Is it possible there was a glass fiber on that area when it was plated, leaving you with the original copper foil thickness?

The fiber was then removed prior to ENIG?



My guess at the cause.



Steven E Herring

Director of Engineering

Pennatronics Corp



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

From: TechNet [mailto:[log in to unmask]] On Behalf Of FTL Quality

Sent: Thursday, February 07, 2019 3:07 AM

To: [log in to unmask]

Subject: Re: [TN] "Wrinkle" on outer copper layer



Are you able to complete an XRF analysis on the Nickel thickness of the ENIG?



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

From: Tom Brendlinger

Sent: Wednesday, February 6, 2019 8:36 PM

To: [log in to unmask]

Subject: [TN] "Wrinkle" on outer copper layer



Hello TechNet,



I've recently received some boards that have a defect I've never seen before.



There is a linear depression in a 2oz outer copper layer on two out of 45 boards. One of the boards was on a solder sample panel, the other was assembled with the defect.



The depression has the appearance of a wrinkle or groove, it is approximately straight and square to the edge of the board. At its widest point it is about 0.006" wide, and as far as we can measure it is between 0.0015" and 0.002" deep. There are a couple of small delaminations nearby (on a panel that has not been reflowed).



I looked through IPC-A-600 and did not find anything about this type of issue. I don't have the equipment to microsection or x-ray the board, so I'm not sure whether the foil is damaged under the plating (Which is RoHS ENIG).



Hopefully this image link works:

https://snag.gy/Kx58Oy.jpg



Please let me know if you've seen this before or otherwise know how I can find more information.



Thank you!

Tom Brendlinger

Senior Electrical Engineer

Superpedestrian, Inc.