bluuebunny/crossref_metadata_2025 huggingface dataset:
Improved RF Metamaterial Band-Pass Filter Design Using CSRR Structures on LCP Substrate
Authors: James Christopher , Dean Robert N.
Published: October 2015

In the past decade, the emergence of man-made structures with unusual electromagnetic properties not seen in nature—commonly known as “metamaterials”—has generated much interest in designing filters, antennas, lenses, and other devices based on negative values of permittivity (ε) and permeability (μ). Manipulating negative values of these electromagnetic parameters has found applications in communication technology and cloaking research by taking advantage of interesting phenomena such as a negative index of refraction and the reverse Doppler Effect. RF and microwave filters with different frequency responses (low-pass, high-pass, band-pass, and band-stop) can be realized by varying microstrip signal line shapes at a frequency of interest due to the fact that the metamaterial frequency response is dependent on the physical dimensions of the structures. For example, the center frequency of a filter can be determined by adjusting the physical dimensions of metamaterial building blocks called split-ring resonators (SRR) or their duals, complementary split-ring resonators (CSRR). To further metamaterial applications, however, non-planar surfaces and effects of curvature on frequency response must also be considered. In this work, an RF metamaterial filter is presented to demonstrate an improvement in the band-pass frequency response from a previous design at Auburn University by enhancing the upper band behavior of the filter. This is achieved by modifying the metamaterial design on the microstrip device to incorporate new additions to the signal line to combine both high-pass and low-pass metamaterial design concepts, resulting in a band-pass response. The filter is designed using a liquid crystal polymer (LCP) slab as a substrate due in part to its dielectric properties, but also to investigate the filter's performance on a flexible structure. An exploration into the roles of different signal line and CSRR dimensions in filter design is given, and a microstrip filter designed using ANSYS HFSS is shown along with simulation results to verify band-pass filter response. LCP was selected due to its excellent RF properties, its resistance to moisture absorption, and its ability to be micromachined.
A Module-on-module Manufacturing Process and the Study of its Warpage and Signal Integrity
Authors: Wang Thomas , Lin James , Cheng Tony , Hong Ping-Chi , Lin Albert , Chang Harrison
Published: October 2015

This paper describes a package design and associated manufacturing assembly process that stack a module on top of another module using a frame board. The module on the top could be in molded or open frame form. In addition, this manufacturing process is compatible with the conformal shielding process important in RF applications. The complete module-on-module can be coated seamlessly and connected to the ground planes of the two substrates.

The module may be a part of product line that requires more functionality over the same foot print. There is the need to houses more components than its predecessor. Such example includes the standard memory package-on-package. However, if the module on top is not of commodity type, or when the volume is not big enough to develop a standard package, this module-on-module architecture and process could be a good solution. Alternatively, one could fix the design of bottom module , and design multiple choices of the top module. When stacked together, the two modules form various different configurations in order to serve different functionalities.

The structure of the module on module is shown in figure 1 below:

Figure 1 Structure of the Module on Module

On the frame board, there are vertical via where vertical electrical and power connection can be made. The frame board is mounted on the main board-II by surface mount process with underfill option. In the figure, a molded module on the top is shown, and an overall coating is applied to the whole module-on-module.

Figure 2 Manufacturing Process of the Module-on-module

The assembly process of the module-on-module is shown in Figure 2. First, the bottom module is manufactured by a one side SMT process and sawed, with the frame board soldered and underfilled. Then, the top module is SMT and molded in a panel form on the one side, and the bottom module is SMT and underfilled on the other side. Last, the complete module is sawed and conformal shielded by the sputtering process. The design of the ground plans of the substrates, together with that of the frame board, makes it such that the coating is connected to the ground planes of the boards.

It is important to study the warpage of such a module-on-module to make sure that it meets the JDEC standards. It is important to assure that the signal integrity of the electrical connections, including RF connections, inside of the frame board meets the requirement. Both simulation and measurement are made to test vehicles of the module-on-module. It is found that the simulation matches the measurement nicely. This module structure can be used for a variety of applications.
Ultralow Residue (ULR) Semiconductor Grade Fluxes for Flip-Chip and MEMs Applications
Authors: Durham Maria , Lim SzePei , Chou Jason , Mackie Andy
Published: October 2015

Copper pillars topped with solder microbumps are emerging as a standard flip-chip solder bump replacement in the semiconductor assembly industry. The relentless drive towards finer pitch, combined with reduced copper pillar height, makes aqueous cleaning of flip-chip flux residues more difficult. An emergent failure mode is joint damage and subsequent yield loss during aqueous jet impingement.

