bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and fabrication of gas tight optical windows in LTCC
Authors: Welker T. , Geiling T. , Bartsch H. , Müller J.
Published: October 2015

Beside the possibilities low temperature co-fired ceramics (LTCC) offer for electric devices they also enable the fabrication of micro fluidic elements like channels and embedded cavities. Hence, LTCC facilitate the realization of complex and integrated micro fluidic systems. Examples can be applied in many areas like micro fuel cells and reaction chambers for synthesis of chemical compounds.

However, for many applications it is necessary to have an optically transparent interface to the surroundings. The integration of optical windows in LTCC opens up a wide field of new and innovative applications such as the observation of chemiluminescent reactions. These chemical reactions emit electromagnetic radiation and thus offer a method for noninvasive detection.

The optical windows consist of thin glasses (≤ 500 μm) bonded by thermocompression onto a LTCC substrate. As the bonding agent, a low temperature sealing glass paste was used. Borosilicate glasses and fused silica as well as silicon were successfully bonded onto LTCC. In order to bond materials with a large CTE mismatch (i.e. fused silica) to LTCC, it is necessary to limit the heat input to the bond interface. Therefore, a heater structure was integrated into the LTCC substrate beneath the bond interface. This bonding process provides a vacuum proof and gas tight optical port (< 5 × 10−10 mbar·l/sec) with a high bond strength.
Determination of damage zone in fatigued lead zirconate titanate ceramics by complex impedance analysis
Authors: Zhang Yong , Wen Baohua , Ma Liang , Liu Xiaolin
Published: October 2015

The electric properties of the modified lead zirconnate titanate ceramics with different fatigue cycles were studied over a temperature range of 300 to 550 °C. Combination of impedance and conductivity plots was utilized to understand the contributions arising from different regions in the PZT ceramics, i.e. the grain boundary and ceramic-electrode interface region. The results showed that both the dc conductivity of the ceramic-electrode interface and the dc conductivity of the grain boundary decrease with increasing cycle number. And the dc conductivity of the ceramic-electrode interface decreases larger during the fatigue process. Based on these results, we deduce that the damage zones underneath the electrodes are the main source of fatigue in ceramics.
Cofiring behavior of multilayer inductors based on substituted Y- and M-type hexagonal ferrites
Authors: Bierlich S. , T[ouml]pfer J. , Barth S. , Pawlowski B. , M[uuml]ller J. , Bartsch-Torres H.
Published: October 2015

Sinter-active soft ferrites with adequate permeability profiles are required for the fabrication of multilayer ferrite inductors (MLFI). For MLFI fabrication, a Low Temperature Ceramic Co-firing (LTCC) process is used. Substituted hexagonal ferrites of Y-, and M-type represent an important family of soft ferrites which might operate at high-frequency conditions up to 2 GHz. However, for Ag-based multilayer inductor applications a sinter process at 900°C is required. Low-temperature sinter-ability is provided by the use of sub-micron powders and/or sintering additives.

Substituted Y-type hexagonal ferrites Ba2Co2-x-yZnxCuyFe12O22 were obtained after sintering at 1000°C. Substitution of Cu for Co improved the low-temperature sintering behavior. The addition of 5wt.% Bi2O3 guarantees almost complete densification at 900°C. The saturation magnetization and permeability are significantly affected by the Zn-concentration. A maximum permeability of μ′ = 10 and cut-off frequency fg~2GHz was observed for a ferrite with y = 0.4.

Co/Ti-substituted M-type BaFe12-2yCoyTiyO19 ferrites can also be used for multilayer inductors. The magneto-crystalline anisotropy changes from uniaxial to planar upon Co/Ti-substitution, and ferrites with y≥1.1 exhibit soft magnetic behavior. Ferrite powders were prepared at 1000°C. The addition of a sintering aid shifts the temperature of maximum shrinkage down to below 900°C and dense samples were obtained after firing at 900°C. A permeability of μ′ = 16 and a resonance frequency of 1 GHz was observed. Substituted M-type ferrites are stable during co-firing at 900°C and show no sign of decomposition, i.e. these materials are LTCC-compatible.

Ferrite tapes were prepared by tape casting and multilayer structures were fabricated by screen printing, stacking, lamination and final co-firing. Firing was performed at LTCC conditions i.e. 900°C. We report on the co-firing behavior, microstructure and permeability of monolithic laminates. It is shown, that hexagonal Co2/Zn2Y- and Co/Ti-M-type ferrites are excellent magnetic materials for multilayer inductors.
Low firing functional materials for application in power electronics
Authors: Barth St. , Kastner F. , Rößler M. , Wentorp R. , Töpfer J. , Bartnitzek Th.
Published: October 2015

In the past significant effort has been obtained on the miniaturization of electronic devices, for example in the field of cellular phones or other portables devices. Mainspring of this process is the huge success that has been obtained with giant integration densities on chip level. In contrast passive components are actually the most important bottlenecks in the upcoming miniaturization process, first of all for applications in power electronics. Especially in the field of electric mobility and innovative lighting technologies an increasing demand arises for miniaturized transformers and converters. Miniaturization of power electronic devices concentrates however the dissipation heat in a smaller volume, leading in most cases to higher operation temperatures. LTCC (Low-Temperature-Cofiring-Ceramic) as a ceramic multilayer interconnection technology has been employed for the development of 3D-high integrated electronic modules, marked by an excellent thermal robustness. Actual integration of inductors or capacitors in LTCC-boards is restricted to SMD's, limiting further miniaturization in an important manner. Hence the monolithic integration of inductors and capacitors into ceramic multilayer circuit boards is a straightforward approach to gain higher integration levels in power electronics.

