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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