FCT Assembly to Present New Technology for Paste Printing at the SMTA Toronto Expo

EMSNow: FCT Assembly will exhibit at the upcoming SMTA Toronto Expo and Tech Forum, scheduled to take place Thursday May 16, 2013 at the Sheraton Toronto Airport Hotel & Conference Centre in Ontario. Keith Howell, Technical Director at Nihon Superior, will hold a technical presentation on nano silver replacement for high lead solders in semiconductor junctions. Keith works closely with the FCT Assembly team, a licensee for Nihon Superior'sSN100C.

FCT Assembly has developed the world's most advanced stencil technology for solder paste printing.  The technology is comprised of a specifically engineered nano coating applied over its proven Slic™ stencil. The technology is surprisingly cost-effective, making improved yields available to all levels of the industry. The technology can be used with current assembly equipment and processes.

The new NanoSlic™ stencil is based on the proven Slic™ stencil with its advanced foil composition and FCTA's state-of-the-art laser cutting process. Then, a permanent nano coating is applied that is based on a revolutionary chemistry platform called Hybrid-T Technology™. The coating imparts a highly hydrophobic and oleophobic surface to the bottom of the stencil and aperture walls. The robust coating should last the life of the stencil.

Using the newly developed NanoSlic™ coating system, NanoSlic™ is sprayed onto the stencil surface and aperture walls, reducing bridging and significantly improving paste release, permitting consistent printing of the smallest area ratios. The technology will be applied by FCT Assembly in its various locations. The user will see following benefits immediately: reduced bridging, reduced underside cleaning, improved paste release and improved yields.

An added benefit, the NanoSlic™ coating, is environmentally friendly. It does not use any Perfluorooctanoic acid (PFOA), a toxic substance currently being investigated by the EPA.

www.fctassembly.com.

Bi-Sn-BASED HIGH-TEMPERATURE SOLDER ALLOY

Espacenet: A high-temperature solder alloy is a Bi-Sn based solder alloy containing at least 90 mass % of Bi, further containing 1 - 5 mass % of Sn, at least one element selected from Sb and/or Ag each in an amount of 0.5 - 5 mass %, and preferably further containing 0.0004 - 0.01 mass % of P.

EP2589459  (A1)  -  Bi-Sn-BASED HIGH-TEMPERATURE SOLDER ALLOY
Inventor(s):     UESHIMA MINORU [JP]; INAGAWA YOSHIMI [JP]; TOYODA MINORU [JP] +
Applicant(s):     SENJU METAL INDUSTRY CO [JP] +
Classification:    
- international:     B23K1/00; B23K35/26; C22C12/00; H05K3/34; B23K101/40
- cooperative:     B23K1/0016; B23K35/264; C22C12/00; H05K3/3463; B23K2201/42; H05K3/3494;
Application number:     EP20110800638 20110617  

Microsemi Elected to Lead 'ELCOSINT' Team to Develop Material for High-temperature Electronics Applications

Microsemi Elected to Lead 'ELCOSINT' Team to Develop Material for High-temperature Electronics Applications (NASDAQ:MSCC):

