0
research-article

Improvement of Thermo-Mechanical Reliability of Wafer Level Chip Scale Packaging

[+] Author and Article Information
Lei Shi

State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University, Shanghai 200433, China
shi.lei@tfme.com

Lin Chen

State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University, Shanghai 200433, China
linchen@fudan.edu.cn

David Wei Zhang

State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University, Shanghai 200433, China
dwzhang@fudan.edu.cn

Evan Liu

Tongfu Microelectronics Co.,LTD, Nantong, Jiangsu 226006, China
evan.liu@tfme.com

Qiang Liu

Tongfu Microelectronics Co.,LTD, Nantong, Jiangsu 226006, ChinaSchool of Microelectronics, Tianjin University, Tianjin 300072, China
qiangliu@tju.edu.cn

Ching-I Chen

Mechanical Engineering, Chung Hua University, Hsinchu, Taiwan 30012
meching@chu.edu.tw

1Corresponding author.

ASME doi:10.1115/1.4038245 History: Received March 23, 2017; Revised October 06, 2017

Abstract

Due to low cost and good electrical performance, wafer level chip scale packaging (WLCSP) has gained more attentions in both industry and academia. However, because the coefficient of thermal expansion (CTE) mismatch between silicon and organic printed circuit board (PCB), WLCSP technology still faces reliability challenges, such as the solder joint fragile life issue. In this paper, a new WLCSP design (WLCSP-PN) is proposed, based on the structure of WLCSP with Cu posts (WLCSP-P), to release the stress on the solder joints. In the new design, there is a space between the Cu post and the polymer which permits NiSn coating on the post sidewall. The overcoating enhances the solder-post interface where cracks were initiated and enlarges the IMC joint area to enhance the adhesion strength. Design of experiment (DOE) with the Taguchi method is adopted to obtain the sensitivity information of design parameters of the new design by the three-dimensional finite element model (FEM), leading to the optimized configuration. The finite element analysis results demonstrate that compared to WLCSP-P the proposed WLCSP-PN reduces the package displacement, equivalent stress and plastic strain energy density, and thus improves the fatigue life of solder joints.

Copyright (c) 2017 by ASME
Your Session has timed out. Please sign back in to continue.

References

Figures

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In