bluuebunny/crossref_metadata_2025_split huggingface dataset:
3D Net-Shape Manufacturing of Complex Ceramic Parts by High Resolution Stereo Lithography – Examples of Application to Biomedical and Industrial Products
Authors: Lafon Jean Baptitse , Chaput Christophe , Gaignon Richard , Delage Cyrille 
Published: October 2015

Solid Freeform Fabrication (SFF) processes are fairly new shaping methods, which allow the direct fabrication of complex ceramic structures, without tooling or machining, on the basis of a component CAD file. SFF techniques provide an attractive answer for applications with the need to produce custom designs while also controlling the product structure or producing multimaterial devices demanding improved properties or multifunctional components.
Stereolithography (SL) is a layer manufacturing process based on the space-resolved polymerisation of a UV photocurable compound consisting in a dispersion of ceramic particles in a monomer containing a photoinitiator. Improvements in the SL process, notably understanding and driving the key parameters influencing the 3D resolution of the reactive compound, now make it possible to directly manufacture useful 3D ceramic parts with final properties similar or identical to those obtained from traditional processes.
SL processing applications are numerous and include medical implants, complex microwave devices, refractory molds and cores, MEMS, microfluidic networks for micro reactors, drug delivery devices or biological analysis, etc...
Integration of Ni-Cu-Zn Ferrite in LTCC-Modules
Authors: Rabe Torsten , Naghib-zadeh Hamid , Glitzky Carsten , Töpfer Jörg 
Published: October 2015

Integration of magnetic functional components in LTCC circuit boards calls for co-firing of dielectric and ferrite tapes. Ni-Cu-Zn ferrites with permeability of μ =900 were developed which can be fully densified at the standard LTCC sintering temperature of 900 °C. Successful co-firing of this ferrite with dielectric tapes requires the adaptation of the shrinkage behavior of the materials as well as the thermal expansion during the cooling period - especially in the temperature range below the transformation point of the glassy phase of the dielectric tape. To match these preconditions, a new dielectric LTCC material with steep sintering curve and high thermal expansion coefficient was designed. Sintered multilayer composed of Ni-Cu-Zn ferrite and tailored dielectric tapes are free of cracks and possess no open porosity. No significant interdiffusion between the ferrite and dielectric tapes was found by EDX measurements. Compared to pure ferrite laminates the permeability of co-sintered Ni-Cu-Zn ferrite layers is drastically reduced to 400, i.e. a decrease of more than 50 %.
To investigate the origin of this permeability reduction, Ni-Cu-Zn ferrite laminates were sintered separately, and in combination with alumina release tapes or dielectric tapes, respectively. SEM and EDX analysis of co-fired laminates reveal differences in the ferrite grain growth behavior. Ferrite laminates with homogeneous microstructure and grain size up to 50 μm exhibit large permeability. However, growth of ferrite grains does not take place near the interface between ferrite and release or dielectric tapes. There is a strong correlation between high permeability and volume fraction of large ferrite grains. Regions of fine and coarse grains inside the ferrite layers show different bismuth concentration; the Bi-content is larger in regions of fine ferrite grains.
Laser Printing of RFID Antenna Coils on Ceramic
Authors: Büttner Dustin , Krüger Klaus , Zobrist Beat , Schönberger Andreas , Jung Dieter 
Published: October 2015

Printed electronics are a major field of activity in research and industrial applications nowadays, especially in thick-film technology. Within the last decade, large progress was made to digitally print electronic circuits, in order to supplement or replace the established screen printing technology. The advantage of digital printing is its capability to rapidly produce any layout desired at minimum space requirements. This highly flexible production method is especially applicable for prototyping and small series productions.
Electrophotography, commonly known as laser printing, has been considered very rarely as a method for digital printing of electronic circuits. It is a completely solvent-free method with high speeds and a high potential regarding precision. At Helmut Schmidt University, electrophotography is tried to be established as an alternative method to print silver lines as basis for a conductive layout.
After a first set of conductive silver lines was printed and the results were published, this paper describes the development from initial conductivity to a functional circuit element. Deficits in toner transfer to tape are examined and a more effective transfer method is established. Furthermore, the performance of the used silver toner is improved, and the best toner for the desired application is determined. Silver lines are printed on green tape and sintered in a co-firing process, as well as on ceramic using a post-firing process. After reaching a certain level of quality, a functional RFID antenna coil is printed that proves the capability of the process to create a conductive layout.
Crack Propagation and Detection in PZT-Multilayer Ceramics
Authors: Kühnlein Tobias , Poller Silvan , Rauscher Martin , Klonczynski Alexander 
Published: October 2015