We report on the preparation and processing of low sintering materials for the implementation of ferrite cores into LTCC multilayer boards. Different semi-finished products based on ferrite powders have been elaborated. Sintering behavior of these materials has been studied and material compatibility with different standard LTCC materials was tested.
A shielded and robust LTCC BGA-interconnect for Ka-band satellite flight hardware
Authors: Klein Tobias , Günner Carsten , Kulke Reinhard
Published: October 2015

The complexity of today's satellite systems is ever-growing and system weight and size of the subcomponents are becoming even more critical as the number of channels increases. A possible solution for achieving small systems, while maintaining reliability, is the use of the LTCC process. The so-called Keramis technology is a modular concept, where a number of small, hermetically sealed LTCC modules are connected on a carrier substrate. For these systems, the interconnect technology that connects the different LTCCs is of high importance. This paper presents a novel BGA interconnect for high frequency operation up to 40 GHz.
SiCer - A substrate to combine ceramic and silicon based micro systems
Authors: Fischer M. , Mache T. , Pawlowski B. , Schabbel D. , Müller J.
Published: October 2015

A silicon-on-ceramic (SiCer) wafer-shaped substrate, allowing a simultaneous fabrication of ceramic and silicon based microsystems is presented. The substrate, based on the recently introduced 'silicon-on-ceramic integration concept', can be processed by standard MEMS and LTCC technologies. The monolithic compound is fabricated by using lamination and pressure assisted firing of a nano patterned silicon wafer with a low temperature cofired ceramic tape (LTCC). The LTCC is adapted to silicon (TCE and morphology). LTCC functionalities such as electrical and thermal vias, passives, fluidic channels, etc.,. can be pre-processed in grid dimensions or individually. Through Silicon Vias (TSV) in the silicon layer can be combined with the vias in the LTCC. The silicon layer can be fabricated as thin as necessary for the desired functionality, whereas the insulating LTCC layer ensures the mechanical stability of the SiCer wafer. In addition, the LTCC layer includes electrical functionalities like signal routing and passive integration. Using SiCer substrates, the bigger part of back-end processes for silicon microsystems such as assembly and the crucial part of packaging, can take place before any micro structuring is generated. Thus, the influence of these processes to the sensitive micro structures can be minimized. The SiCer substrate is fundamentally temperature-stable up to 1000 °C. The fabrication steps of the SiCer substrate, particularly several options for TSV's are explained. Material characteristics and new technological approaches with the SiCer substrate are presented.
LTCC Substrates for High Performance Strain Gauges
Authors: Brandt Bjoern , Gemeinert Marion , Koppert Ralf , Bolte Jochen , Rabe Torsten
Published: October 2015

Recent advances in the development of high gauge factor thin-films for strain gauges prompt the research on advanced substrate materials. A glass ceramic composite has been developed in consideration of a high coefficient of thermal expansion and a low modulus of elasticity for the application as support material for thin-film sensors. Constantan foil strain gauges were fabricated from this material by tape casting, pressure-assisted sintering and subsequent lamination of the metal foil on the planar ceramic substrates. The sensors were mounted on a strain gauge beam arrangement and load curves and creep behavior were evaluated. The accuracy of the assembled load cells correspond to accuracy class C6. That qualifies the load cells for the use in automatic packaging units and confirms the applicability of the LTCC substrates for fabrication of accurate strain gauges. To facilitate the deposition of thin film sensor structures onto the LTCC substrates, the pressure-assisted sintering technology has been refined. By the use of smooth setters instead of release tapes substrates with minimal surface roughness were fabricated. Metallic thin films deposited on these substrates exhibit low surface resistances comparable to thin films on commercial alumina thin-film substrates. The presented advances in material design and manufacturing technology are important to promote the development of high performance thin-film strain gauges.
Novel glass free ceramic for LTCC applications
Authors: Abhilash Dhanesh Thomas P. , Sebastian M. T.
Published: October 2015

The LiZnPO4 ceramic has been prepared by the conventional solid state ceramic route. The ceramic sintered at 825 °C has an εr of 4.9, Qu×f of 65400 GHz, and τf of −80 ppm/°C. The LiZnPO4 ceramic shows low coefficient of thermal expansion (CTE) of 5.3 ppm/°C. The slightly large negative τf of LiZnPO4 has been tuned nearly to zero with TiO2 addition. LiZnPO4-TiO2 composite containing 0.15 volume fraction TiO2 sintered at 925 °C shows good microwave dielectric properties: εr = 7.8, Qu×f = 39800 GHz and τf = −6.8 ppm/°C. LiZnPO4−0.15 Vf TiO2 composite shows a CTE of 6.9 ppm/°C.
Gas Permeation Measurements on Low Temperature Cofired Ceramics
Authors: Goeke R.S. , Grubbs R.K. , Yazzie D. , Casias A.L. , Peterson K.A.
Published: October 2015

