Raw materials, preparation method and application of low-volatility low-seepage heat-conducting gel for optical module

Abstract

The invention discloses raw materials, a preparation method and application of low-volatility low-seepage heat-conducting gel for an optical module, and relates to the technical field of heat-conducting gel for optical modules. The low-volatility low-exudation heat-conducting gel for the optical module is prepared from the following raw materials: side chain vinyl silicone oil, hydrogen-containing silicone oil, a coupling agent, a catalyst, an inhibitor, aluminum oxide A, aluminum oxide B, aluminum oxide C and boron nitride, wherein the aluminum oxide A is aluminum oxide with the particle size of 1-5 [mu] m, the aluminum oxide B is aluminum oxide with the particle size of 10-20 [mu] m, the aluminum oxide C is aluminum oxide with the particle size of 0.5-1 [mu] m, and the boron nitride is flaky boron nitride with the particle size of 50-100 nm. The flaky boron nitride and aluminum oxide with various particle sizes are adopted to synergistically construct a heat conduction network, the crosslinking density is optimized through the proportion of the side chain vinyl silicone oil to the hydrogen-containing silicone oil, the heat conduction gel with high heat conduction, low volatilization, low seepage and long-term stability is prepared, and the long-term reliable heat dissipation management requirement of a 5G / data center optical module can be met.

Description

Technical Field

[0001] This invention relates to the field of thermal conductive gel technology for optical modules, and particularly to the raw materials, preparation method and application of a low-volatility, low-exudation thermal conductive gel for optical modules. Background Technology

[0002] With the rapid development of 5G communication, data centers, and artificial intelligence technologies, high-speed optical modules are widely used in communication systems. These modules integrate high-power laser chips (such as EML and DFB), photodetectors, and precision optical components, generating significant heat during operation. Therefore, efficient thermally conductive materials are essential for rapid heat dissipation. Thermally conductive gels, as key thermal interface materials, are widely used to fill the space between the chip and the heat sink, reducing interfacial thermal resistance and improving heat dissipation efficiency.

[0003] Currently, traditional silicone thermal conductive gels exhibit a series of reliability problems when operating in high temperature and high humidity environments (such as 85℃ / 85%RH) for a long time, which seriously restricts the performance and lifespan of optical modules: (1) Silicone oil volatilization problem is prominent: Most addition-type silicone gels release low molecular weight cyclic siloxanes during the curing process or under long-term thermal aging conditions. When the material is heated at 150℃ for 24 hours, the mass loss (i.e., volatile matter) will exceed 0.1%. These volatile substances are very easy to condense and deposit in low temperature areas (such as optical lenses, fiber end faces or laser windows). (1) Forming non-volatile residues, contaminating optical lenses and circuits, leading to optical path attenuation and signal distortion; (2) High silicone oil seepage (oil seepage rate > 1.5%) problem: In traditional thermal conductive gels, the interface compatibility between the matrix silicone oil and the filler is poor, or the cross-linked network is not dense enough. Under high temperature conditions, silicone oil migration is likely to occur, leading to "oil separation" or "seepage". After the silicone oil migrates to the surface of the component, it will reduce the heat dissipation efficiency and accelerate aging; (3) Poor mechanical stability: It is easy to pulverize and crack after thermal shock, leading to interruption of the heat conduction path, significant increase in thermal resistance, and in severe cases, overheating damage to the chip.

[0004] Existing thermally conductive gels still have significant shortcomings in terms of low volatility, anti-leakage, and thermomechanical stability, making it difficult to meet the urgent needs of high-speed, high-density, and long-life optical modules for highly reliable thermal interface materials. Therefore, there is an urgent need to develop a novel thermally conductive gel that combines ultra-low volatility, no leakage, high thermal conductivity, and excellent thermal stability to improve the operational reliability and lifespan of optical modules under harsh operating conditions. Summary of the Invention

[0005] The main objective of this invention is to propose a raw material, preparation method, and application of a low-volatility, low-exudation thermally conductive gel for optical modules, aiming to solve the problem that existing thermally conductive gels cannot simultaneously achieve low volatility, low exudation, high thermal conductivity, and stability.

[0006] To achieve the above objectives, this invention proposes a raw material for a low-volatility, low-exudation thermally conductive gel for optical modules, comprising the following components by weight: 100 parts of side-chain vinyl silicone oil, 3-8 parts of hydrogen-containing silicone oil, 2-8 parts of coupling agent, 0.2-2 parts of catalyst, 0.4-4 parts of inhibitor, 400-600 parts of alumina A, 750-1000 parts of alumina B, 350-500 parts of alumina C, and 50-150 parts of boron nitride; Wherein, the alumina A is alumina with a particle size of 1~5μm, the alumina B is alumina with a particle size of 10~20μm, the alumina C is alumina with a particle size of 0.5~1μm, and the boron nitride is plate-shaped boron nitride with a particle size of 50~100nm.

[0007] In one embodiment, the side-chain vinyl silicone oil has a viscosity of 10,000~30,000 cSt at 25°C; and / or, The molecular weight of the side-chain vinyl silicone oil is 40,000 to 60,000; and / or, The hydrogen-containing silicone oil contains at least three Si-H functional groups; and / or, The molar ratio of the active groups in the hydrogen-containing silicone oil to the active groups in the vinyl silicone oil is (1.05~1.15):1.

