摘要
采用Abaqus软件模拟了CPU和DDR双层芯片堆叠封装组件在85℃/RH85%湿热环境下分别吸湿5,17,55和168 h的相对湿气扩散分布和吸湿168 h后回流焊过程中湿应力、热应力和湿热应力分布,并通过吸湿和回流焊实验分析了该组件在湿热环境下的失效机理。模拟结果表明,在湿热环境下,分别位于基板和CPU、CPU和DDR之间的粘结层1和2不易吸湿,造成粘结层的相对湿度比塑封材料低得多,但粘结层1的相对湿度比粘结层2要高。吸湿168 h后,在回流焊载荷下湿应力主要集中在芯片DDR远离中心的长边上,而最大湿热应力和热应力一样位于底层芯片CPU的底角处,其数值是单纯热应力的1.3倍。实验结果表明,界面裂纹及分层集中在底层CPU芯片的边角处和芯片、粘结层和塑封材料的交界处,与模拟结果相一致。
The relative humidity distribution of CPU and DDR stacked dices package module under the 85 ℃ /RH85% hygrothermal environment for 5,17,55 and 168 h and hygro-mechanical stress,thermo-mechanical stress,and hygro-thermo-mechanical stress distribution for 168 h during reflow process were simulated by Abaqus. Moisture absorption and reflow soldering experiments were performed to investigate the failure mechanism of this module in the hygrothermal environment. The results show that the adhesive layer 1 and 2 sandwiched between the substrate and CPU,CPU and DDR respectively have much lower moisture absorption rate in absorbing moisture under the hygrothermal environment,so the relative humidity of the adhesive layers are much lower than that of epoxy molding compounds. However,the relative humidity of the adhesive layer 1 is much higher than that of the adhesive layer 2. After absorbing moisture 168 h,hygro-mechanical stress mainly appears at long side away from the center of the DDR chip during reflow process. However,the maximum hygro-thermo-mechanical stress and thermo-mechanical stress locate at the die corner of the bottom CPU,and the hygro-thermo-mechanical stress is 1. 3times of pure thermo-mechanical stress. It is observed that the interface cracks and delamination appear at the interfaces of the die corner of the bottom CPU chips,adhesive layers and epoxy molding compounds after moisture absorption and reflowing experiment,and the experiment results are agreed with simulation results.
出处
《半导体技术》
CAS
CSCD
北大核心
2014年第7期539-544,共6页
Semiconductor Technology
基金
中国博士后科学基金资助项目(2014M552193)
广东省科技计划资助项目(2012B020313004)
中央高校基本科研业务费专项资金资助项目(2014ZB0032)
广东高校优秀青年创新人才培养计划资助项目(LYM11077)
关键词
芯片堆叠封装
湿气扩散
湿热应力
界面分层
有限元分析(FEA)
stacked dices package
moisture diffusion
hygro-thermo-mechanical stress
interface delamination
finite element analysis（FEA）
