Publications de Thomas Maeder | EPFL Graph Search

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Packaging is the last step of the manufacturing process of Microsystems. The LPM is working on the development of a two-part soldered packaging. One part of the package is metallic; the other part is made of glass. The goal of the project is to solder the ...

Thick-film materials are very advantageous for piezoresistive pressure and force sensors because of ease of processing, reliability and low cost. The standard substrate material used with thick-film technology for sensing is alumina, but its elastic modulus is high and its strength rather low. Steels offer better mechanical properties and permit assembly without an elastomer seal, which is required for pressure sensing in severe conditions. In order to use the steel as substrate, the standard firing tempera

Performance of piezoresistive thick-film pressure sensors on steel substrates is hindered by the high required firing temperatures of the layers, which cause degradation of the substrate mechanical properties. Special steels or alloys that are relatively unaffected by these temperatures are available, but their cost is very high. A much more promising alternative is the reduction of the thick-film firing temperature, in order to allow application of the standard high-strength steels used in thin-film cells.

In this work, we study the long-term mechanical strength under static load - i.e. static fatigue performance or resistance to subcritical crack growth - of ceramic thick-film circuits, namely how the static fatigue of the substrate is affected by the prese ...

Smart packaging concept has been the driving force for the search of advanced technologies to produce multi-functional micro-scale devices for long years. In this sense, LTCC technology has been recently addressed as the suitable choice for a wide range of applications. In addition to its attractive characteristics for high-frequency applications those have been profited for a long time, it receives a growing attention for sensor applications in the recent years as well. This is due to the easy machinabilit

Micro-scale solid oxide fuel cell is a promising power generation technology for portable devices such as laptop, medical devices and personal electronics. One of the key goals in design of μ-SOFC systems is to use common hydrocarbon fuels such as propane/butane, which requires an additional micro-scale gas-processing unit (GPU) to reform the fuel, avoiding the coking on the μ-SOFC membranes. However, no integrated micro-fabricated testing platform has been reported for evaluating the stability, thermal man

This work describes the fabrication and test of a high temperature (+200°C) capable high frequency transformer. It was manufactured using Low Temperature Co-fired Ceramic (LTCC) technology, which allowed the complex multilayer structure of ceramic and meta ...

This paper presents the development of radial eddy-current position sensors for high temperature active magnetic bearing (AMB) applications. Thick-film technology was used to realize silver coils printed on ceramic substrates. Long term measurements showed ...

Recent developments in thick-film technology have seen the widespread introduction of lead- free alternative to traditional conductive, dielectric and overglaze compositions. Resistors, however, have lagged behind this trend, as developing balanced and well-behaved resistive compositions from scratch is significantly more involved than other thick-film materials. Bismuth- containing glasses based on the bismuth-zinc-boron-silicon oxide system, which have been studied for over 20 years, constitute a promisin

An innovative multifunctional LTCC module has been designed for miniature atomic clock packaging. The components of miniature atomic clocks need to be efficiently packaged and connected to each other, and a precise temperature control is required for them. ...

Several bottom electrode systems for ferroelectric thin film deposition onto reactive substrates or reactive metal films have been investigated with respect to chemical barrier properties and contact resistivity. Such electrode systems should not deteriorate by oxidation, and should prevent oxygen diffusion into the underlying base metal. First, the protective performance of Pt, Ru, RuO2/Ru, and Cr has been evaluated on reactive substances such as W, Zr, Mo, and TiN; On most materials, a reactive and passiv

Recently, high-strength zirconia-toughened alumina (ZTA) ceramic substrates have attracted interest, because they offer much improved mechanical properties over straight alumina, while maintaining advantages such as good thermal conductivity and chemical stability. This allows their application in high-power electronics and piezoresistive thick-film sensors, where the substrate is subjected to considerable stress. This work examines the impact of processing a range of thick film materials (Ag- and Au-based

In this work, we investigate a new method of low-pressure lamination of low-temperature cofired ceramic (LTCC) tapes, by pre-coating with specially-formulated adhesive layers. This allows fabrication of intricate structures that would be destroyed by high lamination pressures, yet preserves compatibility with standard processing operations, such as blanking, laser cutting, punching, via filling and screen printing. Techniques proposed previously are application of adhesive tapes, solvents or glues. These me

