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Date: | Thu, 8 Nov 2018 19:40:18 +0000 |
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Yes, there are many papers out there on black pad, and they all seem to point to high P levels as an indicator of the possibility of BP. Just google Black Pad, phosphorus and you will get a ton of information on the subject. Look for Werner Engelmaier's papers on the subject. Kester has a number of very, very good papers on the subject as well.
As to why smaller pads plate up thinner on gold than the larger ones, again I am not a plating expert but I believe it is due to the self-limiting property of the plating process, smaller pads stop before larger areas do.
-----Original Message-----
From: Steven Kelly [mailto:[log in to unmask]]
Sent: Thursday, November 08, 2018 1:32 PM
To: TechNet E-Mail Forum; Stadem, Richard D
Subject: RE: [TN] Immersion gold thickness per 4552
Hi Richard,
So if I do a SEM and see higher than normal phosphorus issues I should be concerned and if I do not I am probably OK? And why do the small pads have more gold on them than the big pads? Regards Steve
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D
Sent: November-08-18 2:23 PM
To: [log in to unmask]
Subject: Re: [TN] Immersion gold thickness per 4552
.....and the hyper-etching leads to higher phosphorus levels which can lead to black pad issues.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ed Hare
Sent: Thursday, November 08, 2018 1:03 PM
To: [log in to unmask]
Subject: Re: [TN] Immersion gold thickness per 4552
Steven,
I believe it means that at higher gold thicknesses there is a higher probability of hyper-etching of the EN by the gold bath.
------------------------
Ed Hare
[log in to unmask]
> On Nov 8, 2018, at 7:03 AM, Steven Kelly <[log in to unmask]> wrote:
>
> Hi all,
> Is it normal to obtain thickness readings of approx. 2.5 microinches of gold on large pads and 5 microinches on small pads across a panel ? What does it mean under paragraph 3.2.2 that higher gold thickness (>4.925 microinches) may compromise the integrity of the nickel undercoat?
> Thanks in advance. Steve Kelly
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