Low insertion loss interposer approach for RF applications based on commercial LTCC tape, alkaline-free glass and printed metallization.

• Low loss interposer for RF applications is demonstrated. • Low temperature co-fired ceramics (LTCC) are cofired with alkaline-free glass. • Combination of cost-effective thick-film and precise thin-film processing. • Printable glass through vias (TGV) for heterogeneous system integration. • Stable shrinkage tolerances are achieved by the glass layer. Materials with high RF performance are in increasing demand due to the needs of modern telecommunications. Glass and low-temperature co-fired ceramics (LTCCs) are both interesting candidates for the design of complex signal transmission systems. Glass can be processed in large panels, and has suitable structure dimensions for silicon processing, but its multilayer capability is limited. LTCC is a mature technology for complex multilayer assemblies, but the structure dimensions and conductor line resolution are restricted by the need to use screen printing technology. The approach presented here combines the advantages of both technological domains: a thin glass sheet is bonded with no additional material to a LTCC multilayer ceramic and sintered to form a tight joint. Metallization of the glass is created using printable pastes and electroplating. Two fabrication routes are compared: etching of printed thick film metal layers, and semi-additive structuring. The results of RF measurements show a low attenuation per unit length for both types of metallization, indicating that our approach is a promising one for the integration of heterogeneous systems of RF transmission modules. [Display omitted] [ABSTRACT FROM AUTHOR]