Embedded passives are becoming increasingly important for the manufacture of highly integrated electronic boards and packages. The need for embedded passives emerges from the growing consumer demand for product miniaturization thus requiring smaller components and space efficient packaging. This can be realized by replacing discrete components that demands a higher volume than embedded passives. Embedded passives have already been investigated in the last few years. However nowadays used dielectric materials have to be optimized in order to improve the performances of the passive components in terms of dielectric behaviour and reliability. The most promising candidates for dielectric materials applied for embedded passives are polymer-ceramic nanocomposites. In this paper the robustness of embedded capacitors using such commercial dielectrics regarding the environmental conditions (temperature and humidity) is studied. Microwave measurements performed on an embedded structure design for Low Noise Amplifier (LNA) MMIC decoupling allow to demonstrate clearly the capacity of this new technology.