You are right. We have re-prepared the samples several times, because we
doubted that the gold thickness was correct.  Polished with various grids
4,000 to 7,000. Used weak etchants and other tricks, but got same result.
Thin areas, just nanometers of gold. Thick areas, more than one micrometer.
I'm not sure, but in the cross section, it looks like being a little copper
between the nickel and the gold. Furthermore, the nickel seems to have
microcracks all the way from the gold and down to the copper.

Did I tell you that the board's gold looks quite normal at the arrival from
China, but looks reddish after the assembly is finished? Like diffused
copper in gold. I've seen copper diffuse through nickel, but then the nickel
was very thin.

Inge


----- Original Message -----
From: "George Milad" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, October 17, 2006 6:48 PM
Subject: Re: [TN] ENIG problem


> Ingemar,
>
> One thing attracted my attention when I read your posting. You  stated
> that
> the gold was very thick (>1um)
>
> As a supplier of ENIG Chemicals and the chairman of the plating committee
> that specified ENIG as surface finish, I can tell you that the process is
> not
> capable of depositing that thickness of gold on nickel.
>
> The only time this gold thickness may be encountered is when the nickel
> plating skips the pad (does not or fails to plate) and the gold is
> deposited
> directly on a copper pad.
>
> Verify the Ni thickness on that specific pad that had the very high gold
> deposit thickness. this may give us a clue as to what is behind the
> failure.
>
> Regards
> George Milad
> George Milad
> National Accounts  Manager for Technology
> Uyemura International Corp (UIC)
> 249 Town Line Rd
> Southington CT 06489
> [log in to unmask]
> Cell: (516) 901  3874
>
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