[SI-LIST] Re: BGA routing
- From: "Ken Cantrell" <Ken.Cantrell@xxxxxxxxxxxxxxxx>
- To: "Patrick Jabbaz" <patrick@xxxxxxxxx>, <Ken.Cantrell@xxxxxxxxxxxxxxxx>, <darshanmehta2k@xxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Thu, 11 Nov 2004 13:30:25 -0700
Great! Looking forward to the article.
-----Original Message-----
From: Patrick Jabbaz [mailto:patrick@xxxxxxxxx]
Sent: Thursday, November 11, 2004 10:44 AM
To: Ken.Cantrell@xxxxxxxxxxxxxxxx; darshanmehta2k@xxxxxxxxx;
si-list@xxxxxxxxxxxxx
Subject: RE: [SI-LIST] Re: BGA routing
Ken
Regarding the VIA in PAD, we just had an IPC meeting regarding the
subject,
The Speaker Donald A. Carron
Director of Technology
TTM Technologies, Inc.
Santa Ana Division
Gave an excellent presentation on the topic VIA-IN-PAD "a new approach"
He explained in detail, the new process regarding via fill, to make a
long story short, the problems you mentioned regarding VIA In Pad, are a
thing of the past, quite a few PWB board fabricators now have the
capabilities to have standard drill vias filled with epoxy, and are
capped by conductive material to a very flat surface, I have used them,
and have looked through a microscope and they are flat, I could not even
tell that there was a via present just by looking at the board.
Regarding Microvias, it does require a different process, and they are
completely filled with conductive material, there is no air trapped
inside.
I will have the minutes from the meeting publish on IPC Route next week.
Inkra Networks
Patrick Jabbaz CID
Sr Board Layout Eng.
40971 Encyclopedia Circle
Fremont, CA 94538
Work (510) 249-4835
Mobile (408) 621-6533
patrick@xxxxxxxxx
-----Original Message-----
From: Ken Cantrell [mailto:Ken.Cantrell@xxxxxxxxxxxxxxxx]
Sent: Thursday, November 11, 2004 8:25 AM
To: darshanmehta2k@xxxxxxxxx; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: BGA routing
Darshan,
My understanding from the CAD guys is that you get a lot of cold solder
joints from outgassing at the via site, even with micro-vias. The fill
on a
via is never flat, there is a small void. When you flow the BGA on top
of
that, the trapped gas expands and forms an even larger void in the
ball-pad
interface.
Ken
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Darshan Mehta
Sent: Thursday, November 11, 2004 4:41 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] BGA routing
Hi All,
I have one general question regarding BGA routing. I have seen many BGA
boards and nobody puts via exactly below the BGA pad. Most of the times,
we
generate Fanout outside the BGA pad. Is there is a specific reason for
that?
I think we can save lot of space if we put via exactly below BGA pad. Is
there will be any problem if we put via exactly below the pad of BGA?
Thanks.
Best Regards,
Darshan Mehta
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