Commercial low temperature cofired ceramic (LTCC) technology is established in microelectronics and microsystems packaging, multichip and radio frequency (RF) modules, and sensors. The ability to combine structural considerations with embedded traces and components using laminated glass-ceramic tapes has created solutions to unconventional packaging requirements of micro-electro-mechanical systems (MEMS) devices. Many MEMS devices such as resonators are very sensitive to pressure and require packaging in a vacuum environment. Attaining and maintaining desirable pressure levels in sealed vacuum packages requires knowledge of the permeation characteristics of the vacuum envelope and the sealing materials.

An experimental system to measure the time dependent gas permeation through LTCC at temperatures from room temperature to 500°C has been developed. This system utilizes a membrane technique in which a gas is allowed to permeate through a test sample, held at a constant temperature, into a high vacuum chamber where it is detected using mass spectrometry. The gas permeation value is determined from the steady state gas flux through the sample. The gas diffusivity and solubility in the material were calculated using data from the time dependent approach to the steady state condition. The gas-solid permeation data for helium through DuPont 951 LTCC is presented and compared to the permeation through other common vacuum envelope materials such as glasses and high-purity alumina ceramics. Application of the permeation data to the prediction of vacuum levels inside typical LTCC packaging is discussed. This data can further be utilized in designs to create LTCC packages that meet specific pressure/time operating requirements.
Lamination of LTCC at low pressure and moderate temperature using screen-printed adhesives
Authors: Maeder Thomas , Jiang Bo , Vecchio Fabrizio , Jacq Caroline , Ryser Peter , Muralt Paul
Published: October 2015

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 methods are applied after the tape processing steps and therefore require an extra operation in the processing chain, which may be unpractical, especially if the tape is very thin has been extensively cut.

In our procedure, the adhesives are printed and dried on the blanked tape before any other operation, with the drying step also useful for pre-conditioning the tapes, which may then be stored as "standard" blanks. The adhesives are formulated to have low tack at room temperature, making them compatible with standard processing, but to become very soft at 50–60°C, allowing lamination at low pressures. Compatibility with different tape materials is investigated, and the requirements for adequate adhesive formulation are discussed.
Low Temperature Co-fired Ceramics Processing Parameters Governing the Performance of Miniaturized Force Sensors
Authors: Weilguni Michael , Smetana Walter , Radosavljevic Goran , Nicolics Johann , Goebl Werner , Hofmann Alex
Published: October 2015

For the development of miniaturized force sensors, built up in ceramics technology with piezo-resistive principle, the compatibility of the piezo-resistive thick-film paste with the substrate and termination paste has to be verified. This paper deals with the compatibility of the ESL 3414-A piezo-resistive paste on HTCC (high temperature co-fired ceramics) substrates (alumina as reference and the partially stabilized zirconia tape ESL 42013-A) as well as on LTCC (low temperature co-fired ceramics) substrates (Heraeus AHT01-005, AHT08-047, CT707; and CeramTec GC) under different manufacturing conditions. The sheet resistance at room temperature, the longitudinal gauge factor at room temperature and the temperature coefficient of resistance have been measured. The results are compared with microscope images showing cracks in distinct cases. Finally, the compatibility and thus applicability of the ESL 3414-A on the investigated substrates is evaluated.
Design of Compact Transmission Line Transformers in LTCC Technology
Authors: Gartzke Eva , Götsch Dieter , Karmazin Roman , Männer Ruth , Matz Richard , Müller Jens
Published: October 2015

Concepts for ceramic integrated transmission line transformers (TLT) to conduct powers up to some kW and currents up to 10 A with an impedance ratio of 4:1 are presented. In this power range, a TLT usually consists of coaxial cables. To optimize size, improve integrability and enhance electric performance, our work pursues the integration into a planar multilayer board with electroplated conductors using Low Temperature Cofired Ceramics Technology (LTCC). The methodical design approach is presented, using complementary simulation tools for circuit, multilayer and FEM analysis to reach the aforementioned application-specific performance. Size is reduced further using specific ferrites and optimizing their position. The correlation between measured characteristics of various transmission line transformers produced and underlying design considerations are given in detail. Minimum sizes of 10 to 15 mm squared have been realized using single sided metallisation, which is also well suited for electroplating.
Comparison of Magnetic Characteristics and Structural Properties of Commercially Available Ferritic LTCC Materials
Authors: Blaž Nelu , Marić Andrea , Radosavljević Goran , Atassi Ibrahim , Smetana Walter , Živanov Ljiljana
Published: October 2015

