establishes an equivalent thermal resistance network model based on the basic physical properties of the inorganic filler and the organic polymer matrix, including the thermal conductivity and thermal resistance of the inorganic filler, the interfacial thermal resistance between fillers, the interfacial thermal resistance between fillers and the matrix, and the thermal conductivity of the organic matrix itself. Using a thermal resistance network algorithm, combined with the heat flow law rewritten from Kirchhoff's current law, a conjugate gradient algorithm is used for self-consistent solution, ultimately determining the thermal conductivity of the overall composite material. The types and number of clusters within the system are then calculated and verified.

[0024] According to the method proposed in the present invention, any one or several process routes can be combined to randomly disperse clusters of different types and numbers into an organic polymer matrix to prepare an organic-inorganic composite thermal interface material with controllable structure and excellent performance.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention proposes for the first time to achieve the orderly construction of internal heat flow channels of organic-inorganic composite thermal interface materials by regulating the types and numbers of filler clusters. In the system, one or more of the material, aspect ratio, type and number of filler clusters of inorganic fillers are regulated to effectively optimize the design of heat conduction paths, so that thermal interface materials with higher thermal conductivity can be achieved at lower volume fractions of inorganic filler clusters. By combining numerical simulation with percolation theory, the effects of different types and numbers of clusters on the overall thermal properties are analyzed, thereby achieving the regulation of the thermal properties of the composite material. The organic-inorganic composite thermal interface material designed by the present invention is composed of inorganic high thermal conductivity filler clusters and an organic polymer matrix. It has excellent thermal conductivity and good mechanical flexibility and can be adapted to a variety of complex thermal interface application scenarios. In particular, by optimizing the cluster structure and the layout of the heat flow channels inside the system, the present invention can obtain efficient thermal conductivity performance under conditions of inorganic filler volume fractions lower than those required by traditional designs, significantly reducing material costs and preparation difficulty, and providing a new solution for the application of high-performance thermal interface materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the internal filler of the composite material system for regulating the type and number of clusters of the present invention.

[0028] Figure 2 It is a schematic diagram of the design process of the present invention.

[0029] Figure 3 This is a graph showing the volume fraction of filler clusters and the types and numbers of filler clusters in the organic-inorganic composite thermal interface material designed based on the method of the present invention in Example 1.

[0030] Figure 4This is a graph showing the number of cluster types and thermal conductivity of the composite material designed based on the method of the present invention in Example 1. DETAILED DESCRIPTION

[0031] The present invention will be further described below.

[0032] like Figure 1 、 Figure 2 As shown, the specific steps of the present invention are as follows: A method for designing thermal properties of an organic-inorganic composite thermal interface material based on regulating the type and number of filler clusters comprises the following steps:

[0033] Step 1: construct filler cluster types and numbers with different numbers of nanowire combinations;

[0034] Step 2: Randomly fill the organic polymer matrix with filler clusters of varying types and quantities to design the heat transport pathways for the organic-inorganic composite thermal interface material. Numerical calculations are performed to determine the thermal conductivity of the organic-inorganic composite thermal interface material, completing the design and fabricating the material using appropriate methods and processes.

[0035] Furthermore, the material of the inorganic filler in step 1 can be designed to be an electrically insulating material, such as silver (Ag), gold (Au), copper (Cu), aluminum (Al), silicon dioxide (SiO2), aluminum oxide (Al2O3), zinc oxide (ZnO), magnesium oxide (MgO), titanium oxide (TiO2), aluminum nitride (AlN), boron nitride (BN), silicon carbide (SiC), boron carbide (B4C) and other materials with good thermal conductivity.

[0036] Furthermore, in the step 1, the shape of the inorganic filler is designed to be rod-shaped, preferably a rod-shaped structure with an aspect ratio of 10.

[0037] Furthermore, in the step 1, the length of the inorganic filler is designed to be in the range of 0.5 to 5 microns, and the diameter is designed to be in the range of 1 to 100 nanometers.

[0038] Furthermore, in step 1, the number of types of filler clusters is designed to be in the range of 2 to 10, and the size of the filler clusters does not exceed a filler combination of 10 nanowires.

