Packing tape casting

Concerning microfiltration, in which pores of less than 1 pm are needed (typically 0.1-1 pm), suspensions of submicrometer powders must be processed using slip-casting or tape-casting techniques, depending on the support shape (flat or tubular). Smaller pore sizes are required for ultrafiltration. In this case pores result from the packing of colloidal particles, which cannot... 

Various additives, generally with very low concentrations, have been used to control the characteristics of the feed materials, in order to achieve desired shapes and control the packing uniformity of the green body of ceramics. For some methods, such as tape casting and injection molding, the use of suitable additives is especially important. The additives can be either organic or inorganic materials. 

The colloidal techniques described in Chapter 4 provide considerable benefits for the control of the packing uniformity of the green body. The production of green bodies with uniform microstructure from a fully stabilized colloidal suspension of spherical, fine, monodisperse particles has not been incorporated into industrial applications where mass production is desired and fabrication cost is a serious consideration. Colloidal techniques, however, play an important role in the low-cost forming methods of slip casting and tape casting, as well as in the less commonly used methods of eletrophoretic deposition and gel casting. 

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. ... 

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