This paper overviews the selected results of a two-year effort to develop design guidelines for IC, hybrid, and multichip packages, sponsored by Rome Laboratory at Griffiss Air Force Base.  The goal is to provide the designer with an approach to pro-actively incorporate reliability in the design process.  This approach, using physics of failure models, has the advantage of being useful for the design of MCM packages, using new materials, technologies, and architectures, which empirical field failure based methodologies cannot properly handle.  To illustrate the approach, an example of the design process for the die-attach assembly is presented.