An easily processed high-performance ceramic substrate and its preparation method

Abstract

This invention discloses an easily machinable high-performance ceramic substrate and its preparation method, relating to the field of ceramic substrate processing and manufacturing technology. The invention provides a preparation method in which a ceramic green body is subjected to low-temperature sintering, wire sawing, high-temperature heat treatment, and finally grinding and polishing to obtain a high-performance ceramic substrate. Specifically, by controlling the temperature and time of low-temperature sintering, the density of the obtained sintered ceramic block can be controlled to be 50-95% of the theoretical density, the flexural strength to be 20%-85% of the finished product, and the hardness (HV) to be 1.5-12 GPa. The properties of this sintered ceramic block make it easier to perform wire sawing, significantly improving processing efficiency. Furthermore, this sintered ceramic body ensures that no cracking occurs when processing thin ceramic sheets (0.35-2 mm), avoiding defective products. The processed ceramic sheets can be further sintered to full or high density through high-temperature heat treatment, improving hardness, flexural strength, and thermal conductivity, achieving the performance requirements of the finished ceramic substrate.

Description

Technical Field

[0001] This invention relates to the field of ceramic substrate processing and manufacturing technology, and in particular to an easily processed high-performance ceramic substrate and its preparation method. Background Technology

[0002] Ceramic heat sinks play a crucial role in the heat dissipation, insulation protection, and structural packaging support of various electronic components. They are vital to the safety and reliability of electronic devices during operation, therefore, ceramic substrates need to possess high strength and excellent thermal conductivity to meet lifespan requirements. Currently, Al2O3, AlN, Si3N4, and SiC are widely used or promising ceramic substrate materials. Besides tape casting, another method for manufacturing these thin-sheet ceramic materials is to first sinter the ceramic to achieve density, then use wire sawing or a cutting machine to cut the ceramic material into thin sheets, followed by grinding and polishing. Compared to cutting machine machining, wire sawing has the advantage that the feed rate is not limited by the tool size, allowing for the cutting of thicker workpieces. Cutting machines, on the other hand, are limited by the tool design dimensions, with the maximum feed rate restricted to the tool's effective cutting depth.

[0003] The biggest problems with wire sawing currently are: First, during the sintering of large-size ceramics, the size effect easily causes uneven temperatures inside and outside the sample, resulting in density gradients, internal defects, and uneven distribution of residual thermal stress. Second, these high-temperature sintered ceramic materials generally have high flexural strength and high hardness (12-17 GPa), leading to low wire sawing efficiency and significant wear on diamond wire. A more serious problem is that ceramic substrates are prone to surface defects during wire sawing, such as microcracks, high-temperature burns, and bending deformation or even cracking due to uneven distribution of residual thermal stress. These surface defects significantly reduce the strength of the ceramic material, thereby shortening the lifespan of the substrate. Summary of the Invention

[0004] The technical problem to be solved by the present invention is that in the process of preparing large-size ceramic substrates by processing large-size ceramic sintered bodies with wire saw, the large-size ceramic sintered bodies have density gradients or internal defects due to uneven sintering temperature, and the high hardness and high bending strength of the ceramic sintered bodies lead to reduced efficiency of wire saw processing, large diamond wire wear, and easy generation of surface defects and bending deformation.

[0005] To address the above problems, the present invention proposes the following technical solution:

[0006] In a first aspect, the present invention provides a method for preparing an easily processed high-performance ceramic substrate, comprising the following steps:

[0007] S1. The ceramic powder is shaped and processed to obtain a ceramic blank;

[0008] S2. The ceramic blank is sintered to obtain a sintered ceramic block;

[0009] S3. The sintered ceramic block is wire-sawed to obtain ceramic sheets of a preset size;

[0010] S4. The ceramic sheet is subjected to high-temperature heat treatment, and then ground and polished to obtain a high-performance ceramic substrate.

[0011] The ceramic powder is any one of Al2O3, AlN, Si3N4, and SiC;

[0012] The temperature of the high-temperature heat treatment in step S4 is higher than the sintering temperature in step S2.

[0013] The high-temperature heat treatment time in step S4 is longer than the sintering time in step S2.

[0014] Furthermore, in step S2, the density of the ceramic sintered block is 50-95%, the flexural strength is 20-85% of the finished product's flexural strength, and the Vickers hardness is 1.5-12 GPa.

[0015] For example, in a specific implementation, in step S2, the density of the ceramic sintered block is 50%, 60%, 70%, 80%, or 90%, the flexural strength is 20%, 30%, 40%, 50%, 60%, 70%, or 80% of the finished product's flexural strength, and the Vickers hardness is 1.5 GPa, 2.5 GPa, 3.5 GPa, 4.5 GPa, 5.5 GPa, 6.5 GPa, 7.5 GPa, 8.5 GPa, 9.5 GPa, 10.5 GPa, or 11.5 GPa.

[0016] Specifically, the flexural strength and Vickers hardness of sintered ceramic blocks vary depending on the type of ceramic powder used.

[0017] When the ceramic powder is Al2O3, the flexural strength of the Al2O3 ceramic sintered block is 100-300 MPa and the Vickers hardness is 1.5-12 GPa.

[0018] When the ceramic powder is AlN, the flexural strength of the AlN ceramic sintered block is 90-250 MPa and the Vickers hardness is 1.5-10 GPa.

[0019] When the ceramic powder is Si3N4, the flexural strength of the Si3N4 ceramic sintered block is 90-600 MPa and the Vickers hardness is 1.5-12 GPa.

[0020] When the ceramic powder is SiC, the flexural strength of the SiC ceramic sintered block is 100-250 MPa and the Vickers hardness is 1.5-12 GPa.

[0021] The ceramic sintered blocks with the above properties, due to their lower flexural strength and Vickers hardness, can ensure higher efficiency in diamond wire sawing while minimizing diamond wire loss.

[0022] Furthermore, the sintering process in step S2 is as follows:

[0023] When the ceramic powder is Al2O3, the sintering temperature is 900-1500℃, preferably 900-1300℃, and the holding time is 0.5-6 hours, preferably 0.5-4 hours, and more preferably 0.5-2 hours.

[0024] When the ceramic powder is AlN, the sintering temperature is 1300-1750℃, preferably 1300-1650℃, and the holding time is 0.5-6 hours, preferably 0.5-4 hours, and more preferably 0.5-2 hours.

[0025] When the ceramic powder is Si3N4, the sintering temperature is 1300-1750℃, preferably 1350-1550℃; the holding time is 0.5-6 hours, preferably 0.5-4 hours, and more preferably 0.5-2 hours.

[0026] When the ceramic powder is SiC, the sintering temperature is 1500-1800℃ and the holding time is 0.5-6 hours.

[0027] It should be noted that the sintering method in step S2 can be any ceramic sintering method, such as vacuum sintering, atmospheric pressure sintering, gas pressure sintering, hot pressing sintering, plasma sintering, or microwave sintering. Specifically, the pressure during hot pressing sintering is 20–60 MPa; the atmosphere pressure during gas pressure sintering is 1–10 MPa. The specific sintering atmosphere used is one or both of N2 and Ar; particularly, hot pressing sintering, plasma sintering, and vacuum sintering can maintain a vacuum level of 10. -5 ~10 -2 Pa without using a protective atmosphere; in addition, Al2O3 ceramics can be sintered in an air atmosphere.