[0039] Furthermore, in the step 1, the filler clusters composed of nanowires are randomly combined.

[0040] Furthermore, in step 2, the organic polymer material matrix is an organic polymer elastic material with good elasticity and flexibility and electrical insulation, such as epoxy resin, silicone rubber, polyurethane, polyimide, polyethylene, polypropylene, polymethyl methacrylate, polystyrene, polyester, polyamide, polyetheretherketone, polytetrafluoroethylene, etc.

[0041] Furthermore, in the step 2, the volume fraction of the inorganic filler filled into the organic polymer material matrix is 20% to 50%.

[0042] Furthermore, in the step 2, a process or manufacturing method is selected to mix the isolated nanowires, filler clusters and the polymer matrix.

[0043] Example 1

[0044] like Figure 3 As shown, the organic-inorganic composite thermal interface material designed by the present invention by regulating the type and number of clusters selects silver nanowires (Ag) with high thermal conductivity as inorganic filler, polyvinylidene fluoride (PVDF) as organic polymer substrate, and designs and regulates the type and number of clusters to construct a thermal interface composite material. Specifically, 9 different types of nanowire clusters with nanowire connection numbers ranging from 2 to 10 are designed, and different types of clusters are randomly doped into the PVDF substrate in a ratio of 40:20:10:2:3:2:3:2:2. As the filler clusters are gradually filled, connections between clusters of the same type and connections between clusters of different types appear in the system, generating new clusters, which in turn causes the type of clusters to change. When the type of cluster k in the system increases, the number of clusters increases, and the number of clusters increases. Ag When the peak number of cluster types k in the system is 16, most clusters of the same or different types in the system are in a separated state, with only a small number of clusters connected. Continue to increase the number of clusters until the number of cluster types k in the system is Ag = When the peak number of cluster types that can exist in the system is k=16, clusters begin to connect significantly, forming a preliminary conductive heat transfer path. At this time, the number of cluster types in the system is the largest. When the number of clusters increases further, the number of cluster types in the system is k. Ag When it drops rapidly and finally stabilizes at 2~4, most of the clusters in the system are connected together to form an infinitely large conductive filler network that runs through the left and right boundaries. If the number of clusters continues to increase, the types of clusters will also tend to be stable.

[0045] The present invention designs an organic-inorganic composite thermal interface material by regulating the type and number of clusters, and selects a thermal conductivity of 0.19Wm -1 K -1 Polyvinylidene fluoride (PVDF) is used as the organic polymer matrix, and the thermal conductivity is selected to be 429Wm -1 K -1The interfacial thermal resistance between Ag nanowires is calculated by weighted average using rod-shaped Ag nanowires as fillers, R Ag-Ag The interface thermal resistance is 210 -10 m 2 KW -1 , using numerical simulation calculations in programming software, first dimensionless the system, set the system side length to 1, select the system ratio as l / L=0.2, l=2μm (nanowire length), aspect ratio l / d=10, by regulating the type and number of filler clusters, rod-shaped Ag nanowires with a length of 2μm and a diameter of 0.02μm are randomly dispersed in a unit cube with a side length of 1, Monte Carlo simulation is used in three-dimensional space, using a soft core model, setting the type and number of filler clusters, and processing through boundary conditions, That is, the nanowires that exceed the area along the x-direction are cut off, and the nanowires in the y- and z-directions are cut and periodically translated into the cube. Through numerical model calculations, the percolation threshold of the filler clusters inside the system can be calculated. Then, the basic material properties (thermal conductivity, thermal resistance) and the interface thermal resistance between fillers and the thermal conductivity of the matrix itself are given. The heat flow law rewritten by the thermal resistance network algorithm and Kirchhoff's current law is used to obtain the heat flow. The conjugate gradient algorithm is used for self-consistent solution to solve the effective thermal conductivity of the system. Figure 4 , designed 9 different cluster types with 2-10 nanowire connections, and the number of different types of clusters was filled in a ratio of 40:20:10:2:3:2:3:2:2. When the number of cluster types in the system stabilized at 2-4, a composite thermal interface material with excellent thermal performance was successfully designed. At this time, the volume fraction of the filler clusters in the system was reduced by about 10%-25% compared with the volume fraction of a single filler, and the thermal conductivity was as high as 9.8Wm -1 K -1 .

