High-thermal-conductivity silicon / aluminum composite material as well as preparation method and application thereof

Abstract

The invention 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: carrying out ball-milling mixing on silicon powder and aluminum powder to prepare mixed powder, carrying out primary vacuum hot-pressed sintering to prepare a silicon / aluminum composite material billet, then carrying out vacuum non-pressure high-temperature sintering, and then carrying out secondary vacuum hot-pressed sintering to prepare 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 is high in heat conductivity and density, the used process equipment is simple, and large-scale production can be realized.

Description

Technical Field

[0001] The invention belongs to the technical field of silicon / aluminum composite materials, and specifically relates to a high thermal conductivity silicon / aluminum composite material and a preparation method and application thereof. Background Art

[0002] Traditional metal packaging materials mainly include Al, Cu, steel, Kovar alloy, W / Cu, Mo / Cu and other materials, which can be made into tube shells, bases or heat sinks, and used as airtight packaging in aerospace and other fields. With the continuous development of the semiconductor industry, higher requirements have been put forward for heat dissipation materials for electronic packaging. These traditional metal packaging materials also face huge challenges, such as insufficient thermal conductivity, high specific gravity, and mismatch between thermal expansion coefficient and chip.

[0003] Therefore, metal matrix composite materials with excellent comprehensive properties have become a research hotspot in the field of electronic packaging materials, especially the research and application of silicon / aluminum composite materials (also known as high-silicon aluminum alloys). Sandvik, a Swedish company, started early and developed Osprey® CE alloy (Si p / Al composite materials) have become the world's earliest aluminum-based composite materials to achieve commercial application, and have been widely used in the fields of microwaves, radio frequency, etc. Subsequently, a lot of research work has been carried out on silicon / aluminum composite materials. For example, the Chinese invention patent with publication number CN114378281A discloses a preparation process for a high-strength and high-silicon aluminum alloy material, which adopts a spray forming process. After the alloy raw material is melted in a nitrogen atmosphere, a composite modifier and ultrasonic vibration are combined to perform preliminary primary silicon refinement; before spray forming, an electric treatment is first performed, and after the atomized alloy liquid forms a quasi-ingot, an intermittent hot isostatic pressing treatment is performed to achieve the third refinement. The obtained high-strength and high-silicon aluminum alloy material has a uniform internal structure and high density. However, this process has the problems of expensive material preparation equipment and complex preparation process. Another Chinese invention patent with publication number CN109487130A discloses an aluminum-silicon composite material for electronic packaging and a preparation method thereof, and the components and mass percentages of each component contained in the aluminum-silicon composite material are: Si is 50-70%, and the balance is Al. The preparation method is as follows: the raw material powders are mixed, placed in an aluminum package, placed in a preheated mold and pressed at 800MPa-1100MPa, and the vacuum degree is ≤10 -1 Pa, heating to 750-1000°C at 1-5°C / min, and keeping warm for 1-4h. The preparation method of the aluminum-silicon composite material for electronic packaging can be mass-produced. However, the thermal conductivity of the aluminum-silicon composite material prepared by this method is less than 130W / (m•K).

[0004] In order to solve the problems existing in the prior art, the present invention proposes a method for preparing a high thermal conductivity silicon / aluminum composite material based on the preparation process of the traditional vacuum hot pressing sintering method. The method can prepare a silicon / aluminum composite material for electronic packaging, and the prepared material has high thermal conductivity and high density, and the process equipment used is simple and can be mass-produced. Summary of the invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a high thermal conductivity silicon / aluminum composite material and a preparation method and application thereof. On the basis of the traditional vacuum hot pressing sintering method, a high thermal conductivity silicon / aluminum composite material is prepared, that is, first a vacuum hot pressing sintering is performed, and then vacuum pressureless high temperature sintering and secondary vacuum hot pressing sintering are performed, and the initially formed composite material blank is densified to improve the thermal conductivity of the silicon / aluminum composite material, so as to solve the problem that the thermal conductivity of the silicon / aluminum composite material prepared by the prior art is not high enough.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention provides a method for preparing a high thermal conductivity silicon / aluminum composite material, comprising the following steps: Silicon powder and aluminum powder are ball-milled to obtain a mixed powder, which is subjected to a vacuum hot pressing sintering to obtain a silicon / aluminum composite material ingot, which is then subjected to vacuum pressureless high-temperature sintering, and then subjected to a second vacuum hot pressing sintering to obtain a high thermal conductivity silicon / aluminum composite material.

[0007] In one embodiment, the silicon content in the mixed powder is 27wt%-50wt% by mass, and the rest is aluminum.

