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Date: | Mon, 14 Apr 1997 09:41:21 -0500 (EST) |
Content-Type: | TEXT/PLAIN |
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Dave,
Is the customer using Ceramic or Plastic BGA's? "Standard" 63/37 solder spheres
will allow for high coplanarity variations. "High Temp" is less forgiving.
In my past, we ran Plastic parts purposely warped then electrically tested them.
The parts measured .006 - .008" in variance for coplanarity prior to reflow. The
part was an 86 pin (9 x 10), .055" pitch device. After reflow we had 100%
success.
Hope this helps ya.
Allen
_______________________________________________________________________________
Subject: FAB/DES BGA flatness requirements
From: [log in to unmask] at ftl03
Date: 4/13/97 11:21 PM
Recently, a customer inquired as to whether we had seen an increase in the
flatness requirements for pwb's specifically due to the presence of BGA
devices. I replied that we had not seen any increase outside of 'normal'
warp and twist requirements even with boards that have BGA devices present.
This customer stated that for at least one BGA component manufacturer there
is a requirement of 0.3% warp and twist in the region immediately under the
BGA device.
Has anyone seen such a requirement? Can this be measured? Even after assembly?
Thanks in advance to all who reply...
Dave Rooke
Circo Craft - Pointe Claire
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