[0008] In one embodiment, the raw material for the low-volatility, low-exudation thermally conductive gel for the optical module further includes 10 to 20 parts of 1-butyl-3-methylimidazolium hexafluorophosphate.

[0009] This invention proposes a method for preparing a low-volatility, low-percolation thermally conductive gel for optical modules, which is prepared using the raw materials of the aforementioned low-volatility, low-percolation thermally conductive gel for optical modules. The raw material for the low-volatility, low-exudation thermally conductive gel used in the optical module comprises, by weight, the following components: The composition comprises 100 parts of side-chain vinyl silicone oil, 3-8 parts of hydrogen-containing silicone oil, 2-8 parts of coupling agent, 0.2-2 parts of catalyst, 0.4-4 parts of inhibitor, 400-600 parts of alumina A, 750-1000 parts of alumina B, 350-500 parts of alumina C, and 50-150 parts of boron nitride; wherein, alumina A is alumina with a particle size of 1-5 μm, alumina B is alumina with a particle size of 10-20 μm, alumina C is alumina with a particle size of 0.5-1 μm, and boron nitride is plate-shaped boron nitride with a particle size of 50-100 nm. The preparation method of the low-volatility, low-exudation thermally conductive gel for the optical module includes the following steps: S10. Alumina A, alumina B, alumina C, and boron nitride are heated with a coupling agent under vacuum to perform surface modification treatment, thereby obtaining modified alumina A, modified alumina B, modified alumina C, and modified boron nitride. S20. The modified alumina A, modified alumina B, modified alumina C, modified boron nitride and side-chain vinyl silicone oil are mixed to obtain a first mixture; S30. The first mixture, hydrogen-containing silicone oil, catalyst and inhibitor are mixed and ground to make the maximum particle size of the powder in the system no greater than 10μm, to obtain the second mixture. Then the second mixture is degassed. S40. The degassed second mixture is pre-cured at 75~85℃ and then finally cured at 125~130℃ to obtain a low-volatility, low-exudation thermally conductive gel for optical modules.

[0010] In one embodiment, in step S10, aluminum oxide A, aluminum oxide B, aluminum oxide C, boron nitride, and coupling agent are heated under vacuum conditions at 110~120°C.

[0011] In one embodiment, in step S20, the modified alumina C and a portion of the side-chain vinyl silicone oil are first mixed, and then the modified alumina A, modified alumina B, and the remaining side-chain vinyl silicone oil are mixed to obtain a first mixture; and / or, Step S20 includes: mixing the modified alumina A, modified alumina B, modified alumina C, modified boron nitride, 1-butyl-3-methylimidazolium hexafluorophosphate and side-chain vinyl silicone oil, and degassing to obtain a first mixture.

[0012] In one embodiment, in step S30, the grinding includes grinding using a three-roll mill; The roller gap pressure is 10~15MPa, and the roller speed ratio is 1:3:9.

[0013] In one embodiment, in step S40, the pre-curing time is 1-2 hours; and / or, The final curing time is 1.5~2.5h.

[0014] This invention proposes a low-volatility, low-exudation thermally conductive gel for optical modules, which is prepared according to the preparation method of the low-volatility, low-exudation thermally conductive gel for optical modules described in the aforementioned technical solution.

[0015] This invention proposes the application of the low-volatility, low-exudation thermally conductive gel for optical modules described in the aforementioned technical solution in the preparation of high-speed optical modules.

[0016] This invention significantly improves the overall performance of organosilicon thermal conductive gel by optimizing the multi-scale gradation of thermally conductive filler powder and using plate-shaped boron nitride (BN) and alumina of various particle sizes to synergistically construct a highly efficient thermally conductive network. Large-particle-size alumina serves as a thermally conductive framework, providing long-distance heat conduction paths, effectively reducing interfacial thermal resistance, acting as the main heat conduction pathway, and occupying the majority of the volume. Medium / small-particle-size alumina fills the gaps between large particles, increasing the overall filler packing density and reducing the volume fraction of the polymer matrix. This not only further refines the heat conduction path and enhances the connectivity of the heat conduction network but also reduces porosity from the source, decreasing the content of migratable low-molecular-weight silicone oil, which helps suppress exudation. Plate-like boron nitride has extremely high in-plane thermal conductivity, far exceeding that of alumina. During the preparation process, plate-like BN easily forms parallel arrangements in the matrix under shear force, forming a highly efficient in-plane thermal conduction network, significantly improving the thermal conductivity of the material in the vertical direction (i.e., the heat dissipation direction). At the same time, the BN plates have a high aspect ratio, uniformly dispersed in the matrix like countless "shields," greatly increasing the tortuosity of the migration path of small-molecule silicone oil, forcing migrating molecules to detour, significantly extending the diffusion path, reducing the migration rate, and thus effectively reducing the oil seepage rate. Furthermore, this invention selects side-chain vinyl silicone oil as the main resin, which facilitates the optimization of the crosslinking density of the hydrosilylation reaction by controlling the ratio of side-chain vinyl silicone oil to hydrogen-containing silicone oil, thereby obtaining a three-dimensional network structure with high crosslinking density. This further reduces the volatilization and exudation behavior of the material under high temperature and high humidity environments, while improving the thermal stability and mechanical durability of the material. Using the raw materials provided by this invention, a thermally conductive gel with a thermal conductivity greater than 6.0 W / mK, an oil permeation rate of less than 0.5%, and a volatile content of less than 0.1% can be prepared. This material combines high thermal conductivity, low volatility, low exudation, and long-term stability, and can be applied to the long-term reliable heat dissipation management of 5G / data center optical modules, effectively solving the problem that existing thermally conductive gels cannot simultaneously achieve low volatility, low exudation, high thermal conductivity, and stability. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0018] Figure 1 This is a powder gradation filling model diagram for the low-volatility, low-exudation thermally conductive gel used in optical modules provided by the present invention.