[0008] In one embodiment, the particle size of the silicon powder is less than 300 mesh, and the purity is ≥99.9%; the particle size of the aluminum powder is less than 100 mesh, and the purity is ≥99.9%.

[0009] In one embodiment, the process of performing a vacuum hot pressing sintering is as follows: The mixed powder was loaded into a mold and then placed in a vacuum hot pressing furnace. The vacuum hot pressing furnace was evacuated to less than 0.1 Pa and filled with nitrogen until the vacuum pressure in the vacuum hot pressing furnace reached 1.2×10 4 Pa~1.5×10 4 Pa, and then evacuate to less than 0.1Pa, and then fill with nitrogen until the vacuum pressure in the vacuum hot press furnace is 1.2×10 4 Pa~1.5×10 4 After Pa, heating begins and vacuum hot pressing sintering is performed; The protective atmosphere of the vacuum hot pressing sintering was nitrogen, and the pressure was maintained at 1.2×10 4 Pa~1.5×10 4Pa, the heating rate is 10℃ / min, the hot pressing temperature is 550℃, the hot pressing pressure is 20-30MPa, and the heat preservation and pressure holding time is 180min.

[0010] In one embodiment, the process of performing vacuum pressureless high temperature sintering is as follows: Loading a silicon / aluminum composite ingot into a graphite crucible, and filling and compacting a gap between the silicon / aluminum composite ingot and the graphite crucible with alumina powder; The graphite crucible is placed in a vacuum hot pressing furnace and then heated after the vacuum is evacuated to less than 0.1 Pa, and vacuum pressureless high-temperature sintering is performed; the heating rate of the vacuum pressureless high-temperature sintering is 10°C / min, the sintering temperature is 850°C, and the insulation time is 200min.

[0011] In one embodiment, the alumina powder is -60 μm alumina powder.

[0012] In one embodiment, the process of performing secondary vacuum hot pressing sintering is as follows: The vacuum hot pressing furnace was evacuated to less than 0.1 Pa and then heating began. The heating rate was 10°C / min, the hot pressing temperature was 550°C, the hot pressing pressure was 20-30MPa, and the heat preservation and pressure holding time was 120min.

[0013] 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, and the thermal conductivity of the high thermal conductivity silicon / aluminum composite material is above 150W / (m·K).

[0014] In one embodiment, the silicon content in the high thermal conductivity silicon / aluminum composite material is 27wt%-50wt%.

[0015] The present invention also provides an application of a 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.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a preparation method of a high thermal conductivity silicon / aluminum composite material. On the basis of a primary vacuum hot pressing sintering, a combined process of vacuum pressureless high temperature sintering and secondary vacuum hot pressing sintering is introduced. Vacuum pressureless high temperature sintering is liquid phase sintering, in which aluminum is a liquid phase and silicon is a solid phase. The liquid phase formed by aluminum powder can generate capillary force, and is filled into the billet cavity formed by the primary vacuum hot pressing sintering as a binder to repair the billet defects and obtain a more compact entity. At the same time, high temperature sintering can continue to promote the volatilization of organic matter, eliminate stress in the billet, reduce porosity, and greatly improve the density and thermal conductivity of the material. The secondary vacuum hot pressing sintering carried out after the vacuum pressureless high temperature sintering can further optimize the microstructure of the material, eliminate the residual stress and cracks inside the silicon / aluminum composite material, reduce the body voids and defects, and improve the overall density and heat transfer efficiency of the material. In addition, the secondary vacuum hot pressing sintering can promote the interface bonding between the aluminum matrix and the silicon particles, which helps to improve the tensile strength, hardness and wear resistance of the material.

[0017] In addition to the advantages of the preparation technology, the vacuum hot pressing furnace used in the present invention is mature and common, has high control accuracy, and has great advantages in equipment cost and reliability, and the equipment investment in large-scale production is not high.

[0018] The present invention can prepare a silicon / aluminum composite material with a silicon content of 27wt% to 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 stably reach more than 150 W / (m·K). As a thermal management material, it can be widely used in communication equipment, automotive electronics, aerospace and other fields, meeting the performance requirements of these fields for material thermal conductivity and strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of powder filling mold of the present invention.

[0020] Figure 2 It is the preparation technology roadmap of the present invention.

[0021] Figure 3 Si prepared in the embodiment of the present invention P (50wt%) / Al(50wt%) microstructure diagram. DETAILED DESCRIPTION

[0022] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0023] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0024] In this article, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible sub-ranges and individual values ​​within the range (including integers and fractions).

