Hi Wayne - etchback isn't necessary for acceptable PTH reliability for some
products and product use environments so that may not be a contributing
issue. With that being said, I like etchback as it always makes the inner
connections better/more robust and in some product use environments having
etchback is necessary for long term product life. One question we haven't
asked as a group is " was etchback required in the fabrication
requirements?"

Dave

On Thu, Apr 19, 2018 at 9:11 AM, Wayne Showers <[log in to unmask]
> wrote:

> The real problem is that this PCB has no etchback, positive or negative
> (PCBs are defective).  As far as resin recession, yes the processing
> probably caused the separation, but once again, the PCB has no etchback.
>
> I would send that cross-section image to the PCB supplier and asked them
> if this is typical.  I suspect that they will realize it is a trap and
> either offer a crazy answer or admit that their is no etchback and offer to
> re-run/replace the PCBs.
>