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1
Weller, Sean David Tomey. "Lead-free solder technology." Thesis, University of Birmingham, 2010. http://etheses.bham.ac.uk//id/eprint/5575/.
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Aerospace applications typically require electronic products with not only higher levels of reliability than the consumer electronics industry but also longer service lives within demanding working environments. The transition will inevitably mean changes to design and manufacturing procedures, which is likely to incur a significant cost to the business. For example, the best candidate Pb-free solder alloys have been shown to require higher soldering temperatures and have higher surface tensions. Moreover, a reduction in product safety and reliability is not acceptable to the industry. This present work is divided into three sections. Firstly, the effect of increased component soldering temperatures on the integrity of the epoxy laminate material used for manufacture of printed circuit boards (PCB) has been assessed. Secondly, the required changes in soldering process parameters have been investigated for a range of solders and PCB finishes, largely due to the different wetting characteristics brought about by the increased surface tension of the Pb-free solders. Thirdly, the reliability of SnAgCu solder is assessed in comparison to the currently utilised SnPbAg solder alloy. This has been achieved firstly by accelerated thermal cycling, as the dominant mode of failure in a solder joint is typically thermo-mechanical fatigue and as such is already well researched. In addition, the mechanical fatigue properties have been assessed using a novel accelerated vibration test method and then finally, the two individual accelerated environmental tests of thermal cycling and vibration have been combined in a novel way to assess whether the combination is especially dangerous for SnAgCu solder reliability. A secondary objective of the combined environment test was to see if the well established thermal cycling test method for demonstration of product reliability can be further accelerated while still producing solder joint failure representative of those in-service. The present work shows that SnAgCu solder has inferior thermo-mechanical and mechanical fatigue life to SnPbAg solder. A combined environment test has been developed which effectively combines the single environments of thermal and vibration. The combination of thermal cycling with superimposed vibration is especially dangerous for SnAgCu solder, where an 89% reduction in the characteristic life is observed when compared to the equivalent thermal cycling characteristic life. It is suspected that a large reduction in life will be observed in SnPbAg solder, but not as pronounced as SnAgCu due to SnPbAg solders ability to better withstand plastic deformation that is induced by thermal cycling.
2
Iyer, Ganesh R. "Role of intermetallics for both tin-lead and lead free solder structures and its solder pad combination." Diss., Online access via UMI:, 2005.
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3
Mitchell, Charles Clayton. "PBGA reliability of lead free solder balls assembled with tin lead solder paste for harsh environment electronics." Auburn, Ala., 2006. http://repo.lib.auburn.edu/2006%20Summer/Theses/MITCHELL_CHARLES_16.pdf.
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4
Reid, Pamela Patrice. "Variable Frequency Microwave Reflow of Lead-Free Solder Paste." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5011.
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As the world moves towards eliminating lead from consumer products, the microelectronics industry has put effort into developing lead-free solder paste. The major drawback of lead-free solder is the problems caused by its high reflow temperature. Variable frequency microwave (VFM) processing has been shown to allow some materials to be processed at lower temperatures. Issues addressed in this study include using VFM to reduce the solder reflow temperature, comparing the heating rate of different size solder particles, and comparing the reliability of VFM reflowed solder versus conventionally reflowed solder. Results comparing the effect of particle size on the heating rate of solder showed that the differences were negligible. This is due in part to the particle sizes overlapping. Many lead-free solder pastes reflow around 250℃. Results indicate that when using the VFM, lead-free solder paste will reflow at 220℃. The reliability of solder that was reflowed using the VFM at the reduced temperature was found to be comparable to solder reflowed in a conventional manner. Based on these findings, VFM processing can eliminate the major obstacles to making lead-free solder paste a more attractive option for use in the microelectronics industry.
5
Lewin, Susanne. "Mechanical Reliability of Aged Lead-Free Solders." Thesis, KTH, Materialvetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-98372.
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The usage of lead-free solder joints in electronic packaging is of greatest concern to the electronic industry due to the health and environmental hazards arising with the use of lead. As a consequence, lead is legally prohibited in the European Union and the industry is aiming to produce lead-free products. The reliability of solder joints is an important issue as the failure could destroy the whole function of a product. SnAgCu is a commonly used alloy for lead-free solders. Compared to solders containing lead, tin-rich solders react more rapidly with the copper substrate. The reaction results in formation of brittle intermetallic compounds and in poor mechanical reliability. The formation can be slowed down by the addition of nickel in the under bump metallization. In this project the objective was to evaluate the mechanical reliability of solder joints in high temperature applications. An alloy of nickel and phosphorus was plated on copper plates by electroless plating. The plates were joined together using SnAgCu solder. The samples were then thermally aged at 180°C for different durations (100, 200, 300, 400 and 500 hours). Tensile tests were performed on the samples. The result from the tensile test showed a decrease in mechanical strength with increasing aging duration. The fracture path shifted from being in the bulk solder to being at the interfaced.
6
Anson, Scott J. "Analysis of lead free tin-silver-copper and tin-lead solder wetting reactions." Diss., Online access via UMI:, 2007.
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7
Stinson-Bagby, Kelly Lucile. "Microstructural Evolution in Thermally Cycled Large-Area Lead and Lead-Free Solder Joints." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/34573.
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Currently, there are two major driving forces for considering alternative materials to lead-
based products, specifically interconnections, in electronics applications, including the
impending legislation or regulations which may tax, restrict, or eliminate the use of lead
and the trend toward advanced interconnection technology, which may challenge the
limits of present soldering technology. The reliability of solder joints is a concern
because fracture failures in solder joints accounts for 70% of failures in electronic
components. Lead-free solders are being investigated as replacements for lead solders
currently used in electronics. Thermo-mechanical properties describe the stresses
accumulated due to thermal fatigue as a result of CTE mismatch within the system. By
understanding the failure mechanisms related to lead-free solders, the application of lead-
free solders could be more strategically designed for specific applications.
The objective of this thesis is to observe microstructural change in large-area solder joints
caused by thermal cycling and relate these changes to reliability issues in large-area lead
and lead-free solder constructed semiconductor power devices. This study focused on the
microstructural changes within the solder alloy of a large-area solder joint under thermal
cycling conditions. Two major primary observations were made from this research, they
are: 1) due to a combination of testing conditions and material properties, the lead-free
solders, Sn/3.5Ag and Sn/Ag/0.7Cu, sustained the most severe damage as compared to
Sn/37Pb, and 2) due to elevated stresses at the solder/substrate interface in a simulated
power semiconductor device sample damage was found to be most severe.Master of Science
8
Marquez, de Tino Ursula. "Reduction of nitrogen consumption of lead-free reflow processes and prediction models for behaviors of lead-free assemblies." Diss., Online access via UMI:, 2009.
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Thesis (Ph. D.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Systems Science and Industrial Engineering, 2009.Includes bibliographical references.
9
Bhave, Aniket. "A leaded and lead-free solder paste evaluation screening procedure." Diss., Online access via UMI:, 2005. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:1425610.
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10
Woo, Belemy Hok Chung. "Solderability & microstructure of lead-free solder in leadframe packaging." access abstract and table of contents access full-text, 2005. http://libweb.cityu.edu.hk/cgi-bin/ezdb/dissert.pl?msc-ap-b21175214a.pdf.
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Thesis (M.Sc.)--City University of Hong Kong, 2005.At head of title: City University of Hong Kong, Department of Physics and Materials Science, Master of Science in materials engineering & nanotechnology dissertation. Title from title screen (viewed on Sept. 4, 2006) Includes bibliographical references.
11
Kirkpatrick, Timothy. "The kinetics of tin solidification in lead-free solder joints." Diss., Online access via UMI:, 2006.
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12
Dhakal, Ramji. "Failure mechanism of lead-free Sn-Ag-Cu solder BGA interconnects." Diss., Online access via UMI:, 2005.
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13
Qin, Yi. "Electrodeposition and characterisation of lead-free solder alloys for electronics interconnection." Thesis, Loughborough University, 2010. https://dspace.lboro.ac.uk/2134/7788.
