Integrated Passives in Ceramic Substrates
Passive integration is an effective technique to increase the component density. Passive elements may be integrated on the surface or embedded in a multilayer structure of the substrate. The combination of several integrated passives in one package to realize a certain filter response is called integrated passive device (IPD) or passive integrated device (PID). Capacitor dielectrics for ceramic circuits are available as tapes and pastes. The latter are used for plate capacitors on both the surface and within a multilayer structure. Traditional inductors in thick-film technology are made of printed conductor patterns on the prefired ceramic or low-temperature cofired ceramic (LTCC) tape. Integration of passives in LTCC is also used to build components. Several elements can be combined in a multilayer structure to achieve a specific electrical function. The designed LTCC components are arranged according to their interconnections. Symmetries in the schematic should also lead to symmetries in the placement to obtain equal conditions.