40Gb/s Demonstration of IBM Standard Alumina BGA Packages

Abstract

For the proliferation of 40Gb/s high speed links to become a reality, highly cost-effective as well as innovative interconnect technology approaches must be available in a standardized product. One critical facet of the 40Gb/s OC-768 is the challenge of packaging the front-end chips that run at the serial link data communication rate. This paper describes the packaging of 40Gb/s MUX using unique, innovative and robust transmission structures and an improved BGA using IBM's mature alumina MLC material set. Critical performance data showing transmission eye diagrams for both a GPPO surface mount connectorized module and a through BGA module are included. The design of a-newly patented coplanar waveguide (CPW) structure that is embedded in standard IBM alumina package materials is described as an example of one through BGA solution. The combination of the high performance RF structures and enhanced BGA has shown that IBM standard alumina can be readily used at 40Gb/s to produce a very cost effective solution that can be produced with standard tooling while incorporating lead free compatible BGA with standard bond and assembly processes. The product also features new advanced thermal solution that incorporates direct substrate attachment and utilizes thermal conduction through the package in addition to the module lid. This extends the thermal performance of the inherently high thermal density chip in the module to accommodate the 70°C ambient thermal environment required by the OC-768 system specification.