Untersuchung von mechanischer Schädigung an LTCC - Materialien

Research output: ThesisDiploma ThesisResearch

Abstract

Low Temperature Co-fired Ceramics (LTCCs) are dielectric (electrically insulating) glass-ceramic composites, which can also contain metallic structures. LTCCs are constituted by a glass matrix in which Al2O3 particles are embedded. LTCC composites are widely used in the electronics industry – e.g. as a ceramic-based substitute of polymer-based printed circuit boards (PCB). They are characterised – in comparison with polymer materials – by high thermal stability, stiffness and low thermal expansion coefficient. In these ceramic-based PCBs, both high conductive metallic materials as gold and silver and various passive components as capacitors, resistors and coils have to be integrated. The build-up of the LTCC sheets is multilayered, and is performed by lamination, printing with metal pastes followed by a sintering process. The sintering temperature can be kept low owing to the presence of the glassy phase. Thereby, common sintering of LTCCs with low-cost metals (e.g.: silver) at approximately 850°C is possible. From the sintered LTCC panels hundreds of elements can be produced by sawing or mechanical breaking; the elements are then end-tested by electric contacting with measuring tips. Although LTCC modules are electric elements, considerable mechanical stresses can arise during the manufacturing process and during operation. Therefore, failure of the component due to fracture is common. In this diploma work, the strengths of three different LTCC materials depending on various pre-damage modes were investigated. On the one hand, artificial defects in samples were generated by blunt and sharp indenters. On the other hand, cases were investigated where different existing edge-defects caused by cutting processes are present. The strength tests have been performed on plate- and barshaped specimens by using the ball on three balls test and the conventional bending test respectively. In principle in these samples lower strength with respect to the material strength was found. It became evident that each pre-damage mode affects the material in a different way, and it was concluded that the observed trends can be explained by microstructural differences.

Details

Translated title of the contributionInvestigation of mechanical damage in LTCC materials
Original languageGerman
QualificationDipl.-Ing.
Supervisors/Advisors
Award date13 Dec 2013
Publication statusPublished - 2013