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Conventional tin-lead solder alloys have been widely used in electronics interconnection owing to their properties such as low melting temperature, good ductility and excellent wettability on copper and other substrates. However, due to the worldwide legislation addressing the concern over the toxicity of lead, the usage of lead-containing solders has been phased out, thus stimulating substantial efforts on lead-free alternatives, amongst which eutectic Sn-Ag and Sn-Cu, and particularly Sn-Ag-Cu alloys, are promising candidates as recommended by international parties. To meet the increasing demands of advanced electronic products, high levels of integration of electronic devices are being developed and employed, which is leading to a reduction in package size, but with more and more input/output connections. Flip chip technology is therefore seen as a promising technique for chip interconnection compared with wire bonding, enabling higher density, better heat dissipation and a smaller footprint. This thesis is intended to investigate lead-free (eutectic Sn-Ag, Sn-Cu and Sn-Ag-Cu) wafer level solder bumping through electrodeposition for flip chip interconnection, as well as electroplating lead-free solderable finishes on electronic components. The existing knowledge gap in the electrochemical processes as well as the fundamental understanding of the resultant tin-based lead-free alloys electrodeposits are also addressed. For the electrodeposition of the Sn-Cu solder alloys, a methanesulphonate based electrolyte was established, from which near-eutectic Sn-Cu alloys were achieved over a relatively wide process window of current density. The effects of methanesulphonic acid, thiourea and OPPE (iso-octyl phenoxy polyethoxy ethanol) as additives were investigated respectively by cathodic potentiodynamic polarisation curves, which illustrated the resultant electrochemical changes to the electrolyte. Phase identification by X-ray diffraction showed the electrodeposits had a biphasic structure (β-Sn and Cu6Sn5). Microstructures of the Sn-Cu electrodeposits were comprehensively characterised, which revealed a compact and crystalline surface morphology under the effects of additives, with cross-sectional observations showing a uniform distribution of Cu6Sn5 particles predominantly along β-Sn grain boundaries. The electrodeposition of Sn-Ag solder alloys was explored in another pyrophosphate based system, which was further extended to the application for Sn-Ag-Cu solder alloys. Cathodic potentiodynamic polarisation demonstrated the deposition of noble metals, Ag or Ag-Cu, commenced before the deposition potential of tin was reached. The co-deposition of Sn-Ag or Sn-Ag-Cu alloy was achieved with the noble metals electrodepositing at their limiting current densities. The synergetic effects of polyethylene glycol (PEG) 600 and formaldehyde, dependent on reaching the cathodic potential required, helped to achieve a bright surface, which consisted of fine tin grains (~200 nm) and uniformly distributed Ag3Sn particles for Sn-Ag alloys and Ag3Sn and Cu6Sn5 for Sn-Ag-Cu alloys, as characterised by microstructural observations. Near-eutectic Sn-Ag and Sn-Ag-Cu alloys were realised as confirmed by compositional analysis and thermal measurements. Near-eutectic lead-free solder bumps of 25 μm in diameter and 50 μm in pitch, consisting of Sn-Ag, Sn-Cu or Sn-Ag-Cu solder alloys depending on the process and electrolyte employed, were demonstrated on wafers through the electrolytic systems developed. Lead-free solder bumps were further characterised by material analytical techniques to justify the feasibility of the processes developed for lead-free wafer level solder bumping.
14
Anastasio, Onofrio A. "An approach for impression creep of lead-free microelectronic solders." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02Jun%5FAnastasio.pdf.
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15
Mukherjee, Shantanu. "Lead-free wave soldering of "thick" PCB using Sn 3.8% Ag 0.07% Cu and no-clean voc-free flux." Diss., Online access via UMI:, 2007.
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16
Huang, Zhiheng. "Materials issues in the transition to lead-free solder alloys and joint miniaturization." Thesis, Loughborough University, 2005. https://dspace.lboro.ac.uk/2134/25232.
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Within the context of the imminent implementation of the Pb-free soldering in Europe in 2006, this thesis addresses the gap in understanding that has emerged in the fundamental materials issues between well-understood and mature lead-containing solders and a plethora of new, Pb-free solders for which there are neither long term reliability data nor understanding of the materials behaviour and how these might be influenced by manufacture and in-service conditions. In addition, this thesis also addresses the question as to whether the solder joint size and geometry could become a reliability issue and therefore affect the implementation of the Pb-free solders in ultrafine micro joints. Thermodynamic calculations using MTDATA (developed by the National Physical Laboratory, NPL, UK) together with a thermodynamic database for solders under either equilibrium or Scheil conditions, have shown their usefulness in Pb-free solder design and processing, generating a wealth of information in respect of the temperature dependence of phase formation and composition. The predictions from MTDATA on a number of selected systems is generally in good agreement with the results from experimental work, and has assisted in the understanding of the microstructure and mechanical properties of the Pb-free solders and the implications of their interactions with a tin-lead solder. However, further critical assessment and the addition of new elements into the solder database, such as Ni and P, are required to make MTDA TA a more effective computational tool to assist the optimization of processing parameters and cost-effective production in using Pb-free solders. Molten solder can interact with the under bump metallizations (UBM) and/or board level metallizations on either side of the solder bump to form intermetallic compounds (IMCs) during solder reflow. In the modelling of the kinetics of the dissolution process of UBM into the liquid solder, the commonly used NernstBrunner (N-B) equation is found to have poor validity for these calculations for micro joints at 100 μm in diameter or less. Three bumping techniques, i.e. solder dipping (SD), solder paste stencil printing followed by reflow (SPR) and electroplating of solders and subsequent reflow (EPR), are used to investigate the interfacial interactions of molten Sn/Sn-rich solders, i.e. pure Sn, Sn-3.5Ag, and Sn-3.8AgO.7Cu, on electroless nickel immersion gold (ENIG) and copper pads at 240°C. The resultant bulk and interfacial microstructures from a variety of pad sizes, ranging from 1 mm down to 25 μm, suggest that in general the small bumps contain smaller β-Sn dendrites and Ag₃Sn IMC particles, nevertheless the interfacial IMC is thicker in the smalI bumps than in the large bumps. In addition, one and two-dimensional combined thermodynamic and kinetic models have been developed to assist the understanding of the kinetics of interdiffusion and the formation of interfacial intermetallic compounds during reflow. Both the experimental results and theoretical predictions suggest that the solder bump size and geometry can influence the as-soldered microstructure, and therefore this factor should be taken into consideration for the design of future reliable ultrafine Ph-free solder joints.
17
Baynham, Grant Andrew. "Flip chip processing of lead-free solders and halogen-free high density microvia substrates." Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/19313.
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18
Horton, W. Scott. "Thermomechanical cycling investigation of CU particulate and NITI reinforced lead-free solder." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2006. http://library.nps.navy.mil/uhtbin/hyperion/06Sep%5FHorton.pdf.
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Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, September 2006.Thesis Advisor(s): Indranath Dutta. "September 2006." Includes bibliographical references (p. 55-58). Also available in print.
19
Jud, Pascal P. [Verfasser]. "Deformation and Degradation of Sn3.8Ag0.7Cu Lead-free Solder Alloy / Pascal P Jud." Aachen : Shaker, 2006. http://d-nb.info/1170534007/34.
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20
Ghosh, Santaneel. "A Non-Contact Measurement Technique At The Micro Scale." Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1421%5F1%5Fm.pdf&type=application/pdf.
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21
Nousiainen, O. (Olli). "Characterization of second-level lead-free BGA interconnections in thermomechanically loaded LTCC/PWB assemblies." Doctoral thesis, Oulun yliopisto, 2010. http://urn.fi/urn:isbn:9789514263538.
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Abstract
Low-temperature co-fired ceramic (LTCC) based system-in-package (SiP) is an emerging multilayer module technology for wireless communication applications, mainly due to its excellent high-frequency material properties. LTCC-SiP modules are typically soldered onto an organic motherboard, but the lifetime of the 2nd-level solder joints is often poor due to the high stress level of the joints in test/field conditions. Moreover, using lead-free solders in the interconnections of LTCC modules raised new questions about the feasibility and reliability of the solder joints in LTCC applications. Therefore, the characteristic features of the 2nd-level solder joint configuration were determined in this thesis work.
It was proved that collapsible Sn4Ag0.5Cu spheres are not a feasible option in LTCC/PWB assemblies with a large global thermal mismatch; a non-collapsible ball grid array (BGA) joint with a plastic core solder balls (PCSBs) was required to attain an adequate lifetime for such assemblies. To enhance the thermal fatigue endurance of the non-collapsible lead-free joints, a novel BGA joint consisting of Sn7In4.1Ag0.5Cu solder and PCSBs was developed. Moreover, this work proved that there is a relationship between the primary failure mechanisms of various Sn-based lead-free solders and thermomechanically induced stress level in the present non-collapsible BGA joint configuration.
The effect of the plating material of the solder lands on the failure mechanism of the BGA joints in the LTCC/PWB assemblies was studied. The results showed that the adverse phenomena related to the sintered Ag-based metallization materials can be avoided using electroless nickel with immersion gold (ENIG) as a deposit material. On the other hand, this study also demonstrated that the inadequate adhesion strength of the commercial base metallization in the ENIG-plated modules resulted in the disadvantageous failure mechanism of the test assemblies. Therefore, the criteria for material selection and the design aspects of reliable 2nd-level interconnections are discussed thoroughly in this thesis.
