Once upon a time I did a drill study with new laminate trying to
optimize drilling parameters.  After drilling test boards they were
sent through the electroless line only.  This enabled us to see
the relative amount of gouging, drill debris and whether the glass
bundles had been cut sharpely or shattered.

It is important not to microetch these samples as the electroless
"disappears" if you do and the hole wall is not as visible.

There are no "tight" specifications or standards for hole wall roughness
just the critical defects that might result in the condition.

However by comparing the above attributes you can optimize the
hole wall after drilling and subsequently after desmear or etchback.

Susan Mansilla
Robisan Lab

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