High thermal conductive silicon / aluminum composite material, preparation method and application thereof

Abstract

The application discloses a high-thermal-conductivity silicon / aluminum composite material and a preparation method and application thereof, and belongs to the technical field of silicon / aluminum composite materials. The preparation method comprises the following steps: mixing silicon powder and aluminum powder by ball milling to obtain mixed powder, performing first vacuum hot-pressing sintering to obtain a silicon / aluminum composite material blank, then performing vacuum pressureless high-temperature sintering, and then performing second vacuum hot-pressing sintering to obtain the high-thermal-conductivity silicon / aluminum composite material. The method can be used for preparing the silicon / aluminum composite material for electronic packaging, the prepared material has high thermal conductivity and high density, the used process equipment is simple, and the material can be produced on a large scale.

Description

Technical Field

[0001] This invention belongs to the field of silicon / aluminum composite material technology, specifically relating to a high thermal conductivity silicon / aluminum composite material, its preparation method, and its application. Background Technology

[0002] Traditional metal packaging materials mainly include Al, Cu, steel, Kovar alloys, and W / Cu, Mo / Cu, etc., which can be made into shells, bases, or heat sinks for hermetic packaging in aerospace and other fields. With the continuous development of the semiconductor industry, higher requirements have been placed on heat dissipation materials for electronic packaging. These traditional metal packaging materials also face significant challenges, such as insufficient thermal conductivity, high specific gravity, and mismatch between their coefficient of thermal expansion and the chip's properties.

[0003] Therefore, metal matrix composites with excellent comprehensive properties have become a research hotspot in the field of electronic packaging materials, especially silicon / aluminum composites (also known as high-silicon aluminum alloys). Sandvik of Sweden was an early adopter, developing the Osprey® CE alloy (Si... p Silicon / aluminum composites have become the world's first commercially available aluminum-based composite material, finding widespread application in microwave and radio frequency fields. Subsequently, extensive research has been conducted on silicon / aluminum composites. For example, Chinese invention patent CN114378281A discloses a preparation process for a high-strength, high-silicon aluminum alloy material. This process employs a spray forming technique, first melting the alloy raw material in a nitrogen atmosphere, then using a combination of a composite modifier and ultrasonic vibration to refine the primary silicon crystals. Before spray forming, an electrostatic treatment is applied, and the atomized alloy liquid forms a quasi-ingot, which is then subjected to intermittent hot isostatic pressing to achieve a third micro-refinement. The resulting high-strength, high-silicon aluminum alloy material exhibits a uniform internal structure and high density. However, this process suffers from expensive equipment and complex manufacturing processes. Another Chinese invention patent, CN109487130A, discloses an aluminum-silicon composite material for electronic packaging and its preparation method. The composition and mass percentage of this aluminum-silicon composite material are: Si 50-70%, with the balance being Al. The preparation method is as follows: After mixing the raw material powder, it is placed in an aluminum sleeve, placed in a preheated mold, and pressed at 800MPa-1100MPa under a vacuum degree ≤10. -1 The temperature is increased to 750-1000℃ at a rate of 1-5℃ / min, and held for 1-4 hours. This method for preparing aluminum-silicon composite materials for electronic packaging can be mass-produced. However, the thermal conductivity of the aluminum-silicon composite materials prepared by this method is insufficient, not exceeding 130 W / (m•K).

[0004] To address the problems existing in the prior art, this invention proposes a method for preparing high thermal conductivity silicon / aluminum composite materials based on the traditional vacuum hot pressing sintering process. This method can prepare silicon / aluminum composite materials for electronic packaging, producing materials with high thermal conductivity and high density. The process equipment used is simple and can be mass-produced. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the present invention aims to provide a high thermal conductivity silicon / aluminum composite material, its preparation method, and its application. Based on the traditional vacuum hot pressing sintering method, a high thermal conductivity silicon / aluminum composite material is prepared by first performing a vacuum hot pressing sintering, followed by vacuum pressureless high-temperature sintering and a second vacuum hot pressing sintering. The initially formed composite material blank is densified to improve the thermal conductivity of the silicon / aluminum composite material, thereby solving the problem that the thermal conductivity of silicon / aluminum composite materials prepared by the prior art is not high enough.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] This invention provides a method for preparing a high thermal conductivity silicon / aluminum composite material, comprising the following steps:

[0008] Silicon powder and aluminum powder are ball-milled to obtain a mixed powder, which is then subjected to a first vacuum hot-pressing sintering to obtain a silicon / aluminum composite material ingot. Subsequently, it is subjected to vacuum pressureless high-temperature sintering, followed by a second vacuum hot-pressing sintering to obtain a high thermal conductivity silicon / aluminum composite material.