The move towards semiconductor grade ultralow residue no-clean fluxes and away from cleaning processes is therefore inevitable for both flip-chip and MEMS applications to meet industry roadmap challenges. The low residue also optimizes underfill adhesion and decreases possible outgassing during underfill cure. This paper discusses the variety of new and emerging failure modes for new packing processes using thinned die with copper-pillar/microbumps. The testing of assembly materials for this purpose will also be discussed.
A Microcontroller Approach to Measuring Transmissibility of MEMS Devices
Authors: Li Chong , Wu Yixuan , Yang Haoyue , Jenkins Luke L. , Dean Robert N. , Flowers George T.
Published: October 2015

The transmissibility reveals two very useful characteristics of a micro-electro-mechanical systems (MEMS) device, the resonant frequency and the mechanical quality factor. Real time knowledge on these two important factors can enhance application performance or avoid potential problems from environmental disturbances due to fabrication tolerances and the resulting operational differences in otherwise identical devices. Expensive laboratory equipment is typically used to measure the transmissibility. However, these test systems are not readily adaptable to field use. Therefore, it is important to be able to measure the transmissibility using a real time technique with a simplified test setup. This study proposes a technique that can compute the transmissibility in real time using a low cost microcontroller.

This technique utilizes two laser vibrometers to detect the input and output motions of the proof mass in a MEMS device, which are fed to high speed 500 KHz analog to digital converters (ADC) in the microcontroller. A filtering step is performed to decrease noise. After the sampling and pre-filtering, a Fast Fourier Transform (FFT) is performed to convert the time-domain signals to frequency domain signals. The amplitude of the output signal at each frequency is divided by the amplitude of the corresponding input signal at each frequency to obtain the transmissibility. To overcome the difficulties resulting from measurement and quantization noise, a recursive calculating algorithm and a de-quantization filter are introduced. The recursive calculating process guarantees that the system updates the results continually, which results in a transmissibility plot covering the entire bandwidth. The de-quantization filter considers the validity of the data and performs the transmissibility division step accordingly.

A cantilevered structure was chosen as the device-under-test to verify and evaluate this technique. The cantilevered device was attached to an electromechanical shaker system for vibratory stimulation. Two laser vibrometers were used to detect the input and output motion and this data was fed into a microcontroller. The microcontroller was STM32F407, which is 32-bit and 168 MHz controller. The tests demonstrated that this technique can measure the transmissibility and therefore the resonant frequency and mechanical quality factor accurately compared to a professional signal analyzer.
Bio-inspired Functional Materials Converted from Nature Species
Authors: Zhang Di , Liu Qinglei , Zhang Wang , Zhu Shenming , Su Huilan , Gu Jiajun , Fan Tongxiang , Ding Jian , Guo Qixin
Published: October 2015

Biological materials naturally display an astonishing variety of sophisticated nanostructures that are difficult to obtain even with the most technologically advanced synthetic methodologies. Inspired from nature materials with hierarchical structures, many functional materials are developed based on the templating synthesis method. This review will introduce the way to fabricate novel functional materials based on nature bio-structures with a great diversity of morphologies, in State Key Lab of Metal Matrix Composites, Shanghai Jiao Tong University in near five years. We focused on replicating the morphological characteristics and the functionality of a biological species (e.g. wood, agriculture castoff, butterfly wings). We change their original components into our desired materials with original morphologies faithfully kept. Properties of the obtained materials are studied in details. Based on these results, we discuss the possibility of using these materials in photonic control, solar cells, electromagnetic shielding, energy harvesting, and gas sensitive devices, et al. In addition, the fabrication method could be applied to other nature substrate template and inorganic systems that could eventually lead to the production of optical, magnetic, or electric devices or components as building blocks for nanoelectronic, magnetic, or photonic integrated systems. These bio-inspired functional materials with improved performance characteristics are becoming increasing important, which will have great values on the development on structural function materials in the near future.
The Future of Maximum CAD/CAM Automation for Ceramic Hybrids
Authors: Sovinsky John , Sylvester Geoff
Published: October 2015

New concepts developed maximize CAD/CAM automation for all types of Ceramic Hybrids including Thick Film, Thin Film, LTCC and HTCC. Designs can go quickly from concept to manufactured product, which will fuel more progress to bring a largely manual process to maximum automation, to include automatic masks, panels and generation of 3D analysis models. Maximum automation results in expanded use of technologies that are now shrinking. Technologies that have complex and difficult to understand design and manufacturing steps have a hard time gaining wide acceptance.

CDS is tackling this complex challenge and is designing and implementing the following processes to solve the most difficult CAD/CAM problems:1. Be a true CAM tool that reads in designs from any other EDA (layout) system. Y2. Run all possible DRC checks necessary for high fabrication and assembly yield. Y3. Make all manufacturing masks automatically from very basic designs by using settings in an automatically configurable table. Y4. Panelize all types of Ceramic designs in preparation for manufacturing. Y5. Generate documentation automatically through from stored configuration files. D6. In LTCC and HTCC, place cavity punches (nibbles and rubs) automatically and feed correct machine data to the punch machine. Y7. Export resistor trimming data directly to the laser trimming machine. F8. Feed flying probe test data directly to the flying probe tester. D9. Automatically make a 3D Image and export ACIS or STEP for thermal analysis. D10. Export data directly to all electrical analysis and thermal analysis tools. P11. Support circuit fabrication non-planar surfaces. F12. Make full 3D analysis models of circuits non-planar surfaces. FThe purpose of this paper is to define what is required for the Ceramic Hybrid industry to realize full automation in design, checking and output to manufacturing. Your ideas are welcome.
New Perovskite Nanomaterials and Their Integrations into High-k Dielectrics
Authors: Osada Minoru , Sasaki Takayoshi
Published: October 2015

