Doug, Did considerable work with Lee Ritchey back in 1984, or so, with impedance controlled, ECL, MLB's. We decided first, from a dimensional stability and laminate integrity standpoint, x-hatched reference planes would be the way to go. It was and I have some, or at least one, pretty picture to show the inner layer details. Without the graphic, the hatches were/are on whatever centers required. The traces were two directly associated/under/over the reference plane grid traces of about 25 mils, as I recall. The system did as proposed. The laminate integrity and dimensional stability was excellent and the electrical performance was as specified. Today's boards may find issue with the grid system. They often are so dense, they almost make something equal to the x-hatching as hole locations and sizes make swiss cheese out of everything. Earl --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------