[0025] In this document, unless otherwise specified, “includes,” “including,” “contains,” “has,” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0026] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0027] The invention provides a method for preparing a high thermal conductivity silicon / aluminum composite material.

[0028] The raw materials used for preparation are as follows: in terms of mass fraction, the silicon content is 27wt%~50wt%, and the rest is aluminum. The particle size of the silicon powder used is -300 mesh, and the purity is ≥99.9%; the particle size of the aluminum powder used is -100 mesh, and the purity is ≥99.9%.

[0029] The above preparation method is as follows: First, the raw materials were weighed, dried, and ball-milled to mix, and vacuum hot-pressed sintering was performed. The protective atmosphere was nitrogen and the pressure was maintained at 1.2×10 4 Pa~1.5×10 4 Pa, heating rate is 10℃ / min, hot pressing temperature is 550℃, hot pressing pressure is 20~30MPa, and heat preservation and pressure maintenance are 180min; After demoulding, the ingot is placed in a crucible for vacuum pressureless high-temperature sintering, with a heating rate of 10°C / min, a sintering temperature of 850°C, and a heat preservation time of 200min; After completion, the ingot is loaded into the hot pressing mold again for secondary vacuum hot pressing sintering, with a heating rate of 10°C / min, a hot pressing temperature of 550°C, a hot pressing pressure of 20-30MPa, and heat and pressure maintenance for 120min.

[0030] The silicon / aluminum composite material prepared by the above preparation method can achieve a thermal conductivity of more than 150 W / (m·K) at room temperature. The material can be made into products such as tube shells and substrates for application in the field of electronic packaging.

[0031] Specifically, the above content is calculated by mass fraction, high-purity silicon powder accounts for 27wt%~50wt%, and the rest is high-purity aluminum powder. The particle size of the high-purity silicon powder is -300 mesh, and the purity is ≥99.9%; the particle size of the high-purity aluminum powder is -100 mesh, and the purity is ≥99.9%.

[0032] The heating rate of the primary vacuum hot pressing sintering is 10°C / min, the hot pressing temperature is 550°C, the hot pressing pressure is 20-30MPa, and the heat and pressure are maintained for 180min; The vacuum pressureless high temperature sintering has a heating rate of 10°C / min, a sintering temperature of 850°C, and a heat preservation time of 200min; The heating rate of the secondary vacuum hot pressing sintering is 10°C / min, the hot pressing temperature is 550°C, the hot pressing pressure is 20-30MPa, and the heat and pressure are kept for 120min; The nitrogen atmosphere is specifically to evacuate the vacuum hot pressing furnace to less than 0.1 Pa, and fill it with nitrogen to stabilize the vacuum pressure at 1.2×10 4 Pa~1.5×10 4 Pa.

[0033] The thermal conductivity of the silicon / aluminum composite material prepared by the above preparation method can reach above 150 W / (m·K) at room temperature.

[0034] See also Figure 2 In a specific embodiment, a method for preparing a high thermal conductivity silicon / aluminum composite material mainly comprises the following steps: (1) Weighing Determine the weight of high-purity silicon powder and high-purity aluminum powder by calculation and weigh the powder; (2) Baking ingredients In a vacuum oven, keep the temperature at 60°C for 24 hours to dry and exhaust the high-purity silicon powder and high-purity aluminum powder; (3) Mixing The dried high-purity silicon powder and high-purity aluminum powder were placed in a drum ball mill for ball milling and mixing, with a ball-to-material ratio of 1:1, a rotation speed of 120 r / min, and a mixing time of 1 h.

[0035] (4) Moulding like Figure 1 As shown, the mixed powder obtained in (3) is loaded into a hot pressing steel mold with an inner diameter of φ148 mm, and then the steel mold is loaded into a vacuum hot pressing furnace; (5) One-time vacuum hot pressing sintering First, the hot press furnace was evacuated to a vacuum of less than 0.1 Pa, and nitrogen was filled into the furnace until the vacuum pressure was 1.2×10 4 Pa~1.5×10 4 Pa, stop, evacuate to less than 0.1Pa, and then fill with nitrogen until the vacuum pressure in the furnace is 1.2×10 4 Pa~1.5×10 4 Heating started after 3000 Pa. The heating rate was 10℃ / min, the hot pressing temperature was 550℃, the hot pressing pressure was 20~30MPa, and the heat and pressure were kept for 180min; (6) Demolding and loading crucible After the primary hot pressing sintering is completed, the mixture is naturally cooled to room temperature, and the mold is taken out for demoulding to obtain a silicon / aluminum composite material ingot. The ingot is placed in a graphite crucible with an inner diameter of φ168 mm, and the gap between the ingot and the graphite crucible is filled and compacted with -60 μm alumina powder.

