Hello Peter,
A safe way to make this determination is to define the slowest conveyor
speed, the required profile, the largest BGA, and, the acceptable
temperature delta across that BGA. Then, drill a hole thru the backside
of the board under the center of the BGA. Mount a thermocouple here on
the BGA's center most pad, and, mount another thermocouple in a corner
BGA pad. Next profile the board/BGA. Compare what you get with what
you expect. From there, you can make a determination if a five zone is
acceptable, or possibly acceptable.
In my experience, 5 reflow zones do give enough profile definition and
can be acceptable if the conveyor speeds meet required line speeds.
Note: Cooling (the downward side of TAL) warrants as much attention as
heating.
Hope this helps,
Shean Dalton
Austin American Technology
www.aat-corp.com <http://www.aat-corp.com>
-----Original Message-----
From: Crain, Peter (GE Energy)
Sent: 9/21/2004 11:43 AM
To: [log in to unmask]
Subject: [TN] New reflow oven needed for BGAs???
Hi all,
We are looking at placing BGAs. We currently use a 5 zone reflow oven
that
does a great job of soldering all other components. In fact, we only
have a
few profiles which are used on many products.
Is there a need for more zones when going to BGA? Does size BGA size
matter?
Thanks in advance,
Peter
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