银浆沾污引起的芯片损伤机理分析

Mechanism Analysis of Chip Damages Caused by Contamination from Silver Paste

对两只塑封器件开封后进行内部目检,发现一只样品存在金属层损伤缺陷,另一只样品芯片表面有大量多余物。利用扫描电镜和能谱仪对缺陷部位和多余物进一步进行形貌观察和元素成分分析,结果表明金属层损伤部位有导电银浆残留物,损伤形貌明显为压应力造成,而芯片表面的大量多余物也含有导电银浆残留物,呈扁平状,局部区域有钝化层被压碎的形貌特征。根据微电子塑封封装工艺流程进行分析,认为芯片损伤机理为:粘接工艺控制不良导致导电银浆在芯片上残留,环氧塑封料固化过程中收缩产生的压应力通过银浆残留物将芯片金属层和钝化层压碎。

Internal visual examination was performed on two plastic packaging devices after decapping.It was found that the metal layer in one chip was damaged,while a lot of foreign material was appeared on the other chip.Morphology observation and element composition analysis were performed on the damage parts and foreign materials by using scanning electron microscope and energy dispersive spectroscopy.The results showed that conductive silver paste was remained on the damaged metal layer which was caused by pressure stress obviously,while the foreign material on chip surface contained flat residual of conductive sliver paste and some regions of passivation layer on chip surface were crushed.Mechanisms of chip damage were analyzed by considering plastic packaging process,and it was concluded that bad adhesive bonding operation was the reason for conductive silver paste remained on the chip,which crushed metal layer and passivation layer by pressure stress from shrinking in the process of curing of epoxy molding compound.