My first thought was silver sulfide.
Were the PWBs stored in a high sulfur gas area?  Nearby a tire factory,
oil well or refinery, ot coal fired power plant?
mark


mark
Mark Woolley |PTRL Laboratory | Avaya | 1300 West 120th Ave |
Westminster, CO 80234  USA |


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Thursday, March 08, 2012 3:33 PM
To: [log in to unmask]
Subject: Re: [TN] Black substance

Hi Pat,

Got your pictures and have them posted. Sorry for the delay, but I'm
still 
running in low gear. Here they are, and all I can say is YIKES!

http://stevezeva.homestead.com/whisker1.JPG
http://stevezeva.homestead.com/whisker2.JPG
http://stevezeva.homestead.com/whisker3.JPG
http://stevezeva.homestead.com/whisker4.JPG
http://stevezeva.homestead.com/whisker5.JPG

These look like the classic silver/copper corrosion from being exposed
to 
reduced sulfur gasses such as hydrogen sulfide. Here's a good paper that

details it all:

http://chavant.net/new_site/files/pdf/HP_ImAg_Corrosion_Paper_ISTFA_2006
1.pdf

I would be very scared, very, very scared...

Steve



-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Thursday, March 08, 2012 11:25 AM
To: [log in to unmask]
Subject: Re: [TN] Black substance

Hi Pat,

Reply to me with the pictures and I'll get them posted...

Steve

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Goodyear, Patrick
Sent: Thursday, March 08, 2012 1:39 PM
To: [log in to unmask]
Subject: [TN] Black substance

Ok got a new one.    Found on the plated portion of a turret a black
fuzz,
also on the riveted backside and the plated portions of all of the lands

outside the soldered areas.
It cleans right off with alcohol leaves no residue, is crystalline in 
structure and grows away from the metal has a coral like appearance.

I have attached pictures but Steve is off today so don't know who else
can 
post.

Again a 40 year old board.

Any ideas????

Pat

.


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