High-reliability heat-conducting silicone grease for semiconductor packaging and preparation method and application thereof

Abstract

The application relates to the technical field of thermal interface materials, in particular to a high-reliability heat-conducting silicone grease for semiconductor packaging and a preparation method and application thereof. The heat-conducting silicone grease is prepared by addition reaction curing of a mixture containing the following components: a silicone oil system containing vinyl silicone oil and hydrogen-containing silicone oil which can undergo addition reaction; heat-conducting fillers, the total mass of which accounts for more than 90% of the total mass of the heat-conducting silicone grease; a platinum gold catalyst; and a heat-resistant agent which is an organic heat-resistant hybrid formed by modification of a silane coupling agent and introduction of metal ion coordination. The application uses a high proportion of multiple micron-sized heat-conducting fillers which are surface-modified, simultaneously uses special heat-resistant agents and silane coupling agents to enhance the interface bonding of the fillers and the matrix resin, and uses a three-dimensional crosslinking network formed by addition reaction to stably encapsulate the same, realizes ultra-low contact thermal resistance, significantly improves the heat dissipation efficiency, and effectively reduces the gap in the heat conduction path.

Description

Technical Field

[0001] This invention relates to the field of thermal interface materials technology, and in particular to a high-reliability thermal grease for semiconductor packaging, its preparation method, and its application. Background Technology

[0002] With the continuous increase in power density of high-performance semiconductor devices such as GPUs and AI chips, the heat generated during their operation is also increasing dramatically. Effective heat dissipation has become crucial for ensuring stable chip performance and long-term reliability. In this heat dissipation system, the thermal interface material between the chip package and the heat sink plays an indispensable role. Its task is to fill the microscopically uneven contact surface, expel air, and establish an efficient heat conduction path. Among many thermal interface materials, thermal grease is widely used due to its good wettability, ease of application, and relatively excellent thermal conductivity.

[0003] Traditional thermal greases are primarily composed of silicone oil and a large amount of inorganic thermally conductive fillers (such as alumina, zinc oxide, and boron nitride) mixed through physical and mechanical processes, resulting in a paste-like form. The performance of these materials largely depends on the proportion and properties of the thermally conductive fillers. To improve thermal conductivity, the industry commonly employs methods that increase the amount of filler added. However, this method quickly encounters a bottleneck: when the filler content exceeds a certain threshold, the material viscosity rises sharply, leading to difficulties in application and the formation of a uniform thin layer. Furthermore, during the extrusion process between the chip and the heatsink, an excessively high filler ratio can easily cause filler particles to aggregate or scratch the interface, potentially reducing the actual contact area and thermal conductivity. A more fundamental challenge lies in the stability of this physically mixed system during long-term use. As a continuous phase, silicone oil may migrate, volatilize, or be pumped out under harsh conditions of prolonged high-temperature or high-low-temperature cycling, causing the paste to dry and crack. This results in a significant increase in thermal resistance over time, a phenomenon known as "oil seepage" or "drying," ultimately affecting the durability of the heat dissipation effect.

[0004] To improve stability, some technical solutions attempt to introduce partially cross-linked structures or add special thickeners and coupling agents into the silicone oil matrix. These methods can alleviate silicone oil migration to some extent, but they often introduce new limitations. For example, partial cross-linking may affect the initial wettability and thixotropy of the material, making it difficult to fully spread and fill microscopic voids under low pressure. While the introduction of certain additives improves short-term shape retention, their thermal stability at long-term high temperatures may be insufficient, failing to meet the reliability requirements of high-end chips for interface materials aging for tens of thousands of hours or even longer. Furthermore, the interfacial bonding strength between the surface of high-proportion fillers and the silicone matrix is ​​another key factor affecting long-term thermal stability. If the interfacial bonding is weak, micro-gaps are easily generated under thermal stress, becoming points of increased thermal resistance. Although treating the filler surface with silane coupling agents is a common method to enhance the interface, under ultra-high filler density and long-term thermal aging conditions, the bonding force provided by conventional coupling agents is still insufficient, and the interface may gradually fail.

[0005] Therefore, developing a novel thermal interface material that achieves ultra-low thermal resistance while maintaining excellent workability, and, most importantly, high reliability with high thermal resistance retention under harsh environments such as long-term high and low temperature shocks, has become a clear and urgent technical requirement in semiconductor packaging, especially in the field of heat dissipation for high-end computing and artificial intelligence chips. Existing physically hybrid thermal grease systems still have room for improvement in simultaneously meeting these comprehensive performance indicators. Summary of the Invention

[0006] This application aims to overcome the shortcomings of existing thermal greases, such as high thermal resistance, insufficient long-term stability, and low interface coverage, which make it difficult to simultaneously meet the requirements of high power density semiconductor chips for ultra-low thermal resistance and high reliability. Therefore, it provides a high-reliability thermal grease for semiconductor packaging, its preparation method, and its application to overcome the above-mentioned deficiencies.

