Fine-grain beryllium oxide ceramic film substrate and preparation method thereof

Abstract

The invention relates to a fine-grain beryllium oxide ceramic film substrate and a preparation method thereof, belongs to the technical field of ceramics, and is used for solving at least one of the problems of large average grain size, high surface roughness, low heat conductivity, low breaking strength at room temperature and the like of a beryllium oxide ceramic substrate prepared by the existing method. The fine-grain beryllium oxide ceramic film substrate is prepared from the following raw materials in parts by weight: 99 to 99.5 parts of nano beryllium oxide, 0.2 to 0.5 part of magnesium aluminum silicate and 0.2 to 0.3 part of nano silicon dioxide. Through the synergistic effect of the nano beryllium oxide, the magnesium aluminum silicate and the nano silicon dioxide and the specific proportion, the volume density, the heat conductivity and the breaking strength of the beryllium oxide ceramic substrate are improved, and the grain size is reduced.

Description

Technical Field

[0001] The present invention relates to the field of ceramic technology, and particularly relates to a fine-grained beryllium oxide ceramic thin film substrate and a preparation method thereof. Background Art

[0002] Beryllium oxide ceramics are important parts for supporting electronic devices. Due to the characteristics of high thermal conductivity, good insulation, thermal shock resistance, low loss and good chemical stability of beryllium oxide ceramics, they are widely used for heat dissipation of high-power devices such as aviation. They have been widely used in electronic vacuum devices, high-power module thick film circuits, packaging devices, and optoelectronic devices. Microwave thin film electronic materials are developing towards the direction of being new, light, thin, with increasing frequency and power. Polished beryllium oxide ceramic substrates with low loss and stable dielectric constant are playing an increasingly important role in the fields of microwave electronics and aerospace.

[0003] At present, most beryllium oxide polished wafers are prepared by calcining beryllium oxide powder, then ball milling, spray granulation, dry pressing preforming and isostatic pressing, and then grinding and polishing after sintering. Due to the calcination of the powder in these beryllium oxide ceramic wafers, the crystal grains grow, the activity decreases, the sintering temperature of the ceramic is also relatively high, the holding time is long, the crystal grains of the ceramic are relatively large, which is not conducive to subsequent polishing processing, the yield is low, the surface roughness can generally only reach 0.08 - 0.1 μm, and the thermal conductivity is poor, the flexural strength is low, and the crystal grain size is large. Summary of the Invention

[0004] In view of the above analysis, the present invention aims to provide a fine-grained beryllium oxide ceramic thin film substrate and a preparation method thereof to solve at least one of the problems such as large average crystal grain size, high surface roughness, low thermal conductivity, and low room temperature flexural strength of the beryllium oxide ceramic substrate prepared by the existing method.

[0005] In a first aspect, the present invention provides a fine-grained beryllium oxide ceramic thin film substrate. By weight, the raw materials of the substrate include: 99 - 99.5 parts of nano beryllium oxide, 0.2 - 0.5 parts of magnesium aluminum silicate, and 0.2 - 0.3 parts of nano silicon dioxide.

[0006] Further, the raw materials further include 0.1 - 0.2 parts of nano yttrium oxide.

[0007] Further, the particle size of the nano beryllium oxide is 20 - 100 nm, the particle size of the magnesium aluminum silicate is 0.5 - 1 μm, the particle size of the nano silicon dioxide is 10 - 30 nm, and the particle size of the nano yttrium oxide is 30 - 40 nm.

[0008] In a second aspect, the present invention provides a preparation method of the fine-grained beryllium oxide ceramic thin film substrate, including the following steps: (1) Weigh and set aside according to the weight parts of each raw material; (2) Dissolve polyvinyl alcohol in water to obtain Solution A; (3) Add the reserved raw materials to water, stir and grind to obtain beryllium oxide slurry; (4) Add the said Solution A to the said beryllium oxide slurry, stir, spray granulate and dry to obtain granulated powder; (5) Subject the said granulated powder to hot press sintering, cut it into substrates, and subject the said substrates to thinning grinding and polishing treatments on both sides in sequence to obtain the fine-grained beryllium oxide ceramic film substrate.

[0009] Further, in step (2), the mass ratio of polyvinyl alcohol to water is 10-20:100.

[0010] Further, in step (3), the mass ratio of the total mass of the reserved raw materials to water is 20-54:46-50.

[0011] Further, in step (4), the mass ratio of the said beryllium oxide slurry to Solution A is 100:3-5.

[0012] Further, in step (4), the stirring time is ≥2 h, and the average particle size of the said granulated powder is 50-80 μm.

[0013] Further, for the said hot press sintering, the sintering temperature is 1600-1650 °C, the pressure is 20-30 MPa, and the heat preservation time is 10-30 min.

[0014] Further, in step (5), the thickness of the substrate cut is 0.5-1 mm.

