DOCSLIB.ORG

5-Cg-2015-010694R2-With Cover

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
5-Cg-2015-010694R2-With Cover Page 1 of 16 Crystal Growth & Design 1 2 3 4 Kinetics of the β→α transformation of tin: Role of α–tin 5 6 nucleation 7 8 9 10 11 Guang Zeng1, Stuart D. McDonald1, Qinfen Gu2, Syo Matsumura3 and Kazuhiro Nogita1* 12 13 14 15 1 Nihon Superior Centre for the Manufacture of Electronic Materials (NS CMEM), School of 16 17 Mechanical and Mining Engineering, The University of Queensland, St Lucia, QLD 4072, 18 19 Australia; 20 21 22 2 Powder Diffraction Beamline, The Australian Synchrotron, Clayton, VIC 3168, Australia; 23 24 3 Department of Nuclear Engineering and Quantum Physics, Kyushu University, Fukuoka 819- 25 26 0395, Japan 27 28 29 30 31 ABSTRACT The role of α-Sn nucleation on the kinetics of the β→α phase transformation is investigated in this 32 study, using in situ variable temperature synchrotron powder x-ray diffraction (PXRD). In the entire thermal history 33 34 of α→β→α transformation, the population of α-Sn at the onset of the β→α transformation was varied by controlling 35 the α→β transformation under isothermal conditions. The degree of α-Sn nucleation is found to have a strong 36 37 influence on the kinetics of the β→α phase transformation. By introducing an impingement factor c=2, the 38 transformation curves yield good fits to the modified Johnson-Mehl-Avrami-Kolmogorov (JMAK) model. Inceases 39 40 in annealing time at 45 ºC resulted in insufficient nucleation at the commencement of the reaction at the kinetically 41 optimal temperature of -45 ºC and additional nucleation is required. 42 43 44 45 46 1. Introduction 47 48 The crystallography, mechanical properties and physical properties of tin have been the subjects 49 1-5 50 of considerable interest from experimental and calculation/modeling studies . The β→α 51 transformation in tin has been of great theoretical and practical interest for over 100 years 2, 3, 5-14. 52 53 It is the only known solid-state transformation in which a metallic material (β-Sn) transforms 54 12-15 55 into a non-metallic semi-conductive solid (α-Sn) . The significant density change (27.0% at - 56 5, 14 57 100°C to 26.1% at 50°C) that is induced by this transformation can lead to the blistering of 58 59 60 ACS Paragon Plus Environment 1 Crystal Growth & Design Page 2 of 16 1 2 3 the free surface of the tin, cracking and even complete disintegration. This phenomenon has been 4 5 traditionally known as “tin pest” 5 because the blisters that form on the surface of the tin have an 6 7 appearance similar to those which occur on the skin of animals and humans afflicted by some 8 14 9 diseases . This blistering and cracking is the result of the combination of the large increase in 10 14, 16 11 volume as the β-Sn transforms to α-Sn and the very low ductility of the α-Sn . With the 12 widespread adoption of lead-free solders by the electronics industry there has been renewed 13 14 interest in tin pest because of concern that these Sn-rich alloys might be susceptible to this 15 14 16 phenomenon . It has been concluded that commercial lead-free solder made with standard purity 17 5, 17 18 Sn have less potential for "tin pest" than high purity Sn due to impurity effects . However, it is 19 still difficult to predict "tin pest" and the deep understanding required to exercise any practical 20 21 control of the β→α transformation is lacking5. 22 23 Previous studies have confirmed that the β→α transformation is a nucleation and growth process 24 25 2, 5, 18. The equilibrium transformation temperature is 13.2°C but in practice the reaction occurs 26 27 only with significant undercooling and after a considerable incubation period2, 3, 6, 10, 13. The 28 13 29 nucleation of α-Sn is particularly difficult so the majority of the time for the β→α 30 31 transformation is taken up by the incubation period with the subsequent growth being relatively 32 rapid 5. It has been reported that the kinetics of the transformation can be greatly accelerated by 33 34 the introduction of heterogeneous nuclei, known as seeding 13. Seeding can be achieved by 35 36 pressing into the β-Sn, powdered crystals of α-Sn or other crystals that are isomorphic with α-Sn 37 6, 13 38 with similar lattice parameters such as CdTe, InSb and Ge . Once nucleated the growth 39 kinetics of the β→α transformation are determined mainly by the impurities and alloying 40 41 additions in the tin, the shape and size of the sample, the tin grain size, the temperature and the 42 43 thermo mechanical history prior to transformation 5, 9-11, 19-23. The kinetics of the β→α 44 5 24 45 transformation have been intensively investigated by methods such as XRD , DSC , 46 2 9 8-12, 19-26 47 dilatometry , electrical resistance measurement and microstructural observation . 