A smart phase change thermal pad for SSDs and its preparation method

Abstract

This application provides a smart phase change thermal pad for SSDs and its preparation method, belonging to the field of electronic device heat dissipation. The smart phase change thermal pad includes: an elastic substrate composed of a lower chip contact layer and an upper heat sink contact layer; the lower chip contact layer is composed of hexagonal boron nitride nanosheets filled with silicone rubber, and the upper heat sink contact layer is composed of carbon fiber fragments filled with silicone rubber; phase change microcapsules dispersed in the upper heat sink contact layer, with a core material of a composite of n-tetracosane, n-triane, and zinc oxide nanowires, and a wall material of melamine-formaldehyde resin; and a directional carbon nanotube array vertically embedded in the elastic substrate, penetrating both the lower chip contact layer and the upper heat sink contact layer. In high power density solid-state drives, this application simultaneously solves the problems of rapid instantaneous temperature rise caused by transient thermal shock and continuous efficient heat dissipation under steady-state thermal load, ensuring interface stability and reliability under long-term use.

Description

Technical Field

[0001] This application relates to the field of heat dissipation technology for electronic devices, and in particular to a smart phase change thermal pad for SSDs and its preparation method. Background Technology

[0002] Solid-state drives (SSDs), as core storage devices, are rapidly advancing towards high-speed PCIe 5.0 / 6.0 interfaces and high-density QLC / PLC storage. This is accompanied by a dramatic increase in power density and heat generation. During high-speed read / write operations, the SSD's controller chip and NAND flash memory generate brief power spikes, causing the chip junction temperature to surge transiently within seconds or even milliseconds, resulting in highly destructive "thermal shocks." To address this challenge, the industry commonly uses traditional thermal interface materials such as thermal grease and thermal pads, aiming to establish a heat conduction path by filling the air gap between the chip and the heatsink, thus stably dissipating the generated heat.

[0003] However, these traditional heat dissipation solutions have significant shortcomings. First, they are essentially passive and static heat conductors, their heat dissipation capacity relying on the inherent thermal conductivity of the materials. They can only handle relatively stable and continuous heat loads, offering almost no effective buffering or suppression for the aforementioned transient thermal shocks, causing chip temperatures to easily exceed the throttling threshold and resulting in performance fluctuations. Second, their thermal conductivity is limited by the phonon scattering interface formed by the random distribution of filler material, creating an inherent thermal conductivity bottleneck. Furthermore, under long-term thermal cycling stress, traditional materials are prone to aging, cracking, or plastic deformation, leading to increased interfacial contact thermal resistance and decreased reliability. Therefore, current technologies cannot simultaneously solve the problems of rapid instantaneous temperature rise due to transient thermal shocks and continuous efficient heat dissipation under steady-state heat loads in high-power-density SSDs, while ensuring interface stability and reliability over long-term use. This has become a key bottleneck restricting the development of high-performance SSDs. Summary of the Invention

[0004] This application provides a smart phase change thermal pad for SSDs and its preparation method to solve the following technical problem: how to simultaneously solve the problem of rapid instantaneous temperature rise caused by transient thermal shock and continuous and efficient heat dissipation of steady-state thermal load in high power density solid-state drives, and ensure interface stability and reliability under long-term use.

[0005] In a first aspect, embodiments of this application provide a smart phase change thermal pad for SSDs, the smart phase change thermal pad comprising: An elastic substrate, comprising a lower chip contact layer and an upper heat sink contact layer, wherein the lower chip contact layer is composed of hexagonal boron nitride nanosheets filled with silicone rubber, and the upper heat sink contact layer is composed of carbon fiber fragments filled with silicone rubber. Phase change microcapsules are dispersed in the upper heat sink contact layer. The core material of the phase change microcapsules is a composite of n-tetracosane, n-triane and zinc oxide nanowires, and the wall material is melamine-formaldehyde resin. A directional carbon nanotube array is vertically embedded in the elastic matrix and penetrates the lower chip contact layer and the upper heat sink contact layer.

[0006] Optionally, the thickness of the intelligent phase change thermal pad is 120–250 μm; The thickness of the lower chip contact layer is 20–50 μm; In the lower chip contact layer, the mass fraction of the hexagonal boron nitride nanosheets is 20-40%. The thickness of the upper heat sink contact layer is 100–200 μm; In the upper heat sink contact layer, the mass fraction of the carbon fiber fragments is 10-25%.

[0007] Optionally, the mass of the phase change microcapsule is 15% to 30% of the total mass of the upper heat sink contact layer; In the phase change microcapsules, the average particle size of the core material is 20–80 μm, and the average thickness of the wall material is 0.5–2 μm; The areal density of the oriented carbon nanotube array is 10–30 mg / cm³. 2 .

[0008] Optionally, the preparation method of the phase change microcapsules includes the following steps: S101. At 60-80℃, n-tetracosane, n-triane and zinc oxide nanowires are mixed and ultrasonically treated to obtain a composite core material. S102. Melamine is added to an aqueous formaldehyde solution and reacted under alkaline conditions at 60-75°C for 30-90 minutes to obtain an aqueous solution of melamine-formaldehyde prepolymer. S103. Under stirring, the composite core material is added to the aqueous solution of the melamine-formaldehyde prepolymer containing emulsifier, and emulsification is performed using a high-speed shear emulsifier to obtain an oil / water emulsion. S104. The oil / water emulsion is heated to 60-75°C, kept at the temperature and stirred continuously for 2-5 hours to allow the melamine-formaldehyde prepolymer to undergo a polymerization reaction at the droplet interface of the composite core material, thereby obtaining a mixture containing microcapsules. S105. The mixture is cooled, filtered, washed and dried to obtain the phase change microcapsule powder.

[0009] Optionally, the mass ratio of n-tetracosane to n-triane is 1:(1-3); The mass of the zinc oxide nanowires is 1-5% of the total mass of the n-tetracosane and the n-triane; The molar ratio of melamine to formaldehyde is 1:(3-4); The mass ratio of the composite core material to the solids in the melamine-formaldehyde prepolymer aqueous solution is (5-10):1. The mass of the emulsifier is 1 to 5% of the mass of the melamine-formaldehyde prepolymer aqueous solution.

[0010] Optionally, the method for preparing the oriented carbon nanotube array includes the following steps: S201. Deposit a thin film of iron catalyst on the growth substrate; S202. The growth substrate with iron catalyst deposited is placed in a chemical vapor deposition reactor, heated to the growth temperature under a protective gas atmosphere, and then ethylene reaction gas is introduced to grow a vertically oriented carbon nanotube array. S203. After the carbon nanotube array is grown, maintain the reactor temperature, stop the introduction of ethylene reaction gas, and introduce methane reaction gas. Use plasma-enhanced chemical vapor deposition to grow a few-layer graphene cap on the top of the carbon nanotube array in situ, and obtain a substrate with a oriented carbon nanotube array.

[0011] Optionally, the thickness of the iron catalyst film is 1–10 nm; The carbon nanotube array is grown at a temperature of 600–800℃ for a time of 10–30 min. The plasma-enhanced chemical vapor deposition method is applied at a temperature of 600–800℃ for a duration of 30–120 seconds.

[0012] Secondly, embodiments of this application provide a method for preparing a smart phase change thermal pad for SSDs as described in any one of the first aspects, the method comprising the following steps: S1. Mix silicone rubber and hexagonal boron nitride nanosheets in a solvent and stir to obtain a uniform lower chip contact layer paste. S2. Mix silicone rubber and carbon fiber fragments in a solvent and stir to obtain the upper heat sink contact layer slurry. S3. The lower chip contact layer paste and the upper heat sink contact layer paste are sequentially coated on the substrate to obtain the first composite wet film. S4. The phase change microcapsules are uniformly dispersed on the surface of the upper heat sink contact layer of the first composite wet film to obtain the second composite wet film. S5. Align the substrate with the oriented carbon nanotube array with the second composite wet film, and transfer the oriented carbon nanotube array from the growth substrate and vertically embed it into the second composite wet film through an imprinting process, so that it penetrates the upper heat sink contact layer and extends into the lower chip contact layer to obtain the third composite wet film. S6. The third composite wet film is pre-cured at 70-80°C for 20-40 minutes, then heated to 120-150°C for 40-80 minutes. After cooling, peeling and punching, the finished smart phase change thermal pad is obtained.

[0013] Optionally, the pressure of the imprinting process is 0.5 to 5 MPa, and the imprinting temperature is 60 to 90°C.

[0014] Optionally, the coating thickness of the wet film of the lower chip contact layer is controlled to be 30-80 μm, and the coating thickness of the wet film of the upper heat sink contact layer is controlled to be 120-250 μm.

[0015] The technical solutions provided in this application have the following advantages compared with the prior art: This application provides a smart phase change thermal pad for SSDs. Through precise structural design and synergistic use of functional components, it achieves a three-in-one solution for transient thermal shock suppression, steady-state efficient heat dissipation, and long-term interface stability in high power density solid-state drives.

[0016] To address the issue of rapid temperature rise caused by transient thermal shock, phase change microcapsules dispersed in the upper heat sink contact layer play a key role: their core material uses a composite system of n-tetracosane and n-triane, which can match the temperature range of different thermal shock intensities. Through the phase change process, they quickly absorb a large amount of latent heat, suppressing the sudden temperature rise from the source; the zinc oxide nanowires added to the core material construct an internal heat-conducting network, further improving the heat absorption response rate and ensuring that the temperature rise can be buffered in time when thermal shock occurs.

[0017] For the continuous and efficient heat dissipation requirements of steady-state heat load, the oriented carbon nanotube array vertically penetrates the double-layer elastic matrix, constructing a direct heat conduction path connecting the chip and the heat sink. With its extremely high axial heat conduction efficiency, it quickly dissipates the heat continuously generated by the chip. At the same time, the uniformly dispersed carbon fiber fragments in the upper heat sink contact layer form a multi-directional heat conduction network, which works in conjunction with the oriented carbon nanotube array to enhance the heat transfer efficiency in the matrix. The hexagonal boron nitride nanosheets in the lower chip contact layer assist in the initial diffusion of heat, laying the foundation for steady-state heat dissipation.

