Present work highlights the progress in the field of polymeric package reliability engineering for a flexible thermoelectric generator realized by thin film semiconductor technology on Kapton®. Together with mechanical enhancement, the thermal insulation performance of the realized 3D custom package was tested. The effect of different plasma treatments on the mechanical performance and interface of a Polydimethylsiloxane (PDMS)/Kapton® assembly were investigated; in order to increase the package mechanical stability of the realized wearable power source, Kapton® surface wettability was investigated by static contact angle measurements using deionized water and PDMS as liquid test. In fact, well known weak adhesion between PDMS and Kapton® leads to delamination of the package with unrecoverable damage of the generator. Plasma effect on adhesion performances was evaluated by scratch test …