[0009] In one embodiment, the mixed powder contains 27wt% to 50wt% silicon by mass fraction, with the remainder being aluminum.

[0010] In one embodiment, the silicon powder has a particle size of less than 300 mesh and a purity of ≥99.9%; the aluminum powder has a particle size of less than 100 mesh and a purity of ≥99.9%.

[0011] In one embodiment, the process of performing a vacuum hot pressing sintering is as follows:

[0012] The mixed powder is loaded into a mold and then placed in a vacuum hot press. The vacuum hot press is evacuated to less than 0.1 Pa, and nitrogen is introduced until the vacuum pressure inside the vacuum hot press is 1.2 × 10⁻⁶. 4 Pa ~ 1.5 × 10 4 After stopping at a pressure between Pa, the vacuum was evacuated to less than 0.1 Pa, and then nitrogen was introduced until the vacuum pressure inside the vacuum autoclave was 1.2 × 10⁻⁶ Pa. 4 Pa ~ 1.5 × 10 4 After Pa, heating begins, followed by a vacuum hot pressing sintering process.

[0013] The protective atmosphere for the vacuum hot pressing sintering was nitrogen, and the pressure was maintained at 1.2 × 10⁻⁶. 4 Pa ~ 1.5 × 10 4 Pa, heating rate of 10℃ / min, hot pressing temperature of 550℃, hot pressing pressure of 20~30MPa, and holding time of heat and pressure of 180min.

[0014] In one embodiment, the subsequent vacuum pressureless high-temperature sintering process is as follows:

[0015] The silicon / aluminum composite material ingot is loaded into a graphite crucible, and the gap between the silicon / aluminum composite material ingot and the graphite crucible is filled and compacted with alumina powder.

[0016] The graphite crucible was placed in a vacuum hot press furnace and heated to a vacuum of less than 0.1 Pa before heating began. Vacuum pressureless high-temperature sintering was carried out at a heating rate of 10℃ / min, a sintering temperature of 850℃, and a holding time of 200min.

[0017] In one embodiment, the alumina powder is alumina powder with a particle size of -60 μm.

[0018] In one embodiment, the process of performing secondary vacuum hot pressing sintering is as follows:

[0019] After the vacuum hot press furnace is evacuated to less than 0.1 Pa, heating begins at a rate of 10℃ / min. The hot pressing temperature is 550℃, the hot pressing pressure is 20-30 MPa, and the holding time is 120 min.

[0020] The present invention also provides a high thermal conductivity silicon / aluminum composite material prepared according to the preparation method of the high thermal conductivity silicon / aluminum composite material, wherein the thermal conductivity of the high thermal conductivity silicon / aluminum composite material is 150 W / (m·K) or higher.

[0021] In one embodiment, the silicon content in the high thermal conductivity silicon / aluminum composite material is 27wt%~50wt%.

[0022] The present invention also provides an application of the high thermal conductivity silicon / aluminum composite material prepared according to the preparation method of the high thermal conductivity silicon / aluminum composite material in electronic packaging.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] This invention provides a method for preparing a high thermal conductivity silicon / aluminum composite material. Based on a single vacuum hot-pressing sintering process, a combined process of vacuum pressureless high-temperature sintering and a second vacuum hot-pressing sintering is introduced. Vacuum pressureless high-temperature sintering is a liquid-phase sintering process, with aluminum as the liquid phase and silicon as the solid phase. The liquid phase formed by aluminum powder generates capillary forces, acting as a binder to fill the voids in the billet formed by the single vacuum hot-pressing sintering, repairing defects and obtaining a denser solid. Simultaneously, high-temperature sintering further promotes the volatilization of organic matter, eliminates internal stress, and reduces porosity, significantly improving density and thermal conductivity. The second vacuum hot-pressing sintering, performed after vacuum pressureless high-temperature sintering, further optimizes the material's microstructure, eliminates residual stress and cracks within the silicon / aluminum composite material, reduces voids and defects in the billet, and improves the overall density and heat transfer efficiency. Furthermore, the second vacuum hot-pressing sintering promotes interfacial bonding between the aluminum matrix and silicon particles, contributing to improved tensile strength, hardness, and wear resistance.

[0025] In addition to the advantages of the preparation technology, the vacuum hot press furnace equipment used in this invention is mature and widely available, with high control precision, and has great advantages in terms of equipment cost and reliability, and the equipment investment is not high in terms of large-scale production.

[0026] This invention can prepare silicon / aluminum composite materials with a silicon content of 27wt%~50wt%. The preparation process is mature, the equipment used has cost advantages, the prepared material has a high degree of densification, and the thermal conductivity can be stably reached above 150 W / (m·K). As a thermal management material, it can be widely used in communication equipment, automotive electronics, aerospace and other fields to meet the performance requirements of these fields for material thermal conductivity and strength. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the powder loading process of the present invention.

