In-Situ Warpage Characterization of BGA Packages with Solder Balls Attached During Reflow with 3D Digital Image Correlation (DIC)

摘要

The decreasing size of solder joints leaves limited tolerance of allowable warpage range for successful assembly. Understanding the electronic packages' behavior during the reflow process becomes one of the most important tasks in developing assembly process and assuring reliability. Three-dimensional (3D) digital image correlation (DIC) plays an important role in quantifying warpage of BGA packages under thermal loading. To measure warpage of the substrate surface of a BGA package, conventional 3D DIC technique requires removing the solder balls, which takes the risk of damaging the solder mask surface and influences on measurement accuracy. Three parameters of 3D DIC (camera angle, facet size and facet step) are studied on the effects of data integrity and accuracy to realize warpage measurement while solder balls are attached to the packages. This method introduces novel settings of these parameters compared to current 3D DIC requirements, and summarizes a guidance for implementing nondestructive warpage measurement with different sizes of solder balls and camera resolutions.