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|Case Study: Radial Cracks in a Rigid-Flex Assembly|
|Keywords: Corrosion, Rigid-Flex PCB, ENIG|
|Crane Electronics in Redmond, WA, develops, qualifies, and manufactures a variety of implantable devices for leading medical companies. An unusual phenomenon was discovered during final inspection on a recent development project. On the flex portion of the board, visible radial cracks were found on annular rings around ENIG plated thru-holes. The thru-holes remain unpopulated during the assembly process at Crane and the defect is primarily seen on the top side of the PCB. Additionally, the occurrence of these cracks vary in frequency and severity. This paper describes the testing and analysis Crane Electronics has performed in order to determine the root cause of this defect.|
|Christopher Matsuoka, Process Engineer
Crane Electronics Inc.