bluuebunny/crossref_metadata_2025 huggingface dataset:
Insulating properties of heat dissipation substrates (Al2O3 on Al) fabricated by aerosol deposition method
Authors: Suzuki Muneyasu , Akedo Jun
Published: October 2015

Much attention has been paid for heat dissipation ceramic substrates with a high thermal conductivity such as direct brazed aluminum (DBA) substrates and multilayer wiring substrates based on a low temperature co-fired ceramics (LTCC) processing, which are applied for insulated gate bipolar transistor (IGBT) modules of hybrid automobiles and heat dissipation substrates of LED array illumination. In general, sintered bulks are used for these insulating layers in DBA substrates. An aerosol deposition (AD) method based on an impact adhesion of the fine particles for forming of thick ceramic layers can be deposited ceramic thick films on metal substrates (e.g. Al, Cu) directly because of room temperature process. Since it is easy to obtain thick ceramic layers (thickness of > 1 μm) with a high insulating properties on metal substrates, high performance heat dissipation substrates with thinned insulating layer are expected to be created by using the AD method. In this study, Al2O3 dense ceramic films with thickness of up to 25 μm were deposited on Al substrates by the AD method, and their insulating properties have been investigated.
Influence of the latex binder type on alumina tapes lamination process
Authors: MALECHA Karol , JURKÓW Dominik , STIERNSTEDT Johanna , GOLONKA Leszek J.
Published: October 2015

In this paper, we have studied the influence of the pressure and type of latex binder on the lamination process. All experiments were performed at room temperature (25 °C) using four different lamination pressures (5, 10, 15 and 20 MPa). Two different alumina tapes developed by Swerea IVF were taken into account. The examined tapes contained different latex binder systems (LDM 7651S or Resicel E50). The quality of the laminated structures were analyzed before and after firing using optical microscopy. Moreover, the influence of the lamination pressure on the structures' surface roughness was investigated using profile measurements gauge. The performed experiments have shown which combination of lamination pressure and type of latex binder is the best to obtain defect-free multilayer ceramic structures.
Intelligent hermetically sealed LTCC Package with an integrated sensor system for avionics
Authors: Leschik Josef , Harasim Anton , Müller Jens
Published: October 2015

In this article, the fabrication process and the first results of a deep-drawn LTCC housing with integrated sensors in the field of avionic are presented This housing includes a pressure sensor that monitors the density of the housing - “self monitoring”. Furthermore, a humidity and a temperature sensor in the inner or outer layers of the LTCC decks are implemented, so that the internal state of the circuit can be monitored. Due to high integration (miniaturization) of the sensors the condition of the circuit can be monitored continuously. This allows the assembly upon the occurrence of an irregularity, such as the increase in moisture, to be replaced specifically. As a result, high costs in the field of material, maintenance, repairing und breakdown can be saved.
Manufacturing and Characterization of a Deformable LTCC Membrane with Integrated Temperature Sensors, Strain Gauges and Heating Structures
Authors: Gutzeit N. , Müller J. , Bruchmann C. , Gebhardt S.
Published: October 2015

The wavefront of high energy lasers can be corrected by using a deformable mirror. This mirror is a complex multimaterial device based on a LTCC membrane (DP 951) with a galvanically deposited and polished copper surface. In the membrane temperature sensors, strain gauges and heaters are integrated to measure deformation and temperature and to influence the latter. The laser wavefront is corrected by deforming the membrane with screen printed, segmented PZT thick film actuators.

In this paper the challenging manufacturing process of the mirror is described. During processing the LTCC membrane with integrated sensors must endure the postfired sintering of PZT at temperatures of up to 900°C without any degradation of the sensors' characteristics.

In order to optimize the sensors, various combinations of resistor and conductor pastes and different geometries are characterized. The usability and the performance of the sensor elements after temperature treatment are investigated by measuring the resistance and its resistance temperature characteristic.

For the detection of the membrane deformation, an array of miniaturized strain gauges is used. To achieve a controlled temperature distribution across the membrane different buried heater concepts are manufactured and characterized.

In order to improve the mechanical stability of the membrane, a rim of fired LTCC (width: 6 mm, diameter: 52 mm, thickness: 600 μm) is bonded to the multilayer membrane using a sealing glass.
Low-temperature sintered NTC ceramics for thick film temperature sensors
Authors: Reimann T. , Töpfer J. , Barth S.
Published: October 2015

Printed thick film NTC thermistors and multilayer devices are frequently used for temperature control in hybrid circuits. NiMn2O4 and substituted spinels are the most established materials for this application. For low-temperature sintering at 900 °C the shrinkage behavior of the thermistor material has to be adjusted by the addition of proper sinter additives.

We investigated the chemical stability of NiMn2O4 and substituted spinels in air between 25 °C and 1200 °C. The compound NiMn2O4 is stable from 700 °C to 970 °C only and interacts with the sinter additives. Stable cubic spinels were found in the system ZnxNi0,5Co0,5Mn2-zO4. Addition of liquid phase sintering additives to the spinel powders results in complete densification at 900 °C. No chemical interaction between spinel and additive was observed. The effect of Cu-substitution into the spinel was also investigated.

