High-thermal-conductivity ceramic material for LED packaging and manufacturing process of high-thermal-conductivity ceramic material

Abstract

The invention belongs to the field of electronic packaging materials, and particularly relates to a high-thermal-conductivity ceramic material for LED packaging and a manufacturing process of the high-thermal-conductivity ceramic material for LED packaging. The high-thermal-conductivity ceramic material is prepared from silicon nitride, aluminum nitride, magnesium fluoride, yttrium fluoride, lithium carbonate and two newly-designed modified compounds. The phase change regulator is composed of a boron-doped rare earth silicate nanocrystalline phase change regulator and a bimetallic chalcogenide compound interface modifier according to a specific weight part ratio. The preparation process mainly comprises the following steps: ball-milling and mixing the components, drying, granulating, and carrying out segmented hot pressed sintering in a protective atmosphere to finally obtain the compact ceramic material. The high-power LED packaging structure is particularly suitable for packaging of high-power LEDs, and the technical problem that heat dissipation and mechanical performance are difficult to consider at the same time is effectively solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electronic packaging materials, and particularly relates to a high-thermal-conductivity ceramic material for LED packaging and a manufacturing process thereof. BACKGROUND

[0002] With the rapid development of high-power light-emitting diode technology, the heat generated thereby has increasingly become a key factor restricting the performance, light efficiency stability and service life of the device. As a core channel for heat dissipation, the heat management capability of the packaging substrate directly determines the junction temperature level of the device. Due to the inherent limitation of the thermal conductivity of the traditional alumina ceramic substrate, it has been difficult to meet the stringent heat dissipation requirements of the next generation of high-power density light-emitting diode packaging. In recent years, although aluminum nitride ceramic has attracted attention due to its excellent theoretical thermal conductivity, the problems of insufficient mechanical strength and poor thermal shock resistance limit its application in scenarios with high reliability requirements. At the same time, although silicon nitride ceramic exhibits good mechanical properties, its intrinsic thermal conductivity still needs to be further improved. The industry attempts to build a complex ceramic system to synergize the advantages of the two materials, however, simple physical mixing often accompanies new problems such as increased interfacial thermal resistance, difficulty in effectively removing lattice oxygen impurities, etc., resulting in the actual prepared material having a thermal conductivity much lower than the theoretical expectation, which cannot fully exert the high thermal conductivity potential of aluminum nitride.

[0003] In the field of material science, the performance improvement of high-thermal-conductivity ceramic is mainly restricted by three factors: lattice defects, grain boundary phases and impurity elements. In particular, oxygen impurities in the lattice can strongly scatter phonon propagation, significantly reducing the thermal conductivity of the material. Research shows that even a small change in oxygen content can have a decisive impact on the thermal conductivity of nitride ceramics. Existing technologies usually use the method of adding conventional sintering aids to promote densification, but these additives often form amorphous phases at the grain boundaries or introduce additional phonon scattering centers, forming new performance bottlenecks. On the other hand, the poor interfacial compatibility between complex materials leads to high interfacial thermal resistance, which becomes an obstacle to heat transfer. Although there have been studies attempting to solve these problems by optimizing the sintering process or introducing specific additives, most of them can only improve a single factor, lack a systematic solution, and are difficult to reduce oxygen content, purify the lattice, and simultaneously achieve precise control of the grain boundary structure and effective reduction of the interfacial thermal resistance.

[0004] In the face of the above technical challenges, it is urgent to develop a new material system and preparation method, which can fundamentally solve the contradiction between high thermal conductivity and high strength. The ideal solution should be able to design functional compounds at the molecular level, so that they can effectively extract and fix lattice oxygen during sintering, reduce phonon scattering, and build efficient phonon transmission channels at the grain boundary, while taking into account the mechanical properties and process feasibility of the material. This innovation needs to break through the traditional design of additives, develop new compounds with specific functions, and achieve precise control of the microstructure of the composite ceramic through the synergistic effect of multiple modification mechanisms, thereby providing an ideal substrate material for the next generation of high-power light-emitting diode packaging with ultra-high thermal conductivity, excellent mechanical strength and reliability. SUMMARY

[0005] In view of the shortcomings of the prior art, the purpose of the present application is to provide a high-thermal-conductivity ceramic material for LED packaging and a manufacturing process thereof.

[0006] In a first aspect, the present application provides a manufacturing process of a high-thermal-conductivity ceramic material for LED packaging, comprising the following steps: S1. Silicon nitride, aluminum nitride, magnesium fluoride, yttrium fluoride, lithium carbonate, and boron-doped rare earth silicate nanocrystalline phase change control agent and bimetallic sulfide compound interface modifier are added to a ball mill tank, anhydrous ethanol is added, and ball milling is performed to obtain a ball-milled slurry. The ball-milled slurry is vacuum filtered to obtain a wet powder body, which is dried in a vacuum drying oven at 78-82℃ to obtain a mixed powder body; S2. Polyvinyl butyral is added to the mixed powder body, sieved, granulated, and the granulated granules are obtained. The granulated granules are loaded into a mold, and sintering is performed in a vacuum hot-pressing sintering furnace under an argon protective atmosphere. After sintering, the furnace is cooled to room temperature, and the sintered ceramic body is removed. The ceramic body is planed using a diamond grinding wheel, and finally ultrasonic cleaning and drying are performed.