Project Participants Include UK's National Physical Laboratory and Gwent Electronic Materials
ALISO VIEJO, Calif., Feb. 26, 2013 /PRNewswire/ -- Microsemi Corporation (Nasdaq: MSCC), a leading provider of semiconductor solutions differentiated by power, security, reliability and performance, today announced that it has been elected to lead the Electronic Component Sintered Interconnections (ELCOSINT) industry team in developing novel polymeric, sintered interconnection materials to replace high lead (Pb) content materials and further increase the operating temperature of electronic assemblies. These materials will be suitable for components subjected to extremely high operating temperatures of 250 degrees C or more, which often occur in market sectors such as aerospace and down hole drilling.
(Logo: http://photos.prnewswire.com/prnh/20110909/MM66070LOGO)
The three-year ELCOSINT project is partially funded by the Technology Strategy Board, an executive non-departmental public body established by the United Kingdom government to stimulate technology-enabled innovation. Microsemi will collaborate on the project with the UK's National Physical Laboratory, a world-leading center of excellence in developing and applying the most accurate measurement standards, science and technology available; and Gwent Electronic Materials LTD, a supplier of sophisticated and cost-effective electronics materials.
About the ELCOSINT Project
The multi-disciplinary ELCOSINT project team will develop the materials and manufacturing process for electronic component interconnection using nano-silver based materials to form joints between components and substrates. The technology will be compatible with standard microelectronics manufacturing processes, and replacing high-lead solder with nano-silver based materials will enable improved performance in harsh environments. It is also more environmentally friendly.
A high temperature sensor amplifier demonstrator will be designed and produced that will allow the characterization, assessment and qualification of the developments to enable rapid production of reliable, robust electronic systems.
About Microsemi
Microsemi Corporation (Nasdaq: MSCC) offers a comprehensive portfolio of semiconductor and system solutions for communications, defense & security, aerospace and industrial markets. Products include high-performance, radiation-hardened and highly reliable analog mixed-signal integrated circuits, FPGAs, SoCs and ASICs; power management products; timing and voice processing devices; RF solutions; discrete components; security technologies and scalable anti-tamper products; Power-over-Ethernet ICs and midspans; as well as custom design capabilities and services. Microsemi is headquartered in Aliso Viejo, Calif. , and has approximately 3,000 employees globally. Learn more at www.microsemi.com.
Microsemi and the Microsemi logo are registered trademarks or service marks of Microsemi Corporation and/or its affiliates. Third-party trademarks and service marks mentioned herein are the property of their respective owners.
"Safe Harbor" Statement under the Private Securities Litigation Reform Act of 1995: Any statements set forth in this news release that are not entirely historical and factual in nature, including without limitation statements related to its leadership role in the Electronic Component Sintered Interconnections (ELCOSINT) industry team in developing novel polymeric, sintered interconnection materials to replace high lead (Pb) content materials and further increase the operating temperature of electronic assemblies, and its potential effects on future business, are forward-looking statements. These forward-looking statements are based on our current expectations and are inherently subject to risks and uncertainties that could cause actual results to differ materially from those expressed in the forward-looking statements. The potential risks and uncertainties include, but are not limited to, such factors as rapidly changing technology and product obsolescence, potential cost increases, variations in customer order preferences, weakness or competitive pricing environment of the marketplace, uncertain demand for and acceptance of the company's products, adverse circumstances in any of our end markets, results of in-process or planned development or marketing and promotional campaigns, difficulties foreseeing future demand, potential non-realization of expected orders or non-realization of backlog, product returns, product liability, and other potential unexpected business and economic conditions or adverse changes in current or expected industry conditions, difficulties and costs of protecting patents and other proprietary rights, inventory obsolescence and difficulties regarding customer qualification of products. In addition to these factors and any other factors mentioned elsewhere in this news release, the reader should refer as well to the factors, uncertainties or risks identified in the company's most recent Form 10-K and all subsequent Form 10-Q reports filed by Microsemi with the SEC. Additional risk factors may be identified from time to time in Microsemi's future filings. The forward-looking statements included in this release speak only as of the date hereof, and Microsemi does not undertake any obligation to update these forward-looking statements to reflect subsequent events or circumstances.
MSCCP
SOURCE Microsemi Corporation

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New nanoalloys for high temperature soldering

New nanoalloys for high temperature soldering:


Nanowerk News) Removing lead from manufacturing processes and products is high priority for the EU. A European research programme has tackled the problem of high-temperature solders used in the electronics industry.
On soldering components on a printed circuit board, it is crucial that the joints do not remelt in subsequent soldering operations. The electronics industry is therefore inclined to use solder material containing a high percentage of lead with a higher melting point (300 °C and above).
One solution is to use so-called nanosolders based on tin-antimony (Sn-Sb) alloys. Nanoparticles have a lower melting point than the bulk substance. Funded by the EU, the project 'A chemical approach to lead-free nanosolders' (Nanosold) aimed to develop new lead-free high-temperature solders with Sn-Sb-M alloys. M is silver (Ag), copper (Cu) and nickel (Ni).
Concentrating on the two ternary alloy systems Sn-Sb-Ag and Sn-Sb-Cu, the Nanosold project investigated the thermodynamic properties, the sum of the features of the individual phases. The team used the so-called 'Computer coupling of phase diagrams and thermochemistry' (Calphad) method enabling the scientists to reliably predict the thermodynamic properties without experimental information.
To refine the phase relations in the Sn-Sb-Ni system, Nanosold used other complementary methods. These included powder X-ray diffraction, electron probe micro-analysis, scanning electron microscopy and differential thermal analysis.
A reduction in melting point of up to 11 °C was achieved using nanoalloys rich in Sn prepared by a chemical reduction method. Particle size was modified to be in the range of 50 to 150 nm which would translate into a size-dependent lowering of soldering temperature in any practical application.
Although there are further problems to be worked on, solder pastes based on nanoalloys would achieve a decrease in melting point. From an environmental point of view, the new nanoalloys remove a very toxic element from electronic appliances' manufacturing.
Source: Cordis



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Pb-free solder alloy mainly containing Zn

Espacenet - Bibliographic data:

There is provided a high-temperature Zn-based Pb free solder alloy having a melting point of approximately 300 to 400 DEG C and is excellent in wettability, joinability, workability and reliability. The Pb-free solder alloy mainly containing Zn consists of: 1.0 to 9.0 mass%, preferably 3.0 to 7.0 mass% of Al, 0.002 to 0.800 mass%, preferably 0.005 to 0.500 mass% of P, and a balance being Zn except for inevitable impurities incorporated during a manufacturing stage. The Pb-free solder alloy may include at least one of 0.3 to 4.0 mass% of Mg or 0.3 to 3.0 mass% of Ge.

Page bookmark TW201228764  (A)  -  Pb-free solder alloy mainly containing Zn
Inventor(s): ISEKI TAKASHI [JP] +
Applicant(s): SUMITOMO METAL MINING CO [JP] +
Classification:
- international: B23K35/28; C22C18/04
- European: B23K35/28B; H05K3/34F1
Application number: TW100140229 20111104
Priority number(s): JP20100274134 20101208
Also published as: WO2012077415  (A1)   JP2012121053  (A)


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New patents for Bi rich solders

Sumitomo have applied for patents on a novel lead free solder alloy, consisting predominantly of Bi with the major addition of Zn.  Smaller amounts of Al & P are also added, as well as Cu in some instances. Claims for the alloy include a small residual stress during solidification, allowing for a high joint strength and high reliability.  It also claimed that it can suppress a reaction between Ni and Bi or diffusion of Ni when used to join Ni-containing electronic parts or substrates, and can withstand a high reflow temperature.

http://worldwide.espacenet.com/publicationDetails/biblio?CC=WO&NR=2012120733A1&KC=A1&FT=D&DB=EPODOC&locale=en_EP&date=20120913&rss=true

http://worldwide.espacenet.com/publicationDetails/biblio?CC=TW&NR=201204502A&KC=A&FT=D&DB=EPODOC&locale=en_EP&date=20120201&rss=true


Senju have also applied for a patent for a high temperature solder alloy containing 90% Bi with additions of Sn, Sb, Ag & P.

http://worldwide.espacenet.com/publicationDetails/biblio?CC=TW&NR=201213552A&KC=A&FT=D&DB=EPODOC&locale=en_EP&date=20120401&rss=true

