bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design of Solder Connections for Self-Assembly of Optoelectronic Devices
Authors: Marinis Thomas F. , Soucy Joseph W. 
Published: December 2018

Abstract
The cost of optoelectronic assemblies is significantly higher than that of electronic assemblies due in large part to the method of assembly. A typical computer circuit board is built by screen printing solder paste onto a printed wiring board, placing components on the board at rates of several thousand per hour, and then reflowing the solder paste in a conveyor oven. By contrast, optoelectronic assemblies are built up in a sequential process in which epoxy is dispensed for a single component, which is placed and held in position until the epoxy is cured. Many minutes are required to build an optoelectronic assembly, such as a laser module, by this approach, also the precision robotic placement tool needed for this process costs in excess of a million dollars. The demand for all types of optoelectronic components in communications, computing, automotive, medical and aerospace applications is great, but the high cost of manufacture is constraining growth, so clearly a better method of assembly is needed.
In surface mount assembly, advantage is taken of the high surface tension of molten solder to self-align ball grid array packages and flip chip die. However, in these applications, the volume of solder applied as paste by stencil printing is not sufficiently well controlled to achieve the precise alignment required for optoelectronic devices. We believe that the requirement on solder volume control for assembly of optoelectronic devices can be relaxed by designing the bond pads so that the height or alignment of connections is controlled by surface tension of the solder rather than its volume. Our design approach to accomplishing this is to connect auxiliary pads to the primary attachment pad, which act as solder reservoirs. Surface tension causes solder to be redistributed among these pads to achieve a uniform pressure throughout the solder volume. This phenomena is governed by the Young-Laplace equation, ΔP = γκ, in which ΔP represents the difference in pressure within and outside the solder, γ the surface tension of the solder and κ the local curvature of the solder surface. Thus, the design of the set of primary and auxiliary pads is critically important to realizing the desired control of joint height. In this paper we describe the use of the Surface Evolver software package in combination with analytical models, to analyze the behavior of various connection configurations with respect to variations in printed solder volume. Specifically, we calculate the equilibrium shape of the solder surface over the connected set of pads and examine how control of joint height is affected by the number, size and geometry of auxiliary pad configurations. We also discuss results from some preliminary experiments that we are conducting to validate our modeling results.
Highly Reliable Solderless Contact with Press-fit Technology for Power Modules
Authors: Egusa Minoru , Ishibashi Hidetoshi , Otsubo Yoshitaka , Kikuchi Masao , Kashiba Yoshihiro 
Published: December 2018

Abstract
Press-fit technology has been expected as a mounting technique instead of soldering in power electronics. To apply press-fit technology to power modules, the basic behavior of the contact resistance and an interface reaction of the press-fit contact are studied. Further, maintaining a stable contact force is important to maintain a low contact resistance. Factors that reduce the contact force include the displacement by the geometric tolerance of the pin and through-hole of the printed circuit board, and the thermal cycle load. We solved the problem by designing a new press-fit pin structure that provides the constricted portion for the body part of the press-fit pin, and clarified by thermal cycle test on power modules.
Implementation of a Temperature Ramp Rate Requirement and Impact on the Packaging Processes
Authors: Hamm Randy , Whitlock Daren , Eatinger Ryan , Stearns Jeremy , Ringwood Samuel 
Published: December 2018

Abstract
This paper addresses implementation of a heating and cooling temperature ramp rate requirement and its impact on packaging processes. A complex multi-chip module packaging design includes a printed wiring board, solder attachment of a AlSiC-9 back plate, solder attachment of a multi-room seal frame, soldered surface mount components, power die soldered directly to a heat sink, epoxy attached chip-and-wire die, a welded lid and ribbon cable. Because of complex material interactions that exist in the design, concerns arose about cracking and other thermally induced damage that might occur during temperature excursions. The assembly challenge that resulted was a product requirement to limit the heating and cooling temperature ramp rates during packaging processes. Working together, the design agency and production agency ultimately came to an agreement on what the temperature ramp rate requirement should be and how to qualify the processes and the periodic determination of compliance.
The requirement was implemented on all packaging processes that saw a heating and cooling cycle. Epoxy cure after die attach and wire bonding were modified most significantly and are specifically addressed in this paper. Solutions were implemented to minimize impact to assembly flowtime and to minimize the chance of processing errors. Temperature profiles had the ramp rates calculated then documented and qualified based on the process parameters (set point temperatures and dwell times) and the assembly machines, ovens, hot plates and tooling used. Compliance is proved through thermal profiling and calculation of ramp rate. Deviation from the set process will require approval from the design agency.
Analysis of Ultrasonic Welding of Mechanically Coupled Small Area Contacts for a Silicon Carbide Power Module
Authors: Saxena Kuldeep , Hays Aryn , Kao Ivan , Cole Zach 
Published: December 2018

