**Preface to "Thermal and Electro-thermal System Simulation 2020"**

Microelectronics thermal experts from four continents came together in the fall of 2019 at the 25th THERMINIC Workshop at Lake Como in Italy, to discuss the latest issues in the design, characterization and simulation of the thermal and reliability problems in electronic devices and systems. The event, as usual, was sponsored by the IEEE Society, by the IEEE Components, Packaging, and Manufacturing Technology Society, and by numerous companies. The workshop is largely application-oriented and shows a rare balance of contributions from both academy and industry, often in great synergism. This issue had participants from 25 countries. The proceedings for the THERMINIC formal workshop are not usually published, but it is a tradition that the most valuable papers from the workshop appear in Special Issues or special sections in leading international journals. These journals are selected according to the nature and scope of the workshop in that particular year. At THERMINIC 2019, significant results were presented about thermal and electro-thermal simulations. For this reason, it was thought to organize a Special Issue of Energies entitled "Thermal and Electro-Thermal System Simulation". In this Special Issue, papers have been accepted whether they are derived from THERMINIC 2019 contributions or not. At the end of a very rigorous revision process, 14 papers are selected. Several papers, here proposed to the thermal community, have turned out to be extended versions of papers presented at THERMINIC 2019, thus confirming the fact that THERMINIC 2019 was a stage of choice for presenting outstanding contributions on thermal and electro-thermal simulation in electronic systems. The papers selected for this Special Issue testify in particular great activity in parametric thermal and electro-thermal modeling, multi-physics simulation of LEDs, electro-thermal simulation of power electronics applications. For the first time, the thermal modeling of batteries and modeling the thermal influenced motion of magnetic nanoparticles in micro-channels are also among the subjects featured. We hope that all the selected papers will provide useful information to the readers who are certainly interested in these recent important questions of microelectronics thermal issues.

#### **M´arta Rencz, Lorenzo Codecasa, Andras Poppe** *Editors*
