bluuebunny/crossref_metadata_2025_split huggingface dataset:
Wafer Level Solder Bumping and Flip Chip Assembly with Solder Balls Down to 30μm
Authors: Oppert Thomas , Dohle Rainer , Franke Jörg , Härter Stefan 
Published: October 2015

The most important technology driver in the electronics industry is miniaturization mainly driven by size reduction on wafer level and cost. One of the interconnection technologies for fine pitch applications with the potential for highest integration and cost savings is Flip Chip technology. The commonly used method of generating fine pitch solder bumps is by electroplating the solder. This process is difficult to control or even impossible if it comes to ternary or quaternary alloys. The work described in this study addresses the limitations of existing bumping technologies by enabling low-cost, fine pitch bumping and the use of a very large variety of solder alloys. This flexibility in the selection of the solder materials and UBM stacks is a large advantage if it is essential to improve temperature cycling resistance, drop test resistance, or to increase electromigration lifetime. The technology allows rapid changeover between different low melting solder alloys. Tighter bump pitches and a better bump quality (no flux entrapment) are achievable than with screen printing of solder paste. Because no solder material is wasted, the material costs for precious metal alloys like Au80Sn20 are much lower than with other bumping processes. Solder bumps with a diameter between to date 30 μm and 500 μm as well as small and large batches can be manufactured with one cost efficient process.
To explore this potential, cost-efficient solder bumping and automated assembly technologies for the processing of Flip Chips have been developed and qualified. Flip Chips used in this study are 10 mm by 10 mm in size, have a pitch of 100 μm and a solder ball diameter of 30 μm, 40 μm or 50μm, respectively.
Wafer level solder application has been done using wafer level solder sphere transfer process or solder sphere jetting technology, respectively. The latter tool has been used for many years in the wafer level packaging industry for both Flip Chip and chip scale packaging applications. It is commonly known in the industry as a solder ball bumping equipment. For the described work the process was scaled down for processing solder spheres with a diameter of 30 μm what was never done before that way worldwide.
The research has shown that the underfill process is one of the most crucial factors when it comes to Flip Chip miniaturization for high reliability applications. Therefore, high performance underfill material was qualified initially [1].
Final long term reliability testing has been done according to MIL-STD883G, method 1010.8, condition B up to thirteen thousand cycles with excellent performance of the highly miniaturized solder joints. SEM/EDX and other analysis techniques will be presented. Additionally, an analysis of the failure mechanism will be given and recommendations for key applications and further miniaturization will be outlined.
Build-up Electrical Insulation Material with Low-Dielectric Loss Tangent, Low-CTE and Low-Surface Roughness
Authors: HORIKI Eita , SUZUKI Isao , TANAKA Toshiaki , UENISHI Akihiro , KOUYANAGI Hiroshi 
Published: October 2015

With the increasing speed of information and communication equipments in recent years, together with the high-speed signal processing of LSIs, there is a requirement for build-up electrical insulation materials (used in IC package substrates) to have low-dielectric loss tangent which reduces dielectric loss so as to achieve low transmission loss in the high-frequency GHz bands. At the same time, there is an increasing need for materials to have low-CTEs (Coefficient of Thermal Expansion) so as to ensure highly reliable substrates.
With ou formulation technology, we have developed a next-generation film-shaped build-up electrical insulation material compatible with high-frequency signal transmission by using a composition of practical thermosetting epoxy resin, which has realized both a low-dielectric loss tangent and at the same time, a low-CTE.
In addition, this material can show a low-surface roughness after the film desmear process. It is thus expected to help reduce not only dielectric loss by means of a low-dielectric loss tangent, but also conductor loss caused by the skin effect, and will promote fine line formation by means of SAP (Semi Additive Process).
European R&D Trends in wire bonding technologies
Authors: Schneider-Ramelow M. , Göhre J.-M. , Geißler U. , Schmitz S. , Lang K.-D. 
Published: October 2015