[0028] Figure 2 This is a flowchart illustrating the preparation technology of the present invention.

[0029] Figure 3 The Si prepared according to the embodiments of the present invention P Microstructure diagram of (50wt%) / Al (50wt%). Detailed Implementation

[0030] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0031] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0032] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0033] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0034] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0035] This invention provides a method for preparing a high thermal conductivity silicon / aluminum composite material.

[0036] The raw materials used in the preparation are as follows: by mass fraction, the silicon content is 27wt%~50wt%, and the remainder is aluminum. The silicon powder used has a particle size of -300 mesh and a purity of ≥99.9%; the aluminum powder used has a particle size of -100 mesh and a purity of ≥99.9%.

[0037] The preparation method described above is as follows:

[0038] First, the raw materials were weighed, dried, and ball-milled. Then, a vacuum hot-pressing sintering process was performed under a nitrogen protective atmosphere, with the pressure maintained at 1.2 × 10⁻⁶. 4 Pa ~ 1.5 × 10 4 Pa, heating rate of 10℃ / min, hot pressing temperature of 550℃, hot pressing pressure of 20~30MPa, holding temperature and pressure for 180min;

[0039] After demolding, the billet is placed into a crucible for vacuum pressureless high-temperature sintering. The heating rate is 10℃ / min, the sintering temperature is 850℃, and the holding time is 200min.

[0040] After completion, the billet is put back into the hot pressing mold for secondary vacuum hot pressing sintering. The heating rate is 10℃ / min, the hot pressing temperature is 550℃, the hot pressing pressure is 20~30MPa, and the holding temperature and pressure are maintained for 120min.

[0041] The silicon / aluminum composite material prepared by the above method can achieve a thermal conductivity of over 150 W / (m·K) at room temperature. This material can be made into products such as tube shells and substrates for use in the field of electronic packaging.

[0042] Specifically, the above content, calculated by mass fraction, comprises 27wt%~50wt% high-purity silicon powder, with the remainder being high-purity aluminum powder. The high-purity silicon powder has a particle size of -300 mesh and a purity ≥99.9%; the high-purity aluminum powder has a particle size of -100 mesh and a purity ≥99.9%.

[0043] The heating rate of the first vacuum hot pressing sintering is 10℃ / min, the hot pressing temperature is 550℃, the hot pressing pressure is 20~30MPa, and the holding temperature and pressure is 180min.

[0044] The heating rate of the vacuum pressureless high-temperature sintering is 10℃ / min, the sintering temperature is 850℃, and the holding time is 200min.

[0045] The heating rate of the secondary vacuum hot pressing sintering is 10℃ / min, the hot pressing temperature is 550℃, the hot pressing pressure is 20~30MPa, and the holding temperature and pressure is 120min.

[0046] The nitrogen atmosphere is specifically achieved by evacuating the vacuum autoclave to less than 0.1 Pa and then filling it with nitrogen to stabilize the vacuum pressure at 1.2 × 10⁻⁶ Pa. 4 Pa ~ 1.5 × 10 4 Pa.

[0047] The silicon / aluminum composite materials prepared by the above method can all achieve a thermal conductivity of over 150 W / (m·K) at room temperature.

[0048] See Figure 2 In one specific embodiment, a method for preparing a high thermal conductivity silicon / aluminum composite material mainly includes the following steps:

[0049] (1) Weighing materials

[0050] The weights of high-purity silicon powder and high-purity aluminum powder were determined by calculation and the powders were weighed.

[0051] (2) Baking materials

[0052] High-purity silicon powder and high-purity aluminum powder were dried and degassed in a vacuum oven at 60°C for 24 hours.

[0053] (3) Mixing

[0054] The dried high-purity silicon powder and high-purity aluminum powder were loaded into a drum ball mill for ball milling and mixing. The ball-to-material ratio was 1:1, the rotation speed was 120 r / min, and the mixing time was 1 hour.

[0055] (4) Molding

[0056] like Figure 1 As shown, the mixed powder obtained in (3) is loaded into a hot press steel mold with an inner diameter of φ148mm, and then the steel mold is loaded into a vacuum hot press furnace.

[0057] (5) One-time vacuum hot pressing sintering

[0058] First, evacuate the hot press furnace to a vacuum level less than 0.1 Pa, then purge with nitrogen until the furnace vacuum pressure reaches 1.2 × 10⁻⁶. 4 Pa ~ 1.5 × 10 4 Stop when the pressure reaches 0.1 Pa, then evacuate to less than 0.1 Pa, and then purge with nitrogen until the furnace vacuum pressure reaches 1.2 × 10⁻⁶ Pa. 4 Pa ~ 1.5 × 10 4 Heating begins after Pa. The heating rate is 10℃ / min, the hot pressing temperature is 550℃, the hot pressing pressure is 20~30MPa, and the holding time is 180min.