[0028] Further, in step S3, the wire sawing specifically refers to using a multi-wire diamond wire saw to process the sintered ceramic block into 2 to N ceramic sheets close to the finished product size. The dimensions of the processed ceramic sheets are: length 50 to 200 mm, width 40 to 200 mm, and thickness 0.35 to 2 mm; wire feed speed 1 to 60 m / s, wire diameter 0.1 to 0.6 mm is optimal; feed rate 0.1 to 30 mm / min; the cutting fluid used is an organic / inorganic solvent, or an appropriate amount of abrasive is added to the cutting fluid. The multi-wire diamond wire saw cutting used includes any other auxiliary processing methods, such as ultrasonic-assisted diamond wire saw cutting, electrostatic spray diamond wire saw cutting, diamond electrolytic grinding cutting, etc.

[0029] Understandably, the processing speed of multi-wire diamond wire saws is related to the mechanical properties of the material being processed. The higher the hardness and flexural strength of the material, the longer the cutting time and the greater the material consumption. This invention controls the properties of the sintered ceramic block by controlling the sintering temperature and time, resulting in a sintered ceramic block with a density of 50-95% of the theoretical density, a flexural strength of 20-85% of the finished product's flexural strength, and a Vickers hardness (HV) of 1.5-12 GPa. This sintered ceramic block meets the basic mechanical performance requirements for wire saw processing, ensuring that no cracking occurs during the processing of large-size, thin-thick ceramic sheets. Simultaneously, it reduces the mechanical properties of the material being processed, thereby reducing processing difficulty and improving processing efficiency.

[0030] Furthermore, in step S3, the thickness of the processed ceramic sheet will be 0.05 to 0.2 mm larger than that of the finished substrate. This is because the ceramic sheet will shrink after high-temperature heat treatment, and a certain processing allowance needs to be reserved for the ceramic sheet.

[0031] Furthermore, the high-temperature heat treatment process in step S4 is as follows:

[0032] When the ceramic powder is Al2O3, under an atmosphere of Ar, N2, or air, the pressure is 10. -5 The heat treatment is carried out under conditions of Pa to 300 MPa, with a heat treatment temperature of 1400 to 1700℃ and a holding time of 1 to 24 hours.

[0033] When the ceramic powder is AlN, the pressure is 10 in an Ar or N2 atmosphere. -5 The heat treatment is carried out under conditions of Pa to 300 MPa, with a heat treatment temperature of 1600 to 1900℃ and a holding time of 1 to 24 hours.

[0034] When the ceramic powder is Si3N4, the pressure is 10 in an Ar or N2 atmosphere. -5The heat treatment is carried out under conditions of Pa to 300 MPa, with a heat treatment temperature of 1700 to 2000℃ and a holding time of 1 to 24 hours.

[0035] When the ceramic powder is SiC, the pressure is 10 in an Ar or N2 atmosphere. -5 The heat treatment is carried out under conditions of Pa to 300 MPa, with a heat treatment temperature of 1800 to 2200℃ and a holding time of 1 to 24 hours.

[0036] In particular, when the ceramic powder is Al2O3, the heat treatment can be carried out in air at normal pressure, which can produce ceramic substrate blanks with dimensions close to the finished product size and high density.

[0037] This invention involves high-temperature heat treatment of ceramic sheets processed by wire sawing, which allows the ceramic sheets to be sintered to full or high density, ultimately meeting the performance requirements of the finished ceramic substrate. Furthermore, the ceramics acquire a higher sintering driving force at high temperatures, promoting ceramic particle rearrangement and densification. For example, Si3N4 ceramic powder and sintering aids form a liquid phase at high temperatures after high-temperature heat treatment, causing the ceramic grains to undergo particle rearrangement, dissolution-diffusion-reprecipitation, and grain growth again. This process can repair defects such as microcracks and high-temperature burns generated during wire sawing, improving the yield rate.

[0038] Furthermore, the grinding and polishing in step S4 can use sandpaper, diamond grinding discs, polishing discs, etc., with different grits. The grinding media can be inorganic solvents or various polishing agents, or abrasives can be added to them. The grinding material is selected based on the material's characteristics (mechanical properties, dimensional error, surface accuracy, etc.). Generally, larger grit processing tools (60-1000 grit) can be used in the initial grinding and polishing stage, while smaller grit processing tools (1000-2000 grit) can be used in subsequent finishing (surface accuracy <13μm). When the dimensional error is 100-200μm, 100-400 grit is preferred; when the dimensional error is 50-100μm, 400-800 grit is preferred; when the dimensional error is 13-50μm, 800-1000 grit is preferred; and when the dimensional error is <13μm, 1000-2000 grit is preferred.

[0039] Furthermore, between steps S3 and S4, the ceramic sheet is cleaned and dried. Processed ceramic sheets may retain processing debris and solvents. To avoid introducing impurities that could affect heat treatment and finished product performance, the processed ceramic sheet needs to be cleaned. Cleaning solvents can include deionized water, alcohol, propanol, etc., and ultrasonic cleaning can be used. After cleaning, the ceramic sheet also needs to be dried using an oven or vacuum dryer at a temperature of 50–300°C for 2–72 hours to avoid solvent residue.

[0040] Furthermore, step S1 also includes mixing the sintering aid with the ceramic powder, dry pressing, and cold isostatic pressing to obtain a ceramic blank.

[0041] Specifically, when the ceramic powder is Si3N4, the sintering aid can be one or more of CaO, Ce2O3, CeO2, Cr2O3, Dy2O3, Er2O3, Eu2O3, Gd2O3, HfN, HfO2, Ho2O3, MgO, Nd2O3, Pr2O3, PrO2, Sc2O3, SiC, SiO2, Sm2O3, Tb2O3, TiH2, Tm2O3, Y2O3, Yb2O3, ZnO, ZrO2, YF3, TiO2, MgSiN2, YbF3, BeO, and Y3Si2C2, and the particle size of the sintering aid is preferably 0.2–10 μm. The sintering aid accounts for 1-10% of the total mixed powder, the Si3N4 powder accounts for 90-99% of the total mixed powder, the original powder α-Si3N4 content is 90-99%, the Si3N4 particle size is preferably 0.5-1.5μm, the Fe impurity is less than 40ppm, and the O impurity content is less than 1%.

[0042] When the ceramic powder is AlN, the sintering aid is one or more of Y2O3, YF, CaF2, Yb2O3, B2O3, Sm2O3, CaO, BN, and Li2O. The particle size of the sintering aid is preferably 0.2–10 μm. The sintering aid accounts for 1–10% of the total mixed powder, AlN accounts for 90–99% of the total mixed powder, the AlN particle size is preferably 0.8–1.5 μm, Fe impurities are less than 40 ppm, and O impurities are less than 1%.

