This is not an issue if the plating is thick enough. We make fairly complex boards, a regular repeat order has the following features:- FR4 material Tg 140 154 mils thick 8 layers controlled impedance( microstrip and stripline) hole sizes 12 mil to 380 mil maximum aspect ratio 12.5 : 1 large plated slots (slots and large holes peck drilled) edge board plating hot air solder levelling Shadow direct plate system and pulse plating are in use. The boards are for use in main frame computer systems. There are more people doing this sort of thing than you would suppose. The boards are assembled without special precautions. Roger Hanmmond ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC web site (http://jefry.ipc.org/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ################################################################