The complex permeability values are the key parameters that determine properties of ferrite components. These parameters are very dependent on material structural properties and composition. This paper presents comparison of magnetic and structural properties of commercially available LTCC materials ESL 40011 and ESL 40012. The characterization sample, for each material, is a stack of LTCC tapes forming a toroidal shape structure sintered at peak temperatures of 885 °C. For both samples, scanning with electronic microscope was performed in order to determine differences in grain size and porosity. Energy-dispersive spectroscopy (EDS) was used for the elemental analysis of the samples. Obtained EDS spectrum for each samples are compared and analyzed. Permeability, for both materials are determined in the frequency range from 10 kHz to 1 GHz. Measurement procedures are divided in two segments - for low and high frequencies. For low frequency measurements method (from 10 kHz to 1000 kHz) with discrete turns of wire is performed using LCZ meter. On higher frequency range (from 1000 kHz to 1 GHz) method with short coaxial sample holder and Vector Network Analyzer is used. Obtained characteristics for complex permeability are presented and analyzed. It was determine that ESL 40011 has lower value for complex permeability but higher frequency range than ESL 40012. LTCC material ESL 40011 have maximal value 263 for real part of complex permeability at 2.3 MHz and ESL 40012 have maximal value 678 for real part of complex permeability at 0.5 MHz. Additionally, dispersion parameters of analyzed feritic materials are determined and compared.
Feasibility of Micro-Plasma Transistor Devices in LTCC
Authors: Mullner David , Garner Brooke , Plumlee Donald
Published: October 2015

The project will determine if making a novel micro-plasma transistor device (MPT device) in LTCC is feasible and advantageous. MPT devices control plasma, created by an antenna, by using electrodes. Using LTCC could be beneficial due to its properties involving plasma erosion and the ability for integrated 3D electronic construction. The layer construction of LTCC makes it relatively easy to implement the design, using five layers to produce a variety of configurations. The device will consist of source, gate, and drain electrodes on different layers of LTCC, with the antenna creating the plasma. The MPT device will be fabricated using DuPont 951 LTCC tapes and the ceramic MEMS fabrication process. A test matrix will be made to understand how micro-plasma transistors behave in LTCC. The matrix will include variations in hole diameter and operational parameters such as electrode configuration and voltage. The MPT device will be tested at BSU using a vacuum chamber and associated electronic hardware. After the tests are administered, the feasibility of micro-plasma transistors in LTCC will be determined.
Improving Performance of Laser-Printed Conductive Silver Lines
Authors: Büttner Dustin , Krüger Klaus
Published: October 2015

Within the last decade, large efforts were made to implement digital printing as a production method for printed electronics. Especially in production of thick-film electronics, innovation is pushed forward to overcome the lacks of established screen-printing regarding flexibility and tooling. Besides the numerous approaches in using ink-jet printing for printed electronics, researchers at Helmut Schmidt University already showed huge progress in applying electrophotography (“laser printing”) as a method to print conductive silver lines in order to form a conductive layout for thick-film circuits.

Electrophotography is a solvent-free method, able to directly print silver toner onto ceramic substrates, forming a conductive line after firing. Benefits are high speeds and flexibility and a huge potential regarding precision. Now, after the feasibility of the method was proven and even functional conductive layouts like RFID coils were printed, the next steps have to be taken towards developing electrophotography to an applicable method in a thick-film production process.

Thus, this paper describes the efforts in improving the method's performance. Different kinds of silver particles are tested towards their possibility of forming a silver toner. The resulting silver lines are examined regarding conductivity and printing precision. Also, surface treatment of substrates is considered as a method to reduce the number of required print cycles. Corresponding tests are performed. Furthermore, different firing profiles are tested towards their influence onto the resulting silver lines. Combining the results of these examinations, the performance of conductive silver lines could be improved significantly.
Ferrite–Polymer–Composite Materials for Inductive Electronic Components
Authors: Karmazin R. , Matz R. , Götsch D. , Hofmann R.
Published: October 2015

Based on the established inductor design rules, an innovative transformer was realized in a low-cost process using a novel ferrite-polymer composite material on conventional epoxy board. The low processing temperature (100°C), however, permits application also on other thermally sensitive substrates like semiconductor wafers. The transmitted power and efficiency of the transformer were 90W and 93%, respectively, as compared to 97% when sintered bulk ferrite cores are used.. The ratio of polymer and ferrite powder in the ferrite-polymer compound was chosen according to the Maxwell-Garnett mixing rule. With optimized particle size, ferrite content and microstructure, a permeability of up to μ = 30 is achieved. The achieved results are compared with theoretical predictions. The lower permeability of the ferrite-polymer composite in comparison to bulk ferrite material increases the lower limit of the frequency window of operation for this device.
Preparation of Integrated Passive Microwave Devices Through Inkjet Printing
Authors: Friederich A. , Kohler C. , Sazegar M. , Nikfalazar M. , Jakoby R. , Binder J. R. , Bauer W.
Published: October 2015