[0007] To achieve the above-mentioned objectives, the present invention is implemented through the following technical solution: Firstly, the present invention provides a high-reliability thermal grease for semiconductor packaging. It is made by curing an addition reaction of a mixture containing the following components: Silicone oil systems include vinyl silicone oils and hydrogen-containing silicone oils that can undergo addition reactions; Thermally conductive filler, the total mass of which accounts for more than 90% of the total mass of the thermally conductive silicone grease; Platinum catalyst; and The heat resistant agent is an organic heat-resistant hybrid formed by modifying a silane coupling agent and introducing metal ions for coordination.

[0008] As shown in the background section, existing thermal greases, in pursuit of lower interfacial thermal resistance, require the introduction of the highest possible proportion of thermally conductive fillers. However, this typically leads to a sharp increase in the viscosity of the mixture, making application and spreading difficult. Furthermore, under long-term high-temperature or thermal cycling conditions, traditional physically mixed thermal grease systems are prone to migration, volatilization, or separation from the fillers (often manifested as "oil seepage" or "drying") of the silicone oil, which acts as the continuous phase. This results in a significant increase in actual contact thermal resistance over time and a decrease in interfacial reliability. Existing attempts to improve stability by adding coupling agents or thickeners often compromise on long-term thermal aging performance or process applicability, making it difficult to systematically solve the problem of synergistically improving high thermal conductivity, high workability, and high long-term reliability.

[0009] Therefore, the core of this application lies in fundamentally changing the formation mechanism of the system by adopting an addition reaction curing system composed of vinyl silicone oil, hydrogen-containing silicone oil, and a platinum catalyst, instead of simple physical blending. This change allows the silicone oil base components to form a three-dimensional cross-linked network structure through chemical reaction. This network structure plays a crucial "anchoring" and "stabilizing" role in the presence of a high proportion of thermally conductive filler (more than 90% by mass). It not only effectively binds the silicone oil molecules, which serve as the dispersion medium, significantly inhibiting their migration and pumping tendencies during long-term use, thereby fundamentally improving the morphological stability of the material, but this cross-linked network itself also provides the necessary mechanical support to withstand extremely high filler loadings. This allows the material to maintain good process flowability before curing while achieving ultra-high thermally conductive filler loadings, and to form a stable interface layer with a certain cohesive strength after curing, avoiding the common problems of paste hardening or filler sedimentation under high filling conditions.

[0010] However, relying solely on addition reaction curing to encapsulate high-proportion fillers is insufficient to address the long-term thermal reliability challenges under extreme temperature conditions. This is because the interface between the organosilicon network and inorganic filler particles remains a weak point under prolonged high thermal stress. The binding force provided by conventional silane coupling agents may weaken under long-term high temperatures, leading to an increase in interfacial thermal resistance. To overcome these problems, this invention further introduces an organic heat-resistant hybrid, modified with a silane coupling agent and further coordinated with metal ions, as a dedicated heat-resistant agent. This component is designed with multiple functions: firstly, the silane portion in its molecular structure can form a strong chemical bond with the filler surface, providing a stronger primary interfacial bond than ordinary coupling agents; secondly, the hybrid structure constructed through metal ion coordination, along with the introduced heat-resistant organic groups, can form a transition layer with higher thermal stability between the filler and the organosilicon matrix. This transition layer can more effectively delay or block the spread of thermal degradation reactions to the interface and matrix at high temperatures, thereby protecting the integrity of the overall cross-linked network structure and interfacial bonding. In other words, this special heat-resistant agent is not a simple physical additive, but is designed into the system as an integration of interface reinforcement and thermal protection.

[0011] Therefore, this application constructs a multi-layered synergistic system solution. First, the three-dimensional cross-linked network formed by the addition reaction constitutes the "skeleton" of the system, providing a structural basis for the stable existence and long-term morphological maintenance of the ultra-high proportion of filler, directly addressing the pain point of "oil drying". Meanwhile, the special heat-resistant hybrid acts as a highly efficient "interface strengthener and heat stabilizer," tightly adhering to the filler surface and integrating into the cross-linked network, specifically addressing the interfacial degradation problem under long-term thermal aging. These two work synergistically to ensure the durability of the entire composite material system under harsh thermal environments, even with an extremely high filler ratio and highly optimized thermal conductivity.

[0012] The final technical effect is holistic: the prepared thermal grease not only achieves a significant reduction in initial thermal resistance, but more importantly, during use, especially under long-term high temperature or high and low temperature shock conditions, the stability of thermal resistance is greatly improved, and the interface bonding state is maintained well, thus meeting the stringent requirements of high-end semiconductor packaging for the long-term reliability of interface heat dissipation materials.

[0013] Preferably, the thermally conductive filler comprises at least one of metal powder and ceramic powder.

[0014] Preferably, the thermal grease comprises the following components by weight: 4-18 parts vinyl silicone oil, 3-8 parts hydrogen-containing silicone oil, 90-110 parts thermally conductive filler, 1-5 parts heat-resistant agent, 1-2 parts silane coupling agent, and 1-5 parts platinum catalyst. The thermally conductive filler comprises at least three of the following: aluminum powder, aluminum nitride, aluminum oxide, zinc oxide, and boron nitride.