Current problems and possible solutions in high-temperature lead-free soldering

Lead use in solders for high-temperature applications (>85% lead, T _M≈250-350 °C) is still exempt in RoHS2, but the search for substitutes has been ongoing for a decade without finding a viable solution.  This article attempts to map the current situation with a short review of current legislation, requirements for a substitute alloy and describing some possible existing solutions.


http://www.scopus.com/record/display.url?eid=2-s2.0-84862182829&origin=inward&txGid=jCyxNaWvGqBFwEEMqY-XDsH%3a6


Journal of Materials Engineering and Performance
Volume 21, Issue 5, May 2012, Pages 629-637
Current problems and possible solutions in high-temperature lead-free soldering  ( Review )
Kroupa, A.a , Andersson, D.b, Hoo, N.c, Pearce, J.c, Watson, A.d, Dinsdale, A.e, Mucklejohn, S.f
a  Institute of Physics of Materials, AS CR, Zizkova 22, 61662 Brno, Czech Republic
b  Swerea IVF, Mölndal, Sweden
c  ITRI Ltd., Curo Park, St. Albans, United Kingdom
d  SPEME, University of Leeds, Leeds, United Kingdom
e  National Physical Laboratory, Teddington, United Kingdom
f  Ceravision Limited, The Mansion, Bletchley Park, MK3 6EB, United Kingdom

A composite solder alloy preform for high temperature Pb-free soldering applications

Scopus: High temperature Pb-free solder materials are needed in die attach, flip-chip packaging, power semiconductor and optical device packaging, etc. In this work, a special laminate composite preform has been developed for high temperature Pb-free soldering applications, where a melting temperature of 280 �C or higher is required. The laminate composite preform is composed of a high-melting, ductile metal core layer and a low-melting solder coating layer at both sides of the core layer. During soldering, the core metal and the liquid solder layer together with the substrate metals to be bonded react to form high-melting intermetallic compound phases (IMCs) to consume the low-melting solder phase rapidly. The resultant solder joint consists of a ductile core layer sandwiched by the IMCs layers at substrate sides, with a much higher remelt temperature than the melting temperature of the initial solder alloy coating. The laminate composite structure in the solder joint increases strengths and fracture toughness. The microstructures, mechanical properties and reliability of the solder joints formed by use of the SnAg/Ag/SnAg composite preform are investigated for high temperature Pb-free soldering applications. Effects of the process variables on the microstructure and defects formation in the solder joints are also discussed in the paper


IBSC 2012 - Proceedings of the 5th International Brazing and Soldering Conference
2012, Pages 188-195
5th International Brazing and Soldering Conference, IBSC 2012;Las Vegas, NV;22 April 2012through25 April 2012;Code90195
A composite solder alloy preform for high temperature Pb-free soldering applications  ( Conference Paper )

Liu, W., Bachorik, P., Lee, N.-C.

Indium Corporation of America, Clinton, NY, United States

High-temperature solders development: A review

There has long been a requirement for the development of lead-free solder alloys for high-temperature applications  to replace lead-containing alloys which is becoming evermore pressing. This paper reviews recent research in to  replacement alloys, as well as traditional Pb–Sn alloys, collating relevant properties and identifying areas where further development is required. The main candidate alloys covered are derived from the Au–Sn, Au–Ge, Zn–Al, Zn–Sn, Bi–Ag and Sn–Sb alloy systems.

ScienceDirect.com - Microelectronics Reliability - Development of high-temperature solders: Review:

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Die-to-die bonding using copper pillars

EDN: In packaging applications for cellular electronics devices, the use of flip chip copper pillar bumps has been expanding due to its better shape, lesser thickness, smaller form factor, better performance and lower power consumption. Foundries and semiconductor manufacturers are actively evaluating this new technology as the chips are becoming complex and size is shrinking day by day which leads to higher pin count and large interconnect densities which can hamper manufacturability of the bump pad.