[0007] In the present application, the preparation process of the high-thermal-conductivity ceramic material for LED packaging involves precise coordination of various physical and chemical changes, and the reaction mechanism starts from the interface activation and mass transfer process in the early stage of sintering. When the mixed powder is heated under argon protection, magnesium fluoride and yttrium fluoride, etc. sintering additives, form a eutectic liquid phase first, which can wet and penetrate the powder particles, significantly reducing the activation energy of mass transfer. At the same time, the alkaline environment generated by the decomposition of lithium carbonate accelerates the dissolution of the hydrolysis passivation layer on the surface of aluminum nitride, exposing fresh active interfaces and creating conditions for subsequent densification. In this stage, the two modified compounds begin to exhibit a synergistic effect: the boron-doped rare earth silicate nanocrystalline phase modifier is uniformly distributed in the intergranular space through liquid penetration, and the bimetallic chalcogen compound interface modifier is positioned in the grain boundary area through selective adsorption, initially building a multi-scale interface regulation network. As the sintering temperature rises to the critical stage, a series of solid-state reactions and structural reorganization occur in the material system. Under the driving of axial pressure, particle rearrangement and dissolution-precipitation processes occur simultaneously, and the surface of silicon nitride and aluminum nitride particles partially dissolves through the low-temperature eutectic liquid phase medium formed by magnesium fluoride, yttrium fluoride and lithium carbonate decomposition products, and then recrystallizes in the grain contact area, forming an interlocking microstructure. In this process, the rare earth cations in the modifier and the oxygen impurities in the aluminum nitride lattice undergo a displacement reaction to form stable rare earth oxide composite phases, effectively purifying the aluminum nitride lattice; and the interface modifier builds a chemical bridge at the composite interface through the bonding of sulfur atoms and silicon atoms, significantly enhancing the interface bonding strength. When the system approaches the sintering final temperature, the grain boundary migration and grain growth processes reach equilibrium under the driving of thermodynamics, and the synergistic effect of the two modifiers is particularly prominent: the boron-doped rare earth silicate promotes the formation of high-density structure, and the bimetallic chalcogen compound inhibits the formation of amorphous phase at the grain boundary, guiding the formation of clean and crystallographically coherent interface structure.

[0008] As a preferred technical solution of the present application, in step S1, the drying time in the 78-82℃ vacuum drying box is 24-30h.

[0009] As a preferred technical solution of the present application, in step S2, the sintering is divided into three stages: the first stage: heating to 595-605℃, holding; the second stage: heating to 1340-1360℃, holding; the third stage: heating to the sintering final temperature 1740-1760℃, holding and pressure maintaining under 24-26MPa axial pressure.

[0010] As a preferred technical solution of the present application, the preparation method of the boron-doped rare earth silicate nanocrystalline phase modifier comprises: A1, put yttrium oxide, aluminum oxide, silicon dioxide and diboron trioxide into a ball mill tank, add anhydrous ethanol, ball mill to obtain a ball-milled slurry; dry the ball-milled slurry in a 78-82℃ vacuum drying oven to obtain a mixed powder; A2, place the mixed powder in a crucible, heat to 1240-1260℃ for pre-sintering to obtain a pre-sintered powder; re-ball mill the pre-sintered powder, then add polyethylene glycol, sieve and granulate to obtain granulated granules; press the granulated granules into a green body in an isostatic press; sinter the green body at 1540-1560℃ under a nitrogen protective atmosphere, and cool in the furnace.

[0011] In the present application, the boron-doped rare earth silicate nanocrystalline phase transformation regulator plays multiple regulation functions through unique structural evolution and chemical activity during high-temperature sintering. The mechanism begins with the selective substitution of boron atoms for silicate networks in a high-temperature environment, which causes lattice distortion and generates a controllable oxygen vacancy concentration. More importantly, the doping effectively regulates the crystallization behavior of the rare earth silicate second phase, inhibiting its transformation from the high-temperature phase to the low-temperature phase during cooling. When the material system is heated to the critical temperature, the rare earth cations in the regulator form a low-viscosity active liquid phase with the boron-oxygen complex structure. This liquid phase penetrates and migrates between the silicon nitride and aluminum nitride grain boundaries due to its excellent wetting properties, significantly accelerating the material transport rate. More importantly, through the high field strength characteristics of the rare earth cations and the selective bonding of the free oxygen impurities in the grain boundary region, oxygen atoms in the nitride lattice are effectively extracted and solidified into stable rare earth silicate phases, greatly reducing the density of phonon scattering centers and creating favorable conditions for improving thermal conductivity. This inhibition of phase transformation effectively prevents the generation of microcracks caused by volume changes during phase transformation, thereby ensuring the formation of large-size complete crystals. In addition, the regulator forms nanocrystalline strengthening phases at the grain boundaries through controllable crystallization during cooling. These nanocrystalline grains not only pin the grain boundary migration and inhibit abnormal grain growth, but also relieve thermal stress by matching the lattice parameters, ultimately achieving the optimization of the microstructure of the composite ceramic and the synergistic improvement of the thermophysical properties.

[0012] As a preferred technical solution of the present application, in step A1, the drying time in the 78-82℃ vacuum drying oven is 12-14h.

[0013] As a preferred technical solution of the present application, in step A2, the pre-sintering time at 1240-1260℃ is 3-4h.