48 Despite these investigations over the past 60 years the kinetics of the transformation are still not 49 50 well understood, and this may be due to the difficulty in identifying the quantity of any α-Sn 51 52 particles within the β-Sn as potential nucleation sites for the transformation. 53 54 X-ray powder diffraction is one of most powerful methods of obtaining quantitative phase 55 27 56 information from multicomponent mixtures . The variable temperature in situ synchrotron 57 58 PXRD that is now available provides a method of studying the transformation more precisely 59 60 ACS Paragon Plus Environment 2 Page 3 of 16 Crystal Growth & Design 1 2 3 than has been possible in the past. In our recent study of the transformation using this method, 4 5 data sufficient to plot a temperature, time, transformation (TTT) diagram for the β→α 6 7 transformation were obtained 5. This TTT diagram has a typical “C” shape with a “nose” at - 8 9 50°C and is reasonably consistent with the results of the 1957 kinetic study by Burgers and 10 2 11 Groen who used dilatometry. In that study the samples were of similar purity (99.99%) and had 12 a thermal history of previous β→α transformations. It should be noted that in our study where 13 14 samples were annealed for 10 minutes at 50°C prior to cooling, the β→α transformation kinetics 15 28-30 16 were a good fit with the Johnson-Mehl-Avrami-Komolgorov (JMAK) model with an Avrami 17 18 exponent of 3, which implies that the transformation occurred by three-dimensional growth from 19 pre-existing nuclei5. However, as the annealing time at 50°C was increased to 20 minutes, the 20 21 kinetics failed to fit the JMAK equation and additional nucleation was required for the β→α 22 17 23 transformation to commence . In our recent study, additions of 1 wt.% Pb, Cu, Ge, or Si, in the 24 17 25 form of powder mixtures, all inhibited the β⟶α transformation . The method used minimised 26 27 the effects of element solubility and residual stresses and the primary effect of the additive was 28 assumed to be that of intimate physical contact. Of the addition elements studied, Pb and Cu 29 30 show the strongest ability to suppress the β⟶α transition. Ge and Si also inhibited the β→α 31 17 32 transformation despite having a similar crystal structure to α-Sn . The kinetics of the β→α 33 4-6, 17 34 transformation is largely determined by the nucleation of α-Sn . The presence of pre-existing 35 α-Sn has been proven to greatly accelerate the formation and growth of the α-Sn phase from β- 36 37 Sn. However, it has not been quantitatively or accurately investigated in previous studies. In this 38 39 study, high purity α-Sn samples were in situ annealed during powder diffraction at 45°C for 40 41 various durations, aiming to control the amount of α-Sn remaining after α⟶β transformations of 42 43 varying degrees of completeness. Afterwards, the influences of α-Sn nucleation on the β⟶α 44 transformation in tin were examined. 45 46 47 2. Experimental Section 48 49 To prepare α-Sn samples for powder XRD experiments, high purity 99.99% tin cylinders (20mm 50 51 diameter and 10mm height) were cast and then kept for 180 days at -45ºC. During this time, the 52 cylinders converted to α-Sn powder. The samples used in this study are identical to those used in 53 54 previous studies5, 31. 55 56 57 58 59 60 ACS Paragon Plus Environment 3 Crystal Growth & Design Page 4 of 16 1 2 3 Samples of ~0.15g of the powder mixtures were loaded into quartz capillaries (0.3 mm in 4 5 diameter) and stored at -20 ºC in preparation for experiments at the the Powder Diffraction 6 7 beamline at the Australian Synchrotron. During powder x-ray diffraction (PXRD), the 8 9 temperature of the samples was controlled using a Cryostream (Oxford Cryosystems, Cryostream 10 11 Plus) with temperature accuracy within +/- 0.5 ºC. High-resolution PXRD data were collected in 12 the 2 theta range of 10 to 80 degrees using a Mythen-II detector with a 18 keV beam. A LaB6 13 14 standard (NISTLaB6 660b) was used at room temperature for wavelength calibration. The 15 16 calibrated wavelength was 0.6887 Å. Differential Scanning Calorimetry (DSC) study at a heating 17 18 rate of 6ºC/min indicated that 46.7 % of α-Sn was transformed to β-Sn at the point of 45ºC 19 during continuous linear heating, as shown in Figure 1a 17.