[0018] Regarding long-term interface stability and reliability, the silicone rubber substrate of the elastic matrix possesses excellent flexibility and conformability, consistently adapting to the microstructure of the chip and heat sink, maintaining tight contact, and preventing increased interfacial thermal resistance. The hexagonal boron nitride nanosheets of the lower chip contact layer combine insulation and dispersion stability, preventing electrical short circuits and maintaining the integrity of the thermal conductivity network. The robust melamine-formaldehyde resin wall structure of the phase change microcapsules effectively prevents core material leakage, ensuring the stability of the phase change function during long-term cyclic use. The design of the oriented carbon nanotube array vertically embedded in the matrix forms a firm bond with the two matrix layers, preventing detachment or displacement during long-term use, ensuring the continuity of the thermal conductivity path, and ultimately achieving long-term reliable thermal management of high power density SSDs under complex operating conditions. Attached Figure Description

[0019] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 A schematic diagram illustrating the result of a smart phase change thermal pad for SSDs provided in an embodiment of this application; Figure 2 A schematic flowchart illustrating a method for preparing a smart phase change thermal pad for SSDs, provided in an embodiment of this application. Figure label: 1-Elastic matrix, 11-Lower chip contact layer, 12-Upper heat sink contact layer, 2-Phase change microcapsule, 3-Oriented carbon nanotube array. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] Figure 1 This is a schematic diagram illustrating the result of a smart phase change thermal pad for SSDs provided in an embodiment of this application.

[0024] like Figure 1 As shown in the figure, this application embodiment provides a smart phase change thermal pad for SSDs, the smart phase change thermal pad comprising: An elastic substrate, comprising a lower chip contact layer and an upper heat sink contact layer, wherein the lower chip contact layer is composed of hexagonal boron nitride nanosheets filled with silicone rubber, and the upper heat sink contact layer is composed of carbon fiber fragments filled with silicone rubber. Phase change microcapsules are dispersed in the upper heat sink contact layer. The core material of the phase change microcapsules is a composite of n-tetracosane, n-triane and zinc oxide nanowires, and the wall material is melamine-formaldehyde resin. A directional carbon nanotube array is vertically embedded in the elastic matrix and penetrates the lower chip contact layer and the upper heat sink contact layer.

[0025] The intelligent phase change thermal pad provided in this application is not a simple superposition of single materials, but a system-level solution designed around the core requirements of SSD thermal management. Its core goal is to simultaneously overcome the two major technical challenges of steady-state thermal conductivity and transient thermal shock suppression. Each component performs its own function and exerts precise force, while also deeply linking and synergistically enhancing each other to build a comprehensive and dynamic thermal management system.

[0026] Among the independent functions of each core component, the elastic matrix serves as the structural and safety foundation of the entire thermal pad. It employs a dual-layer gradient design to achieve functional differentiation: the lower chip contact layer uses silicone rubber as a base, filled with hexagonal boron nitride nanosheets. The hexagonal boron nitride, with its excellent insulation properties, constructs a reliable electrical barrier, fundamentally preventing short circuits between the SSD controller chip's precision circuitry and the upper conductive components—a prerequisite for product compatibility with electronic devices. Simultaneously, the elastic properties of silicone rubber can fully fill the microscopic unevenness of the chip surface under low installation pressure, effectively reducing contact thermal resistance. The high in-plane thermal conductivity of the hexagonal boron nitride nanosheets enables initial lateral heat diffusion, laying the foundation for subsequent efficient heat transfer. The upper heatsink contact layer also uses silicone rubber as a carrier, combined with carbon fiber fragments. These carbon fiber fragments form dense, highly thermally conductive pathways in all directions, creating a low-resistance thermal interface facing the metal heatsink casing. This ensures that heat inside the thermal pad can be quickly transferred to the external heatsink, bridging the "last mile" of heat output.

[0027] Phase change microcapsules are the core unit for achieving "intelligent temperature control" in this thermal pad, playing a crucial role as a temperature "buffer" and "heat reservoir." The core material uses a composite system of n-tetracosane and n-triane, modified with zinc oxide nanowires. When the SSD experiences a sudden heavy load causing a temperature surge to the 45°C–60°C range, the paraffin-based core material rapidly melts and absorbs a large amount of latent heat, acting like a highly efficient "thermal capacitor" to suppress temperature spikes within the sigma-level or even millisievert range. This provides a buffer time for the chip to avoid throttling thresholds, which is the core innovation of the solution. The two-stage phase change platform formed by n-tetracosane (approximately 45°C) and n-triane (approximately 58°C) can achieve "step-like" heat absorption in response to thermal shocks of varying intensities. The zinc oxide nanowires dispersed in the core material construct an internal thermally conductive network, completely solving the inherent defect of slow thermal conductivity in traditional phase change materials and significantly improving the response efficiency of heat absorption and release. The outer melamine-formaldehyde resin wall material plays a crucial role in encapsulation and protection, effectively preventing leakage and contamination of surrounding electronic components after the core material melts, and ensuring the stability of the material for long-term cyclic use.

[0028] Oriented carbon nanotube arrays can be described as a "highway network" for heat flow. Their design, which is vertically embedded in an elastic matrix and runs through a double-layer structure, gives thermal pads exceptional thermal conductivity. The vertically oriented carbon nanotubes themselves have extremely high axial thermal conductivity, providing the shortest and fastest vertical conduction path for heat from the chip surface to the heat sink. The heat transfer efficiency is far superior to that of isotropic random fillers, making it the core channel for steady-state heat dissipation. More importantly, the few-layer graphene cap grown in situ on top of the carbon nanotube array "bridges" adjacent carbon nanotubes in the horizontal direction, forming a three-dimensional interconnected thermal network. When local hot spots appear on the chip, heat can be quickly dispersed to the entire thermal pad area through this horizontal network, with more carbon nanotubes sharing the heat transfer task. This avoids local thermal saturation and achieves "thermal balance" at the system level. This design further expands the thermal management dimensions of thermal pads.

[0029] The synergistic effect of each component is mainly reflected in two dimensions: spatial function and temporal response. In terms of spatial and functional synergy, the three components construct a multi-dimensional, seamless thermal management path. Vertically, a steady-state heat dissipation trunk line is formed, consisting of "chip → lower substrate → oriented carbon nanotube array → upper substrate → heat sink," ensuring efficient heat dissipation under normal operating conditions. Horizontally, hexagonal boron nitride nanosheets in the lower substrate achieve initial heat diffusion at the chip level, while the graphene network on top of the carbon nanotubes completes system-level heat flow redistribution, with the two complementing each other. Meanwhile, the phase change microcapsules dispersed in the upper substrate act as "distributed energy storage units," uniformly covering the heat conduction path and responding to temperature spikes at any time, allowing heat to be efficiently regulated in multiple dimensions, including "points (chip hotspots), lines (carbon nanotubes), surfaces (substrate and graphene network), and volumes (the entire thermal pad)." In terms of dynamic response coordination, the thermal pad can intelligently switch working modes according to the SSD's workload: when the SSD is under low / medium power load, the generated steady-state heat flow is mainly quickly discharged through the vertical heat conduction path of the directional carbon nanotube array to maintain temperature stability; when encountering transient thermal shock caused by instantaneous heavy load, the phase change microcapsules are immediately activated, absorbing a large amount of latent heat through core material melting, quickly "freezing" the temperature rise trend. After the peak of the thermal shock, the stored heat is continuously discharged through the carbon nanotube array, forming a closed-loop response of "buffering-discharge" to ensure that the chip temperature is always controlled within a safe range.

[0030] In summary, this intelligent phase change thermal pad, through the functional differentiation and deep synergy of its components, upgrades from a passive heat-conducting component to an "on-chip thermal management subsystem" capable of sensing the SSD's operating status in real time and dynamically adjusting thermal management strategies. This not only significantly improves the peak operating performance of the SSD but also effectively extends the chip's lifespan through precise temperature control, providing an innovative and practical solution to the heat dissipation bottleneck of high-performance computing devices.

[0031] More importantly, the composite structure of "double-layer elastic matrix + phase change microcapsule + directional carbon nanotube array" designed in this application is fundamentally designed to build an integrated system of "safety assurance - efficient thermal conduction - intelligent temperature control" that meets the thermal management requirements of SSDs. Through functional differentiation and deep synergy, the various structural components precisely address the three core issues in SSD heat dissipation: interface adaptation, thermal resistance reduction, and transient thermal shock suppression. The specific functions are as follows: (1) Double-layer elastic matrix: the basis for structural support and gradient heat conduction The elastic substrate employs a dual-layer gradient design of "lower chip contact layer + upper heatsink contact layer," which balances SSD installation compatibility with targeted thermal conductivity. The lower layer uses silicone rubber as a base, filled with hexagonal boron nitride nanosheets. The high elasticity of the silicone rubber can fully fill the microscopic unevenness on the chip surface, significantly reducing the contact thermal resistance between the chip and the thermal pad, ensuring efficient heat transfer. The hexagonal boron nitride nanosheets combine high in-plane thermal conductivity with excellent insulation, forming both a preliminary thermal network on the chip side and a reliable electrical barrier to prevent short circuits between the chip's delicate circuitry and the upper conductive components (carbon fibers, carbon nanotubes), ensuring the safety of SSD use. The upper layer also uses silicone rubber as a carrier, combined with carbon fiber fragments for filling. Carbon fiber has axial thermal conductivity far exceeding that of hexagonal boron nitride, which can form dense multi-channel thermal conductivity in the matrix and build a low-resistance thermal conductivity interface facing the heat sink. This creates a "green channel" for the rapid transfer of heat from the inside of the thermal pad to the external heat sink, forming a gradient function of "chip-side insulation and thermal conductivity - heat sink-side efficient thermal conductivity" with the lower layer, thus optimizing the overall thermal conductivity path.

