湿热环境下吸潮对QFN器件可靠性的影响研究

Effects of Moisture on the Reliability of QFN Device in Hygro-Thermal Environment

由吸潮引起的微电子塑封器件失效已经越来越多地引起人们的关注。选用QFN器件作为研究对象,首先进行QFN器件在高温高湿环境下吸潮17 h、50 h、96 h试验;然后利用有限元软件分析和模拟潮湿在QFN器件中的扩散行为,并建立湿气预处理阶段应力计算模型;最后,通过试验与仿真相结合,分析潮湿对封装可靠性的影响。研究表明:微电子塑封器件的潮湿扩散速度与位置有着重要的关系;在高温高湿环境下,微电子器件吸潮产生的湿热应力在模塑封装材料(EMC)、硅芯片(DIE)和芯下材料(DA)的交界处最大;QFN器件在高温高湿环境下吸潮产生的裂纹主要出现在硅芯片与DA材料交界面的边界。

QFN devices were exposed in hygro-thermal environment for 17 h, 50 h and 96 h, and moisture diffusion into QFN devices was analyzed and simulated, to build a wet-stress calculation model. Based on test and simulation results, influence of moisture on reliability of device packages was studied. It has been shown that velocity of moisture diffusion depended on location of plastic packaged devices, and the maximum hygro-thermal stress was on the interface of epoxy molding compound （EMC）, DIE and die-attach （DA） materials. Cracks on QFN device resulting from moisture under hygro-thermal environment were observed mostly on the interface between Si chip and die attach material.