[0019] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0022] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0023] Traditional silicone thermal conductive gels have the following problems when operating in high temperature and high humidity environments (such as 85℃ / 85%RH) for a long time: (1) Silicone oil volatilization is prominent: Most addition-type silicone gels release low molecular weight cyclic siloxanes during the curing process or under long-term thermal aging conditions. When the material is heated at 150℃ for 24 hours, the mass loss (i.e., volatile matter) will exceed 0.1%. These volatile substances are very easy to condense and deposit in low temperature areas (such as optical lenses, fiber end faces or laser windows), forming non-volatile residues and contamination. (1) The coating on optical lenses and circuits causes optical path attenuation and signal distortion; (2) High silicone oil leakage (oil leakage rate > 1.5%) problem: In traditional thermal conductive gels, the interface compatibility between the matrix silicone oil and the filler is poor, or the cross-linked network is not dense enough. Under high temperature conditions, silicone oil migration is likely to occur, resulting in "oil separation" or "exudation". After the silicone oil migrates to the surface of the component, it will reduce the heat dissipation efficiency and accelerate aging; (3) Poor mechanical stability: It is easy to pulverize and crack after thermal shock, resulting in interruption of the heat conduction path, significant increase in thermal resistance, and in severe cases, overheating damage to the chip. Therefore, it is urgent to develop a new type of thermal conductive gel with ultra-low volatility, no leakage, high thermal conductivity and excellent thermal stability to improve the operational reliability and service life of optical modules under harsh conditions.

[0024] In view of this, the present invention proposes a raw material for a low-volatility, low-exudation thermally conductive gel for optical modules, comprising the following components by weight: 100 parts of side-chain vinyl silicone oil, 3-8 parts of hydrogen-containing silicone oil, 2-8 parts of coupling agent, 0.2-2 parts of catalyst, 0.4-4 parts of inhibitor, 400-600 parts of alumina A, 750-1000 parts of alumina B, 350-500 parts of alumina C, and 50-150 parts of boron nitride; Wherein, the alumina A is alumina with a particle size of 1~5μm, the alumina B is alumina with a particle size of 10~20μm, the alumina C is alumina with a particle size of 0.5~1μm, and the boron nitride is plate-shaped boron nitride with a particle size of 50~100nm.

[0025] This invention significantly improves the overall performance of organosilicon thermally conductive gels by optimizing the multi-scale gradation of thermally conductive filler powder and synergistically constructing a highly efficient thermally conductive network using plate-like boron nitride (BN) and alumina of various particle sizes. The powder gradation and filling model diagram is shown below. Figure 1As shown, large-particle-size alumina (10~20μm) serves as a thermally conductive framework, providing long-distance heat conduction paths, effectively reducing interfacial thermal resistance, acting as the main heat conduction pathway, and occupying the majority of the volume. Medium / small-particle-size alumina (1~5μm and 0.5~1μm) fills the voids between large particles, increasing the overall filler packing density and reducing the volume fraction of the polymer matrix. This not only further refines the heat conduction path and enhances the connectivity of the heat conduction network but also reduces porosity at the source, lowering the absolute content of migratable low-molecular-weight silicone oil, which helps suppress exudation. Plate-like boron nitride has extremely high surface area... The internal thermal conductivity (~300~600 W / mK) is much higher than that of alumina (~30 W / mK). During the preparation process, the sheet-like BN easily forms parallel arrangements in the matrix under shear force, forming a highly efficient in-plane thermally conductive network, which significantly improves the thermal conductivity of the material in the vertical direction (i.e., the heat dissipation direction). At the same time, the BN sheets have a high aspect ratio (high longitudinal-to-transverse ratio), which is uniformly dispersed in the matrix like countless "shields", greatly increasing the tortuosity of the migration path of small molecule silicone oil, forcing the migrating molecules to detour, significantly lengthening the diffusion path and reducing the migration rate, thereby effectively reducing the oil leakage rate. In addition, this invention selects side-chain vinyl silicone oil as the main resin, and optimizes the crosslinking density of the hydrosilylation reaction by controlling the ratio of side-chain vinyl silicone oil and hydrogen-containing silicone oil, which is beneficial to obtaining a three-dimensional network structure with high crosslinking density, further reducing the volatilization and exudation behavior of the material under high temperature and high humidity environment, while improving the thermal stability and mechanical durability of the material. Using the raw materials provided by this invention, a thermally conductive gel with a thermal conductivity greater than 6.0 W / mK, an oil permeation rate of less than 0.5%, and a volatile content of less than 0.1% can be prepared. This material combines high thermal conductivity, low volatility, low permeation, and long-term stability, and can be applied to the long-term reliable heat dissipation management of 5G / data center optical modules, effectively solving the problem that existing thermally conductive gels cannot simultaneously achieve low volatility, low permeation, high thermal conductivity, and stability.

