Preparation method of customizable functional composite material and electronic packaging shell

Abstract

The invention belongs to the technical field of electronic packaging materials, and discloses a preparation method of a customizable functional composite material and an electronic packaging shell. The method comprises the steps that according to performance requirements of different functional areas of a component, three-dimensional models and material components of the functional areas are designed respectively, and the materials are different metal-based composite materials; a laser deposition additive manufacturing technology is adopted, according to the three-dimensional model, corresponding metal matrix composite powder is switched, and a three-dimensional part biscuit containing all functional areas is integrally printed on the forming substrate layer by layer; and directly carrying out hot isostatic pressing treatment on the three-dimensional part biscuit without adopting a sheath so as to densify the three-dimensional part biscuit, thereby obtaining the customizable functional composite material. Different functional requirements of the electronic packaging shell are directly associated with specific material components and three-dimensional model design, and the most suitable material can be designed and prepared according to different functional areas in the component, so that multiple excellent properties are seamlessly integrated in a single component.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronic packaging materials, in particular to a preparation method of customizable functional composite material and an electronic packaging shell. BACKGROUND

[0002] With the rapid development of microelectronic technology towards high density, high frequency and high power, the comprehensive performance of electronic packaging materials is increasingly demanding. An ideal functional composite material not only needs to provide mechanical support and environmental protection for internal precision components, but also needs to consider multiple functions such as excellent thermal conductivity, electrical conductivity, low expansion, high strength, etc.

[0003] At present, the materials widely used in the field of electronic packaging, such as AlSi50, although the relative density can reach more than 99%, but its thermal conductivity (about 140 W / (m·K)) and bending strength (about 180 MPa) are still insufficient in high-power application, which is difficult to meet the development needs of multi-functional integration.

[0004] In terms of preparation process, the existing preparation method of functional composite material has significant limitations. The commonly used method is to prepare single material in steps, then use cold pressing to preliminarily form, then assemble and fasten through sleeve, and finally use hot isostatic pressing to composite. This method has the following inherent defects: (1) complicated process and low efficiency: the pre-processes such as design, preparation, vacuumizing and sealing of the sleeve are extremely complex, which seriously restricts the production efficiency and increases the manufacturing cost. (2) poor material distribution precision: due to the step-by-step preparation and assembly, the initial distribution position precision of the raw materials in the blank is low, which leads to large machining allowance. (3) it is difficult to ensure the consistency of performance: the large machining allowance easily leads to the deviation of the material distribution in each functional area of the final product from the design expectation, thereby affecting the reliability and consistency of the overall performance of the component.

[0005] In view of this, the present application is proposed. SUMMARY

[0006] The present application aims to at least solve one of the above technical problems, and provides a preparation method of customizable functional composite material and an electronic packaging shell.

[0007] To achieve the above purpose, the first technical solution adopted by the present application is: The preparation method of customizable functional composite material comprises the following steps: According to the performance requirements of different functional areas of the component, the three-dimensional model and the material composition of each functional area are designed respectively, and the material is different metal matrix composite material; Using laser deposition additive manufacturing technology, according to the three-dimensional model, the three-dimensional part blank containing all functional areas is integrally printed on the forming substrate layer by layer by switching the corresponding metal matrix composite material powder. The three-dimensional part green compact is not covered by a cover, and is directly subjected to hot isostatic pressing treatment to densify the three-dimensional part green compact, so as to obtain the customizable functional composite material.

[0008] Preferably, the metal matrix composite material comprises at least two of an aluminum alloy material, a silicon-aluminum alloy material, an aluminum-based diamond composite material and an aluminum-based silicon carbide composite material.

[0009] Preferably, in the silicon-aluminum alloy material used in the low-expansion functional area, the mass fraction of silicon is 12% to 80%. In the aluminum-based diamond composite material used in the high-thermal-conductivity functional area, the volume fraction of diamond is 40% to 65%. In the aluminum-based silicon carbide composite material used in the high-strength, high-wear-resistance or optical functional area, the volume fraction ratio of silicon carbide to aluminum is one of 30:70, 50:50 or 75:25.

