The morphology evolution of Cu₆Sn₅ grains in (001)Cu/Sn/Cu and (011)Cu/Sn/Cu micro solder joints reflowing with and without a temperature gradient was studied. In the as-soldered state, regular and perpendicular prism-type Cu₆Sn₅ grains formed on (001)Cu substrate, while a mixture of stubby prism-type and scallop-type Cu₆Sn₅ grains formed on (011)Cu substrate. The prism-type morphology gradually transferred into scallop-type after isothermally reflowed at 270 °C for 10 min. However, with a temperature gradient, the initial perpendicular small prismatic Cu₆Sn₅ grains on (001)Cu substrate and mixed-type Cu₆Sn₅ grains on (011)Cu continued to grow into large prism-type. All the prism-type Cu₆Sn₅ grains grew along same direction after long time reflow under temperature gradient due to the merging of adjacent Cu₆Sn₅ grain pair.

研究了（001）Cu / Sn / Cu和（011）Cu / Sn / Cu微焊点中有无温度梯度回流时Cu ₆ Sn ₅晶粒的形貌演变。在焊接状态下，在（001）Cu衬底上形成规则和垂直的棱柱形Cu ₆ Sn ₅晶粒，而在（011）Cu衬底上形成粗短棱柱形和扇贝形Cu ₆ Sn ₅晶粒的混合物。在270°C等温回流10分钟后，棱柱形形态逐渐转变为扇贝形。但是，在温度梯度的作用下，（001）Cu衬底上的初始垂直小棱形Cu ₆ Sn ₅晶粒和混合型Cu ₆（011）Cu上的Sn ₅晶粒继续长成大棱柱形。由于相邻的Cu ₆ Sn ₅晶粒对的合并，所有的棱柱型Cu ₆ Sn ₅晶粒在长时间回流后在温度梯度下沿相同方向生长。