[0015] Compared with the prior art, the present invention can at least achieve one of the following beneficial effects: (1) Through the synergistic effect of nano beryllium oxide, magnesium aluminum silicate and nano silicon dioxide and specific proportions, the present invention realizes the improvement of the bulk density, thermal conductivity and flexural strength of the beryllium oxide ceramic substrate and the reduction of the grain size; (2) The raw materials of the present invention also include a small amount of nano yttrium oxide. The nano yttrium oxide particles can be evenly dispersed in the beryllium oxide matrix, and the grain boundary migration is inhibited through physical pinning effect to prevent abnormal grain growth. Y2O3 forms a low melting point eutectic phase (such as Y-Si-Al-O glass phase) with MgO, Al2O3 and SiO2 in magnesium aluminum silicate at high temperature, promotes densification sintering, and at the same time inhibits grain coarsening driven by surface diffusion by liquid phase wrapping grains. Y2O3 can react with nano SiO2 to generate high-temperature resistant silicates such as Y2Si2O7, further enhancing the grain boundary stability and delaying the grain growth kinetics. The performance of the beryllium oxide substrate prepared by adding nano yttrium oxide to the raw materials of the present invention is better; (3) The bulk density of the fine-grained beryllium oxide ceramic film substrate is 2.913 - 2.929 g / cm 3 , the thermal conductivity (25°C) ≥ 282 W / m·K, preferably 282 - 308 W / m·K, the flexural strength at room temperature ≥ 240 MPa, preferably 243 - 263 MPa, the average grain size ≤ 10 μm, preferably 7.9 - 9.9 μm, and the surface roughness after polishing ≤ 0.041 μm, preferably 0.013 - 0.041 μm; (4) The method of the present invention replaces the sintering after dry isostatic pressing in the prior art with direct hot pressing sintering. Combined with the specific raw materials and ratios of the present invention, the densification of the fine-grained beryllium oxide ceramic film substrate is improved, the grain size is smaller, and the sintering temperature of the method of the present invention is reduced.

[0016] In the present invention, the above technical solutions can also be combined with each other to achieve more preferred combination schemes. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can be made obvious from the description, or understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained from the content specifically pointed out in the description and the drawings. Description of the Drawings

[0017] The drawings are only for the purpose of showing specific embodiments and are not considered as limiting the present invention. Throughout the drawings, the same reference signs represent the same components; Figure 1 It is a grain size diagram of the fine-grained beryllium oxide ceramic film substrate prepared in Example 1 of the present invention. Detailed Embodiments

[0018] The following will specifically describe the preferred embodiments of the present invention with reference to the drawings. Among them, the drawings form a part of the present invention and are used together with the embodiments of the present invention to explain the principle of the present invention, and are not used to limit the scope of the present invention.

[0019] In a specific embodiment of the present invention, a fine-grained beryllium oxide ceramic film substrate is disclosed. By weight, the raw materials of the substrate include 99 - 99.5 parts of nano beryllium oxide (for example, 99.1 parts, 99.2 parts, 99.3 parts, 99.4 parts), 0.2 - 0.5 parts of magnesium aluminum silicate (for example, 0.22 parts, 0.24 parts, 0.26 parts, 0.28 parts, 0.30 parts, 0.32 parts, 0.34 parts, 0.36 parts, 0.38 parts, 0.40 parts, 0.42 parts, 0.44 parts, 0.46 parts, 0.48 parts), and 0.2 - 0.3 parts of nano silicon dioxide (for example, 0.22 parts, 0.24 parts, 0.26 parts, 0.28 parts).

[0020] The beryllium oxide substrate of the present invention uses nano beryllium oxide, magnesium aluminum silicate and nano silicon dioxide to act synergistically, improving the thermal conductivity and flexural strength of the substrate and reducing the grain size. Among them, nano beryllium oxide has high sintering activity, and through surface energy-driven rapid diffusion, a matrix with low porosity is formed. The nano-particle size is small, and the grain boundaries hinder the dislocation movement, significantly improving the flexural strength. The interface reaction between nano beryllium oxide and magnesium aluminum silicate and nano silicon dioxide is controllable at high temperatures, avoiding the formation of brittle phases. In the structure of magnesium aluminum silicate, the Mg, Al, and Si atoms are bonded, and are gradually released at high temperatures. Magnesium aluminum silicate forms a low-melting-point glass phase, filling the gaps between BeO particles, driving particle rearrangement through capillary force, reducing porosity, and synergistically with nano BeO to improve thermal conductivity and strength. In addition, magnesium aluminum silicate and nano silicon dioxide can also reduce the sintering temperature. Nano silicon dioxide fills the micropores and microcracks at the grain boundaries of nano beryllium oxide, reducing phonon scattering sites, and synergistically with nano beryllium oxide to optimize the thermal conductivity. Magnesium aluminum silicate can also inhibit the abnormal growth of nano beryllium oxide grains and maintain a fine and uniform microstructure.