[0010] Preferably, before the laser deposition additive manufacturing technology is used, the powder raw materials of the metal matrix composite materials are mixed in a ball mill, the revolution speed of the ball mill is 50 to 300 rpm, the rotation speed is 100 to 600 rpm, and the total ball milling time is 2 to 8 h.

[0011] Preferably, the process parameters of the hot isostatic pressing treatment are as follows: inert gas is used as a medium, the pressure is 100 to 200 MPa, the temperature is raised to 500 to 600 DEG C and is kept for 3 to 8 h.

[0012] Preferably, the specific steps of the hot isostatic pressing treatment include: vacuumizing to below 100 Pa, introducing argon to pressurize to 50 to 150 MPa, raising the temperature to 560 DEG C at a rate of 5 DEG C / min and keeping for 5 h, then lowering the temperature to 450 DEG C and keeping for 2 h, and then cooling in the furnace.

[0013] Preferably, after the hot isostatic pressing treatment, the step of stress relief aging heat treatment of the densified blank is further included: the blank is heated to 200 to 300 DEG C, kept for 8 to 12 h and then air-cooled.

[0014] Preferably, after the densification or stress relief aging heat treatment, the blank is subjected to mechanical processing to remove the excess amount and obtain the final size.

[0015] The second technical solution adopted in the application is as follows: An electronic packaging shell made of the customizable functional composite material prepared by the preparation method of any one of the above.

[0016] Preferably, the shell is an integrally formed structure, and at least includes a main structure composed of an aluminum alloy material, a low-expansion zone composed of a silicon-aluminum alloy material, a high-thermal-conductivity zone composed of an aluminum-based diamond composite material, and a high-strength zone and a high-wear-resistance zone composed of aluminum-based silicon carbide composite materials with different volume fractions.

[0017] Compared with the prior art, the present application has the following beneficial effects: The present application directly relates the different functional requirements (such as high thermal conductivity, low expansion, high wear resistance) of the electronic packaging shell to the specific material composition and three-dimensional model design. The most suitable material can be designed and prepared for the different functional zones inside the component, so as to seamlessly integrate multiple excellent performances in a single component, and solve the problem that the traditional single material cannot meet the multi-functional requirements.

[0018] The present application eliminates a series of complex processes such as "sleeve" design, preparation, vacuumizing and sealing which are indispensable in the traditional hot isostatic pressing process. The "sleeve-free" direct densification processing of the 3D printed green body is achieved, which greatly shortens the production cycle and reduces the equipment and operation costs, and is an important breakthrough in the process flow.

[0019] The present application adopts laser deposition 3D printing technology for preforming, which can accurately control the deposition position and shape of different functional materials according to the digital model, and realizes the accurate preparation of the size and position of the functional zone. The near-net forming technology makes the green body profile very close to the final product, the material utilization rate is high, the subsequent machining allowance is significantly reduced, and the problem of deviation of material performance caused by excessive machining is effectively avoided. The present application fully utilizes the advantages of the two technologies through the process combination of "3D printing preforming + hot isostatic pressing densification". The 3D printing realizes the flexible integration of complex structure and multiple materials, and the subsequent hot isostatic pressing processing completely eliminates the pores in the material under high temperature and high pressure, and makes the crystal grains rearrange, so that a composite material product with high density, uniform organization, excellent mechanical and thermal properties is finally obtained, and the comprehensive performance is much better than that of the material prepared by the traditional method. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The flowchart of the preparation method of the customizable functional composite material provided in the embodiment of the present application is shown. DETAILED DESCRIPTION

[0021] The present application will be described in detail below through embodiments, and the technical solutions of the present application are not limited to the specific embodiments listed below. It is necessary to point out here that the embodiments are only used to further illustrate the present application, and cannot be understood as a limitation on the protection scope of the present application. Some non-essential improvements and adjustments to the present application made by technical engineers in the field according to the content of the above-mentioned application are also regarded as falling within the protection scope of the present application.

