Large Ag₃Sn plates in solder joints can affect the reliability of electronics, however, the factors affecting their nucleation and morphology are not well understood. Here, the faceted solidification of Ag₃Sn was studied as a function of melt undercooling, revealing transitions from single crystal {001} plates to cyclic twinned plates and then to highly branched structures created by twin mediated branching. Real-time X-ray imaging proved that Ag₃Sn cyclic twins come from a common point, indicating they initiate in the process of nucleation or in the very early stages of growth in the undercooled melt. Soldering to copper substrates significantly catalysed Ag₃Sn nucleation. This is shown to be due to constitutional supercooling generated by Ag solute rejection into the liquid ahead of the Cu₆Sn₅ reaction layer, with additional contributions from geometrical catalysis in the grooves between Cu₆Sn₅ scallops and heterogeneous nucleation of Ag₃Sn on Cu₆Sn₅. The relative ease of Ag₃Sn nucleation on the Cu₆Sn₅ reaction layer is responsible for the large plates often reported in electronic solder joints.

焊点中的大 Ag ₃ Sn 板会影响电子产品的可靠性，但是，影响其成核和形态的因素尚不清楚。_{在这里，研究了 Ag 3} Sn的刻面凝固作为熔体过冷的函数，揭示了从单晶 {001} 板到环状孪晶板再到由孪晶介导的支化产生的高度支化结构的转变。实时 X 射线成像证明 Ag ₃ Sn 环状孪晶来自一个公共点，表明它们在成核过程中或在过冷熔体中生长的非常早期阶段开始。焊接到铜基板显着催化 Ag ₃Sn成核。这表明是由于 Ag 溶质排斥到 Cu ₆ Sn _{5反应层之前的液体中产生的结构过冷，以及 Cu 6} Sn ₅扇贝之间的凹槽中的几何催化和 Ag ₃ Sn 在表面上的异相成核的额外贡献。铜₆锡₅。Cu ₆ Sn _{5反应层上Ag 3} Sn相对容易成核是电子焊点中经常报告的大板的原因。