22
Zha, Xu. "Numerical analysis of lead-free solder joints : effects of thermal cycling and electromigration." Thesis, Loughborough University, 2016. https://dspace.lboro.ac.uk/2134/23446.
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To meet the requirements of miniaturization and multifunction in microelectronics, understanding of their reliability and performance has become an important research subject in order to characterise electronics served under various loadings. Along with the demands of the increasing miniaturization of electronic devices, various properties and the relevant thermo-mechanical-electrical response of the lead-free solder joints to thermal cycling and electro-migration become the critical factors, which affect the service life of microelectronics in different applications. However, due to the size and structure of solder interconnects in microelectronics, traditional methods based on experiments are not applicable in the evaluation of their reliability under complex joint loadings. This thesis presents an investigation, which is based on finite-element method, into the performance of lead-free solder interconnects under thermal fatigue and electro-migration, specifically in the areas as follows: (1) the investigation of thermal-mechanical performance and fatigue-life prediction of flip-chip package under different sizes to achieve a further understanding of IMC layer and size effects of a flip chip package under thermal cycling; (2) the establishment of a numerical method, simulating void-formation/crack-propagation based on the results of finite-element analysis, to allow the prediction of crack evolution and failure time for electro-migration reliability of solder bumps; (3) the establishment of a flow-based algorithm for combination effects of thermal-mechanical and electro-migration that was subsequent implemented in to an FE model to evaluate the reliability assessment of service lives associated with a flip chip package.
23
Berglund, Ove. "Implementation of Lead-Free Soldering in Highly Reliable Applications." Thesis, Linköping University, Department of Science and Technology, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-8779.
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The directive of the European parliament and of the council on the Restriction of the use of certain Hazardous Substances (RoHS) in Electrical and Electronic Equipment (EEE) took effect in the European Union on July 1, 2006. Japan, California, China and Korea are all closed markets for exporters of components containing lead from July 1, 2007. Taiwan and Australia are working with similar directives. The RoHS directive is the reason why this thesis about the implementation of lead-free soldering in highly reliable applications is necessary.
The European Lead Free soldering NETwork (ELFNET) status survey from 2005 shows that the majority of the companies are well informed, but 20% are still not active in lead-free soldering. The Swedish industry is for the most part prepared and 95% of the components are lead-free. The transition to lead-free soldering will have a major affect on logistics and administration, because the RoHS directive is 90% about administration and logistics problems. Only 10% is technical problems.
The higher melting point in lead-free soldering affects every stage of the lead-free manufacturing, from assembly to testing and repair.
The major concern for highly reliable applications are that there are not enough data to understand to what grade lead-free solders will perform differently from lead based solders. Five different types of reliability testing were studied in this thesis; vibration, mechanical shock, thermal shock, thermal cycling and combined environments. Whiskers, voids, brittle fractures and mixed assembly problems were also studied. Individual tests alone should not be used to make definite decisions on lead-free soldering reliability. The lower reliability for lead-free solders in some tests does not necessarily mean that lead-free solders not can be used in highly reliable applications like defence electronics.
The most important conclusions from this thesis are:
• Update or change the logistic system and mark/label according to available standards.
• Secure a good board layout.
• Secure a good process control.
• Alternative surface board should be used. Tin-silver-copper (SAC) is the most reliable solder and Electroless Nickel/Immersion Gold (ENIG) is the most reliable surface finish.
• Remember that the higher temperature affects every stage of the manufacturing.
• No increased problems with whiskers or risk of high voiding levels.
• Mixed assembly is a risk. Compatibility and contamination risks must be taken seriously.
• Which environment will the applications be in? If it is not a highly vibrating and thermal cycling environment, lead-free soldering should be safe to use.
Europaparlamentets och rådets direktiv om begränsning av användningen av vissa farliga ämnen i elektriska och elektroniska produkter började gälla i Europeiska unionen 1 juli, 2006. Japan, Kalifornien, Kina och Korea är alla stängda marknader för exportörer av komponenter som innehåller bly från och med 1 juli, 2007. Taiwan och Australien arbetar med liknande direktiv. RoHS-direktivet är anledningen till varför detta examensarbete om implementeringen av blyfri lödning i högtillförlitliga applikationer är nödvändigt.
En undersökning från 2005 av ELFNET visar att majoriteten av företagen är väl informerade, men 20% är fortfarande i aktiva med blyfri lödning. Den svenska industrin är till största delen väl förberedd och 95% av komponenterna är blyfria. Övergången till blyfri lödning kommer att ha stor effekt på logistik och administration, därför att 90% är administrations- och logistikproblem i RoHS-direktivet. Bara 10% är tekniska problem.
Den högre smälttemperaturen i blyfri lödning påverkar varje steg av den blyfria tillverkningen, från montering till testning och reparation.
Den stora oron för högtillförlitliga applikationer är att det inte finns tillräckligt med data för att förstå i vilken grad som blyfria lod kommer att bete sig annorlunda jämfört med blybaserade lod. Fem olika typer av tillförlitlighetstester har undersökts i detta examensarbete; vibration, mekanisk chock, termisk chock, termisk cykling och kombinerade tester. Whiskers, voids, sprödbrott och blandad montering studerades också. Individuella tester ska inte användas för att ta några definitiva beslut om blyfri lödnings tillförlitlighet. Den lägre tillförlitligheten för blyfria lod i en del tester behöver nödvändigtvis inte betyda att blyfria lod inte kan användas i högtillförlitliga applikationer som försvarselektronik.
De viktigaste slutsatserna från detta examensarbete är:
• Uppdatera eller byt logistiskt system och märk enligt tillgängliga standarder.
• Säkerställ en bra kretskortsdesign.
• Säkerställ en bra processkontroll.
• Alternativa mönsterkort bör användas. SAC är det tillförlitligaste lodet och ENIG är den tillförlitligaste ytbehandlingen.
• Kom ihåg att den ökade temperaturen påverkar varje steg i tillverkningen.
• Inga ökade problem med whiskers eller stort antal voids.
• Blandmontage är riskfyllt. Kompatibilitet och risker med kontaminering måste tas på allvar.
• Vilken miljö kommer applikationen att befinna sig i? Är det inte en starkt vibrerande eller temperaturcyklisk miljö bör blyfri lödning vara säkert att använda.
24
Farris, Andrew Liddicoat Albert A. "Drop impact reliability testing lead-free chip scale packages : a thesis /." [San Luis Obispo, Calif. : California Polytechnic State University], 2008. http://digitalcommons.calpoly.edu/theses/21/.
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Thesis (M.S.)--California Polytechnic State University, 2008.Major professor: Albert Liddicoat, Ph.D. "Presented to the faculty of California Polytechnic State University, San Luis Obispo." "In partial fulfillment of the requirements for the degree [of] Master of Science in Electrical Engineering." "June 2008." Includes bibliographical references (leaves 70-73). Also available online. Also available on microfiche (2 sheets).
25
Nalagatla, Dinesh Reddy. "INFLUENCE OF SURFACE ROUGHNESS OF COPPER SUBSTRATE ON WETTING BEHAVIOR OF MOLTEN SOLDER ALLOYS." UKnowledge, 2007. http://uknowledge.uky.edu/gradschool_theses/488.
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The objective of this study is to understand the effect of surface roughness of the Cu substrate on the wetting of molten solder alloys. Eutectic Sn-Pb, pure Sn and eutectic Sn-Cu solder alloys and Cu substrates with different surface finish viz., highly polished surface, polished surface and unpolished surface were used in this work. Highly polished surface was prepared in Metallography lab, University of Kentucky while other two substrates were obtained from a vendor. Surface roughness properties of each substrate were measured using an optical profilometer. Highly polished surface was found to be of least surface roughness, while unpolished surface was the roughest. Hot-stage microscopy experiments were conducted to promote the wetting behavior of each solder on different Cu substrates. Still digital images extracted from the movies of spreading recorded during hot-stage experiments were analyzed and data was used to generate the plots of relative area of spread of solder versus time. The study of plots showed that surface roughness of the Cu substrate had major influence on spreading characteristics of eutectic Sn-Pb solder alloy. Solder showed better spreading on the Cu substrate with least surface roughness than the substrates with more roughness. No significant influence of surface roughness was observed on the wetting behavior of lead free solders (pure Sn and eutectic Sn-Cu).
26
Vishwanathan, Krishnan. "Process development and microstructural analysis of capacitor filter assemblies using lead free solder preforms." Diss., Online access via UMI:, 2007.
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Thesis (M.S.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Systems Science and Industrial Engineering, 2007.Includes bibliographical references.
27
Cooper, Shellene. "Creep behaviour of the ternary lead-free solder alloy, Sn-3.8wt.%Ag-0.7wt.%Cu." Thesis, Open University, 2002. http://oro.open.ac.uk/54417/.