[0022] Reference Figure 1 The first embodiment of the present application provides a method for preparing a customizable functional composite material, comprising the following steps: S1, according to the performance requirements of different functional areas of the component, the three-dimensional model and material composition of each functional area are designed respectively, and the material is different metal matrix composite material.

[0023] This step is the basis for realizing customization in the present application. The purpose is to break the limitation of using a single material to meet multiple functional requirements, according to the performance requirements of different areas of the component in actual working conditions, to carry out "tailor-made" precise design, and to provide digital model and material formula basis for subsequent integrated manufacturing.

[0024] "Functional area" refers to the local area on the same component that undertakes different physical or mechanical functions. For example, the area in contact with the chip in the electronic packaging shell needs high thermal conductivity to dissipate heat quickly; the area connected with the substrate needs low thermal expansion coefficient to match and avoid thermal stress; the structural support part needs high strength; and the sealing area may need high wear resistance.

[0025] "Designing three-dimensional model and material composition of each functional area respectively" means that the design process is parallel and related. Not only the macro three-dimensional shape of the component needs to be designed, but also the material attribute model of each functional area needs to be established independently, and its spatial position, geometric boundary, corresponding material chemical composition and volume fraction are determined.

[0026] As a specific example, first, according to the product functional requirements, the areas that need special performance are identified, such as material main structure, optical functional area, high strength functional area, high wear resistance functional area, high thermal conductivity functional area and low expansion functional area.

[0027] Then, using a general three-dimensional computer aided design software, the overall digital model of the component is created, and the geometric boundary of each functional area is accurately defined in the model. This is a conventional technical means in the art.

[0028] Finally, the most suitable metal matrix composites are specified for each functional zone. For example: for the main structure of the material pursuing lightweight and weldability, the design adopts 6063 aluminum alloy; for the low expansion functional zone requiring dimensional stability, the design adopts silicon aluminum alloy, with a mass fraction of 12%-80% of silicon; for the high thermal conductivity functional zone requiring rapid heat dissipation, the design adopts aluminum-based diamond composites, with a volume fraction of 40%-65% of diamond; for the high strength functional zone, high wear resistance functional zone or optical functional zone requiring mechanical properties, the design adopts aluminum-based silicon carbide composites, and the volume fraction ratio of silicon carbide to aluminum (e.g. 30:70, 50:50, 75:25) is adjusted to precisely control the performance to meet the needs of different emphases.

[0029] S2, using laser deposition additive manufacturing technology, according to the three-dimensional model, by switching the corresponding metal matrix composite powder, the three-dimensional part blank containing all the functional zones is printed on the forming substrate layer by layer.

[0030] The purpose of this step is to convert the design blueprint of S1 into a physical entity, and to achieve precise distribution and metallurgical combination of multiple different materials in three-dimensional space to form a complete part blank. It solves the problems of weak interface combination and poor positional accuracy caused by traditional step-by-step preparation and assembly.

[0031] "Laser deposition additive manufacturing technology" is a class of technologies that use laser as a heat source to melt and solidify powder materials synchronously, and to accumulate metal parts layer by layer. In some contexts, it can also be called directional energy deposition.

[0032] "Switching the corresponding metal matrix composite powder" means that multiple powder feeders are equipped on the printing equipment, and each powder feeder is loaded with powder of different composition. When the print head moves to different functional zones, the control system instructs the switching of the powder feeder, thereby changing the material composition of the deposition point.

[0033] "Integrated printing" means that the entire part containing multiple functional zones is completed in a continuous and uninterrupted printing process, and the functional zones are combined as a whole through metallurgical bonding, rather than mechanical connection later.

