Silicon carbide particle reinforced aluminum matrix composites

It is a particle reinforced metal matrix composite, which uses Al alloy as the matrix, according to the design requirements, in a certain form, proportion and distribution state, and SiC particles as the reinforcement to form a multi-phase composite with obvious interface, which has the comprehensive superior properties that a single metal does not have. Chinese name aluminum silicon carbide foreign name AlSiC application field aerospace, microwave integrated circuit, power module Si content 70wt%, SiC volume accounting for 50% - 75%, AlSiC was developed earlier, and the theoretical description is relatively perfect. Some varieties took the lead in realizing the large-scale industrialization of electronic packaging materials, meeting the requirements that the integration degree of semiconductor chips increases along Moore's law, resulting in a sharp increase in chip calorific value The decline of service life and the development demand of "thin and micro" of electronic packaging. Especially in aerospace, microwave integrated circuits, power modules, military RF system chips and other packaging analysis, it has become an important trend in the application and development of packaging materials.

There are several kinds of reinforcements for encapsulating metal matrix composites, among which SiC is the most widely used because it has excellent thermal properties, mature technology and relatively low price as granular abrasive; On the other hand, particle reinforced materials are isotropic, which is most conducive to net forming. The properties of AlSiC mainly depend on the volume fraction (content), distribution and particle size of SiC, as well as the composition of Al alloy. According to the two-phase ratio or the heat treatment state of the composite, the thermophysical and mechanical properties of the material can be designed to meet the performance requirements of chip packaging. Among them, SiC volume fraction is particularly important. In practical application, AlSiC is in direct contact with chip or ceramic matrix, and CTE is required to match as much as possible. Therefore, the volume percentage Vol of SiC is usually 50% - 75%. In addition, AlSiC can coexist and integrate a variety of electronic packaging materials for packaging integration and develop other functions and applications. Cu based packaging material blocks with high performance and fast heat dissipation (Cu diamond, Cu graphite, Cu BeO, etc.) are successfully embedded into SiC preforms, and the coexisting integrated packaging substrate is fabricated by metal Al infiltration. In the process of AlSiC coexistence and integration, these expensive fast heat dissipation materials can be set in the most needed parts to reduce costs and expand production scale. The AlSiC flip chip system embedded with fast heat dissipation materials is being tested and evaluated. In addition, 48 alloy, Kovar, stainless steel and other materials can be integrated simultaneously. Such materials or inserts, leads, sealing rings, substrates, etc. can be inserted into SiC preforms before infiltration. In the AlSiC composite forming process, the coexistence integration can be completed economically to facilitate the laser connection of optoelectronic device packaging.

High silicon aluminum alloy sial packaging material with uniform internal structure, excellent performance and Si content up to 70wt% (weight percentage) was prepared by spray deposition technology. The CTE of high silicon aluminum alloy is matched with Si and GaAs. It can also be used in RF and microwave circuit packaging and aerospace electronic subsystem, and developed into a light metal packaging material. Aluminum silicon carbide (AlSiC) metal matrix thermal management composite is a special packaging material for electronic components. It mainly refers to the combination of aluminum and high volume fraction silicon carbide into a packaging material with low density, high thermal conductivity and low expansion coefficient, so as to solve the problem of thermal failure of electronic circuits.

Performance characteristics of AlSiC

■ AlSiC has high thermal conductivity (180 ~ 240W / MK) and adjustable thermal expansion coefficient (6.5 ~ 9.5 × 10-6 / k), so on the one hand, the thermal expansion coefficient of AlSiC is well matched with semiconductor chip and ceramic substrate, which can prevent fatigue failure, and even install the power chip directly on AlSiC substrate; On the other hand, the thermal conductivity of AlSiC is ten times that of Kovar alloy, and the heat generated by the chip can be dissipated in time. In this way, the reliability and stability of the whole component are greatly improved.

■ AlSiC is a composite material, and its thermal expansion coefficient and other properties can be adjusted by changing its composition. Therefore, the product can be designed flexibly according to the specific requirements of users, and can be truly tailored, which can not be achieved by traditional metal materials or ceramic materials.

■ AlSiC has the same density as aluminum, much lighter than copper and Kovar, less than one fifth of Cu / W. it is especially suitable for portable devices, aerospace and other weight sensitive fields.

■ the specific stiffness (stiffness divided by density) of AlSiC is the highest among all electronic materials: 3 times that of aluminum, 5 times that of W-Cu and Kovar, and 25 times that of copper. In addition, the seismic resistance of AlSiC is better than that of ceramics, so it is the first choice material in harsh environment (large vibration, such as aerospace, automobile and other fields).

■ AlSiC can be processed in large quantities, but the processing technology depends on the content of silicon carbide. It can be processed by EDM, diamond, laser, etc.

■ AlSiC can be nickel plated, gold, tin, etc., and its surface can also be anodized.

■ the metallized ceramic substrate can be brazed to the plated AlSiC substrate, and the printed circuit board core can be bonded to AlSiC with adhesive and resin.

■ AlSiC has good air tightness. However, the air tightness after packaging with metal or ceramic depends on the appropriate coating and welding.

■ the physical and mechanical properties of AlSiC are isotropic. Significance of using AlSiC materials

■ it can greatly improve the packaging performance of integrated circuits. The use of aluminum silicon carbide material for electronic packaging makes the package consistent with the thermal expansion of the chip, plays a good heat conduction function, and solves the problem of thermal failure of the circuit;

■ batch use of AlSiC materials can reduce the packaging cost. The company offers special discounts for long-term and large-scale orders, which is much cheaper than the current use of precious metal materials such as W-Cu and mo;

■ effectively improve the packaging technology level in China's aerospace, military, microwave and other power microelectronics fields, improve functions, reduce costs, and accelerate the evolution of China's aerospace and military products. For example, where Kovar material was used as the device packaging shell in the past, if the aluminum silicon carbide shell was replaced, the weight could be reduced to one-third of the original, and the thermal conductivity could be increased to ten times of the original.

■ the successful development of AlSiC packaging materials indicates that Chinese enterprises no longer play the role of a simple blue collar and processor in the packaging field, but have their own packaging leading products with independent technical core, which fills the domestic gap and is a huge technological progress in the packaging field; Using AlSiC produced by Xi'an chuangzheng new materials Co., Ltd. is to support national industry and contribute to localization in relevant fields.

■ superior performance makes AlSiC have broader performance than W-Cu, Mo, BeO, Kovar, Mo Cu, AlN, AlSi, Al2O3 and other current packaging materials, and AlSiC has wider application space than W-Cu, Mo, BeO, Kovar, Mo Cu, AlN, AlSi, Al2O3 and other current packaging materials. The performance of AlSiC material alsic7 brand density is 3.0 ± 0.05 g / cm3; Bending strength 400MPa volume fraction: 70 ± 3%, thermal conductivity: ≥ 180W / MK, specific heat at 20 ℃: 0.75j/gk, resistivity at 20 ℃: 2.1 x10-5 w · cm, linear expansion coefficient 8.0 ± 0.5x10-6 (50-150 ℃)

Application of AlSiC material, high power IGBT heat dissipation substrate; LED package lighting; Aerospace; Microelectronics; Shell packaging; Civil aircraft, high-speed rail and other fields