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Electronic equipment is facing the challenge of both miniaturisation and the need to replace lead in interconnections. In service, interconnections generally fail by thermomechanical fatigue, and this behaviour is strongly affected by the creep process. This thesis examines the creep behaviour of a popular lead-free replacement alloy, Sn-3.8wt.%Ag-0.7wt%Cu (Sn-Ag-Cu), in joint and bulk form. Experimental work involved the determination of the creep properties of this alloy at various temperatures, over a range of stresses. Over the regions tested, the creep behaviour is best described by the Norton power law constitutive equation. The stress exponent for bulk Sn-Ag-Cu ranged between 10 and 18 (at 125 to -lOoC respectively) and indicates that a dispersion-strengthened mechanism is dominant in the creep process. The activation energy for creep in the bulk Sn-Ag-Cu is approximately 120kJ/moi and falls in the region similar to that observed for the self-diffusion of tin. In joint form the stress exponent is greater than 10 at high stresses but a change in mechanism is indicated at lower stress where the creep exponent falls to 3. The activation energy for creep in Sn-Ag-Cu when used in joint form is approximately 70kJ/moi and falls in the region similar to that observed for the short-circuit diffusion of tin. Results obtained from the ternary alloy were directly compared to those from Sn- 37wt.%Pb (Sn-Pb) and other prospective lead-free alloys in bulk form. The creep resistance of the ternary lead-free alloy at 75°C is superior to the conventional Sn-Pb alloy and the possible replacement alloys (tin-copper and tin-silver). This superiority is retained when tested at similar homologous temperatures. However, the Sn-3.8Ag- O.7Cu alloy is less ductile but generally possesses strains to failure above 10 percent in comparison to the 25 to 50 percent ductility of Sn-Pb.
28
Chung, Tzu-hao, and 鐘子豪. "Lead-Free Solder Ball Interface Reaction Study." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/22g8c6.
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Lin, Chien-Hung, and 林建宏. "Shearing Behavior of Lead Free Solder Bumps." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/w2c99p.
Full textAbstract:
碩士國立中山大學
機械與機電工程學系研究所
95
The trend of electrical products is light, thin and minimized with the fast operation and multi functionality, which also drives assembly technology towards the same goal. In advanced assembly technology, flip-chip is the one that can achieve the purposes. The pitch and size of a bump, which is in charge of current transmit, are also getting small. The prohibition of using lead content material also stimulates the development of lead-free material in the related industries. The paper is focused on adopting lead free solder paste such as Sn/Ag1.0/Cu0.5 and Sn/Ag4.0/Cu0.5, together with Al/NiV/Cu UBM made by bumping technology. The empirical analysis is based the shear strength of three different bump heights. The result shows the higher the content of Ag, the higher of the initial shear strength. Moreover, the experiment also investigated two solder bump IMC conditions and shear strength by using multi-reflow. The result shows that the IMC of Sn/Ag4.0/Cu0.5 solder paste increases after times of multi-reflow, but the shear strength was sharply decreased. The reliability test was also performed, such as temperature cycling test, temperature and humidity test, highly accelerated temperature and humidity stress test, high temperature storage life test. It’s found the Sn/Ag1.0/Cu0.5 solder bump could maintain the original ductility; while the Sn/Ag4.0/Cu0.5 solder bump was decreasing the ductility due to the generation of IMC. Keyword：Shear Strength, Flip-chip, Bump, IMC
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"Properties of Cerium Containing Lead Free Solder." Doctoral diss., 2012. http://hdl.handle.net/2286/R.I.15802.
Full textAbstract:
abstract: With increasing concerns of the intrinsic toxicity of lead (Pb) in electronics, a series of tin (Sn) based alloys involving silver (Ag) and copper (Cu) have been proposed as replacements for Pb-Sn solder and widely accepted by industry. However, they have a higher melting point and often exhibit poorer damage tolerance than Pb-Sn alloys. Recently, a new class of alloys with trace amount of rare-earth (RE) elements has been discovered and investigated. In previous work from Prof. Chawla's group, it has been shown that cerium (Ce)-based Pb-free solder are less prone to oxidation and Sn whiskering, and exhibit desirable attributes of microstructural refinement and enhanced ductility relative to lanthanum (La)-based Sn-3.9Ag-0.7Cu (SAC) alloy. Although the formation of RESn3 was believed to be directly responsible for the enhanced ductility in RE-containing SAC solder by allowing microscopic voids to nucleate throughout the solder volume, this cavitation-based mechanism needs to be validated experimentally and numerically. Additionally, since the previous study has exhibited the realistic feasibility of Ce-based SAC lead-free solder alloy as a replacement to conventional SAC alloys, in this study, the proposed objective focuses on the in in-depth understanding of mechanism of enhanced ductility in Ce-based SAC alloy and possible issues associated with integration of this new class of solder into electronic industry, including: (a) study of long-term thermal and mechanical stability on industrial metallization, (b) examine the role of solder volume and wetting behavior of the new solder, relative to Sn-3.9Ag-0.7Cu alloys, (c) conduct experiments of new solder alloys in the form of mechanical shock and electromigration. The research of this new class alloys will be conducted in industrially relevant conditions, and the results would serve as the first step toward integration of these new, next generation solders into the industry.Dissertation/Thesis
Ph.D. Materials Science and Engineering 2012
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Lee, Yung-Tai, and 李泳泰. "Comparison of Lead Solder and Lead-Free Solder on the Application of Surface Mounting Technology." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/13954797776851341762.
Full textAbstract:
碩士中原大學
化學研究所
93
The traditional solders of 63wt%Sn-37wt%Pb which contains a high level of Pb, were widely applied on Surface Mounting Technology due to many excellent characteristics. However, many reports has been demonstrated that many electronic products contained Lead solders may causes an environmental pollution problems, thus the Lead-Free solders were rapidly developed in recent years. In order to compare the properties between commercial Lead-Free solders and traditional solders on the application of Surface Mounting Technology, several factors including solderability, wettability, spreadability, cold, hot shockability and thermal fatigue properties were examined. In the study, the experiments and measurement were completed based on a Ball Grid Array (BGA) planted solder balls processes. The results of solderability indicated that the 63wt%Sn-37wt%Pb solder balls were still perfect, but the Lead-Free solder balls (Sn-3.0wt%Ag-0.5wt%Cu) were drifted, and even had short phenomenons after the solderability test. The wettability and spreadability tests shown that the 63wt%Sn-37wt%Pb solder had a shorter average wetting time and a wider average spreading ratio than other Lead-Free solders 3~5Sec, thus the traditional solder has a better wettability and spreadability. SEM observation indicated that both 63wt%Sn-37wt%Pb solder and Lead-Free solders had no a morphological change after a cold, hot shockability tests. Integrated Circuit (IC) pins solder joints still were completed for Lead-Free solders after 10~30 times thermal fatigue test, however the IC pins solder joints were almost broken only 10 times thermal fatigue test for the traditional solder, 63wt%Sn-37wt%Pb.
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Kaila, Rishi. "Investigation of Mixed Solder Assemblies & Novel Lead-free Solder Alloys." Thesis, 2011. http://hdl.handle.net/1807/30652.
Full textAbstract:
Due to the introduction of Restriction of Hazardous Substances (RoHS) directive Pb containing solders have been banned from the electronics industry and a reliable replacement for the Sn-Pb solder is being sought for by industry around the globe. Medical and Defense industries are currently exempt from the directive and use Sn-Pb solder in their manufacturing process. The switch to lead-free has led component manufacturers to use different lead-free solders, thus causing mixed solder joints of lead-free components with Sn-Pb paste. In this study, mixed assembly microstructures and mechanical properties were examined. Furthermore, six novel lead-free solders were prepared using SAC105 solder doped with elements: Ti, Ni, Mn, La, Ce and Y. The solidification microstructures, fracture behavior and wetting properties of these solders were evaluated to find a suitable replacement for SAC105 solder.
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Hsu, Ying-Chao, and 許穎超. "Study of Electromigration in Lead-Free SnAg3.8Cu0.7 Solder." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/74106852762475809560.