[0015] Preferably, the silicone oil system further includes phenyl vinyl silicone oil; and / or, methyl phenyl silicone oil.

[0016] Preferably, phenyl vinyl silicone oil has a refractive index ≥1.42 and a phenyl content ≥10%, while methyl phenyl silicone oil has a refractive index ≥1.45 and a phenyl content ≥10%. Their structural formulas are as follows: .

[0017] Preferably, the average particle size D50 of the thermally conductive filler is less than 45 μm.

[0018] Preferably, the organic heat-resistant hybrid is formed by reacting a nitrogen-containing heterocyclic compound with a silane coupling agent and then coordinating it with metal ions.

[0019] The core function of the organic heat-resistant hybrid described in this application lies in systematically strengthening the interface between the filler and the organosilicon matrix at the molecular level and improving the thermal stability of the entire composite material system, thereby directly supporting and enhancing the high reliability sought in the main claim. Specifically, it does not simply use common silane coupling agents or heat-resistant additives, but creatively integrates the heat-resistant framework of nitrogen-containing heterocycles, the coupling ability of silanes, and the coordination bonds of metal ions into a single molecular structure. This design allows the hybrid to form a strong and durable chemical bond with the surface of the inorganic filler through the silane ends. At the same time, the hybrid network structure formed by the coordination of metal ions and the high thermal stability of the nitrogen-containing heterocycles together construct a thermal barrier around the filler. This barrier not only more effectively blocks heat transfer to the organosilicon resin network, delaying its thermal oxidative degradation, but also maintains the integrity of the interfacial bonding under long-term thermal stress, preventing the increase in thermal resistance due to interfacial failure.

[0020] Existing technologies typically employ two separate approaches to improve interface and heat resistance: one is to use silane coupling agents to improve compatibility, and the other is to add heat-resistant fillers or additives. This solution, however, integrates the "coupling" and "heat resistance" functions into a unified molecular structure and chemically integrates them, constructing a unique hybrid structure by introducing metal coordination bonds. This design allows the heat resistance function to be directly anchored to the interface through chemical bonds, achieving a synergistic effect of interface strengthening and bulk heat resistance.

[0021] Preferably, the nitrogen-containing heterocyclic compound is 3-amino-1,2,4-triazole, the silane coupling agent is chloropropyltriethoxysilane, and the metal ion is zinc ion.

[0022] The heat-resistant agent in this application is modified 3-amino-1,2,4-triazole (ATA). Its mechanism of action as a strong heat-resistant agent is as follows: The modified ATA is a bifunctional molecule with an inorganic affinity group (silane) at one end and an organic functional group (triazole ring + amino group) at the other. When treating the filler, the ethoxy group hydrolyzes into highly active silanol groups, which interact with the M-OH groups in the filler (M represents a metal ion) to generate a stable MO-Si structure. At this point, the organosilane molecule is permanently grafted onto the filler surface. The hydrophilic hydroxyl groups on the modified filler surface are replaced by the triazole ring and amino group. Since the triazole ring is an aromatic heterocycle with high delocalization energy, it has a very high thermal decomposition temperature. Introducing it into the interface is equivalent to constructing a "thermal barrier" on the filler surface, which can delay heat transfer and the thermal degradation of the resin at the interface. The triazole ring is a nitrogen-rich structure. At high temperatures or during combustion, it can decompose to produce non-flammable gases (such as N2 and NH3), playing a role in gas-phase dilution and flame retardancy.

[0023] The final hybrid product is a coordination polymer network composed of Zn-triazole rings, with a silane arm extending from each grid node and connected by Si-O-Si bonds to form a second siloxane network. The two networks interpenetrate and intersect, forming a dual-network hybrid material. This material possesses exceptional heat resistance due to the combined effects of the aromaticity of the triazole rings, the strength of the Zn-N coordination bonds, and the strength of the Si-O-Si covalent bonds. The surface of the structure contains abundant Si-OH or Si-OEt, which can chemically bond with silicone rubber, silicone resin, etc., through condensation reactions to achieve seamless composites. Therefore, this hybrid can be used as a heat-resistant agent in the preparation of silicone grease.

[0024] Preferably, the heat-resistant agent is prepared by the following method: (1) The synthesis process of modified ATA is as follows: 1. Under nitrogen protection, weigh 3-amino-1,2,4-triazole and add it to a dry three-necked flask. Add anhydrous toluene, heat and stir magnetically until the solid is completely dissolved. 2. After the solution cools to room temperature, add triethylamine to the flask. At this time, the solution becomes turbid. Under nitrogen protection, slowly add 3-chloropropyltriethoxysilane dropwise while stirring at room temperature during the addition. 3. Heating under reflux, during which the white precipitate gradually increases and the solution color changes from colorless to light brown; 4. After the reaction is complete, cool to room temperature and filter the reaction solution under reduced pressure, rinsing the filter cake with a small amount of anhydrous toluene during the process; 5. Transfer the filtrate to a round-bottom flask and remove the solvent under reduced pressure to obtain a pale yellow liquid, which is the crude product; 6. Add 10 mL of anhydrous acetonitrile to the crude product, stir to dissolve, transfer to a separatory funnel, and extract and wash with n-hexane to remove unreacted KH-230. 7. Collect the acetonitrile layer, perform rotary evaporation, and dry the final product in an oven to obtain KH-230 modified ATA.