[0021] In summary, the synergistic effect of nano beryllium oxide, magnesium aluminum silicate and nano silicon dioxide, as well as a specific ratio, have achieved an increase in the bulk density, thermal conductivity, flexural strength and a decrease in the grain size of the beryllium oxide ceramic substrate. The purity of the fine-grained beryllium oxide ceramic thin film substrate of the present invention can reach more than 99%.

[0022] Specifically, the raw materials further include 0.1-0.2 parts of nano yttrium oxide.

[0023] It should be noted that the raw materials of the present invention also include a small amount of nano yttrium oxide (Y2O3). The nano yttrium oxide particles can be evenly dispersed in the beryllium oxide matrix, inhibiting grain boundary migration through physical pinning and preventing abnormal grain growth. Y2O3 forms a low-melting-point eutectic phase (such as Y-Si-Al-O glass phase) with MgO, Al2O3 and SiO2 in magnesium aluminum silicate at high temperatures, promoting densification sintering, and at the same time inhibiting grain coarsening driven by surface diffusion by liquid-phase encapsulation of grains. Y2O3 can react with nano SiO2 to generate high-temperature-resistant silicates such as Y2Si2O7, further enhancing the grain boundary stability and delaying the grain growth kinetics. The performance of the substrate prepared by adding nano yttrium oxide to the raw materials of the present invention is better.

[0024] Specifically, the particle size of the nano-beryllium oxide is 20-100 nm (for example, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm), the particle size of the magnesium aluminum silicate is 0.5-1 μm (for example, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm), the particle size of the nano-silicon dioxide is 10-30 nm (for example, 12 nm, 14 nm, 16 nm, 18 nm), and the particle size of the nano-yttrium oxide is 30-40 nm (for example, 32 nm, 34 nm, 36 nm, 38 nm).

[0025] It should be noted that if the particle size of the nano-beryllium oxide is too small, the porosity decreases, and abnormal grain growth is likely to occur during sintering. If the particle size is too large, the sintering activity decreases, pores are likely to remain, the thermal conductivity decreases, and at the same time, the grain coarsening reduces the flexural strength.

[0026] If the particle size of the magnesium aluminum silicate is too small, the thermal conductivity decreases and cracks are likely to appear. If the particle size is too large, pores or weak interfacial regions will be formed, which is likely to lead to brittle interfacial phases.

[0027] If the particle size of the nano-silicon dioxide is too small, the high surface energy leads to agglomeration. If the particle size is too large, only micron-sized defects can be repaired, and the surface smoothing effect is weakened.

[0028] When the particle size of the nano-yttrium oxide is within the above range, comprehensive optimization of grain refinement, smooth surface, controllable reduction of thermal conductivity and strength improvement can be achieved.

[0029] Specifically, the surface roughness of the fine-grained beryllium oxide ceramic thin film substrate is ≤0.05 μm.

[0030] Specifically, the bulk density of the fine-grained beryllium oxide ceramic thin film substrate is 2.913-2.929 g / cm 3 , the thermal conductivity (25 °C) ≥282 W / m·K, preferably 282-308 W / m·K, the room temperature flexural strength ≥240 MPa, preferably 243-263 MP, the average grain size ≤10 μm, preferably 7.9-9.9 μm, and the surface roughness after polishing is ≤0.041 μm, preferably 0.013-0.041 μm.

[0031] Another specific embodiment of the present invention discloses a preparation method of the above-mentioned fine-grained beryllium oxide ceramic thin film substrate, which includes the following steps: (1) Weigh and set aside according to the weight parts of each raw material; (2) Dissolve polyvinyl alcohol in water to obtain solution A; (3) Add the set-aside raw materials to water, stir and grind to obtain a beryllium oxide slurry; (4) Add the said Solution A to the said beryllium oxide slurry, stir, granulate and dry to obtain granulated powder; (5) Subject the said granulated powder to hot press sintering, cut it into substrates, and sequentially subject the two sides of the said substrates to thinning, grinding and polishing treatments to obtain the said fine-grained beryllium oxide ceramic thin film substrate.

[0032] Specifically, in step (2), the mass ratio of polyvinyl alcohol to water is 10-20:100 (for example, 11:100, 12:100, 13:100, 14:100, 15:100, 16:100, 17:100, 18:100, 19:100).

[0033] Specifically, in step (3), the mass ratio of the total mass of the spare raw materials to the mass of water is 20-54 (for example, 22, 24, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52): 46-50 (for example, 47, 48, 49).

