Journal ArticleDOI
Lead-free Solders in Microelectronics
Mulugeta Abtew,Guna S Selvaduray +1 more
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TLDR
The most widely used Pb-free solders have the eutectic composition as mentioned in this paper, which has been identified as a major factor affecting alloy selection, since this will have a major impact on the other polymeric materials used in microelectronic assembly and encapsulation.Abstract:
Practically all microelectronic assemblies in use today utilize Pb–Sn solders for interconnection. With the advent of chip scale packaging technologies, the usage of solder connections has increased. The most widely used Pb–Sn solder has the eutectic composition. Emerging environmental regulations worldwide, most notably in Europe and Japan, have targeted the elimination of Pb usage in electronic assemblies, due to the inherent toxicity of Pb. This has made the search for suitable “Pb-free” solders an important issue for microelectronics assembly. Approximately 70 Pb-free solder alloy compositions have been proposed thus far. There is a general lack of engineering information, and there is also significant disparity in the information available on these alloys. The issues involved can be divided into two broad categories: manufacturing and reliability/performance. A major factor affecting alloy selection is the melting point of the alloy, since this will have a major impact on the other polymeric materials used in microelectronic assembly and encapsulation. Other important manufacturing issues are cost, availability, and wetting characteristics. Reliability related properties include mechanical strength, fatigue resistance, coefficient of thermal expansion and intermetallic compound formation. The data available in the open literature have been reviewed and are summarized in this paper. Where data were not available, such as for corrosion and oxidation resistance, chemical thermodynamics was used to develop this information. While a formal alloy selection decision analysis methodology has not been developed, less formal approaches indicate that Sn-rich alloys will be the Pb-free solder alloys of choice, with three to four alloys being identified for each of the different applications. Research on this topic continues at the present time at a vigorous pace, in view of the imminence of the issue.read more
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Journal ArticleDOI
Effect of indium addition in Sn-rich solder on the dissolution of Cu metallization
Ahmed Sharif,Y.C. Chan +1 more
TL;DR: In this paper, the dissolution of the Cu pad of the ball-grid-array (BGA) substrate into the molten Sn-9%In-3.5%Cu and Sn-0.7%Cu alloys was investigated.
Journal ArticleDOI
Reactive wetting, evolution of interfacial and bulk IMCs and their effect on mechanical properties of eutectic Sn-Cu solder alloy.
Satyanarayan,K N Prabhu +1 more
TL;DR: It is recommended that future work should focus on evolving a standard procedure involving sequential assessment of wetting behavior, evolution of IMCs and mechanical properties as well as reliability of solder joints of the solder alloy.
Journal ArticleDOI
Structure and properties of Sn-Cu lead-free solders in electronics packaging
TL;DR: The evolution law of the internal structure of solder alloy/solder joint was analysed, and the model and theory describing the formation/growth mechanism of interfacial IMC were introduced and it was clear that with the addition of 0.05% Pr, the thickness of IMC layer decreases significantly and the formation of voids at the interface is inhibited.
Journal ArticleDOI
Mechanical properties of Sn–0.7Cu/Si3N4 lead-free composite solder
Mohd Arif Anuar Mohd Salleh,A.M. Mustafa Al Bakri,Flora Somidin,Noor Farhani Mohd Alui,Zainal Arifin Ahmad +4 more
TL;DR: In this article, various compositions of Sn-0.7Cu/Si3N4 lead-free composite solder were fabricated via the application of powder metallurgy (PM) techniques.
Journal ArticleDOI
The formation of nano-Ag3Sn particles on the intermetallic compounds during wetting reaction
TL;DR: In this paper, the morphologies of the intermetallic compounds (IMC) forming during wetting reaction between molten Sn 3.5Ag and pure Cu and Ni substrate were investigated.
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