Full textAbstract:
博士國立交通大學
材料科學與工程系所
94
Electromigration-induced failure of SnAg3.8Cu0.7 flip-chip solder joints was investyigated with Ti/Cr-Cu/Cu under-bump metallization (UBM) on the chip side and Cu/Ni(P)/Au pad on the BT board side. Electromigration damage was examined under the current density of 2 �e 104 A/cm2 at 100 ℃ and 150℃. The failure was found to be at the cathode/chip side and voids were observed at intermetallic compound/solder interface at the cathode chip side. Copper atoms were found to move in the direction of electron flow to form intermetallic compounds at the interface of the solder and the pad metallization on the substrate side due to current stressing. In addition, eutectic SnAg3.8Cu0.7 solder stripes was investigated in the vicinity of the device operation temperature of 100 �aC by using the edge displacement technique. Measurements were made for relevant parameters for electromigration of the solder, such as drift velocity, threshold current density, activation energy, as well as the product of diffusivity and effective charge number (DZ*). The threshold current densities were estimated to be 4.3 �e 104 A/cm2 at 80 �aC, 3.2 �e 104 A/cm2 at 100 �aC, and 1.4 �e 104 A/cm2 at 120 �aC. These values represent the maximum current densities that the SnAg3.8Cu0.7 solder can carry without electromigration damage at the three stressing temperatures. The electromigration activation energy was determined to be 0.45eV in the temperature range of 80℃ to 120℃. The measured products of diffusivity and the effective charge number, DZ*, were -1.8´10-10 cm2/sec at 80℃, -5.0´10-10 cm2/sec at 100℃, and -7.2´10-10 cm2/sec at 120℃. In the pre-annealing specimens, grain boundary and lattice diffusion have a different temperature dependence range from 80℃ to 140℃. The threshold current densities were measured to be 4.6 �e 104 A/cm2 at 80 �aC, 3.9 �e 104 A/cm2 at 100 �aC, and 2.2 �e 104 A/cm2 at 120 �aC. The measured activation energy was 0.8eV for the temperature ranges from 100 to 140℃.
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"Applied Meta-Analysis of Lead-Free Solder Reliability." Master's thesis, 2014. http://hdl.handle.net/2286/R.I.26878.
Full textAbstract:
abstract: This thesis presents a meta-analysis of lead-free solder reliability. The qualitative analyses of the failure modes of lead- free solder under different stress tests including drop test, bend test, thermal test and vibration test are discussed. The main cause of failure of lead- free solder is fatigue crack, and the speed of propagation of the initial crack could differ from different test conditions and different solder materials. A quantitative analysis about the fatigue behavior of SAC lead-free solder under thermal preconditioning process is conducted. This thesis presents a method of making prediction of failure life of solder alloy by building a Weibull regression model. The failure life of solder on circuit board is assumed Weibull distributed. Different materials and test conditions could affect the distribution by changing the shape and scale parameters of Weibull distribution. The method is to model the regression of parameters with different test conditions as predictors based on Bayesian inference concepts. In the process of building regression models, prior distributions are generated according to the previous studies, and Markov Chain Monte Carlo (MCMC) is used under WinBUGS environment.Dissertation/Thesis
Masters Thesis Industrial Engineering 2014
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PING, LIU YI, and 劉毅平. "Characterization of Clean-less Lead-free Solder Pastes." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/28992536131779988848.
Full textAbstract:
碩士華梵大學
機電工程研究所
96
Abstract Since the Rosin activated traditional solder Paste {Rosin Activated (RA)} Sn63/Pb37 alloy's composition is 63wt%Sn-37wt%Pb, and since the lead components will generate environmental pollution and hazards, thus, the research and development of Rosin mild activated solder Paste {Rosin Mild Activated (RMA)} are the focus of current efforts by all countries. This research is to study: the surface adhesion technology applications of currently available commercial solder powder North Sn62.8/Pb36.8/Ag0.4 alloys, they are based on Sn63/Pb37, Sn62:Pb36: Ag0.4 composition; the shapes of the solders are ball type or eclipse type; and the diameters of solder powders are 20-45, 25-45 or 20-38µm. And it will also carry out tests on the lead free alloys. The tests include cooper plate corrosion, wetting, dispersion, chromic acid silver test, cooper mirror test, surface insulation resistance (S.I.R) test, electron migration test, temperature-viscosity test, adhesion test, collapse property test, solder ball test, and adhesion index test etc. analytical experiments. Differences in solder surface type are observed under a Scanning Electron Microscope. (SPI) Experimental results show ball mount using BGA. (Ball Grid Array) In terms of Solder Ball Test: the convergent effects of Sn62.8/Pb36.8/Ag0.4 solder ball are complete. In terms of wettability, the curve of Wetting Balance shows that the average wetting time of Sn62.8/Pb36.8/Ag0.4 solder is between 3 ~ 5sec. In terms of diffusivity: the average rate of diffusion for Sn62.8/Pb36.8/Ag0.4 solder is 76 ~ 80%。
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Ke, Kun –. Sheng, and 柯坤昇. "Study on Reliability of Lead-Free IC Solder." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/45237853002255336050.
Full textAbstract:
碩士國立高雄應用科技大學
電子工程系
98
The traditional solders of 63wt%Sn-37wt%Pb(63Sn37Pb) which contains a high level of Pb, were widely applied on Surface Mounting Technology . Howerver, many reports has been demonstrated that many electronic products which contained Lead solders may causes the problem of the environmental pollution , thus the Lead-Free solders were rapidly developed in recent years. In this paper , the different reliability of the 96.5wt%Sn-3.0wt%Ag -0.5wt%Cu four lead-free solder and 63wt%Sn-37wt%Pb solder were investigated . The surfaces of the various solders were measured by Scanning Electron Microscopy (SEM). The experimental results show that the capacity creep resistance of two lead-free solder Sn-Ag-Cu-Bi and Sn-Ag-Sb were significantly better than 60Sn40Pb solder, the creep rate is much smaller than 60Sn40Pb solder, and the creep variable life of fracture is greatly enhanced, particularly, the expectancy of Sn-Ag-Sb solder creep longest life. At the same time, The prediction of fatigue life for the solder joints of flip-chip plastic ball grid array packages under thermal shock tests was investigated in the present study. Finite element method was employed to simulate the deformation and stress/strain behavior of the packages. The stress/strain behavior of the flip chip-type plastic ball grid array package under the thermal shock test was studied by the finite element analysis and evaluate the fatigue life of the solder ball by the prediction formula of fatigue life. The simulation of Double Power Law Model, Hyperbolic Sine Law Model or Norton's Model was adopted . Through analysis, lead-free solder greatly improved the reliability of the solder joints, thermal fatigue life is more than four times the SnPb solder joints in the same circumstances.
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Huang, Chia-Wei, and 黃家緯. "Evaluation of Lead-free Sn-Zn Based Solders (Sn-Zn-Al-Ag Solder)." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/13319573590244426749.
Full textAbstract:
博士國立成功大學
材料科學及工程學系碩博士班
93
Abstract The development of lead-free solders has become an important issue in the electronics packaging industry because of environmental and health concerns. Recently, Sn-Zn based solders have been considered to be a potential candidate for lead-free solder because its melting temperature is relatively close to that of eutectic Sn-Pb solder. Sn-Zn solders also have lower cost than other lead-free solders. However, Sn-Zn solders exhibit unsatisfactory oxidation resistance and poor wettability on commonly used substrates. The purpose of this research is to investigate the incorporation of Al and Ag in Sn-Zn solder in order to enhance its wettability and oxidation resistance. The microstructure, mechanical property, wettability, oxidation behavior, interfacial reaction and reliability of the Sn-8.55Zn-0.45Al-(0~3wt%)Ag solders were investigated in this study. The microstructure of Sn-Zn based solders shows that the AgZn3 and Ag5Zn8 compounds are formed at the addition of (0.5wt%~3wt%)Ag to Sn-8.55Zn-0.45Al solders. The formation of Ag-Zn compounds (AgZn3 and Ag5Zn8) results in the variation of matrix from eutectic to hypoeutectic structure. The results of DSC (Differential Scanning Calorimetry) reveal that the Sn-8.55Zn-0.45Al solder has eutectic temperature at 197°C, but Ag-Zn compounds (AgZn3 and Ag5Zn8) melt above 300°C as Ag is added to the Sn-8.55Zn-0.45Al solder. An increase in Ag content results in little change in UTS (Ultimate Tensile Stress) and microhardness, but the elongation is prominently decreased. The elongation of the solders drops from 47.1% to 20% when Ag content increases from 0 to 3%. The results of TGA (Thermal Gravimetric Analysis) show that the weight gains at 250°C under O2 atmosphere descend in the order of Sn-9Zn>Sn-8.55Zn-0.45Al-(0.5wt%~3wt%)Ag>Sn-8.55Zn-0.45Al. This means that the incorporation of 0.45wt%Al enhances the oxidation resistance of Sn-Zn solder, while the weight gains of the Sn-8.55Zn-0.45Al-XAg solders increase as Ag was added into the Sn-8.55Zn-0.45Al solder. Auger depth profile shows that Zn and Al form an oxide film on the surface of Sn-9Zn and the Al-containing solders. The wetting results indicate that the wettability of Sn-8.55Zn-0.45Al-XAg solders decreases with increasing Ag content of solders. The Sn-Zn-Al-XAg solders containing low Ag content (0.5wt%) exhibit better wettability than the eutectic Sn-9Zn solder. Furthermore, it was also found that the wettability of Sn-Zn based solders on Cu substrate is better than that on Cu/Ni-P/Au substrate. The results of interfacial reaction indicate that Cu substrate forms Cu5Zn8 and CuZn5 with Sn-9Zn solder, and Al4.2Cu3.2Zn0.7 compound with Al-containing solders. However, it was detected that Cu6Sn5 forms at the Sn-9Zn/Cu interface and Cu5Zn8 forms at the Al-containing solders/Cu interface after aging for 1000 hours. In contacting with the Cu/Ni-P/Au substrate, Sn-9Zn solder forms AuZn3 compound, and the Al-containing solders forms Al2(Au,Zn) compound at the interface. After long time aging, the intermetallic compounds existing between solders and the Cu/Ni-P/Au metallization layers almost do not grow. It was found that the inter-diffusion between solders and Cu/Ni-P/Au is slower than that with Cu under aging. Furthermore, the additions of Ag to Sn-8.55Zn-0.45Al solder result in the formation of AgZn3 particles at the interface. This present work also investigated the reliability of the Sn-8.55Zn- 0.45Al-XAg solders under multiple reflow and thermal aging test. The results show that Sn-Zn based solder balls on Cu and Cu/Ni-P/Au substrates retain the shear strength under multiple reflow. Under thermal aging test, it was found that the shear strength of Sn-Zn based solder balls on Cu substrate decreases with increasing of aging time. However, the shear strength of Sn-Zn based solder balls on Cu/Ni-P/Au almost dose not change under thermal aging test. Thus, it was known that the Sn-Zn based solder balls on Cu/Ni-P/Au substrate exhibit better reliability than that on Cu substrate.
