Analysis of microscale heat transfer and ultrafast thermoelasticity in a multi-layered metal film with nonlinear thermal boundary resistance

The microscale heat transfer and ultrafast thermoelasticity in a multi-layered thin-film (MLTF) exposed to an ultra-short pulse laser is analyzed. In this article, the microscale heat transfer and ultrafast thermoelastic behaviors are examined by the parabolic two-step (PTS) model and the dynamical equations of thermoelasticity, respectively. The imperfect contact condition at the interface in a multi-layered thin-film is considered. Three nonlinear formulations are used to compute the thermal resistance at the interface in an MLTF. The thermal behaviors predicted by those nonlinear formulations at the interface are found to be significantly different. The laser intensity also plays an important role on the evaluation of thermal resistance for an imperfect contact situation. Excessive effective stress occurs at the interface due to the imperfect contact effect. Therefore, the interface of a multi-layered thin-film may be delaminated during the very early stage of the laser heating process, even though the thermal resistance is extremely small, from 1.2 × 10−8 to 1.35 × 10−8 m2 K/W.