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