[0046] The method described above optimizes the internal heat flow path structure by regulating the type and number of filler clusters, thereby achieving ultra-high thermal conductivity improvements in organic-inorganic composite thermal interface materials at relatively low filler volume fractions. The designed thermal interface material, composed of inorganic fillers (including isolated nanowires, free clusters, and percolation networks) and an organic polymer matrix, exhibits excellent flexibility and ductility, adapting to more complex thermal interface environments. This reduces energy consumption and material consumption, while further enhancing device performance and lifespan.

Claims

1. A design method for improving the thermal performance of composite materials by regulating the type and number of clusters, characterized in that: The composite material is an organic-inorganic composite thermal interface material, which is composed of an organic polymer material matrix and inorganic filler clusters filled in the matrix. The inorganic filler clusters are high thermal conductivity materials and the filler clusters present various cluster morphologies. The composite material comprises the following steps: Step 1: Construct inorganic filler systems of different types and structures Based on numerical simulation methods, the types and quantities of filler clusters are regulated, and filler clusters with different inorganic filler connection methods are constructed to form inorganic filler systems with different internal microstructures. Step 2: Constructing organic-inorganic composite thermal interface materials The constructed inorganic filler systems were randomly filled into the organic polymer matrix. The heat transport path was designed based on the control strategy of different cluster types and numbers. The type and number of filler clusters, as well as one or more of the materials and aspect ratios of the inorganic fillers that make up the filler clusters were controlled. The thermal conductivity performance of the entire system was numerically simulated and calculated. When the number of clusters in the system was 2 to 4, the thermal conductivity met the thermal conductivity range of 5 to 9 W·m -1 ·K -1 When the type and number of clusters are controlled, the design of organic-inorganic composite thermal interface materials with low filling volume fraction and high thermal conductivity is completed.

2. The design method for improving the thermal performance of composite materials by regulating the type and number of clusters according to claim 1, characterized in that: In step 1, the inorganic filler constituting the filler cluster has a rod-shaped morphology, a length designed to be in the range of 0.5 to 5 microns, and a diameter designed to be in the range of 1 to 100 nanometers.

3. The design method for improving the thermal performance of composite materials by regulating the type and number of clusters according to claim 1, characterized in that: In step 1, the inorganic filler is selected from one of silver Ag, gold Au, copper Cu, aluminum Al, silicon dioxide SiO2, aluminum oxide Al2O3, zinc oxide ZnO, magnesium oxide MgO, titanium oxide TiO2, aluminum nitride AlN, boron nitride BN, silicon carbide SiC, and boron carbide B4C.

4. The design method for improving the thermal performance of composite materials by regulating the type and number of clusters according to claim 1, characterized in that: In step 1, the number of filler clusters is designed to range from 2 to 10, and each filler cluster is composed of 2 to 10 randomly connected nanowires.

5. The design method for improving the thermal performance of composite materials by regulating the type and number of clusters according to claim 1, characterized in that: In step 2, the organic polymer material matrix is selected from one of epoxy resin, silicone rubber, polyurethane, polyimide, polyethylene, polypropylene, polymethyl methacrylate, polystyrene, polyester, polyamide, polyetheretherketone, and polytetrafluoroethylene.

6. The design method for improving the thermal performance of composite materials by regulating the type and number of clusters according to claim 1, characterized in that: In step 2, the total volume fraction of the inorganic filler clusters in the composite material is 20% to 50%.

7. The design method for improving the thermal performance of composite materials by regulating the type and number of clusters according to claim 1, characterized in that: Through numerical simulation, based on the thermal conductivity and thermal resistance of inorganic fillers, the interfacial thermal resistance between filler clusters, the interfacial thermal resistance between inorganic fillers and the matrix, and the thermal conductivity parameters of the matrix itself, the heat flow is solved using the thermal resistance network algorithm and the heat flow law rewritten by Kirchhoff's current law. The conjugate gradient algorithm is combined for a self-consistent solution to obtain the effective thermal conductivity of the system.

Images