[0043] When the ceramic powder is Al2O3, the sintering aid is one or more of MgO, CaO, TiO2, La2O3, MnO2, SiO2, MgF2, BaO, ZrO2, Ce2O3, Nd2O5, and Y2O3, with the preferred particle size of the sintering aid being 0.2–10 μm. The sintering aid accounts for 1–10% of the total mixed powder, and the Al2O3 powder accounts for 90–99% of the total mixed powder, with the preferred Al2O3 particle size being 0.1–5.5 μm.

[0044] When the ceramic powder is SiC, the sintering aid is one or more of BeO, Y2O3, Gd2O3, Sc2O3, La2O3, TiN, AlN, BN, Sm2O3, YF3, MgO, Al2O3, Y3Si2C2, Gd3Si2C2, and Pr3Si2C2, with a preferred particle size of 0.2–10 μm. The sintering aid accounts for 1–10% of the total mixed powder, and the SiC powder accounts for 90–99% of the total mixed powder, with a preferred SiC particle size of 0.2–10 μm.

[0045] The specific steps for preparing ceramic green bodies by mixing sintering aids with ceramic powder, dry pressing, and cold isostatic pressing are as follows:

[0046] Uniform ceramic powder and sintering aid: The mixing method is usually ball milling. The ball milling process conditions are: horizontal rotation speed of 300 rpm to 400 rpm, vertical rotation speed of 5 rpm to 10 rpm, and ball milling time of 6 h to 12 h. The ball milling equipment includes an all-around planetary ball mill. The ball milling media is one or more of alumina, Si3N4, and zirconia balls. The ball-to-material ratio is 1:1 to 2. The mixed solvent is one or two of deionized water and anhydrous ethanol.

[0047] Dry the mixed powder and remove excess solvent: The drying method is usually rotary evaporation drying, with a rotary evaporation speed of 50-160 r / min, a drying temperature of 40-100℃, and a vacuum degree of 10Pa-101kPa, until the excess solvent is completely removed.

[0048] The dried mixed powder is sieved: the dried mixed powder is broken into block powder, and a 50-300 mesh sieve is used to control the particle size and improve the flowability of the powder;

[0049] Dry pressing and cold isostatic pressing: The pressure of dry pressing is 1-50 MPa and the holding time is 10-120 s; the pressure of cold isostatic pressing is 50-300 MPa and the holding time is 120-300 s.

[0050] Based on the above, a ceramic blank is obtained.

[0051] Secondly, the present invention provides a high-performance ceramic substrate, which is prepared by the method for preparing an easily processed high-performance ceramic substrate described in the first aspect. The ceramic substrate has a uniform color, no cutting marks, no cracks, and no regional defects.

[0052] In this invention, regional defects refer to the presence of holes or uneven density.

[0053] Thirdly, the present invention also provides a Si3N4 ceramic substrate, prepared by the method for preparing an easily processed high-performance ceramic substrate described in the first aspect, wherein the Raman spectral peak of the Si3N4 ceramic substrate is shifted to the left by 2 ± 0.5 cm. -1 Located at 520±2cm -1 The Si peak disappeared.

[0054] Compared with the prior art, the technical effects achieved by the present invention include:

[0055] This invention provides a method for preparing easily machinable high-performance ceramic substrates. The method involves sintering a ceramic blank to obtain a sintered ceramic block, wire sawing, high-temperature heat treatment, and finally grinding and polishing to obtain a high-performance ceramic substrate. The sintered ceramic block has a density of 50-95% of the theoretical density, a flexural strength of 20%-85% of the finished product's flexural strength, and a Vickers hardness (HV) of 1.5-12 GPa. This sintered ceramic block's properties make it easier to wire saw, reducing processing difficulty and significantly improving processing efficiency. Furthermore, this sintered ceramic body ensures that thin ceramic sheets (0.35-2 mm) will not crack during wire sawing, avoiding defective products. High-temperature heat treatment of the processed ceramic sheets allows for further sintering to full or high density, improving hardness, flexural strength, and thermal conductivity, ultimately meeting the performance requirements of the finished ceramic substrate. Furthermore, high-temperature heat treatment can repair surface microcracks and high-temperature burns generated during wire sawing, improving the yield rate. The ceramic substrates prepared by this method have relatively uniform microstructure, with no obvious color unevenness, no cutting marks, no cracks, and no regional defects (such as holes, uneven mass, etc.).

[0056] In particular, the Si3N4 ceramic substrate prepared according to the method of the present invention is characterized by a Raman spectral peak shifted to the left by 2 ± 0.5 cm⁻¹. -1 Located at 520±2cm -1 The Si peak disappeared.

[0057] In summary, the method for preparing easily machinable high-performance ceramic substrates provided by this invention can reduce the processing difficulty of ceramic substrates, reduce defects generated during processing, improve the yield of ceramic substrates, and reduce processing costs. The method of this invention is applicable to various ceramic substrate materials such as Al2O3, AlN, Si3N4, and SiC, and has good application prospects. Attached Figure Description

[0058] Figure 1 Comparison of Raman spectra of Si3N4 ceramic substrates prepared in Examples 13-16 and Example 20;

[0059] Figure 2 The image shows a comparison of the Raman spectrum peak values ​​of the Si3N4 ceramic substrates prepared in Examples 14 and 20.

[0060] Figure 3 Images showing quality problems encountered during the preparation of ceramic substrates in Examples 5, 10, and 20;

[0061] Figure 4 Images of the finished ceramic substrates obtained in Examples 3, 8, and 14. Detailed Implementation

[0062] The technical solutions in the embodiments will now be clearly and completely described with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0063] This invention provides a method for preparing easily machinable high-performance ceramic substrates, addressing the issues of uneven temperature distribution and density gradients caused by size effects during the sintering of large-size ceramics, leading to internal defects and uneven distribution of residual thermal stress. It also improves the efficiency of wire sawing of these ceramic materials, reduces diamond wire wear during processing, and minimizes surface defects generated during wire sawing, such as microcracks, high-temperature burns, and bending deformation or even cracking due to uneven distribution of residual thermal stress. Specific details of this invention are described below with reference to concrete embodiments.

[0064] Examples 1-4

[0065] This invention provides a method for preparing an easily processed, high-performance Al2O3 ceramic substrate, comprising the following steps:

[0066] (1) Powder selection

[0067] Al2O3 powder with a purity of 99.99% and a D50 of 0.33μm was used; Y2O3 with a purity of 99.9% and a sintering aid of 0.5μm was used. The experiment was conducted according to the formula of Al2O3:Y2O3 = 95:5 (mass ratio).

[0068] (2) Preparation of raw blank

[0069] Ball milling process: Weigh Al2O3 powder and sintering aid and place them in a polytetrafluoroethylene (PTFE) ball mill jar. The ball milling solvent is anhydrous ethanol, and the ball milling media is high-purity ZrO2 grinding balls. The ratio of powder raw material: anhydrous ethanol: ZrO2 grinding balls is 1:2:2 (mass ratio). Then, fix the PTFE ball mill jar in a planetary ball mill and ball mill for 6 hours at a horizontal speed of 350 rpm and a vertical speed of 10 rpm. After that, pour the mixed slurry into a flask of a rotary evaporator and perform rotary evaporation at a temperature of 60°C. Finally, sieve the dried powder through a 100-mesh sieve.