Load more

Recommended publications
  • Auction V Iewing
    AN AUCTION OF Commemorative Medals and Numismatic Books The Richmond Suite (Lower Ground Floor) The Washington Hotel 5 Curzon Street Mayfair London W1J 5HE Wednesday 30 May 2012 12:00 Free Online Bidding Service www.dnw.co.uk AUCTION Weekdays, Monday 21 May to Friday 25 May 16 Bolton Street, Mayfair, London W1 strictly by appointment only Monday 28 May and Tuesday 29 May 16 Bolton Street, Mayfair, London W1 Public viewing, 10:00 to 17:00 Wednesday 30 May 16 Bolton Street, Mayfair, London W1 Public viewing, 08:00 to end of the Sale Appointments to view: 020 7016 1700 or auctions @dnw.co.uk VIEWING Catalogued by Christopher Webb, Jim Brown and A.N. Other Photography by Ian Kington In sending commissions or making enquiries please contact Christopher Webb or Jim Brown Catalogue price £15 C ONTENTS Please note: The auction will take place in one session, starting at 12.00 British Medals from the Collection of James Spencer........................................................................1-159 British Medals from other properties............................................................................................160-280 Medals of Cuba from the Collection of the late Edward Roehrs....................................................281-353 Russian Medals from an Old Collection, the property of a Lady ..................................................354-380 World Medals from other properties .............................................................................................381-450 British and World Medals – Lots ...................................................................................................451-506
    [Show full text]
  • THE DEGRADATION of PEWTER in ANTIQUE LACE BOBBINS Home Page
    THE DEGRADATION OF PEWTER IN ANTIQUE LACE BOBBINS Home Page Parent Page THE DEGRADATION OF PEWTER IN ANTIQUE LACE BOBBINS. This article needs a couple of pics. Pewter Degradation Introduction The pewter used in bobbins is one of the prettiest decorative processes that makers used. Unfortunately during the passage of time much of the pewter by some makers has degraded and has either fallen off the bobbin or has become swollen, misshapen and even crumbly. The following is my attempt, with the help of many people on the web and especially my friend Neil Keats, to explain this phenomenon. Pewter. Pewter is an alloy (i.e. a mixture) of tin and lead. The better the quality of pewter the higher the percentage of tin is in the alloy. Tin exists in three forms, depending on the temperature. This is called polymorphism (poly-many, morphism-shapes). At temperatures between 13 and 160 degrees C, it is called White tin, and the atoms (think of them as little balls in this description) are packed closely together to form the metal. Hence, it is a dense metal, i.e. it is hard. file:///C|/Documents%20and%20Settings/My%20Docu...s/Pewter%20degredation/Pewter%20degredation.htm (1 of 4) [6/9/2003 8:15:25 PM] THE DEGRADATION OF PEWTER IN ANTIQUE LACE BOBBINS Below 13 degrees C the atoms rearrange to become more loosely packed (actually in the same configuration as diamond). This shows first as wart-like structures on the surface, and eventually leads to the tin crumbling into a powder. This is called "tin pest", and is what happened to the buttons on Napoleon's soldiers coats.