Piezo multilayer ceramics are increasingly used under extreme condition such as high pressures in engine injection systems. The mechanical stability and reliability of the ceramic multilayer is of major importance for proper operation. Critical functional defects are caused by material fracture and flaw extension in the device. The flaw propagation in PZT-multilayer ceramics under mechanical load was examined using impedance spectroscopy and three-point-bending studies. Initial flaws were generated by applying a sinus ac-field on the specimens. The cracks were successively promoted and after the release of the external mechanical load the impedance spectroscopy was conducted. As a measure for flaw extension, the shift in the resonance frequencies and the sub-resonance height of the impedance spectroscopy was used. A functional dependence of the resonance frequency and the phase shift on the crack length was found.
The crack propagation was studied on flaws starting at the positive and negative electrode, respectively. The maximum fracture strength as well as the crack path depends on the electrode potentials. The variation in the fracture strength was caused by the different observed fracture mode: interface cracking, matrix-cracking and a combination of both. The morphology of the fracture faces was ascribed to an anisotropic behaviour, which is created by the sample processing, e.g. the poling process. A modified poling procedure with a lower poling temperature was analysed, which yielded a reduction of the anisotropy of the electrode strength. Impedance spectroscopy was found as a reliable measurement tool for automated flaw detection in PZT-multilayer ceramics.
Surface Micro Machined Actuators on Piezoelectric Bulk Material
Authors: Zaehringer Sandy , Widamnn Elisabeth , Schwesinger Norbert 
Published: October 2015

Using circular discs of piezoelectric material an easy adaptation to well-known silicon surface micro machining technologies is possible. Thus, several interdigitated electrodes layouts have been positioned on a planar lead-zirconate-titanate disc via lift off processes. Because of an inhomogeneous electric field distribution the actuated areas on the disc conduct a symmetric deformation of the bulk material without any need of a further passive membrane, as is necessary regarding common piezoelectric membrane actuators.
The most interesting deformation was shown by star shaped interdigitated electrodes. It was an overall downward movement (i.e. the side opposite the electrodes) of the actuated area and a center movement in the opposite direction about 25% of the downward movement. This phenomenon is further investigated, especially with regard to increasing the upward movement. Therefore, the behavior of the actuated area has been more thoroughly tested, using laser vibrometry, speckle imaging and white light interferometry. Based on the thus salvaged data, those actuators have been investigated especially concerning their deformation behavior in various clamping modes either during polarization and/or during actuation.
New Ferro L8 LTCC System Ready for High Reliability Electronic Packaging Applications
Authors: Henry Jim , Brown Orville , Graddy Ed , Stadnicar Ed , Gardner Bob 
Published: October 2015

Ferro glass and conductor core competencies have combined to develop a unique and superior electronic packaging system. Recent advances have resulted in a new mechanically robust packaging system for high frequency packaging applications. The new system is called L8 and is the result of Ferro glass technology combined with Ferro expertise in conductive pastes.
Packaging of complex, high reliability electronic devices require ceramic multilayer systems that can be co- fired with low loss conductors to form a hermetic environment. This is necessary as the device will be required to perform reliably in harsh environments for extended periods of time. Devices used in satellite, avionics and shipboard applications are just a few examples of applications where packaging of this type is a requirement.
L8 is based on a ceramic filled glass system with excellent low loss characteristics that have been measured up to 30 GHz. L8 has the further advantages of excellent tensile and flexural strength. The newly developed conductors and tape system provide a range of design options including the potential to significantly lower cost without sacrificing reliability for high volume manufacturing.
Our paper will introduce the L8 dielectric along with 4 conductor systems that comprise the L8 LTCC System. Studies on embedded and surface resistor pastes performance are also presented.
Measurement of nitrogen monoxide levels in gas flows with a micro total analytical system based on LTCC
Authors: Geiling Thomas , Welker Tilo , Bartsch Heike , Müller Jens 
Published: October 2015

The measurement of nitrogen monoxide (NO) concentration levels is a vital aspect of environmental analysis and the so called CHNS analysis. The chemiluminescent reaction with ozone in the gas phase is a well-established method for the measurement of atmospheric concentration levels in the range from 4 ppb up to 100 ppm.
In this contribution we present the design of a so called micro total analytical system (μTAS) for NO measurements designed in ceramic. Low temperature co-fired ceramics (LTCC) have proven to be the ideal technology, since they offer high chemical and thermal stability as well as high degree of freedom of design. The article gives an overview of the design process with emphasis on manufacture of the components and technological challenges regarding life-time.
Novel Technology Options for Multilayer-Based Ceramic Microsystems
Authors: Partsch Uwe , Goldberg Adrian , Ihle Martin , Hagen Gunter , Arndt D. 
Published: October 2015

