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1、密 级： 学校代码：10075分类号： 学 号：20111355工 学 硕 士 学 位 论 文低银无铅焊料的动态力学性能研究学位申请人：李娜指导教师：牛晓燕 副教授学位类别：工学硕士学科专业：固体力学授予单位：河北大学答辩日期：二一四年五月Classified Index: CODE: 10075 U. D. C. NO: 20111355A Dissertation for the degree of M. EngineeringStudy on Dynamic Mechanical Properties of Low Silver Lead-Free Solder Candidate: L
2、i NaSupervisor: A.P. Niu XiaoyanAcademic Degree Applied for: Master of EngineeringSpecialty: Solid MechanicsUniversity: Hebei UniversityDate of Oral Examination: May, 2014摘 要便携式电子产品在运输与使用过程中经常会发生跌落与撞击等问题，要求焊点具备优异的抗跌落性能。另外，电子元器件在服役过程中会放出大量的热量，导致焊点温度升高，我国部分地区冬季的温度历史上最低达为-50左右，也会影响焊点的实际温度，对电子产品在较低或较高的温
3、度下使用都会影响焊点的力学性能，从而影响其寿命。目前对低温下焊点的力学性能研究还很少。随着人类环保意识的增强及电子行业对成本的控制，低银无铅焊料逐渐取代了高银无铅焊料。也为焊点的可靠性提出了新的课题。基于以上问题，本文对低银无铅焊料的力学性能以及焊点的可靠性进行了系统性的研究，主要工作和结果如下：（1）在不同工况下，采用电子万能材料试验机和分离式霍普金森压杆装置（SHPB）对低银无铅焊料Sn0.3Ag0.7Cu 分别进行准静态和动态试验，研究发现，在不同的温度范围内，应变率与温度对低银焊料Sn0.3Ag0.7Cu 的塑性变形的影响是不同的，在中高温区（40100） ，材料的应变率硬化效应和温度
4、软化效应较低温区（-450）明显减弱；基于以上实验数据和Johnson-Cook 模型拟合得到低温和中高温下Sn0.3Ag0.7Cu 的动态本构关系。（2）对板级 VFBGA 封装的跌落情况进行有限元分析，结果表明，对于低银无铅焊料 Sn0.3Ag0.7Cu，低温下焊点上最大应力的分布主要分布在焊点的界面处，与中高温不同；与高银焊料相比，低银焊点的测试板一侧应力要大于封装体一侧，与高银焊点正好相反，且最大应力大大低于高银焊料，也说明低银焊料的抗跌落性能明显优于高银焊料。关键词 低银无铅焊料 霍普金森压杆 Johnson-Cook 模型 有限元分析AbstractIt is inevitable
5、 to cause the portable electronic products drop or impact in the process of transportation or application，so we expect the solder joints own excellent resistance to drop .In addition, the electronic components will release a lot of heat in the process of service, and lead to high temperature of sold
6、e accordingly. The lowest temperature of our country in the history is around for - 50 , which will affect the mechanical properties of solder joints in the use of electronic products under low or high temperature, thus the life of electronic products to use is affected. Currently, there is little r
7、esearch about the mechanical properties of solder joints under low temperature. Along with the improve of human awareness of environmental protection and cost control of electronic industry, low-silver lead-free solders products were gradually replaced high-silver solder products, also put forward t
8、he new subject for the solder joint reliability.To solve the above problems, in this paper the mechanical properties of low silver lead-free solder and solder joint reliability of systematic were studied. The main work and results list as follows: 1）The mechanical properties of low silver solder Sn0
9、.3Ag0.7Cu were characterized by using an electronic universal material testing system and Split Hopkinson Pressure Bar (SHPB) under different conditions. The results show that the strain rate hardening and temperature softening effects on the plastic deformation of low silver solder Sn0.3Ag0.7Cu are
10、 different among experiment temperature ranges. In high temperatures (40100), the strain rate hardening effect and temperature softening effect were weaker than low temperature (-450). The dynamic constitutive relationship was determined through these experiments based on Johnson-Cook model. 2）The m
11、odel of VFBGA packaging in board-level drop condition was established by the finite element method. The results show that, as for low silver lead-free solder Sn0.3Ag0.7Cu, the distribution of the maximum stress on the joints was observed in the interface of the solder joints at low temperature; Comp
12、ared with high silver solder , the stress around test plate side silver solder is greater than that around the side of the package, while high silver solder just the opposite ;And the maximum stress of low silver lead-free solder is much lower than that of the high silver solder , which shows better resistance to drop.Key words low silver lead-free solder SHPB Johnson-Cook model the finite element analysis 目 录第 1 章 绪 论.11.1 电子封装概述.11.1.1 电子封装的分类.21.1.2 电子封装的历史.31.2 电子封装的可靠性.41.3 无铅焊点的可靠性及研究现状.61.4 本论文的主要研究内容.8第 2 章 冲击动力学.102.1 冲击动力学概述.102.2 冲击载荷的响应.
