bluuebunny/crossref_metadata_2025 huggingface dataset:
Problems and promises of sapphire micromachining
Authors: Ahmad Syed Sajid , Haring Fred
Published: October 2015

In this presentation, we will summarize the results of numerous attempts at optimizing the sapphire via drilling process. We compared different laser drilling schemes, drilling parameters and materials. We will also discuss our experience with general micromachining of sapphire to make patterns for passives, channels and conductive paths. We also will discuss applications of the processes developed.
Advanced Silicon Interposer for High density and High Integration Electronic Packages
Authors: KUMOCHI SATORU , Koiwa Sumio , Suzuki Kosuke , Fukuoka Yoshitaka
Published: October 2015

As electronic product becomes smaller and lighter with an increasing number of function← the demand for high density and high integration becomes stronger.

Interposers for system in package will became more and more important for advanced electronic systems.

Interposers will be needed more complicated structure for 2.5D , 3D package and MEMS, OEMEMS new heterogeneous package structure

Silicon interposers with through silicon vias (TSV) and back end of line (BEOL) wirring offer compelling benefits for 2.5D and 3D system integration; however, they are limited by high cost and high electrical loss. [1]

This paper presents the demonstration of Silicon Interposers with fine pitch through Silicon vias(TSV),with embedded passive device.

We have developed the TSV interposer with redistribution layers on both sides using MEMS technology, high aspect ratio deep etching technology and filled Cu plating with deep through holes for cost reduction and low electrical loss. The TSV interposer with 400μm thick high resistivity Si, obtained without backside processing use of carriers.

Excellent through via reliability was demonstrated, due to double side thick polymer insulator that buffers the stress created by CTE mismatch between glass, copper vias and copper traces, and TSV at 200μm pitch passed 1000 thermal cycles from −55°C to 125°C.

We have evaluated high frequency transmission characteristic of Si through hole by the measurement S21 parameter. Highly insulating TSV resulted in insertion loss of less than 1dB at 20GHz.

Thin film SiN capacitor as embedded passive device was built in surface of TSV interposer by via first and via last method. The capacitance and leakage current of capacitor was measured and compared with two types of fabrication method.
BGA Board Level Reliability Analysis & Optimization
Authors: Yeung Betty
Published: October 2015

The solder joint reliability of semiconductor package interconnects to printed circuit boards is critical for product durability. A dominant failure mode is solder fatigue due to the CTE mismatch between the BGA component and PCB at thermal cycling. However, it is well known that other factors can impact fatigue behavior and time to failure such as solder joint geometry, die geometry, solder system, etc. Finite element modeling (FEM) and simulation can play an integral role in providing deeper insight into the impact of these package parameters on the overall assembly. However, a major challenge of accurately modeling these systems includes simulation of multiple length scales from the package, substrate, and solder joints. The FEM approach addressing these can lead to reduced cycle time, accurate simulation, and improved package performance. In this work, the finite element modeling and simulation procedure is demonstrated for a BGA package at accelerated temperature cycling conditions. At the component level, key details regarding the properties and constituents of the BGA package mold compound and substrate are established by coupling measured experimental warpage data and finite element modeling. Comparison of simulated & Thermoire measurements shows excellent agreement at the package level, with warpage correlation achieved over the entire temperature range. At the assembly level, the truncated sphere model is used to arrive at precise solder joint profiles for accurate representation to tie the package to the board. The combined validated package-level results and solder joint profiles are employed towards a subsequent thermo-mechanical analysis of the full BGA assembly. The entire simulation procedure is demonstrated for a BGA design, where inelastic creep and reliability test data are compared. High strain regions in the solder joint array are shown to compare closely with regions of failure from experimental reliability test data. The validated FEM model allows for extrapolating to similar package conditions allowing faster design cycle time and less time consuming experimental work.
Enabling Requirements for High Volume Thermo compression Bonding
Authors: Strothmann Tom
Published: October 2015

The potential of Thermo compression Bonding (TCB) has been widely discussed for several years, but it has not previously achieved widespread production use. TCB has now begun the transition to an accepted high volume manufacturing technology driven primarily by the memory market, but with wider adoption close for non-memory applications. Several key factors have enabled this transition, including advanced TCB equipment with higher UPH for cost reduction and advanced methods of inline process control. The unique requirements of TCB demand absolute process control, simultaneous data logging capability for multiple key factors in the process and portability of the process between tools. This introduces a level of sophistication that has not previously been required for BE assembly processes. This presentation will review state of the art TCB technology and the fundamental equipment requirements to support the transition to HVM.
Design and Fabrication of a PCB MEMS Module With Integrated Switches and Sensor Suite
Authors: Liew Li-Anne , Boteler D. , Lin C.Y. , Marsiglia N. , Lee Y.C.
Published: October 2015

We demonstrate the feasibility of integrating Kapton-based MEMS capacitive switches and a sensor suite onto a printed circuit board (PCB) with minimal impact to existing manufacturing processes. Copper-cladded kapton laminates were bonded onto rigid PCB substrates with a BCB film spacer. The kapton was patterned using reactive ion etching to produce MEMS structures such as suspended membranes and flexures. Atomic layer deposited alumina coatings were applied as dielectric layers for the capacitive switches and tilt sensors/accelerometers. The copper cladding was also patterned by etching to function as electrical leads, resistors, and capacitive electrodes.