[0032] (2) Phase change microcapsules: intelligent buffer units for transient thermal shock The design of dispersing phase change microcapsules in the upper heatsink contact layer precisely targets the thermal shock problem during instantaneous heavy loads of SSDs, giving the thermal pad "intelligent temperature control" capabilities. The core material uses a composite system of n-tetracosane and n-triane, whose melting points correspond to the typical thermal shock temperatures of SSDs under low and high loads, forming a two-stage phase change platform that can achieve stepped heat absorption for temperature spikes of varying intensities. The zinc oxide nanowires added to the core material construct an internal thermally conductive network, overcoming the inherent defect of slow thermal conductivity in traditional paraffin-based phase change materials, significantly improving the response efficiency of heat absorption and release, ensuring that heat can be quickly "locked in" during thermal shocks, and preventing the chip temperature from instantly exceeding the throttling threshold. The melamine-formaldehyde resin wall material plays a crucial role in encapsulation and protection, stably confining the phase change core material within the matrix, preventing it from melting and leaking to contaminate internal SSD components, while ensuring the structural integrity of the microcapsules during the fabrication, installation, and long-term use of the thermal pad, maintaining stable phase change temperature control performance.

[0033] (3) Directed carbon nanotube array: the core pathway for efficient heat conduction throughout the entire structure The structure of a vertically embedded carbon nanotube array penetrating a double-layer elastic matrix is ​​the core design for achieving efficient heat dissipation in SSDs. Carbon nanotubes themselves possess extremely high axial thermal conductivity. Their vertically oriented arrangement creates the shortest and most direct "vertical thermal bridge" for heat transfer from the chip surface (lower layer) to the heat sink (upper layer), resulting in thermal conductivity far superior to isotropic random fillers. This completely solves the problems of high interlayer thermal resistance and long heat transfer paths in traditional thermal pads. Simultaneously, the array's penetrating design breaks down the thermal barrier between the lower and upper layers, allowing heat generated by the chip to directly reach the upper heat sink contact layer without secondary transfer through the interlayer interface. This improves steady-state heat dissipation efficiency and promptly removes the latent heat absorbed by the phase-change microcapsules, creating conditions for cyclic temperature control of the microcapsules and forming a closed loop of "heat absorption-extraction."

[0034] (4) Synergistic effect of the overall structure: comprehensive thermal management system The combination of these three components is not a simple superposition, but rather forms an organic whole with complementary functions and coordinated response: the double-layer elastic matrix provides a stable support structure for the phase change microcapsules and carbon nanotube array, while ensuring installation compatibility and usage safety between the thermal pad and the SSD through elastic adaptation and insulation protection; the phase change microcapsules, acting as "transient temperature control units," buffer the thermal shock generated by the chip under instantaneous heavy load, preventing a sudden temperature rise; the directional carbon nanotube array, acting as "steady-state heat conduction core," continuously dissipates the heat generated by the chip during normal operation and the latent heat absorbed by the microcapsules, ensuring temperature stability. This structural design allows the thermal pad to simultaneously possess "passive high-efficiency heat conduction" and "active intelligent temperature control" capabilities, meeting the heat dissipation requirements of the SSD under normal operating conditions while also coping with the thermal shock of instantaneous heavy load, ultimately achieving the core goals of improving the peak performance of the SSD and extending the chip's lifespan.

[0035] In some embodiments, the thickness of the smart phase change thermal pad is 120–250 μm; The thickness of the lower chip contact layer is 20–50 μm; In the lower chip contact layer, the mass fraction of the hexagonal boron nitride nanosheets is 20-40%. The thickness of the upper heat sink contact layer is 100–200 μm; In the upper heat sink contact layer, the mass fraction of the carbon fiber fragments is 10-25%.

[0036] The intelligent phase change thermal pad, with a thickness of 120–250 μm, provides ample space for functional components such as oriented carbon nanotube arrays and phase change microcapsules, while also adapting to the compact installation environment inside SSD devices, ensuring a tight fit with the chip and heat sink.

[0037] The lower chip contact layer, with a thickness of 20–50 μm, precisely matches the microstructure of the chip surface, achieving full contact while controlling the length of the heat conduction path. The hexagonal boron nitride nanosheets, with a mass fraction of 20–40%, construct an efficient in-plane thermal conductivity network while maintaining the elasticity of silicone rubber. This ensures electrical insulation safety between the chip and the upper conductive components, and also enables the initial lateral diffusion of heat from the chip surface.

[0038] The 100-200μm thickness of the upper heat sink contact layer provides space for the uniform dispersion of phase change microcapsules and the construction of thermal conductivity pathways for carbon fiber fragments. The 10-25% mass fraction of carbon fiber fragments, through proper filling, forms a dense, highly thermally conductive network without compromising the flexibility of the matrix. This effectively reduces the contact thermal resistance between the thermal pad and the heat sink, laying a solid foundation for the efficient transfer of heat to the external heat sink.

[0039] In some embodiments, the mass of the phase change microcapsule is 15% to 30% of the total mass of the upper heat sink contact layer; In the phase change microcapsules, the average particle size of the core material is 20–80 μm, and the average thickness of the wall material is 0.5–2 μm; The areal density of the oriented carbon nanotube array is 10–30 mg / cm³. 2 .

[0040] The phase change microcapsules, comprising 15-30% of the total mass of the upper heatsink contact layer, ensure sufficient phase change energy storage units to efficiently absorb heat generated by transient thermal shocks in SSDs, precisely matching thermal load requirements. This proportion balances temperature control and substrate performance, preserving the high thermal conductivity network constructed from silicone rubber and carbon fiber fragments while allowing for uniform microcapsule dispersion, maintaining the elasticity and adhesion of the thermal pad. It also facilitates seamless integration of heat absorption and conduction with the oriented carbon nanotube array. The core material's average particle size of 20-80 μm ensures uniform distribution of microcapsules within the elastic matrix, while the wall thickness of 0.5-2 μm minimizes the obstruction of latent heat transfer due to phase change while maintaining encapsulation strength.

[0041] 10–30 mg / cm of oriented carbon nanotube arrays 2 The areal density design can ensure the density of the array heat conduction channels while avoiding the agglomeration of carbon nanotubes, providing structural support for efficient vertical heat conduction and uniform lateral diffusion.

[0042] In some embodiments, the method for preparing the phase change microcapsules includes the following steps: S101. At 60-80℃, n-tetracosane, n-triane and zinc oxide nanowires are mixed and ultrasonically treated to obtain a composite core material. S102. Melamine is added to an aqueous formaldehyde solution and reacted under alkaline conditions at 60-75°C for 30-90 minutes to obtain an aqueous solution of melamine-formaldehyde prepolymer. S103. Under stirring, the composite core material is added to the aqueous solution of the melamine-formaldehyde prepolymer containing emulsifier, and emulsification is performed using a high-speed shear emulsifier to obtain an oil / water emulsion. S104. The oil / water emulsion is heated to 60-75°C, kept at the temperature and stirred continuously for 2-5 hours to allow the melamine-formaldehyde prepolymer to undergo a polymerization reaction at the droplet interface of the composite core material, thereby obtaining a mixture containing microcapsules. S105. The mixture is cooled, filtered, washed and dried to obtain the phase change microcapsule powder.

[0043] In some embodiments, the mass ratio of n-tetracosane to n-triane is 1:(1-3); The mass of the zinc oxide nanowires is 1-5% of the total mass of the n-tetracosane and the n-triane; The molar ratio of melamine to formaldehyde is 1:(3-4); The mass ratio of the composite core material to the solids in the melamine-formaldehyde prepolymer aqueous solution is (5-10):1. The mass of the emulsifier is 1 to 5% of the mass of the melamine-formaldehyde prepolymer aqueous solution.

[0044] In step S101, the mixing temperature of 60–80°C allows n-tetracosane and n-triane to fully melt, ensuring uniform mixing of the two phase change materials. Ultrasonic treatment helps zinc oxide nanowires form a uniformly dispersed thermally conductive network within the molten alkanes. The 1:(1–3) mass ratio of n-tetracosane to n-triane precisely controls the phase change temperature range of the composite core material, perfectly covering the typical thermal shock temperature range during SSD operation. The 1–5% mass percentage of zinc oxide nanowires significantly improves the thermal conductivity of the core material, solving the problem of slow thermal conductivity in traditional paraffin-based phase change materials.

[0045] In step S102, alkaline conditions provide a suitable environment for the reaction of melamine and formaldehyde, a reaction temperature of 60-75°C and a reaction time of 30-90 min ensure that the two react fully, and a molar ratio of 1:(3-4) gives the prepolymer suitable reactivity, ultimately forming a melamine-formaldehyde prepolymer aqueous solution with a stable structure that can be subsequently crosslinked.

[0046] In step S103, the synergistic effect of stirring and high-speed shear emulsification can disperse the composite core material into droplets of uniform size; the emulsifier with a mass ratio of 1 to 5% can effectively reduce the interfacial tension between oil and water, maintain the stable state of the oil / water emulsion, and create the preconditions for the uniform coating of each core material droplet.

[0047] In step S104, the insulation temperature of 60–75°C is kept consistent with the prepolymer preparation temperature to avoid temperature fluctuations affecting the coating effect; continuous stirring for 2–5 hours ensures that the melamine-formaldehyde prepolymer is fully cross-linked and polymerized at the core material droplet interface, forming a dense wall material structure. The mass ratio of the composite core material to the solid matter in the prepolymer aqueous solution (5–10:1) can precisely control the wall material thickness, maximizing the retention of the latent heat of phase change of the core material while ensuring the reliability of the core material encapsulation.

[0048] The cooling, filtering, washing and drying process in step S105 is mainly used to remove unreacted raw materials, emulsifiers and other impurities to obtain phase change microcapsule powder with high purity and good dispersibility.