[0034] Preferably, the grinding is carried out by circulating grinding with a sand mill for 30-60 min (for example, 35 min, 40 min, 45 min, 50 min, 55 min) to eliminate agglomerates. If the ball milling time is too short, the agglomerates in the slurry are difficult to eliminate and the particle size distribution is relatively wide. If the ball milling time is too long, the wear of the ball milling medium increases and enters the beryllium oxide slurry, affecting the purity and performance of beryllium oxide.

[0035] Specifically, in step (4), the mass ratio of the said beryllium oxide slurry to Solution A is 100:3-5 (100:3.2, 100:3.4, 100:3.6, 100:3.8, 100:4.0, 100:4.2, 100:4.4, 100:4.6, 100:4.8).

[0036] It should be noted that if the addition of the polyvinyl alcohol solution is too low, the granulated particles are fine and the fluidity of the powder is poor. If the addition of the polyvinyl alcohol solution is too much, micropores are formed after volatilization during the sintering process, affecting the density of the ceramic.

[0037] Specifically, in step (4), the stirring time ≥ 2 h.

[0038] Specifically, in step (4), the average particle size of the said granulated powder is 50-80 μm, for example, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm.

[0039] It should be noted that if the particle size of the granulated powder is too small, its fluidity is poor, making it difficult to uniformly fill the mold, which easily leads to voids and low density. Granulated powder with too large a particle size will result in a reduced contact area between particles during the sintering process, affecting the density and strength of the sintered body. Large particles are difficult to achieve an ideal densification effect during sintering, which may lead to a decline in product performance.

[0040] Specifically, in step (5), the sintering temperature of the hot-press sintering is 1600 - 1650 °C, for example, 1605 °C, 1610 °C, 1615 °C, 1620 °C, 1625 °C, 1630 °C, 1635 °C, 1640 °C, 1645 °C, the pressure is 20 - 30 MPa, for example, 22 MPa, 24 MPa, 26 MPa, 28 MPa, and the heat preservation time is 10 - 30 min, 12 min, 14 min, 16 min, 18 min, 20 min, 22 min, 24 min, 26 min, 28 min.

[0041] The method of the present invention replaces the sintering after dry isostatic pressing in the prior art with direct hot-press sintering. Combined with the specific raw materials and ratios of the present invention, it improves the density of the fine-grained beryllium oxide ceramic thin film substrate, with smaller grain sizes, and the method of the present invention reduces the sintering temperature.

[0042] It should be noted that due to too high a sintering temperature, obvious grain growth occurs, the number of grain boundaries increases, which hinders heat conduction, reduces the thermal conductivity, defects are generated inside the material, cracks are produced, the flexural strength is reduced, the grain growth is uneven, the surface is uneven, and the surface roughness increases. Within the pressure range of the present invention, the beryllium oxide powder particles can be made closer, the pores are reduced, the density is increased, and the thermal conductivity is improved. Excessive pressure will cause abnormal grain growth, reduce the thermal conductivity, uneven stress on the grains due to excessive pressure, generate defects, reduce the flexural strength, and excessive pressure will cause particle rupture, uneven surface, resulting in an increase in surface roughness. Too long a sintering time will lead to excessive grain growth, increased grain boundary scattering, decreased thermal conductivity, coarse grains, generation of defects, reduced flexural strength, and the surface may also be uneven due to grain growth.

[0043] In summary, only by adopting the sintering temperature of 1600 - 1650 °C, pressure of 20 - 30 MPa, and heat preservation time of 10 - 30 min of the present invention can the fine-grained beryllium oxide ceramic thin film substrate have a higher density and higher flexural strength. In addition, the present invention adopts the method of hot-press rapid sintering, which reduces the sintering temperature and has a short heat preservation time, and can effectively reduce the grain size.

[0044] Specifically, in step (5), it is cut into a substrate by a diamond wire cutting machine. Preferably, the thickness of the substrate is 0.5 - 1 mm, for example, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm.

[0045] Grinding is carried out using a double-sided grinding machine, which is equipped with a W20 diamond grinding pad and W10 diamond grinding fluid. The thick plate is processed by multi-wire cutting. Compared with single-piece processing, the processing allowance is greatly reduced, materials are saved, and costs are lowered.

[0046] It should be noted that in step (5), polishing is carried out using a polishing machine and polishing fluid. Rough polishing and fine polishing are carried out in sequence. After polishing, the surface roughness is ≤0.05μm.

[0047] The so-called rough polishing is carried out on a rough polishing disc. The rough polishing allowance is 0.01mm - 0.015mm. For example, 0.011mm, 0.012mm, 0.013mm, 0.014mm. Rough polishing is carried out using JX0750 polishing fluid. The rotation speed of the polishing disc is 60 - 70rpm. For example, 62rpm, 64rpm, 66rpm, 68rpm. The rough polishing time is 1 - 5min. For example, 2min, 3min, 4min.