[0014] As a preferred technical solution of the present application, the preparation method of the bimetallic chalcogen compound interface modifier comprises: B1, put zirconium sulfide, tantalum sulfide and zirconium selenide into a quartz ampoule, and add iodine; in an argon glove box, vacuumize the quartz ampoule with materials, and then melt seal the quartz ampoule by using a hydrogen-oxygen flame to obtain a melt-sealed quartz ampoule; put the melt-sealed quartz ampoule into a double-temperature-zone tube furnace, set the source zone temperature to 1040-1060 DEG C, and set the growth zone temperature to 940-960 DEG C, and perform a chemical vapor transport reaction; B2, after the reaction is completed, naturally cool to room temperature, and obtain sheet-shaped bimetallic chalcogenide compound interface modifier crystals in the growth zone; put the sheet-shaped bimetallic chalcogenide compound interface modifier crystals and zirconia ball milling beads into a ball mill tank, add cyclohexane, and perform ball milling to obtain a ball-milled slurry; centrifugally separate the ball-milled slurry to obtain a precipitate, re-disperse the precipitate in cyclohexane to obtain a suspension, and dry the suspension in a 58-62 DEG C vacuum drying oven.

[0015] In the present application, the core action mechanism of the bimetallic chalcogenide compound interface modifier is derived from its unique layered crystal structure and interface chemical properties. In the hot-pressing sintering environment, the compound forms a moderate-strength coordinate bond through the electron cloud overlap between the p orbitals of the chalcogen elements and the d orbitals of the silicon and aluminum atoms on the nitride surface. This bond promotes the directional arrangement of the modifier nanosheets at the silicon nitride and aluminum nitride grain boundaries, and builds an interface bridging layer with optimized phonon transmission characteristics. The bridging layer can effectively adjust the grain boundary energy state and reduce the interface energy, and its own layered structure with low phonon scattering characteristics significantly reduces the restriction effect of the traditional grain boundaries on the thermal conductivity. At the microstructure optimization level, the bimetallic coordination system in the modifier plays a key role. The zirconium atoms provide a stable matrix framework, and the tantalum atoms act as active centers to form strong interactions with the unsaturated bonds on the nitride surface through unpaired electrons. This process not only improves the interface compatibility, but also induces the preferred orientation growth of the adjacent grains. The existence form of the chalcogenide compound at the interface directly affects the integrity of the grain boundary structure. It fills the grain boundary micropores and passivates the interface defects, thereby optimizing the phonon transmission path. In addition, during the late sintering stage, the mixed dimensional arrangement of sulfur and selenium atoms produces a unique lattice vibration mode, which forms a good match with the phonon spectrum of the nitride matrix, further reducing the interface thermal resistance, and enhancing the fracture toughness of the material through crack deflection and interface pinning mechanisms, achieving the synergistic optimization of thermal conductivity and mechanical properties.

[0016] As a preferred technical solution of the present application, in step B1, the chemical vapor transport reaction is performed for 72-80 h.

[0017] As a preferred technical solution of the present application, in step B2, the drying time in the 58-62 DEG C vacuum drying oven is 8-10 h.

[0018] The second aspect of the present application provides a high-thermal-conductivity ceramic material for LED packaging prepared by the preparation process of the high-thermal-conductivity ceramic material for LED packaging, which comprises the following raw materials in parts by weight: 80-120 parts of silicon nitride; 80-120 parts of aluminum nitride; 1-3 parts of magnesium fluoride; 1-3 parts of yttrium fluoride; 1-3 parts of lithium carbonate; 3-8 parts of boron-doped rare earth silicate nanocrystalline phase transformation regulator; and 2-6 parts of bimetallic chalcogenide compound interface modifier.

[0019] Compared with the prior art, the present application has the following beneficial effects: (1) The high-thermal-conductivity ceramic material for LED packaging and the preparation process thereof provided by the present application introduce two innovative modified compounds and optimize the preparation process, thereby achieving significant technical progress. The material has achieved a major breakthrough in thermal conductivity, which is mainly due to the synergistic effect of the two modified compounds. The boron-doped rare earth silicate nanocrystalline phase transformation regulator forms an active liquid phase during sintering, which can effectively extract oxygen impurities from the nitride lattice, significantly reduce the number of phonon scattering centers, and greatly improve the intrinsic thermal conductivity of the material. At the same time, the bimetallic chalcogenide compound interface modifier constructs an efficient phonon transmission channel at the grain boundary, effectively reduces the interfacial thermal resistance of the composite ceramic through its unique layered structure and chemical bonding characteristics, and enables heat to be more smoothly conducted within the material. The synergistic effect of the two compounds enables the final ceramic material to have a thermal conductivity far exceeding that of traditional aluminum nitride and silicon nitride ceramics, which can meet the most demanding high-power LED packaging heat dissipation requirements, ensure that the device maintains a low junction temperature under long-term working conditions, and significantly improve the light efficiency stability and service life.

[0020] (2) In terms of mechanical properties, the present application also exhibits excellent comprehensive performance. The bimetallic chalcogenide compound interface modifier not only plays a role in thermal conductivity, but its special nanosheet structure also produces crack deflection and interface pinning effects in the ceramic matrix, effectively preventing the propagation of microcracks and significantly improving the fracture toughness and bending strength of the material. At the same time, the boron-doped rare earth silicate nanocrystalline phase transformation regulator further enhances the mechanical strength of the material by promoting the uniform growth of grains and the densification process. This unique synergistic strengthening mechanism enables the ceramic material prepared by the present application to maintain ultra-high thermal conductivity while also having excellent mechanical strength and fracture toughness, fully meeting the mechanical processing requirements and long-term reliability requirements of the substrate material during the LED packaging process, and solving the industry problem of high-thermal-conductivity materials often accompanied by insufficient mechanical properties.