Asian industry and development is currently very focused on replacing extremely expensive Au wire with Cu or Pd-plated Cu in IC (mass production) packaging technologies (ball/wedge bonding). In contrast, Europe traditionally is researching and developing in the field of wedge/wedge bonding using heavy wire (&gt; 100 μm) for power electronic modules or standard (thin) wire (&lt; 100 μm, mostly 25–50 μm) for chip-on-board (COB) applications.
One primary failure mechanism limiting the lifetime of power modules is Al wedge lift-off due to the different coefficients of thermal expansion (CTE) of the Al wedge and the chip (Si). This classical type of fatigue cracking can be reduced by using materials of higher strength and/or lower CTE. Key strategies include doping or alloying elements and/or optimizing bonding conditions to improve the microstructure. Cu-based wire or Cu-Al bimetal ribbons are another option, although these include changes to the chip structure and metallization.
AlSi1 has been the industry standard bonding material in wedge/wedge thin wire bonding for many years. Its thermal stability is limited at temperature above ≈100°C due to recrystallization, grain growth and Si coagulation. For example, glob top material curing processes used in chip on board (COB) applications (e.g. several hours at 160°C) can decrease the strength of standard AlSi1 wire to less than 60% of its original value. Research and development is currently attempting to improve this situation by alloying and doping Al base material to increase high-temperature behavior or by using Al-coated Au or Cu wires.
The presentation will give an overview of alternative wedge/wedge wire bonding materials and discuss the challenges to processing and reliability.
Improved compensation for a reduction stepper to meet the challenges for advanced packaging applications
Authors: Webb James E , Gardner Steven , DaSilveira Elvino 
Published: October 2015

Advanced packaging manufacturers require steppers that will provide solutions for the challenges encountered with new advances in wafer-level packaging technologies such as TSV, eWLB, silicon and glass interposers being utilized in leading edge mobile devices. Step and repeat photolithography systems capable of finer imaging with tighter overlay are being introduced to meet the challenging manufacturing requirements associated with the mix and match needed for volume production on larger wafers.
A 2X reduction stepper with unique features incorporated that extend the range of compensation is necessary to achieve the tighter specifications needed for many advanced packaging applications printed on 300 to 450mm wafers. A high throughput projection optical system is used to expose circuit patterns from a reticle mask onto a substrate to image features with the optimal fidelity required for advanced packaging technologies. The camera incorporates 350–450nm light from a mercury arc lamp that is transmitted through the mask containing circuit patterns. The imaging field prints a large 52mm × 66mm area in a single exposure. These features enable a system to process wafers in fewer shots which result in higher throughput using lower power.
Substrates are positioned with a precise X, Y, Θ stage by locating marks using an off-axis, bright field alignment system with fully trainable mark feature capability. The approach results in precisely placed features within a layer and from layer to layer without directly referencing the reticle. The integrated metrology and precision positioning subsystem technologies are combined with a low distortion projection lens and a wide range of adjustments, allowing the stepper to be integrated into a production line in a mix and match setup with other lithography systems. This equipment can be used to image critical layers on substrates while ensuring grid registration and alignment with other lithography systems that are also printing images in the same process line.
Several important global and intra-field image placement relationships for devices requiring multiple layer patterning have been combined in the stepper matching correction software. Further adjustment to the tool can be made to improve overlay when incorporated with fab-wide yield management software for automated, real-time process control. The types of adjustments needed and techniques that can be applied to compensate for image placement errors over large areas are discussed.
Transferable Redistribution Layers (TRDL)
Authors: Dunphy Suzanne , Herndon David 
Published: October 2015