[0025] The reaction equation for this process is as follows:

[0026] (2) The process of introducing Zn ions to prepare hybrids is as follows: 1. Under nitrogen protection, add modified ATA (hereinafter referred to as L-Si) to a dry three-necked flask, add anhydrous DMF, and stir until completely dissolved; 2. Dissolve Zn(NO3)2·6H2O in anhydrous DMF, and slowly add the solution dropwise to L-Si solution at a rate of 1 drop / second; 3. Stirring reaction; 4. After stirring, a clear reaction solution is obtained. Anhydrous diethyl ether is added to precipitate the solution. After filtration, the solution is washed with anhydrous diethyl ether and the washings are dried under vacuum to obtain the preliminary product. 5. Add anhydrous DMF to the initial product, and slowly add deionized water dropwise to the solution while stirring vigorously to induce silane hydrolysis; 6. Transfer the solution to a round-bottom flask and stir in a water bath. During this process, you can see the solution gradually become cloudy or turn into a gel, which is the crude product. 7. After cooling to room temperature, centrifuge the crude product, collect the precipitate, and wash it sequentially with anhydrous DMF, ethanol, and water. 8. Place the washed items in an oven to dry, and the final heat-resistant agent is obtained.

[0027] Secondly, the present invention also provides a method for preparing the aforementioned high-reliability semiconductor packaging thermal grease, comprising the following steps: S1. Filler pretreatment: The thermally conductive filler is mixed with the heat-resistant agent and silane coupling agent, and then subjected to high-speed stirring and ball milling to obtain a surface-modified composite thermally conductive filler; S2. Mixing and dispersing: The silicone oil system and the composite thermally conductive filler obtained in step S1 are stirred and mixed under heating and vacuum conditions to obtain a uniform slurry; S3. Addition curing: A platinum catalyst is added to the slurry, and a curing reaction is carried out under vacuum and heating conditions to obtain the thermally conductive silicone grease.

[0028] Preferably, in step S1, the high-speed stirring speed is 1000-2500 r / min, and the ball-to-material mass ratio of the ball mill is 3:1. Step S2 is carried out in a planetary mixer at a stirring speed of 10-25 Hz, a mixing temperature of 80-120℃, and a vacuum degree of not less than -0.09 MPa. The curing temperature for step S3 is 80-100℃.

[0029] Thirdly, the present invention also provides a heat dissipation interface for a semiconductor device, which is obtained by curing the thermal grease described above or the thermal grease prepared by the method described above.

[0030] The thermal grease proposed in this invention brings the following beneficial effects: (1) By compounding a variety of surface-modified micron-sized thermally conductive fillers in a high proportion and using a three-dimensional cross-linked network formed by addition reaction to solidify and encapsulate them, ultra-low contact thermal resistance (≤0.045℃·cm) was achieved. 2 / W), significantly improving heat dissipation efficiency; (2) Special heat-resistant agents and silane coupling agents enhance the interfacial bonding between the filler and the matrix resin, so that the cured material has a high and stable interfacial coverage (>90%) between the chip and the heat sink, effectively reducing the voids in the heat conduction path. (3) Based on the synergistic effect of phenyl vinyl silicone oil, modified heat-resistant hybrid and cross-linked structure, the material exhibits a very small change rate of thermal resistance (<10%) after long-term high temperature and high humidity, high and low temperature shock and other harsh aging tests, showing excellent long-term reliability. (4) The pretreatment of fillers, vacuum dispersion and medium temperature curing process used is mild and controllable, with good process repeatability and feasibility for large-scale production. Detailed Implementation

[0031] The present invention will be further described below with reference to specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0032] Example 1 (1) Preparation of modified heat-resistant agent (L-Si-Zn hybrid): Under nitrogen protection, 0.84 g of 3-amino-1,2,4-triazole was added to a dry three-necked flask, followed by 20 mL of anhydrous toluene. The mixture was heated to 45 °C and stirred until completely dissolved. After cooling to room temperature, 1.67 mL of triethylamine was added, and 2.65 mL of 3-chloropropyltriethoxysilane (KH-230) was slowly added dropwise under nitrogen protection at a rate of 1 drop / second. The reaction mixture was then refluxed at 120 °C for 22 hours. After the reaction was complete, the mixture was cooled and filtered. The filtrate was concentrated under reduced pressure to obtain a pale yellow crude product. The crude product was dissolved in 10 mL of anhydrous acetonitrile, then extracted and washed with 10 mL of n-hexane. The acetonitrile phase was collected, and the solvent was removed by rotary evaporation. The product was then dried in an oven at 50 °C for 10 hours to obtain the intermediate L-Si.

