Carl,



Certainly areas of low copper density on a layer can contribute to this type of defect. If the low density pattern is stacked on every layer of the board then this causes a low pressure area during lamination which increased the risk. Cu thickness is also to be considered. It is likely that following the advice of the fabricator will eliminate the problem.



Regards, 



John Parsons



-----Original Message-----

From: TechNet [mailto:[log in to unmask]] On Behalf Of Carl Van Wormer

Sent: April-26-17 6:51 AM

To: [log in to unmask]

Subject: [TN] PCB delamination at area with ground-plane cutout



We received pictures from our contract manufacturer, marked to show delamination occurring in 2 areas on our 6-layer boards.  The delamination areas were at the electrically isolated communication interfaces that were made with no copper on the power and ground planes to reduce capacitive coupling.  The response from the PCB manufacturer is:



​​​​​1)defect reason: we used our stock boards to run the thermal shock test, we see the de-lam is only taking place in the two areas without copper (pic 1.jpg),

    There is insufficient glue in this area that happened during lamination and that is why the de-lam is happening when the customer is assembling under the high temp, 2)correction action:  if the customer needs us to remake, we suggest to modify the design a little, pls see pic 2.jpg, we will fill the marked area with solid copper .

Please confirm if a remake is needed, we will arrange right away.



Steve Gregory has posted the pictures at:

http://stevezeva.homestead.com/Carl1.jpg (board cut open for evaluation at board house)



http://stevezeva.homestead.com/Carl2.jpg (picture showing where they want to add copper)



(and 2 pictures of the delaminated areas) http://stevezeva.homestead.com/Delamination_-_is_it_caused_by_missing_ground_plane__1_.jpg

http://stevezeva.homestead.com/Delamination_-_is_it_caused_by_missing_ground_plane__2_.jpg





Question to the group:  Will adding copper on the electrically isolated open areas eliminate this type of delamination?  We could add the copper, but not connect it to the system ground.



Thanks,

Carl













Carl B. Van Wormer, P.E., AE7GD

Senior Hardware Engineer

Cipher Engineering LLC

    21195 NW Evergreen Pkwy Ste 209

    Hillsboro, OR  97124-7167

    503-617-7447x303

    [log in to unmask]<mailto:[log in to unmask]>     http://cipherengineering.com<http://cipherengineering.com/>



This message may contain confidential and/or proprietary information, and is intended for the person/entity to whom it was originally addressed. Any use by others is strictly prohibited.  If I sent this to you by mistake, please be nice and delete it, and then tell me of my mistake so I can send it to the right person.