Since the early 1990's, redistribution layers (RDL) have been used to relocate and change the pattern of the bond pads on die. RDL allows legacy parts that were designed as wirebond die to be flip-chip soldered to Printed Wiring Boards (PWBs). The flip-chip soldering technology shrinks overall board size as well as shortening electrical connection lengths. Since the introduction of this technology a couple decades ago, RDL has been performed at the wafer level through a back end of line (BEOL) process performed directly on the active surface of the wafer.
Transferable redistribution layers (TRDL) may become the next evolutionary step for RDL and provide a viable solution to complex RDL. The TRDL technology allows for multi-layer RDL to be transferred from a non-active surface to an active one. TRDL is particularly important for prototyping and quick-react situations. The TRDL wafers can be processed in parallel with obtaining the active components, thereby drastically reducing the time from design to completed components.
Z-Interconnect Technology - A Reliable, Cost Efficient Solution for High Density, High Performance Electronic Packaging
Authors: Lauffer John M. , Knadle Kevin 
Published: October 2015

Common themes across all segments of electronic packaging today are density and performance. High density interconnect (HDI) technology is one of the most commonly utilized methods for electronic package density improvement, while many different areas have been investigated for performance improvement, from low loss dielectric and conductor materials, to via design and via stub reduction. Electrical performance and density requirements are sometimes complementary, but often times, conflicting with one another.
This paper will describe the design, materials, fabrication, and reliability of a new Z-Interconnect technology that addresses both high density and high performance demands simultaneously. Z-Interconnect technology uses an electrically conductive adhesive to electrically interconnect several cores (Full Z) or sub-composites (Sub Z) in a single lamination process. Z-Interconnect technology will be compared and contrasted to other commonly used solutions to the performance and density challenges. HDI or sequential build-up technology is a pervasive solution to the density demands in semiconductor packaging and consumer electronics (e.g. Smart phones), but has not caught hold in HPC or A&D printed wiring board (PWB) applications. One solution for PWB electrical performance enhancement is plated through hole (PTH) stub reduction by “back drilling” the unwanted portion of the PTH.
Pb-free reflow and Current Induced Thermal Cycling (CITC) test results of product coupons and specially designed test vehicles, having component pitches down to 0.4mm, will be presented. Z-Interconnect test vehicles have survived 6X Pb-free (260C) reflow cycles, followed by greater than 3000 cycles of 23C–150C CITC cycles. Test vehicle and product coupons also easily survive 10 or more 23C–260C CITC cycles.
Using Visual Analytics to Determine the Utilization of Preoperative Anesthesia Assessments
Authors: Gruss C.L. , Ehrenfeld J.M. , Wanderer J.P. 
Published: October 2015

SummaryBackground: Preoperative assessments are a required and essential element of anesthetic care, yet little is known about the utilization of these documents by clinicians who are not part of the anesthesia care team. As part of perioperative workflow restructuring, we implemented a data visualization technique of electronic medical record audit log data to understand the utilization of preoperative anesthesia assessments by non-anesthesia personnel.Methods: An audit log cache containing 140 days of data was queried for all accesses of preoperative anesthesia assessment documents for any patient who had a preoperative anesthesia assessment that was accessed during that period. User roles were aggregated into categories. Descriptive statistics and data visualization were generated using R (R Software Foundation, Vienna, Austria). Comparisons were performed with the Wilcoxon signed rank test with continuity correction.Results: During the study period, 73 802 (0.015%) of the 485 062 902 audit log accesses were pre-operative anesthesia assessments representing 412 departments, 302 user roles, and 3 916 distinct users who accessed preoperative anesthesia assessments from 14 235 surgical cases. Each assessment was accessed 2.9 times on average. Assessments performed in the preoperative anesthesia assessment clinic were accessed more frequently than those created on the day of surgery in the preoperative holding room (3.58 ± 5.18 v. 1.98 ± 1.76 average views; p<0.0001). We observed accesses of these documents by pathology and general surgery researchers, as well as orthopedics attending physicians accessing documents that were two years old.Conclusions: This approach revealed patterns of utilization that had not been previously identified, including usage by surgical residents, surgical faculty, and pathology researchers both before and after the surgical event for which the documents are generated. Knowledge of these dependencies directly informed perioperative workflow restructuring efforts. This visual analytic approach could be broadly utilized to understand documentation dependencies in a variety of clinical contexts.
The Aesthetic Justification of Existence: Nietzsche on the Beauty of Exemplary Lives
Authors: Church Jeffrey 
Published: October 2015