[0033] Under nitrogen protection, 2.88 g of L-Si was added to a dry three-necked flask, followed by 20 mL of anhydrous N,N-dimethylformamide (DMF) and stirred until dissolved. 1.49 g of zinc nitrate hexahydrate was dissolved in 10 mL of anhydrous DMF, and this solution was slowly added dropwise to the L-Si solution at a rate of 1 drop / second. The reaction was stirred at 55 °C for 16 hours. After the reaction was complete, anhydrous diethyl ether was added to precipitate the product, which was then filtered, washed with diethyl ether, and dried under vacuum at 45 °C for 4 hours to obtain the preliminary product. The preliminary product was dissolved in 20 mL of DMF (1:1 volume ratio), and 0.8 mL of deionized water was slowly added dropwise. The mixture was stirred at 70 °C for 18 hours. After cooling, the reaction solution was centrifuged, and the precipitate was washed three times each with DMF, ethanol, and water, and finally dried in an oven at 60 °C for 12 hours to obtain the final product: the modified heat-resistant agent L-Si-Zn hybrid.

[0034] 2) Preparation of thermal grease: Raw materials: 10 parts by weight of vinyl silicone oil (vinyl content 0.72%, viscosity 200 mPa·s), 5 parts by weight of double-ended vinyl phenyl silicone oil (vinyl content 0.62%, phenyl content 12%, viscosity 500 mPa·s), 3 parts by weight of methyl phenyl silicone oil (phenyl content 10%, viscosity 1000 mPa·s), 6 parts by weight of end-hydrogen silicone oil (hydrogen content 0.38%, viscosity 250 mPa·s), 1 part by weight of platinum catalyst (divinyltetramethyldisiloxane platinum complex, platinum content 3000ppm), 1 part by weight of inhibitor (ethynylcyclohexanol), 1 part by weight of silane coupling agent (γ-(2,3-epoxypropoxy)propyltrimethoxysilane, KH-560), and 2 parts by weight of modified heat resistant agent prepared in step (1). The thermally conductive filler consists of: 70 parts by mass of spherical aluminum powder with an average particle size D50 = 10 μm, 10 parts by mass of spherical aluminum nitride with an average particle size D50 = 10 μm, 11 parts by mass of α-alumina with an average particle size D50 = 5 μm (α phase content > 95%), 5 parts by mass of zinc oxide with an average particle size D50 = 0.2 μm, and 2 parts by mass of cerium oxide with an average particle size D50 = 50 nm.

[0035] Preparation steps: a) Filler pretreatment: Aluminum powder, aluminum nitride, alumina, zinc oxide, cerium oxide, modified heat-resistant agent, and silane coupling agent (KH-560) were all added to a powder modifier and stirred at high speed for 1 hour at 90℃ and 1500 r / min. Then, the mixture was transferred to a ball mill and ball-milled for 1 hour at a ball-to-material mass ratio of 3:1 and a speed of 500 r / min to obtain a surface-modified composite thermally conductive filler.

[0036] b) Mixing and Dispersion: Vinyl silicone oil, phenyl vinyl silicone oil, methyl phenyl silicone oil, hydrogen-containing silicone oil, and inhibitors were added to a planetary mixer and heated to 120°C. Then, the composite thermally conductive filler obtained in step a) was added, and the mixture was stirred for 2 hours under a vacuum of -0.095 MPa and a stirring speed of 25 Hz (approximately 500 r / min). During this period, the mixer was stopped and the slurry was scraped every 15 minutes to ensure uniform mixing and obtain a viscous and uniform slurry.

[0037] c) Addition curing: A platinum catalyst was added to the above slurry, and the mixture was degassed for 30 minutes under a vacuum of -0.095 MPa. It was then cured in an oven at 100°C for 1.5 hours to obtain the target thermal grease.

[0038] Example 2 The difference between this embodiment and Embodiment 1 lies in the raw material ratio and some filler parameters, in order to demonstrate the implementation effect of different formulations.

[0039] Raw materials: 4 parts by weight of vinyl silicone oil (vinyl content 0.42%, viscosity 500 mPa·s), 10 parts by weight of side-chain vinyl phenyl silicone oil (vinyl content 0.5%, phenyl content 15%, viscosity 800 mPa·s), 1 part by weight of methyl phenyl silicone oil (phenyl content 12%, viscosity 800 mPa·s), 3 parts by weight of end-hydrogen silicone oil (hydrogen content 0.18%, viscosity 1000 mPa·s), 1 part by weight of platinum catalyst, 2 parts by weight of inhibitor (ethynylcyclohexanol), 2 parts by weight of silane coupling agent (KH-560), and 5 parts by weight of modified heat resistant agent (prepared in the same way as in Example 1). The thermally conductive filler consists of: 70 parts by mass of flake aluminum powder with an average particle size D50 = 1 μm, 20 parts by mass of spherical aluminum nitride with an average particle size D50 = 5 μm, 10 parts by mass of α-alumina with an average particle size D50 = 1 μm, 15 parts by mass of zinc oxide with an average particle size D50 = 0.1 μm, 2 parts by mass of flake boron nitride with an average particle size D50 = 8 μm, and 5 parts by mass of cerium oxide.