[0026] It should be noted that, compared with silicone oils that contain vinyl groups only at the ends of the molecular chain (i.e., terminal vinyl silicone oils), side-chain vinyl silicone oils also have multiple vinyl groups distributed on the main chain. When vinyl silicone oils undergo addition reactions with hydrogen-containing silicone oils, the side-chain vinyl groups have more vinyl groups participating in the reaction, thus providing more crosslinking point possibilities. This helps to form a denser crosslinking network, effectively inhibiting the migration of small molecules and obtaining a thermally conductive gel with low volatility and low exudation.

[0027] In embodiments of the present invention, the viscosity of the side-chain vinyl silicone oil at 25°C is 10,000~30,000 cSt. Using a vinyl silicone oil with a viscosity of 10,000~30,000 cSt as the main component results in lower migration, effectively reducing the possibility of volatilization and exudation. It also avoids the problems of excessively high viscosity, which can lead to uneven dispersion of the vinyl silicone oil with other raw materials (such as thermally conductive fillers) and hinder bubble removal.

[0028] In embodiments of the present invention, the molecular weight of the side-chain vinyl silicone oil is 40,000 to 60,000. Using vinyl silicone oils with molecular weights within this range results in higher molecular weights and narrower molecular weight distributions. Higher molecular weight vinyl silicone oils correspond to longer vinyl silicone oil backbones. After addition reactions with hydrogen-containing crosslinking agents, the resulting crosslinking network nodes have longer "segments" that are more easily entangled, enhancing the stability of the crosslinking network and suppressing the volatilization and exudation of small molecule siloxanes. Using vinyl silicone oils with narrow molecular weight distributions facilitates the formation of a uniform and regular three-dimensional crosslinking network structure, further reducing volatilization and exudation.

[0029] In embodiments of the present invention, the hydrogen-containing silicone oil contains at least three Si-H functional groups. Using hydrogen-containing silicone oils containing three or more Si-H groups (such as "T-type" hydrogen-containing silicone oils containing ≡Si-H structures) can significantly increase the crosslinking point density, form a tighter network, and more effectively bind linear segments, thereby significantly reducing volatilization and exudation.

[0030] In embodiments of the present invention, the molar ratio of the active groups in the hydrogen-containing silicone oil to the active groups in the vinyl silicone oil is (1.05~1.15):1. In this invention, the active groups in the hydrogen-containing silicone oil refer to Si-H groups (silicon-hydrogen bonds), and the active groups in the vinyl silicone oil refer to Si-CH=CH2 groups (i.e., vinyl groups). Excessive Si-H groups ensure that the vinyl groups react as completely as possible, reducing the amount of unreacted vinyl silicone oil (usually the larger molecular weight component). However, too many Si-H groups can lead to residual Si-H groups, which are unstable (potentially slowly hydrolyzing to produce hydrogen or silanols), resulting in decreased stability of the entire system. Therefore, this invention strictly controls the molar ratio of the active groups in the hydrogen-containing silicone oil to the active groups in the vinyl silicone oil, setting the amount of active groups in the hydrogen-containing silicone oil to be slightly more than that in the vinyl silicone oil.

[0031] In embodiments of the present invention, the silane coupling agent comprises an aminosilane coupling agent. In one embodiment of the present invention, 3-aminopropyltriethoxysilane (KH-550) is used to modify the thermally conductive filler.

[0032] In embodiments of the present invention, the catalyst comprises a platinum catalyst. The catalyst is used to catalyze the hydrosilylation reaction between Si-H in hydrogen-containing silicone oil and vinyl groups (Vi-CH=CH2) in ethylene silicone oil.

[0033] In embodiments of the present invention, the inhibitor comprises ethynylcyclohexanol.

[0034] In an embodiment of the present invention, the raw material for the low-volatility, low-exudation thermally conductive gel of the optical module further includes 10-20 parts of 1-butyl-3-methylimidazolium hexafluorophosphate. The addition of a small amount of 1-butyl-3-methylimidazolium hexafluorophosphate, along with the addition of cations in the ionic liquid (BMIM), further enhances its properties. + ) or anion (PF6) - By adsorbing onto the surface of BN particles through electrostatics, van der Waals forces, or dipole interactions, the surface properties of BN are adjusted and optimized, reducing the interactions between BN particles. This helps improve the dispersibility of BN, facilitates the orientation of BN, and is conducive to building a more efficient in-plane thermal conductivity network. It significantly improves the thermal conductivity in the vertical direction (usually the heat dissipation direction). At the same time, it also enables BN to be better compatible and dispersed with silicone oil, reducing interface defects (weak boundary layers). Since interface defects are often the preferred channels for oil seepage, it also helps to improve the resistance to oil seepage.

[0035] This invention proposes a method for preparing a low-volatility, low-exudation thermally conductive gel for optical modules. The method utilizes the raw materials for this gel, which, by weight, comprises the following components: The composition comprises 100 parts of side-chain vinyl silicone oil, 3-8 parts of hydrogen-containing silicone oil, 2-8 parts of coupling agent, 0.2-2 parts of catalyst, 0.4-4 parts of inhibitor, 400-600 parts of alumina A, 750-1000 parts of alumina B, 350-500 parts of alumina C, and 50-150 parts of boron nitride; wherein, alumina A is alumina with a particle size of 1-5 μm, alumina B is alumina with a particle size of 10-20 μm, alumina C is alumina with a particle size of 0.5-1 μm, and boron nitride is plate-shaped boron nitride with a particle size of 50-100 nm. The preparation method of the low-volatility, low-exudation thermally conductive gel for the optical module includes the following steps: S10. Alumina A, alumina B, alumina C, and boron nitride are heated with a coupling agent under vacuum to perform surface modification treatment, thereby obtaining modified alumina A, modified alumina B, modified alumina C, and modified boron nitride. S20. The modified alumina A, modified alumina B, modified alumina C, modified boron nitride and side-chain vinyl silicone oil are mixed to obtain a first mixture; S30. The first mixture, hydrogen-containing silicone oil, catalyst and inhibitor are mixed and ground to make the maximum particle size of the powder in the system no greater than 10μm, to obtain the second mixture. Then the second mixture is degassed. S40. The degassed second mixture is pre-cured at 75~85℃ and then finally cured at 125~130℃ to obtain a low-volatility, low-exudation thermally conductive gel for optical modules.

