0
Research Papers

Reliability Assessment of Wafer Level Packages With Novel FeNi Under Bump Metallization

[+] Author and Article Information
Jia Xi, Xinduo Zhai, Jun Wang, Donglun Yang, Mao Ru

Department of Materials Science,
Fudan University,
Shanghai 200433, China

Fei Xiao

Department of Materials Science,
Fudan University,
Shanghai 200433, China
e-mail: feixiao@fudan.edu.cn

Li Zhang, Chi Ming Lai

Jiangyin Changdian Advanced
Packaging Co., Ltd.,
Jiangyin 214431, China

1Corresponding author.

Contributed by the Electronic and Photonic Packaging Division of ASME for publication in the JOURNAL OF ELECTRONIC PACKAGING. Manuscript received February 5, 2015; final manuscript received June 30, 2015; published online July 21, 2015. Assoc. Editor: Yi-Shao Lai.

J. Electron. Packag 137(3), 031016 (Jul 21, 2015) Paper No: EP-15-1016; doi: 10.1115/1.4030974 History: Received February 05, 2015

FeNi alloy is considered a possible substitute for Cu as under bump metallization (UBM) in wafer level package (WLP) since it forms very thin intermetallic compound (IMC) layer with Pb-free solder in the reflow process. In this paper, WLPs with FeNi and Cu UBM were fabricated and their board level reliabilities were studied comparatively. The WLP samples assembled on the printed circuit board (PCB) were subjected to temperature cycling and drop tests according to JEDEC standards. The results showed that the reliability of WLP with FeNi UBM was a little lower than that with Cu UBM. The main failure modes for both FeNi and Cu UBM samples in temperature cycling test were the crack in IMC or solder ball on PCB side. And detachments between UBM and the redistribution layer (RDL) were also observed in Cu UBM WLPs. In drop test, the crack of RDL was found in all failed FeNi UBM samples and part of Cu UBM ones, and the primary failure mode in Cu UBM samples was the crack of IMC on PCB side. In addition, the finite element analysis (FEA) was carried out to further understand the difference of the failure modes between the FeNi UBM samples and the Cu UBM samples. The high stress was observed around the UBM and the pad on PCB in the temperature cycling model. And the maximum stress appeared on the RDL in the drop simulation, which was obviously larger than that on the pad. The FEA results showed that the introduction of FeNi UBM increased the stress levels both in temperature cycling and drop tests. Thus, the FeNi alloy cannot simply replace Cu as UBM in WLP without further package structural optimization.

Copyright © 2015 by ASME
Your Session has timed out. Please sign back in to continue.