We report on a bottom-up manufacturing for high-k dielectric films using a novel nanomaterial, namely, a perovskite nanosheet (LaNb2O7) derived from a layered perovskite by exfoliation. Solution-based layer-by-layer assembly of perovskite nanosheets is effective for room-temperature fabrication of high-k nanocapacitors, which are directly assembled on a SrRuO3 bottom electrode with an atomically sharp interface. These nanocapacitors exhibit high dielectric constants (k > 50) for thickness down to 5 nm while eliminating problems resulting from the size effect. We also investigate dielectric properties of perovskite nanosheets with different compositions (LaNb2O7, La0.95Eu0.05Nb2O7, and Eu0.56Ta2O7) in order to study the influence of A- and B-site modifications on dielectric properties.
Electroless Nickel and Au Plated Silver LTCC Solution for Advanced Hermetic Packages
Authors: Ross David , Mitchell Greg , Draney Nathan , Gay Simon , Curley Michael
Published: October 2015

Low Temperature Cofired Ceramics (LTCC) for military and medical applications requires high reliability interconnects that have been traditionally met using cermet Au metallization But due to the rising cost of Au, it has become cost prohibitive in some applications to tier 1 defense contractors. The utilization of Silver cermet metallization reduces the costs of LTCC up to 50%, however requires proper coverage using either a Mixed Metal, or a Nickel (Ni) and Au (Au) Plated surface. Efforts to date on mixed metal solutions with resistive PdAg or PtAg transitions without Kirkendahl voiding have been unreliable for systems requiring post fire metallizations due to voiding at the silver to Au transition. Anaren Ceramics has developed an all Silver LTCC solution that utilizes Electroless Ni and Au (ENiG) plating, lowering the cost of entry for LTCC users up to 50%.

Anaren Ceramics has developed a proprietary plating process for the DuPont 951 LTCC [1] tape material and silver metallization which meet the needs of high reliability, high cavity count LTCC packages that are fully solderable using PbSn, or AuSn materials for hermetic applications. The Anaren Ceramics solution meets Mil Std 883 test requirements and this paper will discuss the test results for plated LTCC substrates and AuSn brazed LTCC assemblies that include 350°C Bake Test, Tape Peel, X Ray Inspection, Open Header Leak Rate, Moisture under Bias, Salt Atmosphere, Die Shear, and Wire Bond.
Evaluation of Direct Bond Aluminum Substrates for Power Electronic Applications in Extreme Environments
Authors: Patterson Brian , Kulkarni Srikanth , Elshabini Aicha , Barlow Fred
Published: October 2015

Power packages that require large current capacities typically employ some form of thick conductive traces attached to a thermally conductive ceramic material to create a suitable package substrate. The most common substrate currently used in high power applications is Direct Bonded Copper (DBC). Though this is a well established, reliable, and commonly used substrate, DBC suffers from poor long term mechanical reliability when exposed to extreme temperature excursions. In an attempt to improve on this technology, substrate materials such as Active Metal Bond / Braze (AMB) and Direct Bonded Aluminum (DBA) are being investigated.

Previous work has shown that the accelerated aging / thermal shock lifetimes of DBC and AMB are significantly shorter than that of DBA substrates. Though DBA substrates last longer, they still have some issues that require attention before it can be accepted as an improved alternative to DBC substrates in these types of applications. The main issues that have been observed are DBA's increase in surface roughness during aging and aluminum's poor solderability when compared to copper or nickel.

The emphasis of this paper is to investigate the dramatic increase in DBA's surface roughness and its' possible causes due to thermal cycling as well as present a thermal cycling lifetime comparison of the three different substrate. To evaluate this, a DBA sample with one side raw aluminum and one side electroless nickel plated (high phosphorous) was thermally shocked from −40°C to 200°C with surface roughness measurements preformed every 300 cycles. Another batch of samples was thermally shocked to 6000 cycles and lifetimes were compared. One nickel plated DBA sample shocked to 4000 cycles was cross-sectioned and analyzed with SEM and EDAX to evaluate any changes in the metal. The grain structure of a thermally cycled sample was also examined with a Scanning Electron Microscope (SEM).
Interfacial reaction of LTCC/NiCuZn ferrites in multilayer composites
Authors: Hsiang Hsing-I , Lyu Bing Jyun , Tsai Chi-Yao , Mei Li-Then
Published: October 2015

In this study, the cofiring behavior and interfacial interaction between a low dielectric constant LTCC material and NiCuZn ferrites at 900°C were studied using XRD, dilatometer, SEM, EPMA and TEM. It was observed that the delamination occurred at the interface between LTCC and NiCuZn ferrites added with Bi2O3. It may be due to the Bi enriched at the interface and diffused into LTCC, which shifted the densification curve of LTCC towards low temperature, and hence resulted in the shrinkage mismatch between LTCC and NiCuZn ferrites.
A Novel Low-Temperature-Fired Multifunctional Varistor-Magnetic Ferrite Materials
Authors: Mei Li-Then , Hsiang Hsing-I , Ye Hui-Wen
Published: October 2015