In this way, MEMS switches, tilt/acceleration sensors, temperature sensors, humidity sensors, and vacuum pressure sensors, were all fabricated monolithically onto a PCB in a single module. We describe the fabrication process, challenges and improvements to the process in particular in the bonding and etching of the kapton films. We also describe the design of the various sensors and switches and demonstrate their functionality.
Characterization of a Semiconductor Packaging System utilizing Through Glass Via (TGV) Technology
Authors: Mobley Tim , Keusseyan Roupen , LeClair Tim , Yamnitskiy Konstantin , Nocon Regi
Published: October 2015

Recent developments in hole formations in glass, metalizations in the holes, and glass to glass sealing are enabling a new generation of designs to achieve higher performance while leveraging a wafer level packaging approach for low cost packaging solutions. The need for optical transparency, smoother surfaces, hermetic vias, and a reliable platform for multiple semiconductors is growing in the areas of MEMS, Biometric Sensors, Medical, Life Sciences, and Micro Display packaging.

This paper will discuss the types of glass suitable for packaging needs, hole creation methods and key specifications required for through glass vias (TGV's). Creating redistribution layers (RDL) or circuit layers on both sides of large thin glass wafer poses several challenges, which this paper will discuss, as well as, performance and reliability of the circuit layers on TGV wafers or substrates. Additionally, there are glass-to-glass welding techniques that can be utilized in conjunction with TGV wafers with RDL, which provide ambient glass-to-glass attachments of lids and standoffs, which do not outgas during thermal cycle and allow the semiconductor devices to be attached first without having to reflow at lower temperatures. Fabrication challenges, reliability testing results, and performance of this semiconductor packaging system will be discussed in this paper.
Design of Filled One Step Chip Attach Materials (OSCA) for Conventional Mass Reflow Processing: Curing Kinetics and Solder Reflow Aspects
Authors: Duffy Daniel , Bhavsar Hemal , Xin Lin , Liu Jean , Tolla Bruno
Published: October 2015

One step chip attach materials (OSCA) are dispensable polymeric materials for flip chip assembly, which are designed to flux metallic interconnections and subsequently turn into an underfill upon curing. OSCA materials enable a drastic simplification of the assembly process by combining the reflow, flux residue cleaning and capillary underfilling steps used in traditional die attach processing into a single step. A key challenge when designing OSCA materials for conventional mass reflow processing (identified as OSCA-R) is timing the cure kinetics with the fluxing and soldering sequences during reflow processing. OSCA-R materials must also have a process-friendly rheological design that integrates seamlessly with standard dispensing equipment and enables the filler loading levels required for customized thermal conductivities. The consideration of the interactions between the filler particles and the organic portion of OSCA materials is critical for first achieving fluxing and interconnection during reflow and second curing the material to develop target thermo mechanical properties for reliability such as Tg, TC, CTE modulus and adhesion after reflow. This paper presents research focused on understanding the impact of filler loading, size, type and surface chemistry on curing, fluxing and interconnection kinetics during reflow processing measured by thermal and rheological methods. Preliminary results indicate the presence of chemical interactions between the filler and organic formulations, as well as complex physical interactions which need to be considered in the design of OSCA-R materials for a device assembly using conventional mass reflow processing.
Design and Fabrication of a Complex LTCC-Based Reactor for the Production of Hydrogen for Portable PEM Fuel Cells
Authors: Belavic Darko , Hrovat Marko , Dolanc Gregor , Hocevar Stanko , Stegel Iztok , Zarnik Marina Santo , Holc Janez , Makarovic Kostja , Batista Jurka , Fajdiga Primoz , Kosec Marija
Published: October 2015

The development process for complex 3D ceramic structures in the integrated evaporator, mixer, reformer and combustor (EMRC) system for the production of hydrogen needed in portable polymer-electrolyte membrane (PEM) fuel cells is presented. Low-temperature co-fired ceramic (LTCC) technology was used to fabricate the ceramic structures of the system. The process started with the design and fabrication of each separate (stand-alone) component, which was developed and tested, and then optimized to fulfill the requirements for the integrated EMRC system. The final 3D ceramic structure consists of 45 LTCC tapes (Du Pont 951PX). The dimensions of the structure are 75 × 41 × 9 mm3 and the weight is about 73 g.
Non-Lead Based Piezoelectric Thin Films: Materials and Energy Harvesting Device
Authors: Kim Seung-Hyun , Leung Alice , Lee Eun Young , Kuhn Lindsay , Jiang Wenyan , Kim Dong-Joo , Kingon Angus I.
Published: October 2015