[0034] As a specific example, first, prepare the powder, and prepare the designed metal matrix composite powders respectively. As an optimal solution, the corresponding powders (such as aluminum powder, silicon powder, diamond particles, silicon carbide particles) are placed in a planetary ball mill according to the specified proportion for mixing. The ball milling parameters can be set to 50-300 rpm for revolution and 100-600 rpm for rotation, with a total time of 2-8 h, and the ball mill is alternately rotated forward and backward at regular intervals to ensure the uniformity of the powder mixture. This is a targeted parameter optimization of the conventional ball milling process in the art.

[0035] Then, the mixed powders are respectively loaded into multiple powder feeders of a 3D printing device; the powder feeders deliver the powders to a printing nozzle through inert carrier gas (such as argon); a high-power laser beam is focused on the interface between a forming substrate (or a printing substrate) and the powders as an energy source, and instantaneously melts the powders to form a tiny melt pool; a printing head moves according to a preset three-dimensional model path, and the melt pool rapidly cools and solidifies to form a layer of metal deposition; when the printing head moves to different functional areas, a control system switches the powder feeders in real time to change the types of the deposited materials. For example, when printing to a high-thermal-conductivity area, aluminum-based diamond powders are fed; when printing to a low-expansion area, silicon-aluminum alloy powders are switched.

[0036] After this step, the relative density of the obtained blank is usually about 90%, which provides a basis for subsequent densification treatment.

[0037] S3. The three-dimensional part blank is directly subjected to hot isostatic pressing treatment without a cover to densify the three-dimensional part blank, and a customizable functional composite material is obtained.

[0038] The purpose of this step is to eliminate internal pores, microcracks and other defects generated in the additive manufacturing process, so that the material reaches a state close to complete densification, thereby obtaining excellent mechanical and thermal properties and uniform microstructure. Through the cover-free process, the traditional hot isostatic pressing process is directly solved, which is complicated and inefficient.

[0039] The "hot isostatic pressing treatment" is a process of applying pressure to a workpiece placed in an isotropic ultra-high pressure medium (such as argon) at high temperature, which realizes the densification and diffusion bonding of the material by the combined action of high temperature and static high pressure.

[0040] "Without using a cover", traditionally, when performing hot isostatic pressing on powders or porous blanks, they need to be sealed in a specially designed metal or glass "cover" to prevent the pressure medium from entering the pores and maintain a vacuum environment. The present application omits this entire process.

[0041] "Directly", the 3D printed blank obtained in S2 is directly placed in the working chamber of the hot isostatic pressing furnace without any additional packaging or sealing.

[0042] As a specific example, first, the printed three-dimensional part blank is directly placed on the rack of the hot isostatic pressing furnace, after closing the furnace door, first, the furnace is pumped to high vacuum (for example, to 100 Pa or less), to remove the gas adsorbed on the surface of the furnace and the blank, to prevent oxidation or the formation of holes at high temperature. Then, high-purity argon gas is introduced into the furnace as a pressure medium, and pressurized to a predetermined pressure; the preferred pressure range of the present application is 50-150 MPa, while pressurizing or after pressurizing, the temperature is raised to a predetermined temperature at a controllable rate (for example, 5℃ / min). The preferred temperature range of the present application is 500-600℃, which is lower than the melting point of the material but sufficient to activate sufficient atomic diffusion and creep mechanism. Finally, after reaching the target temperature and pressure, it is necessary to keep warm and pressurized to provide sufficient time for the material to flow plastically, shrink and close the pores. The holding time can be adjusted within 3-8h according to the size of the part, and the preferred solution is to keep warm at 560℃ for 5h. Subsequently, the temperature can be controlled to decrease, for example, to 450℃ and then kept warm for 2h to stabilize the structure, and finally cooled to room temperature with the furnace.

[0043] Because the 3D printed blank itself has a density of about 90% and fewer internal connected pores, its surface is sufficient to block the invasion of the pressure medium to some extent, making the sleeveless process possible. Under high temperature and high pressure, the residual pores in the material are completely compacted, and firm bonding is formed between the grains through diffusion, finally obtaining a dense part with a relative density of up to 99.5% or more, while realizing the metallurgical bonding of materials in different functional zones.

