Development of process modeling methodology for flip chip on flex interconnections with non-conductive adhesives

Zhang, Xiaowu; Wong, E.H.; Rajoo, R.; Iyer, M.K.; Caers, J.F.J.M.; Zhao, Xiujuan

doi:10.1016/j.microrel.2004.07.112

Cited by 12 publications

(7 citation statements)

References 8 publications

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“…It is shown that the pressure is very stable (no relaxation) during the static TH (85 C/85%RH). As we know, the contact resistance only depends on the bump pressure [4]. Thus, simulation predicts that the contact resistance is also very stabe during static TH (85 C/85%RH) over 1000 h. The reason for no stress relaxation may be due to the NCA modulus has reached infinite within a few hours (Fig.…”

Section: Finite Element Modelingmentioning

confidence: 89%

“…In recent years, extensive studies [1]- [21] have been performed on adhesive interconnections in various areas such as process induced residual stress [1]- [4], characterization of contact resistances [4]- [6], and development and characterization of adhesive materials [7]- [19]. Although this technology is already widely used [1]- [19], the degradation mechanisms are not completely documented, and aging kinetics are poorly understood [20], [21]. As a result, proper reliability assessment for any new application is impossible.…”

Section: Integrated Process-aging Modeling Methodology I Introductionmentioning

confidence: 99%

“…The cure shrinkage or cure force of the NCA during the curing process is also obtained in Table I. The detailed description of cure shrinkage characterization is shown in literature [4].…”

Section: Materials Characterization Of the Ncamentioning

confidence: 99%

“…Here, is 17.71 MPa and is 417.9 MPa. Stress in the viscoelastic NCA can be related to strain at any time by the convolution integral (4) where is stress, is total strain including thermal strain, is time, and is reduced time. For thermorheologically simple materials, temperature effect is introduced through a reduced time concept.…”

Section: Materials Characterization Of the Ncamentioning

confidence: 99%

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Integrated Process-Aging Modeling Methodology for Flip Chip on Flex Interconnections With Nonconductive Adhesives

Zhang

Wong

Rajoo

et al. 2008

IEEE Trans. Adv. Packag.

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This paper presents a comprehensive methodology to model the static temperature-humidity (TH) aging test (85 C/85%RH over 1000 h) of flip chip on flex interconnections with nonconductive adhesives (NCAs). NCAs, being a special form of conductive adhesives, are chosen, as they allow bringing the pitch further down. The methodology combines experimental techniques for material characterization, finite element modeling (FEM), and model validation. A NCA has been characterized using several techniques. The thermomechanical properties and the moisture absorption properties were obtained for the NCA. A temperature dependent viscoelastic constitutive model was also obtained for the NCA. The viscoelastic model was defined by the Prony series expansion. The shift factor was approximated by the Williams-Landel-Ferry (WLF) equation. Finite element modeling has been performed to analyze the flip chip interconnects on flex with the NCA under process condition and reliability aging conditions. The viscoelastic constitutive relation has been used to model the NCA in aging modeling. An integrated process-aging modeling methodology has been developed to combine the thermo-mechanical stress and hygro-mechanical stress, followed by stress relaxation analysis. To verify the finite element models, static TH aging tests (85 C/85%RH) were also performed. The contact resistance was monitored with high measuring resolution during the accelerated test. The simulation results are in good agreement with the experimental results. The approach developed in this paper can be used to provide guidelines with respect to adhesive material properties, assembly process parameters to achieve good reliability performance.Index Terms-Finite element modeling (FEM), flex substrate, flip chip, moisture absorption properties, nonconductive adhesives, static temperature-humidity (TH) aging test, viscoelasticity.

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Section: Finite Element Modelingmentioning

confidence: 89%

Section: Integrated Process-aging Modeling Methodology I Introductionmentioning

confidence: 99%

“…The cure shrinkage or cure force of the NCA during the curing process is also obtained in Table I. The detailed description of cure shrinkage characterization is shown in literature [4].…”

Section: Materials Characterization Of the Ncamentioning

confidence: 99%

Section: Materials Characterization Of the Ncamentioning

confidence: 99%

See 2 more Smart Citations

Integrated Process-Aging Modeling Methodology for Flip Chip on Flex Interconnections With Nonconductive Adhesives

Zhang

Wong

Rajoo

et al. 2008

IEEE Trans. Adv. Packag.

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“…Lu and Wong [9] measured the shrinkage of conductive epoxy adhesives with a thermo-mechanical analyser (TMA) and found volume changes [11] used a force-based method to measure the shrinkage of non-conductive adhesives for electronics packaging. This method suspends an adhesive droplet between two glass rods.…”

Section: Adhesive Shrinkagementioning

confidence: 99%

Adhesive Joints for Low- and High-Temperature Use: An Overview

Marques

Silva

Banea

et al. 2014

The Journal of Adhesion

157

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This work presents a review of several investigations on the topic of adhesive bonding at high and low temperatures. Durability and strength at extreme temperatures have always been a major limitation of adhesives that, given their polymeric nature, exhibit substantial degradation at temperatures where other structural materials (such as metals for example) have minute changes in mechanical properties. However, due to the inherent advantages of bonding, there is a large and continued effort aiming to improve the temperature resistance of adhesive joints, and this effort has been spread among the various topics that are discussed in this review. These topics include adhesive shrinkage and thermal expansion, adhesive properties, joint geometry optimization, and design techniques, among others. The findings of these research efforts have all found use in practical applications, helping to solve complex problems in a variety of high-tech industries where there is a constant need to produce light and strong components that can withstand large temperature gradients. Therefore, the final sections of this work include a discussion on two specific application areas that demonstrate the strict demands that extreme temperature use imposes on adhesive joints and the methods used to improve their performance.

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