Typical die shift is beyond several tens micrometers or more, which is a serious problem on advanced fan-out wafer-level packaging (FOWLP), to give inevitable misalignment errors in the subsequent photolithography processes for fine-pitch redistributed wiring layer (RDL) formation. In particular, this problem is expected to grow all the more serious in chiplets and tiny dies less than 1 mm in a side. In this work, the use of an anchoring layer is proposed to fix these dies/chiplets on a double-side laminate thermo-release tape and drastically reduce the die shift. In addition, an on-nail photoplethysmogram (PPG) sensor module as a part of flexible hybrid electronics (FHE) is integrated with $\mu $ LED ( $270\,\,\mu \text{m}\,\,\times 270\,\,\mu \text{m}$ ) based on a die-first FOWLP methodology using a biocompatible polydimethylsiloxane (PDMS) mold resin for real-time monitoring pulse wave and percutaneous oxygen saturation (SpO ₂ ). The repeated bendability of fan-out Au wirings formed on the PDMS and the current–voltage ( $I$ – $V$ ) behavior of the $\mu $ LED before and after die embedment in the PDMS is characterized.

中文翻译：

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大幅降低模移和 μ基于模切优先扇出晶圆级封装的LED集成，用于柔性混合电子

典型的管芯偏移超过几十微米或更多，这在先进的扇出晶圆级封装（FOWLP）上是一个严重的问题，在后续的用于精细间距重新分布布线层（RDL）形成的光刻工艺中会产生不可避免的失准误差。特别是，预计该问题在小芯片和侧面小于1毫米的小芯片上会更加严重。在这项工作中，建议使用锚固层将这些管芯/小芯片固定在双面层压热释放带上，并大幅度减少管芯偏移。此外，作为柔性混合电子设备（FHE）的一部分的指甲上光电容积描记（PPG）传感器模块与 $ \亩$ 发光二极管 （ $ 270 \，\，\ mu \ text {m} \，\，\ times 270 \，\，\ mu \ text {m} $ ）基于模头优先FOWLP方法，该方法使用生物相容性聚二甲基硅氧烷（PDMS）模制树脂实时监测脉搏波和经皮氧饱和度（SpO ₂ ）。PDMS上形成的扇形金导线的重复弯曲性和电流-电压（ $ I $ – $ V $ ）的行为 $ \亩$ 将芯片嵌入PDMS之前和之后的LED进行了表征。