Grading proportion formula for high-conductivity glass-bonded hot silicon carbide ceramic radiating fin

Abstract

The invention provides a grading proportion formula for a high-conductivity glass-bonded hot silicon carbide ceramic cooling fin. The grading proportion formula comprises the following raw materials in percentage by mass: 75-85% of three-grade grading silicon carbide powder, 5-8% of glass powder, 0.5-2% of boron nitride powder, 5% of a BP-72 binder and 5-12% of PVA. The three-level grading silicon carbide powder is composed of 100-mesh silicon carbide powder, 600-mesh silicon carbide powder and 1500-mesh silicon carbide powder, and the mass ratio of the three silicon carbide powder is 63: 27: 10. According to the grading proportion formula for the high-conductivity glass-bonded hot silicon carbide ceramic cooling fin, provided by the invention, raw materials including 75 to 85 percent of three-grade grading silicon carbide powder, 5 to 8 percent of glass powder, 0.5 to 2 percent of boron nitride powder, 5 percent of BP-72 binder and 5 to 12 percent of PVA (Polyvinyl Alcohol) are matched and matched with a preparation process of mixing, granulating, dry-pressing and molding, and degumming and sintering; the three-stage grading silicon carbide powder can realize the close packing of particles, reduce the porosity, and do not need to additionally add a densifying auxiliary agent.

Description

Technical Field

[0001] This invention relates to the field of ceramic heat dissipation materials technology, and in particular to a gradation ratio formulation for high-conductivity glass-bonded thermal silicon carbide ceramic heat sinks. Background Technology

[0002] With the rapid development of electronic technology towards high power, miniaturization, and integration, heat dissipation has become a core bottleneck restricting the performance improvement and lifespan extension of electronic devices. Currently, the mainstream heat sink materials on the market are mainly divided into four categories: metal heat sinks, ceramic heat sinks, graphite heat sinks, and carbon fiber composite heat sinks.

[0003] Metal heat sinks (such as those made of copper and aluminum) have become the most widely used heat dissipation materials due to their high thermal conductivity (Cu and Al heat sinks can reach over 200 W / (m·K)). However, as a conductive medium, metal materials can cause electromagnetic interference due to their parasitic capacitance and inductance effects, and their coefficient of thermal expansion differs significantly from that of silicon chips, which can easily lead to device packaging failure. Graphite heat sinks are flexible and lightweight, making them suitable for heat dissipation in ultra-thin devices, but their low thermal conductivity in the vertical direction requires the use of other heat dissipation materials, limiting their applicability. Carbon fiber composite heat sinks are suitable for scenarios with special requirements for weight and strength (such as drones and new energy vehicles), but they are expensive and their thermal conductivity is slightly inferior to that of metals. Traditional silicon carbide ceramic heat sinks have the advantages of good insulation, high temperature resistance, and corrosion resistance, making them suitable for heat dissipation of high-frequency electronic components or high-temperature environments. However, they have drawbacks such as high brittleness, high densification costs, and high processing difficulty. Furthermore, the thermal conductivity of heat sinks made from single-size silicon carbide powder is usually less than 8 W / (m·K), which is difficult to meet the heat dissipation requirements of high-power devices.

[0004] Therefore, it is necessary to provide a gradation ratio formulation for high-conductivity glass-bonded thermal silicon carbide ceramic heat sinks to solve the above-mentioned technical problems. Summary of the Invention

[0005] This invention provides a gradation ratio formula for high-conductivity glass-bonded thermal silicon carbide ceramic heat sinks, which solves the problems of low thermal conductivity, high densification cost, poor molding quality, and poor compatibility between single-particle-size raw materials and spray granulation process in traditional silicon carbide ceramic heat sinks.

