We describe the RDF-2020 release of the IEEE CEDA DATC Robust Design Flow (RDF). RDF-2020 extends the previous four years of DATC efforts to (i) preserve and integrate leading research codes, including from past academic contests, and (ii) provide a foundation and backplane for academic research in the RTL-to-GDS IC implementation arena. Implementation and analysis flows have been enhanced by the addition of steps including multi-bit flip-flop clustering, parasitic extraction and antenna checking, as well as a recent contest-winning global router. RDF-2020 also opens a new 'Calibrations' direction to support academic research on key analyses such as extraction and timing. An open-source physical design database with Tcl/Python/C++ APIs, a flow integration into a single scriptable application, and support for the newly-opened SKY130 manufacturable PDK, are also new this year. Our paper closes with a discussion of potential future directions for the RDF effort.