Millimeter-Wave 3D Integration Techniques using LTCC and Related Multilayer Circuits

LTCC, HTCC, and similar sandwiched substrate structures provide the basis for high-density 3D integration and packaging of microwave and mm-wave circuits. Such multilayer substrates serve, at the same time, as carrier substrates for MIMICs and as a medium for high-density hybrid circuits which can be realized in a manifold of transmission line types in different substrate layers and combinations of these, coupled directly or via the electromagnetic field. This contribution will address a number of aspects of such substrates, especially for mm-wave applications, and it will provide two examples of realized circuit elements and components. One is a multilayer electromagnetically coupled feed-through structure into a package on top of the multilayer substrate, the other one a band pass filter in a mixed alumina - LTCC layer system to cope with the tolerance requirements of mm-wave filters in a standard production LTCC environment.