No brainer indeed Ed ; yo're dead right ; with more than 1um on leadless
yo're doomed .
As you went through IPC files ; you should have all contacts and references
;
I'd just add the time factor (or timebomb if you prefer) on intermetalics
growth (which shocks or vibro tests will not tell you) ;
if Werner shakes his grankids off he'll tell you something proper which you
may not have time for ;
we cycled gold 7 months to get something resembling reality (IPC-SM-785) .

See you

Paul Klasek
http://www.resmed.com

PS
Just a practical paradox ; there is an application where they might live :
implantables [ no vibrations ; and constant 37'C ] ; hehehe (is Steve on
holidays?)

Wish you luck with the management

> ----------
> From:         Knowles, Ed[SMTP:[log in to unmask]]
> Sent:         Tuesday, 6 April 1999 7:28
> To:   [log in to unmask]
> Subject:      [TN] Gold Embrittlement
>
> Please don't blast me on bringing this subject up again.  I have searched
> the TechNet archives and found lots of good information, and also noted
> that
> it is a somewhat sensitive subject, having been around for 30+ years.  We
> have a condition that I believe is clearly unreliable based on what I have
> read.  The condition is:
>
> - 4 lead LCCC's (leadless with castellations)
> - Approximately 50 microinches of glod plating on untinned castellations.
> - Untinned parts mass reflow soldered onto PWB's (parts were supplied on
> tape and reel, so subcontractors did not see that they were untinned).
> - Microsectioning shows a 50 to 100 microinch layer of Au/Sn intermetallic
> after soldering, on top of copper/nickel surface.  Au concentration
> averages
> about 25% in this intermetallic region.
> - These assemblies will be subjected to high vibration and long term
> (years)
> thermal cycling in actual use.
>
> Replacement of these parts would be expensive since they are on many
> boards
> installed in closed and tested boxes. For this reason, mangement is hoping
> that testing will qualify this condition.  I hate to see the affected
> program waste time and money, and am afraid they might even get a warm
> fuzzy
> and fly these parts.
>
> Can any of the numerous industry experts in this group give me something
> concrete to present to the program such as actual experiences or
> obtainable
> reports?  Is the above condition a no-brainer or is it not as bad as it
> looks to me?  I tried getting copies of the 2 reports listed in the
> J-STD-001 Handbook, but struck out.
>
> Thank you for your time.
>
> Ed Knowles
> Lockheed Martin
> [log in to unmask]
>
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