Effect of variation of microstructure on the creep and rupture strengths of a Sn-3.5 % Ag lead-free solder alloy

Wu, Kepeng; Wade, Noboru; Yamada, Seiji; Miyahara, Kazuya

doi:10.3139/146.017933

Cited by 4 publications

(5 citation statements)

References 7 publications

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“…33 Given that the tensile strength of SnAgCu alloys increases with increasing cooling rate because of the production of finer and more closely spaced precipitates, both the cooling rate and the ball diameter affect the strength. [34][35][36] The microstructure and resulting solder joint properties can also vary strongly with subsequent aging, annealing, or thermal cycling. 37 The as -solidified microstructure will coarsen, even at room temperature, reducing the hardness and strength of the solders.…”

Section: Impact Of Dispersion/precipitation Evolution On Hardness Stmentioning

confidence: 99%

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Pb-Free Solder: New Materials Considerations for Microelectronics Processing

Børgesen

Bieler²,

Lehman

et al. 2007

MRS Bull.

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A single printed circuit board includes thousands, sometimes even hundreds of thousands, of solder joints. The failure of even a single solder joint is usually enough to compromise the functionality of an electronic device or system. PbSn solder had been the standard ma te rial for these joints until various regulations around the world began to limit Pb use. SnAgCu and related alloys are quickly replacing PbSn, but much still needs to be understood and controlled. None of the paradigms for understanding the mechanical response of PbSn alloys is applicable to lead -free alloys. Much of the surprising behavior of SnAgCu solder arises from the complex and fascinating nature of its solidification behavior. In this ar ticle, the impact of solidification on the microstruc ture and therefore the mechanical properties of these solder joints will be addressed in the context of microelectronics proc essing. The need for better simulations of SnAgCu solder behavior will also be examined. Notably, modelers will have to account for a variety of new parameter dependencies not previously considered.

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Section: Impact Of Dispersion/precipitation Evolution On Hardness Stmentioning

confidence: 99%

“…[21][22][23][24][25][26][27][28][29][30] For instance, crack propagation has been observed along large primary precipitates (see Figure 7) in SAC solder joints. Such precipitates are not found in SnPb alloys.…”

Section: Impact Of Dispersion/precipitation Evolution On Hardness Stmentioning

confidence: 99%

Pb-Free Solder: New Materials Considerations for Microelectronics Processing

Børgesen

Bieler²,

Lehman

et al. 2007

MRS Bull.

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“…[6][7][8] Not as much is known about the effects of cooling rate on microstructure, tensile, and creep behavior of Sn-rich solders. [9][10][11] Additionally, there appears to be a lack of consensus on the fundamental deformation mechanisms and effects of cooling rate on the tensile and creep behavior of the Sn-rich solders. 1,2,[9][10][11][12][13][14][15][16] This study presents a systematic evaluation of the effects of controlled cooling rates on creep behavior of a Sn-3.5Ag solder.…”

Section: Introductionmentioning

confidence: 98%

“…[9][10][11] Additionally, there appears to be a lack of consensus on the fundamental deformation mechanisms and effects of cooling rate on the tensile and creep behavior of the Sn-rich solders. 1,2,[9][10][11][12][13][14][15][16] This study presents a systematic evaluation of the effects of controlled cooling rates on creep behavior of a Sn-3.5Ag solder. A large portion of this study was directed to the understanding of the effects of cooling rate on the creep behavior of the solder, as well as to explaining the fundamental deformation mechanisms taking place during creep.…”

Section: Introductionmentioning

confidence: 98%

Effects of cooling rate on creep behavior of a Sn-3.5Ag alloy

Ochoa

Deng

Chawla

2004

Journal of Elec Materi

107

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The effect of cooling rate on microstructure and creep behavior of bulk, eutectic Sn-3.5Ag solders was studied. The cooling rate is an important processing variable that significantly affects the microstructure of the solder and therefore determines its mechanical behavior. Controlled cooling rates were obtained by cooling specimens in different media: water, air, and furnace, which resulted in cooling rates of 24°C/s, 0.5°C/s, and 0.08°C/s, respectively. The cooling rate decreased the secondary dendrite arm size and the spacing of the Sn-rich phase, as well as the morphology of Ag 3 Sn. The Sn-dendrite arm size and spacing were smaller at fast cooling rates, while slower cooling rates yielded a nearly eutectic microstructure. The morphology of Ag 3 Sn also changed from relatively spherical, at faster cooling rates, to needlelike for slower cooling. The effect of cooling rate on creep behavior was studied at 25°C, 60°C, 95°C, and 120°C. Faster cooling rates were found to increase the creep strength of the solder due to the refinement of the solder microstructure. Stress exponents, n, indicated that dislocation climb was the controlling mechanism. Activation energies, for all cooling rates, indicated that the dominant diffusional mechanism corresponded to dislocation pipe diffusion of Sn. Grain boundary sliding (GBS) measurements were conducted, using both scanning electron microscopy (SEM) and atomic force microscopy (AFM). It was observed that GBS had a very small contribution to the total creep strain.

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“…The present authors have also performed research on the creep and rupture behaviors of Cu wire/solder-joint specimens of Sn-3.5% Ag and Sn-0.5% Cu alloys and compared the results with those of the test specimens cut from the same alloy ingots. [5][6][7] …”

Section: Introductionmentioning

confidence: 98%

Creep and rupture behavior of Cu wire/lead-free solder-alloy joint specimen

Aoyama

Wade³

et al. 2003

Journal of Elec Materi

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Creep and rupture behavior of Cu wire/lead-free solder-alloy joint specimens have been investigated using Sn-3.5% Ag and Sn-0.5% Cu alloys. A Sn-37% Pb solder alloy is also used as a reference material. The present authors have fabricated a creep-rupture testing machine for Cu wire/solder-alloy joint specimens, performed creep and rupture tests at 303 K and 403 K, analyzed the characteristics of the creep and rupture behavior, and compared these to test specimens cut from the same alloy ingots. It is also found that the rupture strength of the joint specimens is related to the rupture strength of the alloys.

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Effect of variation of microstructure on the creep and rupture strengths of a Sn-3.5 % Ag lead-free solder alloy

Cited by 4 publications

References 7 publications

Pb-Free Solder: New Materials Considerations for Microelectronics Processing

Pb-Free Solder: New Materials Considerations for Microelectronics Processing

Effects of cooling rate on creep behavior of a Sn-3.5Ag alloy

Creep and rupture behavior of Cu wire/lead-free solder-alloy joint specimen

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