无铅焊点及其内部金属间化合物的力学性能研究

Mechanical Properties of Lead-Free Solder Joints and Its Inner Intermetallic Compounds

摘要:

采用纳米压痕技术对无铅焊点 (Sn3.0Ag0.5Cu、Sn0.7Cu和Sn3.5Ag) 及其内部界面金属间化合物 (intermetallic compound, IMC)的力学性能进行测试。根据实际工业工艺流程制备无铅焊点试样；利用接触刚度连续测量(CSM)技术对焊点及内部IMC层进行测试，得到IMC层及无铅焊点的弹性模量、硬度等力学性能参数，并根据载荷-位移曲线的保载阶段确定蠕变应力指数。结果表明，Sn0.7Cu的IMC层的弹性模量和蠕变应力指数为无铅焊点的2.03和6.73倍；对无铅焊点的可靠性评估中，将IMC层的影响考虑进去使得结果更为合理

Abstract:

The mechanical properties of lead-free solder (Sn3.0Ag0.5Cu, Sn0.7Cu and Sn3.5Ag) joints and its inner intermetallic compounds (IMC) were measured by nanoindentation. The samples were prepared according to actual reflow soldering condition and service. Using the continuous stiffness measurement (CSM) technique, the values of hardness and elastic modulus for lead-free solder joints and IMC were measured. The creep stress exponents were obtained according to nanoindentation. The result indicates that the elastic modulus and creep stress exponents of IMC of Sn0.7Cu are 2.03 and 6.73 times of lead-free solders. It is reasonable to consider the influence of the IMC layer when evaluating the lead-free solder joints reliability