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CUF scaling effect on contact angle and threshold pressure

Fei Chong Ng (School of Mechanical Engineering, Universiti Sains Malaysia, Nibong Tebal, Malaysia)
Mohamad Aizat Abas (School of Mechanical Engineering, Universiti Sains Malaysia, Seberang Perai Selatan, Malaysia)
MZ Abdullah (School of Aerospace Engineering, University of Science Malaysia, Nibong Tebal, Malaysia)
MHH Ishak (School of Mechanical Engineering, University of Science Malaysia, Nibong Tebal, Malaysia)
Gean Yuen Chong (School of Mechanical Engineering, University of Science Malaysia, Nibong Tebal, Malaysia)

Soldering & Surface Mount Technology

ISSN: 0954-0911

Article publication date: 4 September 2017

201

Abstract

Purpose

This paper aims to present experimental and finite volume method (FVM)-based simulation studies on the scaling effect on the capillary contact angle and entrant pressure for a three-dimensional encapsulation process of ball-grid array (BGA).

Design/methodology/approach

With the development of various sizes of BGA packages, the scaling effect of BGA model on capillary underfill (CUF) process is investigated together with the influences of different industrial standard solder bump arrangements and dispensing methods used as case study.

Findings

The experimental results agree well to the simulation findings with minimal deviation in filling time and similar flow front profiles for all setups. The results revealed that the capillary contact angle of flow front decreases in scale-up model with larger gap height observed and lengthens the encapsulation process. Statistical correlation studies are conducted and accurate regression equations are obtained to relate the gap height to the completion filling time and contact angle. CUF threshold capillary pressures were computed based on Leverett-J function and found to be increasing with the scale size of the package.

Practical implications

These statistical data provide accurate insights into the impact of BGA’s scale sizes to the CUF process that will be benefiting the future design of BGA package. This study provided electronic designers with profound understanding on the scaling effect in CUF process of BGA, which may be extended to the future development of miniature-sized BGA and multi-stack device.

Originality/value

This study relates the flow behaviour of encapsulant to its capillary contact angle and Leverett-J pressure threshold, in the CUF process of different BGA and dispensing conditions. To date, no research has been found to predict the threshold pressure on the gap between the chip and substrate.

Keywords

Citation

Ng, F.C., Abas, M.A., Abdullah, M., Ishak, M. and Chong, G.Y. (2017), "CUF scaling effect on contact angle and threshold pressure", Soldering & Surface Mount Technology, Vol. 29 No. 4, pp. 173-190. https://doi.org/10.1108/SSMT-09-2016-0020

Publisher

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Emerald Publishing Limited

Copyright © 2017, Emerald Publishing Limited

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