[0006] To solve the above-mentioned technical problems, the present invention provides a gradation ratio formula for a high-conductivity glass bonding thermal silicon carbide ceramic heat sink, comprising the following raw materials by mass fraction: The three-graded silicon carbide powder consists of 75-85% silicon carbide powder, 5-8% glass powder, 0.5-2% boron nitride powder, 5% BP-72 binder, and 5-12% PVA. The three-graded silicon carbide powder is composed of 100-mesh, 600-mesh, and 1500-mesh silicon carbide powders in a mass ratio of 63:27:10.

[0007] Preferably, the silicon carbide powder has a purity of ≥98% and the particle morphology is irregular.

[0008] Preferably, the glass powder has a D50 of 5-9 μm, a softening temperature of 800℃, and a melting temperature of 860-990℃.

[0009] Preferably, the boron nitride powder is hexagonal in phase, with a purity ≥98.5% and D50=0.5μm.

[0010] Preferably, the degree of polymerization of the PVA is 1700-1800 and the degree of hydrolysis is 86-89%.

[0011] Preferably, the BP-72 adhesive is composed of polyacrylic acid alkanolamine salt and water in a mass ratio of 7:3.

[0012] Preferably, the preparation method of the gradation ratio formula for the high-conductivity glass-bonded thermal silicon carbide ceramic heat sink includes the following steps: S1. Mixing: Thoroughly mix the dried raw materials of silicon carbide powder, glass powder, and boron nitride powder for 10 minutes, then add BP-72 and PVA and continue stirring for 10 minutes. Place the mixed raw materials in a 110℃ hot air circulating oven and dry for 5 hours, controlling the moisture content to ≤0.8%. Then crush them in a 32000r / min pulverizer. S2. Mixed granulation: Granulation is carried out using a mixed granulator to obtain particles with a diameter of 200-500μm; S3. Dry pressing: Using a 200T hydraulic tablet press, the tablets are pressed once at 140-200MPa and then held under pressure for 5 seconds to obtain a density ≥2.4g / cm³. 3 raw blanks; S4. Debinding and sintering: In a high-temperature continuous pusher furnace, the temperature is raised to 700℃ in 100 minutes to complete the debinding, then the temperature is rapidly raised to 850℃ and held for 120 minutes. The furnace is then cooled to room temperature to obtain the finished product.

[0013] Preferably, in step S1, the crushing time of the pulverizer is 1 minute, and the pulverizer passes through an 80-mesh sieve after 1 minute of crushing.

[0014] Preferably, in step S3, the mold material is cemented carbide and the size is 80×80mm.

[0015] Preferably, in step S4, the purpose of removing the adhesive is to completely decompose and remove the organic adhesive, so as to avoid the carbonization of the organic adhesive during sintering and affect the surface state of the sample. The sintering atmosphere is air.

[0016] Compared with related technologies, the gradation ratio formula for high-conductivity glass-bonded thermal silicon carbide ceramic heat sinks provided by the present invention has the following beneficial effects: This invention provides a graded formulation for high-conductivity glass-bonded silicon carbide ceramic heat sinks. The formulation comprises 75-85% tri-graded silicon carbide powder, 5-8% glass powder, 0.5-2% boron nitride powder, 5% BP-72 binder, and 5-12% PVA. Combined with a preparation process of mixing, granulation, dry pressing, and debinding sintering, the tri-graded silicon carbide powder achieves close particle packing, reducing porosity and eliminating the need for additional densifying agents. During sintering, the glass powder melts to form a binder phase, firmly bonding the silicon carbide particles with the boron nitride powder, improving structural integrity, and achieving high density without high-temperature, high-pressure sintering. The boron nitride powder optimizes the heat conduction path, and PVA and BP-72 synergistically enhance molding stability, preventing green body cracking. This solves the problems of low thermal conductivity, high densification costs, and poor molding quality associated with traditional formulations. The finished product achieves a thermal conductivity of over 12 W / (m·K) and a density ≥2.4 g / cm³. 3 It combines good insulation and mechanical strength, making it suitable for the heat dissipation needs of high-power electronic devices. Attached Figure Description

[0017] Figure 1 The present invention provides a flowchart of a method for preparing a gradation ratio formulation for a high-conductivity glass-bonded thermal silicon carbide ceramic heat sink. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0019] Please refer to the following: Figure 1 , Figure 1 The present invention provides a flowchart of a method for preparing a gradation ratio formulation for a high-conductivity glass-bonded thermal silicon carbide ceramic heat sink.

