Jingwen Qin - IEEE Xplore Author Profile

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Micro-solder balls are commonly used in wafer-level ball grid array (BGA) packages as an interconnection medium. To measure the height of a micro-solder ball on a metal pad, we propose a white light projection method to avoid interference from pads in the shadow of the ball. The optical projection of a solder ball under the illumination of a parallel white light beam is studied, and the relationsh...Show More