Advanced packaging for GHz switching applications

We have developed a package technology platform based on solder flip chip on glass ceramic that satisfies high speed, high pin count, high power dissipation requirements for OC-48 and OC-192 switching and processing applications. We review the design features of a ceramic flip chip ball grid array (CBGA) package housing a large CMOS die with over 2000 bumps, and over 300 high bandwidth differential pair transmission lines. The package incorporates 50 Ω odd-mode impedance transmission lines to accommodate broadband data transmission at OC-48 data rates while providing great channel to channel isolation to reduce jitter. The package and IC are co-designed to allow very clean power supply delivery of several tens of amps of current while minimizing the impact of flip chip pad coupling to underlying analog and RF circuits. The package lid configuration is designed to provide good thermal performance while providing reliability margins for first and second level solder joint reliability. Actual device performance shows excellent eye-diagram at OC-48 data rate. Further electrical characterization shows even at OC-192 (10 Gbps) data rate, the package interconnect contributes less than 1 ps/mm rise time degradation and peak to peak jitter generation of 0.12 ps/mm. The combination of good attributes in terms of electrical performance, routing density, thermal performance and reliability makes this packaging platform superior to organic alternatives.