遥感器印刷电路板组件用微小焊点可靠性理论及长寿命设计

Electronics devices are developing in the direction of high integration density and small size. The mechanical properties and the microstructure evolutions have significant differences between the microscale solder joints and the bulk solder joints. The size effect of microscale solder joints has brought the reliability of the aerospace products into sharp focus. There was no mature theory to design the reliability of micro solder joints right now. To solve the reliability challenges of both lead and lead-free microscale solder joints for bonding BGA devices, LCC devices and 0402 resistance and electric capacities, this project aims at evaluation of the reliability of typical tin based solder joints of Sn63Pb37 and SnAg3.0Cu0.5. Considering the complex vacuum environment in the space, it is planning to reveal the interactions between high current density, Joule heating effect, and high thermal stress in microscale solder joints, and harsh environment temperature as well as mechanical load. We are going to clarify the mechanism of intermetallic compounds growth adjacent to interface, element accumulation or segregation, and crystal whiskers of the microscale solder joints as well as the dynamic laws. Consequently, we could reveal the essence of the size effects on the microstructure evolution of the microscale solder joints. A multi-scale cyclic constitutive model coupled with damage as well as an interface failure model will be proposed. Then a life prediction method for the microscale solder joints and life extension methods are planning to be proposed, considering the interactions among electricity, heat, and mechanics, to improve its long lifetime design theory. The results and conclusions have theoretical and practical significance for the improvement of service reliability and design capability of China's satellite remote sensor.

电子器件朝着高集成和尺寸小微化方向发展，其中微米级焊点的力学性能和组织演化与体焊点存在显著差异，使得微焊点的尺寸效应对宇航产品可靠性的影响备受关注。目前国内外尚无成熟的微焊点可靠性设计理论。针对卫星遥感器中典型有铅和无铅混搭的BGA器件、LCC器件和0402阻容器件的可靠性问题，以Sn63Pb37和SnAg3.0Cu0.5为研究对象，结合宇航空间的复杂真空环境，重点揭示小尺寸焊点导致的高电流密度、焦耳热效应、高热失配应力问题与严苛环境温度、机械载荷的耦合作用规律，探究微焊点界面合金层生长、元素富集/偏析和晶须的成因及动力学规律，澄清尺寸效应导致焊点微组织演化差异的本质，建立考虑损伤累积的多尺度循环本构模型与界面失效模型，提出电-热-力交互作用下微焊点互连器件的疲劳寿命预测模型及延寿方法，完善其长寿命设计理论。研究成果对我国卫星遥感器的服役可靠性保障与设计能力提升具有重要理论和工程实践意义。

电子器件朝着高集成和尺寸小微化方向发展，其中微米级焊点的力学性能和组织演化与体焊点存在显著差异，使得微焊点的尺寸效应对宇航产品可靠性的影响备受关注。目前国内外尚无成熟的微焊点可靠性设计理论。针对卫星遥感器中典型器件的可靠性问题，以SnAg3.0Cu0.5为研究对象，结合宇航空间的复杂真空环境，重点揭示小尺寸焊点导致的高电流密度、焦耳热效应、高热失配应力问题与严苛环境温度、机械载荷的耦合作用规律，探究微焊点界面合金层生长及动力学规律，澄清尺寸效应导致焊点微组织演化差异的本质，建立考虑损伤累积的多尺度循环本构模型与界面失效模型，提出电-热-力交互作用下微焊点互连器件的疲劳寿命预测模型及延寿方法，完善其长寿命设计理论。主要创新点：（1）系统研究了电-热耦合作用下微焊点的时效演变及缺陷演化规律，澄清了焊点回流与固态时效老化及其金属间化合物的生长与演化机制，建立了不同厚度镀层界面金属间化合层厚与老化时长的物理模型；（2）在随动硬化律中引入温度相关项与率相关项来考虑温度-机械载荷的交互作用，并将背应力与损伤内变量相关联，建立了描述SAC305材料的耦合损伤循环粘塑性本构模型，能很好预测多场耦合作用下材料的热-机应力应变响应，并对全寿命下材料的棘轮变形准确预测；（3）研究发现随温度升高，SAC305焊点的率相关性降低。将塑性滑移变形与温度和应变率相关联，建立了温度相关与率相关的晶体塑性有限元模型，准确描述了不同温度与加载率下SAC305焊点的应力应变响应；（4）提出了一种综合考虑电场、温度场、应力场和原子浓度场耦合作用的仿真方法，澄清了互连引线结构和互连焊点结构的原子浓度分布规律，确定了原子浓度最小值处出现空洞的判据，准确预测了互连结构中空洞出现的位置。研究成果对我国卫星遥感器的服役可靠性保障与设计能力提升具有重要理论和工程实践意义。