[0036] In the technical solution of this invention, the thermally conductive fillers (alumina and boron nitride) are first modified with coupling agents to improve the interfacial compatibility between the fillers and the organosilicon matrix. Then, the modified thermally conductive fillers and side-chain vinyl silicone oil are premixed to form a stable and uniform "masterbatch" that fully wets the fillers. Next, hydrogen-containing silicone oil, a catalyst, and an inhibitor are added, and the thermally conductive fillers are further refined and dispersed through three-roll milling. Finally, the mixed raw materials are cured in stages, first by preliminary heating and then by further heating and curing. After preliminary curing, a small number of active groups or groups in unfavorable reaction positions may still remain in the system. Appropriate post-curing at this point can promote these residual reactions and further increase the crosslinking density. Using the technical solution of this invention, the thermally conductive fillers can be highly dispersed and well-oriented, which is beneficial for constructing efficient thermally conductive pathways and obtaining a crosslinked network structure with high crosslinking density and good uniformity. This is beneficial for preparing thermally conductive gels with low volatility, low exudation, and high thermal conductivity.

[0037] In an embodiment of the present invention, in step S10, alumina A, alumina B, alumina C, and boron nitride are heated with a coupling agent under vacuum conditions of 110-120°C. Within this range, the heating temperature under vacuum conditions can be 110°C, 115°C, or 120°C. Specifically, the coupling agent and water are first mixed to form a coupling agent solution, and then the coupling agent solution is mixed with a thermally conductive filler (alumina or boron nitride) and heated under vacuum conditions of 110-120°C.

[0038] In an embodiment of the present invention, in step S10, the masses of alumina A, alumina B, alumina C, and boron nitride are m1, m2, m3, and m4, respectively; the total amount of coupling agent is M; the amount of coupling agent reacting with alumina A is M1; the amount of coupling agent reacting with alumina B is M2; the amount of coupling agent reacting with alumina C is M3; and the amount of coupling agent reacting with boron nitride is M4. M1 = m1 * M / (m1 + m2 + m3 + m4); M2 = m2 * M / (m1 + m2 + m3 + m4); M3 = m3 * M / (m1 + m2 + m3 + m4); M4 = m4 * M / (m1 + m2 + m3 + m4); M = M1 + M2 + M3 + M4.

[0039] In an embodiment of the present invention, in step S20, the modified alumina C and a portion of the side-chain vinyl silicone oil are first mixed, and then the modified alumina A, modified alumina B and the remaining side-chain vinyl silicone oil are mixed to obtain a first mixture.

[0040] First, small-particle-size fillers modified with silane coupling agents are premixed with a portion of the silicone oil matrix. High shear force is used to ensure sufficient dispersion and prevent agglomeration. Then, medium-particle-size fillers modified with silane coupling agents, large-particle-size fillers modified with silane coupling agents, and the remaining silicone oil, crosslinking agent, catalyst, and inhibitor are gradually added. This arrangement helps ensure component uniformity, resulting in highly dispersed and well-oriented thermally conductive fillers, leading to a low-volatility, low-exudation, and high-thermal-conductivity thermally conductive gel.

[0041] In an embodiment of the present invention, step S20 includes: mixing the modified alumina A, modified alumina B, modified alumina C, modified boron nitride, 1-butyl-3-methylimidazolium hexafluorophosphate and vinyl silicone oil, and degassing to obtain a first mixture.

[0042] When modified boron nitride is added, a small amount of 1-butyl-3-methylimidazolium hexafluorophosphate is also added, which is used to ionize the cations in the ionic liquid (BMIM). + ) or anion (PF6) - By adsorbing onto the surface of BN particles through electrostatics, van der Waals forces, or dipole interactions, the surface properties of BN can be adjusted and optimized, reducing the interaction between BN particles, thereby improving the dispersibility of BN and facilitating the orientation alignment of BN.

[0043] In an embodiment of the present invention, step S30 includes grinding using a three-roll mill; The roller gap pressure is 10~15MPa, and the roller speed ratio is 1:3:9.

[0044] Setting the parameters of the three-roll mill within the above range ensures that the thermally conductive filler is not broken and has good dispersion.

[0045] In an embodiment of the present invention, step S30, the degassing treatment includes degassing using a planetary agitator. The degassing temperature is 45°C, and the degassing time is 2 hours.

[0046] In an embodiment of the present invention, in step S40, the pre-curing time is 1-2 hours. The pre-curing time is set near the point where the viscosity begins to rise but has not yet fully gelled. If the pre-curing time is too long, complete gelation will occur, making further curing impossible; if the pre-curing time is too short, the viscosity will not rise sufficiently, and oil seepage may occur subsequently.

