Simulation and design of lossy transmission lines in a thin-film multichip package

A thin-film multichip package design was evaluated for its applications in packaging high-performance VLSI/ULSI chips. Typical thin-film interconnections (copper lines 8 mu m wide and 4 mu m thick) were analyzed, and a large CMOS driver was used in the simulation. It was found that a pitch of 32 mu m for the microstrip configuration and 20 mu m for the stripline configuration is required to obtain a low-crosstalk environment for an input frequency up to 1 GHz. It is shown that long lines (length between 8 cm and 18 cm) do not need any termination, but short lines (shorter than 8 cm, but longer than the length at which a line is considered to be a lumped circuit) must be terminated with customized termination resistors to obtain optimal package performance. The loading effects n the termination behavior of short and long thin-film microstrips are also discussed. It is shown that high power generation in thin-film lines at a high frequency (1 GHz) would require an advanced cooling technique for the thin-film multichip package.>