ABSTRACT
A disagreement about the nature of Nietzsche's “aesthetic justification of existence” has recently emerged in the literature. In this essay, I argue that the disagreement stems from a common but mistaken assumption that Nietzsche focuses on works of art to justify life. Instead, in the Untimely Meditations, Nietzsche shifts to the beauty of exemplary individuals to justify life. Through an examination of the Kantian practical arguments in the Untimely Meditations, I show how the scholarly debate can be overcome and suggest that Nietzsche's early period views can illuminate the basis of some of his late period ideals, such as the overman and philosopher of the future.
Marx, Nietzsche, and the Workshops of History
Authors: Norman Judith 
Published: October 2015

ABSTRACT
Marx and Nietzsche are often compared as practitioners of a hermeneutic of suspicion. I pursue this comparison by focusing on an overlooked similarity between the two. In strangely similar passages, Marx (in Capital) and Nietzsche (in the Genealogy of Morals) introduce explicitly theatrical scenarios into the course of their discussions, complete with what Marx calls dramatis personae, where we witness a descent into a workshop (in some sense underground) in order to learn the secrets of production—the production, in both cases, of value. But neither scenario conforms to the structure of the discovery of a concealed truth—in fact, each challenges this structure directly. By looking at the specific nature of these theatrical descents, we can come to a better understanding of the task of the philosopher in both Nietzsche and Marx, as well as the distinctive position of historical knowledge within a hermeneutics of suspicion.
a, b careful: The challenge of scale invariance for comparative analyses in power law models of the streamflow recession
Authors: Dralle David , Karst Nathaniel , Thompson Sally E. 
Published: October 2015

AbstractThe falling limb of the hydrograph—the streamflow recession—is frequently well approximated by power law functions, in the form dq/dt = −aqb, so that recessions are often characterized in terms of their power law parameters (a, b). The empirical determination and interpretation of the parameter a is typically biased by the presence of a ubiquitous mathematical artifact resulting from the scale‐free properties of the power law function. This reduces the information available from recession parameter analysis and creates several heretofore unaddressed methodological “pitfalls.” This letter outlines the artifact, demonstrates its genesis, and presents an empirical rescaling method to remove artifact effects from fitted recession parameters. The rescaling process reveals underlying climatic patterns obscured in the original data and, we suggest, could maximize the information content of fitted power laws.
The implications of laser‐diffraction measurements of sediment size distributions in a river to the potential use of acoustic backscatter for sediment measurements
Authors: Agrawal Y. C. , Hanes D. M. 
Published: October 2015

AbstractWe construct vertical profiles of the acoustic attenuation and back‐scattering properties of a river column from measured particle concentration and size distribution profiles. The particle size and concentration data were collected in situ in the Cowlitz River in Washington, U.S., using a laser diffraction‐instrument LISST‐SL. The particle size distribution was bimodal, comprising a vertically well‐mixed washload, and a suspended load that was similar to Rouse profiles. We then explore how well the results of converting these synthetic profiles to recover an acoustic equivalent sediment concentration and acoustic equivalent size compare with laser data in this bimodal environment. The acoustic scattering and attenuation properties are computed for four distinct frequencies: 0.5, 1, 3, and 5 MHz. It is seen that at the lowest frequency, 500 KHz, the acoustic attenuation throughout the water column is nearly constant and determined primarily by particles of size smaller than ∼30 microns, i.e., the washload. At the next higher frequency, 1 MHz, the suspended load also contributed to attenuation, but even so, attenuation remained nearly constant over the vertical profile. Thus, at the two lower frequencies, attenuation was decoupled from scattering, making the inverse problem explicit for inversion. In contrast, at the two highest frequencies, scattering of sound by the suspended mode became the dominant contributor to attenuation, and attenuation varied by an order of magnitude over river depth. As for backscatter, the computed acoustic backscatter strength was determined by a combination of the washload and suspended sediment mode at all four frequencies. A fairly narrow monotonic relationship was found between total sediment concentration and locally computed backscatter, effectively providing a calibration between local backscatter signal strength and suspended sediment concentration. Such a relationship existed throughout the water column, for every frequency. The sediment concentration derived from backscatter at a pair of frequencies was within ∼50% of the value measured by laser diffraction; however, the acoustic equivalent diameter exceeded the laser volume mean diameter by up to an order of magnitude. The robustness of these results for application to other flow regimes or rivers remains to be investigated.
Experimental analysis of spatial correlation effects on capillary trapping of supercritical CO2 at the intermediate laboratory scale in heterogeneous porous media
Authors: Trevisan Luca , Pini Ronny , Cihan Abdullah , Birkholzer Jens T. , Zhou Quanlin , Illangasekare Tissa H. 
Published: October 2015