References

Liu, P. S. , Wang, J. L. , Tong, L. Y. , and Tao, Y. J. , 2014, “Advances in the Fabrication Processes and Applications of Wafer Level Packaging,” ASME J. Electron. Packag., 136(2), p. 024002. [CrossRef]
Crosbie, P. , and Lee, Y. J. , 2010, “Multiple Impact Characterization of Wafer Level Packaging (WLP),” Microelectron. Reliab., 50(4), pp. 577–582. [CrossRef]
Fan, X. J. , Varia, B. , and Han, Q. , 2010, “Design and Optimization of Thermo-Mechanical Reliability in Wafer Level Packaging,” Microelectron. Reliab., 50(4), pp. 536–546. [CrossRef]
Xu, S. , Keser, B. , Hau-Riege, C. , Bezuk, S. , and Yau, Y. W. , 2013, “A Study of Wafer Level Package Board Level Reliability,” IEEE 63rd Electronic Components and Technology Conference (ECTC), Las Vegas, NV, May 28–31, pp. 1204–1209.
An, T. , Qin, F. , and Xia, G. F. , 2013, “Analytical Solutions and a Numerical Approach for Diffusion-Induced Stresses in Intermetallic Compound Layers of Solder Joints,” ASME J. Electron. Packag., 136(1), p. 011001. [CrossRef]
Ladani, L. , and Abdelhadi, O. , 2014, “Structural Size Effect on Mechanical Behavior of Intermetallic Material in Solder Joints: Experimental Investigation,” ASME J. Electron. Packag., 137(1), p. 014501. [CrossRef]
Zeng, K. , and Tu, K. N. , 2002, “Six Cases of Reliability Study of Pb-Free Solder Joints in Electronic Packaging Technology,” Mater. Sci. Eng., R, 38(2), pp. 55–105. [CrossRef]
He, M. , Lau, W. H. , and Qi, G. J. , 2003, “Intermetallic Compound Formation Between Sn-3.5Ag Solder and Ni-Based Metallization During Liquid State Reaction,” Thin Solid Films, 462, pp. 376–383.
Alam, M. O. , Chan, Y. C. , and Tu, K. N. , 2003, “Effect of Reaction Time and P Content on Mechanical Strength of the Interface Formed Between Eutectic Sn-Ag Solder and Au/Electroless Ni(P)/Cu Bond Pad,” J. Appl. Phys., 94(6), pp. 4108–4115. [CrossRef]
Alam, M. O. , Chan, Y. C. , and Hung, K. C. , 2002, “Reliability Study of the Electroless Ni-P Layer Against Solder Alloy,” Microelectron. Reliab., 42(7), pp. 1065–1073. [CrossRef]
Chonan, Y. , Komiyama, T. , Onuki, J. , Urao, R. , Kimura, T. , and Nagano, T. , 2002, “Influence of Phosphorus Concentration in Electroless Plated Ni-P Alloy Film on Interfacial Structures and Strength Between Sn-Ag-(-Cu) Solder and Plated Ni-P Alloy Film,” Mater. Trans., 43(8), pp. 1840–1846. [CrossRef]
Hwang, C. W. , Suganuma, K. , Lee, J. G. , and Mori, H. , 2003, “Interface Microstructure Between Fe-42Ni Alloy and Pure Sn,” J. Mater. Res., 18(5), pp. 1202–1210. [CrossRef]
Dariavach, N. , Callahan, P. , and Liang, J. , 2006, “Intermetallic Growth Kinetics for Sn-Ag, Sn-Cu, and Sn-Ag-Cu Lead-Free Solders on Cu, Ni, and Fe-42Ni Substrates,” J. Electron. Mater., 35(7), pp. 1581–1592. [CrossRef]
Guo, J. J. , Zhang, L. , and Xian, A. P. , 2007, “Solderability of Electrodeposited Fe-Ni Alloys With Eutectic SnAgCu Solder,” J. Mater. Sci. Technol., 23(6), pp. 811–816.
Zhu, Q. S. , Guo, J. J. , and Wang, Z. G. , 2008, “Shear of Sn-3.8Ag-0.7Cu Solder Balls on Electrodeposited FeNi Layer,” International Conference on Electronic Packaging Technology and High Density Packaging (ICEPT-HDP 2008), Shanghai, July 28–31, pp. 848–851.
Zhang, H. , Wu, D. , Zhang, L. , Duan, Z. Z. , Lai, C. M. , and Liu, Z. Q. , 2012, “Wafer Level Electrodeposition of Fe-Ni Novel UBM Films,” Acta Metall. Sin., 48(10), pp. 1273–1280 (in Chinese). [CrossRef]
JEDEC, 2005, “Temperature Cycling,” JEDEC Solid State Technology Association, Arlington, VA.
IPC, 2002, “Performance Test Methods and Qualification Requirements for Surface Mount Solder Attachments,” IPC–Association Connecting Electronics Industries, Bannockburn, IL.
JEDEC, 2003, “Board Level Drop Test Method of Components for Handheld Electronic Products,” JEDEC Solid State Technology Association, Arlington, VA.
Zhang, H. , Zhu, Q. S. , Liu, Z. Q. , Zhang, L. , Guo, H. Y. , and Lai, C. M. , 2014, “Effect of Fe Content on the Interfacial Reliability of SnAgCu/FeeNi Solder Joints,” J. Mater. Sci. Technol., 30(9), pp. 928–933. [CrossRef]

Figures

Grahic Jump Location
Fig. 1

Schematic processes of WLP with FeNi UBM/Cu UBM

Grahic Jump Location
Fig. 2

Test board with samples assembled

Grahic Jump Location
Fig. 3

Interfacial morphology of solder joints with different UBM after reflow

Grahic Jump Location
Fig. 4

Weibull distribution of WLPs in temperature cycling tests

Grahic Jump Location
Fig. 5

Failure modes of FeNi UBM samples in temperature cycling tests: (a) crack in IMC and (b) crack in solder ball

Grahic Jump Location
Fig. 6

Crack in solder from the edge of UBM in Fe-64Ni WLPs

Grahic Jump Location
Fig. 7

Detachment between UBM and RDL in Cu UBM samples

Grahic Jump Location
Fig. 8

Weibull distribution of WLPs in drop tests

Grahic Jump Location
Fig. 9

Failure modes in drop tests: (a) break of RDL and (b) crack in IMC

Grahic Jump Location
Fig. 10

Finite element mesh: (a) temperature cycling model and (b) drop model

Grahic Jump Location
Fig. 11

Equivalent stress distribution of FeNi UBM sample in temperature cycling simulation (unit in Pa)

Grahic Jump Location
Fig. 12

Equivalent stress distribution of Cu UBM sample in temperature cycling simulation (unit in Pa)

Grahic Jump Location
Fig. 13

Equivalent stress distribution of FeNi UBM sample in the drop test (unit in kPa)

Grahic Jump Location
Fig. 14

Equivalent stress distribution of Cu UBM sample in the drop test (unit in kPa)

Grahic Jump Location
Fig. 15

Stress–time curves at maximum stress position on the RDL and the PCB pad

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