Good point, and may be applicable, but not responsible for the observed phenomenon.

Looks like the via fill material is a better match to copper than to the printed circuit board in the Z-direction, so the filled tube of copper is quite strong.  The overplating also made the whole pad pretty strong, and on the last cooldown, these "posts" stayed close to the same length while the PCB material shrank a bunch in the vertical direction, lifting the pads.

Wayne Thayer

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of John Parsons
Sent: Wednesday, March 13, 2013 7:06 PM
To: [log in to unmask]
Subject: Re: [TN] IPC-6012

Vladimir,

Take a look at the specification for wrap plating that came out as IPC-6012B Amendment 1 (Dec 2006).  I don't think I see any signs of the required wrap plating in those samples.

Regards,

John Parsons


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: March-13-13 3:51 PM
To: [log in to unmask]
Subject: Re: [TN] IPC-6012

Hi Vladimir!

Have your pictures posted now, they are here:

http://stevezeva.homestead.com/Overall_view.jpg

http://stevezeva.homestead.com/Close-up_of_crack_in_laminate_and_lifted_pad.
jpg

Never have seen anything like that before...

Steve

-----Original Message-----
From: Vladimir Igoshev. PhD
Sent: Wednesday, March 13, 2013 6:27 PM
To: Steve Gregory
Subject: Re: [TN] IPC-6012

Thank you Steve. Here they are.



--
Best regards,

Vladimir Igoshev. PhD
mailto:[log in to unmask]

SENTEC Testing Laboratory Inc.
11 Canadian Road, Unit 7.
Scarborough, ON M1R 5G1
Tel: (416) 899-1882
Fax: (905) 882-8812
www.sentec.ca 


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