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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: 10075U. D. C. NO: 20111355A Dissertation for the degree of M. EngineeringStudy on Dynamic Mechanical Properties of Low Silver Lead-Free Solder Candidate:Li
2、NaSupervisor:A.P. Niu XiaoyanAcademic Degree Applied for:Master of EngineeringSpecialty:Solid MechanicsUniversity:Hebei UniversityDate of Oral Examination:May, 2014摘 要摘 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度下使用
3、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软化效应较低
4、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AbstractAbstractIt is inevitable to
5、 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 solde a
6、ccordingly. 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 rese
7、arch 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 the
8、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 Sn0.3A
9、g0.7Cu 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 di
10、fferent 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 mode
11、l 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; Compare
12、d 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 re
13、sistance to drop.Key words low silver lead-free solder SHPB Johnson-Cook model the finite element analysis 目 录目 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112.2.1 冲击响应的影响因素112.2.2 冲击动力学的响应的分析方法112.3 跌落冲击132.3.1 概述1
14、32.3.2 BGA板级跌落冲击实验装置142.3.3 跌落理论18第3章 低银无铅焊料动态力学性能的实验研究203.1 引言203.2 力学实验203.2.1 试件制备及加工203.2.2 静态实验装置及原理203.2.3 动态实验装置及原理233.3 实验结果及分析263.3.1 应变率对材料力学性能的影响263.3.2 温度对材料力学性能的影响283.3.3 温度与应变率共同作用对材料力学性能的影响303.4 本构关系的确定303.5 本章小结32第4章 VFBGA 焊点在跌落冲击下的有限元分析344.1 引言344.2.1 有限元思想344.2.2 ANSYS/LS-DYNA简介374.3 有限元模拟394.3.1 有限元模型的建立394.3.2 材料参数404.3.3 载荷和边界条件424.4 有限元结果分析434.4.1 室温下焊点的有限元分析444.4.2 温度对焊点的影响454.4.3 与高银焊料的比较474.5本章小结48第5章 结论与与展望505.1 结论505.2 下一步工作展望51参考文献52致 谢57I第1章 绪 论第1章 绪 论 1.1 电子封装概述电子