[0070] Dry pressing process: A certain amount of ceramic powder is weighed and placed in a 64mm×64mm mold. A bidirectional pressing method is used, applying a pressure of 8MPa in both directions of the mold and holding the pressure for 60s. After demolding, a dry-pressed ceramic green body is obtained. Then, the dry-pressed ceramic green body is vacuum-sealed in a vacuum sealing bag and placed in a cold isostatic press with a pressure of 200MPa. The pressure increase rate is 40MPa / min, and the pressure is held for 5min to finally obtain a cold isostatic pressed ceramic green body for subsequent sintering.

[0071] (3) Sintering

[0072] Atmospheric pressure sintering was performed in an air-filled atmosphere. The temperature was first increased to 800°C at a rate of 10°C / min, then increased to the sintering temperature at a rate of 5°C / min. After sintering, the temperature was decreased to 800°C at a rate of 5°C / min, and finally cooled to room temperature in the furnace to obtain the sintered ceramic block. Specific sintering process parameters and the properties of the sintered block are detailed in Examples 1-4 of Table 1.

[0073] (4) Diamond wire saw processing

[0074] The sintered ceramic block was machined using a diamond wire saw to obtain ceramic sheets with a thickness of 0.5 mm. The wire feed rate was 1.5 m / s, the wire diameter was 0.3 mm, and the feed rate was 0.2 mm / min. Water was used as the cutting fluid. After cutting, the sheets were cleaned using an ultrasonic cleaner with alcohol as the cleaning fluid. Subsequently, they were dried using a vacuum dryer at 60°C for 46 hours.

[0075] (5) High-temperature heat treatment

[0076] The ceramic sheet was subjected to high-temperature heat treatment in an air atmosphere at a pressure of 101 kPa. The temperature was first increased to 800°C at a rate of 10°C / min, then increased to 1600°C at a rate of 5°C / min and held for 2 hours. Subsequently, the temperature was decreased to 800°C at a rate of 5°C / min, and finally cooled to room temperature in the furnace to obtain a ceramic substrate blank. This blank was then ground and polished to obtain the ceramic substrate. The process parameters and sintered body properties are shown in Table 3.

[0077] Example 5

[0078] Example 5 served as the control group for Example 1, with identical formulation, powder, and preform preparation steps. The difference lay in the use of a conventional one-step sintering method, with sintering conditions identical to those in Example 1. The sintering process is shown in Table 3. Specifically, after obtaining the preform, Example 5 underwent sintering in an air atmosphere at a pressure of 101 kPa, a temperature of 1600°C, and a holding time of 2 hours, yielding an Al2O3 sintered block. This Al2O3 sintered block was then cut using a diamond wire saw to obtain an Al2O3 substrate blank, which was subsequently ground and polished to obtain the Al2O3 substrate. The properties of the sintered Al2O3 substrate after Example 5 are shown in Table 3.

[0079] Table 1. Sintering process and performance data of Al2O3 ceramic sintered blocks obtained in Examples 1-4

[0080] example Material Sintering method Temperature (°C) / Duration (h) Strength / MPa Density Hardness (HV) / GPa 1 <![CDATA[Al2O3]]> Atmospheric pressure sintering 900℃ / 1h 109.29±32.40 68.64％ 1.74±0.35 2 <![CDATA[Al2O3]]> Atmospheric pressure sintering 1000℃ / 1h 123.62±30.13 71.39％ 2.68±0.55 3 <![CDATA[Al2O3]]> Atmospheric pressure sintering 1100℃ / 1h 207.15±46.04 79.64％ 7.69±0.52 4 <![CDATA[Al2O3]]> Atmospheric pressure sintering 1300℃ / 0.5h 211.81±24.73 80.68％ 8.21±0.23

[0081] The Al2O3 sintered blocks of Examples 1 to 5 were processed by diamond wire saw in step (4) to obtain Al2O3 sheets. The diamond wire saw cutting parameters and results are shown in Table 2.

[0082] Table 2 Comparison of Multi-Wire Diamond Cutting Parameters and Results in Examples 1-5

[0083] Example Material Linear speed wire diameter feed rate Material removal rate 1 <![CDATA[Al2O3]]> 1.5m / s 0.42mm 3mm / min <![CDATA[109.50mm 2 / min]]> 2 <![CDATA[Al2O3]]> 1.5m / s 0.42mm 1.50 mm / min <![CDATA[54.75mm 2 / min]]> 3 <![CDATA[Al2O3]]> 1.5m / s 0.42mm 0.60 mm / min <![CDATA[21.90mm 2 / min]]> 4 <![CDATA[Al2O3]]> 1.5m / s 0.42mm 0.40 mm / min <![CDATA[14.60mm 2 / min]]> 5 <![CDATA[Al2O3]]> 1.5m / s 0.42mm 0.20mm / min <![CDATA[7.30mm 2 / min]]>

[0084] Table 1 shows that the Al2O3 sintered blocks obtained by sintering at lower temperatures and shorter times in this invention exhibit properties such as flexural strength of 100–300 MPa and Vickers hardness of 1.5–12 GPa. These low strength and low hardness properties are beneficial for diamond wire sawing, thereby improving processing efficiency. Table 2 shows that the Al2O3 sintered blocks obtained in Examples 1–4, sintered at lower temperatures and shorter times, achieve diamond wire sawing rates more than double those of Example 5.

[0085] In addition, in this embodiment of the invention, after diamond wire saw cutting, the Al2O3 sheet is subjected to high-temperature heat treatment in step (5). The performance data of the sample after high-temperature heat treatment is shown in Table 3. It can be clearly seen from the data in Table 3 that wire saw cutting does not affect the subsequent heat treatment. After high-temperature heat treatment, the performance of Al2O3 substrate is significantly improved compared with that of Al2O3 sintered block in terms of hardness, strength, density and thermal conductivity. The obtained Al2O3 substrate is highly dense or fully dense, and the product performance meets market demand.

[0086] Table 3 Heat treatment processes and properties of Examples 1-5

[0087]

[0088] The experimental results of Examples 1-5 demonstrate that the properties of the obtained Al2O3 sintered body can be controlled by adjusting the sintering process (sintering temperature and time), so that its flexural strength is between 100 and 300 MPa and its Vickers hardness is between 1.5 and 12 GPa. Under these properties, the efficiency of diamond wire sawing is higher.

[0089] Examples 6-9

[0090] This embodiment provides a method for preparing an easily processed, high-performance AlN substrate, including the following specific steps:

[0091] (1) Powder selection

[0092] AlN powder with an oxygen content of 0.87% and a particle size of D50 of 1.09 μm was used; Y2O3 with a purity of 99.9% and a particle size of D50 of 0.5 μm was used as the sintering aid, and the experiment was conducted according to the AlN:Y2O3 = 95:5 (mass ratio).