[0036] (7) Vacuum pressureless high temperature sintering Put the graphite crucible into the hot pressing furnace and start heating after the vacuum is less than 0.1Pa, the heating rate is 10℃ / min, the pressureless sintering temperature is 850℃, and the temperature is kept for 200min; (8) Remove the crucible and install the mold After vacuum pressureless high temperature sintering, naturally cool to room temperature, take out the silicon / aluminum composite material ingot from the graphite crucible, and remove the alumina powder on it. Wrap the ingot with graphite paper and put it into the hot pressing steel mold, and then put the hot pressing steel mold into the vacuum hot pressing furnace; (9) Secondary vacuum hot pressing sintering The hot pressing furnace was vacuumed to less than 0.1Pa and then heating was started. The heating rate was 10℃ / min, the hot pressing temperature was 550℃, the hot pressing pressure was 20-30MPa, and the temperature and pressure were kept for 120min. (10) Demolding After the secondary hot pressing and sintering, the mixture is naturally cooled to room temperature, the mold is taken out and demoulded to obtain a finished silicon / aluminum composite material ingot.

[0037] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0038] The following examples use conventional instruments and equipment in the art. The experimental methods in the following examples that do not specify specific conditions are usually carried out under conventional conditions or under conditions recommended by the manufacturer. The various raw materials used in the following examples, unless otherwise specified, are conventional commercially available products, and their specifications are conventional specifications in the art. In the specification of the present invention and the following examples, unless otherwise specified, "%" means weight percentage, "part" means weight part, and ratio means weight ratio.

[0039] In the following examples, unless otherwise specified, all materials used can be obtained through common channels; and the test methods adopted are conventional methods in the art.

[0040] Example 1 Step 1: According to the mass percentage, 27wt% of high-purity silicon powder is used as the reinforcement, and 73wt% of high-purity aluminum powder is used as the matrix. After calculation, 1.485kg of high-purity silicon powder and 4.165kg of high-purity aluminum powder are weighed; Step 2: Place the high-purity silicon powder and high-purity aluminum powder weighed in step 1 in a vacuum oven, keep the temperature at 60° C. for 24 hours, and dry and exhaust the high-purity silicon powder and high-purity aluminum powder; Step 3: Place the dried high-purity silicon powder and high-purity aluminum powder into a drum ball mill for ball milling and mixing, with a ball-to-material ratio of 1:1, a rotation speed of 120 r / min, and a mixing time of 1 h.

[0041] Step 4: Place the mixed powder obtained in step 3 into a hot pressing steel mold with an inner diameter of φ148 mm, and then place the steel mold into a vacuum hot pressing furnace; Step 5: First, evacuate the hot press furnace to a vacuum of less than 0.1 Pa, and fill it with nitrogen until the vacuum pressure in the furnace is 1.5×10 4 Pa, and then evacuate to less than 0.1Pa, and then fill with nitrogen until the vacuum pressure in the furnace is 1.5×10 4 Heating started after 0.5 Pa. The heating rate was 10℃ / min, the hot pressing temperature was 550℃, the hot pressing pressure was 20MPa, and the heat and pressure were kept for 180min; Step 6: After the primary hot pressing sintering is completed, the mixture is naturally cooled to room temperature, and the mold is taken out for demoulding to obtain a silicon / aluminum composite material ingot. The ingot is placed in a graphite crucible with an inner diameter of φ168 mm, and the gap between the ingot and the graphite crucible is filled and compacted with -60 μm alumina powder.

[0042] Step 7: Place the graphite crucible into a hot press furnace and start heating after the vacuum is less than 0.1 Pa, with a heating rate of 10°C / min, a pressureless sintering temperature of 850°C, and keep warm for 200 minutes; Step 8: After vacuum pressureless high temperature sintering, cool naturally to room temperature, take out the silicon / aluminum composite material ingot from the graphite crucible, and remove the alumina powder on it. Wrap the ingot with graphite paper and put it into the hot pressing steel mold, and then put the hot pressing steel mold into the vacuum hot pressing furnace; Step 9: After the hot pressing furnace is vacuumed to less than 0.1 Pa, heating is started, the heating rate is 10°C / min, the hot pressing temperature is 550°C, the hot pressing pressure is 20MPa, and the heat and pressure are maintained for 120 minutes; Step 10: After the secondary hot pressing and sintering, the mixture is naturally cooled to room temperature, and the mold is taken out and demolded to obtain a finished silicon / aluminum composite material ingot.

