HI everyone,

I'm attaching a link to a file showing something I'd appreciate your thoughts on. It's a cross-section of a QFN on an IAg board; Pb-free/no-clean process. As you can see from the EDS spectrum, that greyish stuff between pins has pretty much only Sn and O in its elemental composition.

I know there is burn flux residue around solder joints but that stuff doesn't have any C in it. The question I have is what is it.

I spoke to Bev and both of us are still puzzled.

Here is the link: https://www.dropbox.com/s/3wbj62vqjyhvj2y/What%20else%20it%20can%20be.pdf?dl=0

Thank you very much in advance.

Regards,

Vladimir 

SENTEC


______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________