Non-lead based piezoelectric thin films of (K,Na)(Nb,Ta)O3–BiFeO3 (NKNT-BF) were successfully fabricated by the chemical solution deposition method. Small concentration of BF (5 mol %) added into NKNT films led to a fully dense microstructure and enhanced dielectric and piezoelectric properties compared to pure NKNT films. The measured dielectric constant and piezoelectric d33 values were around 575 and 50 pC/N, respectively. A thin film NKNT-BF piezoelectric cantilever with a micromachined Si proof mass was fabricated for a low frequency vibration energy harvesting device. The average power and the power density of NKNT-BF energy harvesting cantilever with the device volume of 0.007 cm3 were 1.82 μW and 260 μW/cm3 at the resonance frequency of 130 Hz and the acceleration of 0.75 G. Even if these values were somewhat inferior to those of the conventional PZT energy harvesting device, NKNT-BF thin film provided the promising results as an alternative material of PZT for the piezoelectric MEMS applications in the future.
Waveguide Inductive Strip Filter Embedded in LTCC
Authors: Abousaif Ehab , Elshabini Aicha , Barlow Fred
Published: October 2015

Microwave filters are generally designed with microwave transmission lines. However these filters are typically lossy. The waveguide filters using conventional inductive elements such as metal rods and transverse diaphragm have some disadvantages such as complicated structure, high cost and they can be hard to mass produce. But they also have many advantages such as the capability of high power transmission, a non-radiating structure, and their thermal efficiency. A novel waveguide inductive strip filter embedded in LTCC is introduced in this paper where the disadvantages of the conventional waveguide filters are eliminated. By using LTCC technology, the cost will typically be lower, it can easily be mass produce, and these designs can also be tested easily.

The equivalent T-network parameters of the inductive strip mounted in a waveguide and embedded in LTCC substrate were derived. A new iterative technique was used based on the Variation principle. The design formulas and curves of the filter were presented. The design method of the filter was derived by applying the equivalent network of the inductive strip to the usual method of the filter design. A complete set of new curves relating the various filter parameters were introduced. Similar curves can be derived to design similar filters for any frequency band using any dielectric material.

Three-dimensional electromagnetic field modeling and simulation was carried out using HFSS (High Frequency Structure Simulator). An optimization process was done for the designed filter. The modeling and the optimization S-parameters curves are shown.

This paper introduces a new methodology of designing waveguide inductive strip filters embedded in LTCC. The design methodology was derived and presented with formulas and curves. The design steps are explained and verified by examples and results.
3D Net-Shape Manufacturing of Complex Ceramic Parts by High Resolution Stereo Lithography – Examples of Application to Biomedical and Industrial Products
Authors: Lafon Jean Baptitse , Chaput Christophe , Gaignon Richard , Delage Cyrille
Published: October 2015

Solid Freeform Fabrication (SFF) processes are fairly new shaping methods, which allow the direct fabrication of complex ceramic structures, without tooling or machining, on the basis of a component CAD file. SFF techniques provide an attractive answer for applications with the need to produce custom designs while also controlling the product structure or producing multimaterial devices demanding improved properties or multifunctional components.

Stereolithography (SL) is a layer manufacturing process based on the space-resolved polymerisation of a UV photocurable compound consisting in a dispersion of ceramic particles in a monomer containing a photoinitiator. Improvements in the SL process, notably understanding and driving the key parameters influencing the 3D resolution of the reactive compound, now make it possible to directly manufacture useful 3D ceramic parts with final properties similar or identical to those obtained from traditional processes.

SL processing applications are numerous and include medical implants, complex microwave devices, refractory molds and cores, MEMS, microfluidic networks for micro reactors, drug delivery devices or biological analysis, etc...
Integration of Ni-Cu-Zn Ferrite in LTCC-Modules
Authors: Rabe Torsten , Naghib-zadeh Hamid , Glitzky Carsten , Töpfer Jörg
Published: October 2015

Integration of magnetic functional components in LTCC circuit boards calls for co-firing of dielectric and ferrite tapes. Ni-Cu-Zn ferrites with permeability of μ =900 were developed which can be fully densified at the standard LTCC sintering temperature of 900 °C. Successful co-firing of this ferrite with dielectric tapes requires the adaptation of the shrinkage behavior of the materials as well as the thermal expansion during the cooling period - especially in the temperature range below the transformation point of the glassy phase of the dielectric tape. To match these preconditions, a new dielectric LTCC material with steep sintering curve and high thermal expansion coefficient was designed. Sintered multilayer composed of Ni-Cu-Zn ferrite and tailored dielectric tapes are free of cracks and possess no open porosity. No significant interdiffusion between the ferrite and dielectric tapes was found by EDX measurements. Compared to pure ferrite laminates the permeability of co-sintered Ni-Cu-Zn ferrite layers is drastically reduced to 400, i.e. a decrease of more than 50 %.