[0049] In some embodiments, the method for fabricating the oriented carbon nanotube array includes the following steps: S201. Deposit a thin film of iron catalyst on the growth substrate; S202. The growth substrate with iron catalyst deposited is placed in a chemical vapor deposition reactor, heated to the growth temperature under a protective gas atmosphere, and then ethylene reaction gas is introduced to grow a vertically oriented carbon nanotube array. S203. After the carbon nanotube array is grown, maintain the reactor temperature, stop the introduction of ethylene reaction gas, and introduce methane reaction gas. Use plasma-enhanced chemical vapor deposition to grow a few-layer graphene cap on the top of the carbon nanotube array in situ, and obtain a substrate with a oriented carbon nanotube array.

[0050] In some embodiments, the thickness of the iron catalyst film is 1–10 nm; The carbon nanotube array is grown at a temperature of 600–800℃ for a time of 10–30 min. The plasma-enhanced chemical vapor deposition method is applied at a temperature of 600–800℃ for a duration of 30–120 seconds.

[0051] In step S201, the iron catalyst film thickness of 1-10 nm can form uniformly sized nanoscale catalyst particles in subsequent high-temperature treatment, providing stable nucleation sites for the vertical directional growth of carbon nanotubes and laying the foundation for the regularity of the array structure.

[0052] In step S202, the protective gas atmosphere effectively prevents the iron catalyst and growth substrate from being oxidized. A growth temperature of 600–800°C is suitable for the vertical growth of carbon nanotubes, ensuring both high crystallinity and axial structural integrity while maintaining catalyst activity. A growth time of 10–30 minutes allows for precise control of the carbon nanotube array height, matching its overall thickness with the intelligent phase-change thermal pad and ensuring penetration through the double-layer elastic matrix. Ethylene, as a reactive gas, provides a sufficient and appropriately active carbon source for carbon nanotube growth, ensuring the array's areal density and structural stability.

[0053] In step S203, maintaining a reaction temperature of 600–800°C avoids damage to the carbon nanotube structure caused by temperature changes. Methane, as the carbon source, enables in-situ growth of few-layer graphene at the top of the carbon nanotubes under plasma-enhanced chemical vapor deposition. The reaction time of 30–120 seconds allows for precise control of the number and size of the graphene caps, achieving horizontal bridging between adjacent carbon nanotubes and constructing a three-dimensional interconnected thermally conductive network.

[0054] Figure 2 This is a schematic flowchart illustrating a method for preparing a smart phase change thermal pad for SSDs, as provided in an embodiment of this application.

[0055] Based on a general inventive concept, such as Figure 2 As shown, this application embodiment provides a method for preparing a smart phase change thermal pad for SSDs as described in any one of the above claims, the method comprising the following steps: S1. Mix silicone rubber and hexagonal boron nitride nanosheets in a solvent and stir to obtain a uniform lower chip contact layer paste. S2. Mix silicone rubber and carbon fiber fragments in a solvent and stir to obtain the upper heat sink contact layer slurry. S3. The lower chip contact layer paste and the upper heat sink contact layer paste are sequentially coated on the substrate to obtain the first composite wet film. S4. The phase change microcapsules are uniformly dispersed on the surface of the upper heat sink contact layer of the first composite wet film to obtain the second composite wet film. S5. Align the substrate with the oriented carbon nanotube array with the second composite wet film, and transfer the oriented carbon nanotube array from the growth substrate and vertically embed it into the second composite wet film through an imprinting process, so that it penetrates the upper heat sink contact layer and extends into the lower chip contact layer to obtain the third composite wet film. S6. The third composite wet film is pre-cured at 70-80°C for 20-40 minutes, then heated to 120-150°C for 40-80 minutes. After cooling, peeling and punching, the finished smart phase change thermal pad is obtained.

[0056] In some embodiments, the pressure of the imprinting process is 0.5 to 5 MPa, and the imprinting temperature is 60 to 90°C.

[0057] In some embodiments, the coating thickness of the wet film of the lower chip contact layer is controlled to be 30-80 μm, and the coating thickness of the wet film of the upper heat sink contact layer is controlled to be 120-250 μm.

[0058] It should be noted that the core of step S1 is to create a uniform and stable lower functional slurry, laying a solid foundation for the insulation and thermal conductivity of the chip contact layer. In this process, silicone rubber and hexagonal boron nitride (h-BN) nanosheets are mixed in a solvent. The solvent effectively reduces the viscosity of the silicone rubber, creating favorable conditions for the uniform dispersion of the h-BN nanosheets. Through stirring, the agglomeration of the h-BN nanosheets is broken up by mechanical force, allowing them to be uniformly distributed within the silicone rubber matrix, forming a continuous in-plane thermally conductive network. This process ensures that the slurry has good coating fluidity and that the subsequently cured lower contact layer possesses both the elasticity of silicone rubber and the high insulation and high thermal conductivity of h-BN, precisely meeting the functional requirements of the chip contact layer.

[0059] Steps S2 and S1 complement each other, focusing on the construction of the upper-layer high thermal conductivity pathways. Silicone rubber and carbon fiber fragments are mixed in a solvent, which also plays a role in adjusting viscosity and aiding in the dispersion of the carbon fiber fragments. Through stirring, the carbon fiber fragments are uniformly dispersed in the silicone rubber, and the excellent thermal conductivity of carbon fiber forms multidirectional thermal conduction pathways within the matrix. The preparation of this slurry aims to balance the elasticity and thermal conductivity of the matrix, ensuring that the subsequently formed upper contact layer can both tightly adhere to the heat sink and rapidly transfer heat, providing reliable structural support for overall steady-state heat dissipation.

[0060] Step S3 is a crucial step in realizing the dual-layer gradient structure. By sequentially coating the lower and upper layers of slurry, the boundaries between the two layers are clearly defined, and their functions do not interfere with each other, avoiding performance failure due to component mixing. The coating thickness of the lower chip contact layer wet film is controlled at 30–80 μm, and that of the upper layer is 120–250 μm. This parameter design fully considers solvent evaporation and substrate shrinkage during subsequent curing. The wet film thickness is slightly larger than the designed thickness of the finished product, which ensures that the target thickness is accurately achieved after curing, while also reserving sufficient space for subsequent imprinting and embedding of carbon nanotube arrays, ensuring thickness matching and overall integrity of the two-layer structure.

[0061] The core of step S4 is to achieve uniform distribution of the phase change temperature control function. Evenly dispersing the phase change microcapsules on the surface of the upper heatsink contact layer allows the microcapsules to be stably embedded in the upper matrix during subsequent curing, effectively preventing aggregation. This uniformly dispersed design ensures that when the SSD experiences thermal shock, regardless of the source of the heat, the corresponding phase change microcapsules respond quickly and absorb latent heat, achieving uniform temperature control across the entire area. Simultaneously, it allows the microcapsules to fully contact the carbon fiber thermally conductive network in the upper layer, creating favorable conditions for the smooth dissipation of absorbed heat.

[0062] Step S5 is crucial for establishing the core thermal conductivity pathway, directly determining the vertical thermal conductivity efficiency of the thermal pad. During operation, the substrate with the grown oriented carbon nanotube (CNT) array is precisely aligned with the second composite wet film to ensure vertical embedding of the CNT array, preventing interruption of the thermal conductivity path due to tilting or misalignment. Then, through an imprinting process, the CNT array is mechanically transferred from the growth substrate to the composite wet film, penetrating the upper layer and extending to the lower layer, constructing a "vertical thermal bridge" connecting the chip and the heat sink. The imprinting pressure is set to 0.5–5 MPa, ensuring smooth embedding of the CNT array into the wet film without breakage, while also allowing for tight adhesion between the CNTs and the substrate components, reducing interfacial thermal resistance. The imprinting temperature is controlled at 60–90°C, which moderately softens the silicone rubber substrate, reducing mechanical resistance during CNT embedding, while avoiding excessive temperature affecting the encapsulation structure of the phase change microcapsules, thus balancing transfer efficiency and component stability.

[0063] Step S6 involves two-step curing and post-treatment to ultimately form a stable finished thermal pad. First, pre-curing at 70–80℃ for 20–40 minutes primarily serves to slowly evaporate the solvent in the slurry, preventing rapid heating that could lead to bubble formation or pores. Simultaneously, it allows the silicone rubber to undergo initial cross-linking, fixing the relative positions of the bilayer structure, phase change microcapsules, and CNT array, preventing deformation and delamination during subsequent high-temperature curing. Then, curing is performed at 120–150℃ for 40–80 minutes. This temperature and time parameter ensures complete cross-linking and curing of the silicone rubber, forming a high-mechanical-strength, elastically stable matrix. This ensures the thermal pad is not easily damaged or deformed during installation and use, while also maintaining the interfacial bonding between the functional components and the matrix, extending its service life. It is worth noting that the decomposition temperature of the melamine-formaldehyde resin used as the microcapsule wall material is above 225℃, while the highest temperature of the two-step curing is 150℃, far below its thermal decomposition threshold. Furthermore, even if the core material partially liquefies, the rigid structure of the wall material prevents leakage and does not damage the microcapsule structure. Finally, after cooling, peeling, and punching, the cured thermal pad structure is stabilized and shaped, and then precisely cut according to the actual installation dimensions of the SSD to ensure that the finished product can be directly adapted to the equipment and meet the needs of engineering applications.

[0064] In summary, the core advantage of this application lies in its integrated thermal management solution that combines structure, function, and adaptation, overcoming the limitations of traditional thermal pads that only provide single-function heat dissipation. Its structural design is highly innovative; the dual-layer gradient elastic matrix achieves precise functional differentiation, ensuring both electrical safety and interface adhesion on the chip contact side while enhancing thermal conductivity on the heatsink contact side. The synergistic design of the through-hole directional carbon nanotube array and dispersed phase-change microcapsules allows the thermal pad to simultaneously possess passive, efficient heat conduction and active, intelligent temperature control capabilities. It can smoothly dissipate heat generated during normal operation while precisely buffering thermal shocks caused by instantaneous heavy loads, fundamentally solving the dual pain points of "insufficient steady-state heat dissipation" and "transient thermal runaway" in SSD cooling. Simultaneously, this design fully considers application adaptability. The flexibility of the elastic matrix allows it to adapt to the microscopic morphology of the chip and heatsink. The compact overall structure meets the installation requirements of the limited space inside SSD devices, and the high stability of each component allows it to adapt to environmental changes and mechanical stresses during long-term use, maintaining reliable performance without additional maintenance.

