Board level solder joint reliability analysis of a fine pitch Cu post type wafer level package (WLP)

Zhang, Xiaowu; Kripesh, V.; Chai, Tai Chong; Tan, Teck Chun; Pinjala, D.

doi:10.1016/j.microrel.2007.05.009

Cited by 16 publications

(5 citation statements)

References 29 publications

(32 reference statements)

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“…Meanwhile, the shape of solder bump is also important, the domed solder bump has a better reliability than the flat and dished solder bump (Chung et al, 2009;Park et al, 2012). The pitch of copper post bump should be shrunk due to the need of miniaturization, and the proper pitch can also improve reliability effectively (Bao et al, 2014;Zhang et al, 2008). The reliability of WLP is also affected by other structures, such as underfill, Al pad, low k layer (Chen and Lin, 2010;Alberti et al, 2015;Zhang et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Thermal-mechanical reliability analysis of WLP with fine-pitch copper post bumps

Sun

Gao

Zhao

2020

SSMT

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Purpose This study aims to investigate the several parameters in wafer-level packaging (WLP) to find the most critical factor impacting the thermal fatigue life, such as the height of copper post, the height of solder bump, the thickness of chip. The FEA results indicate the height of solder bumps is the most important factor in the whole structure. Design/methodology/approach The copper post bumps with 65 µm pitch are proposed to investigate the thermal-mechanical performance of WLP. The thermal cycle simulation is used to evaluate the reliability of WLP by using finite element analysis (FEA). Taguchi method is adopted to obtain the sensitivity of parameters of three-dimension finite element model, for an optimized configuration. Findings It can be found that the optimal design has increased thermal fatigue life by 147% compared with the original one. Originality/value It is concluded that the finite element simulation results show outstanding thermal-mechanical performances of the proposed 65 µm pitch copper post bumps of WLP, including low plastic strain, high thermal fatigue life, which are desired for mobile device.

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Section: Introductionmentioning

confidence: 99%

Thermal-mechanical reliability analysis of WLP with fine-pitch copper post bumps

Sun

Gao

Zhao

2020

SSMT

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“…In MEMS devices as well as electronics devices, wafer level vacuum packaging is one of the most important issues to reduce fabrication cost and to realize easy encapsulation [1][2][3] . For the wafer level packaging, low temperature bonding has an important role to reduce residual stress mainly due to the mismatch of the coefficient of thermal expansion (CTE) between substrates [4][5][6] .…”

Section: Introductionmentioning

confidence: 99%

Evaluations of low temperature bonding using Au sub-micron particles for wafer level MEMS packaging

Ito

Ogashiwa

Kanehira

et al. 2011

2011 International Symposium on Advanced Packaging Materials (APM)

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This paper describes wafer level vacuum packaging with sub-micron Au particles for MEMS (micro electro mechanical systems) applications. Low temperature bonding is indispensable for relevant MEMS packaging, and use of sub-micron Au particles are suitable for hermetic seal bonding. For the fabrication of hermetically sealed wafer level packaging, a base silicon wafer and a cap glass wafer were bonded at around 200ºC. Before bonding, the surface of seal rings was observed with a laser microscope to investigate the effect of surface roughness for hermeticity. After bonding, bonded wafers were dipped in the hydrofluoroether for 30 min. As a result, surface flatness of Au particles contributed to achieve hermetic sealing. Double seal rings structures were also useful to realize hermetic sealing.

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“…Finite Element Method (FEM) has been widely used in the mechanical analysis and prediction of fatigue life for Ball Grid Array Package (BGAP) due to its advantage in the field of steady elasticplastic or transient visco-plastic stress/strain calculation for solder ball joints. Currently, main research hot points are centering around creating two-dimensional [1][2][3] , three-dimensional [4][5][6][7][8][9][10][11][12] and slice models [13][14][15] for Finite Element Analysis (FEA), or developing analytical model for theoretic analysis [15][16] . Some deficiencies were presented for both two-dimensional and slice model if multiple chips are deployed in one package: the models have difficulties in reflecting all factors.…”

Section: Introductionmentioning

confidence: 99%

Simplified Three-Dimensional Thermomechanical Applications of Ball Grid Array Package

Jia

Zhang

2011

AMR

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Three dimensional finite element models were created utilizing APDL (ANSYS Parametric Design Language) for typical multi-chip BGAP (Ball Grid Array Packages) with different sizes to analyze the structure stress and strain when loading steady thermal loads upon them. Subsequently an improved modeling approach including equivalent beam and critical solder ball joint for simplification was studied and introduced. The Darveaux method based on plastic deformation energy accumulation for predicting fatigue life of solder ball joint under thermal cyclic loading was applied to the improved model for calculation, and effects of main design parameters upon fatigue life were studied accordingly. The numerical results reflected the stress distribution and varying traits of the package, compare of results between improved model and detailed model indicates that the simplified modeling method is quite effective and available for different types of analysis. Methods and results of this paper are of certain reference value for the design and optimization for similar kind of packages.

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Board level solder joint reliability analysis of a fine pitch Cu post type wafer level package (WLP)

Cited by 16 publications

References 29 publications

Thermal-mechanical reliability analysis of WLP with fine-pitch copper post bumps

Thermal-mechanical reliability analysis of WLP with fine-pitch copper post bumps

Evaluations of low temperature bonding using Au sub-micron particles for wafer level MEMS packaging

Simplified Three-Dimensional Thermomechanical Applications of Ball Grid Array Package

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