Hi,
There is an article by Nicholas Biunno of Hadco on page 133 of Issue 5 of
"Future Circuits International" that covers the "Black Plague" quite
thoroughly.
Here is a very short over simplified summary:
Everybody looks at the nickel but the cause turns out to be the immersion
gold is too aggressive. The immersion gold works by corroding the nickel. If
it is too aggressive it takes away the nickel and leave phosphorous behind.
This makes it look like the phosphorous level is too high in the nickel
bath.
Robert Peterson
mailto:[log in to unmask]
Alternate Final Finishes, Inc.
166 Middlesex St.
N. Chelmsford MA 01863
Phone (978) 251-7429 Fax (978) 251-7219
http://www.AlternateFinalFinishes.com
-----Original Message-----
From: Hollandsworth, Ron [mailto:[log in to unmask]]
Sent: Tuesday, October 12, 1999 11:21 AM
To: [log in to unmask]
Subject: Re: [TN] Black Plague
Importance: Low
Franklin
We are seeing the problem mainly at our wavesoldering operation. We have
seen some, little, at the SMD workcell. We have checked our wavesolder
process and profile and it has not changed. The problem is lot number
dependent. A specific date code may have multiple lot numbers, and the
issue show up on one lot number only and not every board in the lot. Bare
board condition shows no early warning signs that we have detected at this
time. We have cross sectioned some boards to see if there may be a tell
tale sign, but nothing outstanding. We do have a couple boards in for that
cross sectioning at the present time. No data back yet.
Ron
-----Original Message-----
From: Franklin [mailto:[log in to unmask]]
Sent: Tuesday, October 12, 1999 9:41 AM
To: [log in to unmask]
Subject: Re: [TN] Black Plague
Ron,
Where are you first seeing this condition?
Is it on the bare boards?
Are the the assembler or fabricator?
How have you 'cleaned' these boards up in the past, if at all? (cleaned or
made the gold look better)
I'd like to offer whatever I can, your first message just did not have
enough information.
Franklin
-----Original Message-----
From: Hollandsworth, Ron < [log in to unmask] <mailto:[log in to unmask]> >
To: [log in to unmask] <mailto:[log in to unmask]> < [log in to unmask]
<mailto:[log in to unmask]> >
Date: 12 October, 1999 7:54 AM
Subject: Re: [TN] Black Plague
Franklin, POD, & Paul
You say there are ways to get around the Black Plague. Would you elaborate
please. Once again I see messages where others are experiencing this
problem but no absolute solutions. I have read the articles, tried the
erasers, stronger fluxes, and pad scraping. No relief. I have learned to
dislike Electroless Ni/ Immersion Au boards. I am thinking that HASL or
precision pad technologies are much better. At least you can perform your
soldering operation. A Circuit Card Assembly (CCA) with the Black Plague
can run up scrap costs real fast. Not to mention the possibility of late
shipment to the customer because of inability to solder. This is a real
problem if you are using Ni/Au boards. So far there are few comments and
the issue simply drops out of sight. Are platers/fabricators not
controlling their processes or is this a inhouse process issue. We have
checked our processes and find no change.
Ron Hollandsworth
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