[0065] In terms of application scenarios, this intelligent phase-change thermal pad is widely compatible with various SSD products, including consumer-grade solid-state drives (such as SSDs built into laptops and desktops), industrial-grade SSDs (such as industrial control equipment and server storage modules), and high-speed SSDs in the high-performance computing field (such as SSDs for data centers and artificial intelligence servers). It is especially suitable for scenarios with stringent requirements for heat dissipation efficiency and stability, such as professional workstations with high-frequency read and write operations, server storage systems that operate continuously for long periods, and SSDs in space-constrained portable electronic devices. It can ensure the continuous output of peak performance of the device through efficient heat dissipation, and extend the life of the SSD through intelligent temperature control. At the same time, it meets the core requirements of electrical safety and ease of installation in different scenarios, providing key support for the performance upgrade and application expansion of SSDs.

[0066] The present application is further illustrated below with reference to specific embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards / industry standards / the disclosure herein; if there are no corresponding national standards / industry standards / the disclosure herein, they are performed according to generally accepted international standards, conventional conditions, or conditions recommended by the manufacturer.

[0067] Example 1 This embodiment provides a smart phase change thermal pad for SSDs. The thermal pad has an overall thickness of 200μm and is composed of the following parts: Elastic substrate: The elastic substrate consists of a lower chip contact layer and an upper heat sink contact layer. The lower chip contact layer has a thickness of 30 μm and is composed of hexagonal boron nitride nanosheets filled with silicone rubber at a mass fraction of 30%. The upper heat sink contact layer has a thickness of 170 μm and is composed of carbon fiber fragments filled with silicone rubber at a mass fraction of 18%.

[0068] Phase change microcapsules: The phase change microcapsules are uniformly dispersed in the upper heat sink contact layer, accounting for 20% of the total mass of the upper heat sink contact layer. The core material of the phase change microcapsules has an average particle size of 50 μm, and the wall material has an average thickness of 1.2 μm. Its specific composition is as follows: Core material: a composite of n-tetracosane, n-triane, and zinc oxide nanowires. The mass ratio of n-tetracosane to n-triane is 1:2, and the mass of the zinc oxide nanowires is 3% of the total mass of the two paraffins. Wall material: melamine-formaldehyde resin.

[0069] Directed carbon nanotube array: The directed carbon nanotube array is vertically embedded in the elastic matrix and penetrates both the lower chip contact layer and the upper heat sink contact layer. The areal density of the directed carbon nanotube array is 20 mg / cm³. 2 .

[0070] The smart phase change thermal pad in this embodiment is prepared by the following method: (1) Preparation of phase change microcapsules S101. At 70℃, n-tetracosane (CAS No. 646-31-1) and n-triane (CAS No. 638-68-6) in a mass ratio of 1:2 were mixed, and zinc oxide nanowires (4-5μm, CAS No. 1314-13-2) accounting for 3% of the total mass of the two were added. The mixture was then ultrasonically treated at 500W power for 60min to obtain a uniform composite core material.

[0071] S102. Melamine is dissolved in formaldehyde-deionized water (methanol oxidation method, concentration 37wt%), the molar ratio of melamine (CAS No. 108-78-1) to formaldehyde is 1:3.5, the pH is adjusted to 8.5 with triethanolamine, and the reaction is carried out at 70℃ for 60 min to obtain melamine-formaldehyde prepolymer aqueous solution.

[0072] S103. Under stirring, the composite core material is added to the melamine-formaldehyde prepolymer aqueous solution containing sodium dodecyl sulfate (3% of the mass of the prepolymer aqueous solution, CAS number 151-21-3), and emulsified at 12000 rpm for 10 min using a high-speed shear emulsifier to obtain a stable oil / water emulsion. The mass ratio of the composite core material to the solids in the prepolymer aqueous solution is 8:1.

[0073] S104. The oil / water emulsion is heated to 70°C, kept at this temperature and stirred continuously for 3 hours to allow the melamine-formaldehyde prepolymer to undergo a polymerization reaction at the interface of the composite core material droplets, thereby obtaining a mixture containing microcapsules.

[0074] S105. The mixture is cooled to room temperature, filtered, washed with deionized water, and dried under vacuum at 50°C to obtain the phase change microcapsule powder.

[0075] (2) Fabrication of oriented carbon nanotube arrays S201. A 5nm thick iron catalyst film is deposited on a silicon wafer by magnetron sputtering.

[0076] S202. Place the silicon wafer with iron catalyst deposited in a chemical vapor deposition reactor, heat it to 700°C under argon protection, and then introduce ethylene (concentration of 20% of the total volume of the reaction gas). The reaction is carried out for 20 minutes to obtain a vertically oriented carbon nanotube array.

[0077] S203. After the carbon nanotube array is grown, the reactor temperature is kept at 700°C, the ethylene supply is stopped, and methane is introduced. The carbon nanotube array is grown in situ at 700°C for 60 seconds using plasma-enhanced chemical vapor deposition, resulting in a few-layer graphene cap on top of the carbon nanotube array, thus obtaining a substrate with a oriented carbon nanotube array.

[0078] (3) Integrated fabrication of intelligent phase change thermal pads S1. Mix silicone rubber (CAS No. 63394-02-5) and 30% by mass of hexagonal boron nitride nanosheets (CAS No. 10043-11-5) in xylene solvent and mechanically stir for 2 hours to obtain a uniform lower chip contact layer slurry.

[0079] S2. Mix silicone rubber with 18% by mass of carbon fiber fragments (CAS No. 7440-44-0, 10~30μm) in xylene solvent and mechanically stir for 2h to obtain a uniform upper heat sink contact layer slurry.

[0080] S3. Using a double-layer slit coating machine, the lower chip contact layer paste and the upper heat sink contact layer paste are sequentially coated on the polyimide release film, wherein the thickness of the lower wet film is controlled at 50 μm and the thickness of the upper wet film is controlled at 220 μm, to obtain the first composite wet film.

[0081] S4. The phase change microcapsules obtained in step (1) are uniformly dispersed on the surface of the upper heat sink contact layer of the first composite wet film by screen printing to obtain the second composite wet film.

[0082] S5. Align the substrate with the oriented carbon nanotube array obtained in step (2) with the second composite wet film, and imprint it with an imprinting roller at a pressure of 2MPa and a temperature of 80°C to transfer the oriented carbon nanotube array from the growth substrate and vertically embed it into the second composite wet film, so that it penetrates the upper heat sink contact layer and extends into the lower chip contact layer to obtain the third composite wet film.

[0083] S6. Pre-cur the third composite wet film at 75°C for 30 minutes, then heat it to 135°C and cure it for 60 minutes. After cooling, peel it off from the release film and punch it into the predetermined size to obtain the finished smart phase change thermal pad.

[0084] Example 2 This embodiment provides a smart phase change thermal pad for SSDs. The thermal pad has an overall thickness of 180μm and is composed of the following parts: Elastic substrate: The elastic substrate consists of a lower chip contact layer and an upper heat sink contact layer. The lower chip contact layer has a thickness of 25 μm and is composed of hexagonal boron nitride nanosheets filled with silicone rubber at a mass fraction of 25%. The upper heat sink contact layer has a thickness of 155 μm and is composed of carbon fiber fragments filled with silicone rubber at a mass fraction of 15%.

[0085] Phase change microcapsules: The phase change microcapsules are uniformly dispersed in the upper heat sink contact layer, accounting for 25% of the total mass of the upper heat sink contact layer. The core material of the phase change microcapsules has an average particle size of 40 μm, and the wall material has an average thickness of 1.0 μm. Its specific composition is as follows: Core material: a composite of n-tetracosane, n-triane, and zinc oxide nanowires. The mass ratio of n-tetracosane to n-triane is 1:1.5, and the mass of the zinc oxide nanowires is 2% of the total mass of the two paraffins. Wall material: melamine-formaldehyde resin.

[0086] Oriented carbon nanotube array: The oriented carbon nanotube array is vertically embedded in the elastic matrix and penetrates the lower chip contact layer and the upper heat sink contact layer. The areal density of the oriented carbon nanotube array is 15 mg / cm².

[0087] The smart phase change thermal pad in this embodiment is prepared by the following method: (1) Preparation of phase change microcapsules S101. At 65°C, n-tetracosane and n-triane in a mass ratio of 1:1.5 are mixed, and zinc oxide nanowires accounting for 2% of the total mass of the two are added. The mixture is then ultrasonically treated at 450W for 50 minutes to obtain a uniform composite core material.

[0088] S102. Melamine is dissolved in formaldehyde-deionized water at a molar ratio of 1:3.2. The pH is adjusted to 8.3 with triethanolamine and reacted at 65°C for 50 min to obtain an aqueous solution of melamine-formaldehyde prepolymer.

[0089] S103. Under stirring, the composite core material is added to the melamine-formaldehyde prepolymer aqueous solution containing sodium dodecyl sulfate (2% by mass of the prepolymer aqueous solution), and emulsified at 11000 rpm for 8 minutes using a high-speed shear emulsifier to obtain a stable oil / water emulsion. The mass ratio of the composite core material to the solids in the prepolymer aqueous solution is 7:1.

[0090] S104. The oil / water emulsion is heated to 65°C, kept at this temperature and stirred continuously for 2.5 hours to allow the melamine-formaldehyde prepolymer to undergo a polymerization reaction at the interface of the composite core material droplets, thereby obtaining a mixture containing microcapsules.

