Study Of Bondable Laser Release Material Using 355nm Energy To Facilitate RDL-First And Die-First Fan-Out Wafer-Level Packaging (FOWLP)

Finding the right bondable laser release material that eliminates die attach material from the process flow.


A thorough evaluation on selecting a bondable laser release material for redistribution layer (RDL)-first and die-first fan-out wafer-level packaging (FOWLP) is presented in this article. Four laser release materials were identified based on their absorption coefficient at 355 nm. In addition, all four of these materials possess thermal stability above 350 °C and pull-off adhesion on a Ti/Cu layer greater than 8 psi, further illustrating their compatibility in FOWLP. To further evaluate these materials, focus ion beam (FIB) inspection was used to examine the profile of a single-pulse laser ablation region, ensuring free penetration of 355-nm laser energy. With a designated die bonding test vehicle, die shift less than 1.5 μm and rotation less than 0.02° before and after molding was achieved with the material bondable at temperatures lower than 200 °C. Furthermore, this same material required a laser energy of less than 3 W for laser release. A bondable laser release material that eliminates the requirement for a die attach material from the traditional process flow facilitates the development of cost-effective FOWLP.

Published in: IEEE Transactions on Components, Packaging and Manufacturing Technology ( Volume: 12, Issue: 4, April 2022)

Click here to view the article page on IEEE.

Authors are:

Chia-Hsin Lee and Kuan-Neng Chen
International College of Semiconductor Technology, National Yang Ming Chiao Tung University, Hsinchu, Taiwan

Baron Huang, Jennifer See, and Luke Prenger
Brewer Science, Inc., Rolla, MO, USA

Yu-Min Lin, Wei-Lan Chiu, and Ou-Hsiang Lee
Electronic and Optoelectronic System Research Laboratories, Industrial Technology Research Institute (ITRI), Hsinchu, Taiwan

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