Leo, In the "good ole' days", 1960 to 1996, we at Hewlett-Packard made our own multilayers by the tens of millions using a pattern-plating electrolytic Cu/Ni/Au process-more than anyone else in the world put together. We had 13 pcb facilities around the world. The thickness of Au did not have an effect on etching, eventually we reduce it to 0.1 microns Au. BUT, nickel had a profound effect, especially on undercut. I advise against using any acid enchant like CuCL2, as it will go after the nickel and any porosity in the gold. You should be using a good alkaline enchant, buffered to a near neutral pH and having its specific gravity controlled on the high side. We always used a Watts nickel, rather than a sulfamate-nickel, as it had less stress and would not be attacked along the grain boundaries. You can find the process documented in Coombs PCB Handbook, 4th Edition, as Clyde Coombs was the Marketing Mgr for the Printed Circuit Div of H-P in those days. I was the Engineering Mgr of the biggest PCB shop in those days, before the OEMs started closing them down and getting out of the manufacturing business. Happy Holden Asian Pacific Materials Lin Leo <[log in to unmask]> Sent by: TechNet <[log in to unmask]> 05/27/2006 03:25 AM Please respond to TechNet E-Mail Forum <[log in to unmask]>; Please respond to Lin Leo <[log in to unmask]> To [log in to unmask] cc Subject [TN] Electrolytic Ni/Au in DES Hi, Does anyone have experience on electrolytic Ni/Au(Au thickness: ca. 12~20 micro-incheses; Hard gold Au-Co alloy) acting as etching resist in DES(developing-CuCl2/HCl-stripping) process? Does Au thickness have impact on etching solution attack? Thanks Leo --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- ___________________________________________________ ??? Yahoo!???? ?? 7.0??????????? http://messenger.yahoo.com.tw/ --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------