Hard to say for sure but looks like the board maker didn't prep the copper very well before plating. Some spots definitely look as though the nickel is gone. I have seen similar on emersion silver boards. 


-----Original Message-----
From: Frank L Norman [mailto:[log in to unmask]]
Sent: Monday, July 28, 2003 12:26 PM
To: [log in to unmask]
Subject: [TN] Wave solder process issue on ENIG pwa


Technet,

Looking for comments for the following...

PWA's experienced solder wetting difficulties to plated through holes
including via's during the wave solder process and are unable to be
touched-up by hand. PWA's are two sided multilayer with combination of
rigid board and flex circuits finished with Electroless Nickel Immersion
Gold (ENIG) for a thickness of 100 microinches of Nickel and 5 microinches
of Gold. Top side SMT components were reflowed and bottom side SMT were
wave soldered with excellent results, but as you can see in the pictures
the plated through holes on the wave soldered side had wetting issues.
Interesting thing is the non wave solder side through holes have good
wetting.

SEE PICTURES of pwa's in question at this website.

http://www.ripus.com/images/pwa/index.htm

Regards,
Frank Norman
Manufacturing Support Engineer
Raytheon, Space and Airborne Systems (SAS)
(805)879-2745
[log in to unmask]

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