[0040] In preparation step a), the high-speed stirring speed was 1000 r / min for 2 hours; the ball milling speed was 200 r / min for 1 hour. In step b), the planetary stirring temperature was 80℃, the stirring speed was 10 Hz (approximately 200 r / min), and the vacuum degree was -0.09 MPa. In step c), the curing temperature was 80℃ for 2 hours. The rest was the same as in Example 1.

[0041] Example 3 The difference between this embodiment and Embodiment 1 lies in the raw material ratio, showcasing a high vinyl silicone oil content and another filler combination.

[0042] Raw materials: 18 parts by weight of vinyl silicone oil (vinyl content 1.92%, viscosity 100 mPa·s), 8 parts by weight of phenyl vinyl silicone oil (vinyl content 0.22%, phenyl content 10%, viscosity 3000 mPa·s), 5 parts by weight of methyl phenyl silicone oil (phenyl content 15%, viscosity 5000 mPa·s), 8 parts by weight of hydrogen-terminated silicone oil (hydrogen content 0.7%, viscosity 20 mPa·s), 5 parts by weight of platinum catalyst, 3 parts by weight of inhibitor (ethynylcyclohexanol), 1.5 parts by weight of silane coupling agent (γ-aminopropyltriethoxysilane, KH-550), and 1 part by weight of modified heat resistant agent (prepared in the same way as in Example 1). The thermally conductive filler consists of: 75 parts by mass of spherical aluminum powder with an average particle size D50 = 20 μm, 8 parts by mass of spherical aluminum nitride with an average particle size D50 = 25 μm, 15 parts by mass of α-alumina with an average particle size D50 = 20 μm, 5 parts by mass of rod-shaped zinc oxide with an average particle size D50 = 8 μm, 1 part by mass of plate-shaped boron nitride with an average particle size D50 = 12 μm, and 2.5 parts by mass of cerium oxide.

[0043] In preparation step a), the high-speed stirring speed was 2500 r / min for 0.5 hours; the ball milling speed was 600 r / min for 0.5 hours. In step b), the planetary stirring temperature was 110℃, the stirring speed was 20 Hz, and the vacuum degree was -0.092 MPa. In step c), the curing temperature was 90℃ for 1 hour. The rest was the same as in Example 1.

[0044] Example 4 The difference between this embodiment and Embodiment 1 is that it demonstrates the use of heat-resistant agents with different metal ion coordination, without the use of phenyl vinyl silicone oil.

[0045] (1) Preparation of heat resistant agent: The steps are the same as in Example 1, but zinc nitrate hexahydrate is replaced with an equimolar amount of copper nitrate, and the modified heat resistant agent L-Si-Cu hybrid is finally obtained.

[0046] (2) Preparation of thermal grease: Raw materials: 12 parts by mass of vinyl silicone oil (vinyl content 1.1%, viscosity 10000 mPa·s), 2 parts by mass of methyl phenyl silicone oil (phenyl content 10%, viscosity 400 mPa·s), 5 parts by mass of hydrogen-terminated silicone oil (hydrogen content 0.5%, viscosity 600 mPa·s), 3 parts by mass of platinum catalyst, 1 part by mass of inhibitor, 1 part by mass of silane coupling agent (KH-550), and 3 parts by mass of L-Si-Al hybrid heat resistant agent prepared in step (1). The thermally conductive filler is: 72 parts by mass of aluminum powder with an average particle size D50=15μm, 15 parts by mass of aluminum nitride with an average particle size D50=15μm, 12 parts by mass of α-alumina with an average particle size D50=10μm, 10 parts by mass of zinc oxide with an average particle size D50=5μm, and 3 parts by mass of cerium oxide.

[0047] The preparation steps are the same as in Example 1, except that the planetary stirring temperature in step b) is 100°C.

[0048] Example 5 The difference between this embodiment and Embodiment 1 is that it shows a filler combination that does not contain boron nitride, and the heat resistant agent uses different nitrogen-containing heterocycles.

[0049] (1) Preparation of heat resistant agent: Replace 3-amino-1,2,4-triazole in the step of Example 1 with an equimolar amount of 3-amino-1,2,3-triazole, and keep the other steps unchanged to obtain the heat resistant agent Triazole-Si-Zn.

