OK. I didn't mean to confuse. The second image wasn't intended as an example of separation non-conformance.
It was intended to show the differential microetch of a burnt corner, due to the poor grain/porosity -as Fritz mentioned.
I couldn't send pictures of all the corners, so I sent one to show how I knew they were burnt.
If done properly, and with respect to one's own polishing processes, microetch is a wonderful tool to evaluate grain structure, porosity, fractures(and their depth), and separation. Of course usually we're talking electroless.
We have recently been correlating such observations to FIB milled samples using SEM. We have long trusted our microetch and our calibrated eyes, but it is amazing how well it actually correlates to the truth.
I think the point is that regardless of the risk, or assignability to a benign root cause, anything that was supposed to be plated together, by rule, must be, or it is nonconformant.
Chris
-----Original Message-----
From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Byrne, Matthew J (US SSA)
Sent: Tuesday, August 17, 2010 8:54 AM
To: [log in to unmask]
Subject: Re: [IPC-600-6012] opinion poll
The possibility of a separation at the knee between plating layers needs to be evaluated without microetching the cross section mount. If no separation is found then no defect should be called out. Microetching helps in failure analysis.
Matt Byrne
Manufacturing Engineer, PWB Technology
BAE Systems, Room 795
600 Main St, Johnson City, NY 13790
607-770-2267
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-----Original Message-----
From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Brown, Elaine
Sent: August 17, 2010 6:27 AM
To: [log in to unmask]
Subject: Re: [IPC-600-6012] opinion poll
It is non-conforming for both the crack and the plating separation.
The second picture is not so clear cut. If indeed the area at the knee is separation it is rejectable.
If it is differential microetching, it is not. Hard to tell from the photo.
I do not think we have any criteria for burning.
Elaine
-----Original Message-----
From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Chris Mahanna
Sent: Monday, August 16, 2010 1:19 PM
To: [log in to unmask]
Subject: EXTERNAL: [IPC-600-6012] opinion poll
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
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