## WLCSP热循环对无铅焊点性能影响研究

Thermal cycling on properties of lead-free solder
Abstract
With the rapid development of electronic packaging technology, WLCSP as an advanced packaging technology emerged.Through the establishment 1/4 model of WLCSP package for the study, we use Garofalo-Arrheninus model construct SnAgCu solder constitutive equations then apply ANSYS software to simulate, and under the thermal cycling conditions, study the solder joint reliability sexual and fatigue life, while analyze and compare four joints, research the height, the diameter of solder joints and how the pads diameter affect on the solder joint fatigue life.Final conclusions are as follows: the maximum stress is in the surface of the solder joints corner. Based on creep strain energy density solder joint fatigue life equation is more accurate. Solder joint height, diameter and pads diameter affect solder joint fatigue life .
Keywords: WLCSP Package、finite element analysis、Creep strain、Creep strain energy density、Fatigue Life 源￥自%六:维;论-文'网=www.lwfree.cn

Abstract    II

1.1集成电路封装的发展    1
1.2 WLCSP(晶圆级芯片封装技术)    3
1.3无铅钎料    4
1.4热疲劳对焊点可靠性的影响    7
1.5本文研究的主要内容和意义    7
1.6本章小结    7

2.1有限元方法    8
2.2 有限元法的基本思想    8
2.3有限元法的发展与应用    8
2.4 ANSYS软件介绍    10
2.5 ANSYS有限元分析主要流程    10
2.6 Garofalo-Arrhenius 稳态本构方程    11
2.7 本章小结    12

3.1 WLCSP封装模型    13
3.2 几何模型简化    13
3.3 选取材料和建立几何模型    13
3.4 单元选取与材料参数    17
3.5加载边界条件    17
3.6 本章小结    18

4.1 蠕变程序的编写与输入    19
4.2 焊点在热循环条件下的应力应变分析    19
4.3 焊点疲劳寿命预测    21
4.4 本章小结    23

5.1焊点高度对焊点疲劳寿命的影响    24
5.2无铅焊点直径对无铅焊点疲劳寿命的影响    24
5.3焊盘直径对无铅焊点疲劳寿命的影响    24
5.4 本章小结    26 源￥自%六:维;论-文'网=www.lwfree.cn

1.1集成电路封装的发展

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