Doesn't appear to be pink ring - it looks like a blister within the board. 

Have you microsectioned to see where the problem is located.  I would send the
assemblies back to the board supplier and have them microsection and determine where the problem is located.  Or you could do the sectioning. 
Or one of the test labs could do the sectioning

It doesn't look like haloing.



Susan Mansilla
Robisan Lab