Functional NTC pastes were printed on alumina substrates and post-fired at 900 °C. The NTC thermistor films have a sheet resistivity of about 300 kOhm/sq and B = 3300 K. The firing behavior, microstructure formation and electric properties of NTC thick films will be reported.
Feasibility of screen-printed PZT microceramics for Structural Health Monitoring piezocomposites applications
Authors: DEBEDA Hélène , LAKHMI Riadh , FAVRE Isabelle , ARGILLOS Jonathan , MAGLIONE Mario , POMMIER-BUDINGER Valérie , HOCHART Xavier , SOURBE Wilfrid , LUCAT Claude
Published: October 2015

Using the association of the low-cost screen-printing technology with the sacrificial layer method, the feasibility of totally released piezoelectric thick-films microceramics of gold electroded PZT type is studied. After the deposition of the sacrificial layer on an alumina substrate and subsequent printing and drying of gold, PZT and gold layers, the final firing is performed at low temperature. This is followed by the releasing step of the Au/PZT/Au in diluted acidic solution. Impedance analysis shows that the electrical properties and electromechanical coefficients of poled PZT thick-films are still lower than those of PZT ceramics. This result is correlated to the high porosity rate of the PZT layer. However these piezoelectric microceramics present a good electromechanical behaviour and can be used as sensors when solicited by vibrations or as actuators to generate vibrations in a structure on which they are bonded. Moreover, the successful fabrication associated to a good electromechanical signature on a metallic test structure suggests Structural Health Monitoring applications.
Electromechanical Characterization of Bi-based Lead Free Ceramic Multilayer Actuators
Authors: Reichmann Klaus , Deluca Marco , Schütz Denis , Supancic Peter
Published: October 2015

The electromechanical behaviour of a lead-free ceramic multilayer actuator is described. The actuator is made of a Nd-doped bismuth-alkali-titanate ceramic with inner electrodes of an Ag/Pd-alloy. For electromechanical characterization the actuator is under constant mechanical load and the strain over the applied electric field is recorded. The mechanical load ranges from 0.1 to 80 MPa. The maximum applied electric field is 8 kV/mm. Starting with 0.1 MPa mechanical load the actuator exhibits a maximum strain of less than 0.1%. With increasing load the strain increases up to 0.17 % at 5 MPa. With higher load the strain decreases and reaches 0.125% at 80 MPa. Reducing the mechanical load leads to a steady increase in strain, which results in a doubling of the strain at 0.1 MPa compared to the initial value. The strain characteristic contains an electrostrictive part, a linear piezoelectric regime as well as some creep behaviour.
Transmit/Receive (T/R) Modules – Key Elements for Phased Array Antennas
Authors: Oppermann Martin , Schroth Joerg , Thurow Felix
Published: October 2015

Modern Active Electronically Steered Antennas (AESA) are operating in different platforms and systems. Inside EADS/CASSIDIAN the focus on X-Band antennas today is in airborne and fighter nose radars, in satellite based SAR antennas (Synthetic Aperture Radar) for earth observation and ground surveillance and security radars.

Active antennas are assembled with hundreds or even thousands of T/R modules. This paper will describe an example of a so called standardized module solution based on LTCC package technology. State-of-the-art modules are assembled with active components like MMICs realized in GaAs technology, e.g. Low Noise Amplifier (LNA) and High Power Amplifier (HPA), Silicon based devices and passives. Assembly technologies are optimized for high yield series production inside CASSIDIAN MicroWave Factory. New semiconductor technologies, like GaN (Gallium Nitride) are enablers for a new T/R module generation. GaN/SiC based MMICs with higher power density compared with GaAs based devices are technological challenges for innovative thermal management solutions and assembly alternatives. GaN power devices are soldered on modern heatsink materials with high thermal conductivity and matched CTE (between MMIC and heatsink).

Results of thermal simulations comparing different heatsink materials in combination with soldering techniques will be discussed and an optimized solution will be shown. Another type of T/R Module technology based on RF-PCB and packaged MMICs will be discussed. Future applications of ground-based security radars, active antenna products with a one-dimensional array and needs for cost-effective solutions seem to be SMD-based products. Different packages, e.g. QFN (Quad Flat Pack no Lead) and ceramic based (HTCC), mainly for power devices will be shown and compared.
Realization of High-Q Fano Resonances in Ceramic Dielectric Metamaterials for Sensing Applications
Authors: Semouchkina Elena , Hosseinzadeh Arash , Semouchkin George
Published: October 2015

Ceramic all-dielectric metamaterials are found to support very high Q resonances of the Fano-type, which until recently were largely attributed to the atomic physics phenomena. It is shown that proper arrangement of ceramic resonators in the metamaterial array allowsd for obtaining Q factors up to 15000. Thus high Q factors could be employed for new applications, in particular, for advanced sensing. An opportunity to design compact arrays that could be incorporated in a microwave sensor fed by a microstrip line is demonstrated. Numerical experiments have confirmed that Fano resonances in such arrays conserve high sensitivity to the dielectric permittivity of the controlled media.
Electromagnetic valve made in LTCC
Authors: Czok Mateusz , Czajkowska Kalina , Malecha Karol , Golonka Leszek
Published: October 2015

