-- [ From: Douglas C. Jeffery * EMC.Ver #2.10P ] -- Tom Hybiske asked about "the inclusion or exclusion of nonfunctional lands from internal planes or signal layers"... We have been asking that non-functional pads be removed on dense designs (.005" lines and spaces) to reduce the incidents of .005" spacing. This improves the manufacturing window for imaging and etching these layers. On some designs we prefer to leave the pads in as they act as filler for lamination( when a signal layer is very sparse). All in all for MLB's up to 12 layers I feel the pads should be removed to help "clean" up the image and improve the yield. We haven't addressed the issue of pth support from the pads as we feel that an uninterrupted hole wall will plate better than one with lots of surface changes. The lack of pads does improve drill wander and help with tight registration designs especially with todays ultra thin designs that can be 30% to 40% copper (thickness). Doug Jeffery Electrotek [log in to unmask]