Aluminum Nitride Ceramics

It is generally accepted that lattice oxygen - that is, impurity oxygen dissolved in the AlN lattice - is the dominant factor lowering the thermal conductivity of AlN ceramics, as described below. It was proposed by Slack that the incorporation of oxygen in AlN occurs by the dissolution of AI2O3, via the following plausible 

Fabrication method Phase composition (%) a p Oxygen content (mass%) 

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Yoshimura HN, Molisani AL, Narita NE, Cesar PF, Goldenstein H. Porosity dependence of elastic constants in aluminum nitride ceramics. Materials Research 2007 10(2) 127-133. 

Laurenko, V. A. and Alexeev, A. F., Oxidation of Sintered Aluminum Nitride, Ceramic International [9] 80... 

ELID Grinding Characteristics and Surface Modifying Effects of Aluminum Nitride Ceramics... 

I 9 AIN Ceramics from Nanosized Plasma Processed Powder, its Properties and Application Table 9.1 Characteristics of aluminum nitride ceramics. 

Figure 70. Sintered aluminum nitride ceramic, (a) DIC. By finishing with a relief pohshing step using colloidal SiOj, the grain structure is made visible. The white components consist of iron and silicon, (b) BF. Grain boundary etching by a chemical method. The phases consisting of iron and silicon have been dissolved away.

Table 53. Recommended preparation of a copper coating on an aluminum nitride ceramic...

The experimental techniques described above to analyze ceramic—metal interfaces will now be illustrated using an example of brazing AIN. Comparatively little work has been reported on brazing aluminum nitride ceramics. Since a primary application for aluminum nitride is as a substrate for electronic applications, the focus has been on low-temperature brazing, using a variety of commercially available alloys based on the copper—silver—titanium system. 

Barrett Jackson, T., Virkar, A.V., More, K.L., Dinwiddie, R.B., and Cutler, R.A., High-thermal-conductivity aluminum nitride ceramics the effect of thermodynamic, kinetic, and microstructural factors, / Am Ceram Soc 80(6) 1421-1435, 1997. 

Watari, K., Ishizaki, K and Fujikawa, T. (1992b) Thermal conduction mechanism of aluminum nitride ceramics. J. Mater. Sci., 27, 2627-2630. 

Substrates made by the multilayer process from tape cast alumina have received considerable attention in recent years for multichip module (MCM) applications. An MCM consists of an array of closely packed chips on an interconnect board several inches on a side. Cofired ceramic is attractive relative to organic laminates because its thermal conductivity is almost 2 orders of magnitude higher, an important consideration in high-density circuitry. In addition both alumina and aluminum nitride ceramics are more closely matched to silicon in CTE than are organic boards. For similar reasons, alumina and AIN are attractive for ball grid array (EGA) mounting of chips. ... 

L Pauling. The Nature of Chemical Bond. Ithaca, NY Cornell University Press, pp. 64-107 (1960). N Kuramoto, H Taniguchi, I Aso. Development of translucent aluminum nitride ceramics. Am Ceram Soc Bull 68 883 (1989). 

S Hagege, Y Ishida, S Tanaka. TEM analysis of impurity induced microstructures in sintered aluminum nitride ceramics. J Ceram Soc Jpn Int Edn 96 1093 (1988). 

F Miyashiro, N Iwase, A Tsuge, F Ueno, M Nakahashi, T Takahashi. High thermal conductivity aluminum nitride ceramic substrates and packages. IEEE Trans Components, Hybrids, Manuf Tech-nol 13(2) 313-319 (1990). 

H Sumino, F Ueno. Diffusion of elements in AIN ceramics. Proceedings of the International Symposium on Aluminum Nitride Ceramics, Tokyo, 1998. 

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