Materials compatibility issues in LTCC technology and their effects on structural and electrical properties

Although LTCC (low temperature co-fired ceramics) technology is an attractive solution for smart-packaging of micro-electronic devices, numerous studies are still underway to overcome the difficulties encountered during processing and application. These difficulties center on chemical and physical issues occurring between the LTCC components during firing. The chemical issues arise from the interaction of the glass phase(s) in the tape and the thick-films, whereas the physical issues are usually due to the shrinkage-mismatch of the tape and the screen-printed pastes. This is observed both microscopically and macroscopically in form of either chemical diffusion (by microscopy and spectroscopy analysis) or deformed structures (warpage, delamination, curling etc) respectively. The objective of this study is the basic understanding of the effects of processing conditions on the properties of the commercial thick-films those are screen-printed and fired with the LTCC tape. This will be analyzed by measuring the TCR (temperature coefficient of resistance) and sheet resistance values of PTC (positive temperature coefficient) resistors, which are prepared at different conditions. Moreover the results of a recent study, which aims to match the shrinkage behavior of the conductor pastes to that of the LTCC tape, are demonstrated.