High frequency performance of GE high density interconnect modules

The layout and routing of high-frequency multichip modules (MCMs) require a detailed electromagnetic characterization of the interconnect structure in order to manage required design trade-offs intelligently. To provide this characterization for the GE high-density-interconnect (HDI) process, a number of test coupons containing a variety of transmission line structures were prepared. S-parameter data were measured using a vector network analyzer (VNA), and these measured data were compared to the theoretical predictions based upon classical transmission line theory. Reasonable agreement is obtained provided that skin and proximity effects in the lines and ground planes are taken into account and that the nonrectangular natures of the conductor cross sections are accurately modeled. Results suggest that insertion loss rather than crosstalk is likely to be limiting for frequencies up to 9 GHz. For 20% (2-dB) attenuation, line lengths are 3-12 cm for the frequency range of 1-9 GHz