[0093] (2) Preparation of raw blank

[0094] Ball milling process: Weigh AlN powder and sintering aid and place them in a polytetrafluoroethylene (PTFE) ball milling jar. The ball milling solvent is anhydrous ethanol, and the ball milling media is high-purity ZrO2 grinding balls. The ratio of powder raw material: anhydrous ethanol: ZrO2 grinding balls is 1:2:2 (mass ratio). Then, fix the PTFE ball milling jar in a planetary ball mill and ball mill for 6 hours at a horizontal speed of 350 rpm and a vertical speed of 10 rpm. After that, pour the mixed slurry into a flask of a rotary evaporator and perform rotary evaporation at a temperature of 60°C. Finally, sieve the dried powder through a 100-mesh sieve.

[0095] Dry pressing process: A certain amount of ceramic powder is weighed and placed in a 64mm×64mm mold. A bidirectional pressing method is used, applying a pressure of 8MPa in both directions of the mold and holding the pressure for 60s. After demolding, a dry-pressed ceramic green body is obtained. Then, the dry-pressed ceramic green body is vacuum-sealed in a vacuum sealing bag and placed in a cold isostatic press with a pressure of 200MPa. The pressure increase rate is 40MPa / min, and the pressure is held for 5min to finally obtain a cold isostatic pressed ceramic green body for subsequent sintering.

[0096] (3) Sintering

[0097] Atmospheric pressure sintering was adopted, with N2 atmosphere. The temperature was first raised to 1300℃ at a rate of 10℃ / min, and then raised to the sintering temperature at a rate of 5℃ / min. The sintering process and properties of Examples 6 to 9 are shown in Table 4. After sintering, the temperature was lowered to 1300℃ at a rate of 5℃ / min, and then lowered to 800℃ at a rate of 10℃ / min. Finally, the temperature was cooled to room temperature with the furnace to obtain the sintered ceramic block.

[0098] (4) Diamond wire saw processing

[0099] The sintered ceramic block was machined using a diamond wire saw to obtain ceramic sheets with a thickness of 0.41 mm. The wire feed rate was 1.5 m / s, the wire diameter was 0.3 mm, and the feed rate was 0.25 mm / min. Water was used as the cutting fluid. After cutting, the sheets were cleaned using an ultrasonic cleaner with alcohol as the cleaning fluid. Subsequently, they were dried using a vacuum dryer at 60°C for 46 hours.

[0100] (5) High-temperature heat treatment

[0101] The ceramic sheet was subjected to high-temperature heat treatment in an N2 atmosphere with an atmosphere pressure of 101 kPa. The temperature was first raised to 1300°C at a rate of 10°C / min, and then raised to the heat treatment temperature at a rate of 5°C / min. The heat treatment process is shown in Table 5. Subsequently, the temperature was lowered to 1300°C at a rate of 5°C / min, and then lowered to 800°C at a rate of 10°C / min. Finally, the sheet was cooled to room temperature in the furnace to obtain a ceramic substrate blank. After grinding and polishing, the ceramic substrate was obtained.

[0102] Example 10

[0103] Example 10 served as the control group for Example 6, with identical formulation, powder, and preform preparation steps. The difference lay in the use of a conventional one-step sintering method, with sintering conditions identical to those in Example 6. The sintering process is shown in Table 6. Specifically, after obtaining the preform, Example 10 underwent sintering at a N2 atmosphere, a sintering pressure of 101 MPa, a sintering temperature of 1850°C, and a holding time of 4 hours to obtain an AlN sintered block. The AlN sintered block was then cut using a diamond wire saw to obtain an AlN substrate blank, which was subsequently ground and polished to obtain the AlN substrate. The properties of the AlN substrate after sintering in Example 10 are shown in Table 6.

[0104] Table 4. Sintering process and performance data of AlN ceramic sintered blocks obtained in Examples 6-9

[0105]

[0106]

[0107] The AlN sintered blocks in Examples 6-10 were processed by diamond wire saw to obtain AlN sheets. The diamond wire saw cutting parameters and results are shown in Table 5.

[0108] Table 5 Comparison of Multi-Wire Diamond Cutting Parameters and Results in Examples 6-10

[0109] Example Material Linear speed wire diameter feed rate Material removal rate 6 AlN 1.5m / s 0.42mm 3mm / min <![CDATA[78.00mm 2 / min]]> 7 AlN 1.5m / s 0.42mm 2mm / min <![CDATA[52.00mm 2 / min]]> 8 AlN 1.5m / s 0.42mm 0.7mm / min <![CDATA[18.20mm 2 / min]]> 9 AlN 1.5m / s 0.42mm 0.50 mm / min <![CDATA[13.00mm 2 / min]]> 10 AlN 1.5m / s 0.42mm 0.25mm / min <![CDATA[6.50mm 2 / min]]>

[0110] Table 4 shows that the AlN sintered blocks obtained by sintering at lower temperatures and shorter times exhibit properties such as flexural strength of 90–250 MPa and Vickers hardness of 1.5–10 GPa. These low strength and low hardness properties are beneficial for diamond wire sawing, thereby improving processing efficiency. Table 5 shows that in Examples 6–9, the diamond wire sawing rate of the AlN sintered blocks obtained by sintering at lower temperatures and shorter times was more than twice that of Example 10.

[0111] In addition, after diamond wire saw cutting, the AlN sheet is subjected to high-temperature heat treatment. The performance data of the sample after high-temperature heat treatment are shown in Table 6. It can be clearly seen from the data that wire saw cutting does not affect the subsequent heat treatment. After high-temperature heat treatment, the performance of AlN substrate is significantly improved compared with AlN sintered block in terms of hardness, strength, density and thermal conductivity. The obtained AlN substrate is highly dense or fully dense, and the product performance meets market demand.

[0112] Table 6. Process and performance data after heat treatment in Examples 6-9 and Example 10.

[0113]

[0114]

[0115] The experimental results of Examples 6-10 demonstrate that the properties of the obtained AlN sintered body can be controlled by adjusting the sintering process (sintering temperature and time), so that its flexural strength is between 90 and 250 MPa and its Vickers hardness is between 1.5 and 10 GPa. Under these properties, the efficiency of diamond wire sawing is higher.

[0116] Examples 11-19

[0117] This embodiment provides a method for preparing an easily processed, high-performance Si3N4 ceramic substrate, including the following specific steps:

[0118] (1) Powder selection

[0119] Si3N4 powder with a particle size of 0.8 μm and an oxygen content of 1.35% was used. The sintering aids were Y2O3 and MgO with a particle size of 0.5 μm and a purity of 99.9%, and the experiment was conducted according to the formula of Si3N4:MgO:Y2O3 = 95.23:1.47:3.30 (mass ratio).

