Question on annular ring and hole breakout. Why does IPC 276 permit breakout on outers on multilayers with PTHs? I can understand allowing it on inners, but not outers. Breakout on outers means that the pad associated with the hole does not cover all of the plated through hole. In outer layer processing the image of that pad protects the hole copper during etch. If resist or resist plating does not cover the holes during outer layer etch, won't the hole partially etch out. I can understand inners, but not outers. Is the spec too loose in this area? I have seen boards with outer layer breakout with partially etched out holes. [log in to unmask] ______________________________ Reply Separator _________________________________ Subject: Re: registration equipt Author: [log in to unmask] at Dell_UNIX Date: 4/25/96 12:14 AM Paul Waldner (Multiline Technology), Glad to hear from you again, Paul . Yes your equipment makes it more possible to prevent breakouts. In fact we could not get even close without some of it; however, we have designers pushing the 18 mil hole in the 25 mil land for the 10 layer multilayer and people trying to build them on the 18 x 24 and the 24x 36 panel.and with a 1 or 2 mil annular ring. Good luck even with the best equipment. Realistically, many people are building to the the IPC-RB-276 class 2 specification which allows 90 degree breakout. There has not been any problem that I am aware of except that the misregistration may cause shorting to a nearby trace. Phil Hinton Hinton PWB Engineering [log in to unmask]