Synthesis of Au-Sn alloy nanoparticles for lead-free electronics with unique combination of low and high melting temperatures

Scopus : Au-Sn alloy nanoparticles (ANPs) with 16-67 wt% Sn were successfully synthesized in the size range of 2-10 nm using chemical reduction method. X-ray diffraction confirmed the formation of AuSn phase with hexagonal structure and was further validated by microscopy and spectroscopy techniques. Chemical reduction is a more scalable and economical technique relative to other synthesis methods for solder alloy particles; it can produce particles in nanoscale range and can be conducted at room temperature. A significant depression in the melting transition (starting from 187 'C) was observed for the Au-Sn ANPs relative to the bulk eutectic point (T m = 280 'C at 30% Au). Au-Sn nanoparticles offer a unique set of advantages as lead-free soldering material. In nanoparticle state, they can reflow at lower temperatures leading to less thermal stresses in adjacent electronic components during the manufacturing process. After the initial reflow and solder joint formation (bulk state), they can reclaim bulk Au-Sn properties including permanent high melting temperatures (up to 420 'C) which can potentially lead to superior thermal and mechanical performance suitable for high temperature electronic applications such as military and aerospace.

Reliability of Au-Ge and Au-Si Eutectic Solder Alloys for High-Temperature Electronics

Scopus: High-temperature electronics will facilitate deeper drilling accessing harder-to-reach fossil fuels in oil and gas industry. A key requirement is reliability under harsh conditions for a minimum continuous operating time of 500 h at 300°C. Eutectic solder alloys are generally favored due to their excellent fatigue resistance. Performance of Au-Ge and Au-Si eutectic solder alloys at 300°C up to 500 h has been evaluated. Nanoindentation results confirm the loss of strength of Au-Ge and Au-Si eutectic solder alloys during thermal aging at 300°C, as a result of grain coarsening. However, the pace at which the Au-Ge eutectic alloy loses its strength is much slower when compared with Au-Si eutectic alloy. The interfacial reactions between these eutectic solder alloys and the underbump metallization (UBM), i.e., electroless nickel immersion gold (ENIG) UBM and Cu/Au UBM, have been extensively studied. Spalling of Au ₃Cu intermetallic compound is observed at the interface between Au-Ge eutectic solder and the Cu/Au UBM, when aged at 300°C for 500 h, while the consumption of ENIG UBM is nominal. Unlike the Au-Si solder joint, hot ball shear testing at high temperature confirmed that the Au-Ge joint on ENIG UBM, when aged at 300°C for 500 h, could still comply with the minimum qualifying bump shear strength based on the UBM dimension used in this work. Thus, it has been determined that, among these two binary eutectic alloys, Au-Ge eutectic alloy could fulfill the minimum requirement specified by the oil and gas exploration industry.


Journal of Electronic Materials
2012, Pages 1-11
Reliability of Au-Ge and Au-Si Eutectic Solder Alloys for High-Temperature Electronics  ( Articles not published yet, but available online Article in press About articles in press (opens in a new window) )

Chidambaram, V. , Yeung, H.B., Shan, G. 

Institute of Microelectronics, ASTAR (Agency for Science, Technology and Research), 11 Science Park Road, Science Park II, Singapore, 117685, Singapore

Co-electrodeposited graphite and diamond-loaded solder nanocomposites as thermal interface materials

Scopus: This paper describes a novel co-electrodeposition process to form thin bonding structures based on solder-graphite and solder-diamond nanocomposites for thermal interface materials (TIM). Using this novel processing route, inorganic nanoparticles can be co-plated along with a solder matrix to form unique nanocomposite structures with much enhanced thermal conductivity, engineered thermomechanical properties such as coefficient of thermal expansion (CTE), strength and fatigue resistance, while enabling the benefits of electroplating such as thin film and fine-pitch processing, low-temperature deposition and compatibility with semiconductor and packaging infrastructure. Si-Si and Cu-Cu bonding were demonstrated with these solder nanocomposites having high graphite loading. Pressure-assisted bonding enhanced solder wetting on nanoparticles and improved the bonding characteristics


