Influence of bismuth on the solidification of Sn-0.7Cu-0.05Ni-xBi/Cu joints

Belyakov, S. A.; Xian, J.W.; Sweatman, Keith; Nishimura, Tetsuro; Akaiwa, Tetsuya; Gourlay, C.M.

doi:10.1016/j.jallcom.2016.12.404

Cited by 43 publications

(21 citation statements)

References 66 publications

(77 reference statements)

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“…Sn-0.7Cu/Cu and Sn-0.7Cu-0.05Ni/Cu) result in multiple independent grains growing from the IMC layer [65,85]. Therefore, there may be opportunities to engineer the substrate to control the number of βSn nucleation events and this approach is likely to be most effective when solute and nucleation sites are combined.…”

Section: Outlook For the Grain Refinement Of Solder Jointsmentioning

confidence: 99%

Grain refinement of electronic solders: The potential of combining solute with nucleant particles

Shang

Belyakov

et al. 2017

Journal of Alloys and Compounds

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Sn-Ag-Cu electronic solder joints typically solidify from a single nucleation event producing either a single βSn grain or twinned grains. With so few and variable βSn orientations, each joint is mechanically unique due to the anisotropy of tetragonal βSn. Here we explore the potential of increasing the number of βSn orientations in solder joints by promoting heterogeneous nucleation during solidification. It is shown that large (60 g) samples can be grain refined effectively by combining growth restricting solute with potent heterogeneous nucleant particles introduced by alloying additions of Zn, Ti, Co, Ir, Pd, or Pt. These mechanisms are discussed with reference to the grain refinement of structural casting alloys.In 500 μm solder balls, these grain refinement approaches were less effective and a relatively high cooling rate of 17 K/s combined with solute and nucleant particles were required to trigger multiple nucleation events. With this approach, up to 12 independent grains formed in 500 μm balls of Sn-3Ag-0.5Cu alloyed with Pt, Co, or Ti, compared with one independent grain in balls without nucleant particle additions.

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Section: Outlook For the Grain Refinement Of Solder Jointsmentioning

confidence: 99%

Grain refinement of electronic solders: The potential of combining solute with nucleant particles

Shang

Belyakov

et al. 2017

Journal of Alloys and Compounds

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“…and the combination of Pb and Bi produced a low temperature eutectic that could lead to early failure [1,4,5]. Now that the industry is truly Pb-free, Bi can be used without this risk and, recently, there has been a resurgence of interest in Bi additions mainly for designing the third-generation, high-reliability electronic solders targeting applications in harsher environments [6][7][8][9][10][11][12][13]. Broadly, there are three categories of Bi-containing solders under investigation and entering service: (i) low Bi solders (typically < 2 wt% Bi) strengthened by Bi solid solution strengthening of βSn such as Sn-0.7Cu-0.05Ni-1.5Bi (wt%) [9,10]; (ii) medium Bi solders (typically 3-7 wt% Bi) strengthened by both Bi solid solution strengthening and (Bi) precipitates such as Sn-3.8Ag-0.7Cu-3Bi-1.5Sb-0.15Ni [14] and Sn-2.25Ag-0.5Cu-6Bi [7]; and (iii) solders based around the Sn-57Bi low melting eutectic for low process temperature electronics such as Sn-57Bi-1Ag, Sn-57.5Bi-0.5Sb and Sn-58Bi [15,16].…”

Section: Introductionmentioning

confidence: 99%

Precipitation and coarsening of bismuth plates in Sn–Ag–Cu–Bi and Sn–Cu–Ni–Bi solder joints

Belyakov

Xian

Zeng

et al. 2018

J Mater Sci: Mater Electron

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In recent years there has been increased interest in Bi-containing solders to improve the reliability of electronics and drive down processing temperatures. When the Bi content is more than ~ 2 wt% in SnAg -Cu-Bi and Sn-Cu-Ni-Bi solders, (Bi) phase forms by a non-equilibrium eutectic reaction and also precipitates in the solid state. Here, we study the development of bismuth plates during room temperature storage in a range of Bi-containing solders. It is shown that Bi plates precipitate with one of two (Bi)-βSn orientation relationships (ORs). During coarsening the OR with the better lattice match grows at the expense of the other, leading to a single OR. The plate coarsening kinetics scale with the cube root of holding time and are relatively rapid, with plates exceeding 1 µm in length within 1 day at room temperature. Prolonged room temperature storage of more than 1 year resulted in Bi accumulation in 5-20 µm (Bi) particles at βSn grain boundaries.

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“…Ni is increasingly added to Sn-Ag-Cu-X [2] and next-generation solder compositions [3,4]. The addition of Ni significantly affects the intermetallic reaction layers between the solder and copper [5]; a ~500 ppm Ni addition suppresses the formation of the Cu3Sn layer [6][7][8][9] and results in a finer and smaller (Cu,Ni)6Sn5 layer after reflow [8,10].…”

Section: Introductionmentioning

confidence: 99%

“…Similar to the (Cu,Ni)6Sn5 reaction layer, Ni additions significantly influence the formation of primary Cu6Sn5 in the bulk solder. Solders containing nickel usually have significantly smaller and more numerous primary Cu6Sn5 rods/particles in the bulk solder compared with Ni-free solders [14,[32][33][34][35][36][37][38]; and various papers on Ni-containing solders contain micrographs of primary Cu6Sn5 crystals with an X-shaped morphology [10,[39][40][41][42].…”

Section: Introductionmentioning

confidence: 99%

Influence of Ni on the refinement and twinning of primary Cu6Sn5 in Sn-0.7Cu-0.05Ni

et al. 2018

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The influence of Ni on the size and twinning of primary Cu6Sn5 crystals in Sn-0.7Cu-0.05Ni and Sn-xCu (x=0.7, 0.9, 1.1) (mass%) solder joints is studied using synchrotron radiography and SEM-based EBSD. It is shown that the Ni addition does not cause significant refinement of primary Cu6Sn5 if the alloy is fully melted. However, for peak temperatures ≤ 250°C relevant to industrial soldering, primary Cu6Sn5 are not completely melted in Sn-0.7Cu-0.05Ni and there are 10-100 times more numerous and smaller crystals than in Sn-0.7Cu. X-shaped Cu6Sn5 crystals with an angle of ~70° commonly formed in Sn-0.7Cu-0.05Ni/Cu joints and are shown to be penetration twins.This type of growth twinning was only found in partially melted samples, both in Sn-0.7Cu-0.05Ni/Cu joints and binary Sn-1.1Cu alloy. The frequency of twinned crystals was significantly higher in Ni-containing solders. The results are discussed in terms of the influence of Ni on the Cu6Sn5 liquidus slope and on the lattice parameters of (Cu,Ni)6Sn5.

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Influence of bismuth on the solidification of Sn-0.7Cu-0.05Ni-xBi/Cu joints

Cited by 43 publications

References 66 publications

Grain refinement of electronic solders: The potential of combining solute with nucleant particles

Grain refinement of electronic solders: The potential of combining solute with nucleant particles

Precipitation and coarsening of bismuth plates in Sn–Ag–Cu–Bi and Sn–Cu–Ni–Bi solder joints

Influence of Ni on the refinement and twinning of primary Cu6Sn5 in Sn-0.7Cu-0.05Ni

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