Can anyone help with a query on land around via holes. I have a copy of IPC-A-600 Rev E Aug 1995 which states for plated through holes the minimum land between the track and pad and hole must not be less than 0.002" as a minimum standard. This means that misregistration towards the track is not acceptable if the pad is reduced below 0.002" even if there is no actual breakout. On the other hand, the hole is allowed to break out of the pad in any other direction by as much as half the diameter. Clearly the two are incompatible with each other since with registration that bad there is bound to be breakout towards tracks in some areas. Has there been a revision specifically for via holes only, or is there any other specification relating to landless via holes as this criteria is impossible to meet on some designs. The implications of meeting this spec are to increase via pad size and/or reduce hole size which has implications for design density and manufacturing cost. Any views on this would be greatly appreciated. For production drilling on large panels, what minimum land do you think would be needed at the outset to guarantee minimum annular 0.002" on the finished panel taking account of drill size and etch reduction also? Best Regards -- Paul Gould [log in to unmask] Isle of Wight,UK ################################################################ 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 ################################################################