[0047] In an embodiment of the present invention, in step S40, the final curing time is 1.5 to 2.5 hours. The purpose of final curing is to maximize and stabilize the material properties. At a curing temperature of 125 to 130°C, if the curing time is too long, the hardness may increase and a gel may not form; if the curing time is too short, the curing may be incomplete, and oil seepage may occur subsequently.

[0048] This invention proposes a low-volatility, low-percolation thermally conductive gel for optical modules, which is prepared according to the preparation method of the low-volatility, low-percolation thermally conductive gel for optical modules described in the aforementioned technical solution.

[0049] This invention proposes the application of the low-volatility, low-exudation thermally conductive gel for optical modules described in the aforementioned technical solution in the fabrication of high-speed optical modules. The high-speed optical module incorporates all the technical solutions described in the low-volatility, low-exudation thermally conductive gel for optical modules, and therefore possesses all the beneficial effects of the gel, which will not be elaborated upon here.

[0050] The technical solution of the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be understood that the following embodiments are only used to explain the present invention and are not intended to limit the present invention.

[0051] In the following embodiments, the side-chain vinyl silicone oil was purchased from Shenzhen Jipeng Silicon Fluorine Materials Co., Ltd., and its model number is JP5. The hydrogen-containing silicone oil is a type T hydrogen-containing silicone oil purchased from Shandong Huanzheng Chemical Co., Ltd., with model number 202 and molecular weight of 15000.

[0052] Example 1 A method for preparing a low-volatility, low-exudation thermally conductive gel for optical modules includes the following steps: (1) 500g of alumina A (3μm), 800g of alumina B (15μm), 400g of alumina C (0.8μm), and 100g of boron nitride (50nm) were heated with KH-550 solution at 120℃ under vacuum to perform surface modification treatment, resulting in modified alumina A, modified alumina B, modified alumina C and modified boron nitride; wherein, the total mass of KH-550 was 5g, and the KH-550 solution was prepared by mixing KH-550 and 10g of deionized water evenly and then adding 85g of ethanol; (2) The modified alumina A, modified alumina B, modified alumina C, modified boron nitride and 100g of side-chain vinyl silicone oil (viscosity 20000cSt, molecular weight 50000) obtained in step (1) are mixed to obtain the first mixture; (3) The first mixture from step (2), 5g of hydrogen-containing silicone oil, 0.5g of platinum catalyst and 2g of ethynylcyclohexanol are mixed and ground with a three-roll mill to make the maximum particle size of the powder in the system no greater than 8μm, to obtain the second mixture. Then the second mixture is degassed by a planetary stirrer (45℃, 2h). (4) The second mixture after degassing in step (3) is first pre-cured at 80°C for 1 hour, and then finally cured at 125°C for 2 hours to obtain a low-volatility, low-exudation thermally conductive gel for optical modules.

[0053] Example 2 The difference from Example 1 is that the mass ratio of alumina A, alumina B, and alumina C is 400:800:500.

[0054] Example 3 The difference compared to Example 1 is that the boron nitride particle size is 100 nm.

[0055] Example 4 Compared with Example 1, the difference is that 10g of 1-butyl-3-methylimidazolium hexafluorophosphate is added in step (2).

[0056] Example 5 Compared with Example 1, the difference is that 20g of 1-butyl-3-methylimidazolium hexafluorophosphate is added in step (2).

[0057] Example 6 Compared with Example 1, the difference is that 5g of 1-butyl-3-methylimidazolium hexafluorophosphate is added in step (2).

[0058] Example 7 The difference from Example 1 is that the vinyl silicone oil has a molecular weight of 40,000 and a viscosity of 10,000 cSt at 25°C.

[0059] Example 8 The difference from Example 1 is that the vinyl silicone oil has a molecular weight of 60,000 and a viscosity of 30,000 cSt at 25°C.

[0060] Example 9 Compared with Example 1, the difference is that the molar ratio of Si-H groups in the hydrogen-containing silicone oil and Si-CH=CH2 groups in the side-chain vinyl silicone oil is 1.05:1.

[0061] Example 10 Compared with Example 1, the difference is that the molar ratio of Si-H groups in the hydrogen-containing silicone oil and Si-CH=CH2 groups in the side-chain vinyl silicone oil is 1.15:1.

[0062] Example 11 Compared with Example 1, the difference is that in step (2), the modified alumina C and 50% of the side-chain vinyl silicone oil are mixed first, and then the modified alumina A, modified alumina B and the remaining side-chain vinyl silicone oil are mixed to obtain the first mixture.

[0063] Comparative Example 1 Compared with Example 1, the difference is that aluminum oxide B and aluminum oxide C are all replaced with aluminum oxide A.

[0064] Comparative Example 2 The difference from Example 1 is that boron nitride is replaced with an equal amount of aluminum oxide B.

[0065] Comparative Example 3 The difference compared to Example 1 is that the amount of hydrogen-containing silicone oil used is 2g.

[0066] Comparative Example 4 The difference compared to Example 1 is that the viscosity of the vinyl silicone oil at 25°C is 8000 cSt.

[0067] Comparative Example 5 Compared with Example 1, the difference is that in step (4), the degassed second mixture is directly cured at 125°C for 3 hours.

[0068] Comparative Example 6 The difference from Example 1 is that the mass ratio of alumina A, alumina B, and alumina C is 200:800:700.

[0069] Comparative Example 7 The difference compared to Example 1 is that the boron nitride particle size is 5 μm.