Barium strontium titanate (BST) is a promising material for passive tunable microwave devices such as phase shifters or tunable matching networks. This publication covers the preparation of BST thick-films for microwave applications through inkjet printing. Two barium strontium titanate (BST) inks were prepared, printed on alumina substrates and sintered at different temperatures. The first ink was prepared with pure BST and sintered between 1100°C and 1200°C. The second ink was prepared with a BST–ZnO–B2O3 composition and was suitable to reduce the sintering temperature down to 800°C. The microstructure of the thick-films reveals the evolution of grain growth with increasing sintering temperature in the thick-films. Furthermore, a reaction with the substrate was observed for both inks at high sintering temperatures. The microwave characterization of the thick-films shows that for the permittivity and the tunability of the films, the effect of grain growth and reaction with the substrate compete against each other. Hence, the optimal microwave properties were achieved at a transition temperature, where first additional phases could already be observed. Even though, the properties are poorer for lower sintering temperatures, the investigations show that the preparation of silver- or gold-based metal–insulator–metal (MIM) structures through inkjet printing is possible with this composition. This allows various new design concepts for partly or fully inkjet printed passive microwave devices. Furthermore, it gives the opportunity for a future integration of passive tunable microwave devices in a low temperature co-fired ceramic (LTCC) fabrication process.
Frequency and Time-Domain Performance of LTCC Transmission Lines Fabricated Using Multiple Printing Techniques
Authors: Bailey J. Phillip , Glover Michael D. , Decrossas Emmanuel , Porter Kaoru , Cannon Tom , Mantooth H. Alan , Hamilton Michael C.
Published: October 2015

The many advantages of low temperature co-fired ceramic (LTCC) materials are increasing their use in multi-layer systems containing multiple high-frequency / high-speed digital interconnects. Although construction of such interconnects is possible with current fabrication techniques, the loss exhibited by transmission lines at high frequencies limits their application by increasing system power consumption or requiring complex transceivers. Use of non-standard metal printing processes provides one possibility for realizing lower insertion loss desired for these interconnects. We have fabricated and evaluated representative single-ended and differential stripline transmission line structures using single, double, and mirror printing techniques for Ag metalization in DuPont 9K7 LTCC, to explore their suitability for high-frequency/high-speed applications. Discussion of analysis performed on cross-sections of these structures to determine post-firing geometry, as well as the level of fabrication control afforded over these parameters will be presented. To predict their performance for high-speed interconnects, 3D electromagnetic (3DEM) simulation models for characterizing the frequency performance of single-ended and differential structures have been also been developed. These 3DEM models have also been used in time domain simulations to verify digital signal capability by demonstrating structure performance at data rates exceeding 25 Gbps. Measurements of fabricated structures corresponding to the 3DEM models have also been performed in both the time and frequency domain and will be compared to the simulation results to confirm 3DEM model accuracy. The culmination of results from simulation and measurement will be used to present the differences, advantages, and disadvantages of each fabrication technique.
Fine Dust Measurement with Electrical Fields – Concept of a Hybrid Particle Detector
Authors: Geiling Thomas , Dressler Lothar , Welker Tilo , Hoffmann Martin
Published: October 2015

Fine dust measurements are only conducted at few locations in our daily environment, although it is getting clearer that fine dust poses a high risk on human health. A reason for this deficit is the lack of suitable measurement systems, especially for indoor environments. Of special interest are particles with critical dimension smaller than 10 μm. They constitute the highest risk to human health as they are not filtered out by the respiratory system. By miniaturizing particle detector concepts point-of-care applications are rendered possible and production costs can be greatly reduced with microsystem fabrication technologies. The pursued detector principle is based on the interaction of single particles with electric fields. The field is created within a micro-aperture machined in a silicon substrate. Two electrodes are deposited near the aperture and form a capacitive setup. An air flow drives particles through this aperture one by one. Passing particles distort the electric field, and their presence is detected by an impedance measurement. The changes induced by a single particle are tiny and require precise measurement circuits. Our contribution presents the design of a hybrid particle detector: The sensing element consists of an array of these micro apertures with lead-outs to a measurement circuit. This element is mounted on a LTCC module, which provides all necessary electrical and fluidic functions to operate the particle detector within a larger sensor platform. Sensitive parts of the measurement circuit are mounted on the LTCC module and positioned closely to the sensing elements. Microfluidic channels guide the air flow from the sensor platform to the micro-aperture and back. Therefore, the hybrid module is both: a ceramic interconnect and a ceramic microsystem.
Future Perspective of Materials and Processes of LTCC Technology Beyond Microelectronics Packaging
Authors: IMANAKA Yoshihiko
Published: October 2015

As semiconductor technology advances and computers become smaller with higher functionality, the technology has extended into a variety of areas, such as IT-enabled household electronics, ICT devices, electronic automobiles and ITS transport networks, to enrich people's lives. Packaging technology serves as a vital bridge between semiconductor chips and computer systems. Its considerable value is recognized in the constant contributions it makes in bringing about a prosperous life. This paper addresses the two mainstream areas of high-end computers and consumer products, with a special focus on the ceramic materials and process technology of the packaging technologies field at the primary packaging level. Drawing on the past and present developments in these areas as well as future prospects, the paper elucidates the significance of ceramics in packaging.
Room-Temperature Ceramic Nanocoating Using Nanosheet Deposition Technique
Authors: Osada M. , Sasaki T.
Published: October 2015