Abstract
In this paper, the shear strength of small-area welded contacts was optimized. Using design of experiments (DoE) optimization techniques, copper power contacts with 4 mm2 feet were welded to both copper and nickel/gold-plated copper substrates where pressure, amplitude and deformation were the control factors. For the DoE, the setting combinations were chosen based on the concept of classical Screening Design. This design was best suited because it allowed an elementary exploration of interaction relationships for a wide range of factors. The pressure was varied from 1.4 to 1.8 bar, the amplitude from 90 to 100%, and the deformation from 0.06 to 0.1 mm. These limits were chosen based on prior welding experience with the equipment and similar parts. Each bond was optically inspected to confirm high-quality bonds. Using common shear techniques, over 200 bonds were sheared; strengths were recorded as the DoE dependent variable.
The initial step found that pressure was the most significant factor. Pressure and deformation were also proven to affect strength inversely to each other. Interestingly, the planarity of the contacts had no measurable effect on the welding strength. Consistent bond strengths were achieved regardless of the bonds' place within the established bond order. For both copper-to-copper and copper-to-nickel/gold-plated bonds, the optimal settings were: pressure at 1.8 bar, amplitude at 90%, and deformation of 0.1 mm, while achieving shear strengths of 40.5 kgf and 39.1 kgf, respectively. This doubled the previous benchmark weld strengths.
A New Method for Non-Destructive Characterization of Through Holes in Printed Circuit Boards
Authors: Czaplewski Sarah , Doman Joe , Kuczynski Joe 
Published: December 2018

Abstract
Plated through hole (PTH) quality, including plating roughness, is a critical factor in the manufacture of reliable printed circuit boards (PCBs). Currently, cross-sectioning is most commonly used to assess PTH roughness but sectioning is a destructive process and offers a limited view of the PTH. Therefore, a non-destructive casting method using a silicone elastomer was developed to evaluate PTH roughness. Castings were successfully created from PTHs with aspect ratios as high as 22:1 and the castings accurately replicated the microtopography of the plating. Laser scanning microscopy was used to quantitatively measure the surface roughness of the castings which was shown to correlate to current induced thermal cycling (CITC) coupon cycles to failure, a measurement of PTH reliability. Thus, the casting technique can be used to quickly assess PTH quality and its effect on reliability. In addition to plating roughness, it was demonstrated that the casting technique can be used to evaluate back drill quality, PTH diameter along the length of the barrel, as well as drill and desmear processes by casting non-plated through holes.
Microstructure and Mechanical Properties of Pressureless Sintered Silver Die-attach Materials
Authors: Watanabe Tomofumi , Tanaka Keisuke , Takesue Masafumi 
Published: December 2018

Abstract
Microstructural and mechanical properties of a pressureless sintered silver material were measured. The Microstructure of the pressureless sintered silver material had pores of less than 1 μm in size and some silver matrices sintered with nanoparticles between each other. The pressureless sintered silver material could be bonded on bare copper without applying an external pressure. After subjecting the material to a high temperature exposure test at 250 °C and for 1000 h, it showed no substantial change in microstructure and showed a constant Young's modulus of 14 GPa. The pressureless sintered silver material in this work did not show any embrittlement or increase in pore size after the high temperature exposure test, which demonstrated that the material has reliable physical and mechanical properties at temperatures up to 250 °C.
Development of High Temperature Tantalum Polymer Capacitors
Authors: Chacko Antony P. , Chen James , Stolarski Chris , MotaCaetano Cristina , Lessner Philip 
Published: December 2018