[0070] Performance testing 1. Thermal conductivity, volatile matter, oil penetration rate, and double 85 test: Thermal conductivity test: The sample size is 20*20*2mm, and the test is conducted according to ISO22007-2.2 standard.

[0071] Volatile matter test: The sample size is 20*20*2mm, and the test is conducted according to ASTM E595 standard.

[0072] Oil seepage rate test: The sample size is 20*20*2mm, and it is baked in an oven at 125℃ for 48h. The mass loss rate is calculated.

[0073] Double 85 test: The sample size is 20*20*2mm. It is placed in an environment of 85℃ / 85%RH for 1000h to determine whether the results are complete and whether powdering or cracking occurs.

[0074] The test results are shown in Table 1 below: Table 1. Performance test results of low-volatile, low-exudation thermally conductive gels for optical modules in Examples 1-11 and Comparative Examples 1-7, as well as commercially available products.

[0075] The following conclusions can be drawn from Table 1: (1) Based on the test results of Examples 1-2 and Comparative Example 6, it can be seen that when the mass ratio of alumina A / B / C exceeds (400~600):(750~1000):(350~500), the oil penetration rate will increase.

[0076] (2) Based on the test results of Example 1 and Comparative Examples 1-2, it can be seen that using alumina with a single particle size will increase the porosity of the thermal conductive gel. It is evident that using alumina with multiple particle sizes is the key to reducing porosity (Comparative Example 1). Using only alumina with multiple particle sizes without using boron nitride will also worsen the test results of thermal conductivity, volatile matter and oil permeability (Comparative Example 2).

[0077] (3) Combining the test results of Example 1, Example 3 and Comparative Example 7, it can be seen that when the particle size of BN is too large, it has little impact on the test results of volatile matter and oil penetration rate, but the thermal conductivity will deteriorate.

[0078] (4) Based on the test results of Examples 1 and 4-6, it can be seen that adding a small amount of ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate) is beneficial to further improve the thermal conductivity, reduce the volatile matter and oil penetration rate, and improve the overall performance of the prepared thermal conductive gel.

[0079] (5) Combining the test results of Examples 1 and 7-8, it can be seen that as the molecular weight and viscosity of vinyl silicone oil increase, the test results of thermal conductivity, volatile matter and oil penetration rate will deteriorate. Combining the test results of Example 1 and Comparative Example 4, it can be seen that when the viscosity of vinyl silicone oil is below 10000 cSt, the test results of thermal conductivity, volatile matter and oil penetration rate will deteriorate significantly, and cracks are more likely to occur.

[0080] (6) Combining the test results of Example 1 and Example 11, it can be seen that the thermal conductivity and volatile matter test results of Example 11 are better than those of Example 1, indicating that the stepwise feeding method of mixing small particle size filler and part of silicone oil first is beneficial to improving thermal conductivity and reducing volatilization.

[0081] (7) Combining the test results of Example 1 and Comparative Example 3, it can be seen that when the amount of hydrogen-containing silicone oil is too small, the crosslinking is insufficient, which will significantly worsen the test results of thermal conductivity, volatile matter and oil penetration rate.

[0082] (8) Combining the test results of Example 1 and Comparative Example 5, it can be seen that the test results of thermal conductivity, volatile matter and oil penetration rate of Example 1 are better than those of Comparative Example 5, and it is not easy to crack. This shows that the staged curing method can improve the thermal conductivity of the prepared thermal conductive gel, reduce volatilization and reduce oil penetration rate.

[0083] 2. Stability testing under extreme environments: To further verify the stability of the low-volatility, low-exudation thermally conductive gel for optical modules provided by the present invention under extreme environments, the following tests were also conducted, taking Example 1 as an example.

[0084] Breakdown voltage test: The test was conducted according to ASTM D149, "Test method for dielectric breakdown strength and dielectric strength of solid electrical insulating materials at power frequency voltage". The breakdown voltage of Example 1 was 12.3 kV / mm, which is much higher than that of conventional gels (5~8 kV / mm). The breakdown voltage of Comparative Example 2 was found to be lower than 12 kV / mm, indicating that the introduction of boron nitride is beneficial to improving the breakdown voltage of the thermally conductive gel and reducing the possibility of short circuits in the optical module.

[0085] Thermal shock test: After being placed at -40℃ for 1 hour, it was placed at 85℃ for 1 hour, and the cycle was repeated 1000 times. After 1000 thermal shock cycles, the structure of the low-volatility and low-exudation thermally conductive gel used in the optical module of Example 1 remained intact, with no failures.

[0086] High and low temperature cycling test: placed at -40℃ for 1 hour, then placed at 125℃ for 1 hour, 1000 cycles. After 1000 high and low temperature cycles, the structure of the low-volatility and low-exudation thermally conductive gel used in the optical module of Example 1 remained intact, with no failures.

[0087] 3. Compatibility testing in ultra-thin optical modules: To verify the suitability of the low-volatility, low-exudation thermal conductive gel for optical modules provided by this invention in ultra-thin optical modules, taking Example 1 as an example, the low-volatility, low-exudation thermal conductive gel for optical modules in Example 1 was made into a 0.3 mm thick thermal conductive gel sheet. The thermal conductivity was measured to be greater than 5.5 W / mK, which can meet the requirements for the use of thermal conductive gel in ultra-thin optical modules (thermal conductivity meets the requirement of ≥4.5 W / mK).

