Depends on what is meant by balanced glass styles. I have commented before on this and prefer unbalanced constructions within each dielectric thickness requiring multiple plies. The caveat is using homogeneous styles to promote dimensional stability. As an example when 5 mil thickness is required it is advantageous, instead of using 2 plies of 1080, to use a single ply of 106 and one of 2113 to acheive the same result. This allows a high resin to glass ratio, as the 106, for better bond characteristics and lower resin content, as the 2113, for higher dimensional stability. Plus, the two ply 1080 is very "juicy" and tends to slip about too much. If you are talking about using, say, a balanced construction on one board side, as several two ply 2113 styles per dielectric thickness, and another on the other side, this too has merit. I recently used a construcion, when the copper foil was heavier on one side than the other, consisting of several plies of 7628, sandwiched between two plies of 2113, to counter the copper imbalance to minimize bow and twist. This is a good question and has many answers depending on design requirements. 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 e-mail to [log in to unmask]: SET Technet NOMAIL To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest 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 ---------------------------------------------------------------------------------