Chris Gardini-ECG005 wrote:
>
> Seeking data/reports to address questions on the risks associated with
> Annular Ring size.  In particular, as the mis-registration of the of the
> mechanical drill to the PTH Pad moves towards a trace leading into the pad
> the potential for an 'open' to occur increases.  Concerns center around
> 'thin' ring passing ET, but in field stresses cause fracture and crack
> propagation to 'open' state.
>
> Thanks, Chris

Hi Chris -- I agree with Werner.  The Z-axis stress is the concern which
normally occurs, above the 125C tg, at soldering temperatures, around
260C. A second point to consider is the solderability issue. The annular
ring aids in the transfer of heat to the solder joint especially for
hand soldering during assembly or field repairs.
regards,
Arny Andrade
Sandia Labs/ret.