To investigate the origin of this permeability reduction, Ni-Cu-Zn ferrite laminates were sintered separately, and in combination with alumina release tapes or dielectric tapes, respectively. SEM and EDX analysis of co-fired laminates reveal differences in the ferrite grain growth behavior. Ferrite laminates with homogeneous microstructure and grain size up to 50 μm exhibit large permeability. However, growth of ferrite grains does not take place near the interface between ferrite and release or dielectric tapes. There is a strong correlation between high permeability and volume fraction of large ferrite grains. Regions of fine and coarse grains inside the ferrite layers show different bismuth concentration; the Bi-content is larger in regions of fine ferrite grains.
Laser Printing of RFID Antenna Coils on Ceramic
Authors: Büttner Dustin , Krüger Klaus , Zobrist Beat , Schönberger Andreas , Jung Dieter
Published: October 2015

Printed electronics are a major field of activity in research and industrial applications nowadays, especially in thick-film technology. Within the last decade, large progress was made to digitally print electronic circuits, in order to supplement or replace the established screen printing technology. The advantage of digital printing is its capability to rapidly produce any layout desired at minimum space requirements. This highly flexible production method is especially applicable for prototyping and small series productions.

Electrophotography, commonly known as laser printing, has been considered very rarely as a method for digital printing of electronic circuits. It is a completely solvent-free method with high speeds and a high potential regarding precision. At Helmut Schmidt University, electrophotography is tried to be established as an alternative method to print silver lines as basis for a conductive layout.

After a first set of conductive silver lines was printed and the results were published, this paper describes the development from initial conductivity to a functional circuit element. Deficits in toner transfer to tape are examined and a more effective transfer method is established. Furthermore, the performance of the used silver toner is improved, and the best toner for the desired application is determined. Silver lines are printed on green tape and sintered in a co-firing process, as well as on ceramic using a post-firing process. After reaching a certain level of quality, a functional RFID antenna coil is printed that proves the capability of the process to create a conductive layout.
3D-CERAMIC INTERCONNECTION DEVICES
Authors: METAYER Pascal
Published: October 2015

Electronic packaging can benefit from 3D interconnect devices that combine mechanical and electrical functions on a single 3D-shape part. Design freedom, miniaturisation, simple assembly process, low cost and reliability are some of the advantages that stimulate innovation or replacement of existing products. This monolithic concept was developed for high volume production with moulded thermoplastics as materials used for circuit carriers. Ceramic counterparts have been implemented so far to a smaller extent although their thermal, mechanical and dielectric make them suitable for applications requiring high dimensional stability. This article presents the use of ceramics for 3D-interconnect devices. Ceramics properties will be highlighted with some existing applications. Fabrication processes will be overviewed with emphasis on laser structuring.
3D Branched Nanowire Photoelectrodes for High Efficiency Solar Water Splitting and Hydrogen Production
Authors: Sun Ke , Kargar Alireza , Zhou Yuchun , Madsen Kristian , Jing Yi , Wang Deli
Published: October 2015

We report a high efficiency water splitting photoelectrochemical cell based on 3D branched nanowire (NW) heterostructures photoelectrodes. The 3D NW heterostructure is composed of an n-Si NW core and ZnO NW branches and fabricated from cost-effective low temperature solution-based synthesis methods. Specifically, we report the studies of 3D n-n NW heterojunction photoelectrode efficiency (photocurrent) dependence on the core and branch NW length, where longer Si NW cores give a larger anodic photocurrent response as well as a recombination current, and longer ZnO NW branches increase the cathodic photocurrent response and the dark current.
Crack Propagation and Detection in PZT-Multilayer Ceramics
Authors: Kühnlein Tobias , Poller Silvan , Rauscher Martin , Klonczynski Alexander
Published: October 2015

Piezo multilayer ceramics are increasingly used under extreme condition such as high pressures in engine injection systems. The mechanical stability and reliability of the ceramic multilayer is of major importance for proper operation. Critical functional defects are caused by material fracture and flaw extension in the device. The flaw propagation in PZT-multilayer ceramics under mechanical load was examined using impedance spectroscopy and three-point-bending studies. Initial flaws were generated by applying a sinus ac-field on the specimens. The cracks were successively promoted and after the release of the external mechanical load the impedance spectroscopy was conducted. As a measure for flaw extension, the shift in the resonance frequencies and the sub-resonance height of the impedance spectroscopy was used. A functional dependence of the resonance frequency and the phase shift on the crack length was found.

The crack propagation was studied on flaws starting at the positive and negative electrode, respectively. The maximum fracture strength as well as the crack path depends on the electrode potentials. The variation in the fracture strength was caused by the different observed fracture mode: interface cracking, matrix-cracking and a combination of both. The morphology of the fracture faces was ascribed to an anisotropic behaviour, which is created by the sample processing, e.g. the poling process. A modified poling procedure with a lower poling temperature was analysed, which yielded a reduction of the anisotropy of the electrode strength. Impedance spectroscopy was found as a reliable measurement tool for automated flaw detection in PZT-multilayer ceramics.
Surface Micro Machined Actuators on Piezoelectric Bulk Material
Authors: Zaehringer Sandy , Widamnn Elisabeth , Schwesinger Norbert
Published: October 2015

Using circular discs of piezoelectric material an easy adaptation to well-known silicon surface micro machining technologies is possible. Thus, several interdigitated electrodes layouts have been positioned on a planar lead-zirconate-titanate disc via lift off processes. Because of an inhomogeneous electric field distribution the actuated areas on the disc conduct a symmetric deformation of the bulk material without any need of a further passive membrane, as is necessary regarding common piezoelectric membrane actuators.