Proceedings - Electronic Components and Technology Conference
2010, Article number 5490744, Pages 1708-1712
60th Electronic Components and Technology Conference, ECTC 2010;Las Vegas, NV;1 June 2010through4 June 2010;Category number10CH38220;Code81304
Co-electrodeposited graphite and diamond-loaded solder nanocomposites as thermal interface materials  ( Conference Paper )
Reddy, G.P.a, Raj, P.M.a , Nataraj, N.a, Rajesh, P.M.a, Jha, G.a, Choudhury, A.a, Kumbhat, N.a, Tummala, R.a, Brese, N.b, Toben, M.b, Szöcs, E.b  
a  3D Systems Packaging Research Center, Georgia Institute of Technology, Atlanta, GA 30332-0560, United States
b  Dow Chemical Company, 455 Forest St., Marlborough, MA 01752, United States

LinkedIn:

Any break through in high temp resistant Pb free solder for power electronics ????
March 27, 2011


Nikhil Kolhatkar • Mixing C-Nanotubes or Nano-Diamonds with solder has been researched to provide good thermal characteristics. It is a costly affair though but with a remarkable results.

Nano-Ag would be the best choice considering better thermal , electrical and manufacturing cost for power electronics.

Synthesis of Au–Sn alloy nanoparticles for lead-free electronics with unique combination of low and high melting temperatures

ScienceDirect.com: Au–Sn alloy nanoparticles (ANPs) with 16–67 wt% Sn were successfully synthesized in the size range of 2–10 nm using chemical reduction method. X-ray diffraction confirmed the formation of AuSn phase with hexagonal structure and was further validated by microscopy and spectroscopy techniques. Chemical reduction is a more scalable and economical technique relative to other synthesis methods for solder alloy particles; it can produce particles in nanoscale range and can be conducted at room temperature. A significant depression in the melting transition (starting from 187 °C) was observed for the Au–Sn ANPs relative to the bulk eutectic point (Tm = 280 °C at 30% Au). Au-Sn nanoparticles offer a unique set of advantages as lead-free soldering material. In nanoparticle state, they can reflow at lower temperatures leading to less thermal stresses in adjacent electronic components during the manufacturing process. After the initial reflow and solder joint formation (bulk state), they can reclaim bulk Au-Sn properties including permanent high melting temperatures (up to 420 °C) which can potentially lead to superior thermal and mechanical performance suitable for high temperature electronic applications such as military and aerospace.


Microelectronics Reliability
Available online 8 May 2012
In Press, Corrected Proof — Note to users
Salomeh Tabatabaeia, Ashavani Kumara, Haleh Ardebilib, , , Peter J. Loosa, Pulickel M. Ajayana
a Department of Mechanical Engineering and Materials Science, Rice University, Houston, TX 77005, USA
b Department of Mechanical Engineering, University of Houston, TX 77004, USA
Received 1 December 2011. Revised 15 April 2012. Accepted 16 April 2012. Available online 8 May 2012.

Any break through in high temp resistant Pb free solder for power electronics ???? | LinkedIn

LinkedIn: Any break through in high temp resistant Pb free solder for power electronics ????
March 27, 2011


Manoj Raghav likes this
4 comments

Follow Shahid
Shahid Mehmood • Use of nano silver paste through sintering process might be a better alternative if high temperature is the requirement
5 months ago• Like1

Follow Craig
Craig Hillman • Jaspreet,

At what temperature? The current approach seems to be developing different solutions for different temperature ranges.
5 months ago• Like

Follow Shahid
Shahid Mehmood • Well, theoritically the bond formed as a result of sintering of nano silver paste would be stable below 961oC. But as a rule of thumb for solders joint can work below the homologous temperature which is 0.8Tm of the solder. In the case of nano silver paste it is 768oC.