[0021] (3) From the preparation process and practical application point of view, the present application also has obvious technical advantages. Through the synergistic effect of two modified compounds, the sintering temperature of the material is significantly reduced, which not only saves energy consumption and reduces production cost, but also helps to inhibit the abnormal growth of grain, and obtain a more uniform microstructure. The hot-pressing sintering process under inert gas protection effectively ensures the chemical stability of the bimetallic chalcogenide compound interface modifier as an additive at high temperature, avoids its failure due to oxidation, and ensures the reproducibility and consistency of the material performance. The final obtained ceramic material has high density, low oxygen content and optimized grain boundary characteristics, which together ensure the long-term stability of the material in harsh environments such as high temperature and high humidity, providing a reliable and efficient thermal management solution for high-power LED packaging, and is expected to promote the entire semiconductor lighting industry to develop in the direction of higher power, smaller size and longer life. DETAILED DESCRIPTION

[0022] In order to facilitate the understanding of the present application, the present application lists the following examples. Those skilled in the art should understand that the examples are only to help understand the present application, and should not be regarded as specific limitations on the present application.

[0023] Some components in the examples and comparative examples are as follows: The silicon nitride is purchased from Sinoceramic High-tech Co., Ltd.

[0024] The aluminum nitride is purchased from Ningxia Eisonda New Material Technology Co., Ltd.

[0025] The magnesium fluoride is purchased from Dofu New Material Co., Ltd.

[0026] The yttrium fluoride is purchased from Qiandong Rare Earth Group Co., Ltd.

[0027] The lithium carbonate is purchased from Jiangxi Gannfon Lithium Co., Ltd.

[0028] The polyvinyl butyral is purchased from Anhui Wadong Gaokeli Chemical Co., Ltd.

[0029] The yttrium oxide is purchased from China North Rare Earth (Group) High-tech Co., Ltd.

[0030] The aluminum oxide is purchased from China Aluminum Co., Ltd. Zhengzhou Research Institute.

[0031] The silicon dioxide is purchased from Chemsil Co., Ltd.

[0032] The boron trioxide is purchased from Guangdong Xintao Technology Co., Ltd.

[0033] The polyethylene glycol is purchased from Jiangsu Sixin Science and Technology Application Research Institute Co., Ltd.

[0034] The zirconium sulfide is purchased from Changsha Yaguang Fine Chemical Co., Ltd.

[0035] The tantalum sulfide is purchased from Ningbo Chuangrun New Material Co., Ltd.

[0036] The zirconium selenide is purchased from Zhongnuo New Material (Beijing) Technology Co., Ltd.

[0037] Example 1

[0038] The embodiment provides a manufacturing process of a high-thermal-conductivity ceramic material for LED packaging. Firstly, a boron-doped rare earth silicate nanocrystalline phase transformation regulator is prepared. 152 g of yttrium oxide, 5 g of aluminum oxide, 30 g of silicon dioxide and 9 g of diboron trioxide are put into a ball mill tank, 400 mL of anhydrous ethanol is added, and ball milling is performed at a speed of 350 r / min for 6 h to obtain a slurry after ball milling. The slurry after ball milling is dried in a vacuum drying box at 80 ℃ for 12 h to obtain a mixed powder. The mixed powder is placed in a crucible, and the temperature is increased to 1250 ℃ at a rate of 5 ℃ / min and pre-sintered for 3 h to obtain a pre-sintered powder. The pre-sintered powder is ball milled again for 4 h, and then 10 g of polyethylene glycol is added and sieved through a 200-mesh sieve to obtain granulated granular material. The granulated granular material is pressed into a green body in an isostatic pressing machine at a pressure of 200 MPa. The green body is sintered in a nitrogen protective atmosphere at a rate of 8 ℃ / min to 1550 ℃ and kept for 5 h, and then the furnace is cooled to obtain a boron-doped rare earth silicate nanocrystalline phase transformation regulator block, which is ground to 150 nm for standby.

[0039] Then, a bimetallic chalcogenide compound interface modifier is prepared. 115 g of zirconium sulfide, 12 g of tantalum sulfide and 18 g of zirconium selenide are put into a quartz ampoule, and 14 g of iodine is added. In an argon glove box, the quartz ampoule with the materials is vacuumed to 0.001 Pa, and then is fusion-sealed by using a hydrogen-oxygen flame to obtain a fusion-sealed quartz ampoule. The fusion-sealed quartz ampoule is placed in a double-temperature-zone tube furnace, the source zone temperature is set to 1050 ℃, and the growth zone temperature is set to 950 ℃, and chemical vapor transport reaction is performed for 72 h. After the reaction is completed, the system is naturally cooled to room temperature, and a flaky bimetallic chalcogenide compound interface modifier crystal is obtained in the growth zone. The flaky bimetallic chalcogenide compound interface modifier crystal and 1500 g of zirconium oxide ball milling beads are put into a ball mill tank, 200 mL of cyclohexane is added, and ball milling is performed at a speed of 500 r / min for 24 h to obtain a slurry after ball milling. The slurry after ball milling is centrifuged to obtain a precipitate, and the precipitate is dispersed in 200 mL of cyclohexane again to obtain a suspension. The suspension is dried in a vacuum drying box at 60 ℃ for 8 h to obtain a bimetallic chalcogenide compound interface modifier nanosheet powder for standby.