This paper describes technology of the electromagnetic valve made in the LTCC (Low Temperature Co-fired Ceramics). The actuation is supplied by mutual reaction between a 3D coil and a neodymium magnet bonded to flexible membrane. Such solution has many advantages like short reaction time, small power consumption and relatively great attractive forces. The valve is built in a hybrid PDMS-LTCC technology. The microfluidics and coil parts are fabricated in the LTCC technology. The flexible section is manufactured using a PDMS (poly(dimethylsiloxane)) membrane bonded to the ceramic part by plasma oxidation. The magnet is fixed on the membrane surface. The LTCC material was chosen for the sake of chemical durability and possibility of 3D structures creating. The PDMS membrane provides simultaneously very good stability and high flexibility.
LTCC-3D FLOW FOCUSING FLUIDIC MICROREACTOR FOR NANOPARTICLE FABRICATION AND PRODUCTION SCALE-OUT
Authors: Gongora-Rubio Mario Ricardo , de Novais Schianti Juliana , Gomez Houari Cobas , Teves Andre da Costa
Published: October 2015

Miniaturization of chemical processes is becoming a must for green chemistry and sustainable industry processes, so technological research in this direction is well received. Continuous microreactor systems hold many potential benefits over batch reactors allowing: high surface-to-volume ratio, fine adjustment of chemical reaction residence times, small thermal inertia and fast changes in temperature. Advantages of multilayer green ceramics for microprocess applications include: LTCC substrate is chemically inert to most solvents, it has a high contact angle, presents low thermal coefficient of expansion, can withstand high operational temperatures and high internal pressures. For these reasons, 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 reactor designed to fabricate Nanoparticles using nano precipitation through an anti-solvent, with electric potential size tuning. We also implement an approach to nanoparticle production scale-out.
Characterization of Low Temperature Sintered Ferrite Laminates for High Frequency Point-of-Load Converters
Authors: Zhang Wenli , Mu Mingkai , Hou Dongbin , Su Yipeng , Li Qiang , Lee Fred C.
Published: October 2015

The high power density Point-of-Load (POL) converter with high operating frequency has gained increasing interest in the growing market for portable communications and handheld electronics. Low profile magnetic components and associated integration techniques are desired for design and fabrication of highly integrated POL converters. Low fired ferrite tapes for multilayer chip inductors and high frequency applications have been developed and used in hybrid integration of power modules. The inductor made of multilayer ferrites can be fabricated as the magnetic substrate in an integrated POL converter with active components on top. The developed 3-D integration approach is applied to reduce footprint and increase power density for the high frequency POL converter.

The current work reports the characterization of magnetic properties, microstructures, and chemical compositions of commercially available low-fire Ni-Cu-Zn ferrite materials (ESL 40010, 40011, and 40012) and their mixed laminates. Permeability and core loss density are measured on toroidal shaped samples sintered at 885 °C for 3.5 hrs. Because high DC current is always applied to bias the core for the inductors used in high frequency POL converters, the influence of superimposed DC bias on the magnetic properties of ferrite laminates has also been evaluated. The microstructures and chemical compositions of low temperature sintered ferrite laminates are observed and analyzed in order to explain the difference of magnetic properties among samples. The mixed laminate with alternating layers of ESL 40010 and ESL 40012 in 1:1 ratio presents the highest permeability and the lowest core loss density among all examined samples when DC bias is above 1000 A/m. Finally, a 12 V to 1.2 V, 15 A, high frequency (1.5–5 MHz) integrated POL converter with laminated ferrite inductor has been fabricated and demonstrated working at high efficiency with power density as high as 1000 W/in3.
Sintering and Foaming of Barium and Calcium Silicate Glass Powders
Authors: Blanco B. Agea , Blaess C. , Reinsch S. , Brauer D. , Müller R.
Published: October 2015

Sintering and foaming of barium and calcium silicate glass powder compacts have been studied for different powder milling. Sintering was measured by means of heating microscopy backed up by XRD, DTA, Vacuum Hot Extraction (VHE) and electron microscopy. Foaming intensity strongly increased with decreasing glass particle size. Although powder compacts were uniaxially pressed and sintered in ambient air, foaming was affected by the milling atmosphere and most intensive for milling in CO2. Conformingly, VHE studies revealed that foaming of fully sintered samples was mainly driven by CO2, even for powders milled in technical air, Ar and N2. Prolonged storage of air milled barium silicate glass powders in ambient air before pressing and sintering caused further increase of foaming intensity. These findings indicate that carbonaceous species are preferentially trapped to or close beneath the powder surface during milling and later storage. The temperature range of CO2 degassing from fully sintered barium and calcium silicate glass powder compacts fits the temperature ranges of decomposition of BaCO3 and CaCO3 mix-milled with the respective barium and calcium silicate glass powders.
Corrosion of Borosilicate Glasses
Authors: Weber Constans M. , Stockmann Jörg , Rosier Elisabeth
Published: October 2015

In contact with aqueous media glass tends to corrode leading to different surface properties. For the precision application this alteration might cause product failure. Hence precise knowledge of the surface interactions is essential. We performed an extensive investigation on the behavior of borosilicate glass under corrosive attack in order to identify critical processes. We identified appropriate investigation methods including sequential chemical analysis, ATR-IR, ellipsometry and SNMS. These techniques allow to identify the influence of specific production processes.
Requirements on glasses for femtosecond-laser based micro-structuring
Authors: Seuthe Thomas , Grehn Moritz , Mermillod-Blondin Alexandre , Bonse Jörn , Eberstein Markus
Published: October 2015

