DFM R&D stands for Design for Manufacturability, Research & Development. A little background to understand what DFM R&D is about: when you make products such as phones, iPads, etc. there are generally industry established manufacturing processes that are used to make each component that goes into the phone. These processes work, but have limitations that generally make progressing the level of technology that's shipped to the customers to be very difficult, due to those limitations. What a DFM R&D engineer at Apple does is to come up with crazy ideas to either 1) do the same process in a cheaper, stronger, or better way, or 2) create entirely different processes that can open doors that current ones can't, and then go on to validate the ideas to make sure it actually works and is feasible to implement on the scale of tens of millions of products a year.