Hi Rick,

Is the concern for moisture entrapment which could cause "pop-corning",
or, delaminating of the FR4  substrate, or, BT resin interface material?
Perhaps, the attempt could be to automate a pre-reflow bake out process
for high moisture content substrates???  As stated, extending soak times
to 5 to 10 minutes should be concerning for the flux.

Shean Dalton
Austin American Technology
www.aat-corp.com <http://www.aat-corp.com>

-----Original Message-----
From: Rick Thompson
Sent: 7/1/2004 11:03 PM
To: [log in to unmask]
Subject: [TN] Long Reflow Soak Times for BGAs?


I'm having a philisophical discussion with my boss regarding long reflow
soak times to improve soldering under BGA devices. Is there anything to
be gained by extending soak times at the 150C level from 60-90 seconds
to 5-10 minutes? I've never seen times this extended and am wondering if
they make sense in some situations? The boards in question are not
terribly difficult, .063" thick, 14 layer, 12x16 inches with maybe a
couple thousand components on top. Any comments on this practice?

Thanks in advance,

Rick Thompson

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