有铅和无铅倒装焊点研究

Solder Joint Research of Flip Chip with Lead and Lead-free Solders

首先对有铅和无铅倒装焊点的剪切强度进行了对比,并对其焊点的断口形貌进行了观察,然后对焊点界面的组织成分进行了分析。试验结果表明,97.5Sn2.5Ag焊点界面主要形成物是Ni3Sn4金属间化合物,90Pb10Sn焊点界面主要形成物是Ni3Sn2和Ni3Sn4,97.5Sn2.5Ag芯片的剪切强度大于90Pb10Sn的剪切强度,断裂位置位于基板焊盘与Mo的结合面或芯片UBM与粘附层的结合面,90Pb10Sn断裂位置位于焊料内部,表明97.5Sn2.5Ag焊料的抗剪切强度更高,而90Pb10Sn焊料的塑性和韧性更好。

Joint shear strength of flip chip with leaded and lead-free solder was compared, and the fracture morphologies of solder joints were observed, and then the structure and components of joints interface were analyzed. The results showed that, Ni3Sn4 was mainly formed at the interface of 97.5Sn2.5Ag solder joints, while Ni3Sn2 and Ni3Sn4 at the interface of 90Pb10 Sn solder joints. The chip shear strength of 97.5Sn2.5Ag joints was greater with the fractures located at the interface of substrate pads and Mo or the interface of UBM and adhesive layer, and 90Pb10 Sn fractures located inside the solder, which indicated higher shear strength of 97.5Sn2.5Ag joints and better plasticity and tenacity of 90Pb10 Sn joints.