A novel low temperature-fired (950°C) multifunctional varistor-magnetic ferrite materials can be obtained by adding V2O5 into CuCr0.2Fe1.8O4 ferrites. The relationship between the grain-boundary composition and varistor properties were investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersion spectroscopy (EDS), and X-ray photoelectric spectroscopy (XPS). The addition of V2O5 can effectively reduce the sintering temperature of CuCr0.2Fe1.8O4 ferrites to temperatures of lower than 950°C. Moreover, the V5+ ions occupied the octahedral site of spinel structure and acted as donor dopant, which resulted in the semiconductive grain. The copper-rich observation at the grain boundary based on the TEM and EDS results implied that copper oxide would possibly develop at the grain boundary as the acceptor state, forming double Schottky barriers with the n-type semiconductor grains.
Inkjet Printing as Technology for In-Situ Blending of Thick-Film Resistor Inks
Authors: Waßmer Marcel , Diel Waldemar , Krüger Klaus
Published: October 2015

The integration of passive components directly into circuit boards is an efficient alternative to surface mounted devices. Digital printing methods are more and more emerging technologies for the fabrication of microelectronic circuits. Inkjet printing is a technology for the deposition of a variety of particles with the unique selling proposition of in-situ ink blending.

Resistors are one of the most frequently required passive components in electronic circuits. In LTCC technology the integration and additionally the embedding of resistors promises new applications. Integrated resistors are usually screen printed. Inkjet printing has several advantages to compete seriously with screen printing as production method. This study investigates the opportunities of in-situ blending in inkjet printing of thick-film resistors. In a first step, the different options of ink blending are analyzed theoretically. In order to have a basis for further calculations five compositions with a wide resistivity range are printed purely. Afterwards the printed resistors are passed through a post-fire process and the electrical properties are recorded. Reliability and long term stability in drop formation are fundamental for production process.

In a second step, the different options of ink blending are analyzed. The five compositions are blended to four combinations of neighbouring inks and are printed and blended with two inkjet printheads. The effect of blending is characterized towards the change in electrical behaviour and the different blending techniques are compared. Additionally, the opportunity of layer thickness variations is investigated and its influence is analyzed. Further, the influences of printing conditions on morphology and resistivity are discussed.
Micro Fluidic Mass Flow Sensor Concept for Functional Ceramic Circuits
Authors: Zeilmann C. , Haas T. , Backes A. , Schmid U.
Published: October 2015

Low temperature co-fired ceramics (LTCC) is established as a widespread platform for advanced functional ceramic circuits in many different applications, such as space, aviation, medical and sensor technology. MLC (Multi Layer Ceramics) based systems allows integrating passive components which leads to a high integration level. For micro fluidic devices the integration of 3D structures like channels and chambers are necessary. Using LTCC is predestined to integrate sensor elements due to the high reliability qualities, the good characteristics of the ceramic as well as the excellent physical properties. To realize 3D micro channels not only in lab status adequate manufacturing processes are mandatory. This study proposes the realization of micro fluidic channels and show in which ways these can be realized by a range of new developed manufacturing methods during the LTCC process. A benchmark of 3D laser structuring and two cold embossing technologies were investigated to show the benefits and also the limits of each technology. The sensor elements, which were directly integrated into the LTCC body, are based on PTC and resistor materials realized in thick film technology. The excellent performance of a micro fluidic LTCC system will be shown based on a manufactured demonstrator. The final conclusion is, that these established manufacturing and integration methods offer a remarkable potential to meet the requirements for future circuit designs, where actual design concepts cannot solve all issues satisfying, in particular where harsh environmental conditions occur or a high integration concept is mandatory.
Development and characterization of glass matrix composites as porous coating film of a solid state reference electrode
Authors: Feller Claudia , Furche Stefan , Eberstein Markus
Published: October 2015

For protection against leaching of the electrolyte reservoir of a solid state reference electrode a porous covering film was prepared and characterized. The porous covering film is based on a glass matrix composite and fired at 400 °C according to the thick-film-based structure of the reference electrode. Based on stability investigations on low sintering glasses in the range of pH 1.68 to pH 9.18 and in various concentrated potassium chloride solutions, a suitable zinc borate glass was selected. Using this glass and Al2O3 or ZrO2 oxide powders, various glass matrix composites were prepared and their sintering behavior was investigated in dependence on the amount of crystalline fraction up to 45 vol%. The shrinkage was measured by heating microscopy of powder compacts of cylindrical shape. In addition composite films on ZrO2 substrates screen-printed and at 400 °C fired were characterized in terms of their porosity by means of micro structural analysis and electrochemical deposition of copper. According to these investigations, suitable composites were selected as porous covering materials for the reference electrode and were tested therefore. The electrochemical characterization showed that the solid-state reference electrodes with porous covering films have a very good performance compared to conventional reference electrodes.
Recent progress in the shaping and sintering of barium titanate nanoparticles. Application to high permittivity capacitors
Authors: Guillemet-Fritsch Sophie , Voisin Christophe , Quintero Roman Nava , Dufour Pascal , Tenailleau Christophe , Garib Juan Antonio Aguilar , Melo Martin Edgar Reyes , Durand Bernard
Published: October 2015

The miniaturisation of electronic components required for many devices involves an increase their volumic efficiency. This work focus on the size reduction of capacitors. They are two ways for increasing the capacity of such passive components. One is to find materials with high permittivity, the other is to reduce the thickness of the films used in multilayers ceramics.