We present a novel procedure for ceramic nanocoating using oxide nanosheet as a building block. A variety of oxide nanosheets (such as Ti1−δO2, MnO2 and perovsites) were synthesized by delaminating appropriate layered precursors into their molecular single sheets. These nanosheets are exceptionally rich in both structural diversity and electronic properties, with potential applications including conductors, semiconductors, insulators, and ferromagnets. Another attractive aspect is that nanosheets can be organized into various nanoarchitectures by applying solution-based synthetic techniques involving electrostatic layer-by-layer assembly and Langmuir-Blodgett deposition. It is even possible to tailor superlattice assemblies, incorporating into the nanosheet galleries with a wide range of materials such as organic molecules, polymers, and inorganic/metal nanoparticles. Sophisticated functionalities or paper-like devices can be designed through the selection of nanosheets and combining materials, and precise control over their arrangement at the molecular scale.
3D FOCALIZATION MICROFLUIDIC DEVICE BUILT WITH LTCC TECHNOLOGY FOR NANOPARTICLE GENERATION USING NANOPRECIPITATION ROUTE
Authors: Gomez Houari Cobas , Gongora-Rubio Mario Ricardo , Agio Bianca Oliveira , Kimura Vanessa Tiemi , de Oliveira Adriano Marim , da Silva de Luca Ramos Luciana Wasnievski , Seabra Antonio Carlos
Published: October 2015

Nanoprecipitation is a nanonization technique used for nanoparticle generation. Several fields, like pharmacology and fine chemistry, make use of such technique. Typically are used a bulky batch mechanical processes rendering high polydispersity index of generated nanoparticles, poorly particle size reproducibility and energy wasting.

LTCC-based microsystem technologies allow the implementation of different unitary operations for chemical process, making it an enabling technology for the miniaturization of chemical processes. In fact, recently LTCC microfluidic reactors have been used to produce micro and nanoparticles with excellent control of size distribution and morphology.

The present work provides a report on the performance of a 3D LTCC flow focusing Microfluidic device designed to fabricate polymeric nanocapsules for Hydrocortisone drug encapsulation, using nanoprecipitation route. Monodisperse Hydrocortisone nanocapsules were obtained with sizes (Tp) from 188.9 nm to 459.1 nm with polydispersity index (PDI) from 0.102 to 0.235.
Aligned Co2Z Hexagonal Ferrite Fibers
Authors: Pullar Robert C.
Published: October 2015

The hexagonal ferrites, also know as hexaferrites, have become massively important materials commercially and technologically, accounting for the bulk of the total magnetic materials manufactured globally, and they have a multitude of uses and applications. They all have a magnetocrystalline anisotropy; that is the induced magnetization has a preferred orientation within the crystal structure. They can be divided into two main groups: those with an easy axis of magnetization, the uniaxial hexaferrites, and those with an easy plane (or cone) of magnetization, known as the ferroxplana or hexaplana ferrites.

There is currently increasing interest in composite materials containing hexaferrite fibers. It had been predicted that properties such as thermal and electrical conductivity, and magnetic, electrical and optical behavior will be enhanced in material in fibrous form. This is because a continuous fine fiber can be considered as effectively one-dimensional, and it does not behave as a homogeneously distributed solid. Although the intrinsic magnetization of the material is unaffected, the effective magnetization of an aligned fiber sample should be greater when a field is applied parallel with fiber alignment compared to when applied perpendicularly to fiber alignment. This feature was first demonstrated by the author for aligned hexaferrite fibers in 2006, who was also the first to synthesize fibers of BaM, SrM, Co2Y, Co2Z, Co2W, Co2X and Co2U hexaferrites, as micron-scale (3–10 μm) continuous fibers in both random and aligned blankets. The magnetic properties of aligned Co2Z (Ba3Co2Fe24O41) hexaferrite microfibers are presented in this paper.

It is shown that unlike with the uniaxial M ferrite fibers, the ferroxplana Co2Z ferrite fibers do not shown any significant alignment affects with direction of applied field. They have high Ms values in all orientations. This is attributed to the microstructure of these fibers, in which the hexagonal plates are stacked and oriented parallel to the fiber axis. This appears to counteract the expected effects of fiber alignment on measured Ms values.
3D-Shaping of Ceramic Tapes to Manufacture a High-Temperature Miniaturized Furnace
Authors: Kita Jaroslaw , Brandenburg Annica , Sudina Irina , Moos Ralf
Published: October 2015

