An IGBT finite element model aimed at facilitating the assessment of Fibre Bragg Grating sensing based direct on-chip temperature monitoring is first presented in this paper. A commercial off-the-shelf IGBT module geometry is characterised, and a thermo-electrical finite element model is then established using its features. The model is subsequently employed to evaluate the local thermal disturbances that may be introduced by the installation of the optical based temperature sensor directly on the top surface of the IGBT chip. The effects of the sensor thermal interface material characteristics, e.g., thermal conductivity and size, in the local temperature environment are investigated.