In this work, glasses with systematically varied compositions were manufactured and irradiated by single Ti:sapphire fs-laser pulses (800 nm, 120 fs), focused at the surface and into the bulk of the glass materials. The samples were tested for their ablation threshold fluence as well as for structural changes using μ-Raman-spectroscopy. Correlations between the glass composition, the material-ablation on the glass surface and the permanent changes of the refractive index inside the glass volume after the irradiation by fs-laser pulses were obtained. The results show, that the structural modifications found at the surface of the glasses and inside its volume are closely related. However, while the ablation threshold fluence of the glass surface primarily depends on the glass dissociation energy, the permanent refractive index change inside the volume is rather determined by its ability for absorbing the fs-laser pulses and the subsequent relaxation processes. The results of this work provide some guidance on how the glass composition can be varied in order to optimize the fs-laser induced modification of dielectrics.
LTCC MICROREACTORS APPLICATION IN A MICROFLUIDIC INTEGRATED SYSTEM FOR HYDROPHOBIC DRUG ENCAPSULATION IN POLYMERIC NANO/MICROPARTICLES
Authors: Rincon Ardila L. K. , Cobas-Gomez H. , Feitosa V.A. , Kimura V.T. , Paiva O. , Oliveira A. M. , Cerize N.P. , Ramos L.W.S.L. , Gongora-Rubio M. R.
Published: October 2015

Nanotechnology develops methods and processes for Drug Delivery Systems (DDS) based on the fabrication of polymeric nano/microparticles with encapsulated drug that can be applied for maximize therapeutic activity and minimizes undesirable effects. However, these processes entail several conditions to operate efficiently. They present high sensibility to changes in temperature, flow rate, pressure, and chemical solution composition. An optimal configuration of these parameters is required to guarantee stable particle production. For these reasons, integration of technological devices like sensors, actuators, microfluidic devices and control systems is essential to increase particle production performance. The proposal of this work is to develop an integrated monitored and controlled system using LTCC (Low Temperature Co-Fired Ceramic) microreactors to generate polymeric nano/microparticles for encapsulation of hydrocortisone drug with PCL and Pluronic polymers. The microfluidic integrated system is developed through devices integration, system characterization and control loops configuration, using pressure sensors, syringe and microgear pumps, mixer and vortex LTCC microfluidic reactors, communication drivers, and data processing/control programs. Dynamic Light Scattering, Optical and Scanning Electron Microscopy were employed to measure particle size, polydispersity (PdI) distribution and particle morphology. Preliminary results showed nano/microparticles with encapsulated hydrocortisone drug having a mean diameter size of 528–816 nm and Polidispersity Index (PdI) < 0.5.
Structuring of LTCC Substrates by a Combination of Pressure-Assisted Sintering and Hot-Embossing
Authors: Brandt Bjoern , Rabe Torsten
Published: October 2015

A novel technology for the structuring of LTCC surfaces is introduced. The material is shaped in a zero-shrinkage process by embossing a glassy carbon mold into the softened LTCC directly after termination of the shrinkage. Three commercially available LTCC compositions (Ceramtape GC, Heratape CT707, and DP951) were tested. Diverse raised and lowered structures including rings, grids, and characters were fabricated. Different material behavior was observed for the tested compositions. Promising results were achieved with Ceramtape GC. Embossing of precise, 40 μm deep circular cavities and 50 μm high raised characters is demonstrated. Processing of 100 × 100 mm2 substrates is possible. DP951 showed very good moldability, but also unwanted material displacement due to evaporating lead. A high displacement capacity but uneven heights of embossed structures were observed on CT707 samples. SEM investigations proved the precise transfer of surface contours from the mold to the LTCC. Thereby, the high potential of the hot-embossing process for micro-patterning of LTCC is illustrated.
Surface Characteristics of LTCC Substrates Fabricated by Pressure-assisted Sintering
Authors: Brandt Bjoern , Rabe Torsten
Published: October 2015

Plane LTCC substrates can be produced in zero-shrinkage technology by pressure-assisted sintering. The application of axial pressure during sintering supports densification, enhances co-firing of different materials and restrains deformation. However, the sintered surfaces are affected from the release tapes and setters used in the pressure-assisted sintering process. In this study, the effect of release tape particle size on the surface properties of sintered substrates was investigated. Moreover, the substitution of release tape by the use of a vitreous carbon setter was tested. Surface roughness and sheet resistances of metallic thin-films on the respective samples were determined. It was found, that roughness of the substrates is not directly correlated with the adequacy of the surface for thin-film deposition. Compared to a freely sintered sample with an average roughness (Ra) of 0.31 μm, pressure-assisted sintering created smoother surfaces using fine-grained tapes (Ra = 0.18 μm) and rougher surfaces using coarse release tapes (Ra = 0.46 mm). Still, sheet resistances were higher on all sinter-pressed samples. The vitreous carbon setter created unusual, trenched surfaces structures, characterized by varying roughness values and intermediate sheet resistances on the LTCCs tested.
In Situ Characterization of the Sintering Behavior of LTCC Laminates with Embedded Cavities by High Temperature Laser Profilometry
Authors: Heunisch Andreas , Marzok Ulrich , Münchow Marco , Müller Ralf , Rabe Torsten
Published: October 2015

Three-dimensionally structured LTCC multilayer with channels and inner cavities are required for numerous applications like microreactors, microfluidic systems or sensors. For the performance of such devices, the dimensional accuracy of the embedded structures is crucial. In the green state, the desired structures can be precisely implemented in the LTCC tapes by laser cutting, punching or milling. Unfortunately, during lamination and sintering, shape integrity of cavities and channels is notably affected by warpage and deformation.

