再布线圆片级封装板级跌落可靠性研究

Study on Board Level Drop Reliability of Wafer Level Packaging with Redistribution Structure

再布线圆片级封装通过对芯片焊区的重新构造以及无源元件的集成可以进一步提升封装密度、降低封装成本。再布线圆片级封装器件广泛应用于便携式设备中,在实际的装载、运输和使用过程中抗冲击可靠性受到高度重视。按照JEDEC标准对再布线圆片级封装样品进行了板级跌落试验,首先分析了器件在基板上不同组装点位的可靠性差异;然后依次探讨了不同节距和焊球尺寸、再布线结构对器件可靠性的影响;最后,对失效样品进行剖面制样,采用数字光学显微进行形貌表征。在此基础上,结合有限元分析对再布线结构和铜凸块结构的圆片级封装的可靠性和失效机理进行深入地阐释。

Abstract： Wafer level packaging （WLP） with redistribution layers （RDL） could realize high density packaging and cost reduction by relocating the pads over the active area layer and integrating passive components. Wafer level packages are widely applied in portable devices, and during loading, transportation and practical using, the wafer shock resistance have attracted much attention. Board level drop test was conducted on WLP with RDL according to the JEDEC standard, firstly, The reliability of the components assembled at different positions on PCB was analyzed. Then the influences of the RDL structure, pitch size and solder ball size on the reliability of RDL structure WLP devices were studied. Finally, the failed samples were analyzed by the cross-section observation using the digital optical microscopy. Based on the three dimensional finite element model and failure analysis results, the failure mechanism of the RDL and copper pillar structured WLPs caused by drop shock were explained.