Jamie;

The IPC conducted a Small Hole Round Robin test program a few years ago. The
number of the resulting report is IPC-TR-579.

In this report, it was noted that with certain aspect ratio holes, the
barrels failed in the resin rich areas. This indicates that non-functional
lands should be kept in the construction, for some types of holes. These
results led us to recommend that non-functional lands be kept on inner
layers, in the IPC-D-275 (1991). We also noted that with high layer counts
that it is desireable to remove some of the lands to reduce the compression
effect, during lamination.

Board fabricators like the removal of the lands, since it reduces the
opportunity for defects on the inner layers. However, the long term
reliability of the product should overide any decision about removal of inner
layer non-functional lands.

If you contact the IPC office, they can provide you with a copy of the
report.

Regards,

Gary Ferrari