This serious discussion could be fun. Considering today's single ply designs and requirements for constructions as, say, 4 mil dielectrics using, say, 2113 glass, there's not a lot of "squeeze out" happening. The resin to glass ratio is moderate or about ideal and when a specified press cycle is used, variations are minimal. Few folks are going to high pressure, not that it matters, or are changing recommended press cycles so few negative, or out of tolerance, changes should be observed concerning impedance. As you said, the press cycle is pretty much pre-determined for time, temp, and pressure. Therefore, as little consequence is observable, there should be very little change in the dielectric constant or the final impedance effects. Foil thickness and, more importantly, edge raggedness, as a result of operator process management ineffectiveness certainly is a major contributor to wider changes in the final outcome. With all this, I don't believe the press cycle to be a major factor unless it is greatly mis-managed. Getting to 25 ohms impedance, depending on design requirements, is a trick unto itself. MoonMan --------------------------------------------------------------------------------- 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 To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL 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 ---------------------------------------------------------------------------------