Fabrication and Characterization of Flexible Ultrathin Chip Package Using Photosensitive Polyimide
Fabrication and Characterization of Flexible Ultrathin Chip Package Using Photosensitive Polyimide
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使用光敏聚酰亚胺的柔性超薄芯片封装的制造和表征
DOI：
10.1109/tcpmt.2012.2188402
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
J. Vanfleteren
中科院分区：
文献类型：
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作者：
Liang Wang;T. Sterken;M. Cauwe;D. Cuypers;J. Vanfleteren
为满足电子产品体积更小、重量更轻的需求，装配减薄模具已成为一种普遍做法。实现这一目标的一种方法是将变薄的芯片嵌入两个介电薄膜中，从而形成柔性超薄芯片封装（UTCP）。本文介绍了一种利用光敏聚酰亚胺（PSPI）标准紫外光刻形成微孔的UTCP工艺流程。这种微孔形成方法被证明比激光钻孔技术更可靠，比干蚀刻工艺更简单。由于使用的PSPI是自吸的，因此引入了一层薄薄的氯化钾作为释放层。最终，减薄芯片的聚酰亚胺封装可以从载体基板上释放出来，成为总厚度约为50 μm的柔性芯片封装。雏菊链试验模封装在自旋涂覆聚酰亚胺薄膜内。通过电气菊花链和接触电阻测量证明了出色的芯片到封装互连。在雏菊链试验车上进行了弯曲试验和热循环试验。观察到utcp所需的灵活性和可靠性。
Assembly of thinned die has become common practice to meet the demand for smaller and lighter electronic products. One way to achieve this goal is to embed the thinned die into two dielectric films, which results in a flexible ultrathin chip package (UTCP). This paper describes a new UTCP process flow with microvia formation by standard UV lithography through photosensitive polyimide (PSPI). Such microvia-formation method proved to be more reliable than laser drilling techniques and simpler than a dry etching process. Since the used PSPI is self-priming, a thin layer of potassium chloride was introduced as a release layer. In the end, the polyimide encapsulation of the thinned die can be released from the carrier substrate and becomes a flexible chip package with a total thickness of around 50 μm. Daisy-chain test dies were encapsulated inside spin-coated polyimide films. Excellent chip-to-package interconnection was demonstrated by electrical daisy chain and contact resistance measurements. Bending tests and thermal cycling tests were also performed on the daisy-chain test vehicles. Desired flexibility and reliability of UTCPs was observed.