Symposium Conference Proceedings


Solder Voiding in Assemblies Using Via-In-Pad Ball Grid Array Design

Authors: Gurudutt Chennagiri, Satyanarayan
Company: SMART Modular Technologies, Tripod Technology, & Modules Technology Corporation
Date Published: 4/17/2013   Conference: Symposium


Abstract: Solder voiding in Ball Grid Array (BGA) package solder joints may compromise the solder joint integrity depending on the extent, size and location of the solder voids. This is especially true in cases where the size of the solder void is greater than 25% of the area of the solder joint, after assembling the component on to a Printed Circuit Board Assembly (PCBA), and is located at the pad interface of the solder joint. Constraints in the real estate area and move towards fine pitch array are some of the reasons warranting the use of via-in-pad designs. A concern associated with via-in-pad design is entrapped air within the micro via. The entrapped air has been shown to lead to the formation of solder voids. Filling and over plating the via (capping) is one way of preventing air entrapment within the micro via. Formations of large solder voids in (non-micro) via-in-pad designs, which are plugged with resin and capped, however, is another concern that needs to be investigated. This research paper explores the effect of factors such as the density or number of vias present within the given area array, via capping thickness, via plugging material, surface finish & baking on the formation of large solder voids in via-in-pad BGAs. Through a series of design of experiments the effect the different levels, for each of the factor, has on the solder void formation has been studied. Based on the results from these experiments guidelines to prevent the formation of large voids in via-in-pad ball grid arrays have been established and presented in this paper.

Key Words: 

BGA, via-in-pad, solder void



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