Mark, Rudy and George gave you excellent information on the plating processes. I'll focus more on application. All the Au plating processes will yield a smooth enough finish for fine pitch soldering, however, Immersion best guarantees complete oxide protection of the Nickel, which is actually what you're soldering to, AND minimizing the amount of Au that will be dissolved into the solder joint. This removes concern about Au embrittlement of the solder joint. Add the stability/repeatability of the Immersion process and there you go. Soft Au is typically specified for Au wire bonding applications and is not associated with the Immersion process which is too thin for Au wire bonding (but Immersion Au can be suitable for Al wire bonding). Regards, Bruce Misner > ---------- > From: Mark Rusciolelli[SMTP:[log in to unmask]] > Reply To: TechNet E-Mail Forum.;Mark Rusciolelli > Sent: Friday, April 05, 2002 8:23 AM > To: [log in to unmask] > Subject: [TN] Gold Plating > > I'm a little confused about gold plating as a solderable finish > for circuit > boards and was wondering if anyone can clarify a few points. > > Most of our PCB's are have a hot air solder level finish, but > finer pitches > and smaller parts are requiring us to look at boards with flatter surfaces > and it looks like Nickel-Gold finishes have become somewhat popular. > > From what I understand, gold can be applied electrolyticly, > electroless > plating, or by immersion. (I don't really understand the difference > between > electroless and immersion). Is any one method superior to the others? It > seems like immersion leaves the thinnest amount of gold. Does immersion > leave the flattest surface as well? > > Furthermore it appears that you can get hard and soft gold, at > least with > an electrolytic process. Is one better than the other? > > I appreciate any help. > > Mark Rusciolelli > Nexus Custom Electronics > > -------------------------------------------------------------------------- > ------- > 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 > -------------------------------------------------------------------------- > ------- > --------------------------------------------------------------------------------- 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 ---------------------------------------------------------------------------------