[0059] (6) Unmolding and crucible loading

[0060] After one hot-pressing sintering, the material is allowed to cool naturally to room temperature. The mold is then removed for demolding to obtain a silicon / aluminum composite ingot. The ingot is then placed into a graphite crucible with an inner diameter of φ168mm, and the gap between the ingot and the graphite crucible is filled and compacted with -60μm alumina powder.

[0061] (7) Vacuum pressureless high-temperature sintering

[0062] The graphite crucible was placed in the hot press furnace and the vacuum was reduced to less than 0.1 Pa before heating began. The heating rate was 10℃ / min, the pressureless sintering temperature was 850℃, and the holding time was 200min.

[0063] (8) Removing the crucible and loading the mold

[0064] After vacuum pressureless high-temperature sintering, the ingot is naturally cooled to room temperature. The silicon / aluminum composite ingot is then removed from the graphite crucible, and any adhering alumina powder is removed. The ingot is then wrapped in graphite paper and placed into a hot-pressing steel mold, which is then placed into a vacuum hot-pressing furnace.

[0065] (9) Secondary vacuum hot pressing sintering

[0066] After the vacuum in the hot press furnace is evacuated to less than 0.1 Pa, heating begins at a rate of 10℃ / min. The hot pressing temperature is 550℃, the hot pressing pressure is 20-30 MPa, and the heat and pressure are maintained for 120 min.

[0067] (10) Remove from oven and demold

[0068] After the second hot pressing sintering is completed, the material is naturally cooled to room temperature. The mold is then removed and demolded to obtain the finished silicon / aluminum composite material ingot.

[0069] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0070] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0071] In the following embodiments, unless otherwise specified, all materials used can be obtained through ordinary channels; the testing methods used are conventional methods in the art.

[0072] Example 1

[0073] Step 1: According to the mass percentage, take 27wt% high-purity silicon powder as reinforcement and 73wt% high-purity aluminum powder as matrix. After calculation, weigh out 1.485kg of high-purity silicon powder and 4.165kg of high-purity aluminum powder.

[0074] Step 2: Place the high-purity silicon powder and high-purity aluminum powder weighed in Step 1 into a vacuum oven and keep them at 60℃ for 24 hours to dry and degas the high-purity silicon powder and aluminum powder.

[0075] Step 3: Load the dried high-purity silicon powder and high-purity aluminum powder into a drum ball mill for ball milling and mixing. The ball-to-material ratio is 1:1, the rotation speed is 120 r / min, and the mixing time is 1 hour.

[0076] Step 4: Load the mixed powder obtained in Step 3 into a hot press steel mold with an inner diameter of φ148mm, and then put the steel mold into a vacuum hot press furnace;

[0077] Step 5: First, evacuate the hot press furnace to a vacuum level less than 0.1 Pa, then fill it with nitrogen until the vacuum pressure inside the furnace reaches 1.5 × 10⁻⁶ Pa. 4 Stop after Pa, then evacuate to less than 0.1 Pa, then purge with nitrogen until the furnace vacuum pressure reaches 1.5 × 10⁻⁶ Pa. 4Heating begins after Pa. The heating rate is 10℃ / min, the hot pressing temperature is 550℃, the hot pressing pressure is 20MPa, and the holding time is 180min.

[0078] Step 6: After the first hot pressing sintering is completed, allow the material to cool naturally to room temperature. Remove the mold and demold to obtain a silicon / aluminum composite ingot. Place the ingot into a graphite crucible with an inner diameter of φ168mm, fill and compact the gap between the ingot and the graphite crucible with -60μm alumina powder.

[0079] Step 7: After loading the graphite crucible into the hot press furnace and evacuating it to a vacuum of less than 0.1 Pa, start heating at a heating rate of 10℃ / min, with a pressureless sintering temperature of 850℃ and a holding time of 200 min.

[0080] Step 8: After vacuum pressureless high-temperature sintering, allow the material to cool naturally to room temperature. Remove the silicon / aluminum composite ingot from the graphite crucible and remove any adhering alumina powder. Wrap the ingot in graphite paper and place it into a hot-pressing steel mold, then place the hot-pressing steel mold into a vacuum hot-pressing furnace.

[0081] Step 9: After evacuating the hot press furnace to a vacuum level of less than 0.1 Pa, start heating at a rate of 10℃ / min, a hot pressing temperature of 550℃, a hot pressing pressure of 20MPa, and hold at the temperature and pressure for 120 min.

[0082] Step 10: After the secondary hot pressing and sintering is completed, allow the material to cool naturally to room temperature. Remove the mold and demold to obtain the finished silicon / aluminum composite ingot.