Abstract
This paper focuses on the development of new 150°C capable surface mount polymer tantalum capacitors and the enabling technologies. The conductivity stability of the conducting polymers at high temperatures as well as the equivalent series resistance (ESR) stability of the polymer tantalum capacitors at these temperatures were investigated in this study. Analysis of the oxygen permeation paths causing polymer oxidation and materials solutions for preventing oxygen permeation and polymer oxidation are described. The development of new cathode and protective coating material technology is presented. Their effectiveness in providing high temperature ESR stability is demonstrated by high temperature life test at 150°C of polymer capacitors.
Explore High Bonding Reliability of Cu Wire Bonded Devices under Extreme Halide Contaminated Environments
Authors: Asokan Muthappan , Caperton Joshua , Salunke Ashish , Chyan Oliver , Xu Fei 
Published: December 2018

Abstract
Copper has rapidly replaced gold as the preferred wire bonding material in microelectronic packaging due to its lower cost and many performance advantages. However, halides induced corrosion-related failures need to be carefully controlled to ensure maximum bonding reliability. Literature reported corrosion studies mostly focus on intermetallic compounds as the corrosion vulnerability. Utilizing a novel corrosion screening approach, we established that the bimetallic contact between Cu balls and Al bond pad is the real driver for the observed heavy Al pad corrosion induced by chloride ions [1]. We identified, for the first time, H2 evolution was the coupling cathodic half reaction to the Al bond pad corrosion. With these improved mechanistic insights, we developed an effective corrosion inhibition strategy that utilizes chemical vapor deposition to selectively bond corrosion inhibitors to these critical Cu ball/Al pad interfaces. A new corrosion-screening platform was developed to evaluate the effectiveness of this inhibitor protection treatment. After intentionally loaded chloride contaminants on the die surface, the molded Cu wire bonded devices with selected inhibitor treatment were subjected to PCT stress tests. The subsequent failure analyses, showed selected inhibitor treatment is highly effective of preventing Al bond pad corrosion even under the massive attack of heavy Cl− ion contamination and extensive delamination.
Electrical Characterization of Low Temperature PECVD Oxides for TSV Applications
Authors: Mackowiak Piotr , Abdallah Rachid , Wilke Martin , Patel Jash , Ashraf Huma , Buchanan Keith , Lang Klaus-Dieter , Schneider-Ramelow Martin , Ngo Ha-Duong 
Published: December 2018

Abstract
In the present work we investigate the quality of low temperature Plasma Enhanced Chemical Vapor Deposition (PECVD) and plasma treated Tetraethyl orthosilicate (TEOS)-based TSV-liner films. Different designs of Trough Silicon Via (TSV) Test structures with 10μm and 20μm width and a depth of 100μm have been fabricated. Two differently doped silicon substrates have been used – highly p-doped and moderately doped. The results for break-through, resistivity and capacitance for the 20μm structures show a better performance compared to the 10μm structures. This is mainly due to increased liner thickness in the reduced aspect ratio case. Lower interface traps and oxide charge densities have been observed in the C-V measurements results for the 10μm structures.
High Performance EMI Shielding Materials and Spraying Process Parameters for High Frequency FCBGA Application
Authors: Joo Kisu , Lee Kyu Jae , Hwang Jung Woo , Yoon Jin-Ho , Kim Yoon-Hyun , Jeong Se Young 
Published: December 2018

Abstract
We studied and demonstrated high-performance Ag epoxy composites. A variety of shaped Ag particles were teste to optimize the electrical properties and mechanical reliability. The resulting Ag epoxy composites containing flake-shaped Ag particles showed less than 5×10−7Ω·m electrical conductivity and about 20mΩ series-resistance of PKG daisy chain, which directly corresponded to the excellent shield effectiveness. The shield effectiveness of resulting EMI shielding layer made of Ag and matrix is as high as 60dB, 65dB, 70dB at 5um, 10um, 20um-thick film, respectively by ASTM standard. We studied that how various factors, such as curing temperature, Ag contents, and film thickness, effects the electrical properties of shielding material and FCBGA package. It was found that the resistivity of conductive shielding material and the series-resistance were affected by the curing temperature than the curing time. Additionally, we demonstrated the electrical properties of AgCu epoxy composites.
Laparoscopy for evaluation of infertility patients in a tertiary center in north-eastern Nigeria
Authors: Aminu Muhammad B. , Datttijo Lamaran M. , Kadas Saidu A. , Shehu Abubakar M. , Chama Calvin M. 
Published: December 2018

