Are you sure this isn't chemical corrosion from leaked in etchant that had
a path through the copper cracks either during fab or microsection?
I have never seen plating burn show up in this manner.

Mike Luke




                                                                           
                                                                           
             Chris Mahanna                                                 
             <cmahanna@ROBISAN                                             
             .COM>                                                      To 
             Sent by:                  [log in to unmask]                
             IPC-600-6012                                               cc 
             <IPC-600-6012@IPC                                             
             .ORG>                                                 Subject 
                                       Re: [IPC-600-6012] opinion poll     
                                                                           
             08/16/2010 12:43                                              
             PM                                                            
                                                                           
                                                                           
             Please respond to                                             
             "(Combined Forum                                              
               of D-33a and                                                
                   7-31a                                                   
              Subcommittees)"                                              
             <IPC-600-6012@IPC                                             
                   .ORG>                                                   
                                                                           
                                                                           
                                                                           




Hi Lance,
No solder
Let me add another picture to the story.

-----Original Message-----
From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Lance A Auer
Sent: Monday, August 16, 2010 1:35 PM
To: [log in to unmask]
Subject: Re: [IPC-600-6012] opinion poll

Chris,

        I think your picture shows an "E" crack and the initial plating
has separated from the copper that was subsequently plated.   Is that
solder in the area where the platings are separated?

Thanks,
Lance





From:
Chris Mahanna <[log in to unmask]>
To:
[log in to unmask]
Date:
08/16/2010 10:21 AM
Subject:
[IPC-600-6012] opinion poll
Sent by:
IPC-600-6012 <[log in to unmask]>



Hi Everyone,

Attached is a picture of a thru-hole corner after thermal stress.  The
plating is pulse.  I believe the corner was 'burnt' because of the
geometry of the (conformant) negative etchback.  All the corners show
burn; some show blisters; only this one cracked.

In your opinion, what are the non-conformance(s) if any?


Thanks

Chris

______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________[attachment

"corner.jpg" deleted by Lance A Auer/US/Raytheon]


______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________

______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________(See
attached file: another corner.jpg)



______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________