[0083] The thermal conductivity of the obtained silicon / aluminum composite material (AlSi27) was measured to be 186 W / (m·K).

[0084] Example 2

[0085] Step 1: According to the mass percentage, take 27 wt% high-purity silicon powder as reinforcement and 73 wt% high-purity aluminum powder as matrix. After calculation, weigh out 1.485 kg of high-purity silicon powder and 4.165 kg of high-purity aluminum powder.

[0086] Step 2: Place the high-purity silicon powder and high-purity aluminum powder weighed in Step 1 into a vacuum oven and keep them at 60℃ for 24 hours to dry and degas the high-purity silicon powder and aluminum powder.

[0087] Step 3: Load the dried high-purity silicon powder and high-purity aluminum powder into a drum ball mill for ball milling and mixing. The ball-to-material ratio is 1:1, the rotation speed is 120 r / min, and the mixing time is 1 hour.

[0088] Step 4: Load the mixed powder obtained in Step 3 into a hot press steel mold with an inner diameter of φ148mm, and then put the steel mold into a vacuum hot press furnace;

[0089] Step 5: First, evacuate the hot press furnace to a vacuum level less than 0.1 Pa, then fill it with nitrogen until the vacuum pressure inside the furnace reaches 1.5 × 10⁻⁶ Pa. 4 Stop after Pa, then evacuate to less than 0.1 Pa, then purge with nitrogen until the furnace vacuum pressure reaches 1.5 × 10⁻⁶ Pa. 4 Heating begins after Pa. The heating rate is 10℃ / min, the hot pressing temperature is 550℃, the hot pressing pressure is 20MPa, and the holding time is 180min.

[0090] Step 6: After the first hot pressing sintering is completed, allow the material to cool naturally to room temperature. Remove the mold and demold to obtain a silicon / aluminum composite ingot. Place the ingot into a graphite crucible with an inner diameter of φ168mm, fill and compact the gap between the ingot and the graphite crucible with -60μm alumina powder.

[0091] Step 7: After loading the graphite crucible into the hot press furnace and evacuating it to a vacuum of less than 0.1 Pa, start heating at a heating rate of 10℃ / min, with a pressureless sintering temperature of 850℃ and a holding time of 200 min.

[0092] Step 8: After vacuum pressureless high-temperature sintering, allow the material to cool naturally to room temperature. Remove the silicon / aluminum composite ingot from the graphite crucible and remove any adhering alumina powder. Wrap the ingot in graphite paper and place it into a hot-pressing steel mold, then place the hot-pressing steel mold into a vacuum hot-pressing furnace.

[0093] Step 9: After evacuating the hot press furnace to a vacuum level of less than 0.1 Pa, start heating at a rate of 10℃ / min, a hot pressing temperature of 550℃, a hot pressing pressure of 20MPa, and hold at the temperature and pressure for 120 min.

[0094] Step 10: After the secondary hot pressing and sintering is completed, allow the material to cool naturally to room temperature. Remove the mold and demold to obtain the finished silicon / aluminum composite ingot.

[0095] The thermal conductivity of the obtained silicon / aluminum composite material (AlSi27) was measured to be 189 W / (m·K).

[0096] Example 3

[0097] Step 1: According to the mass percentage, take 42wt% high-purity silicon powder as reinforcement and 58wt% high-purity aluminum powder as matrix. After calculation, weigh out 2.31kg of high-purity silicon powder and 3.34kg of high-purity aluminum powder.

[0098] Step 2: Place the high-purity silicon powder and high-purity aluminum powder weighed in Step 1 into a vacuum oven and keep them at 60℃ for 24 hours to dry and degas the high-purity silicon powder and aluminum powder.

[0099] Step 3: Load the dried high-purity silicon powder and high-purity aluminum powder into a drum ball mill for ball milling and mixing. The ball-to-material ratio is 1:1, the rotation speed is 120 r / min, and the mixing time is 1 hour.

[0100] Step 4: Load the mixed powder obtained in Step 3 into a hot press steel mold with an inner diameter of φ148mm, and then put the steel mold into a vacuum hot press furnace;

[0101] Step 5: First, evacuate the hot press furnace to a vacuum level less than 0.1 Pa, then fill it with nitrogen until the vacuum pressure inside the furnace reaches 1.3 × 10⁻⁶ Pa. 4 Stop after Pa, then evacuate to less than 0.1 Pa, then purge with nitrogen until the furnace vacuum pressure reaches 1.5 × 10⁻⁶ Pa. 4 Heating begins after Pa. The heating rate is 10℃ / min, the hot pressing temperature is 550℃, the hot pressing pressure is 25MPa, and the holding time is 180min.