[0088] In summary, the low-volatility, low-exudation thermally conductive gel for optical modules provided by this invention has a thermal conductivity of 6.0~6.5 W / mK, volatile matter ≤0.1%, oil leakage rate <0.5%, and a thermal conductivity greater than 5.5 W / mK at a thickness of 0.3 mm. After 1000 hours of dual 85 testing, 1000 cycles of thermal shock, and 1000 cycles of high and low temperature cycling, it maintains structural integrity without cracking or failure. These results demonstrate that the low-volatility, low-exudation thermally conductive gel for optical modules provided by this invention possesses excellent ultra-high thermal conductivity, extremely low volatility, ultra-low oil leakage rate, compatibility with ultra-thin optical modules, and stability in extreme environments. It is suitable for long-term reliable heat dissipation of 5G / data center optical modules, effectively solving the problem that existing thermally conductive gels struggle to simultaneously achieve low volatility, low exudation, high thermal conductivity, and stability.

[0089] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A raw material for a low-volatility, low-exudation thermally conductive gel for optical modules, characterized in that, By weight, it includes the following components: 100 parts of side-chain vinyl silicone oil, 3-8 parts of hydrogen-containing silicone oil, 2-8 parts of coupling agent, 0.2-2 parts of catalyst, 0.4-4 parts of inhibitor, 400-600 parts of alumina A, 750-1000 parts of alumina B, 350-500 parts of alumina C, and 50-150 parts of boron nitride; Wherein, the alumina A is alumina with a particle size of 1~5μm, the alumina B is alumina with a particle size of 10~20μm, the alumina C is alumina with a particle size of 0.5~1μm, and the boron nitride is plate-shaped boron nitride with a particle size of 50~100nm.

2. The raw material of the low-volatility, low-exudation thermally conductive gel for optical modules as described in claim 1, characterized in that, The side-chain vinyl silicone oil has a viscosity of 10,000~30,000 cSt at 25°C; and / or, The molecular weight of the side-chain vinyl silicone oil is 40,000 to 60,000; and / or, The hydrogen-containing silicone oil contains at least three Si-H functional groups; and / or, The molar ratio of the active groups in the hydrogen-containing silicone oil to the active groups in the vinyl silicone oil is (1.05~1.15):

1.

3. The raw material of the low-volatility, low-exudation thermally conductive gel for optical modules as described in claim 1, characterized in that, It also includes 10 to 20 parts of 1-butyl-3-methylimidazolium hexafluorophosphate.

4. A method for preparing a low-volatility, low-exudation thermally conductive gel for optical modules, characterized in that, The low-volatility, low-exudation thermally conductive gel for optical modules is prepared using the raw materials of the low-volatility, low-exudation thermally conductive gel for optical modules according to any one of claims 1 to 3. The preparation method of the low-volatility, low-exudation thermally conductive gel for optical modules includes the following steps: S10. Alumina A, alumina B, alumina C, and boron nitride are heated with a coupling agent under vacuum to perform surface modification treatment, thereby obtaining modified alumina A, modified alumina B, modified alumina C, and modified boron nitride. S20. The modified alumina A, modified alumina B, modified alumina C, modified boron nitride and side-chain vinyl silicone oil are mixed to obtain a first mixture; S30. The first mixture, hydrogen-containing silicone oil, catalyst and inhibitor are mixed and ground to make the maximum particle size of the powder in the system no greater than 10μm, to obtain the second mixture. Then the second mixture is degassed. S40. The degassed second mixture is pre-cured at 75~85℃ and then finally cured at 125~130℃ to obtain a low-volatility, low-exudation thermally conductive gel for optical modules. Wherein, the alumina A is alumina with a particle size of 1~5μm, the alumina B is alumina with a particle size of 10~20μm, the alumina C is alumina with a particle size of 0.5~1μm, and the boron nitride is plate-shaped boron nitride with a particle size of 50~100nm.

5. The method for preparing the low-volatility, low-exudation thermally conductive gel for optical modules as described in claim 4, characterized in that, In step S10, aluminum oxide A, aluminum oxide B, aluminum oxide C, and boron nitride are heated with a coupling agent under vacuum conditions of 110~120°C.

6. The method for preparing the low-volatility, low-exudation thermally conductive gel for optical modules as described in claim 4, characterized in that, In step S20, the modified alumina C and a portion of the side-chain vinyl silicone oil are first mixed, and then the modified alumina A, modified alumina B and the remaining side-chain vinyl silicone oil are mixed to obtain a first mixture; And / or, Step S20 includes: mixing the modified alumina A, modified alumina B, modified alumina C, modified boron nitride, 1-butyl-3-methylimidazolium hexafluorophosphate and side-chain vinyl silicone oil to obtain a first mixture.

7. The method for preparing the low-volatility, low-exudation thermally conductive gel for optical modules as described in claim 4, characterized in that, In step S30, the grinding includes grinding using a three-roll mill; The roller gap pressure is 10~15MPa, and the roller speed ratio is 1:3:

9.

8. The method for preparing the low-volatility, low-exudation thermally conductive gel for optical modules as described in claim 4, characterized in that, In step S40, the pre-curing time is 1-2 hours; and / or, The final curing time is 1.5~2.5h.

9. A low-volatility, low-exudation thermally conductive gel for optical modules, characterized in that, The optical module is prepared using a low-volatility, low-exudation thermally conductive gel according to any one of claims 4 to 8.

10. The application of the low-volatility, low-exudation thermally conductive gel for optical modules as described in claim 9 in the fabrication of high-speed optical modules.

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