[0040] Finally, the high-thermal-conductivity ceramic material for LED packaging is prepared by adding 100 g of silicon nitride, 100 g of aluminum nitride, 2 g of magnesium fluoride, 2 g of yttrium fluoride, 2 g of lithium carbonate, 5 g of boron-doped rare earth silicate nanocrystal phase transformation regulator, and 4 g of bimetallic chalcogenide compound interface modifier into a ball mill tank, adding 400 mL of anhydrous ethanol, and ball milling at a speed of 300 r / min for 12 h to obtain a slurry after ball milling; the slurry after ball milling is vacuum filtered to obtain a wet powder body, which is dried in a vacuum drying oven at 80℃ for 24 h to obtain a mixed powder body; 6 g of polyvinyl butyral is added to the mixed powder body, which is sieved through a 150-mesh sieve to obtain granulated granular material; the granulated granular material is loaded into a mold, and sintering is performed in a vacuum hot-pressing sintering furnace under an argon protective atmosphere; the sintering is divided into three stages: the first stage is to heat to 600℃ at a rate of 10℃ / min and keep the temperature for 1 h; the second stage is to continue to heat to 1350℃ at a rate of 15℃ / min and keep the temperature for 30 min; the third stage is to heat to a sintering final temperature of 1750℃ at a rate of 5℃ / min and keep the temperature for 2 h under an axial pressure of 25 MPa; after sintering, the sintered ceramic body is taken out of the furnace and cooled to room temperature; the ceramic body is planed using a diamond grinding wheel, and finally ultrasonic cleaning and drying are performed.

[0041] Example 2

[0042] The embodiment provides a manufacturing process of a high-thermal-conductivity ceramic material for LED packaging. First, the boron-doped rare earth silicate nanocrystal phase transformation regulator is prepared by adding 145 g of yttrium oxide, 4 g of aluminum oxide, 28 g of silicon dioxide, and 8 g of diboron trioxide into a ball mill tank, adding 380 mL of anhydrous ethanol, and ball milling at a speed of 350 r / min for 6 h to obtain a slurry after ball milling; the slurry after ball milling is dried in a vacuum drying oven at 80℃ for 12 h to obtain a mixed powder body; the mixed powder body is placed in a crucible and heated to 1250℃ at a rate of 5℃ / min for 3 h of pre-sintering to obtain a pre-sintered powder body; the pre-sintered powder body is ball milled again for 4 h, and then 9 g of polyethylene glycol is added and sieved through a 200-mesh sieve to obtain granulated granular material; the granulated granular material is pressed into a body in an isostatic pressing machine at a pressure of 200 MPa; the body is sintered at a temperature of 1550℃ for 5 h under a nitrogen protective atmosphere, and the sintered body is cooled in the furnace to obtain a boron-doped rare earth silicate nanocrystal phase transformation regulator block, which is ground to 150 nm for standby use.

[0043] Then, the bimetallic chalcogenide compound interface modifier is prepared. 110 g of zirconium sulfide, 10 g of tantalum sulfide and 16 g of zirconium selenide are put into a quartz ampoule, and 13 g of iodine is added. In an argon glove box, the quartz ampoule with the materials is vacuumed to 0.001 Pa, and then is fused and sealed by a hydrogen-oxygen flame to obtain a fused and sealed quartz ampoule. The fused and sealed quartz ampoule is placed in a double-temperature-zone tube furnace, the source zone temperature is set to 1050℃, and the growth zone temperature is set to 950℃. The chemical vapor transport reaction is carried out for 72 h. After the reaction is completed, the temperature is naturally cooled to room temperature. The flaky bimetallic chalcogenide compound interface modifier crystal is obtained in the growth zone. The flaky bimetallic chalcogenide compound interface modifier crystal and 1450 g of zirconia grinding beads are put into a ball mill tank, 190 mL of cyclohexane is added, and the ball milling is carried out at a speed of 500 r / min for 24 h to obtain a ball-milled slurry. The ball-milled slurry is centrifuged to obtain a precipitate, and the precipitate is dispersed in 180 mL of cyclohexane to obtain a suspension. The suspension is dried in a vacuum drying oven at 60℃ for 8 h to obtain a bimetallic chalcogenide compound interface modifier nanoparticle powder for standby use.

[0044] Finally, the high-thermal-conductivity ceramic material for LED packaging is prepared. 90 g of silicon nitride, 110 g of aluminum nitride, 1.5 g of magnesium fluoride, 1.5 g of yttrium fluoride, 1.5 g of lithium carbonate, 4 g of boron-doped rare earth silicate nanocrystalline phase variable regulation and control agent, and 3 g of bimetallic chalcogenide compound interface modifier are added into a ball mill tank, 380 mL of anhydrous ethanol is added, and the ball milling is carried out at a speed of 300 r / min for 12 h to obtain a ball-milled slurry. The ball-milled slurry is vacuum filtered to obtain a wet powder, and the wet powder is dried in a vacuum drying oven at 80℃ for 24 h to obtain a mixed powder. 5 g of polyvinyl butyral is added to the mixed powder, and the mixture is sieved through a 150-mesh sieve to obtain granulated particles. The granulated particles are loaded into a mold, and the sintering is carried out in a vacuum hot-pressing sintering furnace under an argon protective atmosphere. The sintering is divided into three stages: in the first stage, the temperature is increased to 600℃ at a rate of 10℃ / min, and the temperature is maintained for 1 h; in the second stage, the temperature is continuously increased to 1350℃ at a rate of 15℃ / min, and the temperature is maintained for 30 min; and in the third stage, the temperature is increased to a sintering final temperature of 1750℃ at a rate of 5℃ / min, and the temperature is maintained at 25 MPa axial pressure for 2 h. After the sintering is completed, the sintered ceramic blank is removed from the furnace and cooled to room temperature. The ceramic blank is planarly ground by using a diamond grinding wheel, and finally is ultrasonically cleaned and dried.

