Qualification procedure for moisture in embedded capacitors

Embedding passives in PCB permits to gain in integration density while enhancing electromagnetic compatibility performances. The choice of the dielectric film is fundamental for large frequency band stability of embedded capacitances. However, these materials are prone to water absorption, which can lead to functional parameter degradations and additional stresses at the interfaces. This paper presents experimental capacitors embedded in FR-4, and finite element simulations of moisture absorption in various dielectric materials. Technological choices, as well as the qualification procedure, can be improved thanks to the simulation results.