To investigate the sintering behavior of structured LTCC laminates, a newly developed High Temperature Laser Profilometer (HTLP) can be used. The HTLP allows 3D in-situ shape detection of flat ceramic samples and tapes all along the sintering process. It is applicable for temperatures up to 1000 °C and sample sizes up to 200 mm × 200 mm × 10 mm. During a measurement, the rotating sample is scanned spirally by a linearly moving laser distance sensor through a slot in the furnace top wall. Distance and position values deliver a 3D surface image of the sample. Current lateral dimensions, which are determined by sintering shrinkage, can be measured continuously. Local deformation and warpage can be visualized time- and temperature-resolved.

This new method was used, to analyze the sintering behavior of LTCC multilayer laminates containing large size cavities. These were fabricated out of punched green sheets by low pressure lamination without inserts. Samples with cavities of varying cross sections, as well as cavities with and without connection to the surface were observed.
Electroplating and Electroless Plating Process Development for DuPont™ GreenTape™ 9K7 LTCC
Authors: Beikmohamadi Allan , Stewart Steve , Parisi Jim , McCombs Mark , Smith Michael , Souders Ken , Malerbi J.C. , Nair K.M. , Nair Deepukumar , Farb Michael
Published: October 2015

Low Temperature Co-fired Ceramic (LTCC) technology provides an attractive packaging platform for microwave and millimeter wave circuits and systems due to its unique properties. Generally, thick film gold or silver conductors are used as metallizations on LTCC substrates along with occasional use of copper thick films. This paper reports methods and results of extensive process development experiments DuPont Microcircuit Materials has undertaken to establish a commercially viable plating process for the market leading DuPont™ GreenTape™ 9K7 LTCC system. Both Electroplating and Electroless plating processes are investigated in this work. These techniques provide certain advantages when used in isolation or in combination with standard thick film metallizations, helping to extend their applicability. Electroplating of copper on LTCC provides a means of using copper as the external conductor without having to use complicated firing processes in oxygen-free atmosphere as required for copper thick film. This approach leads to a much more cost effective approach if copper is required as the external metal. Electroless Nickel/Gold plating (ENIG) of both silver and copper (electroplated and/or thick film) provides an industry standard, highly reliable, robust surface finish. Such surface finish enables easy integration of both soldering and wire bonding processes.
Miniature Lowpass Filters in Low Loss 9k7 LTCC
Authors: Dai Steve , Hsieh Lung-Hwa
Published: October 2015

DuPont 9k7 low temperature cofired ceramic (LTCC) is a low loss, or high quality factor Q, tape system targeting at radio frequency (RF) applications. This paper reports the effect of a critical process parameter, heating rate, on the densification and dielectric properties of the 9k7 LTCC. The role of competing densification and crystallization during the sintering of 9k7 is discussed. The high Q of DuPont 9K7 can be used to improve RF system performance, for example a better receiver noise figure, by designing embedded passive RF components such as inductors, capacitors and filters. Miniaturized multilayer low pass filters (LPF) with a wide stopband were fabricated to showcase the technology.
LTCC SOLUTION FOR MILLIMETER-WAVE AUTOMOTIVE SHORT-RANGE RADAR APPLICATIONS
Authors: Wang Xin , Brunner Sebastian , Stadler Manfred , Stelzer Andreas , Aichholzer Klaus
Published: October 2015

In this paper we present the usage of low temperature co-fired ceramics (LTCC) technology for 79-GHz automotive short-range radar application. Normally, for a radar system the size of the RF-frontend is mainly determined by the antenna aperture. As the working frequency shifts from 24 GHz to 79 GHz, the antenna aperture reduces enormously (as well as the overall-size of the RF-frontend), which also reduces the price difference between the RF-frontends realized on LTCC and on the traditional organic substrate. Further, LTCC offers an extra degree of freedom for designing vertical parallel-feeds for wideband applications. Complex structures like laminated waveguide can be used for a highly integrated RF-frontend solution. In this work, special attention was paid on the material properties, the antenna, the design concept, the process for the outside metallization layers, the solder mask, and the integration possibility. To showcase the result, a 79-GHz LTCC RF-frontend combined with a monolithic microwave integrated circuits is demonstrated with measurement results.
Wide Band Measurement of Dielectric Properties of Electronic Assembly Materials Inside a LTCC Fluidic Structure
Authors: Müller Jens
Published: October 2015