[0102] Step 6: After the first hot pressing sintering is completed, allow the material to cool naturally to room temperature. Remove the mold and demold to obtain a silicon / aluminum composite ingot. Place the ingot into a graphite crucible with an inner diameter of φ168mm, fill and compact the gap between the ingot and the graphite crucible with -60μm alumina powder.

[0103] Step 7: After loading the graphite crucible into the hot press furnace and evacuating it to a vacuum of less than 0.1 Pa, start heating at a heating rate of 10℃ / min, with a pressureless sintering temperature of 850℃ and a holding time of 200 min.

[0104] Step 8: After vacuum pressureless high-temperature sintering, allow the material to cool naturally to room temperature. Remove the silicon / aluminum composite ingot from the graphite crucible and remove any adhering alumina powder. Wrap the ingot in graphite paper and place it into a hot-pressing steel mold, then place the hot-pressing steel mold into a vacuum hot-pressing furnace.

[0105] Step 9: After evacuating the hot press furnace to a vacuum level of less than 0.1 Pa, start heating at a rate of 10℃ / min, a hot pressing temperature of 550℃, a hot pressing pressure of 25MPa, and hold at the temperature and pressure for 120 min.

[0106] Step 10: After the secondary hot pressing and sintering is completed, allow the material to cool naturally to room temperature. Remove the mold and demold to obtain the finished silicon / aluminum composite ingot.

[0107] The thermal conductivity of the obtained silicon / aluminum composite material (AlSi42) was found to be 180 W / (m·K).

[0108] Example 4

[0109] Step 1: According to the mass percentage, take 42wt% high-purity silicon powder as reinforcement and 58wt% high-purity aluminum powder as matrix. After calculation, weigh out 2.31kg of high-purity silicon powder and 3.34kg of high-purity aluminum powder.

[0110] Step 2: Place the high-purity silicon powder and high-purity aluminum powder weighed in Step 1 into a vacuum oven and keep them at 60℃ for 24 hours to dry and degas the high-purity silicon powder and aluminum powder.

[0111] Step 3: Load the dried high-purity silicon powder and high-purity aluminum powder into a drum ball mill for ball milling and mixing. The ball-to-material ratio is 1:1, the rotation speed is 120 r / min, and the mixing time is 1 hour.

[0112] Step 4: Load the mixed powder obtained in Step 3 into a hot press steel mold with an inner diameter of φ148mm, and then put the steel mold into a vacuum hot press furnace;

[0113] Step 5: First, evacuate the hot press furnace to a vacuum level less than 0.1 Pa, then fill it with nitrogen until the vacuum pressure inside the furnace reaches 1.3 × 10⁻⁶ Pa. 4 Stop after Pa, then evacuate to less than 0.1 Pa, then purge with nitrogen until the furnace vacuum pressure reaches 1.5 × 10⁻⁶ Pa. 4 Heating begins after Pa. The heating rate is 10℃ / min, the hot pressing temperature is 550℃, the hot pressing pressure is 25MPa, and the holding time is 180min.

[0114] Step 6: After the first hot pressing sintering is completed, allow the material to cool naturally to room temperature. Remove the mold and demold to obtain a silicon / aluminum composite ingot. Place the ingot into a graphite crucible with an inner diameter of φ168mm, fill and compact the gap between the ingot and the graphite crucible with -60μm alumina powder.

[0115] Step 7: After loading the graphite crucible into the hot press furnace and evacuating it to a vacuum of less than 0.1 Pa, start heating at a heating rate of 10℃ / min, with a pressureless sintering temperature of 850℃ and a holding time of 200 min.

[0116] Step 8: After vacuum pressureless high-temperature sintering, allow the material to cool naturally to room temperature. Remove the silicon / aluminum composite ingot from the graphite crucible and remove any adhering alumina powder. Wrap the ingot in graphite paper and place it into a hot-pressing steel mold, then place the hot-pressing steel mold into a vacuum hot-pressing furnace.

[0117] Step 9: After evacuating the hot press furnace to a vacuum level of less than 0.1 Pa, start heating at a rate of 10℃ / min, a hot pressing temperature of 550℃, a hot pressing pressure of 25MPa, and hold at the temperature and pressure for 120 min.

[0118] Step 10: After the secondary hot pressing and sintering is completed, allow the material to cool naturally to room temperature. Remove the mold and demold to obtain the finished silicon / aluminum composite ingot.

[0119] The thermal conductivity of the obtained silicon / aluminum composite material (AlSi42) was measured to be 182 W / (m·K).

[0120] Example 5

[0121] Step 1: According to the mass percentage, take 50wt% high-purity silicon powder as reinforcement and 50wt% high-purity aluminum powder as matrix. After calculation, weigh out 2.75kg of high-purity silicon powder and 2.90kg of high-purity aluminum powder.