[0043] After testing, the thermal conductivity of the obtained silicon / aluminum composite material (AlSi27) is 186W / (m·K).

[0044] Example 2 Step 1: According to the mass percentage, 27 wt% of high-purity silicon powder is used as a reinforcement, and 73 wt% of high-purity aluminum powder is used as a matrix. After calculation, 1.485 kg of high-purity silicon powder and 4.165 kg of high-purity aluminum powder are weighed; Step 2: Place the high-purity silicon powder and high-purity aluminum powder weighed in step 1 in a vacuum oven, keep the temperature at 60° C. for 24 hours, and dry and exhaust the high-purity silicon powder and high-purity aluminum powder; Step 3: Place the dried high-purity silicon powder and high-purity aluminum powder into a drum ball mill for ball milling and mixing, with a ball-to-material ratio of 1:1, a rotation speed of 120 r / min, and a mixing time of 1 h.

[0045] Step 4: Place the mixed powder obtained in step 3 into a hot pressing steel mold with an inner diameter of φ148 mm, and then place the steel mold into a vacuum hot pressing furnace; Step 5: First, evacuate the hot press furnace to a vacuum of less than 0.1 Pa, and fill it with nitrogen until the vacuum pressure in the furnace is 1.5×10 4 Pa, and then evacuate to less than 0.1Pa, and then fill with nitrogen until the vacuum pressure in the furnace is 1.5×10 4 Heating started after 0.5 Pa. The heating rate was 10℃ / min, the hot pressing temperature was 550℃, the hot pressing pressure was 20MPa, and the heat and pressure were kept for 180min; Step 6: After the primary hot pressing sintering is completed, the mixture is naturally cooled to room temperature, and the mold is taken out for demoulding to obtain a silicon / aluminum composite material ingot. The ingot is placed in a graphite crucible with an inner diameter of φ168 mm, and the gap between the ingot and the graphite crucible is filled and compacted with -60 μm alumina powder.

[0046] Step 7: Place the graphite crucible into a hot press furnace and start heating after the vacuum is less than 0.1 Pa, with a heating rate of 10°C / min, a pressureless sintering temperature of 850°C, and keep warm for 200 minutes; Step 8: After vacuum pressureless high temperature sintering, cool naturally to room temperature, take out the silicon / aluminum composite material ingot from the graphite crucible, and remove the alumina powder on it. Wrap the ingot with graphite paper and put it into the hot pressing steel mold, and then put the hot pressing steel mold into the vacuum hot pressing furnace; Step 9: After the hot pressing furnace is vacuumed to less than 0.1 Pa, heating is started, the heating rate is 10°C / min, the hot pressing temperature is 550°C, the hot pressing pressure is 20MPa, and the heat and pressure are maintained for 120 minutes; Step 10: After the secondary hot pressing and sintering, the mixture is naturally cooled to room temperature, and the mold is taken out and demolded to obtain a finished silicon / aluminum composite material ingot.

[0047] After testing, the thermal conductivity of the obtained silicon / aluminum composite material (AlSi27) is 189W / (m·K).

[0048] Example 3 Step 1: According to the mass percentage, 42wt% of high-purity silicon powder is used as the reinforcement, and 58wt% of high-purity aluminum powder is used as the matrix. After calculation, 2.31kg of high-purity silicon powder and 3.34kg of high-purity aluminum powder are weighed; Step 2: Place the high-purity silicon powder and high-purity aluminum powder weighed in step 1 in a vacuum oven, keep the temperature at 60° C. for 24 hours, and dry and exhaust the high-purity silicon powder and high-purity aluminum powder; Step 3: Place the dried high-purity silicon powder and high-purity aluminum powder into a drum ball mill for ball milling and mixing, with a ball-to-material ratio of 1:1, a rotation speed of 120 r / min, and a mixing time of 1 h.

[0049] Step 4: Place the mixed powder obtained in step 3 into a hot pressing steel mold with an inner diameter of φ148 mm, and then place the steel mold into a vacuum hot pressing furnace; Step 5: First, evacuate the hot press furnace to a vacuum of less than 0.1 Pa, and fill it with nitrogen until the vacuum pressure in the furnace is 1.3×10 4 Pa, and then evacuate to less than 0.1Pa, and then fill with nitrogen until the vacuum pressure in the furnace is 1.5×10 4 Heating started after 0.05 Pa. The heating rate was 10°C / min, the hot pressing temperature was 550°C, the hot pressing pressure was 25MPa, and the heat and pressure were kept for 180min; Step 6: After the primary hot pressing sintering is completed, the mixture is naturally cooled to room temperature, and the mold is taken out for demoulding to obtain a silicon / aluminum composite material ingot. The ingot is placed in a graphite crucible with an inner diameter of φ168 mm, and the gap between the ingot and the graphite crucible is filled and compacted with -60 μm alumina powder.