[0050] (2) Preparation of thermal grease: Raw materials: 8 parts by mass of vinyl silicone oil (vinyl content 0.8%, viscosity 5000 mPa·s), 6 parts by mass of phenyl vinyl silicone oil (vinyl content 0.8%, phenyl content 18%, viscosity 6000 mPa·s), 4 parts by mass of methyl phenyl silicone oil (phenyl content 20%, viscosity 100 mPa·s), 4 parts by mass of hydrogen-terminated silicone oil (hydrogen content 0.3%, viscosity 800 mPa·s), 2 parts by mass of platinum catalyst, 2 parts by mass of inhibitor, 1.5 parts by mass of silane coupling agent (KH-560), and 4 parts by mass of heat-resistant agent Triazole-Si-Zn prepared in step (1). The thermally conductive fillers are: 73 parts by mass of aluminum powder with an average particle size D50=8μm, 18 parts by mass of aluminum nitride with an average particle size D50=8μm, 13 parts by mass of α-alumina with an average particle size D50=8μm, 8 parts by mass of zinc oxide with an average particle size D50=2μm, and 4 parts by mass of cerium oxide.

[0051] The preparation steps are the same as in Example 1, except that the curing time in step c) is 2 hours.

[0052] Example 6 The difference between this embodiment and Embodiment 1 is that all fillers use a single type of aluminum nitride to demonstrate its application in a specific high thermal conductivity filler system.

[0053] Raw materials: 15 parts by weight of vinyl silicone oil (vinyl content 0.6%, viscosity 3000 mPa·s), 7 parts by weight of phenyl vinyl silicone oil (vinyl content 0.4%, phenyl content 12%, viscosity 120 mPa·s), 3 parts by weight of methyl phenyl silicone oil (phenyl content 10%, viscosity 2000 mPa·s), 5 parts by weight of hydrogen-terminated silicone oil (hydrogen content 0.6%, viscosity 400 mPa·s), 4 parts by weight of platinum catalyst, 1 part by weight of inhibitor, 1 part by weight of silane coupling agent (KH-560), and 3 parts by weight of modified heat-resistant agent (prepared in the same way as in Example 1). The thermally conductive filler is: 110 parts by weight of spherical aluminum nitride with an average particle size D50 = 45 μm and 2 parts by weight of cerium oxide.

[0054] In preparation step a), only aluminum nitride and cerium oxide were pretreated. In step b), the planetary stirring speed was 15 Hz and the temperature was 90°C. The rest was the same as in Example 1.

[0055] Comparative Example 1 This comparative example simulates traditional physical hybrid thermal grease, without using an addition reaction curing system or special heat-resistant agents.

[0056] Raw materials: 20 parts by weight of dimethyl silicone oil (viscosity 1000 mPa·s), 2 parts by weight of fumed silica (thickener), and 1 part by weight of silane coupling agent (KH-560). Thermally conductive fillers: 70 parts by weight of aluminum powder with an average particle size D50 = 10 μm, 10 parts by weight of aluminum nitride with an average particle size D50 = 10 μm, 11 parts by weight of α-alumina with an average particle size D50 = 5 μm, 5 parts by weight of zinc oxide with an average particle size D50 = 0.2 μm, and 2 parts by weight of cerium oxide.

[0057] Preparation steps: Add all thermally conductive fillers, cerium oxide, and silane coupling agent to a powder modifier and stir at 90℃ and 1500 r / min for 1 hour. Add the modified fillers, dimethyl silicone oil, and fumed silica to a planetary mixer and stir at 120℃, vacuum degree -0.095 MPa, and 25 Hz for 2 hours (scraping every 15 minutes during the process) to obtain a paste-like physically mixed thermally conductive grease.

[0058] Comparative Example 2 This comparative example is based on Example 1, except that the modified heat-resistant agent (L-Si-Zn hybrid) is not used, and an equal amount of ordinary silane coupling agent KH-560 is used instead. The remaining components and preparation process are exactly the same as in Example 1.

[0059] Comparative Example 3 This comparative example is based on Example 1, but the addition reaction curing system is omitted. Vinyl silicone oil, phenyl vinyl silicone oil, and hydrogen-containing silicone oil are replaced with an equal total proportion of non-reactive methyl vinyl silicone oil of similar viscosity, and the platinum catalyst and inhibitor are removed. That is, the system is a physical mixture, but the filler composition and pretreatment are the same as in Example 1. During preparation, all raw materials (excluding the platinum catalyst and inhibitor) are added to the planetary mixer at once and mixed under the conditions of step b) in Example 1, without performing the heating curing step c).

[0060] Performance Testing and Result Analysis The samples obtained in Examples 1-6 and Comparative Examples 1-3 were subjected to performance tests. Thermal resistance testing was performed according to ASTM D5470 standard. Long-term reliability testing included: 1000 hours of high-temperature aging at 150°C, 1000 hours of dual 85°C (85°C / 85%RH) aging, and 1000 cycles of temperature shock from -40°C to 150°C (30-minute cycle). Thermal resistance was measured again after each test, and the rate of change of thermal resistance was calculated. Simultaneously, the coverage of the samples in the simulated chip package interface was observed and calculated using a scanning acoustic microscope (SAT). The results are shown in the table below:

[0061] Results Analysis: As shown in the table, the thermal greases provided in Examples 1-6 of this invention all exhibit extremely low initial thermal resistance (≤0.045℃·cm). 2 It boasts excellent long-term reliability (thermal resistance change rate <10% after three aging tests), and SAT interface coverage is higher than 89%, demonstrating outstanding overall performance.