This contribution shows results of 3D-shaping experiments of ceramic tapes. The structures were made by wrapping structured tapes around a hexagonal alumina rod. After lamination, the rod was removed and the structure was finally fired, similarly as reported in [1]. One out of many possible applications of such structures is a miniaturized furnace for sintering of critical materials, which could contaminate expensive chamber furnaces, for tempering of single gas sensors, or for fast heating at controlled rate. While LTCC technology can be applied only up to 600–700 °C, application of HTCC tapes can extend temperature range to above 1000 °C. Therefore, 99.99% alumina tape (ESL 44007) was used. The here-shown miniaturized furnace has a hexagonal form. For a proper temperature distribution in the furnace chamber, the furnace was equipped with six platinum heaters that can be controlled independently. Finite Elements Analysis (FEM) supported the design process. The paper discusses manufacturing route, beginning with a design process supported by FEM through 3D-shaping by wrapping structured tapes around an alumina rod and finally firing and functionality tests.
Comparison of Silver Sources for Silver/Glass Compounds by Multi-Material 3D-Printing
Authors: Polsakiewicz D. , Kollenberg W.
Published: October 2015

Inkjet printing of conductive silver lines on solid or flexible substrates for the fabrication of electronic components has been reported in a variety of ways over more than the last decade. Numerous publications highlight the importance of the silver source for the feasibility of the process as well as the resulting properties of the printed structures. In previous work [1] we reported the first experimental attempt to realize such conductive silver components inside a structure printed with a custom three dimensional powder printer. Aim of this study was to combine the functionality of directly printed functional elements with the geometrical flexibility of powder-based three-dimensional printing. While functionality in the printed glass/metallic compound is achieved in principle, an inhomogeneous microstructure with differentiated silver and glass areas is observed. In this article the silver source for the printing process is varied in order to achieve a homogeneous compound in desired areas. Three different metallic sources were used, namely a diluted screen-printing paste, a silver nitrate solution and silver particles formed by a previously reported polyol process. Ink were formulated from mentioned silver sources and printed with a glass powder. The fabricated samples are investigated in terms of their microstructure evolution and part functionality. The microstructure evolution is discussed in regard to the selected silver source. Additionally, the thermal treatment of the structures is optimized in order to ensure the optimum microstructure and part functionality. The reported experiments present the further development for a unique and novel method for fabricating glass/metal compounds by powder-based three-dimensional printing, allowing for the expansion of the process into novel applications.
Tolerance-optimized RF structures in LTCC for mm-wave frequencies applications
Authors: Balcells-Ventura Jordi , Klein Tobias , Uhlig Peter , Günner Carsten , Kulke Reinhard
Published: October 2015

Low Temperature Co-fired Ceramic (LTCC) is a well established technology for microwave space products and RF structures and it is a good candidate for these new frequency bands. Embedded passives are available to increase the density of integration even more. At higher frequencies structures become smaller and more prone to process tolerances. This challenge is addressed here with two novel mm-wave tolerance-optimized RF concepts in LTCC: load termination and Gysel power splitter. The concept presented here minimizes the effect of fabrication tolerances to provide stable RF response.
Dielectric Breakdown Mechanism of Perovskite-Structured Ceramics
Authors: Hoshina Takuya , Yamazaki Mikio , Takeda Hiroaki , Tsurumi Takaaki
Published: October 2015

We precisely measured the dielectric breakdown strength of SrTiO3, CaTiO3, and CaZrO3 ceramics as a function of temperature, and revealed the dielectric breakdown mechanism of the ceramics. For the dielectric breakdown test, ceramics specimens with a lot of round-bottom holes were prepared. Using the specimens, the breakdown positions were stabilized and a reliability of breakdown strength was improved as well as the measurement efficiency. As a result of the dielectric breakdown tests, it was found that the dielectric breakdown strength decreased with increasing permittivity at room temperature and the permittivity dependence of breakdown strength obeyed Griffith type energy release rate model. At high temperature above 100ºC, the dielectric breakdown mechanism of SrTiO3 and CaTiO3 ceramics was explained by an intrinsic breakdown model. In contrast, an intrinsic dielectric breakdown of CaZrO3 ceramics didn't occur in the measurement temperature range up to 210ºC. To obtain a high dielectric breakdown strength at high temperature, the dielectric permittivity is required to be low to some extent and the defect concentration of oxygen vacancies should be minimized in the perovskite-structured oxide.
Multilayered CRLH Metamaterials Using Magnetic Dipole-Like Resonant Dielectric Particles and Cut-Off TE Modes in Metallic Structures
Authors: Ueda Tetsuya , Sato Yoshiaki , Kado Yuichi , Itoh Tatsuo
Published: October 2015

Composite right/left handed (CRLH) metamaterial structures designed based on one-dielectric-resonator (DR) scheme in an epsilon-negative host medium are discussed. The scheme is a combination of dielectric and metals, but can avoid several problems often met in the other schemes composed of all dielectric metamaterials. The structure under consideration is composed of stacked layers including TE-cut-off metallic mesh plates with holes and dielectric layers with 2-D array of DRs. A volumetric multilayered 2-D CRLH structure that is impedance-matched to free space can be designed by optimally adjusting electromagnetic couplings between neighboring dielectric layers through metallic mesh holes. In addition, the multilayered structure is promising for easy fabrication of the 3-D isotropic CRLH metamaterials, compared to the other structures reported previously. It can support balanced CRLH propagation not only in the in-plane direction, but also in the direction normal to the layers. The structure has strong uniaxial anisotropy and polarization dependence, but the dispersion diagram can have almost isotropic characteristics in a specific frequency region by appropriately designing the configuration parameters.
Recent Advances in Practical Metamaterial Engineering
Authors: Rajab Khalid Z. , Fan Yifeng , Hao Yang
Published: October 2015