Assembly materials like underfillers or glob top epoxies are typically not specified regarding their dielectric properties for frequencies higher than 1 MHz. However, their behavior should be known for a wider frequency range in order to implement the right parameters for RF and microwave simulations and designs. Typical methods to measure permittivity and loss tangent are based on parallel plate capacitor measurement with an impedance or network analyzer (up to about 1 GHz), S-parameter measurement of filled wave guides or coaxial transmission lines or resonance methods (e.g. split post resonator, slit cavity resonator, ring resonator, open resonator). Most of these methods require specific sophisticated sample preparation. The paper describes a novel method based on suspended or inverted microstrip evaluation in a 3D LTCC structure. Suspended and inverted microstrip lines have lower insertion losses than standard microstrip lines due to the air gap between the line and the ground plane (reduced dielectric losses). Low loss structures are necessary to be able to measure low loss dielectrics. Such suspended or inverted microstrip lines can be easily achieved in LTCC by implementing a cavity structure. In- and outlets allow filling the cavity with fluids after an initial S-parameter measurement of line properties (impedance, insertion loss, phase velocity). Measuring is repeated once the assembly material is cured. The change in impedance, phase velocity and insertion contains the information about the material under test. Its properties are derived by curve fitting methods with a 3D electromagnetic field simulator. It is also possible to implement line resonators instead of through lines. In the latter case, the resonant frequency shift and the quality factor contains the material information. The procedure is demonstrated on a multilayer LTCC substrate based on low loss DP 9k7 and a commercial underfill material.
Nonlinear Transmission Lines Using Substrate Integrated Waveguides in LTCC
Authors: Caudle Byron , Baginski Michael , Hamilton Michael
Published: October 2015

The generation and transmission of relatively short duration, broadband, peak pulse power bursts has numerous applications in the communications and defense sectors. In the past, nonlinear transmission lines (NLTLs) have been used to create such broadband pulses. While most NLTL designs are based on nonlinear capacitors or inductors arranged in a ladder network, the method presented here replaces the transmission line with a novel ferroelectric filled waveguide. When a large transient voltage is input to the guide the resulting electric field will cause the polarization field to move into the saturation region. This reduces the effective dielectric permittivity and thus the group velocity of the peak power portion of the wave is faster than all other portions of the pulse. This results in the middle portion of the pulse overtaking the leading edge and “piling-up” energy at the front edge of the pulse, creating what appears to be a temporal compression of the leading edge. The temporal compression results in increased harmonic spectral content. The simulated NLTLs can be fabricated using Substrate Integrated Waveguides (SIW) in low temperature cofired ceramics (LTCC). Closely spaced vias form trenches in the waveguide that are used to create space for the nonlinear dielectric and the trenches are filled with ferroelectric materials using a sol-gel method. The trench dimensions and type of ferroelectric fill material for each layer are determined using a genetic algorithm optimization routine that produces a maximum rise time compression of the input pulse.
Printing of Ultrathin Nanoparticulate Indium Tin Oxide Structures
Authors: Wegener Moritz , Spiehl Dieter , Mikschl Florian , Liu Xinxin , Roosen Andreas
Published: October 2015

This contribution focusses on three printing techniques: inkjet printing, flexographic printing and gravure printing for the manufacture of ITO structures based on nanoparticular ITO inks. The quality and stability of nanoparticular inks depends mainly on the dispersing step and is reflected by the achieved particle size distribution. The particle size distribution of the ITO inks has a distinct influence on the optical and electrical properties of the deposited ITO structures. The optimization of nanoparticular ITO inks concerning rheological behavior, wetting behavior and resulting material performance is presented. Inkjet printing was used as a low speed method to manufacture structures in the range of 30 μm. It is shown how coffee-staining, a frequently arising problem in inkjet printing, can be prevented by different strategies. Nanoparticular ITO structures with layer thicknesses clearly below 1 μm were printed. Gravure and flexography printing are well-established industrial printing processes with printing speeds above 100 m/min. These high-speed printing processes were used to print structures on PET film and glass substrates. Different solvents, e.g., water and ethanol, solvent compositions and binder types were varied to optimize the resulting ITO structures. The printed structures in the range of 10 to 2000 μm with thicknesses down to 1 μm were evaluated concerning surface topography and electrical conductivity. The high inter-grain porosity and the used organic additives limit the electrical conductivity of nanoparticulate ITO structures. To further improve their electrical conductivity laser post-treatment of printed ITO structures was performed.
LTCC Piezoelectric Transducer for Energy Harvesting
Authors: Dabrowski Arkadiusz P. , Owczarzak Slawomir , Roguszczak Henryk , Golonka Leszek J.
Published: October 2015

In this paper, design, technology and properties of multi cantilever transducer for energy harvesting application were described. The piezoelectric transducer was made in LTCC (Low Temperature Cofired Ceramics) technology using PZT (Lead Zirconate-Titanate) based tape. In such devices the highest power can be reached at resonance frequencies of the cantilevers. Eight bimorph transducers with lengths corresponding to 33, 50, 58, 66, 75, 82, 91 and 100 Hz resonant frequency, were designed. The transducers were polarized in serial or parallel configuration. To avoid voltage reduction in the system of a few piezoelectric bimorphs, rectifiers were applied for each cantilever.