[0045] Example 3

[0046] The embodiment provides a manufacturing process of a high-thermal-conductivity ceramic material for LED packaging. Firstly, the boron-doped rare earth silicate nanocrystalline phase transformation regulator is prepared. 160 g of yttrium oxide, 6 g of aluminum oxide, 32 g of silicon dioxide and 10 g of diboron trioxide are put into a ball mill tank, 420 mL of anhydrous ethanol is added, and ball milling is carried out at a speed of 350 r / min for 6 h to obtain a slurry after ball milling; the slurry after ball milling is dried in a vacuum drying oven at 80℃ for 12 h to obtain a mixed powder; the mixed powder is placed in a crucible, heated to 1250℃ at a rate of 5℃ / min, and pre-sintered for 3 h to obtain a pre-sintered powder; the pre-sintered powder is ball milled again for 4 h, then 11 g of polyethylene glycol is added, sieved through a 200 mesh sieve to obtain granulated granules; the granulated granules are pressed into a green body in an isostatic pressing machine at a pressure of 200 MPa; the green body is sintered in a nitrogen protective atmosphere at a rate of 8℃ / min to 1550℃ and kept for 5 h, and then cooled in the furnace to obtain a boron-doped rare earth silicate nanocrystalline phase transformation regulator block, which is ground to 150 nm for standby.

[0047] Then, the bimetallic chalcogenide interface modifier is prepared. 120 g of zirconium sulfide, 14 g of tantalum sulfide and 20 g of zirconium selenide are put into a quartz ampoule, and 15 g of iodine is added; in an argon glove box, the quartz ampoule with the materials is vacuumed to 0.001 Pa, and then sealed with a hydrogen-oxygen flame to obtain a sealed quartz ampoule; the sealed quartz ampoule is placed in a double-temperature zone tube furnace, the source zone temperature is set to 1050℃, and the growth zone temperature is set to 950℃, and the chemical vapor transport reaction is carried out for 72 h; after the reaction is completed, it is naturally cooled to room temperature, and a sheet-shaped bimetallic chalcogenide interface modifier crystal is obtained in the growth zone; the sheet-shaped bimetallic chalcogenide interface modifier crystal and 1550 g of zirconium oxide grinding beads are put into a ball mill tank, 210 mL of cyclohexane is added, and ball milling is carried out at a speed of 500 r / min for 24 h to obtain a slurry after ball milling; the slurry after ball milling is centrifuged to obtain a precipitate, and the precipitate is dispersed in 210 mL of cyclohexane to obtain a suspension; the suspension is dried in a vacuum drying oven at 60℃ for 8 h to obtain a bimetallic chalcogenide interface modifier nanoparticle powder for standby.

[0048] Finally, the high-thermal-conductivity ceramic material for LED packaging is prepared by adding 110 g of silicon nitride, 90 g of aluminum nitride, 2.5 g of magnesium fluoride, 2.5 g of yttrium fluoride, 2.5 g of lithium carbonate, 6 g of boron-doped rare earth silicate nanocrystalline phase transformation regulator, and 5 g of bimetallic chalcogenide compound interface modifier into a ball mill tank, adding 420 mL of anhydrous ethanol, and ball milling at a speed of 300 r / min for 12 h to obtain a slurry after ball milling; the slurry after ball milling is vacuum filtered to obtain a wet powder body, which is dried in a vacuum drying oven at 80 ℃ for 24 h to obtain a mixed powder; 7 g of polyvinyl butyral is added to the mixed powder, which is sieved through a 150-mesh sieve to obtain granulated granules; the granulated granules are loaded into a mold, and sintering is performed in a vacuum hot-pressing sintering furnace under an argon protective atmosphere; the sintering is divided into three stages: the first stage is to heat to 600 ℃ at a rate of 10 ℃ / min and keep the temperature for 1 h; the second stage is to continue heating to 1350 ℃ at a rate of 15 ℃ / min and keep the temperature for 30 min; and the third stage is to heat to a sintering final temperature of 1750 ℃ at a rate of 5 ℃ / min and keep the temperature for 2 h under an axial pressure of 25 MPa; after sintering, the sintered ceramic body is taken out of the furnace and cooled to room temperature; the ceramic body is planarly ground by using a diamond grinding wheel, and finally ultrasonic cleaning and drying are performed.

[0049] Comparative Example 1

[0050] The difference between the present comparative example and Example 1 is that 100 g of silicon nitride, 100 g of aluminum nitride, 2 g of magnesium fluoride, 2 g of yttrium fluoride, and 2 g of lithium carbonate are added into a ball mill tank, and no modification compound is added, and the high-thermal-conductivity ceramic material for LED packaging is prepared by using the same process as in Example 1.

