>>> "May William D (Dean) CNIN" <[log in to unmask]> 09/19/01 11:17AM >>> Reading from IPC-6012A, I noticed the required starting thickness of an external conductor prior to plating for 1/8 oz base copper foil is 0.00020 inches and the starting thickness for 1/2 oz base copper is 0.00067 inches. Does anyone have an idea on how minimum starting thickness is determined for each weight of base copper? If minimum base thickness is exceeded by chemical milling and micro-etching processes, will it compromise board reliability assuming that there is sufficient electroplated copper to meet minimum total finished copper thickness? What possible problems may arise if these base minimums are exceeded? Thanks for your consideration! Ed McAtee NAVSURFWARCEN PHONE 812-854-3892 FAX 812-854-1174 --------------------------------------------------------------------------------- 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 ---------------------------------------------------------------------------------