Eutectic Sn-Bi as an alternative to Pb-free solders

Hua, Fay; Mei, Z.; Glazer, J.

doi:10.1109/ectc.1998.678706

Cited by 55 publications

(32 citation statements)

References 5 publications

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“…Therefore, in addition of the Bi atoms to the Cu-Sn intermetallic, the interface between Cu 6 Sn 5 and the Bi containing Cu 6 Sn 5 phase may be disrupt the local atomic arrangement, weaken the interfacial bonding, and then cause interfacial embrittlement. This trend would suggest that Bi-containing layer (Cu 6 (Sn, Bi) 5 ) decreased the ductility of the intermetallic compound. Similar result was also reported by Liu and Shang.…”

Section: Resultsmentioning

confidence: 99%

“…In addition, the solder joints ex- hibited cracking within the intermetallic compound layer. The cracking occurred at the boundary between the region of the intermetallic compound with the Bi containing Cu 6 Sn 5 layer (Cu 6 (Sn, Bi) 5 ) and Cu 6 Sn 5 layer. According to the Sn-Bi binary phase diagram, 14) the solubility of Bi in the Sn-phase increase rapidly from negligible at room temperature to about 9 at%Bi at 120…”

Section: Resultsmentioning

confidence: 99%

“…Also, when compared to the Sn-Pb eutectic solder, the Sn-58Bi eutectic solder offers a higher strength and superior creep resistance but a lower ductility. [5][6][7][8][9] During soldering, the solder alloy melts and then reacts with the substrate to form intermetallic compounds at the joint interface. The growth of interfacial reaction products through solid-state aging in solder joints is of particular interest to the electronics industry.…”

Section: Introductionmentioning

confidence: 99%

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Interfacial Reactions Between Sn-58 mass%Bi Eutectic Solder and (Cu, Electroless Ni-P/Cu) Substrate

2002

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The growth kinetics of intermetallic compound layers formed between eutectic Sn-58Bi solder and (Cu, electroless Ni-P/Cu) substrate were investigated at temperature between 70 and 120 • C for 1 to 60 days. The layer growth of intermetallic compound in the couple of the Sn-58Bi/Cu and Sn-58Bi/electroless Ni-P system satisfied the parabolic law at given temperature range. As a whole, because the values of time exponent (n) have approximately 0.5, the layer growth of the intermetallic compound was mainly controlled by diffusion mechanism over the temperature range studied. The apparent activation energies of Cu 6 Sn 5 and Ni 3 Sn 4 intermetallic compound in the couple of the Sn-58Bi/Cu and Sn-58Bi/electroless Ni-P were 127.9 and 81.6 kJ/mol, respectively.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Interfacial Reactions Between Sn-58 mass%Bi Eutectic Solder and (Cu, Electroless Ni-P/Cu) Substrate

2002

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“…9) The 58Bi-42Sn alloy has received the greatest attention as a low melting temperature, Pb-free alternative to 63Sn-37Pb solder. [10][11][12][13] The melting temperature of the eutectic 58Bi-42Sn solder is 139 C. 14) The solderability properties of this composition are generally very good. 15) However, the 58Bi-42Sn alloy has several drawbacks.…”

Section: Introductionmentioning

confidence: 99%

Development of Sn-Based, Low Melting Temperature Pb-Free Solder Alloys

2004

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Low temperature, Sn-based Pb-free solders were developed by making alloy additions to the starting material, 96.5Sn-3.5Ag (mass%). The melting behavior was determined using Differential Scanning Calorimetry (DSC). The solder microstructure was evaluated by optical microscopy and electron probe microanalysis (EPMA). Shear strength measurements, hardness tests, intermetallic compound (IMC) layer growth measurements, and solderability tests were performed on selected alloys. Three promising ternary alloy compositions and respective solidus temperatures were: 91.84Sn-3.33Ag-4.83Bi, 212 C; 87.5Sn-7.5Au-5.0Bi, 200 C; and 86.4Sn-5.1Ag-8.5Au, 205 C. A quaternary alloy had the composition 86.8Sn-3.2Ag-5.0Bi-5.0Au and solidus temperature of 194 C. The shear strength of this quaternary alloy was nearly twice that of the eutectic Sn-Pb solder. The 66Sn-5.0Ag-10Bi-5.0Au-10In-4.0Cu alloy had a solidus temperature of 178 C and good solderability on Cu. The lowest solidus temperature of 159 C was realized with the alloy 62Sn-5.0Ag-10Bi-4.0Au-10In-4.0Cu-5.0Ga. The contributing factor towards the melting point depression was the composition of the solid solution, Sn-based matrix phase of each solder.

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“…However, at a much higher temperature near its melting point 42Sn-58Bi 0-7803-7038-4/01/$10.00 (C)2001 IEEE becomes softer and weaker than Sn-Pb. 42Sn-58Bi also shows a slower creep rate compared to 63Sn-37Pb [3].…”

Section: Introductionmentioning

confidence: 86%

Fluxless Sn-Bi-Au bonding process using multilayer design

Choe

Chuang²,

Lee

2001 Proceedings. 51st Electronic Components and Technology Conference (Cat. No.01CH37220)

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For many years lead-free solders have been a topic of interest in the packaging industry. One possible substitute material among the lead-free solders is eutectic Sn-Bi alloy (42Sn-58Bi) which has a melting temperature of 139°C. Earlier studies have shown that the conventional 63Sn-37Pb solder can be replaced by eutectic Sn-Bi in some low temperature applications.A fluxless alternative to the conventional soldering method is successfully developed using Sn-Bi-Au multilayer composite. The essence of this fluxless bonding technique comes from the spontaneous in situ formation of a thin AuSn 2 layer on the outer surface of the multilayer composite. This stable layer acts as a natural barrier against oxidation of the inner solder metals. The Sn-Bi-Au multilayer for bonding is prepared using a thermal evaporating vacuum chamber. The bonding temperature of this process ranges between 170°C and 180°C. The resulting as-solidified joint is made up of eutectic Sn-Bi alloy with small grains of AuSn 2 imbedded inside the solder.Sn-Bi joint cross-sections are examined to determine the quality of the joints. The process is found to be effective. SEM and EDX systems are used to examine the joint crosssection. The SEM images shows a uniform joint thickness of approximately 5µm. They also show the joint microstructure, exhibiting the usual lamellar structure of eutectic Sn-Bi alloy. EDX analysis also indicates the separation of the darker Snrich regions and the brighter Bi-rich regions.The fluxless feature, lead-free nature and processing temperature range of this bonding technique are particularly valuable for packaging photonic, optoelectronic, fiber optic, and MEMS devices and components.

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Eutectic Sn-Bi as an alternative to Pb-free solders

Cited by 55 publications

References 5 publications

Interfacial Reactions Between Sn-58 mass%Bi Eutectic Solder and (Cu, Electroless Ni-P/Cu) Substrate

Interfacial Reactions Between Sn-58 mass%Bi Eutectic Solder and (Cu, Electroless Ni-P/Cu) Substrate

Development of Sn-Based, Low Melting Temperature Pb-Free Solder Alloys

Fluxless Sn-Bi-Au bonding process using multilayer design

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