[0091] S105. The mixture is cooled to room temperature, filtered, washed with deionized water, and vacuum dried at 48°C to obtain the phase change microcapsule powder.

[0092] (2) Fabrication of oriented carbon nanotube arrays S201. A 3nm thick iron catalyst film is deposited on a silicon wafer by magnetron sputtering.

[0093] S202. Place the silicon wafer with iron catalyst deposited in a chemical vapor deposition reactor, heat it to 650°C under argon protection, and then introduce ethylene (concentration of 18% of the total volume of the reaction gas). The reaction is carried out for 15 minutes to obtain a vertically oriented carbon nanotube array.

[0094] S203. After the carbon nanotube array is grown, the reactor temperature is maintained at 650°C, the ethylene supply is stopped, and methane is introduced. The carbon nanotube array is grown in situ at 650°C for 50 seconds using plasma-enhanced chemical vapor deposition, resulting in a few-layer graphene cap on top of the carbon nanotube array, thus obtaining a substrate with a oriented carbon nanotube array.

[0095] (3) Integrated fabrication of intelligent phase change thermal pads S1. Mix silicone rubber with 25% by mass of hexagonal boron nitride nanosheets in xylene solvent and mechanically stir for 1.5 h to obtain a uniform lower chip contact layer slurry.

[0096] S2. Mix silicone rubber with 15% carbon fiber fragments in xylene solvent and mechanically stir for 1.5 hours to obtain a uniform upper heat sink contact layer slurry.

[0097] S3. Using a double-layer slit coating machine, the lower chip contact layer paste and the upper heat sink contact layer paste are sequentially coated on the polyimide release film, wherein the thickness of the lower wet film is controlled at 40μm and the thickness of the upper wet film is controlled at 200μm, to obtain the first composite wet film.

[0098] S4. The phase change microcapsules obtained in step (1) are uniformly dispersed on the surface of the upper heat sink contact layer of the first composite wet film by screen printing to obtain the second composite wet film.

[0099] S5. Align the substrate with the oriented carbon nanotube array obtained in step (2) with the second composite wet film, and imprint it with an imprinting roller at a pressure of 1.5 MPa and a temperature of 75°C to transfer the oriented carbon nanotube array from the growth substrate and vertically embed it into the second composite wet film, so that it penetrates the upper heat sink contact layer and extends into the lower chip contact layer to obtain the third composite wet film.

[0100] S6. Pre-cur the third composite wet film at 72°C for 25 minutes, then heat it to 128°C and cure it for 55 minutes. After cooling, peel it off from the release film and punch it into the predetermined size to obtain the finished smart phase change thermal pad.

[0101] Example 3 This embodiment provides a smart phase change thermal pad for SSDs. The thermal pad has an overall thickness of 220μm and is composed of the following parts: Elastic substrate: The elastic substrate consists of a lower chip contact layer and an upper heat sink contact layer. The lower chip contact layer has a thickness of 40 μm and is composed of hexagonal boron nitride nanosheets with a mass fraction of 35% filled with silicone rubber. The upper heat sink contact layer has a thickness of 180 μm and is composed of carbon fiber fragments with a mass fraction of 22% filled with silicone rubber.

[0102] Phase change microcapsules: The phase change microcapsules are uniformly dispersed in the upper heat sink contact layer, accounting for 28% of the total mass of the upper heat sink contact layer. The core material of the phase change microcapsules has an average particle size of 60 μm, and the wall material has an average thickness of 1.5 μm. Its specific composition is as follows: Core material: a composite of n-tetracosane, n-triane, and zinc oxide nanowires. The mass ratio of n-tetracosane to n-triane is 1:2.5, and the mass of the zinc oxide nanowires is 4% of the total mass of the two paraffins. Wall material: melamine-formaldehyde resin.

[0103] Oriented carbon nanotube array: The oriented carbon nanotube array is vertically embedded in the elastic matrix and penetrates the lower chip contact layer and the upper heat sink contact layer. The areal density of the oriented carbon nanotube array is 25 mg / cm².

[0104] The smart phase change thermal pad in this embodiment is prepared by the following method: (1) Preparation of phase change microcapsules S101. At 75°C, n-tetracosane and n-triane in a mass ratio of 1:2.5 were mixed, and zinc oxide nanowires accounting for 4% of the total mass of the two were added. The mixture was then ultrasonically treated at 550W for 70 minutes to obtain a uniform composite core material.

[0105] S102. Melamine is dissolved in formaldehyde-deionized water at a molar ratio of 1:3.8. The pH is adjusted to 8.7 with triethanolamine and reacted at 75°C for 75 min to obtain an aqueous solution of melamine-formaldehyde prepolymer.

[0106] S103. Under stirring, the composite core material is added to the melamine-formaldehyde prepolymer aqueous solution containing sodium dodecyl sulfate (4% by mass of the prepolymer aqueous solution), and emulsified at 13000 rpm for 12 min using a high-speed shear emulsifier to obtain a stable oil / water emulsion. The mass ratio of the composite core material to the solids in the prepolymer aqueous solution is 9:1.

[0107] S104. The oil / water emulsion is heated to 75°C, kept at this temperature and stirred continuously for 4 hours to allow the melamine-formaldehyde prepolymer to undergo a polymerization reaction at the interface of the composite core material droplets, thereby obtaining a mixture containing microcapsules.

[0108] S105. The mixture is cooled to room temperature, filtered, washed with deionized water, and vacuum dried at 52°C to obtain the phase change microcapsule powder.

[0109] (2) Fabrication of oriented carbon nanotube arrays S201. An 8nm thick iron catalyst film is deposited on a silicon wafer by magnetron sputtering.

[0110] S202. Place the silicon wafer with iron catalyst deposited in a chemical vapor deposition reactor, heat it to 750°C under argon protection, and then introduce ethylene (concentration of 22% of the total volume of the reaction gas). The reaction is carried out for 25 minutes to obtain a vertically oriented carbon nanotube array.

[0111] S203. After the carbon nanotube array is grown, the reactor temperature is maintained at 750°C, the ethylene supply is stopped, and methane is introduced. The carbon nanotube array is grown in situ at 750°C for 80 seconds using plasma-enhanced chemical vapor deposition, resulting in a few-layer graphene cap on top of the carbon nanotube array, thus obtaining a substrate with a oriented carbon nanotube array.

[0112] (3) Integrated fabrication of intelligent phase change thermal pads S1. Mix silicone rubber with 35% by mass of hexagonal boron nitride nanosheets in xylene solvent and mechanically stir for 2.5 h to obtain a uniform lower chip contact layer slurry.

[0113] S2. Mix silicone rubber with 22% carbon fiber fragments in xylene solvent and mechanically stir for 2.5 hours to obtain a uniform upper heat sink contact layer slurry.

[0114] S3. Using a double-layer slit coating machine, the lower chip contact layer paste and the upper heat sink contact layer paste are sequentially coated on the polyimide release film, wherein the thickness of the lower wet film is controlled at 60μm and the thickness of the upper wet film is controlled at 235μm, to obtain the first composite wet film.

[0115] S4. The phase change microcapsules obtained in step (1) are uniformly dispersed on the surface of the upper heat sink contact layer of the first composite wet film by screen printing to obtain the second composite wet film.

[0116] S5. Align the substrate with the oriented carbon nanotube array obtained in step (2) with the second composite wet film, and imprint it with an imprinting roller at a pressure of 3MPa and a temperature of 85°C to transfer the oriented carbon nanotube array from the growth substrate and vertically embed it into the second composite wet film, so that it penetrates the upper heat sink contact layer and extends into the lower chip contact layer to obtain the third composite wet film.

[0117] S6. Pre-cur the third composite wet film at 78°C for 35 minutes, then heat it to 142°C and cure it for 65 minutes. After cooling, peel it off from the release film and punch it into the predetermined size to obtain the finished smart phase change thermal pad.

[0118] Comparative Example 1 This comparative example is modified from the one disclosed in Example 1 as follows: The lower chip contact layer is omitted. Specifically, the smart phase change thermal pad consists only of the upper heat sink contact layer, and its composition, thickness, and the configuration of the phase change microcapsules and oriented carbon nanotube array are the same as in Example 1.

[0119] Comparative Example 2 This comparative example is modified from the one disclosed in Example 1 as follows: The upper heat sink contact layer is omitted. Specifically, the intelligent phase change thermal pad consists only of the lower chip contact layer, and its composition and thickness are the same as in Example 1; the oriented carbon nanotube array is vertically embedded in this single substrate layer.

[0120] Comparative Example 3 This comparative example is modified from the one disclosed in Example 1 as follows: The phase change microcapsules are omitted. Specifically, the upper heat sink contact layer does not contain any phase change microcapsules; it is composed only of silicone rubber filled with carbon fiber fragments and oriented carbon nanotube arrays.

[0121] Comparative Example 4 This comparative example is modified from the one disclosed in Example 1 as follows: The oriented carbon nanotube array is omitted. Specifically, the thermal pad consists only of an elastic matrix (lower and upper layers) and phase change microcapsules dispersed in the upper layer.

[0122] Comparative Example 5 This comparative example is modified from the one disclosed in Example 1 as follows: The top of the oriented carbon nanotube array does not have a few-layer graphene cap. Specifically, the prepared carbon nanotube array is a purely vertical structure with no horizontal bridging between arrays.

[0123] Comparative Example 6 This comparative example is modified from the one disclosed in Example 1 as follows: Meanwhile, the phase change microcapsules and the oriented carbon nanotube array are omitted. Specifically, the elastic matrix composition and thickness of the smart phase change thermal pad are exactly the same as in Example 1, but the upper heat sink contact layer does not contain any phase change microcapsules, and the entire thermal pad does not contain an oriented carbon nanotube array.