Barium titanate, BaTiO3 (BT) nanoparticles were sintered using Spark Plasma Sintering (SPS) because the material presents interesting properties when obtained by SPS [1–3]. In this case, very unusual interesting dielectric properties, a so called “colossal” permittivity value up to several thousands. Moreover, no temperature dependence is observed. However, the values of dielectric losses are too high to consider industrial applications. In order to reduce these dielectric losses, different approaches have been proposed to control the chemistry of grain boundaries. We present here the structural, microstructural and electrical properties of ceramics sintered by SPS from BaTiO3 powders elaborated by co-precipitation method. Different routes tested to improve the dielectric properties of the ceramics are presented and discussed.

On the other side, thick films of BT have been prepared. The objective of this work was to develop a BaTiO3 material having an accurate particle size to reduce the thickness of sintered films down to 1 μm. The rheological properties of the slurry have been optimized and, thanks to a suitable tape casting process, homogeneous thin films of 1 μm thickness could be obtained. Some properties of the films are described.
Realisation of Large Cavities in Multilayer Ceramics by Cold Low Pressure Lamination and Their Characterisation by μCT
Authors: Deisinger Ulrike , Fey Tobias , Roosen Andreas
Published: October 2015

In microelectronics the ceramic multilayer technology is frequently used as it allows a precise and yet flexible production of MEMS, microelectronic devices, micro reactors or devices for micro fluidics. During production of those multilayer structures the single layers are typically laminated by thermo-compression. However, large cavities cannot be realised using thermo-compression without adding sacrificial fillings. In contrast, the cold low pressure lamination (CLPL) technique allows lamination at room temperature without applying a high pressure. As in this lamination technique no mass flow occurs, internal cavities are not destroyed during the lamination step.

In this study, commercially available LTCC green tapes were structured using a milling plotter with a high frequency spindle. Different process parameters (milling speed, spindle frequency) were evaluated regarding the accuracy of shape and quality of the channel edge. Channels with various dimensions (2.5 - 15 mm width and 30 mm length) were milled into the green tapes. Subsequently, the green tapes were laminated using the CLPL technique. With CLPL adjacent ceramic green tapes are joined by a double sided adhesive tape, which is applied by a soft roller. By alternately applying green (structured or unstructured) and adhesive tapes multilayer structures with internal cavities are formed. For characterisation of the sintered LTCC structures μCT (computed tomography) was used to analyse the internal structure without destroying the sample. Influence of sintering regime on deformation was evaluated. It was shown that milling of green tapes in combination with CLPL is a suitable method to fabricate internal cavities in LTCC multilayer structures.
Flexography Printing of Silver Tracks on LTCC Tapes – Effect of Printing Direction on Line Properties
Authors: Faddoul Rita , Reverdy-Bruas Nadège , Blayo Anne , Chaussy Didier
Published: October 2015

The originality of this work is to print with flexography process conductive silver lines suitable for Low Temperature Co-fired Ceramics (LTCC) multilayer systems. Screen printing conductive paste with 65% silver flake particles was optimised for flexography process. Patterns with different line widths – from 100 to 600 μm – were printed in two directions, parallel and perpendicular to printing orientation. Printed lines withstood temperature as high as 875°C for one hour, relative to conventional sintering profile of LTCC multilayer systems. Line width, thickness and roughness decreased after sintering. A minimum line width of 153 μm was measured on sintered lines. Line thickness varied from 1.8 to 3.8 μm and line roughness from 0.7 to 0.9 μm after sintering. Conductive silver lines along 34 cm length were accomplished after sintering. Very low values of electrical resistivity were measured on the sintered lines. This study demonstrates the huge potential of flexography printing for LTCC multilayer systems.
Chemical selective coating of nickel / palladium / gold metallization on screen-printed thick film on LTCC and Al2O3 ceramic for high temperature applications
Authors: Müller Jens , Mache Thomas , Thelemann Torsten
Published: October 2015

Electroless plating on silver is a low cost alternative to printing of mixed metals or pure gold paste systems on LTCC. It overcomes the necessity to have material transitions from inner to outer layers or from conductor lines to wire bonding- or solder-pads.

Since no commercial process and material set for silver thick film conductors has been available on the market a proprietary Ni/Pd/Au coating technology was developed for the use on silver inks for LTCC and Al2O3-ceramic as a base for both soldering and wire bonding.

The work included the screening of different chemicals as well as several silver paste systems from two commercial vendors. Conductor adhesion, plating layer thicknesses, plating accuracy, (lead free) solderability and gold wire-bondability were assessed to optimize the process.

