摘要
利用纳米压痕技术分别采用阶梯加载和一次加载方式,研究了一种SnAgCu无铅钎料BGA(ball grid array)微焊点体钎料的蠕变行为。结果表明:在载荷同为60 mN、保载时间为300 s条件下,阶梯加载条件下的蠕变位移明显小于一次加载条件下的蠕变位移,而蠕变硬度却是一次加载下的1.87倍,蠕变硬度显著提高。在阶梯加载方式下三个阶段的压痕蠕变不断降低,蠕变硬度不断升高。拟合计算出阶梯加载和一次加载条件下的蠕变应力指数n,阶梯加载条件下微焊点的应力指数n比一次加载条件下提高1.31倍。在阶梯加载条件下产生的应变硬化,提高了微焊点的抗蠕变性能。
Creep behavior of the ball grid array（BGA）of lead-free solder joints of Sn-0.7 Ag-0.5 Cu-3.5 Bi-0.05 Ni（SACBN）was investigated via nanoindentation by step loading-unloading and single loading-unloading respectively.The results show that：for the two different test modes with the same load 60 mN and holding time 300 s,the creep displacement of solder joints by step loading-unloading is significantly less than that by single loading-unloading.However,the creep hardness for the former case is 1.87 times of that of the later one.The indentation creep decreased at three stages for the case of step loading-unloading,however the creep hardness increased.The creep exponent n was obtained by fitting calculation and found that the n value for the step loading-unloading is 1.31 times of that for single loading-unloading.The creep resistance performance of micro solder joints was improved by strain hardening during the process of step loading-unloading.
作者
孔祥霞
孙凤莲
杨淼森
KONG Xiangxia;SUN Fenglian;YANG Miaosen(School of Material Science and Engineering, Harbin University of Science and Technology, Harbin 150040, China)
出处
《材料研究学报》
EI
CAS
CSCD
北大核心
2018年第3期184-190,共7页
Chinese Journal of Materials Research
基金
国家自然科学基金资助项目51174069~~
关键词
金属材料
纳米压痕
微焊点
抗蠕变性能
阶梯加载
应力指数
metallic materials, nanoindentation, micro solder joints, creep resistance, step loading-unloading, stress index