[0048] The so-called fine polishing is carried out on a fine polishing disc. The fine polishing allowance is 0.001mm - 0.002mm. For example, 0.0012mm, 0.0014mm, 0.0016mm, 0.0018mm. Fine polishing is carried out using JX2000 polishing fluid. The rotation speed of the polishing disc is 60 - 70rpm. For example, 62rpm, 64rpm, 66rpm, 68rpm. The fine polishing time is 60 - 70min. For example, 62min, 64min, 66min, 68min.

[0049] The manufacturers of JX0750 polishing fluid and JX2000 polishing fluid in the present invention are Guizhou Jinte Grinding Technology Development Co., Ltd.

[0050] Through specific raw materials, ratios and preparation methods, the present invention uses polyvinyl alcohol as a binder, grinding slurry, granulation and drying, etc., to improve the uniformity and density of the material, thereby significantly enhancing the thermal conductivity, flexural strength and surface roughness; adopting a hot pressing and sintering process, through the combined action of high temperature and high pressure, promotes the diffusion and combination between particles, and further improves the performance of the material. The optimization of this process significantly improves the density and strength of the material, while inhibiting the excessive growth of grains and avoiding the performance degradation caused by coarse grains.

[0051] The preparation method of the present invention significantly improves the thermal conductivity, flexural strength and reduces the surface roughness of the fine-grained beryllium oxide ceramic thin film substrate by optimizing the raw material ratio, processing steps and sintering process.

[0052] The thickness of the fine-grained beryllium oxide ceramic thin film substrate obtained by the method of the present invention is 0.381 ± 0.005 mm to 0.762 ± 0.005 mm.

[0053] It should be noted that all raw materials in the present invention are commercially available raw materials. The technical solution of the present invention will be further explained and illustrated below in combination with specific embodiments.

[0054] Example 1 A fine-grained beryllium oxide ceramic thin film substrate of this example, by weight, the raw materials of the fine-grained beryllium oxide ceramic thin film substrate include 99.5 parts of nano beryllium oxide, 0.2 parts of magnesium aluminum silicate, and 0.3 parts of nano silicon dioxide.

[0055] Among them, the particle size of the nano beryllium oxide is 60 nm, the particle size of the magnesium aluminum silicate is 0.75 μm, and the particle size of the nano silicon dioxide is 30 nm.

[0056] The preparation method of the fine-grained beryllium oxide ceramic thin film substrate of this example includes the following steps: (1) Weigh and set aside according to the weight parts of each raw material; (2) Dissolve polyvinyl alcohol in water, and the mass ratio of polyvinyl alcohol to water is 20:100 to obtain solution A; (3) Add the reserved nano beryllium oxide, magnesium aluminum silicate, and nano silicon dioxide to water. The total mass ratio of nano beryllium oxide, magnesium aluminum silicate, and nano silicon dioxide to water is 50:50. Stir and grind with a sand mill for 30 min to eliminate agglomerates to obtain beryllium oxide slurry; (4) Add the solution A to the beryllium oxide slurry. The volume ratio of the beryllium oxide slurry to the solution A is 100:5. Stir for ≥ 2 h, granulate and dry to obtain granulated powder, and the particle size of the granulated powder is 65 μm; (5) Hot press sinter the granulated powder at a hot press sintering temperature of 1625 °C, a pressure of 25 Mpa, and a heat preservation time of 20 min to obtain a beryllium oxide thick plate with a thickness of 10 - 15 mm. Cut the thick plate into thin substrates using a diamond wire cutting machine. The thickness of the thin substrate is 0.75 mm. Then, use a double-sided grinding machine to reduce the thickness. The grinding machine is equipped with a W20 diamond grinding pad and W10 diamond grinding fluid to obtain a fine-grained beryllium oxide ceramic substrate with a thickness of 0.65 mm. Further, polish the substrate using a polishing machine with a polishing fluid, and perform rough polishing and fine polishing in sequence. After polishing, the surface roughness is ≤0.05 μm. The rough polishing is carried out on a rough polishing disc with a rough polishing amount of 0.013 mm. The rough polishing uses JX0750 polishing fluid for polishing, the polishing disc rotates at 65 rpm, and the rough polishing time is 3.5 min. The fine polishing is carried out on a fine polishing disc with a fine polishing allowance of 0.0015 mm. The fine polishing uses JX2000 polishing fluid for polishing, the polishing disc rotates at 65 rpm, and the fine polishing time is 65 min to obtain the fine-grained beryllium oxide ceramic thin film substrate with a thickness of 0.635 ± 0.005 mm.

[0057] The grain size of the fine-grained beryllium oxide ceramic thin film substrate prepared in this example is as Figure 1 shown.

[0058] Example 2 A fine-grained beryllium oxide ceramic thin film substrate in this example, by weight, the raw materials of the fine-grained beryllium oxide ceramic thin film substrate include: 99.25 parts of nano beryllium oxide, 0.5 part of magnesium aluminum silicate, and 0.25 part of nano silicon dioxide.