The most interesting deformation was shown by star shaped interdigitated electrodes. It was an overall downward movement (i.e. the side opposite the electrodes) of the actuated area and a center movement in the opposite direction about 25% of the downward movement. This phenomenon is further investigated, especially with regard to increasing the upward movement. Therefore, the behavior of the actuated area has been more thoroughly tested, using laser vibrometry, speckle imaging and white light interferometry. Based on the thus salvaged data, those actuators have been investigated especially concerning their deformation behavior in various clamping modes either during polarization and/or during actuation.
BENZENE GAS SENSOR BASED ON SCREEN-PRINTED PZT CANTILEVERS
Authors: Debéda Hélène , Vázquez Rosa M. , Lakhmi Riadh , Arregui Francisco J. , Lucat Claude , Llobet Eduard , Zamarreño Carlos R. , Calavia Raul , Delgado Marc
Published: October 2015

Benzene gas detections at ppm level are performed at room temperature with a piezoelectric resonant type sensor. For this purpose, self-actuated PZT cantilevers made of multi-layered Au/PZT/Au beam (8×2×0.1 mm3) partially released from an alumina substrate, are fabricated thanks to the association of screen-printing and sacrificial layer technique. Then, PZT cantilevers are functionalized with different organic (polypyrrole and polyaniline) and inorganic (active carbon and tin dioxide) coatings. The high sensitivity (tens of hertz/ppm) is achieved by using the unusual 31's longitudinal vibration mode of the PZT cantilever, unlike classical modes like transversal bending resonating mode. With the second “in-plane” 31-longitudinal mode of the PZT beam, benzene detection at sub-ppm level is expected with the organic and inorganic sensitive coatings. These very interesting results already demonstrate the potentialities of coated PZT cantilevers for gas detection and can be extended to species detection in liquid media.
New Ferro L8 LTCC System Ready for High Reliability Electronic Packaging Applications
Authors: Henry Jim , Brown Orville , Graddy Ed , Stadnicar Ed , Gardner Bob
Published: October 2015

Ferro glass and conductor core competencies have combined to develop a unique and superior electronic packaging system. Recent advances have resulted in a new mechanically robust packaging system for high frequency packaging applications. The new system is called L8 and is the result of Ferro glass technology combined with Ferro expertise in conductive pastes.

Packaging of complex, high reliability electronic devices require ceramic multilayer systems that can be co- fired with low loss conductors to form a hermetic environment. This is necessary as the device will be required to perform reliably in harsh environments for extended periods of time. Devices used in satellite, avionics and shipboard applications are just a few examples of applications where packaging of this type is a requirement.

L8 is based on a ceramic filled glass system with excellent low loss characteristics that have been measured up to 30 GHz. L8 has the further advantages of excellent tensile and flexural strength. The newly developed conductors and tape system provide a range of design options including the potential to significantly lower cost without sacrificing reliability for high volume manufacturing.

Our paper will introduce the L8 dielectric along with 4 conductor systems that comprise the L8 LTCC System. Studies on embedded and surface resistor pastes performance are also presented.
Thick Film Approaches in High Power LED Array Module
Authors: Kim Hyo Tae , Kim Jihoon , Yoon Young Joon , Kim Chang Yeoul , Kim Jong-hee , Kim Heung-soon , Song Gi-seok
Published: October 2015

Light emitting diode, LED, has become a popular device for display and lighting applications. Among them, high power LED array modules are especially interested in the field of street light system, recently. High power LED array module is generally consisted of several pieces of LEDs which are mounted on the PCB with the combination of series and parallel circuits according to the designed operating voltage and power consumption, i.e. total wattages. Since the life time expectancy and brightness of LED are greatly influenced by the operation temperature of LED, thermal management technology of LED module including system design, heat transfer and dissipation become a hot issue in these days. In this work, we would like to present several thick film approaches to fabricate thermally efficient high power, i.e. LED array modules with over 50 watts by using different array package design, materials selection and film forming techniques. Here, we will demonstrate 50 watts LED array modules directly coupled with aluminum, copper or silicon heat sinks which operates at 12volts using 4 × 9, 4 pieces of LED in series multiplied by 9 arrays in parallel, LED array circuit. The microstructure of metal-ceramic multilayers and interfaces, and the heat transfer performance of the LED array modules will be presented.
Measurement of nitrogen monoxide levels in gas flows with a micro total analytical system based on LTCC
Authors: Geiling Thomas , Welker Tilo , Bartsch Heike , Müller Jens
Published: October 2015

The measurement of nitrogen monoxide (NO) concentration levels is a vital aspect of environmental analysis and the so called CHNS analysis. The chemiluminescent reaction with ozone in the gas phase is a well-established method for the measurement of atmospheric concentration levels in the range from 4 ppb up to 100 ppm.

