热循环对Sn58Bi(纳米Ti)/Cu焊点界面与性能影响

Effect of thermal cycling on interface and properties of Sn58Bi(nano Ti)/Cu solder joints

摘要:

为了改善Sn-58Bi低温钎料的性能,通过在Sn-58Bi低温钎料中添加质量分数为0.1%的纳米Ti颗粒制备了Sn-58Bi-0.1Ti纳米增强复合钎料。在本文中,研究了纳米Ti颗粒的添加对-55～125 _^oC热循环过程中Sn-58Bi/Cu焊点的界面金属间化合物(IMC)生长行为的影响。研究结果表明：回流焊后,在Sn-58Bi/Cu焊点和Sn-58Bi-0.1Ti/Cu焊点的界面处都形成一层扇贝状的Cu₆Sn₅ IMC层。在热循环300次后,在Cu₆Sn₅/Cu界面处形成了一层Cu₃Sn IMC。Sn-58Bi/Cu焊点和Sn-58Bi-0.1Ti/Cu焊点的IMC层厚度均和热循环时间的平方根呈线性关系。但是,Sn-58Bi-0.1Ti/Cu焊点的IMC层厚度明显低于Sn-58B/Cu焊点,这表明纳米Ti颗粒的添加能有效抑制热循环过程中界面IMC的过度生长。另外计算了这两种焊点的IMC层扩散系数,结果发现Sn-58Bi-0.1Ti/Cu焊点的IMC层扩散系数(整体IMC、Cu₆Sn₅和Cu₃Sn IMC)明显比Sn-58Bi/Cu焊点小,这在一定程度上解释了Ti纳米颗粒对界面IMC层的抑制作用。

Abstract:

In order to improve the performance of Sn-58Bi lead-free solder, the Sn-58Bi-0.1Ti nanometer reinforced composite solder was prepared by incorporating 0.1% Ti nanoparticles into the Sn-58Bi solder. In this paper, the effect of adding Ti nanoparticles on the growth behavior of intermetallic compounds (IMC) in Sn-58Bi/Cu solder joints during thermal cycling was studied. The results showed that a scallop-like Cu₆Sn₅ IMC layer was formed at Sn-58Bi /Cu and Sn-58Bi-0.1Ti/Cu interface after reflow soldering. After 300 thermal cycles, a layer of Cu₃Sn IMC was formed at the Cu₆Sn₅/Cu interface. The thickness of IMC layer of Sn-58Bi/Cu solder joint and Sn-58Bi-0.1Ti/Cu solder joint is proportional to the square of thermal cycling time. However, the IMC thickness of Sn-58Bi-0.1Ti/Cu solder joint is significantly lower than that of Sn-58B/Cu solder joint, which indicated that the addition of Ti nanoparticles can effectively inhibit the excessive growth of interfacial IMC during the thermal cycle process. In addition, the IMC layer diffusion coefficients of these two solder joints were calculated, and it was found that the diffusion coefficients of IMC layer in Sn-58Bi-0.1Ti/Cu solder joint (overall IMC, Cu₆Sn₅ and Cu₃Sn IMC) were smaller than that of Sn-58Bi/Cu solder joint, which explained the inhibitory effect of Ti nanoparticles on the interface IMC layer to some extent.