In this paper, CPI (chip-package interaction) reliability of WLP (wafer level package) was investigated. PBO (Polybenzoxazole)-based RDL (redistribution layer) structure was the primary focus. Firstly, the stress distribution for PBO structures was studied by simulation. Secondly, two types of the chip with different PBO structures completed the accelerating experiments. Based on our investigation, the results of CPI reliability tests are coincident with the simulation data. It can be applied to the early prediction for the risk level of CPI reliability. Additionally, failure mechanisms were figured out for different PBO structures. Design A has the potential risk to suffer corrosion damage owing to exposed SR (seal ring) and CAS (crack stop). Design B has a four times failure rate in THT (Temperature and Humidity Test), which related to hotspots around SR. These results suggest that protecting SR and relieving hotspots effect will effectively enhance CPI reliability performance of WLP.

中文翻译：

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基于PBO的不同RDL结构对晶圆级封装芯片-封装交互可靠性的影响

在本文中，研究了WLP（晶圆级封装）的CPI（芯片-封装交互）可靠性。基于 PBO（聚苯并恶唑）的 RDL（再分布层）结构是主要关注点。首先，通过模拟研究了PBO结构的应力分布。其次，两种不同PBO结构的芯片完成了加速实验。根据我们的调查，CPI 可靠性测试的结果与仿真数据一致。可用于CPI可靠性风险水平的早期预测。此外，还找出了不同 PBO 结构的失效机制。由于暴露的 SR（密封环）和 CAS（止裂装置），设计 A 具有遭受腐蚀损坏的潜在风险。设计 B 在 THT（温度和湿度测试）中的失败率是四倍，这与SR周围的热点有关。这些结果表明，保护SR和缓解热点效应将有效提高WLP的CPI可靠性性能。