[0059] Among them, the particle size of the nano beryllium oxide is 20 nm, the particle size of the magnesium aluminum silicate is 1 μm, and the particle size of the nano silicon dioxide is 20 nm. The preparation method of the fine-grained beryllium oxide ceramic thin film substrate in this example includes the following steps: (1) Weigh and set aside according to the weight parts of each raw material; (2) Dissolve polyvinyl alcohol in water with a mass ratio of polyvinyl alcohol to water of 15:100 to obtain solution A; (3) Add the reserved nano beryllium oxide, magnesium aluminum silicate, and nano silicon dioxide to water with a total mass ratio of nano beryllium oxide, magnesium aluminum silicate, and nano silicon dioxide to water of 20:46. Stir and grind using a sand mill for 45 min to eliminate agglomerates to obtain a beryllium oxide slurry; (4) Add the solution A to the beryllium oxide slurry with a volume ratio of the beryllium oxide slurry to solution A of 100:4. Stir for ≥2 h, granulate and dry to obtain granulated powder with a granulated powder particle size of 65 μm; (5) Hot press sinter the granulated powder at a hot press sintering temperature of 1600 °C, a pressure of 20 Mpa, and a heat preservation time of 30 min to obtain a beryllium oxide thick plate with a thickness of 10 - 15 mm. Use a diamond wire cutting machine to cut the thick plate into thin substrates with a thickness of 0.62 mm. Then use a double-sided grinding machine to reduce the thickness. The grinding machine is equipped with a W20 diamond grinding pad and W10 diamond grinding fluid to obtain a fine-grained beryllium oxide ceramic substrate with a thickness of 0.52 mm. Further, use a polishing machine to polish with a polishing fluid, and perform rough polishing and fine polishing in sequence. After polishing, the surface roughness is ≤0.05 μm. The rough polishing is carried out on a rough polishing disc with a rough polishing processing amount of 0.01 mm. The rough polishing uses JX0750 polishing fluid for polishing, the polishing disc rotates at 60 rpm, and the rough polishing time is 1 min. The fine polishing is carried out on a fine polishing disc with a fine polishing allowance of 0.001 mm. The fine polishing uses JX2000 polishing fluid for polishing, the polishing disc rotates at 60 rpm, and the fine polishing time is 70 min to obtain the fine-grained beryllium oxide ceramic thin film substrate with a thickness of 0.508 ± 0.005 mm.

[0060] Example 3 For a fine-grained beryllium oxide ceramic thin film substrate of this example, by weight, the raw materials of the fine-grained beryllium oxide ceramic thin film substrate include: 99 parts of nano beryllium oxide, 0.3 parts of magnesium aluminum silicate, and 0.3 parts of nano silicon dioxide.

[0061] Among them, the particle size of the nano beryllium oxide is 100 nm, the particle size of the magnesium aluminum silicate is 0.5 μm, and the particle size of the nano silicon dioxide is 10 nm.

[0062] The preparation method of the fine-grained beryllium oxide ceramic thin film substrate of this example includes the following steps: (1) Weigh and set aside according to the weight parts of each raw material; (2) Dissolve polyvinyl alcohol in water with a mass ratio of polyvinyl alcohol to water of 10:100 to obtain solution A; (3) Add the set-aside nano beryllium oxide, magnesium aluminum silicate, and nano silicon dioxide to water with a mass ratio of the total mass of nano beryllium oxide, magnesium aluminum silicate, and nano silicon dioxide to water of 37:48. Stir and grind with a sand mill in a cycle for 60 min to eliminate agglomerates and obtain a beryllium oxide slurry; (4) Add the solution A to the beryllium oxide slurry with a volume ratio of the beryllium oxide slurry to solution A of 100:3. Stir for a time ≥2 h, granulate and dry to obtain granulated powder with a granulated powder particle size of 65 μm; (5) Hot press sinter the granulated powder at a hot press sintering temperature of 1650 °C, a pressure of 30 Mpa, and a heat preservation time of 10 min to obtain a beryllium oxide thick plate with a thickness of 10 - 15 mm. Cut the thick plate into thin substrates using a diamond wire cutting machine. The thickness of the thin substrate is 0.88 mm. Then, use a double-sided grinding machine to reduce the thickness. The grinding machine is equipped with a W20 diamond grinding pad and W10 diamond grinding fluid to obtain a fine-grained beryllium oxide ceramic substrate with a thickness of 0.78 mm. Further, use a polishing machine to polish with a polishing fluid, and perform rough polishing and fine polishing in sequence. After polishing, the surface roughness ≤ 0.05 μm. The rough polishing is carried out on a rough polishing disc, the rough polishing machining amount is 0.015 mm, the rough polishing uses JX0750 polishing fluid for polishing, the polishing disc rotation speed is 70 rpm, and the rough polishing time is 5 min. The fine polishing is carried out on a fine polishing disc, the fine polishing machining allowance is 0.002 mm, the fine polishing uses JX2000 polishing fluid for polishing, the polishing disc rotation speed is 70 rpm, and the fine polishing time is 60 min to obtain the fine-grained beryllium oxide ceramic thin film substrate with a thickness of 0.762 ± 0.005 mm.