[0020] A gradation formula for high-conductivity glass-bonded thermal silicon carbide ceramic heat sinks comprises the following raw materials by mass fraction: The three-graded silicon carbide powder consists of 75-85% silicon carbide powder, 5-8% glass powder, 0.5-2% boron nitride powder, 5% BP-72 binder, and 5-12% PVA. The three-graded silicon carbide powder is composed of 100-mesh, 600-mesh, and 1500-mesh silicon carbide powders in a mass ratio of 63:27:10.

[0021] The silicon carbide powder has a purity of ≥98% and the particle morphology is irregular.

[0022] The glass powder has a D50 of 5-9 μm, a softening temperature of 800℃, and a melting temperature of 860-990℃.

[0023] The boron nitride powder is hexagonal in phase, with a purity ≥98.5% and D50=0.5μm.

[0024] The degree of polymerization of the PVA is 1700-1800, and the degree of hydrolysis is 86-89%.

[0025] The BP-72 adhesive is composed of polyacrylic acid alkanolamine salt and water in a mass ratio of 7:3.

[0026] The specific specifications of each raw material are shown in Table 1 below: Table 1 Experimental materials and their properties raw material Specification Proportion Element characteristic silicon carbide GC100 63 Purity > 98% The particles have an irregular shape. GC600 27 GC1500 10 adhesive BP-72 5% Polyacrylic alkanolamine salt:water = 7:3 / PVA PB-17 10% / Degree of polymerization = 1700-1800; Degree of alcoholysis = 86-89% glass powder D50 = 5-9μm 8% / The softening temperature is 800°C, and the melting temperature is 860-990°C. Boron nitride D50=0.5μm 1% Purity ≥ 98.5% Hexagonal crystal phase The preparation method of the gradation ratio formula for high-conductivity glass-bonded thermal silicon carbide ceramic heat sink includes the following steps: S1. Mixing: Thoroughly mix the dried raw materials of silicon carbide powder, glass powder, and boron nitride powder for 10 minutes, then add BP-72 and PVA and continue stirring for 10 minutes. Place the mixed raw materials in a 110℃ hot air circulating oven and dry for 5 hours, controlling the moisture content to ≤0.8%. Then crush them in a 32000r / min pulverizer. S2. Mixed granulation: Granulation is carried out using a mixed granulator to obtain particles with a diameter of 200-500μm; S3. Dry pressing: Using a 200T hydraulic tablet press, the tablets are pressed once at 140-200MPa and then held under pressure for 5 seconds to obtain a density ≥2.4g / cm³. 3 raw blanks; S4. Debinding and sintering: In a high-temperature continuous pusher furnace, the temperature is raised to 700℃ in 100 minutes to complete the debinding, then the temperature is rapidly raised to 850℃ and held for 120 minutes. The furnace is then cooled to room temperature to obtain the finished product.

[0027] In step S1, the crushing time of the pulverizer is 1 minute, and the pulverizer passes through an 80-mesh sieve after 1 minute of crushing.

[0028] In step S3, the mold is made of cemented carbide and has a size of 80×80mm.

[0029] In step S4, the purpose of removing the adhesive is to completely decompose and remove the organic adhesive, and to avoid the carbonization of the organic adhesive during sintering, which would affect the surface condition of the sample. The sintering atmosphere is air.