AbstractSeveral numerical studies have demonstrated that the heterogeneous nature of typical sedimentary formations can favorably dampen the accumulation of mobile CO2 phase underneath the caprock. Core flooding experiments have also shown that contrasts in capillary entry pressure can lead to buildup of nonwetting fluid phase (NWP) at interfaces between facies. Explicit representation of geological heterogeneity at the intermediate (cm‐to‐m) scale is a powerful approach to identify the key mechanisms that control multiphase flow dynamics in porous media. The ability to carefully control flow regime and permeability contrast at a scale that is relevant to CO2 plume dynamics in saline formations offers valuable information to understand immiscible displacement processes and provides a benchmark for mathematical models. To provide insight into the impact of capillary heterogeneity on flow dynamics and trapping efficiency of supercritical CO2 under successive drainage and imbibition conditions, we present an experimental investigation conducted in a synthetic sand reservoir. By mimicking the interplay of governing forces at reservoir conditions via application of surrogate fluids, we performed three immiscible displacement experiments to observe the entrapment of NWP in heterogeneous porous media. Capillary trapping performance is evaluated for each scenario through spatial and temporal variations of NWP saturation; for this reason we adopted X‐ray attenuation to precisely measure phase saturation throughout the flow domain and apply spatial moment analysis. The sweeping performance of two different permeability fields with comparable variance but distinct spatial correlation was compared against a homogeneous base case with equivalent mean permeability by means of spatial moment analysis.
Motion mode of poly(lactic acid) chains in film during strain‐induced crystallization
Authors: Chen Zhefeng , Zhang Shuyang , Wu Feng , Yang Wei , Liu Zhengying , Yang Mingbo 
Published: October 2015

ABSTRACTHow stress and temperature impact the movement of poly(lactic acid) (PLA) chains in the process of tensile film stretching was studied. The motion mode of chains was investigated through the study of the strain‐induced crystallization and orientation through changes in the draw temperature (Td), draw ratio, and draw rate. The crystallinity and orientation degrees of the PLA films were measured by differential scanning calorimetry, Fourier transform infrared spectroscopy, and polarized optical microscopy. According to the competition between the orientation caused by the stretching and relaxation of chains under the temperature field, the motion modes of PLA chains during strain were divided into four types, modes I–IV. When Td was 100°C, the PLA chains acted in mode I, in which the relaxation rate of chains was so fast that no crystallinity or orientation could be obtained. Beyond a draw rate of 20 mm/min at a Td of 90°C, the type of chain movement changed from mode I to II. In mode II, only crystallites could be reserved after unloading. Chains in the PLA film moved in mode III at a Td of 80°C; then, both the crystallization and orientation were enhanced monophonically with increasing draw rate. Beyond the draw rate of 10 mm/min at a Td of 70°C, the orientation rate of chains was much faster than the relaxation one, and the motion mode transformed from mode III to IV. Then, obvious decreases in the crystallinity and orientation were observed with further increases in the draw rate; this resulted from the destruction of the crystallites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42969.