[0062] Comparative Example 1 (traditional physical hybrid system) has high initial thermal resistance and its performance degrades severely after various aging tests, with a huge increase in thermal resistance and low interface coverage, which proves the fundamental defects of the physical hybrid system in terms of long-term reliability.

[0063] Although the initial thermal resistance of Comparative Example 2 (without heat resistant agent) was similar to that of Example 1, the thermal resistance increased significantly (>18%) after aging, proving that the specific modified heat resistant hybrid plays an irreplaceable key role in maintaining long-term thermal stability, and ordinary silane coupling agents cannot achieve the same effect.

[0064] The test results of Comparative Example 3 (cured without addition reaction) were similar to those of Comparative Example 1. It had high initial thermal resistance and severe performance degradation after aging. This proves that simply modifying the filler surface without building a chemical cross-linking network cannot solve the problems of system stability and long-term anti-aging under high filler filling.

[0065] In summary, this invention, by employing an addition reaction curing system to construct a three-dimensional network, filling it with an ultra-high proportion of surface-modified thermally conductive fillers, and introducing specific heat-resistant hybrids for synergistic effects, successfully obtains a thermally conductive silicone grease that combines ultra-low thermal resistance, high interface coverage, and excellent long-term reliability, effectively solving the heat dissipation problem of high-power-density semiconductor packaging. The above embodiments are merely examples; those skilled in the art can make other adjustments within the scope of the claims, and these adjustments should also be considered to fall within the protection scope of this invention.

Claims

1. A high-reliability thermal grease for semiconductor packaging, characterized in that, It is made by curing an addition reaction of a mixture containing the following components: Silicone oil systems include vinyl silicone oils and hydrogen-containing silicone oils that can undergo addition reactions; Thermally conductive filler, the total mass of which accounts for more than 90% of the total mass of the thermally conductive silicone grease; Platinum catalyst; as well as The heat resistant agent is an organic heat-resistant hybrid formed by modifying a silane coupling agent and introducing metal ions for coordination.

2. The thermal grease according to claim 1, characterized in that, The thermally conductive filler comprises at least one of metal powder and ceramic powder.

3. The thermal grease according to claim 2, characterized in that, By weight, the thermal grease comprises the following components: 4-18 parts vinyl silicone oil, 3-8 parts hydrogen-containing silicone oil, 90-110 parts thermally conductive filler, 1-5 parts heat-resistant agent, 1-2 parts silane coupling agent, and 1-5 parts platinum catalyst. The thermally conductive filler comprises at least three of the following: aluminum powder, aluminum nitride, aluminum oxide, zinc oxide, and boron nitride.

4. The thermal grease according to claim 3, characterized in that, The silicone oil system further includes phenyl vinyl silicone oil; and / or, methyl phenyl silicone oil.

5. The thermal grease according to claim 1 or 3, characterized in that, The average particle size D50 of the thermally conductive filler is less than 45 μm.

6. The thermal grease according to claim 1, characterized in that, The organic heat-resistant hybrid is formed by reacting a nitrogen-containing heterocyclic compound with a silane coupling agent, followed by coordination with metal ions.

7. The thermal grease according to claim 6, characterized in that, The nitrogen-containing heterocyclic compound is 3-amino-1,2,4-triazole, the silane coupling agent is chloropropyltriethoxysilane, and the metal ion is zinc ion.

8. A method for preparing a high-reliability thermal grease for semiconductor packaging as described in any one of claims 1-7, characterized in that, Includes the following steps: S1. Filler pretreatment: The thermally conductive filler is mixed with the heat-resistant agent and silane coupling agent, and then subjected to high-speed stirring and ball milling to obtain a surface-modified composite thermally conductive filler; S2. Mixing and dispersing: The silicone oil system and the composite thermally conductive filler obtained in step S1 are stirred and mixed under heating and vacuum conditions to obtain a uniform slurry; S3. Addition curing: A platinum catalyst is added to the slurry, and a curing reaction is carried out under vacuum and heating conditions to obtain the thermally conductive silicone grease.

9. The preparation method according to claim 8, characterized in that, In step S1, the high-speed stirring speed is 1000-2500 r / min, and the ball-to-material mass ratio of the ball mill is 3:

1. Step S2 is carried out in a planetary mixer at a stirring speed of 10-25 Hz, a mixing temperature of 80-120℃, and a vacuum degree of not less than -0.09 MPa. The curing temperature for step S3 is 80-100℃.

10. A heat dissipation interface for a semiconductor device, characterized in that, The thermal grease is obtained by curing the thermal grease prepared according to any one of claims 1-7 or according to any one of claims 8-10.

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