[0120] (2) Preparation of raw blank

[0121] Ball milling process: Weigh Si3N4 powder and sintering aid and place them in a polytetrafluoroethylene (PTFE) ball mill jar. The ball milling solvent is anhydrous ethanol, and the ball milling media is high-purity Si3N4 grinding balls. The ratio of powder raw material: anhydrous ethanol: Si3N4 grinding balls is 1:2:2 (mass ratio). Then, fix the PTFE ball mill jar in a planetary ball mill and ball mill for 6 hours at a horizontal speed of 350 rpm and a vertical speed of 10 rpm. After that, pour the mixed slurry into a flask of a rotary evaporator and perform rotary evaporation at a temperature of 60°C. Finally, sieve the dried powder through a 100-mesh sieve.

[0122] Dry pressing process: A certain amount of Si3N4 powder is weighed and placed in a 64mm×64mm mold. A bidirectional pressing method is used, applying a pressure of 8MPa in both directions of the mold and holding the pressure for 60s. After demolding, a dry-pressed Si3N4 blank is obtained. Then, the dry-pressed Si3N4 blank is vacuum-sealed in a vacuum-sealed bag and placed in a cold isostatic press with a pressure of 200MPa. The pressure increase rate is 40MPa / min, and the pressure is held for 5min. Finally, a cold isostatic pressed Si3N4 blank is obtained for subsequent sintering.

[0123] (3) Sintering

[0124] The sintering was carried out under normal pressure in an atmosphere of N2. The temperature was first raised to 800°C at a rate of 10°C / min, and then raised to the sintering temperature at a rate of 5°C / min. The sintering temperature and holding time are shown in Table 7. The temperature was then lowered to 800°C at a rate of 5°C / min, and finally cooled to room temperature in the furnace to obtain Si3N4 sintered bulk material.

[0125] (4) Diamond wire saw processing

[0126] Si3N4 sintered blocks were machined using a diamond wire saw to obtain Si3N4 ceramic sheets with a thickness of 0.40 mm. The wire feed rate was 1.5 m / s, the wire diameter was 0.3 mm, and the feed rate was 0.2 mm / min. Water was used as the cutting fluid. After cutting, the sheets were cleaned using an ultrasonic cleaner with alcohol as the cleaning fluid. Subsequently, they were dried using a vacuum dryer at 60°C for 46 hours.

[0127] (5) High-temperature heat treatment

[0128] The Si3N4 ceramic sheet was subjected to high-temperature heat treatment in an N2 atmosphere with an atmosphere pressure of 2 MPa. The temperature was first raised to 800℃ at a rate of 10℃ / min, then raised to 1850℃ at a rate of 5℃ / min and held for 12 hours. The temperature was then lowered to 800℃ at a rate of 5℃ / min and finally cooled to room temperature in the furnace. After grinding and polishing, a Si3N4 ceramic substrate blank was obtained. After further grinding and polishing, the Si3N4 ceramic substrate was obtained.

[0129] Example 20

[0130] Example 20 served as the control group for Example 11, with identical formulation, powder, and green body preparation steps. The difference lay in the use of a conventional one-step sintering method, with sintering conditions identical to those of Example 11. The sintering process is shown in Table 7. Specifically, after obtaining the green body, Example 20 underwent sintering at a N2 atmosphere pressure of 2 MPa, a sintering temperature of 1850°C, and a holding time of 12 hours to obtain a Si3N4 sintered block. The Si3N4 sintered block was then cut using a diamond wire saw to obtain a Si3N4 ceramic substrate blank, which was subsequently ground and polished to obtain the Si3N4 ceramic substrate. The properties of the Si3N4 ceramic substrate after sintering are shown in Tables 7 and 9.

[0131] Examples 21-28

[0132] Examples 21 to 28 are extensions of Example 14. Their formulations, powders, green body preparation, sintering conditions, and wire saw cutting conditions are the same as those of Example 14. The difference lies in the use of different atmosphere pressures, different post-treatment temperatures, and different holding times in the post-treatment process. The performance data of Examples 21 to 28 are shown in Table 10.

[0133] Table 7. Sintering process and performance data of Si3N4 sintered bulk materials in Examples 11-20

[0134] example Temperature (°C) / Duration (h) Strength / MPa Density Hardness (HV) / GPa 11 1200℃ / 6h 65.68±13.81 59.20％ 0.91±0.07 12 1250℃ / 6h 73.30±11.90 60.33％ 1.63±0.11 13 1350℃ / 1h 101.32±12.47 71.58％ 1.54±0.28 14 1450℃ / 1h 155.53±16.38 71.93％ 1.59±0.26 15 1550℃ / 1h 340.25±14.73 73.00％ 3.66±0.31 16 1650℃ / 1h 553.65±29.93 78.30％ 4.43±0.34 17 1650℃ / 8h 664.16±34.77 84.60％ 10.83±0.61 18 1750℃ / 1h 599.42±28.64 81.11％ 8.18±0.46 19 1800℃ / 1h 654.31±28.42 84.56％ 12.84±0.52 20 1850℃ / 12h 816.65±27.56 99.20％ 17.21±0.89

[0135] The Si3N4 sintered blocks in Examples 11-20 were processed by diamond wire saw to obtain Si3N4 sheets. The diamond wire saw cutting parameters and results are shown in Table 8.

[0136] Table 8 Comparison of Multi-wire Diamond Wire Cutting Parameters and Results in Examples 11-20

[0137] Example Material Linear speed wire diameter feed rate Material removal rate 11 <![CDATA[Si3N4]]> 1.5m / s 0.42mm 3mm / min <![CDATA[75.00mm 2 / min]]> 12 <![CDATA[Si3N4]]> 1.5m / s 0.42mm 2mm / min <![CDATA[50.00mm 2 / min]]> 13 <![CDATA[Si3N4]]> 1.5m / s 0.42mm 1.2mm / min <![CDATA[29.83mm 2 / min]]> 14 <![CDATA[Si3N4]]> 1.5m / s 0.42mm 0.7mm / min <![CDATA[15.43mm 2 / min]]> 15 <![CDATA[Si3N4]]> 1.5m / s 0.42mm 0.25mm / min <![CDATA[5.38mm 2 / min <!-- 10 -->]]> 16 <![CDATA[Si3N4]]> 1.5m / s 0.42mm 0.05mm / min <![CDATA[1.00mm 2 / min]]> 17 <![CDATA[Si3N4]]> 1.5m / s 0.42mm 0.03mm / min <![CDATA[0.60mm 2 / min]]> 18 <![CDATA[Si3N4]]> 1.5m / s 0.42mm 0.04 mm / min <![CDATA[0.80mm 2 / min]]> 19 <![CDATA[Si3N4]]> 1.5m / s 0.42mm 0.03mm / min <![CDATA[0.60mm 2 / min]]> 20 <![CDATA[Si3N4]]> 1.5m / s 0.42mm 0.01mm / min <![CDATA[0.20mm 2 / min]]>

[0138] Table 7 shows that the Si3N4 sintered blocks obtained by sintering at lower temperatures and shorter times exhibit properties such as flexural strength of 90–600 MPa and Vickers hardness of 1.5–12 GPa. These low strength and low hardness properties are beneficial for diamond wire sawing, thereby improving processing efficiency. Table 8 shows that in Examples 13–16, the diamond wire sawing rate of the Si3N4 sintered blocks obtained at lower temperatures and shorter times was more than 5 times that of Example 20, significantly improving the wire sawing rate. In Examples 17–19, the diamond wire sawing rate was 3–4 times that of Example 20, demonstrating a certain degree of improvement.