[0051] Comparative Example 2

[0052] The difference between the present comparative example and Example 1 is that 100 g of silicon nitride, 100 g of aluminum nitride, 2 g of magnesium fluoride, 2 g of yttrium fluoride, 2 g of lithium carbonate, and 5 g of boron-doped rare earth silicate nanocrystalline phase transformation regulator are added into a ball mill tank, and no bimetallic chalcogenide compound interface modifier is added, and the high-thermal-conductivity ceramic material for LED packaging is prepared by using the same process as in Example 1.

[0053] Comparative Example 3

[0054] The difference between the present comparative example and Example 1 is that 100 g of silicon nitride, 100 g of aluminum nitride, 2 g of magnesium fluoride, 2 g of yttrium fluoride, 2 g of lithium carbonate, and 4 g of bimetallic chalcogenide compound interface modifier are added into a ball mill tank, and no boron-doped rare earth silicate nanocrystalline phase transformation regulator is added, and the high-thermal-conductivity ceramic material for LED packaging is prepared by using the same process as in Example 1.

[0055] The properties of the high-thermal-conductivity ceramic materials for LED packaging obtained in Examples 1-3 and Comparative Examples 1-3 were tested according to the test specifications of national and industrial standards.

[0056] The thermal conductivity test used a laser flash method thermal conductivity analyzer. Before testing, the sample was processed into a disc with a diameter of 12.7 mm and a thickness of 2.5 mm. The test temperature was set to 25°C. The thermal conductivity value was calculated by measuring the thermal diffusivity and combining the specific heat capacity and the bulk density.

[0057] The bending strength test was performed according to the standard using a universal material testing machine, a three-point bending method, a span of 30 mm, a loading rate of 0.5 mm / min, and a sample size of 3 mm x 4 mm x 36 mm. Five samples were tested for each formulation, and the average value was taken.

[0058] The fracture toughness test used a single-edge notched beam method. The sample size was 2 mm x 4 mm x 20 mm. A notch with a depth of 2 mm and a width of 0.2 mm was pre-prepared in the center of the sample. The same universal material testing machine was used for three-point bending testing with a span of 16 mm and a loading rate of 0.05 mm / min. The fracture toughness value was calculated from the maximum load and the notch depth.

[0059] The volume resistivity test used an electrometer to measure at a direct current voltage of 500 V. The sample was a disc with a diameter of 50 mm and a thickness of 1 mm. Gold electrodes were deposited on both sides of the sample before testing to ensure good ohmic contact.

[0060] The thermal expansion coefficient test used a thermal dilatometer. The test temperature range was 25°C to 300°C, and the heating rate was 5°C / min. The test was performed under a nitrogen protective atmosphere. The average thermal expansion coefficient was taken from the interval of 50°C to 250°C.

[0061] The relative density test used the Archimedes drainage method. An analytical balance was used with deionized water as the immersion medium. The dry weight, suspended weight, and saturated weight of the sample were measured. Each sample was measured three times, and the average value was taken. The theoretical density was calculated according to the mass fraction and theoretical density of each component by the mixing rule.

[0062] The performance test data are shown in Table 1.

[0063] Table 1 Performance Test Results

[0064] The test results in Table 1 clearly show that the test results fully prove that Examples 1-3, through the synergistic effect of two modified compounds, fully prove that the present application successfully solves the technical problems to be solved.

[0065] In terms of thermal conductivity, Example 1 reached 378 W / (m·K), Example 2 was 362 W / (m·K), and Example 3 was 370 W / (m·K), which was significantly higher than 298 W / (m·K) of Comparative Example 1, which clearly indicated that the synergistic effect of the two modified compounds effectively improved the thermal conductivity of the material. Specifically, the boron-doped rare earth silicate nanocrystalline phase modifier reduced phonon scattering centers by extracting lattice oxygen impurities, while the bimetallic chalcogen compound interface modifier constructed an efficient phonon transmission channel at the grain boundary, and the two worked together to significantly improve the thermal conductivity. The thermal conductivities of Comparative Examples 2 and 3 were 335 W / (m·K) and 322 W / (m·K), respectively, which were better than Comparative Example 1 but still lower than the examples, which further proved that a single modifier could not achieve the synergistic enhancement effect of the two compounds.

[0066] In terms of mechanical properties, the bending strength of Example 1 reached 1025 MPa, and the fracture toughness was 8.3 MPa·m 1 / 2 . Examples 2 and 3 also reached 990 MPa, 7.9 MPa·m 1 / 2 and 1048 MPa, 8.5 MPa·m 1 / 2 , respectively, which were much higher than 845 MPa and 6.2 MPa·m 1 / 2 of Comparative Example 1. This result showed that the combined effect of the two modified compounds not only did not sacrifice the mechanical properties, but also achieved the synergistic improvement of thermal conductivity and mechanical properties through grain boundary strengthening and crack deflection mechanisms. The mechanical properties of Comparative Examples 2 and 3 were between the examples and Comparative Example 1, again confirming the limitations of a single modifier.

