Constriction Resistance of Thin Film Contacts

Timsit, R. S.

doi:10.1109/tcapt.2010.2052051

Cited by 43 publications

(46 citation statements)

References 6 publications

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“…However, we used a partially idealized model which excludes the surface roughness and the results show some uncertainties due to numerical errors. Research in [19], on the influence of the thin film on the contact resistance, was based on one contact spot and is also limited by some restriction in the film thickness and the contact area sizes. None of the above contact resistance models can be used to analyze the evolution of the resistance obtained in this paper.…”

Section: A Contact Resistance Versus Compressionmentioning

confidence: 99%

Evaluation of Anisotropic Conductive Films Based on Vertical Fibers for Post-CMOS Wafer-Level Packaging

Diop¹,

Radji

Hamoui

et al. 2013

IEEE Trans. Compon., Packag. Manufact. Technol.

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Abstract-In this paper, we investigate the mechanical and electrical properties of an anisotropic conductive film (ACF) on the basis of high-density vertical fibers for a wafer-level packaging (WLP) application. As part of the WaferBoard, a reconfigurable circuit platform for rapid system prototyping, ACF is used as an intermediate film providing compliant and vertical electrical connection between chip contacts and a top surface of an active wafer-size large-area IC. The chosen ACF is first tested by an indentation technique. The results show that the elastic-plastic deformation mode as well as the Young's modulus and the hardness depend on the indentation depth. Second, the efficiency of the electrical contact is tested using a uniaxial compression on a stack comprising a dummy ball grid array (BGA) board, an ACF, and a thin Al film. For three bump diameters, as the compression increases, the resistance values decrease before reaching low and stable values. Despite the BGA solder bumps exhibit plastic deformation after compression, no damage is found on the ACF film. These results show that vertical fiber ACFs can be used for nonpermanent bonding in a WLP application.

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Section: A Contact Resistance Versus Compressionmentioning

confidence: 99%

Evaluation of Anisotropic Conductive Films Based on Vertical Fibers for Post-CMOS Wafer-Level Packaging

Diop¹,

Radji

Hamoui

et al. 2013

IEEE Trans. Compon., Packag. Manufact. Technol.

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“…The DC resistance of geometries similar to Fig. 1 was previously studied analytically by Zhang et al 21 From this work, the expected theoretical spreading resistance may be derived as R spread,theo =R C 2πwσ [20] where R C is a function of the relative conductivities of the electrode and electrolyte as well as the geometric parameters. The analytical expression for R C is unwieldy, but in the limit of R ode / R yte → ∞ it may be simplified 21 as…”

Section: 232943mentioning

confidence: 88%

A Precise, Reduced-Parameter Model of Thin Film Electrolyte Impedance

McNealy

Jiang

Hertz

2015

J. Electrochem. Soc.

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The extreme shape factors inherent in characterizing thin film electrolytes can present a challenge to quantitative interpretation of impedance spectra. Here, the impedance of a thin film ceramic electrolyte with surface microelectrodes is modeled via direct numerical solution of current conservation. Faradaic and non-faradaic currents at the electrode-electrolyte interface are modeled phenomenologically using a formulation based on the Butler-Volmer equation. The model is able to reproduce complex, experimentally obtained impedance spectra for Pt/YSZ and Pt/GDC cells using only four adjustable, physically intuitive parameters: electrolyte conductivity, permittivity, exchange current density, and double layer capacitance. Equivalent circuit models typically used to fit these spectra instead require six or more adjustable parameters with ambiguous physical meaning. Notably, the model described here is able to capture a heretofore unexplained intermediate frequency arc seen in the experimental results. A parametric study enables the mechanism of the intermediate frequency feature to be identified as a spreading resistance in the electrolyte that vanishes at high frequencies due to low-impedance dielectric transport of current across the electrode-electrolyte interface. The fitting results are validated by comparison of the parameter values with literature reports.

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“…Several methods have been used to determine the effect of the ratio between contact radius a and film thickness L on contact resistance between flat thin films at different ranges. A mathematical model theorizes that thin film geometry causes the spreading resistance to be constrained to a much smaller region than the region where the spreading resistance takes place in non-thin films resulting in a lower contact resistance than that predicted by Holm and that contact resistance decreases with decreasing film thickness [1]. These results were valid only for values of a/L less than 0.5 [1].…”

Section: Introductionmentioning

confidence: 94%

Contact Resistance in Flat-on-Flat and Sphere-on-Flat Thin Films

Read

Lang

Slocum

et al. 2010

2010 Proceedings of the 56th IEEE Holm Conference on Electrical Contacts

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The dependence of contact resistance on force between flat, thin-films is thought to be different than that in bulk materials [1]. Multiple mathematical and finite element models have attempted to model this dependence but have been limited in the ranges over which they are valid [1,2]. Experimental results have shown that the contact resistance between flat, thin films is greater than that predicted by Holm theory when the Holm equivalent radius is greater than the film thickness for gold films of thicknesses between 0.1 and 0.5 μm [3]. This paper fits an equation to the FEM results presented in [2] and the experimental results presented in [3]. New experimental results between gold sphere-on-flat contacts of film thickness 1 μm and contact radii of 20 and 40 μm are presented and the results are compared to those predicted by the equation fitted to the previous FEM and experimental flat-on-flat contact results. As with the thin film flat-on-flat contacts, the thin film sphere-onflat contacts also have a contact resistance higher than that predicted by Holm in the region where the Holm equivalent radius is greater than the film thickness. Also examined is the transition in the force v. contact resistance relationship at the point where the Hertz radius of contact becomes greater than the Holm equivalent radius of contact.

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Constriction Resistance of Thin Film Contacts

Cited by 43 publications

References 6 publications

Evaluation of Anisotropic Conductive Films Based on Vertical Fibers for Post-CMOS Wafer-Level Packaging

Evaluation of Anisotropic Conductive Films Based on Vertical Fibers for Post-CMOS Wafer-Level Packaging

A Precise, Reduced-Parameter Model of Thin Film Electrolyte Impedance

Contact Resistance in Flat-on-Flat and Sphere-on-Flat Thin Films

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