Layers of about 5 microns Ni, (0.1 to 0.3) microns Pd and (0.05 to 0.15) microns Au were electrolessly deposited. The developed Ni-Pd-Au finish is an economical alternative with only about a quarter of the cost compared to the conventional use of silver, silver / palladium and gold compounds for ceramic substrates. This technology allows coating of the structures down to a fine pad size of 200×200 microns and a minimum line width of 100 microns, without reducing the adhesion mechanism between thick-film metallization and ceramic substrate.

By covering of pure conductors with high temperature glass or dielectrics, further material saving is possible. Besides, the process offers also very good coating of structures in cavities.
Effect of internal silver conductor on heat spreading capability of LTCC membrane
Authors: Reinlein Claudia , Türke Sascha , Gutzeit Nam , Müller Jens , Peschel Thomas , Burkhardt Thomas , Beckert Erik , Tünnermann Andreas
Published: October 2015

LTCC membranes are used as substrates of screen printed unimorph deformable mirrors. A high piezoelectric stroke is attributed to thin substrate materials. The application of deformable mirrors with high laser loads calls for a large heat spreading capability of the deformable unimorph mirrors. A large heat spreading capability is attributed to high thermal conductivity of the materials that is not allocated by LTCC. The present paper reports on the effect of internal silver conductor (DuPont 6145) on the heat spreading capability of the LTCC membrane.

Therefore, internal silver conductor is applicated into a 570 μm thin membrane on a diameter of 49.8 mm. The optical absorption of plain LTCC membranes and membranes with internal metallization is characterized by an Ulbricht sphere. Membranes with internal silver conductor and a reference sample without internal metallization (plain LTCC) are loaded with a laser beam. The absorbed laser power heats the LTCC membrane. We investigate the temperature increase upon one-Watt laser loading and prove a 37% lower setting maximum temperature (Tmax) for membranes with internal silver conductor compared to plain LTCC membranes. The characteristics of temperature over time are similar to the charging of a capacitor. The time constant for the internally metallized and plain LTCC membrane at same peak temperatures are similar. These results show the potential of internal silver conductor to increase the heat spreading capability of LTCC membranes.
Infrared Optical and Mechanical Properties of Ceramic Coatings Fabricated by Aerosol Deposition
Authors: TSUDA Hiroki , AKEDO Jun , HIROSE Shingo , OHASHI Keishi
Published: October 2015

The possibility and mechanical improvement of the infrared ceramic coatings fabricated on fluoride substrates at room temperature by aerosol deposition (AD) were investigated aiming to optical components for infrared applications and devices. The yttria coating possibility fabricated on barium fluoride substrates by the AD process was found by adjusting one of the deposition conditions. The optical and mechanical properties of the fabricated ceramic coatings, which are important in practical applications, were evaluated by transmittance and hardness measurements respectively. The mechanical hardness of the fabricated yttria single coatings was increased to 4 times higher than that of the barium fluoride substrates. Furthermore, by an additional layer on a barium fluoride substrate, the mechanical properties of the fabricated multi-coatings including an upper yttria layer were improved from that of the single yttria coating on the barium fluoride substrate, retaining the IR transmittance of the single yttria coating at the wavelength of 10μm.
Novel High-g Accelerometer Geometry Requiring 90 Degree Contacting Techniques
Authors: Kuells Robert , Nau Siegfried , Salk Manfred , Thoma Klaus , Ihle Martin , Goldberg Adrian
Published: October 2015

This paper presents a novel silicon MEMS high-g accelerometer and its package solutions. It exhibits superior performance compared with commercially available transducers, but requires 90 degree contacting. It has a resonant frequency of more than 2.5 MHz, while having a sensitivity of about 0.2 μV/Vexc./g, which means a performance increase of about one magnitude over existing similar sensors. These high values are due to its unusual geometry, which causes the sensing direction to lie in the wafer plane. This means that the sensor can only be used to its full abilities, when 90 degree contacting is applied. Three solutions are presented that solve this problem on different levels, i.e. on cable, package and die level. They are based upon a machined bulk alumina ceramic, a thick nine layer LTCC ceramic and a non-contact direct write technique called aerosol printing, respectively. The latter, which works at the lowest, i.e. die, level, promises the best characteristics regarding size, cost and measurement performance.
Stress Assisted Grain Growth and Dielectric Properties of BaLa4Ti4O15 Thick Films
Authors: Amaral L. , Senos A.M.R. , Jamin C. , Guillon O. , Vilarinho P.M.
Published: October 2015

Thick films of BaLa4Ti4O15 (BLT) are potential candidates for applications in telecommunications devices, operating at microwave frequencies, in which miniaturization is required. The production of thick films usually involves the powder deposition on top of a dense substrate, followed by the constrained sintering of the powder layer. Constrained sintering of functional complex oxides as BLT has not been addressed. In this work we demonstrated that in opposition to isotropic constrained sintering model predictions, BLT films with density equivalent to freely sintered bulk samples were obtained after 180 min at 1500 ºC. Another unexpected observation is that films showed a larger grain size than the bulk sample sintered under the same conditions. A high degree of anisotropy was detected in grain's shape, with high aspect ratio, and in film's orientation, with grains oriented parallel to the substrate. In comparison, in freely sintered bulk sample, lower aspect ratio and lower grain orientation are observed. Stress assisted grain growth is shown to be responsible for the increased grain growth and high texturization observed in the films. Dielectric characterization was also performed in films and bulk and the electrical response correlated with the microstructural features. Both showed near-zero temperature coefficients of permittivity, revealing a dielectric response with great temperature stability, interesting for microelectronic applications.
Piezoelectric and Dielectric Enhancement of New Nano-structured Ceramics with Heteroepitaxial Interfaces
Authors: Wada Satoshi , Yamashita Kenta , Kawashima Hideto , Fujii Ichiro , Ueno Shintaro , Nakashima Kouichi , Kumada Nobuhiro , Moriyoshi Chikako , Kuroiwa Yoshihiro , Fujikawa Yoshinori , Tanaka Daisuke , Furukawa Masahito
Published: October 2015

