Prediction of Lateral and Normal Force-Displacement Curves for Flipchip Solder Joints

Published

September 1, 2001

Author(s)

Daniel Wheeler, Daniel Josell, James A. Warren, William E. Wallace

Abstract

We present the results of experiments and modeling of flip-chip geometry solder joint shapes under shear loading. Modeling, using Surface Evolver, included development of techniques that use an applied vector force (normal and shear loading) as input to determine a vector displacement of the pads connected by the solder joint (standoff height and misalignment). Previous solutions solved the converse problem: fixed displacements used to determine required applied force. Such solutions were inconvenient for applications, where the applied force (chip weight) is known. Also, for geometric and materials studies of solder joint shapes involving multiple parameters, determining the equilibrium displacement from applied force by bracketing solutions could become computationally expensive. Measurements of solder joint standoff height and misalignment as functions of the applied force (normal and shear), solder volume and pad diameter are presented. Experiments were carried out for solder ball diameters from 15 mil (0.029 mm(superscript 3) volume) to 6 mil (0.0019 mm(superscript 3) volume) on pads of diameter 0.64 mm and 0.35 mm. Fitting of simulation to experimental results gave optimised values for the contact angle and surface tension of the solder which were consistent with measured and literature values.

Proceedings Title

Computational Modeling of Materials, Minerals and Metals Processing, Conference |||The Minerals, Metals and Materials Society (TMS)

Conference Dates

September 23-26, 2001

Conference Title

Minerals, Metals, and Materials Society

Pub Type

Conferences

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Keywords

Flipchip, Solder, Surface Evolver, underfill

Citation

Wheeler, D. , Josell, D. , Warren, J. and Wallace, W. (2001), Prediction of Lateral and Normal Force-Displacement Curves for Flipchip Solder Joints, Computational Modeling of Materials, Minerals and Metals Processing, Conference |||The Minerals, Metals and Materials Society (TMS), [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=853056 (Accessed April 27, 2024)