[0030] Raw material gradation optimization experiment To verify the optimal ratio of three-stage graded silicon carbide powder, multiple comparative experiments with different gradation schemes were designed to test the key properties of the green body and sintered products. The results are shown in Table 2 below: Silicon carbide gradation ratio (100 mesh: 600 mesh: 1500 mesh) glass powder content (%) BP-72 binder content (%) PVA content (%) Boron nitride content (%) Green density (g / cm) 3 ) Porosity after sintering (%) Density after sintering (g / cm) 3 ) Thermal conductivity (W / (m・K) 50:30:208510 / 2.44120.282.2914.4160:20:208510 / 2.41720.662.2413.2163:27:108510 / 2.49120.992.2715.463:27:1085101 / / / 22.03-23.5663:27:105510 / / 21.952.37622.363:27:105810 / / 22.12.37420.863:27:1051010 / / / / 20.763:27:1058101 / / / 22.3-24.463:27:1085101 / / / 22.2-22.667:23:1085101 / / / 23.47 Experimental results show that when the silicon carbide gradation ratio is 100 mesh:600 mesh:1500 mesh = 63:27:10, both the green density and the thermal conductivity after sintering reach optimal levels. Furthermore, the addition of 1% boron nitride powder significantly improves the thermal conductivity compared to the boron nitride-free formulation, reaching a maximum of 24.4 W / (m·K). Meanwhile, the tap density test results for different gradation schemes are shown in Table 3 below, further verifying the superiority of the 63:27:10 gradation ratio. Serial Number Silicon carbide gradation (mesh size and mass fraction) <![CDATA[Tap density (g / cm 3 ).]]> 1 100 mesh (100%) 1.67 2 600 mesh (100%) 1.72 3 1500 mesh (100%) 1.67 4 100 mesh (70%) + 3000 mesh (30%) 2.00 5 100 mesh (60%) + 600 mesh (40%) 2.08 6 100 mesh (63%) + 600 mesh (27%) + 1500 mesh (10%) 2.17 7 100 mesh (63%) + 600 mesh (27%) + 3000 mesh (10%) 2.13 Comparison of granulation methods The effects of mixed granulation and spray granulation processes on product performance were compared, and the test results are shown in Table 4 below: Granulation method Silicon carbide gradation ratio Porosity (%) <![CDATA[Density (g / cm 3 ).]]> Thermal conductivity (W / (m・K)) Powder properties Spray granulation 100 mesh: 3000 mesh = 75:20 21.55 2.2 18.01 Moisture content 0.8%, bulk density 0.75-0.8 g / ml, flowability 107-139 s / 50g Spray granulation 100 mesh: 600 mesh: 1500 mesh = 63:27:10 (1 / 3 amount) 29.79 2.042 9.5 Moisture content 0.8%, bulk density 1.02 g / ml, coarse sand and fine powder separated. Mixed granulation 100 mesh: 600 mesh: 1500 mesh = 63:27:10 (1 / 3 amount) 27.29 2.124 15.9 Moisture content 0.5%, bulk density 1.15-1.17 g / ml, high mixing uniformity. Mixed granulation 100 mesh: 600 mesh: 1500 mesh = 63:27:10 + 5% glass powder + 5% BP-72 21.95 2.376 22.3 Moisture content ≤0.8%, particle size 200-500μm, good molding stability. Experimental conclusion: The samples prepared by the mixed granulation process have more stable and higher overall thermal conductivity, which can basically reach more than 20 W / (m・K). In contrast, spray granulation has problems such as unstable thermal conductivity and particle separation. Therefore, the mixed granulation process is selected in this invention.

[0031] Experiment on the effect of glass powder content on mechanical properties The flexural strength of samples with different glass powder contents was tested, and the results are shown in Table 5 below: Glass powder content (%) Average bending strength (MPa) 5 27.35 6 27.98 7 33.23 8 37.43 9 37.95 10 41.97 The results showed that when the glass powder content was in the range of 5-8%, the bending strength of the sample increased significantly with the increase of the content. Combined with the thermal conductivity test, the optimal glass powder content range was determined to be 5-8%, at which point the sample had both good mechanical properties and thermal conductivity.

