Hi Dave!
My suspicion is that the pdb fab is proposing plating and then filling, followed by overplating. That way if breakout occurs on the final etch there will still be lots of plated contact to the escaping trace. I don't know if it makes Class 3--I suspect not. Trying to fill such a tiny through hole could be a problem if the board is thick. In any case, I prefer non-conductive via plugging material because the silver can create bad intermetallics at high temperatures--such as Pb-free reflow.
Wayne Thayer
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Dave Connitt
Sent: Tuesday, December 02, 2008 10:01 AM
To: [log in to unmask]
Subject: Re: [TN] Conductive Epoxy filled Vias
Joyce,
Our board house is concerned about meeting the 0.003" annular ring requirement with a drill and hole size that small. Remember they have to use a larger drill size to get our finished hole size. The conductive epoxy sounds like it will "relieve us" of that issue..
Dave Connitt
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Joyce Koo
Sent: Tuesday, December 02, 2008 9:16 AM
To: [log in to unmask]
Subject: Re: [TN] Conductive Epoxy filled Vias
Why not plated via?
--------------------------
Sent using BlackBerry
----- Original Message -----
From: TechNet <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Sent: Tue Dec 02 09:07:27 2008
Subject: [TN] Conductive Epoxy filled Vias
Hello List,
We are considering implementing a 0.80 mm pitch BGA on a development project and I have question about escape vias.
The part manufacturer recommends that we use a 0.019" pad with a 0.010"
drill. The board has to be a IPC-6012 class 3 PWB and I would like to have a 0.003 annular ring on the escape vias.
One of our board vendors suggested we use a epoxy filled via which would relieve us of the annular ring issue but I am not sure about still being a class 3 board. Does anybody know where I can confirm that epoxy filled vias are acceptable in a class 3 board?
Thanks,
Dave Connitt CID+
Printed Circuit Designer
KDI Precision Products, Inc.
A Wholly Owned Subsidiary of:
L3 Communications
3975 McMann Road
Cincinnati, Ohio 45245
Ph. 513- 943-2010 Fax 513-943-2288
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