Is ENIG applied before or after soldermask? If after, wouldn't there only be a small area of Ni at the pad? Does this still have a significant effect? Blair >>> [log in to unmask] 06/15/05 06:24PM >>> Hi, Martin Werner has the numbers right. I put something on the forum a week or two back with a little more detail. I will copy it to you directly offline Thurs. a.m. It might help you. Basically, at the high frequency/high impedance levels, the signals move along the outside surface of the conductors due to the Hall effect (skin effect) of electron/hole recombination. Therefore the conductance of the different alloys becomes much more critical. During soldering of ENIG, the gold is absorbed into the solder joint, and you have an underlying conductor that is basically nickel. With immersion silver the silver is absorbed into the solder joint, and you now have a conductor that is essentially copper. While nickel's conductance is only slightly worse than copper, the addition of phosphorus needed in the plating process for ENIG brings nickel's resistance much higher. The signal loss of the nickel is approximately 10 times that of copper, per centimeter. This becomes more important at frequencies above 1Ghz. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier Sent: Wednesday, June 15, 2005 4:27 PM To: [log in to unmask] Subject: Re: [TN] RF board finishes Hi Martin, The electrical performance of Ni is not as good as Cu: 90 micro-Ohm/cm v. 1.67; 4.7 microDb/cm v. 0.6. My recommendation is iAg. Regards, Werner Engelmaier Engelmaier Associates, L.C. Electronic Packaging, Interconnection and Reliability Consulting 7 Jasmine Run Ormond Beach, FL 32174 USA Phone: 386-437-8747, Fax: 386-437-8737, Cell: 386-316-5904 E-mail: [log in to unmask], Website: www.engelmaier.com ******************************************************************* This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This footnote also confirms that this email message has been swept for the presence of computer viruses. www.hubbell.com - Hubbell Incorporated --------------------------------------------------- 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 -----------------------------------------------------