[0044] In some preferred embodiments, after hot isostatic pressing, in order to further eliminate the internal stress that may be left in the material during manufacturing and densification, stress relief annealing (aging treatment) can be performed. This is a conventional means, and specifically the blank can be placed in a resistance furnace and heated to 200-300℃ (preferably 250℃), and then kept warm for 8-12h (preferably 10h) and then air cooled. Finally, according to the dimensional accuracy requirements of the final product, a small amount of excess material can be removed using conventional mechanical processing methods, and a customizable functional composite material component that meets all design performance requirements can be obtained.

[0045] The second embodiment of the present application provides an electronic packaging shell made by any of the aforementioned customizable functional composite material preparation methods.

[0046] The core feature of the electronic package housing of the present invention is that it is a single component integrally formed without mechanical connection interfaces, but internally composed of multiple different metal matrix composites, forming a macroscopic "structure-function" integrated body. Unlike the traditional housings assembled by brazing, screwing and other methods, the housing of the present invention is connected between the functional areas by metallurgical bonding, with high interface bonding strength, avoiding the failure risk caused by mismatch of thermal expansion coefficient, interface oxidation or fatigue, while having better air tightness and reliability.

[0047] The electronic package housing comprises at least one main structure and multiple functional areas. These areas are physically seamlessly connected, but have clear distinction in material composition. They include: material main structure, low expansion functional area, high thermal conductivity functional area, high strength functional area and high wear resistance functional area, optical functional area, the functions and material composition of each functional area are described as follows.

[0048] The material main structure provides the core mechanical support framework for the entire housing and ensures the lightweight and weldability of the structure to facilitate integration with other components. The material main structure is composed of aluminum alloy, preferably 6063 aluminum alloy. This material provides good comprehensive mechanical properties, low density and excellent processability, and is the basis for realizing the lightweight and overall structural integrity of the housing.

[0049] The low expansion functional area is customized to be placed at the location where it needs to be connected with chips, ceramic substrates or other low expansion elements. Its function is to provide a low thermal expansion coefficient similar to that of the matching elements, thereby minimizing thermal stress and preventing cracking or deformation when the temperature changes. This area is composed of silicon-aluminum alloy. Preferably, the mass fraction ratio of silicon to aluminum is 50:50. The high silicon content significantly reduces the overall thermal expansion coefficient of the material, enabling it to be well matched with semiconductor materials.

[0050] The high thermal conductivity functional area is customized to be placed under power devices or hot spots. Its function is to serve as an efficient heat management channel to rapidly spread or conduct the large amount of heat generated during operation laterally to the heat sink, thereby effectively reducing the chip junction temperature. This area is composed of aluminum-based diamond composite material. Preferably, the volume fraction ratio of diamond to aluminum is 60:40. Diamond is the material with the highest thermal conductivity in nature, and after being compounded with the aluminum matrix, it can obtain a thermal conductivity much higher than that of pure aluminum or traditional aluminum-silicon alloy.

[0051] High strength functional zones, usually located at positions where large mechanical stress or structural stiffness is required, such as corners of the housing, fastener mounting locations, etc. High wear resistance functional zones, usually located at contact surfaces where friction or plugging can occur, such as the edge of a connector socket, etc. Both of the above zones are composed of aluminum based silicon carbide composites. By adjusting the volume fraction of the reinforcing phase silicon carbide, the performance of the zones can be precisely controlled. For high strength functional zones, a composite with a volume fraction ratio of silicon carbide to aluminum of 50:50 is preferred, to achieve the best balance between toughness and strength. For high wear resistance functional zones, a composite with a volume fraction ratio of silicon carbide to aluminum of 75:25 is preferred, the high content of hard silicon carbide particles provides excellent wear resistance.