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Chung, Chun-lee, and 鍾君勵. "Steady Creep Analysis of Lead/Lead Free Solder Joints Using Deformation Kinetics." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/bhyp37.
Full textAbstract:
碩士國立成功大學
工程科學系碩博士班
92
This thesis discuss the behaviors(shear strain, shear stress) with various solder joints in different temperature which applied with deformation kinetic(Valanis and Lee,1981). Solder Joints,90Pb-10Sn ,63Sn-37Pb ,were tested with double beam specimens ,and solder joints Sn, Sn-3.5Ag, Sn-0.7Cu, Sn-3Ag-0.5Cu, and Sn-10In-3.1Ag were tested with simple shear test specimens. I changed the parameters of solder joint specimens step by step to find the optimal values. There are some different parameter values between Bulk specimens and solder joint specimens. At first, I Defined the parameter k1, and then k1 or cutoff shear stress.change with temperature. To Analysis the creep behaviors among those solder joints must be with the parameters k1 and the slop of energy barrier . By the way, I found the parameter the slop of energy barrier of Sn-10In-3.1Ag which was much different about another solder joints.
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Wang, Shau-wei, and 王韶韋. "Study of Metal Recovery from Lead-Free Solder Waste." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/48052828086862874981.
Full textAbstract:
碩士國立成功大學
材料科學及工程學系碩博士班
96
ABSTRACT This research mainly discussed the possibility of recovering metals from lead-free solder waste. Immediate lead-free solder was composed of Sn-Ag-Cu alloy. The experiment will aim at different chemical property of three metals to decide different procedures to separate the Sn, Ag and Cu, then further recovery individually. The experimental result showed that we can convert Sn2+ to H3SnO3 by using 10M HNO3 for the beginning, then used three different methods to recycle Ag+ form the remaining solution. The first method was adding NaCN, then recovery Ag by electrolysis, and the best condition was at 40oC, -1.5V v.s SCE for 3 hours to yield 99% recovery, 97.7% purity and 70% current efficiency. The second method was using copper wire to replace Ag+ at 25oC, 40 minutes to yield 98% recovery and 99.1% purity. The last method was adding 5MHCl to form AgCl first, then reduced AgCl to Ag by N2H4 (25oC, pH=10, 30 ml N2H4 dosage) to get 99% recovery and 99.3% purity, or by smelting with ratio of 40% Na2CO3 at 1000oC, 60 minutes can yield 83% recovery and 98.3% purity. In electrolytic process, we transformed AgCl to Ag(S2O3)23- or Ag(NH3)2+ complex ions. The best condition for Ag(S2O3)23- was at 25 oC , -0.6V v.s SCE for 6 hours to get 99% recovery, 98.3% purity, 74% current efficiency and for Ag(NH3)2+ was at 25 oC , -0.5V v.s SCE for 5 hours to get 99% recovery, 99.0% purity, 43% current efficiency.
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CHEN, HUEI-YI, and 陳慧憶. "Recycling of Lead-free Silver Containing Tin Solder Dross." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/06143225276478870290.
Full textAbstract:
碩士大葉大學
環境工程學系碩士班
96
ABSTRACT Due to the implementation of the act of “Restriction of Hazardous Substances Directive”, A lead-free silver-containing tin dross is produced in the electronic industry. This dross contains the valuable metals of silver (Ag) and tin (Sn). Thus, a series of methods of grinding, screening, leaching, pH adjustment, replacement, precipitation, electric wining and ion exchange are adopted in this study to recover the metals of Ag and Sn from lead-free silver-containing tin dross. The result of this study reveals that the dross was ground to a size of -50 mesh and subjected to a leaching condition of 4N HNO3, 700C, 2 hours and 5g/50ml to reach leaching recovery of 100%, 100% and 0.027％ for Ag, Pb and Sn, respectively. After filtration, the obtained solid is a salable high purity tin oxide. The pH of obtained leaching solution is adjusted to 2 by adding NH4 to precipitate all the Sn which contained in the solution. Then, 100% Ag and 86.67% Pb which remained in the solution are precipitated by adding N2H4．H2O. The collected Ag and Pb containing precipitate was washed by 5M HCl in 700C for 15 minutes and by water in 270C for another 15 minutes. The washed precipitate was then melted at 10000C together with boric acid (H3BO3) to obtain a marketable silver ingot. The Pb which remains in the solution can be removed by adding H2SO4 to form a precipitate of PbSO4.
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Lun, Lin Chun, and 林群倫. "The Application of Lead Free Solder in Electronic Packaging." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/60131142328819507381.
Full textAbstract:
碩士國立東華大學
材料科學與工程研究所
89
The purpose of this research is focused in an important issue, the substitute of traditional Pn-Sn solders in electronic packaging. The use of lead in solder alloys will be gradually prohibited in advanced environmental regulations due to its damage to human’s brain, neural system, liver and kidney. In this study, Sn is alloyed with many other elements, e.g. Zn, Bi, Au, Ag, In … etc. Based on phase diagrams, many binary eutectic compositions are consistent with the requirements in electronic packaging, for instance: 91Sn9Zn (199oC), 57Sn43Bi (139oC), 90Sn10Au (217oC), 96.5Sn3.5Ag (231oC) and 48.3Sn51.7In (120oC). This study is concentrated on Sn-Zn-In-(Ag) and Sn-Bi-Ag-In solder systems. First, the master alloy was produced by vacuum arc remelting. Differential scanning calorimeter (DSC) was used to measure the melting range of alloys in order to find solder alloys with the melting temperature range close to currently used Pb-Sn solders. Sessile drop experiments, thermal expansion coefficient measurements and microstructural analyses of solders were performed. The sessile drop experiment was made by using Au coated electroless Ni plated Cu substrate with no flux addition in accordance with BGA specification. The furnace was heated by a tungsten filament to the specified temperature for 20 minutes under vacuum (<5*10-2 torr), and the soldered specimen was subsequently aged at 90oC for certain time periods. The thickness of interfacial intermetallics after aging was measured by SEM. Finally, the phase was analyzed by either EDS or EPMA. According to the experimental observations, both melting point and wettability of 76Sn-9Zn-15In solder are superior to other Sn-Zn based solders. However, huge amount of zinc oxide in its matrix after aging results in brittle fracture of the interface. The wettability and melting temperature of Sn-Bi-Ag-In solders are in accordance with specifications in electronic packaging. The difference in thermal expansion coefficients between solders and electroless Ni plated substrate is much smaller than that in Pb-Sn solders. Therefore, further study will be made in the future. Keywords: soldering, tin alloys, interface, microstructure, thermal analysis
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Kuo, Shih-Ming, and 郭世明. "Electromigration in Eutectic Sn-9Zn Lead-Free Solder Joints." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/75342160294958890522.