Laparoscopy uses fiber optic endoscope passed through the abdominal wall to visualize the peritoneal cavity for both diagnosis and therapy; it is also referred to as Minimal Access Surgery. It is an important tool in the evaluation of infertility. The objective of this study is to determine the value of laparoscopy for evaluation and treatment of infertility patients in Bauchi. North east, Nigeria. This is a retrospective cross-sectional study of women who had evaluation using laparoscopy. The case files and theatre records of all the women who had laparoscopy over a 5-year period between the 21st February, 2012 and 20th January, 2017 were retrieved and analyzed. Data on age, parity, type of infertility, intra operative findings and type of procedures done were extracted using a proforma. Analysis was done using statistical package for social sciences (SPSS version 21, IBM). One hundred and thirty-seven women had laparoscopy and or hysteroscopy during the review period, retrieval rate was 98%. Mean age was 29 years ±SD. Median number of pregnancies was 2. Most of the women had laparoscopy for secondary infertility indicated by tubal or an ovarian factor. Thirty-two (32) women (23.4%) had normal study. Sixteen (16) interventional procedures (12%) were done during the study period ranging from ovarian cystectomy, adhesiolysis, salpingectomy and sterilization. There were nine (9) congenital abnormalities detected during the period. Fifteen (15) women had both hysteroscopy and laparoscopy. Three women (2.8%) had uterine perforation with only one converted to laparotomy giving an overall success of 97%. Laparoscopy has changed the perception of many gynecologists in the diagnosis and treatment of infertility from mere imaginative to definitive thoughts.
Em diversas frentes: as filhas da caridade e suas experiências educacionais nas províncias de Minas Gerais e do Rio De Janeiro (1850-1900)
Authors: Pasche Aline de Morais Limeira , Arruda Maria Aparecida 
Published: December 2018

Ao entender a importância de refletir acerca das articulações entre poder público e Igreja Católica ao longo do desenvolvimento do processo de escolarização no Brasil, o estudo investigou experiências educativas de iniciativas religiosas de uma Ordem específica em atuação desde a segunda metade do século XIX. Neste caso, propusemos a análise acerca do papel das Filhas da Caridade (Ordem de São Vicente de Paulo) no campo da Educação, a partir de algumas orientações mundiais da Ordem, cuja atuação se realizava em diversos países. Os Estatutos da Ordem de São Vicente de Paulo pretendiam regulamentar suas práticas, elaborando um complexo sistema de regras, princípios, finalidades e normatizações. Assim, procuramos esquadrinhar a proposta de atendimento das religiosas, e as representações erigidas em torno da ação educativa, com base nos pressupostos especificados naquele documento e nas demais fontes analisadas (anúncios publicitários, relatórios oficiais da administração do ensino, impressos). De modo específico, tencionamos inquirir acerca de suas ações nas províncias de Minas Gerais e Rio de Janeiro. Tomamos para efeito da análise, dois exemplos de instituições educativas criadas pelas vicentinas, pertencentes à malha privada do ensino: em Minas Gerais, um Externato (com aulas avulsas) na cidade de São João del Rei; na província do Rio de Janeiro, o Colégio Imaculada Conceição na Corte Imperial, fundado em 1855 (em funcionamento até hoje). Como resultado, apreendemos que, apesar de distantes geograficamente, as instituições analisadas apresentam maior número de características que as aproximam num esforço pelo investimento comum da educação. Palavras-chave: instituições escolares, ensino religioso, expansão das ordens religiosas.
Los misiles chinos: Crónica de un desarme
Authors: Tellería Escobar Loreta 
Published: December 2018

El presente trabajo describe, en formato de crónica, los principales acontecimientos sucedidos en el denominado caso de los “misiles chinos”. Es decir, la entrega, para su desmantelamiento, de los únicos misiles con los que contaba Bolivia como mecanismo de defensa antiaérea, a personal militar del gobierno de Estados Unidos. El hecho sucedió meses antes de las elecciones generales de diciembre de 2005, en las cuales Evo Morales obtuvo la presidencia, y después de un largo proceso de crisis e inestabilidad política en el país (2003-2005). Así mismo, se identifican las principales evidencias y consecuencias políticas e institucionales de la subordinación militar a una potencia extranjera, todas ellas permeadas por aspectos tales como injerencia, pérdida de soberanía e impunidad.
Pablo Estefanoni. Los inconformistas del centenario: Intelectuales, socialismo y nación en una Bolivia en crisis (1925-1939). 384 páginas. La Paz: Plural Editores, 2015.
Authors: Cunha Filho Clayton Mendonça 
Published: December 2018