Barium titanate (BT) - potassium niobate (KN) nano-structured ceramics with an artificial morphotropic phase boundary (MPB) structure were prepared by a solvothermal method at temperatures below 230 °C. Various characterizations of the BT-KN nano-structured ceramics revealed that the BT/KN molar ratio was 1, the porosity was around 30 %, and the interface between BT particles and KN crystals was heteroepitaxial. The apparent piezoelectric constant d33* was 136 pC/N, which was three times larger than that of 0.5BT-0.5KN dense composite ceramics. The concept proposed in this study can be useful to create piezoelectric ceramics with artificial MPB regions.
Interfacial effects in magnetoelectric thin/thick composite films
Authors: Zhou Yuan , Park Chee-Sung , Murayama Mitsuhiro , Priya Shashank
Published: October 2015

This study reports the effect of interfacial structure on the magnetoelectric and ferroelectric characteristics in magnetoelectric laminate thin/thick films. Both bilayer and trilayer magnetoelectric heterostructures were deposited on a Pt/Ti/SiO2/Si substrate using pulsed laser deposition (PLD) and sol-gel deposition (SGD) respectively. BaTiO3 [BTO] / Pb(Zr0.6Ti0.4)O3 [PZT] and CoFe2O4 [CFO] were used as piezoelectric and magnetostrictive materials. The interface between CFO/PZT and CFO/BTO films was found to exhibit excellent interface without any cracks or delamination. PLD grown BTO on CFO was found to exhibit the columnar structure. SG deposited PZT/CFO/PZT tri-layer structure exhibited granular structure with high density. Ferroelectric and magnetoelectric coefficient of as-grown films was investigated to understand the effect of interface characteristics. Good ME coupling for the trilayer structure provided important insight about the nature of elastic strain coupling.
Evaluation of TFR-Characteristics in aWide Temperature Range
Authors: Partsch Uwe , Lenz Christian , Wenzel Marco , Eberstein Markus
Published: October 2015

Thick-Film Resistors (TFR) are applied for many years for the manufacturing of ceramic electronic packages as well as for mechanical or thermal sensors. The resistors characteristics (e.g. Rsqr, HTCR, CTCR) are guaranteed by paste suppliers for a thermal range of operation between −55 and 125°C. However, specific sensor applications require higher operation temperatures of up to 500°C.

In the paper the results of the characterization of commercial TFR at elevated temperatures on alumina substrates are presented. Electrical characteristics (e.g. Rsqr, HTCR, CTCR, GF) are correlated with materials characteristics (TFR thermal expansion, glass transition temperature, microstructure). Different requirements are discussed regarding an improved high temperature applicability of TFR. Advantages and limits of the commercial TFR will be presented.
Strain Measurement and Mechanical Property Evolution in Sol-Gel PZT Thin Films
Authors: Berfield T.A. , Hoang T. , Porter D.A. , Meuris B.J.
Published: October 2015

Cracking is a notorious issue with sol-gel PZT thin films, and film failure in this manner is difficult to reliably predict due to constantly evolving mechanical properties. In this work, two non-contact experimental methods are used to quantify the stiffness response of PZT sol-gel during thermal loading and the influence of solution additives, such as lactic acid and gycerol. The mechanical properties are determined using a digital image correlation method to measure strain and wafer curvature measurements to estimate bi-axial stress. Results show the transition from a compliant response to more glassy behavior. The importance of this changing stiffness is shown for a specific application of a buckled MEMS actuator and in relation to adhesion based failure modes.
Multifunctional LTCC Substrates for Thermal Actuation of Tunable Micro-Lenses Made of Aluminum Nitride Membranes
Authors: Leopold S. , Geiling T. , Fliegner C. , Pätz D. , Sinzinger S. , Müller J. , Hoffmann M.
Published: October 2015