Full textAbstract:
博士國立成功大學
材料科學及工程學系碩博士班
97
The purpose of this research is to investigate the electromigration (EM) behavior of metallic atoms in Sn-9Zn alloy. It also investigated the effect of electromigration on the interfacial reaction, the microstructural evolution of Sn-rich phase and Zn-rich phase, and the lattice orientation of the Zn-rich crystals in a Cu/Sn-9Zn/Cu sandwich structure. The reorientation and recrystallization behaviors of dispersed Zn second phases in Sn-9Zn alloy upon electromigration was also proposed in this study. Electromigration resulted in the consumption of Cu from the cathode which migrated to the anode and formed Cu5Zn8 near the anode in bulk solder. The average consumption rate of Cu on the cathode side was much faster than that of Cu on the anode side. The occurrences upon electromigration (EM) shows significant polarity effect on the nucleation and growth rate of the IMCs (��-Cu5Zn8, Cu6Sn5). Upon current stressing, the growth rate of the Cu-Zn intermetallic compound (��-Cu5Zn8) at the cathode interface was much faster than that at the anode. However, the nucleation and growth of the Cu6Sn5 IMC at the anode interface were enhanced, though retarded at the cathode, under the influence of electric current. The growth of the Cu6Sn5 phase, which nucleated at the anodic Cu5Zn8/Cu interface into the anodic Cu layer, was ascribed to the grain-boundary migration of Sn induced by electromigration. Consequently, the anodic Cu6Sn5/Cu interface was induced to move toward the anodic Cu due to electromigration. The formation of hillocks in the middle of bulk solder was ascribed to the compressive stress driven by electromigration and IMC formation. The electromigration results in void formation at the IMC/solder interface regardless of the electron flow direction. There is difference in the morphology and dimension of voids at the two ends of the solder (cathode and anode). Relatively large voids (rod shape) were formed at the cathode, yet small needle-like voids were formed at the anode. Nevertheless, fewer void was seen at the solder/IMC interface after thermal aging. Before current stressing, the fine dispersed Zn-rich phases randomly distribute in the matrix. The needle Zn-rich phase of the Sn-9Zn eutectic structure converts to equi-axial crystals after aging at 100oC for 24 hours (As prepared specimen) or at 130oC for 230 hours. Notably, the random texture of the Zn-rich phase crystals became laterally aligned after current stressing for 230 hours. The electrical current stressing converts the equi-axial Zn grains to longitudinal thin sheet or thin prism sheet crystals. XRD analysis showed that the reorientation of the second phase Zn-rich crystals was induced by electric current. The Zn-rich phase grew with a preferred orientation of (0002) upon current stressing. The remarkable difference in peak intensity between (0002) and (10 0) after 230 hours of current stressing showed that the thin sheet prism crystals of the Zn phase exhibit preferred orientation or even grow to single crystal. However, the Zn phase exhibits both (10 0) and (0002) lattice planes with close intensity upon aging at 130oC for up to 230 hours. TEM analysis showed that electromigration resulted in the recrystallization of the equiaxial Zn-rich phase crystal into a single crystal composed of the close-packed basal plane of the hexagonal Zn phase. The Zn poly-crystal of aged Sn-9Zn alloy recrystallized under electromigration to form a thin prism sheet crystal of basal plane unit with (0001) preferred orientation. The mobility of the semicoherent interface is much smaller than that of the incoherent interface. Consequently, the electromigration of Zn within the Zn phase gave rise to the formation of the thin prism sheet crystals. The electromigration behavior induced the continuing movement of the Zn atoms towards the incoherent interface which synergizes the two dimensional growing behavior of the grains and thus facilitated the formation of prism sheet crystals with the preferred [0001] orientation.
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Cheng-HsunLin and 林政勳. "Reliability Analysis of FC-PBGA Lead Free Solder Ball." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/62857488848907305352.
Full textAbstract:
碩士國立成功大學
機械工程學系
104
This master's thesis uses finite element software ANSYS15.0 to analyze the Filp-Chip Plastic Ball Grid Array packaging (FC-PBGA) which minify substrate and solder ball under accelerated thermal cycling loading. We will observe the thermal mechanical behaviors of the solder balls and research the fatigue life. In this simulation, we use ANSYS to establish the FC-PBGA model, and apply different material parameters in components to finish meshing. After that, we applied thermal Cycling Test (TCT) loads and observed the plastic strain range of the solder ball during TCT loads. Therefore, we used the Coffin-Manson equation to predict the fatigue life and reliability of the solder ball.
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Yu, Wei-Yi, and 余威儀. "Solderability study for Ni-Pd plated lead frame Vs lead-free solder paste." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/89293111384578834216.
Full textAbstract:
碩士國立臺灣科技大學
機械工程系
92
The electronic industry is moving towards Lead-free product and Green Policy to provide a better environment for our children. This drive has highlighted the fact that the industry has not arrived at a decision for Lead-Free component finishes. There are many approaches to replace current Sn-Pb finish such as pure Tin, Sn-Ag, Sn-Bi, Sn-cu solder plating and Ni-Pd-Au pre-plated lead frame which was promoted by Texas Instruments. These solder alloys have different melt point and require different range of IR profile and peak temperature. As the result of no world wide standard available up to date and IC makers in the world are moving in different approaches, all these makes a difficult position to PCB assembly processes — an uniform IR profile to fit all kind of components. This may induce reliability risk for end customer. The purpose of this study is to evaluate solder joint strength in different finished type of lead frame versus different IR profile and different soldr paste in PCB assembly. The majority will be Texas Instruments’ Ni-Pd-Au pre-plated lead frame which has better process window in trim-Form process against plating solder build up in Trim-Form tooling, electrical test socket, as resulting in pin-to-pin short.
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Lu, Chi-Ming, and 呂繼明. "Study of flux to lead-free solder and substrate relation." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/63534811297774723520.
Full textAbstract:
碩士義守大學
電子工程學系碩士班
97
We study the effects of commercial flux (A to D) on intermetallic compound (IMC) between Sn-Ag-Cu soldering ball and Ni-Au plated substrate. Several findings are uncovered after the examination of IMC thickness, ball-shear-force and ball-pull-force tests. (1) Flux appears to have no influence on the major ingredient of (Cu,Ni)6Sn5. (2) Of the same annealing condition, flux D yields the IMC that has the thinnest IMC of average 0.95?m. (3) That IMC also has the strongest ball-shear-force at 1313g. (4) It also has the largest ball-pull-force at 1895g. Overall, it is concluded that flux D is the best amount the four species tested.
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LIN, PAO-HSUAN, and 林保璇. "Electromigration behaviors of “XSn4” compounds in lead-free solder systems." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/6w3akp.