    [Show full text]
  • Technical Specifications, Technical Reports, Publicly Available Specifications (PAS) and Guides (Hereafter Referred to As “IEC Publication(S)”)
    This is a preview - click here to buy the full publication IEC/TS 62647-22 ® Edition 1.0 2013-09 TECHNICAL SPECIFICATION Process management for avionics – Aerospace and defence electronic systems containing lead-free solder – Part 22: Technical guidelines INTERNATIONAL ELECTROTECHNICAL COMMISSION PRICE CODE XB ICS 03.100.50; 31.020; 49.060 ISBN 978-2-8322-1112-0 Warning! Make sure that you obtained this publication from an authorized distributor. ® Registered trademark of the International Electrotechnical Commission This is a preview - click here to buy the full publication – 2 – TS 62647-22 IEC:2013(E) CONTENTS FOREWORD ........................................................................................................................... 5 INTRODUCTION ..................................................................................................................... 7 1 Scope .............................................................................................................................. 9 2 Normative references ...................................................................................................... 9 3 Terms, definitions and abbreviations ............................................................................. 10 3.1 Terms and definitions ....................................................................................... 10 3.2 Abbreviations ................................................................................................... 15 4 Approach ......................................................................................................................
    [Show full text]
  • SMT Magazine, July 2014
    Since the EU passed the Restriction of Hazardous Substances directive in 2006, tin whiskers have become a serious threat to the assembly of PCBs. This month, our feature contributors Dr. Jennie Hwang, Andrzej Czerwinski, and Linda Woody tackle this prickly subject. 16 Tin Whiskers: Capsulization 30 Whisker Growth in Tin Alloys by Dr. Jennie S. Hwang on Glass-Epoxy Laminate by A. Czerwinski, A. Skwarek, M. Płuska, J. Ratajczak and K. Witek 40 Tin Whisker Risk Management by Conformal Coating by Linda Woody and William Fox 4 SMT Magazine • July 2014 JULy 2014 EnginEERing voLUME 29 SoLUTionS nUMBER 7 foR PCB www.smtmagazine.com MAnUfACTURing CONTENTS ARTICLE VIDEO INTERVIEWS 76 Meeting Future Stencil Printing 15 Major Changes in the Challenges with Ultrafine Last Eight Decades Powder Solder Pastes by Edward Briggs 66 A Glimpse of the Future COLUMNS 8 Electronic Assembly with Solder: an Unblinking Look at 73 DEK Deals with Automotive “The Devil We Know” Device Miniaturization by Joe Fjelstad 62 DFARS Flow Downs and Trusted Suppliers by Todd Kramer 70 More Stencil Questions (and the Answers!) by Rachel Miller-Short SHORT 88 Efficient Thermal NEWS HIGHLIGHTS Cooling and 60 Mil/Aero Heating 68 Market EXTRAS 74 Supplier/New Product 92 Events Calendar 90 SMTonline 93 Advertiser Index & Masthead 6 SMT Magazine • July 2014 gUEST CoLUMn ELECTRONIC INTERCONNECTIONS Electronic Assembly with Solder: an Unblinking Look at “The Devil We Know” by Joe Fjelstad vERDAnT ELECTRoniCS Solder is unquestionably highly practical ing electronic assemblies of every sort. The only technology for joining metals, and carries with fly in the ointment is that the EU parliament, it a long history.
    [Show full text]
  • Stannides and Intermetallic Tin Compounds – Fundamentals and Applications
    Stannides and Intermetallic Tin Compounds – Fundamentals and Applications Rainer P¨ottgen Institut f¨ur Anorganische und Analytische Chemie, Westf¨alische Wilhelms-Universit¨at M¨unster, Corrensstraße 30, D-48149 M¨unster, Germany Reprint requests to R. P¨ottgen. E-mail: [email protected] Z. Naturforsch. 61b, 677 – 698 (2006); received January 19, 2006 Dedicated to Professor Wolfgang Jeitschko on the occasion of his 70th birthday Tin, tin alloys and intermetallic tin compounds play a key role in many technologies and high-tech applications. Many of these intermetallics find application in daily life such as pewterware, bronzes, solders, fusible alloys, superconductors, capsules for wine bottles or tinplate packaging. Many of the applications are directly related to distinct stannides or intermetallic tin compounds. The crystal chemistry and chemical bonding of these materials as well as their applications are briefly reviewed. Key words: Tin, Stannides, Intermetallics Introduction Elemental tin is a fascinating element which has two modifications under ambient pressure conditions. At 13.2 ◦C the tetragonal metallic β-modification (space 3 group I41/amd, ρ = 7.285 g/cm ) transforms to the semi-metallic α-modification with the cubic diamond structure (space group Fd3¯m, ρ = 5.769 g/cm3) [1, 2]. This phase transition proceeds via a translationen- gleiche symmetry reduction [3] and usually proceeds slowly. However, if small nuclei of the α-modification have formed, the transformation proceeds rather fast and destroys the metallic workpiece (tin pest). The two modifications have different near-neighbor coordina- tion. In α-Sn each tin atom has a tetrahedral coordi- nation at a Sn–Sn distance of 281 pm, while the coor- dination number in β-Sn is increased to 4 × 302 + 2 × Fig.