[0052] Optical functional zones, located at positions where optical windows or sensor channels are required. Their function is to provide specific surface properties (such as polishable to mirror surface), specific electromagnetic wave transmission / reflection performance, or thermal expansion matching with optical elements. The zones are composed of aluminum based silicon carbide composites, but a composite with a volume fraction ratio of silicon carbide to aluminum of 30:70 is preferred. The lower ceramic content makes the zones more easily subjected to precision cutting and polishing, to obtain high quality optical surfaces, while maintaining the stiffness and stability superior to pure metals.

[0053] The electronic package housing provided by the embodiments integrates a plurality of materials with different properties in three-dimensional space according to functional requirements, and achieves comprehensive performance that cannot be achieved by a single material. It not only inherits the firmness and air tightness of traditional metal housings, but also precisely distributes heat management, stress matching, wear resistance, and optical functions inside, so as to meet the needs of the next generation of high-power, high-density, and high-reliability microelectronic packages.

[0054] The above examples are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for producing a customizable functional composite material, characterized by, The method comprises the following steps: According to the performance requirements of different functional areas of the component, the three-dimensional model and material composition of each functional area are designed respectively, and the material is different metal matrix composites; Using laser deposition additive manufacturing technology, according to the three-dimensional model, by switching the corresponding metal matrix composite powder, the three-dimensional part blank containing all functional areas is printed on the forming substrate layer by layer; The three-dimensional part blank is directly subjected to hot isostatic pressing treatment without using a cover, so as to densify and obtain the customizable functional composite material.

2. The production method according to claim 1, wherein The metal matrix composite includes at least two of aluminum alloy material, silicon-aluminum alloy material, aluminum-based diamond composite material, and aluminum-based silicon carbide composite material.

3. The production method according to claim 2, wherein In the silicon-aluminum alloy material used in the low-expansion functional area, the mass fraction of silicon is 12%-80%; In the aluminum-based diamond composite material used in the high-thermal-conductivity functional area, the volume fraction of diamond is 40%-65%; In the aluminum-based silicon carbide composite material used in the high-strength, high-wear-resistance, or optical functional area, the volume fraction ratio of silicon carbide to aluminum is one of 30:70, 50:50, or 75:

25.

4. The production method according to claim 1, wherein Before using the laser deposition additive manufacturing technology, the powder raw materials of each metal matrix composite are mixed in a ball mill, the revolution speed of the ball mill is 50-300 rpm, the rotation speed is 100-600 rpm, and the total ball milling time is 2-8 h.

5. The production method according to claim 1, wherein The process parameters of the hot isostatic pressing treatment are as follows: using inert gas as medium, pressure is 100-200 MPa, temperature is raised to 500-600 ℃ and kept for 3-8 h.

6. The production method according to claim 5, wherein The specific steps of the hot isostatic pressing treatment include: vacuumizing to below 100 Pa, introducing argon to pressurize to 50-150 MPa, raising temperature to 560 ℃ at a rate of 5 ℃ / min and keeping for 5 h, then lowering temperature to 450 ℃ and keeping for 2 h, and then cooling down with the furnace.

7. The production method according to claim 1, wherein After the hot isostatic pressing treatment, a step of stress relief aging heat treatment of the densified blank is further included: heating the blank to 200-300 ℃, keeping for 8-12 h, and then air cooling.

8. The production method according to claim 1 or 7, wherein After the densification or stress relief aging heat treatment, the blank is subjected to mechanical processing to remove excess amount and obtain the final size.

9. An electronic package housing, characterized by The electronic packaging shell is made of the customizable functional composite material prepared by the method of any one of claims 1-8.

10. The electronic package enclosure of claim 9, wherein, The shell is an integrally formed structure, and at least includes a main body structure composed of aluminum alloy material, a low-expansion area composed of silicon-aluminum alloy material, a high-thermal-conductivity area composed of aluminum-based diamond composite material, and high-strength and high-wear-resistance areas composed of aluminum-based silicon carbide composite material with different volume fractions.

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