潮湿扩散及湿热应力对叠层封装件可靠性影响

利用MARC软件,通过模拟实验分析了潮湿扩散及湿热应力对叠层封装器件可靠性的影响,对30℃,RH 60%,192 h条件下预置吸潮到后面的无铅回流焊解吸潮过程进行了有限元仿真;对85℃,RH 85%,168 h条件下元件内不同界面的潮湿扩散进行分析,得出潮湿扩散对界面的影响规律。使用一种湿热耦合方法计算湿热合成应力并与单纯热应力进行了对比。结果表明:最大湿热应力和热应力一样总是出现在顶部芯片与隔离片相交的区域,其数值是单纯热应力数值的1.3~1.5倍。

Effects of moisture diffusion and hygrothermal stress on reliability of SCSP

Using MARC software,investigated were the effects of moisture diffusion and hygrothermal stress on reliability of SCSP by simulative experiment.A finite element model of SCSP in MARC was performed and carried out for the thermal and moisture history from the moisture preconditioning(30 ℃,RH 60%,192 h) to subsequent exposure to a lead-free reflow soldering process.Moisture diffusion of various SCSP package interface from the moisture preconditioning(85 ℃,RH 85%,168 h) was analyzed.The results show that moisture diffusion have a quite significant effect on package interface.Then,a novel method was used to calculate hygrothermal stress and compared with considering only the thermal stress conditions.The result shows the maximal hygrothermal stress and thermal stress are always appeared in the cross section of top-chip and isolate chips,the hygrothermal stress is 1.3 to 1.5 times compared with only thermal stress.