Below is the link to the paper where you can find more information:
http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=5730660

Hope it works
5 months ago• Like

Follow karthik
karthik vijayamadhavan • what about the pressure required and subsequent wire-bond reliability with nano-Ag sintering?

Development of high-temperature solders: Review

Scopus: The development of lead-free solder alloys for high-temperature applications is required to meet increasing demands for reliable replacements for lead-containing alloys. This paper provides a review of recent research on suitable replacement alloys, as well as traditional Pb-Sn alloys, collating relevant properties and identifying areas where further development is required. The main candidate alloys covered are derived from the Au-Sn, Au-Ge, Zn-Al, Zn-Sn, Bi-Ag and Sn-Sb alloy systems. Each of these systems is discussed with respect to the advantages and disadvantages associated with their use in soldering applications. It is concluded that further development of alloys suitable for high-temperature lead-free soldering applications is required


Microelectronics Reliability
2012


Zeng, G. ,McDonald, S.,Nogita, K.  
School of Mechanical and Mining Engineering, The University of Queensland, Brisbane, Australia

ITRI Co-authored review of high temperature solders

SpringerLink: The substitution of lead in the electronics industry is one of the key issues in the current drive towards ecological manufacturing. Legislation has already banned the use of lead in solders for mainstream applications (T M≈220'C), but the use of lead in the solders for high-temperature applications (>85% lead, T M≈250-350'C) is still exempt in RoHS2.

The search for proper substitutes has been ongoing among solder manufacturers only for a decade without finding a viable low cost alternative and is the subject of intensive research.

This article tries to map the current situation in the field of high-temperature lead-free soldering, presenting a short review of current legislation, requirements for substitute alloys, and finally it describes some existing solutions both in the field of promising new materials and new technologies.

Currently, there is no drop-in replacement for lead-containing solders and therefore both the new materials and the new technologies may be viable solutions for production of reliable lead-free joints for high-temperature applications.

BiZnCu solder patent Sumitomo

espacenet: Disclosed is a Pb-free solder alloy for use under high-temperature conditions, which has strength at a level required for the bonding between an electronic component and a substrate and also has excellent wettablity and processability. Specifically disclosed is a Pb-free solder alloy for use under high-temperature conditions, which comprises 0.4 to 13.5 mass% inclusive of Zn, 0.05 to 2.0 mass% inclusive of Cu, not more than 0.500 mass% of P, and a remainder made up by Bi and unavoidable impurities. The Pb-free solder alloy may additionally contain 0.03 to 0.7 mass% inclusive of Al.

Sumitomo patent: WO2012002147 (A1) ― 2012-01-05

BiSn + Sb/Ag Solder patent Senju

espacenet: A high-temperature solder alloy comprising a Bi-Sn-based solder alloy containing 90 mass% or more of Bi, wherein the Bi-Sn-based solder alloy additionally contains 1 to 5 mass% of Sn and 0.5 to 5 mass% of at least one element selected from Sb and/or Ag, and more preferably additionally contains 0.0004 to 0.01 mass% of P.

Senju patent: WO2012002173 (A1) ― 2012-01-05

SnNi solder for flip chip bonding

espacenet: Solder used for flip chip bonding inside a semiconductor package was a Sn-Pb solder such as a Pb-5Sn composition. Lead-free solders which have been studied are hard and easily form intermetallic compounds with Sn, so they were not suitable for a flip chip connection structure inside a semiconductor package, which requires stress relaxation properties.

This problem is dissolved by a flip chip connection structure inside a semiconductor package using a lead-free solder which is characterized by consisting essentially of 0.01 - 0.5 mass percent of Ni and a remainder of Sn. 0.3 - 0.9 mass percent of Cu and 0.001 - 0.01 mass percent of P may be added to this solder composition.

Senju Patent: KR20110010695, 2011-02-07