[0050] Step 7: Place the graphite crucible into a hot press furnace and start heating after the vacuum is less than 0.1 Pa, with a heating rate of 10°C / min, a pressureless sintering temperature of 850°C, and keep warm for 200 minutes; Step 8: After vacuum pressureless high temperature sintering, cool naturally to room temperature, take out the silicon / aluminum composite material ingot from the graphite crucible, and remove the alumina powder on it. Wrap the ingot with graphite paper and put it into the hot pressing steel mold, and then put the hot pressing steel mold into the vacuum hot pressing furnace; Step 9: After the hot pressing furnace is vacuumed to less than 0.1 Pa, heating is started, the heating rate is 10°C / min, the hot pressing temperature is 550°C, the hot pressing pressure is 25MPa, and the heat and pressure are maintained for 120 minutes; Step 10: After the secondary hot pressing and sintering, the mixture is naturally cooled to room temperature, and the mold is taken out and demolded to obtain a finished silicon / aluminum composite material ingot.

[0051] After testing, the thermal conductivity of the obtained silicon / aluminum composite material (AlSi42) is 180W / (m·K).

[0052] Example 4 Step 1: According to the mass percentage, 42wt% of high-purity silicon powder is used as the reinforcement, and 58wt% of high-purity aluminum powder is used as the matrix. After calculation, 2.31kg of high-purity silicon powder and 3.34kg of high-purity aluminum powder are weighed; Step 2: Place the high-purity silicon powder and high-purity aluminum powder weighed in step 1 in a vacuum oven, keep the temperature at 60° C. for 24 hours, and dry and exhaust the high-purity silicon powder and high-purity aluminum powder; Step 3: Place the dried high-purity silicon powder and high-purity aluminum powder into a drum ball mill for ball milling and mixing, with a ball-to-material ratio of 1:1, a rotation speed of 120 r / min, and a mixing time of 1 h.

[0053] Step 4: Place the mixed powder obtained in step 3 into a hot pressing steel mold with an inner diameter of φ148 mm, and then place the steel mold into a vacuum hot pressing furnace; Step 5: First, evacuate the hot press furnace to a vacuum of less than 0.1 Pa, and fill it with nitrogen until the vacuum pressure in the furnace is 1.3×10 4 Pa, and then evacuate to less than 0.1Pa, and then fill with nitrogen until the vacuum pressure in the furnace is 1.5×10 4 Heating started after 0.05 Pa. The heating rate was 10°C / min, the hot pressing temperature was 550°C, the hot pressing pressure was 25MPa, and the heat and pressure were kept for 180min; Step 6: After the primary hot pressing sintering is completed, the mixture is naturally cooled to room temperature, and the mold is taken out for demoulding to obtain a silicon / aluminum composite material ingot. The ingot is placed in a graphite crucible with an inner diameter of φ168 mm, and the gap between the ingot and the graphite crucible is filled and compacted with -60 μm alumina powder.

[0054] Step 7: Place the graphite crucible into a hot press furnace and start heating after the vacuum is less than 0.1 Pa, with a heating rate of 10°C / min, a pressureless sintering temperature of 850°C, and keep warm for 200 minutes; Step 8: After vacuum pressureless high temperature sintering, cool naturally to room temperature, take out the silicon / aluminum composite material ingot from the graphite crucible, and remove the alumina powder on it. Wrap the ingot with graphite paper and put it into the hot pressing steel mold, and then put the hot pressing steel mold into the vacuum hot pressing furnace; Step 9: After the hot pressing furnace is vacuumed to less than 0.1 Pa, heating is started, the heating rate is 10°C / min, the hot pressing temperature is 550°C, the hot pressing pressure is 25MPa, and the heat and pressure are maintained for 120 minutes; Step 10: After the secondary hot pressing and sintering, the mixture is naturally cooled to room temperature, and the mold is taken out and demolded to obtain a finished silicon / aluminum composite material ingot.

[0055] After testing, the thermal conductivity of the obtained silicon / aluminum composite material (AlSi42) is 182W / (m·K).

