Estimation of thermal constriction resistance for simple thermal network analysis of electronic components

Related to the thermal contact resistance, lots of studies have been done on the thermal constriction resistance, which is a measure of the additional temperature drop at the contact interface [1]. And almost all of those studies have been conducted based on the two-dimensional cylindrical coordinates system. In the same way, the additional thermal resistance associated with the geometrical constriction is often encountered in the electronic components like relay circuits, the printed circuit boards, and so on. In these cases, however, heat is frequently transferred through a thin and narrow passage, which should be treated by two-dimensional rectangular coordinates system.