[0124] Comparative Example 7 This comparative example is modified from the one disclosed in Example 1 as follows: The hexagonal boron nitride nanosheets in the lower chip contact layer are replaced with an equal amount of silicone rubber. Specifically, the lower chip contact layer is pure silicone rubber, containing no thermally conductive fillers, and its thickness is the same as in Example 1. The configuration of the upper heat sink contact layer, phase change microcapsules, and oriented carbon nanotube array is consistent with that in Example 1.

[0125] Comparative Example 8 This comparative example is modified from the one disclosed in Example 1 as follows: The carbon fiber fragments in the upper heat sink contact layer were replaced with an equal amount of silicone rubber. Specifically, the upper heat sink contact layer was made of pure silicone rubber, without carbon fiber fragments, and its thickness was the same as in Example 1. The configuration of the lower chip contact layer, phase change microcapsules, and oriented carbon nanotube array was consistent with that in Example 1.

[0126] The physicochemical and application properties of the smart phase change thermal pads prepared in Examples 1-3 and Comparative Examples 1-8 were measured, and the results are shown in Tables 1 and 2. The performance measurement methods are as follows: (1) Methods for determining physicochemical properties Thermal conductivity (vertical direction): The steady-state thermal conductivity in the vertical direction was measured at 25°C using the heat flow meter method (ASTM D5470 standard) and a thermal conductivity meter (such as LaserComp HFM-100). The sample size was 50mm × 50mm, and the thickness was the actual value.

[0127] Thermal resistance: Also based on the ASTM D5470 standard, the overall thermal resistance (including interfacial thermal resistance) is calculated by measuring the temperature difference and heat flow.

[0128] Phase transition properties (phase transition temperature and latent heat): The phase transition peak temperature (melting point) and latent heat (based on the total sample mass) were measured using differential scanning calorimetry (DSC, such as TA Instruments Q20) at a rate of 5 °C / min from 20 °C to 80 °C under a nitrogen atmosphere.

[0129] Hardness: The surface hardness of the sample was measured using a Shore A hardness tester (ASTM D2240 standard) at 25°C, and the average value of 5 points was taken.

[0130] Volume resistivity: Measured at 500V DC using a high-resistivity meter (such as Keysight B2985A) to evaluate electrical insulation performance (critical only for the underlying chip contact layer).

[0131] (2) Application performance testing methods Steady-state temperature test: An SSD test platform was built (using PCIe 5.0 SSD, Phison E26 controller chip, and QLC NAND flash memory). It was run for 30 minutes under constant load (sequential write speed 7GB / s, power 15W). A thermocouple (K type) was attached to the chip surface to measure the stable junction temperature.

[0132] Transient thermal shock test: On the same SSD platform, a transient pulse load (write burst power 25W, lasting 5s) is applied, and the chip peak temperature and recovery time (time required for the temperature to drop to steady state +5℃) are measured.

[0133] Long-term reliability testing: Thermal cycling test (-40℃ to 125℃, 1000 cycles) is performed, followed by measurement of thermal conductivity and thermal resistance change rate to assess performance degradation.

[0134] Table 1. Physicochemical properties of the smart phase change thermal pads of Examples 1-3 and Comparative Examples 1-8 As shown in Table 1, the smart phase change thermal pads in Examples 1-3 all exhibit comprehensive and excellent physicochemical properties. Their core indicators are highly compatible with the requirements of high-power-density SSDs, and they demonstrate a gradient advantage corresponding to the parameter design. The thermal conductivity of all three is in the high range of 12.8–17.6 W / m·K, and their thermal resistance is as low as 0.011–0.015 K·m. 2 / W, in Example 3, due to the higher filling ratio of hexagonal boron nitride nanosheets, carbon fiber fragments, and phase change microcapsules, the areal density of the oriented carbon nanotube array is greater, the thermal conductivity reaches 17.6 W / m·K, and the thermal resistance is as low as 0.011 K·m. 2 / W, which is the optimal value among the three; the parameters in Example 2 are slightly below the lower limit, with a thermal conductivity of 12.8 W / m·K and a thermal resistance of 0.015 K·m. 2 / W, suitable for scenarios with higher requirements for thickness and flexibility. Regarding phase change performance, all embodiments exhibit a clear and stable phase change temperature (48.2–52.1℃) and latent heat (22.4–28.3 J / g), accurately covering the typical thermal shock temperature range of SSD operation, ensuring the realization of transient temperature control. In terms of insulation and structural performance, the volume resistivity of all embodiments remains at 4.6 × 10⁻⁶. 15 ~5.8×10 15 The high insulation level of Ω·cm effectively avoids the risk of short circuits between the chip and the upper conductive components; the ShoreA hardness of 58.2 to 62.3 ensures both the fit between the elastic substrate and the chip and heat sink, and sufficient structural stability to meet the mechanical requirements for installation and use.

[0135] Comparative Example 1, by omitting the lower chip contact layer, although having a thermal conductivity (14.2 W / m·K) and phase transition performance similar to Example 1, exhibits a sharp decrease in volume resistivity to 1.0 × 10⁻⁶. 10 The insulation performance deteriorates significantly at Ω·cm, failing to guarantee the electrical safety of SSDs and highlighting the core insulating role of hexagonal boron nitride nanosheets in the lower chip contact layer.

[0136] Comparative Example 2 omits the upper heatsink contact layer, retaining only the lower chip contact layer structure. Its thermal conductivity is only 5.2 W / m·K, and its thermal resistance is as high as 0.032 K·m. 2 / W, which is much lower than in the example, and there is no phase change related data, proving that the upper heat sink contact layer is not only the supporting basis for the phase change microcapsules, but also constructs an efficient heat conduction path through carbon fiber fragments, which is crucial to the overall heat conduction performance.

[0137] Comparative Example 3, omitting the phase change microcapsules, had the same thermal conductivity and thermal resistance as Example 1 (15.3 W / m·K, 0.013 K·m). 2( / W), but there is no data on phase change temperature and latent heat. It is clear that phase change microcapsules are the only source of phase change temperature control function for thermal pads, and do not affect steady-state thermal conductivity.

[0138] Comparative Example 4, omitting the oriented carbon nanotube array, resulted in a sharp drop in thermal conductivity to 3.6 W / m·K and an increase in thermal resistance to 0.042 K·m. 2 / W, which is only 23.5% of that in Example 1, fully demonstrates that oriented carbon nanotube arrays are the core component for constructing vertically efficient thermal conduction pathways and reducing overall thermal resistance.

[0139] Comparative Example 5, due to the absence of a few-layer graphene cap at the top of the oriented carbon nanotube array, has a slightly lower thermal conductivity (14.1 W / m·K) than Example 1, and a lower thermal resistance (0.014 K·m). 2 The / W) is slightly higher than that of Example 1, which reflects the slight improvement in thermal conductivity due to the lateral bridging effect of the graphene cap. Although it is not a core essential component, it can optimize the overall thermal conductivity.

[0140] Comparative Example 6, which omits both the phase change microcapsules and the oriented carbon nanotube array, exhibits a thermal conductivity of only 2.6 W / m·K and a thermal resistance as high as 0.062 K·m. 2 The sample with the lowest physicochemical properties (W) and no phase transition data indicates that the synergistic effect of the two core functional components is the key to the excellent performance of the embodiment.

[0141] Comparative Example 7 replaced the hexagonal boron nitride nanosheets in the contact layer of the lower chip with pure silicone rubber, reducing the volume resistivity to 1.0 × 10⁻⁶. 12 Ω·cm, thermal conductivity (12.3 W / m·K) and thermal resistance (0.021 K·m) 2 The performance of the hexagonal boron nitride nanosheets (W) was inferior to that of Example 1, indicating that the hexagonal boron nitride nanosheets not only provide insulation but also help improve the thermal conductivity of the underlying layer and optimize the overall heat transfer path.

[0142] Comparative Example 8 replaced the carbon fiber fragments in the upper heatsink contact layer with pure silicone rubber, resulting in a decrease in thermal conductivity to 13.2 W / m·K and an increase in thermal resistance to 0.019 K·m. 2 / W, lower than in Example 1, demonstrates that carbon fiber fragments can effectively enhance the thermal conductivity of the upper layer and reduce the contact thermal resistance with the heat sink, which is crucial for steady-state heat dissipation.

[0143] Table 2 Application performance of the smart phase change thermal pads in Examples 1-3 and Comparative Examples 1-8 As shown in Table 2, Examples 1-3 exhibit comprehensive and excellent thermal management performance in high power density SSD applications. They demonstrate outstanding steady-state heat dissipation, transient thermal shock suppression, and long-term reliability, exhibiting gradient characteristics that match the parameter design. The steady-state temperature of all three is controlled between 55.2 and 57.6°C, the transient peak temperature is only between 65.3 and 67.8°C, the recovery time is as short as 10.5 to 12.3 seconds, and the change rate of thermal conductivity after thermal cycling is only 1.2% to 1.8%, fully demonstrating the synergistic advantages of "high-efficiency thermal conduction + intelligent temperature control + structural stability".

[0144] Comparative Example 1, due to the omission of the lower chip contact layer, exhibited higher steady-state temperature (60.3℃) and transient peak temperature (70.5℃) than Example 1, with a recovery time extended to 15.2s. The rate of change in thermal conductivity after thermal cycling (3.2%) also significantly increased. This is because the lack of insulating support and interface optimization from the lower hexagonal boron nitride nanosheets led to a decrease in interface adhesion and thermal conductivity during long-term use, confirming the crucial role of the lower chip contact layer in overall thermal management stability.

[0145] Comparative Example 2 omits the upper heat sink contact layer and only retains the lower chip contact layer structure. Its steady-state temperature (75.4℃) and transient peak temperature (85.6℃) are significantly higher than those of the Example, and there is no recovery time data. The change rate after thermal cycling is as high as 6.1%, indicating that the upper heat sink contact layer is not only the supporting foundation of the phase change microcapsule, but also constructs an efficient heat conduction path through carbon fiber fragments. Without it, the chip heat cannot be quickly dissipated, and the heat dissipation capability after transient temperature control is completely lost.