[0056] Example 5 Step 1: According to the mass percentage, 50wt% of high-purity silicon powder is used as the reinforcement, and 50wt% of high-purity aluminum powder is used as the matrix. After calculation, 2.75kg of high-purity silicon powder and 2.90kg of high-purity aluminum powder are weighed; Step 2: Place the high-purity silicon powder and high-purity aluminum powder weighed in step 1 in a vacuum oven, keep the temperature at 60° C. for 24 hours, and dry and exhaust the high-purity silicon powder and high-purity aluminum powder; Step 3: Place the dried high-purity silicon powder and high-purity aluminum powder into a drum ball mill for ball milling and mixing, with a ball-to-material ratio of 1:1, a rotation speed of 120 r / min, and a mixing time of 1 h.

[0057] Step 4: Place the mixed powder obtained in step 3 into a hot pressing steel mold with an inner diameter of φ148 mm, and then place the steel mold into a vacuum hot pressing furnace; Step 5: First, evacuate the hot press furnace to a vacuum of less than 0.1 Pa, and fill it with nitrogen until the vacuum pressure in the furnace is 1.2×10 4 Pa, and then evacuate to less than 0.1Pa, and then fill with nitrogen until the vacuum pressure in the furnace is 1.5×10 4 Heating started after 3000 Pa. The heating rate was 10℃ / min, the hot pressing temperature was 550℃, the hot pressing pressure was 30MPa, and the heat and pressure were kept for 180min; Step 6: After the primary hot pressing sintering is completed, the mixture is naturally cooled to room temperature, and the mold is taken out for demoulding to obtain a silicon / aluminum composite material ingot. The ingot is placed in a graphite crucible with an inner diameter of φ168 mm, and the gap between the ingot and the graphite crucible is filled and compacted with -60 μm alumina powder.

[0058] Step 7: Place the graphite crucible into a hot press furnace and start heating after the vacuum is less than 0.1 Pa, with a heating rate of 10°C / min, a pressureless sintering temperature of 850°C, and keep warm for 200 minutes; Step 8: After vacuum pressureless high temperature sintering, cool naturally to room temperature, take out the silicon / aluminum composite material ingot from the graphite crucible, and remove the alumina powder on it. Wrap the ingot with graphite paper and put it into the hot pressing steel mold, and then put the hot pressing steel mold into the vacuum hot pressing furnace; Step 9: After the hot pressing furnace is vacuumed to less than 0.1 Pa, heating is started, the heating rate is 10°C / min, the hot pressing temperature is 550°C, the hot pressing pressure is 30MPa, and the heat and pressure are maintained for 120 minutes; Step 10: After the secondary hot pressing and sintering, the mixture is naturally cooled to room temperature, and the mold is taken out and demolded to obtain a finished silicon / aluminum composite material ingot.

[0059] After testing, the thermal conductivity of the obtained silicon / aluminum composite material (AlSi50) is 153W / (m·K).

[0060] Example 6 Step 1: According to the mass percentage, 50wt% of high-purity silicon powder is used as the reinforcement, and 50wt% of high-purity aluminum powder is used as the matrix. After calculation, 2.75kg of high-purity silicon powder and 2.90kg of high-purity aluminum powder are weighed; Step 2: Place the high-purity silicon powder and high-purity aluminum powder weighed in step 1 in a vacuum oven, keep the temperature at 60° C. for 24 hours, and dry and exhaust the high-purity silicon powder and high-purity aluminum powder; Step 3: Place the dried high-purity silicon powder and high-purity aluminum powder into a drum ball mill for ball milling and mixing, with a ball-to-material ratio of 1:1, a rotation speed of 120 r / min, and a mixing time of 1 h.

[0061] Step 4: Place the mixed powder obtained in step 3 into a hot pressing steel mold with an inner diameter of φ148 mm, and then place the steel mold into a vacuum hot pressing furnace; Step 5: First, evacuate the hot press furnace to a vacuum of less than 0.1 Pa, and fill it with nitrogen until the vacuum pressure in the furnace is 1.2×10 4 Pa, and then evacuate to less than 0.1Pa, and then fill with nitrogen until the vacuum pressure in the furnace is 1.5×10 4 Heating started after 3000 Pa. The heating rate was 10℃ / min, the hot pressing temperature was 550℃, the hot pressing pressure was 30MPa, and the heat and pressure were kept for 180min; Step 6: After the primary hot pressing sintering is completed, the mixture is naturally cooled to room temperature, and the mold is taken out for demoulding to obtain a silicon / aluminum composite material ingot. The ingot is placed in a graphite crucible with an inner diameter of φ168 mm, and the gap between the ingot and the graphite crucible is filled and compacted with -60 μm alumina powder.

