Alloying modification of Sn–Ag–Cu solders by manganese and titanium

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

“…Thus, the additions are suitable for studying the effect of nucleant particles at near-constant Q. with Ti, Co, and Pt additions. This strongly reduced ΔTn with these 7 additions is consistent with past work [38,40,72] and indicates that the addition levels were suitable. By comparing Figure 10(A) and (B) it can be seen that there is no simple correlation between undercooling and grain size.…”

“…Further work is required to confirm the heterogeneous nucleation mechanisms with Zn, Ti, and Mn additions. It may be that Ti2Sn3 and MnSn2 are heterogeneous nucleants for βSn [72] although this has not been proved yet and the fact that Mn additions did not result in significant grain refinement ( Figure 9 and Figure 10) but did contain numerous MnSn2 particles ( Figure 11) suggests that a detailed study on the influence of Mn is required. Similarly, a detailed study is required to identify the heterogeneous nucleants introduced by Zn additions.…”

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

“…In all cases, the nucleation undercooling of βSn was relatively high and variable and the addition of 0.05wt%Ni or 1.5-14wt%Bi to Sn-0.7Cu did not have any clear influence on the undercooling. We note that this is in contrast to various other additions, such as Zn [53,54], Al [53], Mn [55], Ti [55], Pt or Pd [56] or Co [54,57] which strongly reduce the βSn nucleation undercooling in Sn-Cu, Sn-Ag and Sn-Ag-Cu solders. As can be seen in Figure 8, the joints with up to 5wt%Bi solidified with near-columnar growth of βSn from the Cu6Sn5 layer.…”

Advances in Pb-free Solder Microstructure Control and Interconnect Design

“…[12][13][14][15][16][17][18][19][20] Anderson and co-workers have examined a wide range of additions to SAC alloys; Al (0.05 wt.%), Zn ( ‡0.21 wt.%), and Mn ( ‡0.1 wt.%) were each found to reduce b-Sn undercoolings to 2-4°C, and to reduce, or eliminate, the formation of Ag 3 Sn proeutectic blades. The early studies were not able to identify the cause of the observed benefits from the micro-alloying additions, but did state that the specific micro-alloying additions were chosen because of their substitutional solubility in Cu and with the goal of enhanced nucleation of primary Cu 6 Sn 5 from which the b-Sn could then nucleate.…”

“…This lack of microstructure control has motivated significant research on the effects of minor alloy additions to SAC or other binary Sn-based alloys on Sn nucleation over a number of years. [12][13][14][15][16][17][18][19][20] In contrast to circuit board assembly solders in which many high-Sn alloys are available commercially, Au-based eutectics (Au-Sn, Au-Si, Au-Ge) are the dominant Pb-free alloys used for high-temperature soldering applications, but Fig. 1 Two differing projections of the liquidus surface of the Sn-Ag-Cu ternary system.…”