1 April 2004 Inspection of micro-solderballs on a semiconductor bumped wafer using optical shadowgraph
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We describe a simple way to effectively measure the height of a micro-solderball of a micro-ball grid array (micro-BGA) on a bumped wafer. The proposed method derived using a white-light illumination source can perform a speedy whole field inspection of the micro-solderballs. The optical system consists of a white-light telecentric configuration and a long-working-distance microscope with a telecentric objective. The optical axes of the illuminating light and microscope are symmetrically arranged with respect to the normal of the test surface and hence the technique is applicable to optical measurement on a mirror-like test surface, such as a silicon wafer. The height of a solderball is computed from a simple formula based on the geometry of the specimen and the system configuration. Experimental results demonstrate that the height of a micro-solderball can be readily measured with accuracy in the order of micrometers.
© (2004) Society of Photo-Optical Instrumentation Engineers (SPIE)
Cho Jui Tay, Cho Jui Tay, Shi Hua Wang, Shi Hua Wang, Chenggen Quan, Chenggen Quan, } "Inspection of micro-solderballs on a semiconductor bumped wafer using optical shadowgraph," Optical Engineering 43(4), (1 April 2004). https://doi.org/10.1117/1.1668284 . Submission:

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