High Density Interconnect Advantages

Alternative polymers that have certain advantages over polyimides have also been introduced they include poly(phenylquinoxaline), poly(phenylquinoline), and poly(benzocyclobutenes) (PBCBs) (93,116). The PBCBs have a low curing temperature (250 °C), low dielectric constant (2.6), low dissipation factor (0.0045), and low moisture absorption (0.3%) The development of specialty polymers for packaging and high-density interconnections will continue to be an active area of research as polymer manufacturers focus on the needs of the microelectronic industry. 

The major advantages of this technology include the ability to provide high-density interconnections with relatively short path lengths, which lead to higher-speed computers excellent thermal dissipation the ability to operate at elevated temperatures, excellent structural strength provision for a hermetically sealed transistor enclosure, excellent dimensional stability, and an overall low thermal coefficient of expansion. 

Meiko-BU. Meiko Circuits of Japan takes a photoresist and coats it onto a stainless steel panel. This starts the process to produce high density interconnect structures (HDIS) in a remarkable way. The advantages of this process is that surface geometries are not determined by etching or full additive metallization, the vias are under the surface lands, and the circuits are all flush with the dielectric, permitting the elimination of solder masks. On the negative side, this is a more expensive process that involves carriers. 

Functional prototype packages that demonstrate the feasibility and performance advantages of TFML interconnections have been described. These prototypes illustrate the broad range of applications of high-density TFML interconnections. 

Space and satellite applications are an excellent example of the proven high reliability, thermal performance, and thermal stability of ceramic interconnect teclmologies, in addition to tiie high density, functional integration advantages required for these applications. Figure 1.28 and Figure 1.29 are examples of thick-film and LTCC satellite circuitry. 

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