Entwicklung einer Dünnschichtglaspaste für Aluminiumoxidkeramik

A glass paste for alumina was developed to realized a fired thickness smaller than 2 my. The particle size of the glass powder was very small (d(59) equal 0,5 mym) and the thermal expansion coefficient was near to that of alumina

Thick Film Alloy Resistor System on AIN

Because of the high thermal conductivity AlN is of interest to substrate material for high power application. AgPd alloys can be used with "a non-reducible" glass for thick film resistors on AlN. These resistors are complex non-equilibrium systems. The paper describes correlations between the paste composition, the firing conditions, the phase content and the electrical properties of the fired films. The composition of the AgPd alloy and the PdO content mainly influence the TCR`s, the glass content the sheet resistance. With the investigated system it is possible to realize pastes with sheet resistance between 100 mOhm/sq and 1 Ohm/sq and with a cold- and hot-TCR in the range +/- 50 ppm/K for AlN

Water soluble paste systems

The aim is to substitute toxic and ecologically harmful leaning agents in the e lectronic industry (like Pregan Universal 4 or Kiwoclean), which are dangerous for the environment, form a lot of CO2 during the combustion and need a lot of energy for their production. Harmful solvents for the cleaning of screens and devices after screen-printing of electronic circuits can be substituted by water. In comparison to cleaning agents on organic base the application of water is more cost efficient and leads to more safety in use. Hence a development of water soluble paste systems is necessary. The new systems should have comparable properties to commercial available systems (not water soluble). Therefore different polymers and solvents for water soluble and ecological burn out organic vehicles were tested. The properties of the developed pastes were investigated and after characterisation of pastes the new water soluble organic vehicle was selected. The development comprised pastes for AlN (AgPd conductor paste, Ru O2 resistor pastes, encapsulating paste), pastes for LTCC (via-, innerlayer and conductor paste), pastes for SOFC (cathode, anode) and an Active Metal Brazing (AMB) Paste. It could be showed that water soluble pastes with equivalent characteristics to commercial pastes are producible. Cleaning as well as recycling can be made with water

Pressure detection with a resonance method

A new principle for pressure measurements is presented. It bases on the shifting of the resonance frequency of a diaphragm by mech. stress e.g. pressure. The diaphragm structure can be made easily by LTCC technol. A piezoelec. layer which is screen-printed works as sensor and actuator. The paper describes aspects of the material development, construction and characterization of the pressure sensor. Further on an electronic circuit for detection of the resonance frequency is presented

Technologieorientierte Optimierung von Pastensystemen fuer die Fertigung von 50 kW Leistungseinheiten der planaren SOFC (Siemens-Design) Abschlussbericht

The planar design concept of Siemens company for the high-temperature fuel cell (SOFC) enables the electrodes (cathode, anode) and the active and joining layers to be made by the screen printing process. So far, however, such layered paste systems prepared by this method could be tested and shown to be successful only in smaller stacks. The work reported and carried out in the period 1996 -1998 was intended to elaborate approaches for technology-level optimization of paste systems for application to thick-film system preparation as a low-price fabrication process for 50 kW stacks. The defined goals were to find ways for improving pastes and the thick-film preparation methods using the standard as well as enhanced powder materials, so as to improve the quality of fabricated stacks. Tasks involved encompassed determination of the relevant parameters with an effect on long-term stability and temperature resistance of the thick films, adjustment of the properties of pastes to advancements achieved in bipolar plate design, optimization of the paste systems for stack fabrication based on tests with suitable powders, suitable scale-up of paste preparation, enhancement of the reliability of the screen printing process in the preparation of structures up to a size of #>=#(20x20) cm"2. (orig./CB)In dem Planar-Konzept der Fa. Siemens fuer die Hochtemperatur-Brennstoffzelle (SOFC) koennen die Elektroden (Kathode, Anode), Funktions- und Fuegeschichten mittels Siebdruck realisiert werden. Ein solches vollstaendiges Pastensystem ist allerdings nur in kleineren Stacks erfolgreich getestet worden. Gegenstand der Arbeiten in der Phase 1996-98 ist die technologieorientierte Optimierung von Pastensystemen fuer den Einsatz der Dickschichttechnik als kostenguenstige Fertigung von 50 kW-Leistungseinheiten. Daraus ergeben sich folgende Ziele: - Pasten- bzw. Dickschichttechnologische Untersuchungen mit Standard- und weiter verbesserten Ausgangspulvern zur Qualitaetssicherung der Stackfertigung, wobei es insbesondere auf die Ermittlung von relevanten Einflussgroessen auf die Langzeitstabilitaet und Temperaturwechselbestaendigkeit der Dickschichten ankommt, - Anpassung der Eigenschaften von Funktionspasten an Weiterentwicklungen der bipolaren Platte, -Optimierung des Pastensystems fuer die Stackfertigung auf der Basis geeigneter Pulver, - Massstabsvergroesserung der Pastendarstellung, - Erhoehung der Zuverlaessigkeit des Siebdrucks fuer Druckstrukturen bis zu einer Groesse #>=#(20x20) cm"2. (orig.)SIGLEAvailable from TIB Hannover: F99B721 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Stapelbare Hochtemperaturbrennstoffzelle

DE 10342691 A UPAB: 20050506 NOVELTY - A stackable high-temperature fuel cell comprises an electrode unit with anode (3) at the fuel inlet and cathode (2) at the oxidant inlet with the cathode connected to an interconnection (5,8) by at least one sprung elastic contact. Pressure contacts (6) in the region of the cathode and interconnection are formed of electrically conductive ceramic. USE - As a stackable high-temperature fuel cell (claimed). ADVANTAGE - The contacts are chemically and mechanically stable at 800oC under oxidizing conditions and give a sufficiently high electrical conductivity