Hi Donald,
There is one more thing not to be forgoten - component plating and it could (and sometimes does, but don't ask me why) have enough gold to cause the problem.
Vladimir
Sent from my Blackberry Wireless
Vladimir Igoshev, 519-888-7465 ext.5283
-----Original Message-----
From: TechNet <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Sent: Sat Apr 16 09:32:17 2005
Subject: [TN] ENIG Gold Embrittlement
I have heard a lot of differing views about Gold Embrittlement lately here
and I am curious, has anyone here found evidence that ENIG causes this?
From what I have read, the ENIG process lays down about 120 to 240 micro
inches of Ni and 2 to 4 micro inches of Au.
If you calculate the percent by weight of Au in the solder joint, you have
to have a very very thin stencil to even come close to having a problem
with the Au.
I have seen the following data from several different sources and most
recently in a workshop presented by George Milad and Donald Gudeczauskas of
Uyemura International Crop at APEX this past February. Their data shows
that with a 5-mil stencil and a Au thickness of 20 micro inches, the
percent of Au in the solder joint is 1.54%. Now of course, you are not
going to get 20 micro inches out of this immersion process and even if you
plated the Au, this is just at or below the threshold for Au embitterment.
So with a nominal thickness of say 5-micro inches of Au and a 5-mil
stencil, the percent by weight of Au in the solder joint would be 0.38%.
Would this be a problem? I don't think so. So has anyone evidence that it does?
Below are just two of many sites talking about gold embrittlement. These
have some neat pictures to go along with the text.
<http://www.npl.co.uk/ei/documents/gold.pdf>http://www.npl.co.uk/ei/documents/gold.pdf
http://www.alphametals.com/products/solder_solutions/pdf/soldergld.pdf
Donald Kyle C.I.D.+
281-285-7528 voice
281-285-8593 fax
[log in to unmask]
Schlumberger
Sugar Land Product Center (SPC)
Mail Drop MD155-1
155 Industrial Boulevard
Sugar Land, Texas 77478
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