Casting chip substrate

FIGURE 2.14 Electron micrograph of a turn in the channel fabricated in a PDMS chip, created by casting the polymer against a positive relief, which is made of photoresist patterned on a glass substrate. The roughness in the side wall arises from the limited resolution of the transparency used as a photomask in photolithography [1033]. Reprinted with permission from the American Chemical Society. 

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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