High Frequency Performance of GE High Density Interconnect Modules

Layout and routing of high frequency multichip modules (MCM’s) requires a detailed electromagnetic characterization of the interconnect structure in order to intelligently manage required design trade-offs. To provide this characterization for the GE high density interconnect process (HDI) 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: 1) skin and proximity effects in the lines and ground planes are taken into account, and 2) 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 range 3–12 cm for the frequency range 1-9 GHz.