There is a need for adhesion between copper layers. We bury filled vias in solderable pads all the time. If the cap plate layers lose contact with the wrap plate layer, then the signal is open. If I saw this condition in incoming boards, I would reject it for reliability concerns since the separation will likely propogate along the plating line. There was mention in a previous response about a anular ring type requirement, this would be a good approach.
Thanks,
Brad Toone
L-3 Communications
________________________________
From: IPC-600-6012 on behalf of [log in to unmask]
Sent: Fri 2/24/2012 8:27 AM
To: [log in to unmask]
Subject: Re: [IPC-600-6012] Via Fill on Surface Plate
Isn't there a chance if the cap becomes dislodged that it could end up causing a short elsewhere on the board, e.g., between fine pitch SMT pads with no solder mask dams? In general it could also be considered FOD if the pads become dislodged. I think there is a need for some requirement for copper to copper adhesion.
Also, there does appear to be copper-to-copper separation to some degree.
Scott A. Bowles
Staff Designer - Printed Circuit Designer IV
CM & Engineering Services
L3 Fuzing & Ordnance Systems
3975 McMann Rd.
Cincinnati, OH 45245
Office: 513-943-2483
Mobile: 513-208-9009
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-----Original Message-----
From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Byrne, Matthew J (US SSA)
Sent: Friday, February 24, 2012 10:11 AM
To: [log in to unmask]
Subject: Re: [IPC-600-6012] Via Fill on Surface Plate
It does matter if there is contact if it is a BGA via-in-pad. I think it should have a "contact" requirement of 25 µm, similar to that shown Fig 3-16 from IPC-6012, attached. But no, I don't know of a specific existing requirement.
Matt Byrne
607-953-9820
BAE Systems Controls Inc.
Huron Campus, Building 257
1701 North Street, Endicott, NY 13760
[log in to unmask]
-----Original Message-----
From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Paul Reid
Sent: Friday, February 24, 2012 9:11 AM
To: [log in to unmask]
Subject: Re: [IPC-600-6012] Via Fill on Surface Plate
Well here is my opinion;
It does not matter if the cap stays on the barrel of the PTH or not because it is not part of the conductive path. The conductive path is down the copper foil and electroplated part of the PTH. The cap if lifted would not cause and open. Until you stick a solder ball or bury it and put a microvia on a cap it is not part of the circuit. It is not required to have conductivity.
If you do not worry about trapped contaminants then, from a practical point of view, this should be acceptable.
Sincerely,
Paul Reid
Program Coordinator
PWB Interconnect Solutions Inc.
235 Stafford Rd., West, Unit 103
Nepean, Ontario Canada, K2H 9C1
613 596 4244 ext. 229
Skype paul_reid_pwb
[log in to unmask]
-----Original Message-----
From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Wendi Boger
Sent: February 23, 2012 2:37 PM
To: [log in to unmask]
Subject: [IPC-600-6012] Via Fill on Surface Plate
Everyone,
Can I get your option on the attached pictures. They show via fill material that has not been sanded as to flush with the surface. There is no evidence of separation between copper to fill or copper to copper.
The question is what is the intent of the spec and what criteria should be used to assess.
Thanks,
Wendi Boger
[cid:[log in to unmask]][cid:[log in to unmask]]
[cid:[log in to unmask]][cid:[log in to unmask]]
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