Frank, Although ENIG can be put down before or after solder mask it is usually put down after solder mask. If you put down ENIG before solder mask every trace and feature gets coated with electroless nickel and immersion gold. The other think you forgot is that RF designers hate solder mask or flux or any foreign material on their RF strip lines because they fear it will effect RF performance. The nickel on the RF strip lines will most certainly have an impact on the RF impedance. Regards, George George M. Wenger, Andrew Corporation Reliability / FMA Engineer Base Station & Subsystems Group 40 Technology Drive, Warren, NJ 07059 (908) 546-4531 [log in to unmask] -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Ryan Grant Sent: Monday, December 27, 2004 10:53 AM To: [log in to unmask] Subject: Re: [TN] Immersion gold specification Hi Frank, Why is the Nickel thickness reduced for RF designs? Immersion Gold is typically done after soldermask, so the traces are still copper, and the gold pads become covered with solder after assembly. Therefore, the skin affect wouldn't apply to the nickel. Ryan Grant -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Frank Kimmey Sent: Thursday, December 23, 2004 11:31 AM To: [log in to unmask] Subject: Re: [TN] Immersion gold specification Well, now that Jeff has told you about the standard here is a little more. As Paul says, "it depends" Though ENIG is a great finish for today's designs there are some definite issues with the latest IPC standard. Depending on the type of design you may want to modify the callout to fit your requirements. 1. Use standard as a reference for digital designs (remind your fabricator that "black pad" is not acceptable) 2. Reduce the nickel thickness for RF designs as more nickel creates a bigger barrier for the RF to flow. Personally I callout 3 to 8 microinches of Immersion Gold over 50 to 150 microinches of Electroless Nickel. But then I am doing high powered, low loss required RF. Good Luck and have a Happy Holidays Hope it helps, FNK Frank N Kimmey CID+ Principal PCB Designer Powerwave Technologies Inc Office 916-941-3159 Fax 916-941-3195 Cellular 916-804-2491 -----Original Message----- From: Jeffrey Bush [mailto:[log in to unmask]] Sent: Thursday, December 23, 2004 10:10 AM To: [log in to unmask] Subject: Re: [TN] Immersion gold specification The current ENIG standard is IPC-4552. The spec on thickness for all classes is 2 uinch minimum for gold and 118-236 for nickel. Jeffrey Bush Director, Quality Assurance and Technical Support VERMONT CIRCUITS INCORPORATED 76 Technology Drive - POB 1890 Brattleboro, Vermont 05302 Voice: 802.257.4571.21 Fax: 802.257.0011 http://www.vtcircuits.com -----Original Message----- From: David Harman [mailto:[log in to unmask]] Sent: Thursday, December 23, 2004 1:01 PM To: [log in to unmask] Subject: [TN] Immersion gold specification Hope the network out here has a great holiday and successful new year. I have one last question for this year regarding plating standards and specifications. I am trying to call out gold immersion specification over nickel on my PCBA. My understanding is Mil-G-45204 type ll is no longer a valid specification. Is the industry standard 3 micro inches max - 1 micro inch min. (As long as the process can be controlled you should not have any nickel migration.) Is this correct. Can some one tell me how I would spec this out on my drawing and what standard is used in the industry for gold immersion over a an absolute minimum of .00005 nickel. Thanks David Harman --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 ----------------------------------------------------- ------------------------------------------------------------------------------------------------ This message is for the designated recipient only and may contain privileged, proprietary, or otherwise private information. 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