化学镀Ni-P在纯锡凸点的应用及界面研究

采用化学镀Ni-P作UBM阻挡层,利用电镀的方法制备了面阵列和周边排布的无铅纯锡凸点,凸点高度为85±2μm,一致性良好。研究了不同回流温度下纯锡焊球的剪切强度、断裂模式和与Ni-P层反应生成的金属间化合物。结果表明,纯锡凸点回流时与Ni-P生成针状Ni3Sn4,凸点剪切强度达到92MPa以上。剪切断裂为韧性断裂,随着回流温度提高及回流时间延长,Ni3Sn4相由针状向块状转变,Ni-P层与Ni3Sn4层间生成层状Ni3P相,粗化的Ni3Sn4相受压应力向焊球内部脱落。

Study on Electroless Ni-P Application in Tin Bump and Their Interfacial Reaction

Electroless plating Ni-P was used as under bump metallization barrier layer. The array and peripheral pure tin solder was electroplated. The uniformity of solders with (85±2) μm in height was good after reflow. The shear strength of solder and its failure and the morphology and constitute of intermetallic between solder and UBM layers mode were studied. The results show that the needle-like Ni3Sn4 intermetallic is formed during reflow process, which result in 92 MPa shear strength of solders. The shear failure of solder is always ductile fracture. With increasing the reflow temperature and time, needle-like Ni3Sn4 intermetallic begin ripen and fine Ni3P intermetallic is formed between electroless Ni-P layer and Ni3Sn4 layer and spall-off into the solder due to compressive stress.