    [Show full text]
  • Tin Pest: a Forgotten Issue in the Field of Applied Superconductivity?
    correspondence Tin Pest: A Forgotten Issue in the Field of Applied Superconductivity? To the Editor — In the framework of Averaged results obtained from solders operating below 286 K. But the hybrid magnet project aiming to shear tests performed on the twelve even with a high concentration of lead produce 43 T in a 34 mm warm aperture dedicated samples are summarized such as in Sn63Pb37, tin pest can also at LNCMI-Grenoble, a novel type of in Fig. 1. A clear difference of the appear on long term8 restricting the superconducting conductor is being thermo-mechanical behavior between choice to tin-free solder alloys for high developed in collaboration with CEA- Sn96Ag4 and Sn60Pb40 samples tested reliability interconnects working at Saclay. It is based on the soft soldering at 300 K and 77 K can be observed. The cryogenic temperature. of a Nb-Ti flat Rutherford cable on a rupture shear strength of Sn96Ag4 Even if it is still unproven but not Cu-Ag hollow stabilizer that will be soldered samples decreases in average impossible that tin pest has destroyed cooled by superfluid helium i.e. a by 12.9 MPa at low temperature (-37 %) the buttons of uniforms of Napoleon’s Rutherford Cable on Conduit Conductor whereas for Sn60Pb40 ones an average army during its disastrous retreat from (RCOCC)1. During the study and the increase of 8.5 MPa is observed (+28 Russia in 1812, this problem is real and qualification of the soft soldering %). It can be added that the rupture known for a few hundreds of years.
    [Show full text]
  • YHT Cover.Qxd
    PD IEC/TS 62647-22:2013 BSI Standards Publication Process management for avionics — Aerospace and defence electronic systems containing lead-free solder Part 22: Technical guidelines PD IEC/TS 62647-22:2013 PUBLISHED DOCUMENT National foreword This Published Document is the UK implementation of IEC/TS 62647-22:2013. The UK participation in its preparation was entrusted to Technical Committee GEL/107, Process management for avionics. A list of organizations represented on this committee can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. © The British Standards Institution 2013. Published by BSI Standards Limited 2013 ISBN 978 0 580 82732 7 ICS 03.100.50; 31.020; 49.060 Compliance with a British Standard cannot confer immunity from legal obligations. This Published Document was published under the authority of the Standards Policy and Strategy Committee on 31 October 2013. Amendments/corrigenda issued since publication Date Text affected PD IEC/TS 62647-22:2013 IEC/TS 62647-22 ® Edition 1.0 2013-09 TECHNICAL SPECIFICATION Process management for avionics – Aerospace and defence electronic systems containing lead-free solder – Part 22: Technical guidelines INTERNATIONAL ELECTROTECHNICAL COMMISSION PRICE CODE XB ICS 03.100.50; 31.020; 49.060 ISBN 978-2-8322-1112-0 Warning! Make sure that you obtained this publication from an authorized distributor. ® Registered trademark of the International Electrotechnical
    [Show full text]
  • Lead-Free Electronics Reliability - an Update
    Lead-free Electronics Reliability - An Update Andrew D. Kostic, Ph. D. The Aerospace Corporation GEOINT DEVELOPMENT OFFICE August 2011 © The Aerospace Corporation 2011 Lead (Pb) – Some Background • Lead (Pb) has been used by humans since at least 6500 BC – Pb solder use dates back to 3800 BC when it was used to produce ornaments and jewelry • Harmful effects of excess Pb on the human body are well documented – Pb gets into the body only through inhalation or ingestion – Acts as a neurotoxin, inhibits hemoglobin production, effects brain development – Children are more susceptible than adults • Dramatic reduction in blood Pb levels since 1975 due mainly use of Pb-free gasoline – 78% reduction documented in 1994 by EPA – Elimination of Pb from paints gave additional benefit 2 Lead Consumption • World wide consumption of refined Pb decreased slightly to 8.63 metric tons in 2009 from 8.65 metric tons in 2008 – The first annual decline in global Pb consumption since 2001 • The leading refined-Pb-consuming countries in 2009 were: – China 45% – United States 16% – Germany 4% – Republic of Korea 3%. • Consumption of refined Pb in the U.S. decreased by about 11% in 2009 Application 2009 U.S. Consumption Metal Products 5.8% Electronic Solder 0.5% Storage Batteries 88.3% 1) International Lead and Zinc Study Group (2010c, p. 8–9) (ILZSG), 2) Data from USGS statistics 3 Pb in the Electronics Industry • Electronic component terminations have been electroplated and soldered to circuit boards with tin/lead (Sn/Pb) solder for many decades • The entire
