基于载荷与失效双解耦的无铅焊点温度-疲劳耦合破坏评价新方法研究

项目名称： 基于载荷与失效双解耦的无铅焊点温度-疲劳耦合破坏评价新方法研究

项目编号： No.51275007

项目类型： 面上项目

立项/批准年度： 2013

项目学科： 机械、仪表工业

项目作者： 李晓延

作者单位： 北京工业大学

项目金额： 80万元

中文摘要： 焊点加速失效的研究以往大多仅关注加速载荷与寿命的表观关系，加速中失效机理的一致性并无保证，误差和不确定性较大。本项目针对BGA封装中常用的SnAgCu/Cu焊点及热力耦合服役条件，首先将服役荷载解耦为温度分量和疲劳分量，将热力耦合失效解耦为蠕变失效分数和疲劳失效分数；据此，分别研究基于蠕变机制的温度加速载荷与蠕变失效分数的关系、研究基于疲劳机制的疲劳加速载荷与疲劳失效分数的关系；进而以载荷与相应的失效机理为基础，通过对温度-疲劳耦合加速每一循环中蠕变与疲劳失效分数的累积来表达加速寿命和加速因子。在理论上掌握焊点热力耦合加速失效的本质，在实际上为焊点寿命和可靠性评价提供新的科学方法。预计创新是：通过对载荷与失效的双解耦，确保焊点温度-疲劳耦合加速前后失效机理的一致性，有望克服以往研究对机理的模糊性;以基于机理的损伤累积所表达的加速寿命和加速因子，物理和力学意义明确，有望克服以往研究的唯象性。

中文关键词： 无铅焊点；失效机理；解耦与耦合；寿命模型；

英文摘要： Concerning the acceleration test of electronic packages, most previous studies were focused only on the relations between the applied loads and the so produced lives. Unfortunately, the failure mechanisms before and after such acceleration might be changed, the so obtained lives may not reflect the real basis due to the enclosed tolerance and uncertainties. The study on the mechanisms and evaluation of thermo-mechanical failure of SnAgCu/Cu joints, which are widely employed in BGA packages, is proposed in this proposal. The thermo-mechanical loads will be decoupled into temperature parameter and mechanical fatigue parameter, the thermo-mechanical failure will be decoupled into creep fraction and fatigue fraction. Based on the failure mechanisms, the correlation between the applied temperature load parameter and the resulted creep failure fraction will be investigated. The correlation between the applied fatigue load parameter and the resulted fatigue failure fraction will be investigated as well. Consequently, the damage of each temperature-fatigue coupling cycle could be evaluated by the above obtained creep failure fraction and fatigue failure fraction. By the accumulation of the damage produced by each cycles, the failure behavior and life of the SnAgCu/Cu joints, in the temperature-fatigue coupling cycles, c

英文关键词： lead-free solder joints；failure mechanism；decoupling and coupling；life model；