SMTA International Conference Proceedings

The Challenges Of Non Wet Open BGA Solder Defect

Authors: Dudi Amir, Satyajit Walwadkar, Srinivasa Aravamudhan, and Lilia May
Company: Intel Corporation
Date Published: 10/14/2012   Conference: SMTA International

Abstract: There is an increase in the incidences of a SMT non-wet type of solder joint defect where the BGA ball does not solder to the printed circuit board (PCB) land. This defect is called Non Wet Open (NWO) and is a new phenomenon found during surface mount assembly reflow process. This defect is hard to detect with conventional inspection techniques and is sometimes misconstrued as a pad wetting issue or no paste printed.

This paper will report on the NWO defect in Flip Chip Ball Grid Array (FCBGA) packages observed after surface mount assembly. A previous study has described the formation mechanism of the non-wet defect [1]. This paper will define the NWO and describe the critical SMT assembly factors that can influence SMT yield. Results from the surface mount assembly processes, such as printing and reflow, as well as materials, that are affecting NWO defect formation will be shared in the following paper. Further, the paper will provide guidelines for a SMT engineer on how to mitigate the defect during surface mount assembly and optimize the SMT process for high yields. Finally, the paper will compare the NWO to the well known head on pillow defect.

Key Words: 

non-wet, open BGA, solder defect

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