Technet strips off attachments, so your pic isn't visible. Look for an email
from Terri Houston. She is a Manufacturing Engineer I work with.
What you appear to be asking for would require you to have a soldermask
defined pad for the bga attachment, and she can advise you of problems
there. EE's need to start listening to Manufacturing Engineers more!!

-----Original Message-----
From: Denis Lefebvre [mailto:[log in to unmask]]
Sent: Thursday, May 23, 2002 10:10 AM
To: [log in to unmask]
Subject: [TN] BGA Solderability


Technet;
As a designer, I diligently try to understand and account for fabrication
and assembly issues in my designs. It can be frustrating when working with
EE's that are not well versed in manufacturing as they request things that
you know are not good practice from a DFM viewpoint.
I have a case now where an EE is asking for a copper fill on BGA ground
pins. Since this is not easy to describe in a way that every one can
understand, I am including a small JPG to illustrate. It is a 356 pin BGA,
1mm pitch, 0.5mm solder lands.

I am convinced that this will not fare well when they try to solder this
part, yet the engineer insists on doing it this way. What argument can I
make, with supporting data, to persuade him? Simply telling him that I know
it is poor practice isn't cutting it! [Adjusting tie..."I tell ya, we get no
respect!"]


Denis Lefebvre, C.I.D.
Senior PCB Designer
408-542-3832
Finisar Corporation
1308 Moffett Park Drive
Sunnyvale, CA 94086
www.finisar.com <http://www.finisar.com/>

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