Pablo Estefanoni. Los inconformistas del centenario: Intelectuales, socialismo y nación en una Bolivia en crisis (1925-1939). 384 páginas. La Paz: Plural Editores, 2015.
Stephen C. Cote. Oil and Nation: A History of Bolivia’s Petroleum Sector. xxiii, 225 pages. Morgantown: West Virginia University Press, 2016.
Authors: Anaya Giorgis Juan José 
Published: December 2018

Stephen C. Cote. Oil and Nation: A History of Bolivia’s Petroleum Sector. xxiii, 225 pages. Morgantown: West Virginia University Press, 2016.
História fotografada, história (com)partilhada: imagens e vozes de Cotia
Authors: Chaves Nunes Sandra Regina 
Published: December 2018

Resumo Esse artigo discorrerá sobre os caminhos – teóricos ou não –condutores à construção do blog – álbum – do cotidiano demoradores da cidade de Cotia: História Fotografada, História(Com)Partilhada . O blog surge do desejo de experimentaçãode novas metodologias para o ensino da linguagem populare culta, da narração pela palavra e pela imagem, e centra-seem fragmentos narrados da história de fotografias escolhidas pelos personagens centrais do momento capturado porelas. Esses fragmentos fazem parte de textos transcritose transcriados pelos alunos de Comunicação e Expressãodos Cursos de Gestão Empresarial e Gestão da ProduçãoIndustrial da Fatec Cotia.
Between the Desire for Law and the Law of Desire: #MeToo and the Cost of Telling the Truth Today
Authors: Burgess Sarah K. 
Published: December 2018

ABSTRACT
This article examines the kairotic beginnings of the #MeToo movement in order to understand what we are to make of this moment. It shows that commentaries about #MeToo unfold as a debate over the desire for law and the law of desire, ceding the contingent kairotic moment in which we might remake our contemporary political landscapes. As such, I argue that movements dedicated to ending sexual violence must reimagine the scene of address in which demands for justice might be spoken and their speech recognized as the truth. This project is complicated, however, by a post-truth era in which telling the truth matters little because truth itself has been devalued. Through this lens, we can see that the cost of telling the truth in the terms of the established debate is the creation of a form of identity politics that reinforces post-truth logics rather than intervening in them.
On the Erosion of Democracy by Truth
Authors: Vivian Bradford 
Published: December 2018

ABSTRACT
This article proposes a counterintuitive approach to the timely phenomenon of so-called post-truth politics. The article argues that the premise of a post-truth politics misdiagnoses the particular crisis of truth that now threatens to undermine democratic norms and institutions. Social and political appeals cited as prime examples of an allegedly proliferating “post-truth” mentality do not abandon truth; those appeals rationalize available forms of truth conducive to the legitimation of authoritarian power. They do so, the article maintains, by simultaneously undermining opportunities for pluralistic deliberation over conditions of truth itself and promoting extra-deliberative versions of truth (based on biological supremacy, historical destiny, or cultural heritage). In supporting these claims, the analysis shows how the spread of particular forms of truth (not the simple loss of it) can erode democracies from within and, concomitantly, how authoritarian regimes may be invested in a regime of truth as much as any other sociopolitical system.
Novel compounding and the emergence of structure in two young sign languages
Authors: Tkachman Oksana , Meir Irit 
Published: December 2018

This paper investigates how structure emerges in a young language, focusing on compounding in two young sign languages, Israeli Sign Language (ISL) and Al-Sayyid Bedouin Sign Language (ABSL). We focus on novel compounds (tokens invented on the spot) to ensure that we are studying a productive process and to avoid issues contingent with lexicalization. We found that both languages make use both of compounding and size-and-shape classifier constructions (SASS-constructions), but ISL and ABSL have conventionalized different structures and the structures they do use are conventionalized to different degrees. We discuss the similarities and differences of those constructions in ISL and ABSL in the context of structure emergence and language evolution.