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Prepared by powder metallurgy new Si-Al Electronic Packaging Materials

Author: CaiYang
Tutor: ZhengZiZuo
School: Central South University
Course: Materials Science
Keywords: Powder Metallurgy Liquid phase sintering Si-Al Electronic Packaging Materials Thermal performance Interface Moist
CLC: TF124
Type: Master's thesis
Year: 2004
Downloads: 368
Quote: 2
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Abstract


This paper is the first to explore the specific ways of using powder metallurgy liquid phase sintering method low thermal expansion, low density, high thermal conductivity of Si-Al Electronic Packaging. Mainly Si50wt%-Al system as an object of study. Focused on the specific process route (compacting pressure, sintering temperature, sintering time, cooling rate, heat treatment and the Si phase content) material formability and properties (density, thermal conductivity, thermal expansion coefficient). By metallography, X-ray, differential thermal analysis and scanning electron microscopy to analyze the internal structure of the material under the state of the system wettability, interfacial reactions and different processing. The main conclusions are as follows: 1. Excellent overall performance Si50wt%-Al electronic packaging materials completely prepared using powder metallurgy liquid phase sintering method. Its thermal conductivity of 131W / m · K; coefficient of thermal expansion reached 9.41-10.44 × 10 -6 / K; density reaches 2.48g/cm 3 . 2. Increasing the compacting pressure is advantageous for improving the powder compacts and sintered density as well as product performance. However, too much pressure causes the Si particles internally generated a large number of micro-cracks and defects, resulting in the decline in thermal conductivity of materials. 3. An appropriate increase in the sintering temperature and prolonging the sintering time can improve the wetting properties of the system, reducing the total number of the interface of the material within, as well as to ensure the formation of the network structure of the Al matrix communication, thereby enabling the increase in thermal conductivity performance. While at the same time bring the material thermal expansion coefficient increased, but overall, little sintering temperature and time on the performance of the thermal expansion coefficient of thermal expansion of the material depends mainly on the Si phase relative content. 4. Slow cooling will result in material internally too many eutectic material and coarse strip Si particles, causing a very negative impact on performance. The heat treatment is conducive to the elimination of the rapid cooling cell forming operation of the cell body retained a large number of lattice distortion and residual stress, the thermal conductivity of the material properties and thermal expansion properties are improved. 5. The densification mechanism Si-Al composite sintered at high temperature for the liquid phase flow - particles rearrangement mechanism and dissolution - precipitation mechanism. Rupture due to the surface of the alumina film of the Al powder in the high-temperature liquid-phase sintering process, resulting in the system there is a non-wetting to wetting of the transition temperature (950 ° C nearby). At this temperature for sintering, the system have been significantly improved wettability. Fresh Al oxide layer of the liquid and the surface of the Si particles interfacial reaction occurs, the extent of reaction with the sintering temperature and the sintering time and deepen.

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CLC: > Industrial Technology > Metallurgical Industry > Metallurgical Technology > Powder metallurgy (metal ceramic technology ) > Powder molding, sintering and post-processing
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