[0032] Experiment on the effect of boron nitride on product strength The bending strength of products with and without boron nitride formulations was tested using a universal testing machine. The results are shown in Table 6 below. Formula type serial number Maximum force (kg) Bending strength Rbb (kg / mm) 2 ) Elastic modulus Eb (kg / mm) 2 ) Boron nitride-free ---- 117.9038 0.677 0.024218.7117 0.642 0.022316.6638 0.629 0.023413.1249 0.509 0.023514.3828 0.533 0.024619.3639 0.655 0.021713.8701 0.523 0.024818.7041 0.633 0.022 Average 14.7472 0.534 0.020 CV (%) 12.8 12.3 11.9 Boron nitride-containing (1%) ---- 114.204 90.51 90.023 215.95 740.55 90.021 316.20 190.56 40.021 418.22 250.63 60.022 519.86 630.66 80.021 614.59 600.50 00.021 718.81 890.65 10.024 815.61 720.55 70.025 916.61 190.61 20.025 1016.60 750.55 30.021 Average 16.67 040.58 20.022 CV (%) 3.3 2.9 2.5 Note: Although the average flexural strength of the boron nitride-containing formulation is slightly higher than that of the boron nitride-free formulation, this result needs to be verified with more samples due to the non-uniformity of the sample size. The effect of boron nitride on improving molding quality and thermal conductivity has been clearly demonstrated through experiments.

[0033] The performance comparison between the product of this invention and conventional heat sink products is shown in Table 7 below: Product Type Weight range (g) Porosity (%) <![CDATA[Apparent density (g / cm 3 ).]]> Thermal conductivity (W / (m・K)) Core advantages The product of this invention (K25) 8.0-8.6 22.3 2.35 21-30 Insulation eliminates electromagnetic interference, has a low coefficient of thermal expansion, and is compatible with chip heat dissipation. Conventional single-particle-size silicon carbide products (K9) 5.9-6.1 40.5 1.7 5.7-8 Low cost, but poor thermal conductivity. Metal heat sink (Cu / Al) / / 8.9 / 2.7 200 and above It has high thermal conductivity, but suffers from electromagnetic interference and a mismatch in thermal expansion coefficients. Meanwhile, long-term stability tests were conducted on the product of this invention. After being placed in an environment of 80℃ and 80%RH for 144 hours, the thermal conductivity remained at approximately 22.12 W / (m·K), indicating good stability. The test data are shown in Table 8 below: Test Date Time-of-Effect Category K9 product average thermal conductivity (W / (m・K) The average thermal conductivity (W / ) of the product of this invention (K25) (m・K) 10.22 First time 7.46 22.55 10.25 72 H 7.48 22.41 10.28 144 H 7.52 22.12 Compared with related technologies, the gradation ratio formula for high-conductivity glass-bonded thermal silicon carbide ceramic heat sinks provided by the present invention has the following beneficial effects: By using a raw material ratio of 75-85% three-graded silicon carbide powder, 5-8% glass powder, 0.5-2% boron nitride powder, 5% BP-72 binder, and 5-12% PVA, and employing a preparation process of mixing, granulation, dry pressing, and debinding sintering, silicon carbide ceramic heat sinks can be manufactured. The three-graded silicon carbide powder achieves close particle packing, reducing porosity and eliminating the need for additional densification agents. During sintering, the glass powder melts to form a binder phase, firmly bonding the silicon carbide particles with the boron nitride powder, improving structural integrity, and achieving high density without high-temperature, high-pressure sintering. The boron nitride powder optimizes the heat conduction path, and PVA and BP-72 synergistically enhance molding stability, preventing green body cracking. This solves the problems of low thermal conductivity, high densification costs, and poor molding quality associated with traditional formulations. The finished product achieves a thermal conductivity of over 12 W / (m·K) and a density ≥2.4 g / cm³. 3 It combines good insulation and mechanical strength, making it suitable for the heat dissipation needs of high-power electronic devices.

