If you perform a Knoop hardness test but use a ball indenter instead of a diamond, you can tell the difference between hard gold over nickel and soft gold over nickel. (This method does not give you a true hardness measurement, however).
You do need to use a good scope and be able to see the indentation clearly, and have a known sample of both for comparison. I am not sure if the exact same process can be used with a Vickers, but I just assumed it can because it should be able to impress with a 100gram weight. The Knoop test works well because it does not induce the cracking that the Vickers sometimes does.
From: [log in to unmask] [mailto:[log in to unmask]]
Sent: Wednesday, November 02, 2016 12:07 PM
To: Forum, TechNet; Stadem, Richard D.
Subject: Re: [TN] Test
Richard,
I'm confused with your post. Your statement about Vickers hardness test can tell the difference in hardness between 5 uinches of "hard" gold from ENIG, which is immersion plated and the approximately 40 uinches of soft gold used for wirebonding is just not correct. First the 5 uinches of immersion gold plating on ENIG is "soft" gold not "hard" gold. Secondly, you really can't use Vickers to measure the hardness of 5 uinches of immersion gold on ENIG. Five uinches of immersion gold is too and the Vickers hardness measurement will really give you an indication of the hardness of the underlying electroless nickel. I know there are people in the industry who are trying to use nano-hardness measurements to measure the hardness of thin platings but I haven't seen any encouraging results that it is accurate.
George
________________________________
From: "Richard D. Stadem" <[log in to unmask]<mailto:[log in to unmask]>>
To: [log in to unmask]<mailto:[log in to unmask]>
Sent: Wednesday, November 2, 2016 9:15:17 AM
Subject: Re: [TN] Test
I agree. The Vickers hardness test I posted at the beginning of this thread is the best method. It can tell the difference in hardness between 5 uinches of "hard" gold from ENIG, which is immersion plated and the approximately 40 uinches of soft gold used for wirebonding applications.
Remember the original question was if there is a test to determine if the finish is hard or soft gold, not the thickness.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Gerry Gagnon
Sent: Wednesday, November 02, 2016 7:59 AM
To: [log in to unmask]<mailto:[log in to unmask]>
Subject: Re: [TN] Test
Andy I'll give you a pass! More detail for history buffs.
If we are talking about a true hard gold for hi-rel connector/contact/PWB Tab applications, we are talking about a cobalt modified gold electroplated from an acid gold cyanide solution electro-plated over a low stress nickel. Solution looks like grape Kool Aid.
The test for determining the hardness of the gold is to use a Vickers diamond indenter. Be aware that to do the test, you must electroplate a thick deposit of gold from the production plating bath over the nickel. I remember using 200 micro-inches minimum gold thickness for the test. The reason for the heavy thickness is to be sure there is plenty of bulk gold below the indenter, otherwise you are testing the hardness of the nickel under-plate, copper, and laminate.
Hard gold plated to 100 micro-inches over 300 micro-inches will pass the "old" nitric acid porosity and easily pass the more modern variants using a few "wiping type" connector insertions before the nitric acid porosity test (which is worst case (compared to a LIF or ZIF.
Due to gold cost, the thickness went down to 70 micro-inches, then 50, then 30, then 15, to the point of who cares. None of this stuff will pass the original nitric acid test.
________________________________
From: TechNet <[log in to unmask]<mailto:[log in to unmask]>> on behalf of Giamis, Andy <[log in to unmask]<mailto:[log in to unmask]>>
Sent: Tuesday, November 1, 2016 10:45 AM
To: [log in to unmask]<mailto:[log in to unmask]>
Subject: Re: [TN] Test
Hi Victor,
The great and all-knowing Wikipedia says hard gold often contains a small amount of cobalt or nickel.
I am also not an expert, but I believe hard gold is an electrolytic process. Although the electrolytic process can be stopped any time, typically target thicknesses are considerably thicker (30 micro-inches or more). If you are looking at 5 micro-inches, I'd guess it is immersion gold. The best action is to ask the supplier. If that's not an option, try EDS looking for cobalt. That's no guarantee, but positive results for cobalt would be informative. 5 micro-inches would be too thin to look for nickel. Good luck.
Did I pass the test?
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of [log in to unmask]<mailto:[log in to unmask]>
Sent: Tuesday, November 01, 2016 7:19 AM
To: [log in to unmask]<mailto:[log in to unmask]>
Subject: Re: [TN] Test
Fellow TechNetters:
I did not receive a response the FIRST time . therefore I pose the inquiry once again.
"Is there a test or method to determine if gold plating is hard gold or ENIG? XRF will determine thickness of gold but will not verify plating process. I am working with a measurement of 5 micro inches of gold."
Victor,
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of David Hillman
Sent: Tuesday, November 01, 2016 7:14 AM
To: [log in to unmask]<mailto:[log in to unmask]>
Subject: Re: [TN] Test
I don't know about the rest of the folks but I received an A+ and its rumored you received a C-
Dave
On Tue, Nov 1, 2016 at 7:09 AM, Douglas Pauls < [log in to unmask]<mailto:[log in to unmask]>> wrote:
> And what percentage of our grade is this test?
>
>
> Doug Pauls
> Principal Materials and Process Engineer Rockwell Collins
>
> On Mon, Oct 31, 2016 at 9:17 AM, Vadim Matveyev
> <[log in to unmask]<mailto:[log in to unmask]>>
> wrote:
>
> > Test
> >
>
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