In this contribution we present the design of a so called micro total analytical system (μTAS) for NO measurements designed in ceramic. Low temperature co-fired ceramics (LTCC) have proven to be the ideal technology, since they offer high chemical and thermal stability as well as high degree of freedom of design. The article gives an overview of the design process with emphasis on manufacture of the components and technological challenges regarding life-time.
Novel Technology Options for Multilayer-Based Ceramic Microsystems
Authors: Partsch Uwe , Goldberg Adrian , Ihle Martin , Hagen Gunter , Arndt D.
Published: October 2015

Ceramic multilayer technologies as LTCC (Low Temperature Cofired Ceramics) or HTCC (High Temperature Cofired Ceramics) are applied for the fabrication of highly integrated ceramic microelectronic packages. Furthermore ceramic multilayer technologies offer the possibility of the additional integration of 3-D-structures for multilayer-based microsystems.

The paper presents a new machine for tape/ multilayer structuring combining micro punching tools and micro UV-laser ablation/ cutting. The application for the production of different multilayer based components is described (e.g. LTCC-based PEM fuel cell system, LTCC-based pressure sensors). Aerosol printing is a new technology e.g. for rapid prototyping for LTCC multilayer and 3-D-deposition of functional layers on LTCC. Advantages and limitations of the technology are discussed.
Fabrication of an Inductively Coupled Plasma Antenna in LTCC
Authors: Taff J. , Yates M. , Lee C. , Shawver S. , Browning J. , Plumlee D.
Published: October 2015

With the size reduction of satellites, the need for miniaturized propulsion systems is increasing. This has led to research funding for the miniaturization of chemical and electric propulsion by NASA and the Air Force Office of Scientific Research (AFOSR). Miniaturized electric propulsion research has been an active area of interest recently. Electric propulsion systems are interesting candidates for miniaturization due to efficiency and the reduction in onboard propellant and the ability to apply existing techniques in electronic fabrication.

A miniature electrostatic thruster is being developed in LTCC at Boise State University. The thruster is composed of an antenna to create the plasma, a cylinder to contain the plasma and grids to extract the plasma beam at high velocity. In this work, the development of the inductively coupled plasma (ICP) antenna in LTCC will be presented. This antenna is fabricated using DuPont's 951 Low Temperature Co-fired Ceramic (LTCC). A Direct Write is used to apply silver paste for the spiral ICP antenna. Using LTCC allows for the antenna to be embedded in the device under a thin sheet of LTCC dielectric, which protects the antenna from ion back bombardment during operation. This thin sheet is the seventh layer of the total device, with the ICP antenna one layer below the top. The design of the antenna is based on the research done by J. Hopwood. This paper discusses the fabrication and performance of the ICP antennas in LTCC. These ICP antennas are operated at pressures from 10 mTorr to 1 Torr with radio frequencies (RF) of 500 MHz to 1 GHz to inductively couple with low pressure argon to produce plasma. The performance of the antennas will be verified with data showing the start and stop power of the plasma at various pressures and an electric field map of the RF field above the antenna.
Carrier Transport through Grain Boundaries in Highly Transparent Conductive Ga-Doped ZnO Polycrystalline Films
Authors: Yamamoto Tetsuya , Yamamoto Tetsuya , Sato Yasushi , Makino Hisao , Yamamoto Naoki
Published: October 2015

We investigated the effects of grain boundaries on the carrier mobility of polycrystalline highly transparent conductive Ga-doped ZnO (GZO) films with thicknesses in the range from 100 to 500nm on glass substrates at a temperature of 200°C. GZO films were prepared by ion-plating deposition with DC arc discharge. A systematic study has been made of the thickness dependence of the structural, electrical and optical properties of GZO films. The full width at half maximum (FWHMω) of the (0002) rocking curve was found to decrease with increasing thickness, whereas the grain size increased with increasing thickness. The comparison of the Hall mobility with the optical mobility calculated by analysis using the simple Drude model combined with the Tauc-Lorentz model of data obtained by spectroscopic ellipsometry (SE) demonstrates that grain boundaries present a significant obstacle to free carriers in GZO films with thicknesses of up to 344nm. In 344-nm-thick GZO films with a high carrier concentration of 1.23×1021 cm−3, the Hall mobility of 29cm2/Vs is close to the optical mobility, i.e. the carrier mobility in the grain bulk. In such films, a very low resistivity of 1.87×10−4 Ωcm was obtained. This indicates the very small contribution of grain boundaries to the total resistivity of the GZO films.
Zinc Oxide Modeling to Create Semiconductor Dendrites by Using Micro Stereolithography
Authors: Tasaki Satoko , Kirihara Soshu
Published: October 2015

