Multilayer Inner Layer Seperation

I recently have been examining multilayer board failures. They are the classic inner connection failure between the foil and the through hole plating which I have not seen in many years. Has any one experienced any issues recently specifically relating to the introduction of direct plate processes in fabrication?

The failure is very obvious no evidence on the copper barrel surface of any adhesion to the foil or any copper fracture. The problem is obvious confirming the route cause is not. SEM will give you a nice picture, surface analysis will not be able to tell you a lot more due to all the other material possibly added during the sectioning of the board any suggestions or experiences to add.

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