[0122] Step 2: Place the high-purity silicon powder and high-purity aluminum powder weighed in Step 1 into a vacuum oven and keep them at 60℃ for 24 hours to dry and degas the high-purity silicon powder and aluminum powder.

[0123] Step 3: Load the dried high-purity silicon powder and high-purity aluminum powder into a drum ball mill for ball milling and mixing. The ball-to-material ratio is 1:1, the rotation speed is 120 r / min, and the mixing time is 1 hour.

[0124] Step 4: Load the mixed powder obtained in Step 3 into a hot press steel mold with an inner diameter of φ148mm, and then put the steel mold into a vacuum hot press furnace;

[0125] Step 5: First, evacuate the hot press furnace to a vacuum level less than 0.1 Pa, then fill it with nitrogen until the vacuum pressure inside the furnace reaches 1.2 × 10⁻⁶ Pa. 4 Stop after Pa, then evacuate to less than 0.1 Pa, then purge with nitrogen until the furnace vacuum pressure reaches 1.5 × 10⁻⁶ Pa. 4 Heating begins after Pa. The heating rate is 10℃ / min, the hot pressing temperature is 550℃, the hot pressing pressure is 30MPa, and the holding time is 180min.

[0126] Step 6: After the first hot pressing sintering is completed, allow the material to cool naturally to room temperature. Remove the mold and demold to obtain a silicon / aluminum composite ingot. Place the ingot into a graphite crucible with an inner diameter of φ168mm, fill and compact the gap between the ingot and the graphite crucible with -60μm alumina powder.

[0127] Step 7: After loading the graphite crucible into the hot press furnace and evacuating it to a vacuum of less than 0.1 Pa, start heating at a heating rate of 10℃ / min, with a pressureless sintering temperature of 850℃ and a holding time of 200 min.

[0128] Step 8: After vacuum pressureless high-temperature sintering, allow the material to cool naturally to room temperature. Remove the silicon / aluminum composite ingot from the graphite crucible and remove any adhering alumina powder. Wrap the ingot in graphite paper and place it into a hot-pressing steel mold, then place the hot-pressing steel mold into a vacuum hot-pressing furnace.

[0129] Step 9: After evacuating the hot press furnace to a vacuum level of less than 0.1 Pa, start heating at a rate of 10℃ / min, a hot pressing temperature of 550℃, a hot pressing pressure of 30MPa, and hold at the temperature and pressure for 120 min.

[0130] Step 10: After the secondary hot pressing and sintering is completed, allow the material to cool naturally to room temperature, remove the mold and demold to obtain the finished silicon / aluminum composite material ingot.

[0131] The thermal conductivity of the obtained silicon / aluminum composite material (AlSi50) was measured to be 153 W / (m·K).

[0132] Example 6

[0133] Step 1: According to the mass percentage, take 50wt% high-purity silicon powder as reinforcement and 50wt% high-purity aluminum powder as matrix. After calculation, weigh out 2.75kg of high-purity silicon powder and 2.90kg of high-purity aluminum powder.

[0134] Step 2: Place the high-purity silicon powder and high-purity aluminum powder weighed in Step 1 into a vacuum oven and keep them at 60℃ for 24 hours to dry and degas the high-purity silicon powder and aluminum powder.

[0135] Step 3: Load the dried high-purity silicon powder and high-purity aluminum powder into a drum ball mill for ball milling and mixing. The ball-to-material ratio is 1:1, the rotation speed is 120 r / min, and the mixing time is 1 hour.

[0136] Step 4: Load the mixed powder obtained in Step 3 into a hot press steel mold with an inner diameter of φ148mm, and then put the steel mold into a vacuum hot press furnace;

[0137] Step 5: First, evacuate the hot press furnace to a vacuum level less than 0.1 Pa, then fill it with nitrogen until the vacuum pressure inside the furnace reaches 1.2 × 10⁻⁶ Pa. 4 Stop after Pa, then evacuate to less than 0.1 Pa, then purge with nitrogen until the furnace vacuum pressure reaches 1.5 × 10⁻⁶ Pa. 4 Heating begins after Pa. The heating rate is 10℃ / min, the hot pressing temperature is 550℃, the hot pressing pressure is 30MPa, and the holding time is 180min.

[0138] Step 6: After the first hot pressing sintering is completed, allow the material to cool naturally to room temperature. Remove the mold and demold to obtain a silicon / aluminum composite ingot. Place the ingot into a graphite crucible with an inner diameter of φ168mm, fill and compact the gap between the ingot and the graphite crucible with -60μm alumina powder.

[0139] Step 7: After loading the graphite crucible into the hot press furnace and evacuating it to a vacuum of less than 0.1 Pa, start heating at a heating rate of 10℃ / min, with a pressureless sintering temperature of 850℃ and a holding time of 200 min.