Zinc oxide ceramics exhibit various semiconductor properties through optimized elements or materials doping. The elements doping of aluminum or gallium can control the electric conductivity, and composites doping of indium and rare earth such as yttrium can increase the thermoelectric conversion efficiency. In this investigation, dendritic lattice structures of the zinc oxide semiconductors with periodically ordered arrangements or self similar patterns were fabricated successfully to increase the surfaces area and porosity values by using micro patterning stereolithography of a computer aided design and manufacturing. These semiconductor dendrites with penetrable paths and extensive interfaces will be used for fluid and heat flow receptors and applied to the novel sensor devices and energy generators. The dendritic lattice models sliced into a series of cross sectional patterns with uniform thickness by using a stereolithographic file format convertor. These numerical data were transferred into the micro processing equipment. High viscosity slurry material was prepared through the mixing of photo sensitive acrylic resin and the zinc oxide particle at 30 % in volume fraction. The slurry was supplied on a flat substrate with 8 μm in layer thickness by using a mechanical knife edge. The cross sectional image was exposed on the slurry surface by using digital micro mirror devices. Through the layer by layer processes, the solid component was obtained with micrometer order part accuracies. The dense ceramic sample was purchase after de-waxing and sintering process.
Evaluation of Ceramic Substrates for High Power and High Temperature Applications
Authors: Kulkarni Srikanth , Arifeen Shams , Patterson Brian , Potirniche Gabriel , Elshabini Aicha , Barlow Fred
Published: October 2015

Ceramic substrates with thin film and thick film conductor traces are widely used in microelectronic packages for high temperature operation. In high power applications where the maximum current in the package may be hundreds of amperes, much thicker conductive traces are normally required. For such applications, Direct Bonded Copper (DBC), Direct Bonded Aluminum (DBA) or Active Metal Bonded (AMB) substrates are good candidates. These substrates provide low electrical resistance and high ampacity, thereby enable the design of high power circuits for high temperature operation.

The most commonly observed failure mode in these substrates is the delamination of metal layer from the ceramic. The lifetime of a ceramic substrate can be significantly reduced by the processing conditions such as maximum process temperature, and the process gases that the substrates are exposed to. It has also been shown that the propagation of cracks in the ceramic can be abated by dimpling the metal layers along edges and corners.

In order to evaluate the effectiveness of these types of substrates for power applications, substrates with various combinations of metal thicknesses and ceramic composition (Al2O3 and AlN) were evaluated for delamination as a function of thermal shock cycles. These samples included both dimpled and non-dimpled metallization. The samples were thermally cycled between −40 °C and 200 °C. A few of these substrates were exposed to forming gas at 340 °C prior to thermal cycling to imitate process conditions. Sample randomization was performed to provide statistically significant data. After a certain number of thermal cycles, delamination cracks were observed to nucleate and propagate in the substrates. Data regarding the reliability of these substrates as a function of thermal shock cycles is presented in this paper, along with failure mechanisms that are commonly observed. Computer simulations were performed to understand the conditions that lead to delamination cracks, and to estimate the crack growth rates in these substrates.
Advanced 3D roughness analysis for the characterization of ceramic surfaces
Authors: Strass Karl-Heinz
Published: October 2015

Advanced processes often hinge on the ability to reproduce specific surface characteristics. While throughout the past century, the mean roughness value, also expressed as Ra has often been used as the main parameter to classify a surface's ability to retain oil and provide a functional bearing surface, the materials, processes and required functionalities of modern surfaces go far beyond that application.

Superficial interfaces now often determine the ability of a consecutive layer to adhere to the substrate or, amongst others, enhance a surface's ability to exchange electrons or other elements. In many applications the surface itself enables the process the device is intended to deliver.

The paper discusses various approaches to measure surface roughness, and takes a closer look at more advanced surface roughness parameters that allow the user to more accurately and precisely determine a surface's ability to function within its desired boundary conditions.

We will review various technologies widely used to measure surface topographies, from the traditional stylus profilometry, to white light interferometry, confocal microscopy to optical systems that combine several of the advantages into one technology.

Almost none of the surfaces functions today are based on surface properties of a single line, hence the paper will review the correlation between single line scan metrology and real 3D metrology. Acquiring 3-dimensional data provides the user with significantly more information. Any directionality of surface properties can now be evaluated by taking advantage of more advanced and complex roughness parameters that indicate for instance, anisotropies of surface preparation processes.
X-Ray Inspection of LTCC Devices
Authors: Zaraska Krzysztof , Gaudyn Janina , Bieńkowski Adam , Dohnalik Marek , Czerwiński Andrzej , Płuska Mariusz , Machnik Monika
Published: October 2015

