A model system for the optimization of lamination parameters of PTFE-based dielectrics and metal surfaces

In microelectronic packaging, organic dielectric materials continue to displace ceramic materials because of cost, reduced weight, and performance advantages. Because thermosetting dielectric composites have long found widespread use in printed wiring board (PWB) fabrication, they have been the components of choice for many organic chip carriers. Conversely, thermoplastic dielectrics, such as fluoropolymer (FP), and in particular poly(tetrafluoroethylene)- based dielectric composites (PTFE composites) have seldom found use in multilayer wiring packages in spite of their attractive electrical properties due to their processing challenges. In this paper, we report the use of a model system comprising pure PTFE film and Cr-coated copper surfaces to optimize the bonding process through lamination conditions for a fluoropolymer composite and chromium-coated copper surfaces and to study both the interface mechanics and its chemistry as a function of processing parameters. The significant finding of the investigation was the linkage between the macroscopic mechanical properties of the interface and the observable chemical alteration of the same under some lamination conditions. The relationship of the interface properties and the processing conditions extend a conceptual framework for the thermodynamics of the metal-polymer interface and the reliability of these electronic packages in their practical designs.