    [Show full text]
  • Surface Technology White Papers 98 (6), 18-27 (September 2011)
    Surface Technology White Papers 98 (6), 18-27 (September 2011) Investigation of Tin Whisker Formation by Grazyna Koziol,*1 Aneta Arazna,1 Wojciech Stęplewski,1 Kamil Janeczek1 and Jerzy Bielinski2 1Tele- and Radio Research Institute, Ratuszowa, Poland, 2Warsaw University of Technology, Faculty Chemistry, Noakowskiego, Poland ABSTRACT Tin and its alloys have been widely used in electronics as surface finish materials in printed circuit boards and connectors. SnAgCu and SnCu alloys have been applied in lead-free reflow and wave soldering processes. It is known that tin whiskers can form on pure tin or tin-alloy finished surfaces and grow up to several millimeters in length with a diameter of a few micrometers. Since the smallest distance between components can be less than a few hundred micrometers, whiskers can create reliability problems. Tin whisker formation was investigated on different types of immersion tin and SnAgCu alloy (HASL) surface finishes for printed circuit boards, and electroplated tin and tin-bismuth for connectors after lead-free soldering processes. After longtime storage and accelerated tests, it was found that whisker formation is a long term process and the important factors contributing to whisker formation on electroplated tin were high humidity, enough to produce condensation at elevated temperatures and variable environmental hazards. For immersion tin coatings thinner than 1.0 µm, the tests performed produced some small areas in which tin was completely transformed into SnCu intermetallic compounds rather than whisker growth. Keywords: Tin whiskers, electroplated tin, electronic components Introduction Immersion tin and lead-free hot air solder leveling (HASL) coatings based on SnCu or SnAgCu alloys are widely used as surface finish materials for printed circuit boards (PCB).
    [Show full text]
  • Tin and Tin Alloy Coatings Over Ferrous Basis Metals
    NOTICE TABLE OF CONTENTS The procedures included in this book are advisoiy onlylrrnd their use by anyone is entirely voluntary. Reliance on an of INTRODUCTION ................................... 1-3 the contents of this book for any purpose by anyone a the is i; DESIGN FOR ELECTROPLATING ...................... 4-10 sole risk of that person and neither the MFSA nor its members are responsible for any loss. claim or damage arising therefrom. DESCRIPTION OF THE TIN AND TIN ALLOY FINISHES ..... 10-12 A user of this book should consult a technically competent SELECTING THE COATING .................. .(See Center Fold1 person to determine what procedure or material. whether PROPERTIESOF THE DEPOSIT ....................... 12 included in this book or not. is appropriate for that user's Corrosion Resistance ............................ 12-14 application. By way of example only. the user will need to Solderability .................................. 14-16 determine whether application problems or the environment Toxicity .................................... 16 to which the plated item will be exposed will require Electrical Properties .............................. 17 procedures different from those here set out. and will also Hydrogen Embrittlement .......................... 18 have to determine what plating material is most appropriate Covering Castings .............................. 18-19 for the user's application. In addition. the user is responsible ~ Formability .................................. 19 for work place safety. environmental protection. etc., and SPECIFYING THE COATING .......................... 19 neither MFSA nor its members represent that use of the Thickness ................................... 19 procedures or materials set out herein will be free from i Porosity .................................... 26 challenge. While the MFSA has made a determined effort to present state of the art plating technologv and also to present 1 Adhesion .................................... 26 the contents of this book accurately.