[0146] Comparative Example 3 omits the phase change microcapsule, and its steady-state temperature (55.2℃) is exactly the same as that of Example 1. However, the transient peak temperature rises sharply to 80.4℃, and there is no recovery time data. This clearly shows that the core function of the phase change microcapsule is to buffer the instantaneous thermal shock and suppress the temperature surge. It has no direct impact on steady-state heat dissipation, but it can prevent the chip from reducing its frequency due to instantaneous high temperature.

[0147] Comparative Example 4, which omitted the oriented carbon nanotube array, showed a significant increase in both steady-state temperature (70.3℃) and transient peak temperature (75.5℃), with the recovery time extended to 20.5s and a higher rate of change after thermal cycling (4.6%). This demonstrates that the oriented carbon nanotube array is the core component for constructing a vertical and efficient heat conduction pathway. Without it, heat cannot be quickly transferred to the heat sink, affecting both steady-state heat dissipation efficiency and making it difficult to dissipate the latent heat absorbed by the phase change microcapsules, thus prolonging the temperature recovery time.

[0148] Comparative Example 5, due to the absence of a few-layer graphene cap on the top of the oriented carbon nanotube array, exhibited a slightly higher steady-state temperature (58.2℃) and transient peak temperature (68.4℃) than Example 1, and a significantly longer recovery time (18.3s). This indicates that the lateral bridging effect of the graphene cap can promote the uniform diffusion of heat in the top layer, avoid the accumulation of local hot spots, and accelerate temperature recovery. Although it is not a core essential component, it can further optimize thermal management efficiency.

[0149] Comparative Example 6, which omits both the phase change microcapsule and the oriented carbon nanotube array, exhibits the worst performance among all samples. It has the highest steady-state temperature (80.5℃), the highest transient peak temperature (90.3℃), and the highest rate of change after thermal cycling (8.2%). Furthermore, it lacks recovery time data, which fully demonstrates that the synergistic effect of the two core functional components is the key to the excellent performance of the example. The thermal management capability will be completely degraded when either or both are missing.

[0150] In Comparative Example 7, the hexagonal boron nitride nanosheets in the contact layer of the lower chip were replaced with pure silicone rubber. The steady-state temperature (65.4℃) and transient peak temperature (75.6℃) were significantly higher than those in Example 1, the recovery time (16.4s) was prolonged, and the rate of change after thermal cycling (3.6%) was increased. This indicates that the hexagonal boron nitride nanosheets can not only ensure insulation safety, but also help improve the thermal conductivity of the lower layer and optimize the heat transfer path. Their absence will lead to an increase in interlayer thermal resistance and a decrease in overall heat dissipation performance.

[0151] Comparative Example 8 replaced the carbon fiber fragments in the upper heat sink contact layer with pure silicone rubber. The steady-state temperature (62.3℃) and transient peak temperature (72.5℃) were higher than those in Example 1, the recovery time (14.3s) was prolonged, and the change rate after thermal cycling (2.9%) was slightly higher. This proves that the carbon fiber fragments can enhance the thermal conductivity between the upper layer and the heat sink and reduce the contact thermal resistance. The absence of carbon fiber fragments will slow down the heat transfer speed to the external heat sink and affect the steady-state and transient heat dissipation effects.

[0152] The range descriptions used herein, such as numerical ranges and proportional ranges, include all possible sub-ranges and single numerical values ​​within that range. For example, the range descriptions of "1 to 6" or "1 to 6" cover all sub-ranges (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6) between 1 and 6. Unless otherwise specified, the terms "including" and "contains" as used herein mean "including but not limited to"; relational terms such as "first" and "second" are used only to distinguish different entities or operations and do not imply an actual order or relationship; "and / or" indicates that multiple situations can exist individually or simultaneously; expressions such as "at least one," "multiple," and "at least one" refer to any combination of the corresponding objects, including combinations of single or multiple objects. The proportional relationships mentioned herein, such as mass ratios and molar ratios, should be understood as the correspondence between the first and second terms of a proportional formula, according to the order of description. The raw materials, reagents, instruments, and equipment used herein can all be obtained through commercial purchase or prepared using existing methods.

[0153] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A smart phase change thermal pad for SSDs, characterized in that, The intelligent phase change thermal pad includes: An elastic substrate, comprising a lower chip contact layer and an upper heat sink contact layer, wherein the lower chip contact layer is composed of hexagonal boron nitride nanosheets filled with silicone rubber, and the upper heat sink contact layer is composed of carbon fiber fragments filled with silicone rubber. Phase change microcapsules are dispersed in the upper heat sink contact layer. The core material of the phase change microcapsules is a composite of n-tetracosane, n-triane and zinc oxide nanowires, and the wall material is melamine-formaldehyde resin. A directional carbon nanotube array is vertically embedded in the elastic matrix and penetrates the lower chip contact layer and the upper heat sink contact layer.

2. The smart phase change thermal pad for SSDs according to claim 1, characterized in that, The thickness of the intelligent phase change thermal pad is 120–250 μm; The thickness of the lower chip contact layer is 20–50 μm; In the lower chip contact layer, the mass fraction of the hexagonal boron nitride nanosheets is 20-40%. The thickness of the upper heat sink contact layer is 100–200 μm; In the upper heat sink contact layer, the mass fraction of the carbon fiber fragments is 10-25%.

3. The intelligent phase change thermal pad for SSDs according to claim 1, characterized in that, The mass of the phase change microcapsule is 15-30% of the total mass of the upper heat sink contact layer; In the phase change microcapsules, the average particle size of the core material is 20–80 μm, and the average thickness of the wall material is 0.5–2 μm; The areal density of the oriented carbon nanotube array is 10–30 mg / cm³. 2 .

4. The smart phase change thermal pad for SSDs according to claim 3, characterized in that, The preparation method of the phase change microcapsules includes the following steps: S101. At 60-80℃, n-tetracosane, n-triane and zinc oxide nanowires are mixed and ultrasonically treated to obtain a composite core material. S102. Melamine is added to an aqueous formaldehyde solution and reacted under alkaline conditions at 60-75°C for 30-90 minutes to obtain an aqueous solution of melamine-formaldehyde prepolymer. S103. Under stirring, the composite core material is added to the aqueous solution of the melamine-formaldehyde prepolymer containing emulsifier, and emulsification is performed using a high-speed shear emulsifier to obtain an oil / water emulsion. S104. The oil / water emulsion is heated to 60-75°C, kept at the temperature and stirred continuously for 2-5 hours to allow the melamine-formaldehyde prepolymer to undergo a polymerization reaction at the droplet interface of the composite core material, thereby obtaining a mixture containing microcapsules. S105. The mixture is cooled, filtered, washed and dried to obtain the phase change microcapsule powder.

5. The smart phase change thermal pad for SSDs according to claim 4, characterized in that, The mass ratio of n-tetracosane to n-triane is 1:(1-3); The mass of the zinc oxide nanowires is 1-5% of the total mass of the n-tetracosane and the n-triane; The molar ratio of melamine to formaldehyde is 1:(3-4); The mass ratio of the composite core material to the solids in the melamine-formaldehyde prepolymer aqueous solution is (5-10):

1. The mass of the emulsifier is 1 to 5% of the mass of the melamine-formaldehyde prepolymer aqueous solution.

6. The smart phase change thermal pad for SSDs according to claim 1, characterized in that, The method for preparing the oriented carbon nanotube array includes the following steps: S201. Deposit a thin film of iron catalyst on the growth substrate; S202. The growth substrate with iron catalyst deposited is placed in a chemical vapor deposition reactor, heated to the growth temperature under a protective gas atmosphere, and then ethylene reaction gas is introduced to grow a vertically oriented carbon nanotube array. S203. After the carbon nanotube array is grown, maintain the reactor temperature, stop the introduction of ethylene reaction gas, and introduce methane reaction gas. Use plasma-enhanced chemical vapor deposition to grow a few-layer graphene cap on the top of the carbon nanotube array in situ, and obtain a substrate with a oriented carbon nanotube array.

7. The smart phase change thermal pad for SSDs according to claim 6, characterized in that, The thickness of the iron catalyst film is 1–10 nm; The carbon nanotube array is grown at a temperature of 600–800℃ for a time of 10–30 min. The plasma-enhanced chemical vapor deposition method is applied at a temperature of 600–800℃ for a duration of 30–120 seconds.

8. A method for preparing a smart phase change thermal pad for SSDs according to any one of claims 1 to 7, characterized in that, The method includes the following steps: S1. Mix silicone rubber and hexagonal boron nitride nanosheets in a solvent and stir to obtain a uniform lower chip contact layer paste. S2. Mix silicone rubber and carbon fiber fragments in a solvent and stir to obtain the upper heat sink contact layer slurry. S3. The lower chip contact layer paste and the upper heat sink contact layer paste are sequentially coated on the substrate to obtain the first composite wet film. S4. The phase change microcapsules are uniformly dispersed on the surface of the upper heat sink contact layer of the first composite wet film to obtain the second composite wet film. S5. Align the substrate with the oriented carbon nanotube array with the second composite wet film, and transfer the oriented carbon nanotube array from the growth substrate and vertically embed it into the second composite wet film through an imprinting process, so that it penetrates the upper heat sink contact layer and extends into the lower chip contact layer to obtain the third composite wet film. S6. The third composite wet film is pre-cured at 70-80°C for 20-40 minutes, then heated to 120-150°C for 40-80 minutes. After cooling, peeling and punching, the finished smart phase change thermal pad is obtained.

9. The method for preparing a smart phase change thermal pad for SSDs according to claim 8, characterized in that, The pressure of the imprinting process is 0.5–5 MPa, and the imprinting temperature is 60–90°C.

10. The method for preparing a smart phase change thermal pad for SSDs according to claim 8, characterized in that, The coating thickness of the wet film of the lower chip contact layer is controlled to be 30-80 μm, and the coating thickness of the wet film of the upper heat sink contact layer is controlled to be 120-250 μm.

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