Metamaterials have been used to implement materials with near-zero and negative values of the relative electric permittivity (ɛ), as well as magnetic permeability (μ). These properties enable potentially significant applications, including superlenses, invisibility cloaks, and wideband artificial magnetic conductors. However, it has been proven that passive materials with these properties are necessarily narrow-banded and lossy. Active inclusions can be used to overcome these limitations, albeit at the expense of possible instability and noise issues, and added complexity. We examine a promising possible active implementation: the non-Foster circuit (NFC). Non-Foster circuits are used to create negative impedance loads, and have experienced widespread use for amplifying analog signals in trans-Atlantic telephony cables. There is also a long body of research into their applications for increasing antenna bandwidth. In this presentation, we demonstrate their application to multiple unit-cell metamaterials, and show their potential for possible performance improvements, including increased bandwidth and gain. We also show that maintaining stability is the primary difficulty in designing these complex systems, and has the effect of limiting the range of material properties that may be attained. Additionally, we examine noise and its effect as a mitigating factor in the performance of the metamaterial. Methods are demonstrated for designing robust, stable active metamaterials, and for analysing the noise figure of these structures. We conclude that, although noise and stability limits the bandwidths achievable with these active metamaterials, they still exhibit performances in excess of their passive counterparts, albeit at the expense of DC biasing-voltage requirements.
Stress and Strain Modeling of Low Temperature Cofired Ceramic (LTCC) Seal Frame and Lid
Authors: Krueger Daniel , Porter John , Peterson Ken
Published: October 2015

Low temperature cofired ceramic (LTCC) is established as an excellent packaging technology for high reliability, high density microelectronics. LTCC multichip modules (MCMs) comprising both ‘surface mount’ and ‘chip and wire’ technologies provide additional customization for performance. Long term robustness of the packages is impacted by the selection of seal frame and lid materials used to enclose the components inside distinct rooms in LTCC MCMs. An LTCC seal frame and lid combination has been developed that is capable of meeting the sealing and electromagnetic shielding requirements of MCMs. This work analyzes the stress and strain performance of various seal frame and lid materials, sealing materials, and configurations. The application for the MCM will impact selection of the seal frame, lid, and sealing materials based on this analysis.
Electric Micro-Propulsion in Low Temperature Co-fired Ceramics
Authors: Reis Derek , Taff Jesse , Plumlee Donald
Published: October 2015

This work focuses on the fabrication and assembly of miniature inductively-coupled plasma (ICP) electrostatic thrusters using DuPont's 951 Low Temperature Co-Fired Ceramics (LTCC). The use of LTCC allows for integration of electrical and fluidic features inside a hermetically sealed device that is resistant to plasma erosion. LTCC also allowed for the creation of cylindrical and planar structures which could be mated to form a single device. The thruster consists of a planar base, an antenna disc, and a plasma containment cylinder. The planar base contains internal fluid distribution channels as well as electrical interconnections. The antenna disc houses straight-through gas ports, electrical interconnects, as well as a planar spiral ICP antenna. The containment cylinder is used to contain argon plasma created by a radio frequency (RF) signal sent through the ICP antenna. The development of the fabrication process will be presented for the incorporation and alignment of all three LTCC components together to create a single thruster body. The results of the electrical and fluidic integration of the device will be evaluated and presented.
Pressure-Assisted Sintering of Buried Thick Film Resistors in LTCC
Authors: Heunisch Andreas , de Seauve Victor , Rabe Torsten
Published: October 2015

In this work, the effect of the pressure-assisted sintering process on buried thick film resistors integrated in LTCC multilayer has been studied. Four commercial resistor pastes with sheet resistivities between 10 kΩ and 10 MΩ/cm were analyzed. First they were characterized by SEM/EDX, XRD and Laser diffraction to determine composition and particle distribution. The pastes consist of isolating particles and of Ruthenium based particles that are supposed to build the conductive phase. The pastes were screen printed on LTCC green tape (DP 951) and buried in four layer laminates. Sintering was done in two ways, pressureless (PLS) and also pressure-assisted (PAS). The pressureless sintered resistors showed electrical resistance values roughly in the range of the nominal sheet resistivity and only relatively small fluctuation within one sample. The PAS samples on the other hand showed significantly higher resistances and larger deviations. The microstructure of the sintered resistors was again investigated by SEM and XRD. It seems that the resistivity is determined by the ratio of the two Ruthenium phases RuO2 and Pb2Ru2O6.5, where RuO2 has the higher conductivity. Buried resistors cannot be trimmed by a laser to adjust the resistance. But we discovered that a refiring step will reduce and normalize the resistivity of the PAS resistors significantly.