Transducers had optimum resistance in ranges of 60–140 kΩ and 300–600 kΩ for bimorphs poled in parallel and serial configuration, respectively. The mean output power under sinusoidal excitation with 20 μm vibration amplitude calculated from all maxima at resonant frequencies for optimum load, were equal to 10.3 μW and 12.4μW for parallel and serial configurations with rectifier. Without rectifier the values were equal to 18.2 μW for both the transducers. In case of mean output power, the difference between both the transducers was not really significant, however at higher frequency the maximum power was higher for serial configuration. Besides, the output voltage obtained in serial bimorph was higher than in parallel one. The mean power density for all the resonant peaks measured at 0.41 g was equal to 210 μW/cm3/g and 360 μW/cm3/g with and without rectifier, respectively.
Silver Metallization on Porosified LTCC Deposited by Pulse Plating Technique
Authors: Steinhäußer Frank , Sandulache Gabriela , Hansal Wolfgang , Bittner Achim , Schmid Ulrich
Published: October 2015

Present microelectronic devices especially when including high frequency applications are in need of highly integrated metallization technologies. Silver is considered as a future interconnection material for such devices and systems due to its low bulk resistivity of about 1.6 μΩ·cm at 20°C. Conventional thick film metallization techniques on low temperature co-fired ceramics such as screen printing are only partly capable of meeting the requirements in terms of lateral resolution and precision. Furthermore, on advanced surfaces such as porosified composite LTCC, also thin film metallization techniques (e.g. sputtering) meet their limits due to a poor coverage and hence, a low electrical conductivity. In this study, it is shown, that bipolar pulse plating of silver is capable of bridging the pores of the surface of the porosified substrate without penetrating them. The plated metallizations feature very fine grains with an average diameter of approx. 90 nm and a maximum up to 250 nm. The film resistivity being measured directly during annealing decreases at elevated temperatures above 90°C in air. Compared to the bulk value, the film resistivity of the ‘as deposited’ electroplated silver is increased, but can be improved down to 2 μΩ·cm with a TCR of 4.1·10−3 K−1 at 20°C by a subsequent annealing treatment at 500°C for 5 h in air. Since there is no measureable difference in resistivity between the galvanic silver deposited on non-porosified or porosified LTCC detected, the findings qualify the bipolar pulsed silver plating as an excellent choice for metalizing porosified LTCC substrates.
The influence of glassy carbon on tribological properties in metal – ceramic composites with skeleton reinforcement
Authors: Myalski Jerzy , Hekner Bartosz , Posmyk Andrzej
Published: October 2015

This paper presents a results of mechanical and tribological properties of aluminum based composites with skeleton reinforcement. The aluminum alloy based composites were produced using pressure infiltration process. As a reinforcement ceramic foam with opened cells was applied. This reinforcement structure give an opportunity to limit the most common defects (like agglomeration, inhomogeneity, ect.) occurring in composite materials obtained by casting. In presented research three different types of porous foam were analysed. There were alumina foam covered by thin glassy carbon layer (Al2O3 – GC) and two types of glassy carbon foams (GC). Due to application of porous ceramic foam, an increasing of composite mechanical properties are expected. An additional glassy carbon layer with thickness up to 5 μm was applied for increasing a thermal conductivity and rapid heat dissipation from the material. Moreover, the skeleton structure of glassy carbon, and its wear mechanism, should decrease a friction coefficient value. Two manufactured types of composites: Al2O3 – GC foam and own produced glassy carbon foam were compared with material reinforced by spatial carbon structure obtained from commercial RVC (produced by Reynolds) foam.

The results showed that the application of porous ceramic and ceramic – carbon reinforcement skeletons led to increasing of mechanical properties of composite. The conducted research using pin–on–disc method, with 2,5 MPa of load and 1,0 m/s of speed revealed that glassy carbon have significant influence on decreasing friction coefficient and wear rate. An analysis of material external layer in areas after coupling with pin (wear track) indicated a fragmentation of glassy carbon foam. The wear products are not remove from friction surfaces, but these products create thin carbon film with lubricant properties. The conducted research showed both, a possibility to produce composites with skeleton structure of reinforcement and a possibility of correction of material tribological properties using glassy carbon.
Simulation of the working range of an implantable hearing aid transducer by use of different piezoelectric materials
Authors: Koch Martin , Essinger Till Moritz , Bornitz Matthias , Stoppe Thomas , Zahnert Thomas
Published: October 2015

A piezoelectric membrane transducer which offers an approach to treat sensorineural hearing loss is introduced. The sensor and the actuator element each consist of a titanium membrane with a single crystal piezo and are clamped into the same assembly housing. The transducer is placed into the incudostapedial joint gap (between incus and stapes ossicle) which offers a straightforward implantation after the drilling of an access through a mastoidectomy which is state of the art for otology surgeries. The sensor is measuring the force transmitted through the ossicular chain onto his membrane on the incus-side of the housing. An associated signal processing drives the actuator at the opposite side of the sensor to amplify the movement transmitted by the ossicular chain to the inner ear. The movement of the stapes footplate is related to the hearing perception. Therefore the proposed concept can be used as part of a fully implantable hearing aid. A finite elemente model (FEM) of a transducer is built and implemented in a existing FEM model of the middle ear. Both sensor and actuator performance span up a working range for the transducer which ranges from about 20 to 30 dB SPL up to 90 to over 120 dB SPL. In this study the range of the workspace is evaluated in dependency of the chosen piezoelectric material which can lead to significant changes of the results.
Micro-Positioning Stages for Adaptive Optics Based on Piezoelectric Thick Film Actuators
Authors: Gebhardt Sylvia , Ernst Dörthe , Bramlage Bernhard
Published: October 2015

