Chris,
You might reduce the Beam energy and look again at the amount of Nickel
in the sample.  In most gold situations there is a nickel underlayer.
You may be picking up some nickel from the barrier layer beneath the
gold (assuming there is one).  If reducing the beam also reduces the
amount of nickel detected, yoru beam is penetrating the gold layer.
You may also want to verify the gold is its usual thickness by cross
section or Fluorescence.  (See Fischerscope XDAL or similar).
mark


mark
Mark Woolley |PTRL Laboratory | Avaya | 1300 West 120th Ave |
Westminster, CO 80234  USA |
Voice (Lab): (303) 538-2166 | email: [log in to unmask] |


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Chris Mahanna
Sent: Thursday, July 21, 2011 10:21 AM
To: [log in to unmask]
Subject: [TN] hard gold verification

Hello netters

We are an independent test facility.  Occasionally we are asked to
verify hard gold as part of bare board qualifications.
Our customers in these cases are usually the OEM supply chain QA.  The
buyer controls the source and Quality's only prayer is to run some first
articles through a 3rd party.
Our customer's chance of determining the hard gold formula used on his
boards is slim to none.  If it weren't for UL, they probably wouldn't
even know who supposedly built them.

Some time ago, we tried Nano-indentation and there is a related TechNet
thread.  It didn't work for us.
I assumed wear studies might be cost prohibitive, so we went to looking
for 0.2% cobalt by SEM-EDS.  This has worked nicely, until today.

Today we have 0.09% Co and 0.07% Ni.  From what I read, 0.1 Co is easily
explained by too rapid deposition, and hardness suffers greatly.  The
question is whether the Ni is supposed to be there as a hardener or not?
If yes, then 0.16% total is probably in the ballpark.  But what are the
chances it just got dragged there?  Does it matter?

Thanks in advance

Chris


Chris Mahanna
Robisan Laboratory Inc.




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