Full textAbstract:
碩士國立中正大學
化學工程研究所
107
In recent years, due to the miniaturization of electronic products. It was more important to choose the appropriate surface finish method in the pad. Electroless nickel immersion gold (ENIG) and Electroless nickel palladium gold (ENEPIG) were commonly used surface finish. Both of them would produce AuSn4 and PdSn4 phases during reflow and electromigration effects might happen under the current stressing. Therefore, this study investigated the same crystal structure AuSn4, PdSn4, NiSn4 and PtSn4 phases that were easily generated in solder joints. However, the above four intermetallic phases are collectively referred to as "XSn4" phases. The "XSn4" phases react at 5000A/cm2 and 180oC. The AuSn4 phase had the same phenomenon after 240 hours. Only the grains became larger, but still uniformly dispersed in the solder alloy. The grain size was increased due to the heat treatment of the ripening growth. The AuSn4 phase wasn’t affected by electromigration and had excellent electromigration resistance under current stressing. After energized for 240 hours, PdSn4 and PtSn4 were remained plate -like structure and didn’t aggregate due to electromigration. It could be seen that PdSn4 and PtSn4 phases had the same electromigration resistance, and there was no obvious heat treatment grain morphology transformation. In the ternary system, each element was more complicated under current stressing. In order to further explore the influence of the proportion of elemental components, this study prepared alloys related to the above binary systems. First, the influence of the intermetallic phases formed by three different compositions of Sn-Au-Ni alloy. In Sn-0.25Au-0.75Ni (wt.%) alloy, three IMCs were precipitated, including Ni3Sn4, (Ni,Au)Sn4, and (Au,Ni)Sn4 phases. The microstructure of the Sn-0.5Au-0.5Ni was similar to that of the Sn-0.25Au-0.75Ni, but only (Ni,Au)Sn4 and (Au,Ni)Sn4 were observed. Tiny (Ni,Au)Sn4 and (Au,Ni)Sn4 phases were precipitated in the Sn-0.75Au-0.25Ni. After the EM test in the Sn-0.25Au-0.75Ni, a large amount of Ni3Sn4 and (Ni,Au)Sn4 phases were accumulated at the downstream of electron flow. These observed results clearly demonstrated that the Ni atoms of Ni3Sn4 and (Ni,Au)Sn4 were easily affected by electromigration and migrated along the flow of electron currents. In contrast, the (Au,Ni)Sn4 in Sn-0.25Au-0.75Ni and Sn-0.5Au-0.5Ni alloys were uniformly dispersed in the solder matrix even after long-term current stressing, indicating that the (Au,Ni)Sn4 was less influenced by electromigration. However, the (Au,Ni)Sn4 in Sn-0.75Au-0.25Ni was greatly affected by electromigration. This could be attributed to the difference in Ni content of (Au,Ni)Sn4 phase. In the second part, the Sn-0.25Pd-0.75Cu, Sn-0.5Pd-0.5Cu and Sn-0.75Pd-0.25Cu alloys could precipitate (Cu,Pd)6Sn5 and (Pd,Cu)Sn4 phases, but the structural form of (Pd,Cu)Sn4 was different. The Sn-0.25Pd-0.75Cu alloy precipitated as a particulate (Pd,Cu)Sn4 phase, and the (Pd,Cu)Sn4 phase precipitated in Sn-0.5Pd-0.5Cu and Sn-0.75Pd-0.25Cu alloys were a plate-like structure. It's supposed to closely related with Pd content. The spherical structure (Pd,Cu) Sn4 didn’t easily block the diffusion path of Cu atoms, and a large amount of (Cu,Pd)6Sn5 phases were accumulated at the downstream of electron flow. In contrast, (Pd,Cu)Sn4 was a plate-like structure, which could greatly reduce the diffusion path of Cu atoms. However, the growth direction of the plate-like (Pd,Cu)Sn4 and the direction of current passing had a certain influence on the migration amount of resisting (Cu,Pd)6Sn5 phase. Finally, the Sn-Au-Cu alloy system, Sn-1Au-2Cu, Sn-1.5Au-1.5Cu and Sn-2Au-1Cu alloys could precipitate (Cu,Au)6Sn5 and (Au,Cu)Sn4 phases. They had similar results, (Cu,Au)6Sn5 phase under current stressing which were easily affected by electromigration and migrated along the flow of electron currents. The content of Au didn’t affect the rapid migration of (Cu,Au)6Sn5 phase. Although (Au,Cu)Sn4 wan’t easily affected by electromigration and uniformly dispersed in the alloy. But the extremely high solubility of (Cu,Au)6Sn5 and (Au,Cu)Sn4 phases. During heat treatment and current stressing, it was easy to find that (Au,Cu)Sn4 particles were attached to the outside in (Cu,Au)6Sn5 phases. Even diffused into (Cu,Au)6Sn5 phase to increase the Au content. Key words: Electromigration, Sn-Au-Ni alloys, Sn-Pd-Cu alloys and Sn-Au-Ni alloys
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Hsiu-JenPan and 潘修任. "Synthesis of nanosized lead-free solder particles by chemical reduction method." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/66192728251634022451.
Full textAbstract:
碩士國立成功大學
工程科學系碩博士班
98
Since industrial revolution, the trend of material development gradually becomes lighter, thinner, shorter and smaller. Now portable, non-toxic, recyclable properties are the keys. The trend of IC development has innovated into more connecting spots, smaller lead pitch, better performance, faster signal amd smaller form factors, as well as free-lead solder meterial. With the growing environmental concern, the latter is getting more attention. This research makes nano-sized Sn-3.5Ag-0.5Zn, lead-free solder alloy by using “Chemical Reduction Method”. Keu results are as follows. Under room temperature and atmospheric pressure, the Sn-3.5Ag-0.5Zn, lead-free solder alloy is synthesized by using SnSO4, AgNO3, Zn(NO3)2 as precursor and NaBH4 as reductant and PVP as protection agent during reaction. Through refining and processing of the Sn-3.5Ag-0.5Zn alloy first and then by cleaning, filtering and drying of the Sn-3.5Ag-0.5Zn precipitation, the alloy with sizes ranging from 10 to 30 nm can be obtained. In addition, through comparing the different reactions of Sn-3.5Ag-0.5Zn alloy by adding different quantity of NaBH4 and PVP. the significance for which NaBH4, PVP and temperature interplay is described.
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Chen, Jun-Yuan, and 陳俊元. "The Research of Lead-Free Solder Interfacial Reaction in UCSP Package." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/66308816564115066870.
Full textAbstract:
碩士義守大學
材料科學與工程學系
92
In this research, the basic properties、microstructures and the aging effects of Sn-0.7Cu、Sn-2.6Ag-0.6Cu、Sn-4.0Ag-0.5Cu lead-free solder balls and conventional Sn-Pb solder ball are investigated. In addition, commercial Ultra CSP 98L device with above mentimed solder balls and Sn-Pb、Sn-3.0Ag-0.5Cu、Sn-7Zn-Al（30-40ppm）paste are placed on OSP and NiAu PCB. After reflow, samples are gone through TCT and HTS reliability tests. DSC、SEM/EDX、EPMA/WDX are then utilized to study the mechanism of the IMC formation on the interface of the solder joints and the relations among the microstructures solder joint strength and the reliability. The results show that Sn-Pb solder ball consists of Sn-rich β phase and Pb-rich α phase solid solutions and both grains grown after long time aging. On the other hand, lead-free solder balls consist of Sn-rich β phase and eutectic IMC phases. Both sizes of β grains and IMC particles increase with aging time. The roundness of the solder balls after reflow decreases with increasing melting point of the solder materials. Due to the cyclying expansion and contraction of the TCT test, cracks are initiated on the interface of the solder ball and chip after 500 cycles and failed after 1000 cycles. Due to the thickness growth of the IMC on the OSP surface finished substrate, the joint strength decreases with increasing aging time of the HTS reliability test. For NiAu substrate, Ni layer acts as a barrier layer which in turn reduces the growth of the interfacial IMC. However, the gold embrittlement may occur which reduces the mechanical strength of the solder joint.
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Chen-HuiWang and 汪晨暉. "Low Cycle Fatigue of Sn-xAg-0.7Cu Lead-Free Solder Joints." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/83951590153323117145.
Full textAbstract:
碩士國立成功大學
機械工程學系
102
This research is aimed to investigate the effect of Ag content (0~3wt.%) on the microstructure and the low-cycle fatigue behavior of Sn-xAg-0.7Cu lead-free solder. Sn-xAg-0.7Cu solder in form of solder balls with 1.12±0.02 mm in diameter were fabricated. Solder balls were reflowed with Cu substrate in the form of single lap shear specimen, and then the low-cycle fatigue test were performed. Solder alloys SAC157, SAC207 show similar microstructure features whilst SAC307 solder alloy displays a very fine microstructure with intermetallic phases dense within the β-Sn matrix. The increase in silver content enhances the mechanical strength of the solder alloy as a result of an increase in volume fraction of Ag3Sn intermetallics. The fatigue life test reveals that fatigue life curve of the solder joint is absolutely different between barrel type and hourglass type. From SEM observations, it can be found that micro-cracks were first generated along the boundaries between these two phases. As a result of stress concentration effects, solder joints of barrel type would fail with IMC layer fracture mode except Sn-0.7Cu. However, solder joints of hourglass type would fail with solder fracture mode except Sn-3.0Ag-0.7Cu. The cracks generally propagated in a mixed mode and linked up to form large cracks and immediately lead to final failure. Sn-xAg-0.7Cu solder with silver addition by 1.5~2.0wt.% manifest already the better mechanical properties and fatigue behavior than that another Ag addition.
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Lin, Yu-Mu, and 林祐睦. "Microstructures and Mechanical Reliability of Sn-Ag-Cu Lead-Free Solder." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/60673406298149481821.
Full textAbstract:
碩士國立中興大學
材料科學與工程學系
96
Tin-silver-copper lead-free solder balls were welded on substrate pads by reflow soldering in this research. Different reflow temperatures were applied to study the effect of reflow temperature on the morphology, microstructure and mechanical reliability of solder joints. Experiment results showed that the reflow temperature did not have an obvious effect on the macroscopic appearance of the solder joints. The solder joints were well welded and exhibited a uniform structure. The largest wetting force increased with the reflow temperature and then stabilized at the temperatures above 240°C. From the observations of scanning electron microscopy, it was found that an intermetallic compound layer formed at the interfaces between the solder balls and the substrate pads. The thickness of the intermetallic compound layer increased with reflow temperature, as about 1.86 to 5.42 μm. The joint strength was measured by shear tests, and the average value under different reflow temperatures was 7.48 Nt/mm2, about 1.4 times the value of industry standard. As the reflow temperature increased to 240°C, the joint strength began to decrease, indicating that a higher reflow temperature resulted in the formation of a thicker intermetallic compound layer and consequently lowered the joint strength. Moreover, the hardness and elastic modulus of the eutectic and primary phases of the solder balls, the intermetallic compound layer and the nickel layer on the substrate pads were measured by nanoindentation tests, and their fracture behaviors were examined. The hardness and elastic modulus of the intermetallic compound layer were measured as about 6.49 and 193.46 GPa, respectively, and the highest among these four structures.