Piezoceramic actuators based on thick film technology offer the opportunity of integrated solutions for smart microsystems. Especially in adaptive micro-optics, where the height of devices is limited, outgassing has to be inhibited and complex actuator structures are required, screen printed actuators are of great interest. The paper highlights our recent research on micro-positioning stages for integration into a plenoptic camera. The first concept is based on through-thickness polarized lead zirconate titanate (PZT) thick films printed on a 45 mm × 44 mm × 0.17 mm LTCC (Low Temperature Cofired Ceramics) frame with 4 mm wide legs. Driving with an electrical field of 2 kV/mm resulted in an upright stroke of 115 μm. The second concept combines through-thickness and in-plane polarized thick films on four cantilever beams of an Al2O3 based micro-positioning stage. Because of the combination of d31- and d33-mode of excitation, each cantilever beam will provide an s-shaped bending profile allowing for a planar and tilt free lift of 130 μm at 1.66 kV/mm. Both actuator concepts were exploited to adjust position of a micro-lens array between main lens and image sensor in a plenoptic camera setup. With that, working range of the plenoptic camera could be extended.
Fabrication of Diamond Photonic Crystals with Oxide and Metallic Glasses Lattices for Terahertz Wave Control by Micro Pattering Stereolithography
Authors: Kirihara Soshu , Nakano Maasa
Published: October 2015

Diamond lattice type photonic crystals with periodic arranged magnetic and dielectric materials can reflect the terahertz waves through Bragg diffraction. The fine diffraction lattices were fabricated successfully by using micro patterning stereolithography of computer aided designing and manufacturing methods. In this process, the photo sensitive acrylic resin paste mixed with micrometer sized metallic glass and oxide glass particles was spread on a glass substrate with 10 μm in layer thickness by using a mechanical knife edge, and cross sectional images of ultra violet ray were exposed with 2 μm in part accuracy. The high resolution exposure could be realized by using a digital micro-mirror device. The micro mirrors of 14 μm in edge length were tilted individually by piezoelectric actuators. Through the layer by layer stacking, the micrometer order metallic glass and oxide glass composite structure was formed. The magnetic and dielectric composite lattices could be obtained through the dewaxing and sintering process with the lower temperature of 400 ºC under the transition point of metallic glass and above the melting point of oxide glass. The amorphous structure formation after the heat treatment was verified by a X-ray diffraction analysis. A transmission spectrum of electromagnetic wave in terahertz frequency ranges for the formed magnetic and dielectric crystals with a diamond lattice structure was measured by using a terahertz time domain spectroscopy.
Substrate integrated MM-wave antenna utilizing metalized cavity walls
Authors: Balcells-Ventura J. , Leiss J. , Uhlig P. , Ihle M. , Ziesche S. , Bisognin A. , Luxey C.
Published: October 2015

This paper presents an aerosol-printed horn-shaped antenna on LTCC designed to operate in the 60 GHz frequency range. This design shows the potential of combining screen- and aerosol- printing to manufacture LTCC integrated antennas at mm-wave frequencies. The antenna not only shows good matching and radiation properties, but is also ideally suited for highly integrated RF-buildups. The aim of this paper is to present the manufactured demonstrator and its RF characterization.
Design of Small-size and Low-loss LTCC Filters on Capacitively Loaded Cavities
Authors: Turgaliev Viacheslav , Kholodnyak Dmitry , Müller Jens , Hein Matthias A.
Published: October 2015

Design of microwave filters for portable electronics is complicated by conflicting requirements to be met simultaneously such as high selectivity, low insertion loss and compact size. Substrate integrated waveguide (SIW) technology allows designing low-profile high-Q resonators and low-loss bandpass filters based thereof. However, SIW filters are not well-suited for telecommunication applications because of remarkably large size in plane. The size of a SIW cavity can be dramatically reduced by a capacitive loading. Capacitively loaded cavities (CLCs) operating in the TM110 mode can be as small as 1/8 of the guided wavelength and even smaller, i.e. comparable in size with lumped-element resonators. Although the unloaded Q-factor decreases proportionally to cavity size, miniaturized CLCs can exhibit much higher Q-factor than that of lumped-element resonators. This paves the way for designing small-size and low-loss filters for wireless communications and different applications. Miniaturized capacitively loaded SIW cavities are favorably implemented by means of the low temperature co-fired ceramics (LTCC) technology. The goal of the paper is to demonstrate manifold possibilities and flexibility offered by the LTCC technology to the design of advanced microwave filters on CLCs. Different design and manufacturing aspects are considered. Various design examples of high-performance LTCC resonators and filters for single- and dual-band wireless applications are presented. The designed resonators and filters were manufactured using the commercial DuPont Green Tape 951 LTCC system. The LTCC filters on miniaturized CLCs are shown advantageous with regard to small size, low loss, and absence of spurious response over a wide frequency range.