Influence of bismuth on the solidification of Sn-0.7Cu-0.05Ni-xBi/Cu joints
Influence of bismuth on the solidification of Sn-0.7Cu-0.05Ni-xBi/Cu joints
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DOI：
10.1016/j.jallcom.2016.12.404
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发表时间：
2017-04
影响因子：
6.2
通讯作者：
S. Belyakov;J. Xian;K. Sweatman;T. Nishimura;T. Akaiwa;C. Gourlay
中科院分区：
文献类型：
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作者：
S. Belyakov;J. Xian;K. Sweatman;T. Nishimura;T. Akaiwa;C. Gourlay
由于铋添加剂的焊点机械性能的改善是持续的兴趣。本文研究了0-14 wt% Bi对Cu基Sn-0.7 wt%Cu-0.05 wt%Ni-xBi钎料球组织形成的影响。结果表明，Bi的加入降低了（Cu，Ni）6Sn 5合金中Ni的含量，增大了（Cu，Ni）6Sn 5合金中初生（Cu，Ni）6Sn 5合金棒的尺寸，减小了Cu 6Sn 5合金反应层的厚度，但当Bi的含量达到~ 5wt%时，这些影响是微弱的，且当Bi的加入量≤ 5wt%时，对Ni的正面影响并不显著.较高的Bi添加量（≥ 8wt% Bi）导致锡生长织构从具有纤维织构的柱状晶<110>向具有亚晶的单一晶粒转变。Bi的加入增加了非平衡凝固范围，并在含Bi ≥ 2wt%的接头中引起非平衡三元共晶反应。需要小于2wt%的Bi含量以防止在固化期间形成（Bi）相。
The improvement of solder joint mechanical performance due to bismuth additions is of ongoing interest. This paper investigates the influence of 0–14 wt% Bi on microstructure formation in Sn-0.7 wt%Cu-0.05 wt%Ni-xBi solder balls on Cu substrates. It is shown that Bi additions reduce the Ni content of (Cu,Ni)6Sn5, increase the size of primary (Cu,Ni)6Sn5rods and reduce the thickness of the Cu6Sn5reaction layer, although these effects are subtle until the Bi content reaches ∼5 wt%Bi and Bi additions of ≤5 wt% did not significantly affect the positive effects of Ni. Higher Bi additions (≥8 wt% Bi) caused a transition of the tin growth texture from columnar grains with a <110> fibre texture towards a single grain with subgrains. Bi additions increased the non-equilibrium freezing range and caused a nonequilibrium ternary eutectic reaction in joints containing ≥2 wt% Bi. Bi contents less than 2 wt% are required to prevent (Bi) phase formation during solidification.