[0034] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A gradation formula for bonding high-conductivity glass to thermally bonded silicon carbide ceramic heat sinks, characterized in that, Raw materials including the following mass fractions: The three-graded silicon carbide powder consists of 75-85% silicon carbide powder, 5-8% glass powder, 0.5-2% boron nitride powder, 5% BP-72 binder, and 5-12% PVA. The three-graded silicon carbide powder is composed of 100-mesh, 600-mesh, and 1500-mesh silicon carbide powders in a mass ratio of 63:27:

10.

2. The gradation formula for a high-conductivity glass-bonded thermal silicon carbide ceramic heat sink according to claim 1, characterized in that, The silicon carbide powder has a purity of ≥98% and the particle morphology is irregular.

3. The gradation formula for a high-conductivity glass-bonded thermal silicon carbide ceramic heat sink according to claim 1, characterized in that, The glass powder has a D50 of 5-9 μm, a softening temperature of 800℃, and a melting temperature of 860-990℃.

4. The gradation formula for a high-conductivity glass-bonded thermal silicon carbide ceramic heat sink according to claim 1, characterized in that, The boron nitride powder is hexagonal in phase, with a purity ≥98.5% and D50=0.5μm.

5. The gradation formula for a high-conductivity glass-bonded thermal silicon carbide ceramic heat sink according to claim 1, characterized in that, The degree of polymerization of the PVA is 1700-1800, and the degree of hydrolysis is 86-89%.

6. The gradation formula for a high-conductivity glass-bonded thermal silicon carbide ceramic heat sink according to claim 1, characterized in that, The BP-72 adhesive is composed of polyacrylic acid alkanolamine salt and water in a mass ratio of 7:

3.

7. The gradation formula for a high-conductivity glass-bonded thermal silicon carbide ceramic heat sink according to claim 1, characterized in that, The preparation method of the gradation ratio formula for high-conductivity glass-bonded thermal silicon carbide ceramic heat sink includes the following steps: S1. Mixing: Thoroughly mix the dried raw materials of silicon carbide powder, glass powder, and boron nitride powder for 10 minutes, then add BP-72 and PVA and continue stirring for 10 minutes. Place the mixed raw materials in a 110℃ hot air circulating oven and dry for 5 hours, controlling the moisture content to ≤0.8%. Then crush them in a 32000r / min pulverizer. S2. Mixed granulation: Granulation is carried out using a mixed granulator to obtain particles with a diameter of 200-500μm; S3. Dry pressing: Using a 200T hydraulic tablet press, the tablets are pressed once at 140-200MPa and then held under pressure for 5 seconds to obtain a density ≥2.4g / cm³. 3 raw blanks; S4. Debinding and sintering: In a high-temperature continuous pusher furnace, the temperature is raised to 700℃ in 100 minutes to complete the debinding, then the temperature is rapidly raised to 850℃ and held for 120 minutes. The furnace is then cooled to room temperature to obtain the finished product.

8. The gradation ratio formulation for a high-conductivity glass-bonded thermal silicon carbide ceramic heat sink according to claim 7, characterized in that, In step S1, the crushing time of the pulverizer is 1 minute, and the pulverizer passes through an 80-mesh sieve after 1 minute of crushing.

9. The gradation formula for a high-conductivity glass-bonded thermal silicon carbide ceramic heat sink according to claim 7, characterized in that, In step S3, the mold is made of cemented carbide and has a size of 80×80mm.

10. The gradation formula for a high-conductivity glass-bonded thermal silicon carbide ceramic heat sink according to claim 7, characterized in that, In step S4, the purpose of removing the adhesive is to completely decompose and remove the organic adhesive, so as to avoid the carbonization of the organic adhesive during the sintering process from affecting the surface state of the sample. The sintering atmosphere is air.

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