Modeling spatial strain gradient effects in thermo-mechanical fatigue of copper microstructures

Pucha, Raghuram V.; Ramakrishna, Gnyaneshwar; Mahalingam, Saketh; Sitaraman, Suresh K.

doi:10.1016/j.ijfatigue.2004.01.008

Cited by 16 publications

(4 citation statements)

References 21 publications

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“…The Engelmaier (1978, 1987) fatigue model which came out of the IPC copper foil ductility round‐robin study can be used to predict trace line thermal fatigue life. It has been verified and compared to the experimental results in different papers (Iannuzzelli, 1991; Pucha et al , 2004). Equation (2) shows the model which is applied for low‐to‐high cycle fatigue: Equation 2 where Δ ε is the total strain range, N f is the number of mean cycles‐to‐failure, D f is the fatigue ductility coefficient, E is Young's modulus, and S u is the ultimate tensile strength.…”

Section: Fundamental Theorymentioning

confidence: 64%

Reliability analysis of a novel fan‐out type WLP

Yew

Tsai²,

Hu³

et al. 2009

Soldering &Amp; Surface Mount Technology

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PurposeThe wafer level package (WLP) is a cost‐effective solution for electronic packaging and has been increasingly applied in recent years. The purpose of this paper is to propose a newly developed packaging technology, based on the concepts of the WLP, the panel base package (PBP) technology, in order to further obtain the capability of signal fan‐out for fine‐pitched integrated circuits (ICc).Design/methodology/approachIn the PBP, the filler material is selected to fill the trench around the chip and provide a smooth surface for the redistribution lines. Therefore, the solder bumps could be located on both the filler and the chip surface and the pitch of the chip side is fanned‐out. The design concept and the manufacturing process of the PBP would first be described in this study. The three‐dimensional finite element model is established based on the real testing sample and the thermo‐mechanical behavior of the PBP is simulated.FindingsIt is found that the solder joint reliability of the PBP can be highly improved because of the applied stress buffer layer. However, the accumulated stress/strain from the coefficient of thermal expansion mismatch may transfer to the metal lines in package. In order to enhance the robustness of the redistribution lines, the bypassed type interconnect is suggested. Moreover, the trace/pad connecting junction and the conductive via which have smooth outline are preferred to avoid stress concentration effects.Originality/valueIn this paper, a low‐cost and short time‐to‐market packaging technology is proposed which is especially suitable for high density IC devices. The PBP technology has the ability to meet the requirements of major reliability testing conditions and it will have a high potential for application in the near future.

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Section: Fundamental Theorymentioning

confidence: 64%

Reliability analysis of a novel fan‐out type WLP

Yew

Tsai²,

Hu³

et al. 2009

Soldering &Amp; Surface Mount Technology

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“…The facts of the strength increasing with decreasing thickness of thin beams in micro-bending test are found by Stolken and Evans (1998), Shrotriya et al (2003) and Haque and Saif (2003). Thermo-mechanical fatigue has relation with the spatial strain gradient effects too (Pucha et al, 2004).…”

Section: Introductionmentioning

confidence: 88%

Small scale, grain size and substrate effects in nano-indentation experiment of film–substrate systems

Chen

Liu

Wang

2007

International Journal of Solids and Structures

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The mechanical properties of film-substrate systems have been investigated through nano-indentation experiments in our former paper (Chen, S.H., Liu, L., Wang, T.C., 2005. Investigation of the mechanical properties of thin films by nano-indentation, considering the effects of thickness and different coating-substrate combinations. Surf. Coat. Technol., 191,[25][26][27][28][29][30][31][32], in which Al-Glass with three different film thicknesses are adopted and it is found that the relation between the hardness H and normalized indentation depth h/t, where t denotes the film thickness, exhibits three different regimes: (i) the hardness decreases obviously with increasing indentation depth; (ii) then, the hardness keeps an almost constant value in the range of 0.1-0.7 of the normalized indentation depth h/t; (iii) after that, the hardness increases with increasing indentation depth. In this paper, the indentation image is further investigated and finite element method is used to analyze the nano-indentation phenomena with both classical plasticity and strain gradient plasticity theories. Not only the case with an ideal sharp indenter tip but also that with a round one is considered in both theories. Finally, we find that the classical plasticity theory can not predict the experimental results, even considering the indenter tip curvature. However, the strain gradient plasticity theory can describe the experimental data very well not only at a shallow indentation depth but also at a deep depth. Strain gradient and substrate effects are proved to coexist in film-substrate nano-indentation experiments.

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“…It is significant to note that the length scale when material scale effects are predominant in copper is about 2.8 [32]. When the plastic spatial strain gradients are considered in the hardening behavior of copper, it is seen that the strain in microvia could reduce and, therefore, the predicted fatigue life would go up by a factor of two, especially for microvias with the plating thickness of less than 5 [33]. 2) Optical Function Reliability: Electrical interconnections at high speeds are limited by several factors, including frequency dependent signal attenuation, crosstalk, high power consumption, jitter, and skew [34].…”

Section: ) Digital Function Reliability: Upfront Process Optimizatiomentioning

confidence: 99%

System-Level Reliability Assessment of Mixed-Signal Convergent Microsystems

Pucha

Hegde

Damani

et al. 2004

IEEE Trans. Adv. Packag.

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The next-generation convergent microsystems, based on system-on-package (SOP) technology, require up-front system-level design-for-reliability approaches and appropriate reliability assessment methodologies to guarantee the reliability of digital, optical, and radio frequency (RF) functions, as well as their interfaces. Systems approach to reliability requires the development of: i) physics-based reliability models for various failure mechanisms associated with digital, optical, and RF Functions, and their interfaces in the system; ii) design optimization models for the selection of suitable materials and processing conditions for reliability, as well as functionality; and iii) system-level reliability models understanding the component and functional interaction. This paper presents the reliability assessment of digital, optical, and RF functions in SOP-based microsystems. Upfront physics-based design-for-reliability models for various functional failure mechanisms are presented to evaluate various design options and material selection even before the prototypes are made. Advanced modeling methodologies and algorithms to accommodate material length scale effects due to enhanced system integration and miniaturization are presented. System-level mixed-signal reliability is discussed thorough system-level reliability metrics relating component-level failure mechanisms to system-level signal integrity, as well as statistical aspects.

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Modeling spatial strain gradient effects in thermo-mechanical fatigue of copper microstructures

Cited by 16 publications

References 21 publications

Reliability analysis of a novel fan‐out type WLP

Reliability analysis of a novel fan‐out type WLP

Small scale, grain size and substrate effects in nano-indentation experiment of film–substrate systems

System-Level Reliability Assessment of Mixed-Signal Convergent Microsystems

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