[0062] Step 7: Place the graphite crucible into a hot press furnace and start heating after the vacuum is less than 0.1 Pa, with a heating rate of 10°C / min, a pressureless sintering temperature of 850°C, and keep warm for 200 minutes; Step 8: After vacuum pressureless high temperature sintering, cool naturally to room temperature, take out the silicon / aluminum composite material ingot from the graphite crucible, and remove the alumina powder on it. Wrap the ingot with graphite paper and put it into the hot pressing steel mold, and then put the hot pressing steel mold into the vacuum hot pressing furnace; Step 9: After the hot pressing furnace is vacuumed to less than 0.1 Pa, heating is started, the heating rate is 10°C / min, the hot pressing temperature is 550°C, the hot pressing pressure is 30MPa, and the heat and pressure are maintained for 120 minutes; Step 10: After the secondary hot pressing and sintering, the mixture is naturally cooled to room temperature, and the mold is taken out and demolded to obtain a finished silicon / aluminum composite material ingot.

[0063] See also Figure 3 The Si prepared in the embodiment P (50wt%) / Al(50wt%) microstructure diagram, in which the dark part is the silicon phase and the light part is the aluminum phase.

[0064] After testing, the thermal conductivity of the obtained silicon / aluminum composite material (AlSi50) is 155W / (m·K).

[0065]

[0066] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a high thermal conductivity silicon / aluminum composite material, characterized in that: The following steps are involved: Silicon powder and aluminum powder are ball-milled to obtain a mixed powder, which is subjected to a vacuum hot pressing sintering to obtain a silicon / aluminum composite material ingot, which is then subjected to vacuum pressureless high-temperature sintering, and then subjected to a second vacuum hot pressing sintering to obtain a high thermal conductivity silicon / aluminum composite material.

2. The method for preparing the high thermal conductivity silicon / aluminum composite material according to claim 1, characterized in that: In terms of mass fraction, the silicon content in the mixed powder is 27wt%~50wt%, and the rest is aluminum.

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

4. The method for preparing the high thermal conductivity silicon / aluminum composite material according to claim 1, characterized in that: The process of performing vacuum hot pressing sintering is as follows: The mixed powder was loaded into a mold and then placed in a vacuum hot pressing furnace. The vacuum hot pressing furnace was evacuated to less than 0.1 Pa and filled with nitrogen until the vacuum pressure in the vacuum hot pressing furnace reached 1.2×10 4 Pa~1.5×10 4 Pa, and then evacuate to less than 0.1Pa, and then fill with nitrogen until the vacuum pressure in the vacuum hot press furnace is 1.2×10 4 Pa~1.5×10 4 After Pa, heating begins and vacuum hot pressing sintering is performed; The protective atmosphere of the vacuum hot pressing sintering was nitrogen, and the pressure was maintained at 1.2×10 4 Pa~1.5×10 4 Pa, the heating rate is 10℃ / min, the hot pressing temperature is 550℃, the hot pressing pressure is 20-30MPa, and the heat preservation and pressure holding time is 180min.

5. The method for preparing the high thermal conductivity silicon / aluminum composite material according to claim 1, characterized in that: The process of vacuum pressureless high temperature sintering is as follows: Loading a silicon / aluminum composite ingot into a graphite crucible, and filling and compacting a gap between the silicon / aluminum composite ingot and the graphite crucible with alumina powder; The graphite crucible is placed in a vacuum hot pressing furnace and then heated after the vacuum is evacuated to less than 0.1 Pa, and vacuum pressureless high-temperature sintering is performed; the heating rate of the vacuum pressureless high-temperature sintering is 10°C / min, the sintering temperature is 850°C, and the insulation time is 200min.

6. The method for preparing the high thermal conductivity silicon / aluminum composite material according to claim 5, characterized in that: The alumina powder is -60 μm alumina powder.

7. 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: The vacuum hot pressing furnace was evacuated to less than 0.1 Pa and then heating began. The heating rate was 10°C / min, the hot pressing temperature was 550°C, the hot pressing pressure was 20-30MPa, and the heat preservation and pressure holding time was 120min.

8. A high thermal conductivity silicon / aluminum composite material obtained by the method for preparing a high thermal conductivity silicon / aluminum composite material according to any one of claims 1 to 7, characterized in that: The thermal conductivity of the high thermal conductivity silicon / aluminum composite material is above 150 W / (m·K).

9. The high thermal conductivity silicon / aluminum composite material according to claim 8, characterized in that: The silicon content in the high thermal conductivity silicon / aluminum composite material is 27wt%-50wt%.

10. Use of a high thermal conductivity silicon / aluminum composite material prepared according to the method for preparing a high thermal conductivity silicon / aluminum composite material according to any one of claims 1 to 7 in electronic packaging.

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