[0063] Example 4 For a fine-grained beryllium oxide ceramic thin film substrate of this example, by weight, the raw materials of the fine-grained beryllium oxide ceramic thin film substrate include: 99.2 parts of nano beryllium oxide, 0.5 parts of magnesium aluminum silicate, and 0.3 parts of nano silicon dioxide.

[0064] Among them, the particle size of the nano beryllium oxide is 35 nm, the particle size of the magnesium aluminum silicate is 0.85 μm, and the particle size of the nano silicon dioxide is 25 nm.

[0065] The preparation method of the fine-grained beryllium oxide ceramic thin film substrate of this example includes the following steps: (1) Weigh and set aside according to the weight parts of each raw material; (2) Dissolve polyvinyl alcohol in water, and the mass ratio of polyvinyl alcohol to water is 13:100 to obtain solution A; (3) Add the set-aside nano beryllium oxide, magnesium aluminum silicate, and nano silicon dioxide into water. The total mass ratio of nano beryllium oxide, magnesium aluminum silicate, and nano silicon dioxide to water is 54:46. Stir and grind using a sand mill for 50 min to eliminate agglomerates to obtain a beryllium oxide slurry; (4) Add the solution A to the beryllium oxide slurry. The volume ratio of the beryllium oxide slurry to solution A is 100:3.5. Stir for ≥ 2 h, granulate and dry to obtain granulated powder with a particle size of 65 μm; (5) Hot press sinter the granulated powder at a hot press sintering temperature of 1610 °C, a pressure of 28 Mpa, and a heat preservation time of 15 min to obtain a beryllium oxide thick plate with a thickness of 10 - 15 mm. Cut the thick plate into thin substrates using a diamond wire cutting machine. The thickness of the thin substrate is 0.5 mm. Then, further reduce the thickness using a double-sided grinding machine equipped with a W20 diamond grinding pad and W10 diamond grinding fluid to obtain a fine-grained beryllium oxide ceramic substrate with a thickness of 0.4 mm. Further polish the substrate using a polishing machine with a polishing fluid, performing rough polishing and fine polishing in sequence. After polishing, the surface roughness is ≤0.05 μm. The rough polishing is carried out on a rough polishing disc with a rough machining amount of 0.012 mm. The rough polishing uses JX0750 polishing fluid, the polishing disc rotates at 63 rpm, and the rough polishing time is 2.5 min. The fine polishing is carried out on a fine polishing disc with a fine machining allowance of 0.0018 mm. The fine polishing uses JX2000 polishing fluid, the polishing disc rotates at 63 rpm, and the fine polishing time is 67 min to obtain the fine-grained beryllium oxide ceramic thin film substrate with a thickness of 0.381 ± 0.005 mm.

[0066] Example 5 The raw materials and preparation method of a fine-grained beryllium oxide ceramic thin film substrate in this example are the same as those in Example 1, except that the raw materials further include 0.15 parts of nano-yttrium oxide with a particle size of 35 nm, and the nano-yttrium oxide is added in step (3) of the preparation method.

[0067] Example 6 The raw materials and preparation method of a fine-grained beryllium oxide ceramic thin film substrate in this example are the same as those in Example 1, except that the raw materials further include 0.1 parts of nano-yttrium oxide with a particle size of 30 nm, and the nano-yttrium oxide is added in step (3) of the preparation method.

[0068] Example 7 The raw materials and preparation method of a fine-grained beryllium oxide ceramic thin film substrate in this example are the same as those in Example 1, except that the raw materials further include 0.2 parts of nano-yttrium oxide with a particle size of 40 nm, and the nano-yttrium oxide is added in step (3) of the preparation method.

[0069] Comparative Example 1 The raw materials and preparation method of a beryllium oxide ceramic substrate in this comparative example are the same as those in Example 1, except that the aluminum magnesium silicate in the raw materials is replaced with magnesium silicate.

[0070] Comparative Example 2 The raw materials and preparation method of a beryllium oxide ceramic substrate in this comparative example are the same as those in Example 1, except that the aluminum magnesium silicate in the raw materials is replaced with alumina.

[0071] Comparative Example 3 The raw materials of a beryllium oxide ceramic substrate in this comparative example and its preparation method are the same as those in Example 1, except that magnesium aluminum silicate in the raw materials is replaced by magnesium oxide.

