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We studied the sintering behavior and magnetic properties of Ni0.60‐yCuyZn0.42Fe1.98O3.99 ferrites. The shrinkage is shifted toward lower temperature with increasing Cu content y. The addition of Bi2O3 sintering aid induces enhanced shrinkage at T < 900°C and dense ceramics are obtained after sintering at 900°C. Such ferrites exhibit a permeability of µ = 135‐250 depending on the composition, sintering temperature and concentration of sintering additive. Ferrites with y = 0.20 show a high Curie temperature of Tc = 307°C. Multilayer inductors were fabricated and cofired at 900°C using ferrite tapes without and with 0.75 wt% Bi2O3. The compatibility of ferrite tapes with different metal pastes (Ag, AgPd, and Au) was evaluated. Ferrite tapes were also integrated between layers of low‐k dielectric CT708 tapes and successfully cofired at 900°C. Preliminary tests indicate that the multilayer inductors can be operated up to temperatures of 250°C. This demonstrates that high‐Tc Ni‐Cu‐Zn ferrites are promising magnetic materials for inductive components for high operating temperatures.

In a three-step development process CaCu3Ti4O12-based bulk ceramic pellets, tape-casted multilayer ceramic laminates, and multilayer ceramic capacitors with cofired electrodes were fabricated. The sintering behavior, microstructure, electrical resistivity, and dielectric properties were studied. At a firing temperature of 1050°C, an effective permittivity of about e' = 60 000 and 10 000 was observed for sintered pellets and multilayer laminates, respectively. The typical grain growth observed in pellets is suppressed in multilayer laminates. Impedance spectroscopy was employed to show that the bulk grain resistivity is similar in pellets and multilayer laminates, but the grain-boundary resistivity is higher in pellets. Tapes were processed into multilayer capacitors with Ag/Pd electrodes and cofired at 1050°C. All three types of samples, pellets, laminates, and capacitors were also processed with a glass additive, in which case they can be cofired at a lower temperature of 900°C. In glass-containing pellets, the temperature dependence of permittivity is weak and exhibits X7R characteristics for frequencies below ≈ 60 kHz. Our results demonstrate the high potential of CaCu3Ti4O12 for application in monolithic as well as in integrated multilayer capacitors.

Eine neue Systemintegrationstechnologie zur Kombination eines LTCC (Low Temperature Cofired Ceramic)-Foliensystems und eines nanostrukturierten Siliziumwafers zu einem Verbundsubstrat SiCer' wird vorgestellt. Die neuartige Systemintegration ermöglicht es, die Vorteile der Silizium- und Keramik-Technologie zu kombinieren. Die derzeitigen Konzepte zur Verbindung keramischer Substrate mit Siliziumwafern erfordern die Anwesenheit von Verbindungsmaterialien wie Glasfritten, Loten oder Klebstoffen. Alternativ kann über das anodische Bonden ein spezielles LTCC-Substrat, welches im thermischen Ausdehnungskoeffizienten an den des Siliziums angepasst ist, mit einem Siliziumwafer verbunden werden. Dieser Prozess erfordert eine kostenintensive Politur der Keramikoberfläche, welche durch die Verwendung der hier vorgestellten Verbindungstechnologie entfällt. Wahrend eines Standard-Laminationsprozesses wird der bereits vorstrukturierte Siliziumwafer oder Einzelkomponenten desselben ohne Hilfsstoffe mit einem keramischen Träger vor dem Sintern verbunden. Schwarzes Silizium (auch bekannt als Black Silicon', eine durch Selbstmaskierung im Plasmaätzprozess entstehende nanoskalige Funktionalisierung der Si-Oberflache) wird mit einer keramischen Grünfolie verpresst und anschließend druckgesintert. Der dabei entstehende Werkstoffverbund mit nanoskaligem Interface führt zu einer extrem belastbaren Verbindung, die die Festigkeit einer Bondverbindung bei weitem übersteigt. A smart concept for micro-nano-integration based on a new bonding technique between nano-scaled, modified BSi (Black Silicon) and an adapted, unfired LTCC (Low Temperature Cofired Ceramic) substrate (BGK) is presented. The novel technique combines advantages of silicon and ceramic technology. Current bonding concepts of silicon on ceramics need joining materials like solders, adhesives or glass frits. Alternatively, silicon components can be mounted to a TCE-matched (thermal coefficient of expansion) and fired LTCC substrate using anodic bonding, which requires expensive surface preparation such as polishing. This step is eliminated by the use of the new technique. During a standard lamination process a self-organized, nanostructured, grass-like silicon surface is joined with the green ceramic tape. Pressure assisted sintering allows the cofiring of the laminate. Dense contact between the Black Silicon surface and the ceramic is achieved by optimization of the nano-interface and the lamination procedure. Hermeticity and gas-tightness of the interface are given.