Ceramic multilayer technologies as LTCC (Low Temperature Cofired Ceramics) or HTCC (High Temperature Cofired Ceramics) are applied for the fabrication of highly integrated ceramic microelectronic packages. Furthermore ceramic multilayer technologies offer the possibility of the additional integration of 3-D-structures for multilayer-based microsystems.
The paper presents a new machine for tape/ multilayer structuring combining micro punching tools and micro UV-laser ablation/ cutting. The application for the production of different multilayer based components is described (e.g. LTCC-based PEM fuel cell system, LTCC-based pressure sensors). Aerosol printing is a new technology e.g. for rapid prototyping for LTCC multilayer and 3-D-deposition of functional layers on LTCC. Advantages and limitations of the technology are discussed.
Fabrication of an Inductively Coupled Plasma Antenna in LTCC
Authors: Taff J. , Yates M. , Lee C. , Shawver S. , Browning J. , Plumlee D. 
Published: October 2015

With the size reduction of satellites, the need for miniaturized propulsion systems is increasing. This has led to research funding for the miniaturization of chemical and electric propulsion by NASA and the Air Force Office of Scientific Research (AFOSR). Miniaturized electric propulsion research has been an active area of interest recently. Electric propulsion systems are interesting candidates for miniaturization due to efficiency and the reduction in onboard propellant and the ability to apply existing techniques in electronic fabrication.
A miniature electrostatic thruster is being developed in LTCC at Boise State University. The thruster is composed of an antenna to create the plasma, a cylinder to contain the plasma and grids to extract the plasma beam at high velocity. In this work, the development of the inductively coupled plasma (ICP) antenna in LTCC will be presented. This antenna is fabricated using DuPont's 951 Low Temperature Co-fired Ceramic (LTCC). A Direct Write is used to apply silver paste for the spiral ICP antenna. Using LTCC allows for the antenna to be embedded in the device under a thin sheet of LTCC dielectric, which protects the antenna from ion back bombardment during operation. This thin sheet is the seventh layer of the total device, with the ICP antenna one layer below the top. The design of the antenna is based on the research done by J. Hopwood. This paper discusses the fabrication and performance of the ICP antennas in LTCC. These ICP antennas are operated at pressures from 10 mTorr to 1 Torr with radio frequencies (RF) of 500 MHz to 1 GHz to inductively couple with low pressure argon to produce plasma. The performance of the antennas will be verified with data showing the start and stop power of the plasma at various pressures and an electric field map of the RF field above the antenna.
Evaluation of Ceramic Substrates for High Power and High Temperature Applications
Authors: Kulkarni Srikanth , Arifeen Shams , Patterson Brian , Potirniche Gabriel , Elshabini Aicha , Barlow Fred 
Published: October 2015

Ceramic substrates with thin film and thick film conductor traces are widely used in microelectronic packages for high temperature operation. In high power applications where the maximum current in the package may be hundreds of amperes, much thicker conductive traces are normally required. For such applications, Direct Bonded Copper (DBC), Direct Bonded Aluminum (DBA) or Active Metal Bonded (AMB) substrates are good candidates. These substrates provide low electrical resistance and high ampacity, thereby enable the design of high power circuits for high temperature operation.
The most commonly observed failure mode in these substrates is the delamination of metal layer from the ceramic. The lifetime of a ceramic substrate can be significantly reduced by the processing conditions such as maximum process temperature, and the process gases that the substrates are exposed to. It has also been shown that the propagation of cracks in the ceramic can be abated by dimpling the metal layers along edges and corners.
In order to evaluate the effectiveness of these types of substrates for power applications, substrates with various combinations of metal thicknesses and ceramic composition (Al2O3 and AlN) were evaluated for delamination as a function of thermal shock cycles. These samples included both dimpled and non-dimpled metallization. The samples were thermally cycled between −40 °C and 200 °C. A few of these substrates were exposed to forming gas at 340 °C prior to thermal cycling to imitate process conditions. Sample randomization was performed to provide statistically significant data. After a certain number of thermal cycles, delamination cracks were observed to nucleate and propagate in the substrates. Data regarding the reliability of these substrates as a function of thermal shock cycles is presented in this paper, along with failure mechanisms that are commonly observed. Computer simulations were performed to understand the conditions that lead to delamination cracks, and to estimate the crack growth rates in these substrates.
Advanced 3D roughness analysis for the characterization of ceramic surfaces
Authors: Strass Karl-Heinz 
Published: October 2015