Thin membranes are widely used for tunable micro-lenses, where the membrane, usually made from polymers, defines the surface of a subjacent liquid. If the liquid is pressurized, the membrane deflects and forms a lens. In many cases, a macroscopic pump is used to generate the pressure. Here, we use a multifunctional LTCC substrate, which consists of two cavities. A micro-fluidic network allows their independent filling. For the actuation, the actuating cavity is filled with air and the optical cavity is filled with immersion oil. If the actuating cavity is heated by screen-printed resistors, the fluid expands and a pressure is transmitted to the optical cavity via a micro-fluidic channel. The optical cavity is covered with a glass chip and a membrane chip, respectively. We use 500 nm thick membranes of aluminum nitride (AlN), which have a 3 mm diameter and are fabricated using technologies of silicon based micro-electro-mechanical systems. With 6 W electrical heating power a temperature increase of 100 K within the actuating cavity is achieved. The generated pressure causes a membrane deflection in the optical cavity of about 30 μm. The thermal actuation is investigated using thermal imaging. By heating the actuating cavity, the optical cavity also heats up, but no temperature gradients along the silicon chip is found. Optical experiments show the imaging capability of the lens and confirm a tunable refractive power of 0..17 dpt.
Modeling the Failure Mechanism of Electrical Vias Manufactured in Thick-Film Technology
Authors: Ortolino Dominique , Kita Jaroslaw , Moos Ralf , Wurm Roland , Pletsch Andreas , Beart Karin
Published: October 2015

Hybrid-thick-film circuits consist of many different components, like screen-printed passive elements (conductors, resistors, and electrical vias), SMDs, and active elements like transistors or ICs. Whereas most of passive components are well investigated and described, the electrical vias often remain unattended. Resistive heating caused by high current pulses might lead to the destruction of the vias. In previous work, we set up a 3d FEM model and investigated the influence of non-radial-symmetric contacting and geometric irregularities of the vias on the occurring maximum temperatures.

The present contribution deals with the modeling of a failure mechanism of an electrical via caused by high current pulses. When the local temperature exceeds a defined melting temperature, the metallization layer melts and is not available for conduction any more. The current density rises as a consequence of the decreased cross section area of the vias and leads to a higher heat production in a smaller area. This conducts further melting of the metallization layer and results in a positive feedback that accelerates the destruction of the via. The approach of this contribution is to model the described failure mechanism in a 2d-radial-symmetric FEM model.

The modeling results were validated using high current measurements of electrical vias. Modeling and measurement of the voltage drop during a constant current pulse agree very well, from very low current density pulses up to pulses that lead to the destruction of the vias.
Complex Superstructures Resulting from Compositional Modulation and Octahedral Tilt Twinning in AA′BB′O6 Doubly Cation Ordered Perovskites
Authors: King Graham , Garcia-Martin Susana , Urones-Garrote Esteban , Nenert Gwilherm , Woodward Patrick M.
Published: October 2015

The ordering of cations within the perovskite structure can have a profound effect on the physical properties. A number of AA′BB′O6 perovskite phases which have both a rock salt ordering of the B/B′ cations and a layered ordering of the A/A′ cations have recently been prepared and studied. In some of these compositions complex nanoscale superstructure formation has been observed. These superstructures are the result of compositional modulations involving the occupancies of the A and A′ cations and are accompanied by a twinning of the octahedral tilt system. A wide variety of patterns are observed, such as 1-dimensional stripes or 2-dimensional chessboards which can have periodicities which are either commensurate or incommensurate with the underlying subcell. These superstructures cannot be easily detected by powder X-ray diffraction but have been observed using a combination of high resolution transmission electron microscopy, electron diffraction, and neutron powder diffraction. The factors which determine the dimensionality and periodicity of the superstructures are discussed and compared with the closely related Li based perovskite systems.
Laser structuring of printed layers on thick film ceramic substrates
Authors: Scheubeck R. , Gruebl W. , Pletsch A. , Schiller U. , Wurm R.
Published: October 2015

The market for automatic transmissions continues to grow. In addition to what originally attracted interest to the product – enhanced driver convenience – the prospect of greater fuel efficiency is now a further factor in their favor. Continental has been offering transmission control units (TCU) since 1982, starting with those for simple three-gear conventional automatic transmissions, followed by all-wheel applications in 1985, CVT applications in 1999, truck applications in 2000, and arriving at the double clutch transmissions in widespread use today. At present Continental Business Unit Transmission is technology leader worldwide in the market for transmission controls for the full spectrum of automatic drives. Continental TCU's are divided in “Stand alone”, “Attached to” and “Integrated” TCU's. However the “Stand alone” and “Attached to” TCU's are normally equipped with standard PCB substrates. Because of the highest requirements in temperature, vibration and typical medias (aggressive Transmission oils – liquid & gaseous), standard organic substrates cannot be used, ceramic substrates are typically preferred. A common technology in that case is the ceramic based thick film technology, where conductor and resistor pastes are printed on the surface of a ceramic alumina substrate by using a common screen printing process. The printed layers (Au, Ag, AgPd, AgPt) have to be dried and thermally sintered after appliance. The increasing functionality of the TCU's and the increasing requirements due to miniaturization inherently show that thickfilm technology, as applied in a standard printing process, is not possible to reach those requirements. Continental has developed a concept to realize higher miniaturization of the circuit boards. Therefore a innovative laser structuring process has been installed for the newest generations of TCU's in cooperation with a leading machine and system manufacturer. By using the laser structuring of conductor lines it allows Continental to increase the connection density by keeping the substrate size unchanged. Typical common printing pitches in thickfilm production are 300μm, however pitches of 100μm are possible by laser structuring in mass production.