Gold porosity testing was initiated to detect the potential of metallic
migration (copper migration).  In the event of the copper migrating through
the coating metals (nickel/gold), it would oxidize/corrode on the contact
surface and create an intermittence/open from from the tab area to the
connector.  Initially, it was done with a nitric bell jar test, but since
has evolved to an electrolytic type test.  Details of the testing may be
obtained from IPC-TM-650 and related IPC documents.  BellCore also has some
extensive documentation for Porosity.  I hope this helps, If you need more
data, Email Me.  JOHN
-----Original Message-----
From: Pratap Singh <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: Sunday, March 29, 1998 3:02 PM
Subject: Re: [TN] Gold Porosity


>Kelly Kovalovsky wrote:
>>
>> I am looking for some information on gold porosity as it applies to
common PCB
>> edge tab connector contacts. More to the point, I would like to know:
>>
>> What is a good working definition of porosity?
>> What is the common test(s) for porosity and the theory behind the test?
>> What are the common causes for test failure?
>>
>> Kelly Kovalovsky
>>
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>Kelly, IBM specs define gold porosity very well and have three test
>methods to test for gold porosity, GEL, Electrographic Paper and nitric
>acid vapor method.
>
>I have retired from IBM and have no direct access to specifications but
>you should be able to serach on the internal search facility.
>
>American Electroplaters' Society has several documents that talks about
>nature, cause and effect of the porosity in electrodeposits. Also look
>into plating magazine December 1969 article by A.A. khan " Porosity
>Testing Techniques in Gold deposits", very informative.
>
>By the way at which IBM site you are working? Let me know if you need
>further help.
>
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