Speciation analyses of an element allow obtaining information on the concentrations of its chemical forms present in specific environments. Chromium is largely distributed in industrial effluents often at acid pH, with the relevant oxidation states Cr (III) and Cr (VI) having contrasting impacts on the environment and health. While trivalent chromium is relatively harmelss and is an essential trace element, the hexavalent form is highly toxic. Therefore, it is important to know which species is stable, and

In this work, a set of low-temperature thick-film dielectrics consisting of two high-lead low-temperature glasses, stabilised by various amounts of alumina filler, is characterised on alumina and aluminium metal, as a function of firing temperature. Corres ...

Although inorganic thick-film materials are usually very stable, load sensors (i.e. force, torque and pressure) based on the piezoresistive effect of thick-film resistors often exhibit some drift, with major contributions stemming from a) temperature changes or gradients, coupled with the temperature coefficient of resistance (TCR) of the sensing bridge resistors, and b) ill- defined mechanical boundary conditions, due to insufficient decoupling, plastic deformation used materials, friction or loading error

Force and pressure sensing technology applied to smart surgical instruments as well as implants allow to give a direct feedback of loads to the surgeon lead to better reliability and success of surgical operations. A common technology used for sensors is l ...

Microstructured reactors (MSR) with characteristic dimensions below 100 μm are warranted to maintain close to isothermal conditions when carrying out quasi-instantaneous highly exothermic reactions. Unfortunately, such small dimensions increase the risk of clogging, create high pressure drop and are costly to number-up. The multi-injection (MI) MSR, where one of the reactants is added stepwise along the reactor length, allows working with larger dimensions (diameter >500 μm) while maintaining good temperatu

Mechanical and electrical connecting of piezoelectric actuator is often done using conductive glue. Its advantage is not to heat the piezoelectric actuator during connection. But there are many disadvantages to gluing; the main one is curing time. Welding is another alternative, but when done in an oven, the temperature needed for this operation might destroy the heat sensitive actuator. The method described in this paper is laser soldering of piezoelectric actuator. The piezo actuator is mechanically and e

A vast class of disordered conducting-insulating compounds close to the percolation threshold is characterized by nonuniversal values of transport critical exponents. The lack of universality implies that critical indexes may depend on material properties ...

Thomas Maeder

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Laser soldered packaging hermeticity measurement using metallic conductor resistance

Piezoresistive properties of low-firing temperature thick-films on steel sensors

High performance low-firing temperature thick-film pressure sensors on steel

Long-term mechanical reliability of ceramic thick-film circuits and mechanical sensors under static load

Structuration of micro-fluidic devices based on low temperature co-fired ceramic (LTCC) technology

Design, Fabrication and Characterization of a Gas Processing Unit Testing Platform for Micro-Solid Oxide Fuel Cells

Fabrication and Test of High-Temperature Ceramic Transformer

Thick-Film Radial Position Sensor for High Temperature Active Magnetic Bearings

Lead-free low-firing thick-film resistors based on bismuth glasses and ruthenium oxide

Effects of Thermal Losses on the Heating of a Multifunctional LTCC Module for Atomic Clock Packaging

Conducting barriers for direct contact of PZT thin films on reactive substrates

Long-Term Mechanical Reliability of Ceramic Thick-Film Circuits and Mechanical Sensors Under Static Load

Lamination of LTCC at low pressure and moderate temperature using screen-printed adhesives

Diseño de plataformas de estado sólido para la determinación simultánea de cromo III y VI [Design of solid-state platforms for the simultaneous determination of Cr III and VI]

Low-temperature thick-film dielectrics and resistors for metal substrates

Thick-film Load-sensing bridges – Effect of Temperature and Mechanical Boundary Conditions

Load sensing surgical instruments

Intensification of highly exothermic fast reaction by multi-injection microstructured reactor

Laser soldering of piezoelectric actuator with minimal thermal impact

Study of electrical properties of piezoresistive pastes and determination of the electrical transport