Interesting. I always think gold is the functional layer and the nickel is there to prevent the copper migration to gold layers. Regards, Jason Zhao -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Steven Creswick Sent: Thursday, October 29, 2009 7:13 AM To: [log in to unmask] Subject: Re: [TN] Al wire bonding Anat, One can bond to the nickel [without the gold]!! This become especially easy with heavier wire sizes [>2 mil]. Typically, one uses an ENIG plating. The immersion gold results in a gold flash of ~2-5µinches The gold is merely there to protect the nickel from oxidizing too much. One actually bonds 'through' the gold layer to get to the underlying nickel. If given a choice, I like pure soft gold instead of a hardened gold. If you use ENIG, you may not get much choice in your gold. It is my opinion that the thermal history & chronology of the board has more of an inpact on wire bond reliability than simple plating. Eg - if one were to reflow the board, [maybe] clean it, then let it set in que for multiple weeks in a shop environment - I virtually guarantee you that you will note differences in bonding characteristics as compared to a virgin board. ENIG, or gold flash, is my answer. Keep them moving - don't let them set around, is my recommendation. Steve Creswick On Thu, Oct 29, 2009 at 3:38 AM, Anat Douek <[log in to unmask]> wrote: > > > Hi, > What is the min gold thickness required for reliable aluminum wire bonding > ? > Which gold type is prefered for this process? > It is needed for a military application. > > Regards, > Anat Douek > Process Engineer > Herley General Microwave Israel > tel. 972-25689455 > > --------------------------------------------------- > Technet Mail List provided as a service by IPC using LISTSERV 15.0 > 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=4.3.16for 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 15.0 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 15.0 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 -----------------------------------------------------