Advanced Materials for Thermal Management of Electronic Packaging by Xingcun Colin Tong

Author:Xingcun Colin Tong
Language: eng
Format: epub
Publisher: Springer New York, New York, NY

Summary

Ceramic composites are being actively developed in many research establishments primarily for structural and load-bearing applications. Fiber, whisker, or particulate reinforced composites can be made tougher and stronger than traditional unreinforced ceramics. Among the key factors responsible for the improved stress resistance are differences in Young’s moduli between the phases and the nature of the interaction at interfaces between matrix and the reinforcement. As user confidence continues to grow and as energy savings, increased productivity, and reduced maintenance are confirmed, the need has emerged for advanced ceramics with improved toughness. Discontinuous reinforced ceramic composites have partially filled this need, but their application is limited in both size and geometry, and their toughness is less than desired for a risk-adverse industry. Continuous fiber reinforced ceramic composites are viewed as the ultimate solution with many applications rapidly becoming commercially viable. Thermally conductive ceramic composites have been actively developed thermal management of electronic packaging. Fiber, whisker, particulate, or nanotube reinforced composites can be made tougher, stronger, and more effective for thermal management with tailored CTE. The desirable characteristics of CMCs include high-temperature stability, high thermal shock resistance, high hardness, high corrosion resistance, light weight, nonmagnetic and nonconductive properties, and versatility in providing unique engineering solutions. The combination of these characteristics makes CMCs attractive alternatives to thermal management of electronic packaging, particularly for high temperature electronic packaging system.

Of these, SiC fibers have been the most widely used because of their high strength, stiffness and thermal stability. SiC matrix CFCCs have been successfully demonstrated in a number of applications where a combination of high thermal conductivity, low thermal expansion, light weight, and good corrosion and wear resistance is desired. SiC matrix CFCCs can be fabricated using a variety of processes, fibers, and interface coatings. Fibers widely used for industrial applications where long life is desired include SiC or mullite. Processes available to fabricate SiC matrix CFCCs and the matrix composition formed include Sic, polymer infiltration (SiCN, SiC), nitride bonding (Si–SiC–Si3N4), and melt infiltration (Si–SiC). The interface coating can be either carbon or boron nitride with a protective overcoat of SiC or Si3N4.

SiC–diamond composites are composed of microcrystalline diamond held together by microcrystalline SiC. The thermal conductivity of the SiC–diamond composite spreader can reach around 600 W/m K, CET is 1.8 ppm/K. These SiC–diamond heat spreaders have been commercialized. Reaction bonded SiC ceramics combine the advantageous properties of high performance traditional ceramics, with the cost effectiveness of net shape processing. These materials provide high surface hardness, very high specific stiffness, high thermal conductivity, and very low CTE. Al-toughened SiC composite maintains many of the advantageous properties of reaction bonded SiC while providing higher toughness, higher thermal conductivity and more tailorable CTE. The composite is produced using reactive infiltration process, which allows near-net-shape components to be fabricated. CNTs have been successfully used to enhance toughness of reaction bonded SiC ceramics. Fracture toughness of reaction bonded SiC was increased from 4 to 7 MPa m1/2 (a 73% increase) using CNT reinforcement.

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