The appeal of LTCC (Low Temperature Cofired Ceramic) process lies in the possibility of creating multilayer (3D) structures, integrating conductor paths, passive elements, such as inductors and resistors and resonance cavities. Unfortunately, the very nature of cofired device makes post-firing optical inspection of buried elements impossible, as the ceramic material is opaque to visible light. This limitation, however, does not exist at X-ray wavelengths. The aim of this paper is to provide a practical overview of application of high resolution X-ray imaging for non-destructive inspection and fault detection in multilayer LTCC structures. First, we present a simplified mathematical description of X-ray absorption inside an LTCC structure and demonstrate that due to physical properties of substrate (glass/Al2O3 ceramic), conductor material (silver) and cavity fill (air), a high contrast image of the investigated structure can be obtained. Next, we show application of a commercial off-the shelf industrial X-ray system for imaging various faults in LTCC structures, such as: via voids (caused by inadequate filling of a via hole with conductor material), microcracks, paste creep (during lamination, excess via conductor leaks out of the via hole and in between the tape layers, shorting the via to an adjacent circuit), interruptions in conductor paths and alignment errors. We also demonstrate application of computed tomography for verifying 3D geometry of buried resonance cavities and detecting tape delaminations. Finally, we discuss limitations of the method, related to structure thickness (number of layers), material composition, imaging geometry and equipment characteristics, such as detector resolution and spatial noise.
The Design and Testing of Fluidic Oscillators made in LTCC
Authors: Müllner David P. , Plumlee Donald G.
Published: October 2015

The interest in using fluidic devices as replacements for electronic logic circuit devices has seen renewed interest as NASA looks for ways to operate in harsh interplanetary environments. The size, multi-layer capabilities and ability to incorporate fluidic channels in a ceramic substrate make Low Temperature Co-Fired Ceramics (LTCC) a viable platform for development of these fluidic devices. Fluidic oscillators and fluidic diodes are being developed at BSU in LTCC. Fluidic oscillators can be used for measuring flow rates, fluid viscosity as well as a replacement for electronic oscillators. Fluidic diodes can be used as check-valves or as replacements for electronic diodes. In this work, we will describe the development and testing of a fluidic oscillator in LTCC.
Chemical Solution Deposition of High-Quality SrRu O3 Thin-Film Electrodes and the Dielectric Properties of Integrated Lead Lanthanum Zirconate Titanate Films for Embedded Passives
Authors: Narayanan Manoj , Ma Beihai , Koritala Rachel , Tong Sheng , Balachandran U.
Published: October 2015

Ferroelectric film-on-foil capacitors are suitable to replace discrete passive components in the quest to develop electronic devices that show superior performance and are smaller in size. The film-on-foil approach is the most viable method to fabricate such components. Films of Pb0.92La0.08Zr0.52Ti0.48O3 (PLZT) were deposited on SrRuO3 (SRO) buffer films over nickel and silicon substrates. High-quality polycrystalline SRO thinfilm electrodes were first deposited by chemical solution deposition. The optimized crystallization temperature of the SRO films was determined by studying the phase, microstructure, and electrical properties. A phase pure, dense, uniform microstructure with grain size < 100 nm was obtained in films crystallized between 700 and 750°C. The room-temperature resistivity of the SRO films crystallized at 700°C was ~800–900 μΩ-cm. The dielectric properties of sol-gel derived PLZT capacitors on SRO-buffered nickel were evaluated as a function of temperature, bias field, and frequency, and the results were compared to those of the same films on silicon substrates. The comparison demonstrated the integrity of the buffer layer and its compatibility with nickel substrates. Device-quality dielectric properties were measured on PLZT films deposited on SRObuffered nickel foils and found to be comparable to those for PLZT on SRO-buffered silicon and expensive platinized silicon. These results suggest that SRO films can act as an effective barrier layer on nickel substrates suitable for embedded capacitor applications.
Silver processing in thick film technology for power electronics
Authors: Eberstein Markus , Wenzel Marco , Feller Claudia , Seuthe Thomas , Gora Frieder
Published: October 2015

Processing of Ag-equipped thick film modules is still challenging due to well-known issues of warpage of Ag-containing LTCC substrates or undesired coloring of Ag-surrounding ceramics. To increase the workability of Ag based thick film modules, enhanced control over these effects is necessary. From the experimental background as well as the chemical and thermodynamic nature of the element Ag, conclusions regarding essential properties during Ag-high temperature processing, like initial oxidation, transport via the vapor and glassy phase, and reduction are discussed. Taking into consideration a possible occurrences of this phenomenas as activated/deactivaed dependent on sintering conditions, explanation of unwanted maufacturing results like LTCC staining, warpage, glass thinning and setter memory effects are possible. From a technical standpoint, there are roughly two temperature ranges of relevance for processing silver metalized thick film structures. Between approximately 300 °C and 700 °C fast transport mechanisms of silver through the gaseous phase take place. Control can be achieved via governing the silver manufacturing, oxygen partial pressure, organic composition, powder conditioning and temperature-time schedule. Above approximately 600 °C, slower transport mechanisms of silver through the glassy phase and possible reduction of Ag(I) become evident. These effects originate corresponding impacts on the sintering kinetics. Here, control can be achieved via governing the glass composition, redox potential and, again, temperature-time schedule.