I would vote for copper dissolution due to lead free HAL. The HASL
process can quickly remove copper in the PTH. Lead free HAL Rework and
your assembly process may advance the condition. A microsection of a
discrepant PTH would answer that question readily.

  
Paul Reid 
Program Coordinator  
PWB Interconnect Solutions Inc. 
235 Stafford Rd., West, Unit 103 
Nepean, Ontario Canada, K2H 9C1 
613 596 4244 ext. 229  
Skype paul_reid_pwb 
[log in to unmask] 
 

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