It would definitely upset the planarity of the pad.
mark

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Wednesday, December 05, 2012 9:49 AM
To: [log in to unmask]
Subject: [TN] A PCB defect that is not specified by IPC

Hi Mordechai,

I have not seen anything like this before. I’ve posted your pictures so everyone else can see:

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

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

Could you share what the overall stack-up of this board was supposed to be and what prepreg thickness was used?

Steve

From: Mordechai Kirshenbaum 
Sent: Tuesday, December 04, 2012 3:16 PM
To: [log in to unmask] 
Subject: A PCB defect that is not specified by IPC


Hi Steve 

On routine visual inspection of an income PCB board we found a type of the defect
that is not specified in any of the IPC standards (e.g  IPC-A-600 Acceptability of Printed Boards).

It looks like  wrinkles on  pads  and conductors (see fig 1 in the attached file). We suspected that it was caused
by thick copper conductor on the second layer (under the outer layer).

We measured the copper and the dielectric thickness between the outer and the second layers
and found that the copper thickness on the 2nd layer was relatively high (70 micro-meter), and the 
dielectric thickness lower than specified (only 50 microns).

Have you seen similar defect?
What is the reliability impact? 
Is it acceptable for class 3?

Best regards
Mordechai Kirshenbaum
MOD, Israel

P.S. please feel free to post this question on the technet forum. 








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