[0139] In addition, after diamond wire saw cutting, the Si3N4 sheet is subjected to high-temperature heat treatment. The performance data of the sample after high-temperature heat treatment are shown in Table 9. Combining the data in Tables 9 and 10, it can be clearly seen that wire saw cutting does not affect the subsequent heat treatment. After high-temperature heat treatment, the performance of the Si3N4 substrate is significantly improved compared with that of the Si3N4 sintered block, such as hardness, strength, density and thermal conductivity. The obtained Si3N4 substrate is highly dense or fully dense, and the product performance meets market demand.

[0140] Table 9. Process and performance data after heat treatment in Examples 11-20

[0141] example Material Temperature / Duration Strength / MPa Density <![CDATA[Thermal conductivity / W·m -1 ·K -1 > Hardness (HV) / GPa 11 <![CDATA[Si3N4]]> 1850℃ / 12h 715.41±21.32 99.12％ 85.22±2.24 17.11±0.40 12 <![CDATA[Si3N4]]> 1850℃ / 12h 786.98±27.31 98.97％ 92.64±1.33 16.57±0.78 13 <![CDATA[Si3N4]]> 1850℃ / 12h 805.34±26.73 98.56％ 92.70±1.10 17.26±0.45 14 <![CDATA[Si3N4]]> 1850℃ / 12h 814.18±28.65 98.95％ 90.56±1.12 16.03±0.93 15 <![CDATA[Si3N4]]> 1850℃ / 12h 820.16±27.23 99.09％ 89.38±2.31 17.28±0.75 16 <![CDATA[Si3N4]]> 1850℃ / 12h 825.00±25.62 99.08％ 87.49±2.65 15.39±0.82 17 <![CDATA[Si3N4]]> 1850℃ / 12h 837.09±24.24 99.21％ 88.95±2.67 16.07±0.64 18 <![CDATA[Si3N4]]> 1850℃ / 12h 835.50±25.29 99.27％ 91.72±2.30 17.70±0.33 19 <![CDATA[Si3N4]]> 1850℃ / 12h 821.40±30.43 99.27％ 90.65±1.14 16.33±0.84 20 <![CDATA[Si3N4]]> 1850℃ / 12h 816.65±27.56 99.20％ 85.24±1.66 17.21±0.89

[0142] The experimental results of Examples 11-19 demonstrate that the properties of the obtained Si3N4 sintered body can be controlled by adjusting the sintering method, sintering time, sintering temperature, sintering atmosphere, and sintering pressure, achieving a flexural strength of 90-600 MPa and a Vickers hardness of 1.5-12 GPa. In Examples 11-12, due to excessively low sintering temperatures, the resulting sintered blocks had extremely low strength and poor mechanical properties, failing to meet processing requirements. Sample breakage occurred during diamond wire sawing. Even with rapid diamond wire sawing, the resulting Si3N4 ceramic sheets exhibited significant warping after subsequent high-temperature heat treatment due to excessive density changes. In Example 17, compared to Example 16, the sintering time was longer, resulting in significantly improved density and mechanical properties of the sintered body, but the wire sawing rate was lower than in Example 16. In Examples 18-19, due to excessively high sintering temperatures, the sintered blocks had better density and mechanical properties, but the wire sawing rate was lower than in Example 16. From the perspective of increasing the processing speed of wire saws, the sintering process in Examples 13-15 is optimal.

[0143] In summary, the optimal sintering process for Si3N4 sintered bulk materials is 1350–1550℃ with a holding time of 1 hour. This process significantly improves the density and mechanical properties of the materials, allowing for diamond wire sawing while simultaneously increasing processing speed and reducing processing difficulty. This sintering process is the optimal method for obtaining easily machinable, high-performance Si3N4 substrates.

[0144] Table 10. High-temperature heat treatment process parameters and properties of the obtained Si3N4 substrates in Examples 21-28

[0145] example Temperature / Duration (h) Atmospheric pressure Strength / MPa Density <![CDATA[Thermal conductivity / W·m -1 ·K -1 > Hardness (HV) / GPa 21 1850℃ / 12h 2MPa 715.41±21.32 99.12％ 85.22±2.24 17.11±0.40 22 1900℃ / 12h 2MPa 706.51±28.17 98.97％ 94.54±1.97 15.24±0.61 23 1850℃ / 6h 101 kPa 505.11±24.95 97.56％ 61.56±1.73 16.28±0.64 24 1800℃ / 6h 101 kPa 664.58±26.25 98.95％ 60.39±1.37 17.75±0.57 25 1850℃ / 12h 101kPa 650.80±26.16 99.09％ 88.62±2.37 16.19±0.59 26 1850℃ / 12h 2MPa 725.60±25.77 99.08％ 85.92±2.62 17.98±0.62 27 1850℃ / 12h 2MPa 537.69±21.08 98.21％ 89.44±2.71 14.07±0.43 28 1850℃ / 12h 2MPa 735.45±25.13 99.27％ 91.76±2.94 17.52±0.63

[0146] The results in Table 10 show that during the heat treatment process, the increase in atmosphere pressure inhibits the decomposition of Si3N4, thereby enabling the ceramic sheet to achieve a higher density. Changes in sintering atmosphere pressure lead to microscopic changes in Si3N4 material during sintering, which in turn affects sintering performance. Therefore, under the premise that the heat treatment process is preferably 1800-1900℃ and the holding time is greater than 6 hours, the preferred sintering atmosphere pressure is 2MPa.

[0147] Furthermore, Raman spectroscopy analysis was performed on the Si3N4 ceramic substrates prepared in Examples 20 and 13-16, and the results are as follows: Figure 1 As shown. In Example 20, the Si3N4 ceramic substrate had a region located at 520±2 cm⁻¹. -1 The peak is amorphous Si, while the Si3N4 ceramic substrates prepared in Examples 13-16 do not have this characteristic peak, indicating that the Si3N4 ceramic substrate prepared using the preparation method of the present invention can eliminate amorphous Si. Since amorphous Si has low thermal conductivity, its presence inside Si3N4 will reduce the heat transfer efficiency. Therefore, the elimination of amorphous Si is beneficial to the thermal conductivity of the Si3N4 substrate to a certain extent.

[0148] Further comparison of the Raman peak values ​​of Example 14 and Example 20, such as Figure 2 As shown, the Si3N4 substrate prepared according to the method of the present invention is characterized by a Raman spectral peak shifted to the left by 2 ± 0.5 cm⁻¹. -1 Located at 520±2cm -1 The Si peak disappeared.