[0072] Comparative Example 4 The raw materials of a beryllium oxide ceramic substrate in this comparative example and its preparation method are the same as those in Example 1, except that the weight part of magnesium aluminum silicate is 0.2 parts.

[0073] Comparative Example 5 The raw materials of a beryllium oxide ceramic substrate in this comparative example and its preparation method are the same as those in Example 1, except that in step (5) of the preparation method, hot press sintering is replaced by directly putting the granulated powder into a mold, pressing and forming under a pressure of 25 MPa, and sintering at a sintering temperature of 1625 °C for 20 min.

[0074] Comparative Example 6 The raw materials of a beryllium oxide ceramic substrate in this comparative example and its preparation method are the same as those in Example 1, except that in step (5) of the preparation method, the sintering temperature is 1700 °C and the pressure is 35 MPa.

[0075] Comparative Example 7 The raw materials of a beryllium oxide ceramic substrate in this comparative example and its preparation method are the same as those in Example 1, except that the particle size of nano beryllium oxide in the raw materials is replaced by 15 nm.

[0076] Comparative Example 8 The raw materials of a beryllium oxide ceramic substrate in this comparative example and its preparation method are the same as those in Example 1, except that the particle size of magnesium aluminum silicate in the raw materials is replaced by 1.2 μm.

[0077] Comparative Example 9 The raw materials of a beryllium oxide ceramic substrate in this comparative example and its preparation method are the same as those in Example 1, except that magnesium aluminum silicate in the raw materials is replaced by SiO2, MgO and Al2O3, and the molar ratio of silicon, magnesium and aluminum remains unchanged.

[0078] Test Example 1 The bulk density of the substrates prepared in Examples 1-7 and Comparative Examples 1-9 was measured respectively, and the thermal conductivity, room temperature flexural strength, average grain size and surface roughness after polishing were measured according to the requirements of GJB 3522A-2011 standard at 25 °C. The results are shown in Table 1.

[0079] ; As shown in the above table, when Examples 5-7 are compared with Examples 1-4, after nano yttrium oxide is added to the raw materials, the performance of the prepared substrates is significantly better than that of the substrates without adding nano yttrium oxide. Compared with Example 1, Comparative Examples 1-9 have poorer performance, indicating that only the substrates prepared under the conditions of the present invention have better performance.

[0080] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A fine-grained beryllium oxide ceramic thin film substrate, characterized in that, By weight parts, the raw materials of the substrate include: beryllium oxide nanometer: 99 - 99.5 parts, magnesium aluminum silicate: 0.2 - 0.5 parts, silicon dioxide nanometer: 0.2 - 0.3 parts.

2. The fine-grained beryllium oxide ceramic thin film substrate according to claim 1, characterized in that The raw materials further include yttrium oxide nanometer: 0.1 - 0.2 parts.

3. The fine-grained beryllium oxide ceramic thin film substrate according to claim 2, wherein The particle size of the beryllium oxide nanometer is 20 - 100 nm, the particle size of the magnesium aluminum silicate is 0.5 - 1 μm, the particle size of the silicon dioxide nanometer is 10 - 30 nm, and the particle size of the yttrium oxide nanometer is 30 - 40 nm.

4. A method for preparing a fine-grained beryllium oxide ceramic thin film substrate according to any one of claims 1-3, characterized in that, It includes the following steps: (1) Weigh and set aside respectively according to the weight parts of each raw material; (2) Dissolve polyvinyl alcohol in water to obtain solution A; (3) Add the set - aside raw materials into water, stir and grind to obtain beryllium oxide slurry; (4) Add the solution A into the beryllium oxide slurry, stir, spray granulation and dry to obtain granulated powder; (5) Carry out hot - press sintering on the granulated powder, cut it into a substrate, and subject the two sides of the substrate to thinning grinding and polishing treatment in sequence to obtain the fine - grained beryllium oxide ceramic thin - film substrate.

5. The preparation method according to claim 4, characterized in that, In step (2), the mass ratio of polyvinyl alcohol to water is 10 - 20:

100.

6. The preparation method according to claim 4, characterized in that, In step (3), the mass ratio of the total mass of the set - aside raw materials to water is 20 - 54:46 - 50.

7. The preparation method according to claim 4, characterized in that, In step (4), the mass ratio of the beryllium oxide slurry to solution A is 100:3 - 5.

8. The preparation method according to claim 4, wherein In step (4), the stirring time is ≥2 h, and the average particle size of the granulated powder is 50 - 80 μm.

9. The preparation method according to claim 4, characterized in that, The sintering temperature of the hot - press sintering is 1600 - 1650 °C, the pressure is 20 - 30 MPa, and the heat - preservation time is 10 - 30 min.

10. The preparation method according to claim 4, characterized in that, In step (5), the thickness of the cut substrate is 0.5 - 1 mm.

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