Dave, Thanks for the feedback. I did get some specifics on IPC-4552 proposed recommendations from the committee co-chair that we're going to put in our requirements. Regards, Rick Thompson -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of [log in to unmask] Sent: Thursday, January 31, 2002 6:37 AM To: [log in to unmask] Subject: Re: [TN] ENIG Thickness Standard? Good Morning TechNet! Rick, I have a very different perspective on ENIG than Peter so here is some food for thought. There is a specification for ENIG - IPC-4552 - which is in final ballot and should be release in the March/May timeframe. I recommend getting a copy. It's my opinion that the specification is quite useful considering there is no other specification available for industry use. The ASTM B488 specification is not a workable solution for electronics applications. There was a great deal of committee discussion on the electroless nickel plating thickness. The nickel thickness is very much viewed as application specific, for example, RF designers desire minimal thickness (30-50 uinches) as opposed to connecting applications which use 200 uinches. Rockwell Collins is successfully using 2-5 uninches for the immersion gold thickness and 50-150 uinches for the electroless nickel thickness in avionics applications and we intend on using the IPC-4552 specification in our documentation. Additionally, 50 uinches of electroless nickel is very adequate as a diffusion barrier as both the nickel/copper and nickel/gold phase diagrams demonstrate a wide range of immiscibility The only instances I have seen a 50 uinch electroless nickel thickness not be adequate was for pwbs which were subjected to repetitive thermal excursions (e.g. lots of rework, or 4 reflow passes). Using an immersion gold thickness of 6 uinches will not guarantee you solderability - the 4552 committee demonstrated that (by conducting testing) that 2 uinches of immersion gold can be steam conditioned and still provide expected solderability coverage. Teaming with your ENIG vendor, understanding their plating process control practices and requiring some level of solderability testing is the best way of insuring solderability. Good Luck. Dave Hillman Rockwell Collins [log in to unmask] [log in to unmask]@ipc.org> on 01/30/2002 09:03:53 PM Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond to [log in to unmask] Sent by: TechNet <[log in to unmask]> To: [log in to unmask] cc: Subject: Re: [TN] ENIG Thickness Standard? Rick, I went through this pain a while ago, and got a lot of tremendous help from Ingemar Hernefjord in particular. I believe there is no released standard for ENIG, though there is an empirical spec IPC-4552. It does not contain a lot of useful detail, though. I specify 5 microinches (0.12 microns) of Gold over minimum 235 microinches (6 microns) Nickel for my boards, after reading a number of studies and failure reports. In fact I was recommended to use 250 microinches of Nickel, but this would have made our boards too thick. The thicker gold layer minimises porosity and therefore oxidation to the underlying Nickel layer. Older thinking was for around 100 to 120 microinches Nickel, but studies by Eriksson and others concluded that with the growth of gold flashing through the Nickel from one side and Cu/Ni intermetallics on the other side of the plating, that a thicker Nickel layer would offer the boards a longer solderability shelf life and greater solder joint reliability. Hope this helps a bit. Certainly, I haven't experienced any problems with soldering or mounting of components on boards to this spec. Peter Rick Thompson <rthompson@VENTURAELECTR To: [log in to unmask] ONICS.COM> cc: (bcc: DUNCAN Peter/Asst Prin Engr/ST Sent by: TechNet Aero/ST Group) <[log in to unmask]> Subject: [TN] ENIG Thickness Standard? 01/31/02 08:36 AM Please respond to "TechNet E-Mail Forum."; Please respond to Rick Thompson Is there a standard for the plating thickness of the ENIG surface finish? I've searched the archives and didn't find anything. Based on a customer request we had increased the requirement for the electroless nickel to 200u inches. A couple of our board vendors are telling me that that is excessive and that anything over 100u inches is overkill. I've seen references in the archives for anything from 120u inches to 200u inches. What (if anything) is considered standard for this finish? Thanks for your inputs. Rick Thompson Ventura Electronics Assembly 2655 Park Center Dr. Simi Valley, CA 93065 +1 (805) 584-9858 x-304 voice +1 (805) 584-1529 fax [log in to unmask] ------------------------------------------------------------------------ --------- 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 ------------------------------------------------------------------------ --------- [This e-mail is confidential and may also be privileged. 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