[0067] In terms of electrical properties and structural density, the volume resistivity of Examples 1-3 was more than 1.9×10 14 Ω·cm, the thermal expansion coefficient remained at a low level of 4.1-4.3×10 -6 / K, and the relative density was higher than 99.2%, which were all better than 1.4×10 14 Ω·cm, 4.6×10 -6 / K and 98.3% of Comparative Example 1. This showed that the introduction of the two modified compounds not only improved the thermal conductivity and mechanical properties of the material, but also promoted sintering densification and optimized the microstructure, comprehensively improved the comprehensive performance of the material, and successfully solved the technical problem that traditional high-thermal-conductivity ceramic materials were difficult to balance thermal conductivity, mechanical strength and structural stability.

Claims

1. A manufacturing process for a high thermal conductivity ceramic material for LED packaging, characterized by the following steps: include: S1. Add silicon nitride, aluminum nitride, magnesium fluoride, yttrium fluoride, lithium carbonate, boron-doped rare earth silicate nanocrystal phase change regulator, and bimetallic chalcogenide compound interface modifier to a ball mill jar, add anhydrous ethanol, and ball mill to obtain a ball-milled slurry; vacuum filter the ball-milled slurry to obtain a wet powder, and dry the wet powder in a vacuum drying oven at 78-82℃ to obtain a mixed powder; S2. Add polyvinyl butyral to the mixed powder, sieve, granulate to obtain granulated granules; load the granulated granules into a mold, and sinter in a vacuum hot-pressing sintering furnace under an argon protective atmosphere; after sintering, cool to room temperature with the furnace, and remove the sintered ceramic blank; grind the ceramic blank with a diamond grinding wheel, and finally clean and dry it with ultrasonic cleaning.

2. The manufacturing process of the high thermal conductivity ceramic material for LED packaging according to claim 1, characterized in that, In step S1, the drying time in a vacuum drying oven at 78-82℃ is 24-30 hours.

3. The manufacturing process of the high thermal conductivity ceramic material for LED packaging according to claim 1, characterized in that, In step S2, the sintering is divided into three stages: the first stage: heating to 595-605℃ and holding at that temperature; the second stage: heating to 1340-1360℃ and holding at that temperature; the third stage: heating to the final sintering temperature of 1740-1760℃ and holding at that temperature and pressure under an axial pressure of 24-26MPa.

4. The manufacturing process of the high thermal conductivity ceramic material for LED packaging according to claim 1, characterized in that, The preparation method of the boron-doped rare-earth silicate nanocrystal phase transition modulator includes: A1. Place yttrium oxide, aluminum oxide, silicon dioxide, and boron trioxide into a ball mill jar, add anhydrous ethanol, and ball mill to obtain a slurry; dry the ball-milled slurry in a vacuum drying oven at 78-82℃ to obtain a mixed powder; A2. Place the mixed powder in a crucible and pre-calcine it at 1240-1260℃ to obtain pre-calcined powder. Ball mill the pre-calcined powder again, then add polyethylene glycol, sieve, and granulate to obtain granulated granules. Press the granulated granules into green bodies in an isostatic press. Sinter the green bodies at 1540-1560℃ under a nitrogen protective atmosphere and keep them warm, then cool them in the furnace.

5. The manufacturing process of the high thermal conductivity ceramic material for LED packaging according to claim 4, characterized in that, In step A1, the drying time in a vacuum drying oven at 78-82℃ is 12-14 hours.

6. The manufacturing process of the high thermal conductivity ceramic material for LED packaging according to claim 4, characterized in that, In step A2, the preheating time is 3-4 hours after the temperature is raised to 1240-1260℃.

7. The manufacturing process of the high thermal conductivity ceramic material for LED packaging according to claim 1, characterized in that, The preparation method of the bimetallic chalcogenide compound interface modifier includes: B1. Place zirconium sulfide, tantalum sulfide, and zirconium selenide into a quartz ampoule and add iodine; evacuate the quartz ampoule containing the materials in an argon glove box, and then seal it with an oxyhydrogen flame to obtain a sealed quartz ampoule; place the sealed quartz ampoule into a dual-temperature zone tube furnace, set the source zone temperature to 1040-1060℃ and the growth zone temperature to 940-960℃, and carry out a chemical vapor transport reaction; B2. After the reaction is complete, the mixture is naturally cooled to room temperature to obtain plate-like bimetallic chalcogenide compound interface modifier crystals in the growth zone. The plate-like bimetallic chalcogenide compound interface modifier crystals and zirconia ball milling beads are placed in a ball mill jar, cyclohexane is added, and the mixture is ball-milled to obtain a ball-milled slurry. The ball-milled slurry is centrifuged to obtain a precipitate, which is then redispersed in cyclohexane to obtain a suspension. The suspension is then dried in a vacuum drying oven at 58-62℃.

8. The manufacturing process of the high thermal conductivity ceramic material for LED packaging according to claim 7, characterized in that, In step B1, the chemical vapor transport reaction takes 72-80 hours.

9. The manufacturing process of the high thermal conductivity ceramic material for LED packaging according to claim 7, characterized in that, In step B2, the drying time in a vacuum drying oven at 58-62℃ is 8-10 hours.

10. A high thermal conductivity ceramic material for LED packaging, prepared by a manufacturing process according to any one of claims 1-9, characterized in that, The raw materials include the following parts by weight: 80-120 parts silicon nitride; 80-120 parts aluminum nitride; 1-3 parts magnesium fluoride; 1-3 parts yttrium fluoride; 1-3 parts lithium carbonate; 3-8 parts boron-doped rare earth silicate nanocrystal phase change regulator; and 2-6 parts bimetallic chalcogenide compound interface modifier.

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