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Date: | Fri, 16 Feb 96 10:02:00 EST |
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Following from the Electronics Manufacturing Productivity Center in
Indianapolis, prepared by Bill Goers:
"The basic statement or premise of "If there is a difference between the
board's coefficient of expansion and the part, the solder joint will crack"
is incorrect. The volume of solder in the joint determines the cracking
resistance of the joint. High temp solder joints act as "compliant lead".
Plastic BGAs have a very similar CTE to FR4 type boards.
The EMPF is involved with JPL in a BGA reliability study (plastic/ceramic
and metal).
We will be happy to work with Hitachi to develop their BGA manufacturing
processes. Please contact the HelpLine at 317.226.5616 or
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From: TechNet-request
To: technet
Cc: anderson_p
Subject: Protection of BGA Solder Joints
Date: 15 Feb 96 5:51PM
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Date: Thu, 15 Feb 1996 17:51:42 -0600
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From: [log in to unmask] (ROGER HELD)
Subject: Protection of BGA Solder Joints
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--
At Hitachi, we are considering moving to BGA technology during our
next model design phase. We are not very familiar with the
manufacturing process for this technology. We have come up with a
question we have not yet been able to resolve (as follows).
Solder joints on QFP's resist cracking due to thermal expansion
because the leads have some give due to a "spring" effect. With BGA's
there is no give between the board and the part except for the solder
joints. If there is a difference between the board's coefficient of
expansion and the part, the solder joint will crack.
1. Has anyone experienced this problem? How do you resolve it?
2. We are considering some sort of sealant material to protect the
solder joints and provide some thermal relief. Does anyone have
any good ideas for materials?
Anyone who can do a data dump on this for me will be greatly
appreciated! Thanks in advance,
Roger Held
Hitachi Computer Products
Norman, OK
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