[0149] Therefore, this invention achieves Si3N4 ceramic sintered blocks with properties such as flexural strength of 90–600 MPa (preferably 100–500 MPa) and Vickers hardness of 1.5–12 GPa (preferably 1.5–8 GPa) through sintering at lower temperatures and shorter times. These low strength and low hardness properties facilitate diamond wire saw cutting, thereby improving processing efficiency. The processing speed is more than twice that of traditional methods.

[0150] Furthermore, after diamond wire saw cutting, this invention performs high-temperature heat treatment on the ceramic sheets according to the characteristics of different types of ceramic powders. After high-temperature heat treatment, the performance of the ceramic substrate is significantly improved compared to that of the sintered ceramic block, including hardness, strength, density, and thermal conductivity. The resulting ceramic substrate is highly dense or fully dense, and its performance meets market demands. In contrast, ceramic substrates prepared using traditional methods are prone to defects, such as… Figure 3As shown, under traditional preparation methods, the large ceramic blocks obtained in Examples 5, 10, and 20 suffer from uneven heating due to varying thermal radiation distances at different locations, resulting in inconsistent shrinkage at different locations. This leads to uneven color, uneven density, and porosity in the sliced ​​ceramics. The preparation method of this invention effectively solves this problem. The sintered ceramic sheets experience more uniform heating during sintering, and the ceramic substrate exhibits superior thermal conductivity and mechanical properties, such as… Figure 4 As shown, the three ceramic materials prepared in Examples 3, 8, and 14 all exhibit good uniformity.

[0151] The above embodiments only list Al2O3, AlN, and Si3N4 as special cases, aiming to illustrate that the present invention can effectively control the sintering performance of materials by adjusting one or more of the sintering methods, sintering time, sintering temperature, sintering atmosphere, and sintering pressure (preferably adjusting sintering temperature and sintering time), so as to facilitate diamond wire saw processing; at the same time, it meets the requirements of further improving the density, hardness, flexural strength, and thermal conductivity of ceramic sheets under high-temperature heat treatment, ultimately meeting the finished product performance requirements of ceramic substrates.

[0152] In summary, the ceramic substrates prepared by the method of this invention have comparable performance to those prepared by conventional one-time sintering methods. The preparation method of this invention combines sintering performance control with high-temperature heat treatment, which does not reduce the performance of the ceramic substrates. Moreover, the ceramic sintered body obtained by sintering performance control has lower hardness and meets certain bending strength requirements, making it easier to process with diamond wire saws, significantly improving the processing speed and reducing the processing difficulty.

[0153] It should be noted that the processing speed of a diamond wire saw is related to the mechanical properties of the material being processed. Undoubtedly, the sintered ceramic body with lower hardness obtained by the present invention through sintering performance control is easier to cut with a diamond wire saw. Furthermore, the hardness and bending strength of the sintered ceramic body can be controlled by adjusting the sintering temperature and sintering time, thereby increasing the processing speed of the diamond wire saw and reducing the processing difficulty. After subsequent high-temperature heat treatment, the ceramic powder and sintering aids are liquefied at high temperature to improve the strength, density and other properties of the ceramic sheet, ultimately resulting in a high-performance ceramic substrate.

[0154] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0155] The above description describes specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing an easily processed high-performance ceramic substrate, characterized in that, Includes the following steps: S1. The ceramic powder is shaped and processed to obtain a ceramic blank; S2. The ceramic blank is sintered to obtain a sintered ceramic block. The density of the sintered ceramic block is 50-95%, the bending strength is 20-85% of the bending strength of the finished product, and the Vickers hardness is 1.5-12 GPa. S3. The sintered ceramic block is wire-sawed to obtain ceramic sheets with a length of 50-200mm, a width of 40-200mm, and a thickness of 0.35-2mm. S4. The ceramic sheet is subjected to high-temperature heat treatment to repair the surface defects generated during the wire sawing process, and then ground and polished to obtain a high-performance ceramic substrate. The ceramic powder is any one of Al2O3, AlN, Si3N4, and SiC; The temperature of the high-temperature heat treatment in step S4 is higher than the sintering temperature in step S2. The high-temperature heat treatment time in step S4 is longer than the sintering time in step S2. When the ceramic powder is Al2O3, the sintering process in step S2 is as follows: sintering temperature is 900~1500℃, and holding time is 0.5~6 hours; the high-temperature heat treatment process in step S4 is as follows: in an atmosphere of Ar, N2 or air, the pressure is 10... -5 The heat treatment is carried out under conditions of Pa~300MPa, the heat treatment temperature is 1400~1700℃, and the holding time is 1~24 hours; When the ceramic powder is AlN, the sintering process in step S2 is as follows: sintering temperature is 1300~1750℃, and holding time is 0.5~6 hours; the high-temperature heat treatment process in step S4 is as follows: in an Ar or N2 atmosphere, the pressure is 10... -5 The heat treatment is carried out under conditions of Pa~300MPa, the heat treatment temperature is 1600~1900℃, and the holding time is 1~24 hours. When the ceramic powder is Si3N4, the sintering process in step S2 is as follows: sintering temperature is 1300~1750℃, and holding time is 0.5~6 hours; the high-temperature heat treatment process in step S4 is as follows: in an Ar or N2 atmosphere, the pressure is 10... -5 The heat treatment is carried out under conditions of Pa~300MPa, the heat treatment temperature is 1700~2000℃, and the holding time is 1~24 hours; When the ceramic powder is SiC, the sintering process in step S2 is as follows: sintering temperature is 1500~1800℃, and holding time is 0.5~6 hours; the high-temperature heat treatment process in step S4 is as follows: in an Ar or N2 atmosphere, the pressure is 10... -5 The heat treatment is carried out under conditions of Pa~300MPa, with a heat treatment temperature of 1800~2200℃ and a holding time of 1~24 hours.

2. The method for preparing an easily processed high-performance ceramic substrate as described in claim 1, characterized in that, Between steps S3 and S4, the process also includes cleaning and drying the processed ceramic sheets.

3. The method for preparing an easily processed high-performance ceramic substrate as described in claim 1, characterized in that, The wire sawing process refers to diamond wire sawing or a composite processing method based on diamond wire sawing.

4. The method for preparing an easily processed high-performance ceramic substrate as described in claim 1, characterized in that, Step S1 further includes mixing the sintering aid with the ceramic powder, dry pressing, and cold isostatic pressing to obtain the ceramic blank.

5. The method for preparing an easily processed high-performance ceramic substrate as described in claim 4, characterized in that, The pressure for dry pressing is 1~50MPa, and the holding time is 10~120s. The pressure for cold isostatic pressing is 50~300MPa, and the holding time is 120~300s.

6. The ceramic substrate prepared by the method for preparing an easily machinable high-performance ceramic substrate according to any one of claims 1 to 5, characterized in that, The ceramic substrate has a uniform color, no cut marks, no cracks, and no regional defects.

7. A ceramic substrate according to claim 6, characterized in that, When the ceramic powder is Si3N4, a Si3N4 ceramic substrate is prepared, and the Raman spectrum peak of the Si3N4 ceramic substrate is shifted to the left by 2 ± 0.5 cm. -1 Located at 520±2cm -1 The Si peak disappeared.

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