[0140] Step 8: After vacuum pressureless high-temperature sintering, allow the material to cool naturally to room temperature. Remove the silicon / aluminum composite ingot from the graphite crucible and remove any adhering alumina powder. Wrap the ingot in graphite paper and place it into a hot-pressing steel mold, then place the hot-pressing steel mold into a vacuum hot-pressing furnace.

[0141] Step 9: After evacuating the hot press furnace to a vacuum level of less than 0.1 Pa, start heating at a rate of 10℃ / min, a hot pressing temperature of 550℃, a hot pressing pressure of 30MPa, and hold at the temperature and pressure for 120 min.

[0142] Step 10: After the secondary hot pressing and sintering is completed, allow the material to cool naturally to room temperature. Remove the mold and demold to obtain the finished silicon / aluminum composite ingot.

[0143] See Figure 3 Si prepared in the middle example P Microstructure of (50wt%) / Al (50wt%), where the dark part is silicon phase and the light part is aluminum phase.

[0144] The thermal conductivity of the obtained silicon / aluminum composite material (AlSi50) was measured to be 155 W / (m·K).

[0145]

[0146] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for preparing a high thermal conductivity silicon / aluminum composite material, characterized in that, Includes the following steps: Silicon powder and aluminum powder are ball-milled to obtain a mixed powder, which is then subjected to a first vacuum hot-pressing sintering to obtain a silicon / aluminum composite material ingot. Subsequently, it is subjected to vacuum pressureless high-temperature sintering, followed by a second vacuum hot-pressing sintering to obtain a high thermal conductivity silicon / aluminum composite material. By mass fraction, the silicon content in the mixed powder is 27wt%~50wt%, with the remainder being aluminum. The process of performing a vacuum hot pressing sintering is as follows: The mixed powder is loaded into a mold and then placed in a vacuum hot press. The vacuum hot press is evacuated to less than 0.1 Pa, and nitrogen is introduced until the vacuum pressure inside the vacuum hot press is 1.2 × 10⁻⁶. 4 Pa ~ 1.5 × 10 4 After stopping at a pressure between Pa, the vacuum was evacuated to less than 0.1 Pa, and then nitrogen was introduced until the vacuum pressure inside the vacuum autoclave was 1.2 × 10⁻⁶ Pa. 4 Pa ~ 1.5 × 10 4 After Pa, heating begins, followed by a vacuum hot pressing sintering process. The protective atmosphere for the vacuum hot pressing sintering was nitrogen, and the pressure was maintained at 1.2 × 10⁻⁶. 4 Pa ~ 1.5 × 10 4 Pa, heating rate of 10℃ / min, hot pressing temperature of 550℃, hot pressing pressure of 20~30MPa, and holding time of heat and pressure of 180min; The subsequent vacuum pressureless high-temperature sintering process is as follows: The silicon / aluminum composite material ingot is loaded into a graphite crucible, and the gap between the silicon / aluminum composite material ingot and the graphite crucible is filled and compacted with alumina powder. The graphite crucible was placed in a vacuum hot press furnace and heated to a vacuum of less than 0.1 Pa before heating began. Vacuum pressureless high-temperature sintering was carried out at a heating rate of 10℃ / min, a sintering temperature of 850℃, and a holding time of 200min.

2. The method for preparing the high thermal conductivity silicon / aluminum composite material according to claim 1, characterized in that, The silicon powder has a particle size of less than 300 mesh and a purity of ≥99.9%; the aluminum powder has a particle size of less than 100 mesh and a purity of ≥99.9%.

3. The method for preparing the high thermal conductivity silicon / aluminum composite material according to claim 1, characterized in that, The alumina powder is -60μm alumina powder.

4. The method for preparing the high thermal conductivity silicon / aluminum composite material according to claim 1, characterized in that, The process of performing secondary vacuum hot pressing sintering is as follows: After the vacuum hot press furnace is evacuated to less than 0.1 Pa, heating begins at a rate of 10℃ / min. The hot pressing temperature is 550℃, the hot pressing pressure is 20-30 MPa, and the holding time is 120 min.

5. A high thermal conductivity silicon / aluminum composite material prepared by the method according to any one of claims 1 to 4, characterized in that, The thermal conductivity of the high thermal conductivity silicon / aluminum composite material is above 150 W / (m·K).

6. The high thermal conductivity silicon / aluminum composite material according to claim 5, characterized in that, The silicon content in the high thermal conductivity silicon / aluminum composite material is 27wt%~50wt%.

7. The application of a high thermal conductivity silicon / aluminum composite material prepared by the method of any one of claims 1 to 4 in electronic packaging.

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