Advanced processes often hinge on the ability to reproduce specific surface characteristics. While throughout the past century, the mean roughness value, also expressed as Ra has often been used as the main parameter to classify a surface's ability to retain oil and provide a functional bearing surface, the materials, processes and required functionalities of modern surfaces go far beyond that application.
Superficial interfaces now often determine the ability of a consecutive layer to adhere to the substrate or, amongst others, enhance a surface's ability to exchange electrons or other elements. In many applications the surface itself enables the process the device is intended to deliver.
The paper discusses various approaches to measure surface roughness, and takes a closer look at more advanced surface roughness parameters that allow the user to more accurately and precisely determine a surface's ability to function within its desired boundary conditions.
We will review various technologies widely used to measure surface topographies, from the traditional stylus profilometry, to white light interferometry, confocal microscopy to optical systems that combine several of the advantages into one technology.
Almost none of the surfaces functions today are based on surface properties of a single line, hence the paper will review the correlation between single line scan metrology and real 3D metrology. Acquiring 3-dimensional data provides the user with significantly more information. Any directionality of surface properties can now be evaluated by taking advantage of more advanced and complex roughness parameters that indicate for instance, anisotropies of surface preparation processes.
Inkjetprinting of Multilayer Capacitors
Authors: Jeschke D. , Ahlfs E. , Krüger K. 
Published: October 2015

Capacitors are widely used passive components. Considering microhybrid circuits printed capacitors are desirable, however today's screen printing technology results in very low specific capacitance per area. Thus usually SMD components are preferred. In order to achieve a higher specific capacitance, simple plate capacitors are stacked to form multilayer components. The mask-less inkjet printing allows for realization of such structures. To keep the process simple, no in-between-sintering is applied; the entire component is co-fired in one final step.
For defining the geometry of the component, first general processability of the used material combination is examined. Among others it is determined, to which extend the structures can be decreased in size without affecting their functionality. In further experiments the effects of thermal expansion and sinter shrinkage are analysed.
To create multilayer capacitors, in a second step design is completed. Vias are embedded to bypass the dielectric layer respectively the opposing electrode. When increasing the height of the structure, the aspect ratio achievable by the printing process is considered.
LTCC 3D MICROMIXER OPTIMIZATION FOR PROCESS INTENSIFICATION
Authors: da Cunha Marcio Rodrigues , Seabra Antonio Carlos , Gongora-Rubio Mário R. 
Published: October 2015

Mixing of fluids is a very important unit operation for Chemical, Biochemical, & Pharmaceutical processes among others, with a great deal of interest for industrial and research sectors. Micromixers a new implementation in micro scale of mixers are being studied. Active (electrokinetic, pressure disturbances, ultrasonic, magneto-hydrodynamic) and passive (jet breakup, vortex, microchannels ) methods appear in the literature. In particular research of micromixers with microchannels having different kind of elbows are conducted focusing hydrodynamic phenomena in microscale, like caotic advection.
LTCC Microsystem Technology is suitable for the construction of micromixers because their inherent capacity of implementing 2D and 3D structures. The goal of the present work is to report our current study on LTCC micromixers based on microchannels having different kind of elbows for geometry optimization applying finite element Computational Fluid Dynamic numerical methods for process chemical intensification.
The study will contemplate nine different 2D and 3D LTCC micromixer geometries compared with straight channel micromixer and prospect hydrodynamic parameters as: flow rate, pressure difference, friction factor and head loss coefficient. It is also presented a description of flowage as a function of diffusion-convection equation in order to obtain the mixing performance of designed devices.
Steps towards a novel cost efficient low weight LTCC packaging technology for high-end RF applications
Authors: Bechtold Franz 
Published: October 2015

The emerging of a new GaN based generation of RF semiconductors provides new challenges to the packaging technology. RF performance, circuit functionality and power dissipation create new challenges to the packaging technology with respect to low losses, electrical stability, SiP integration, thermal management and reliability. Today LTCC provides a proven packaging solution for Standard GaAs devices. Increasing the frequency, power and functionality of the systems is the driving force to investigate novel packaging solutions. This paper describes the different steps how LTCC technology can cope with these requirements.
Based on a comparison between different available LTCC systems and a benchmark between DP 943 and DP 9k7, the packaging performance of the 9k7 system is in detail investigated. Technological features, relevant for RF performance, like cavities, conductor line resolution, via diameter and flatness are considered. Process capability, relevant for thermal management, SiP integration and hermeticity like brazing of heat sinks, integration of heat pipes, integrated capacitors and resistors are analyzed.
The impact of novel materials for heat sink and low cost materials for metallization and brazing will be evaluated with respect to weight and cost. The progress beyond the state of the art will be demonstrated by packaging solutions recently developed for RF applications.