    [Show full text]
  • Dr. Jennie Hwang to Deliver Two Courses On
    News Release Dr. Jennie Hwang to deliver two courses on “Package/Board Integrity & Solder Joint Reliability” on October 7th and “Preventing Product Failure” on October 8th at IMAPS 2020 International Symposium on Microelectronics, Dr Jennie S. Hwang leverages decades of extensive real-world experiences and deep knowledge to deliver two Professional Development Courses – 1. “Package/Board Integrity & Solder Joint Reliability” and 2. “Preventing Product Failure.” Registration: https://imaps.org/symposium_pdcs.php#a7 https://imaps.org/symposium_pdcs.php#b8 Info: [email protected] With the goal to produce reliable products while achieving high yield production, the course on “Package/Board Integrity & Solder Joint Reliability” provides a holistic overview of product reliability and of critical 'players' of the package/board level integrity and solder joint reliability, including the roles of materials, processes and testing/service conditions, as well as the crucial principles behind the product reliability. Recent developments related to lead-free package and board assembly, lead-free solder materials, PCB laminates and surface finishes in relation to manufacturability and reliability will be outlined. The likely solder joint failure modes (interfacial, near-interfacial, bulk, inter-phase, intra-phase, voids-induced, surface-crack and others) will be illustrated. Solder joint reliability fundamentals including fatigue and creep damage mechanisms via ductile, brittle, ductile-brittle fracture will be outlined. To withstand harsh environments, the strengthening metallurgy to further increase fatigue resistance and creep resistance and the power of metallurgy and its ability to anticipate the relative performance will be illustrated by examining the comparative performance in relation to metallurgical phases and microstructures of solder joints.
    [Show full text]
  • Excerpt of Final Report 2012
    Assistance to the Commission on technological, socio-economic and cost-benefit assessment related to exemptions from the substance restrictions in electrical and electronic equipment (RoHS Directive) Final report Freiburg, 12 December 2012 Excerpt of Final Report 2012 Öko-Institut e.V. – Institute for Applied Ecology, Öko-Institut e.V. Germany (main contractor) Freiburg Head Office P.O. Box 17 71 Carl-Otto Gensch 79017 Freiburg, Germany Street Address Yifaat Baron Merzhauser Str. 173 Markus Blepp 79100 Freiburg Phone +49 (0) 761 – 4 52 95-0 Andreas Manhart Fax +49 (0) 761 – 4 52 95-288 Katja Moch Darmstadt Office Rheinstr. 95 64295 Darmstadt, Germany Phone +49 (0) 6151 – 81 91-0 Fraunhofer Institute for Reliability and Fax +49 (0) 6151 – 81 91-133 Microintegration – IZM (subcontractor) Berlin Office Otmar Deubzer Schicklerstr. 5-7 10179 Berlin, Germany Phone +49 (0) 30 – 40 50 85-0 Fax +49 (0) 30 – 40 50 85-388 RoHS 2 exemptions evaluation Final report 11 Exemption request no. 8 “Lead in Solder for Electrical Circuitry that is used at Temperatures below -20°C” COCIR (2011) requests an exemption for “Lead in Solder for Electrical Circuitry that is used at Temperatures below -20°C”. Abbreviations Ag silver Bi bismuth MEG magneto-encephalography MRI magnetic resonance imaging NMR nuclear magnetic resonance Pb lead Sn tin SQUID superconducting quantum interference device 11.2 Description of requested exemption COCIR (2011) explains that exemption 12 in RoHS Annex IV allows the use of “Lead and cadmium in metallic bonds to superconducting materials in Magnetic Resonance Imaging (MRI) and Superconducting Quantum Interference Device (SQUID) detectors”.
    [Show full text]