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March 2007

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Subject:
From:
Dennis Fritz <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, [log in to unmask]
Date:
Tue, 20 Mar 2007 13:31:37 EDT
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text/plain
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In a message dated 3/20/2007 12:33:06 P.M. Eastern Daylight Time,  
[log in to unmask] writes:

I have  noticed a trend with our ENIG PCBs where Nickel is growing beyond
the  Copper and onto the FR4 and Soldermask. I would like to know:

*   Is it a cause for concern with our assembly process?
If the growth causes solder bridges, yes, it will affect assembly


*    Is it a cause for concern for the end  user?
Again, if the growth violates minimum spacing requirements.  Also, if  the 
extraneous nickel does not have good adhesion, it could fracture off the  board 
and cause shorts at another location. 


*    How is it caused?
Sounds to me like the activation process for nickel to plate on the copper  
pads is out of control.  It is activiting insulators - laminate and mask to  
now plate with electroless nickel.


*    How could it be prevented?
Proper operation of the preplate chemistry before the electroless nickel  
bath should only activate the copper pads.  
 
Denny Fritz
MacDermid

 



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