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January 1998

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Subject:
From:
Bev Christian <[log in to unmask]>
Reply To:
TechNet Mail Forum.
Date:
Tue, 6 Jan 1998 16:10:52 -0500
Content-Type:
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Krishna,
Joe Belmonte and Phil Zarrow give a formula for determining the maximum
weight of a secondary side SMT component in an article in Circuits
Assembly, September 1996.  The formula is: Weight of component in
grams/Total pad mating area in square inches must be less than 30.
Perhaps your part is too heavy?  Or is this a component that you have
been soldering successfully for some time, but can't do now?  Has your
process changed (higher temperature, less surface tension), higher air
flow in oven, conveyor shudder?  Good luck.

Bev Christian
Nortel
>----------
>From:  Krishna Kalyan[SMTP:[log in to unmask]]
>Sent:  Tuesday, January 06, 1998 10:15 AM
>To:    [log in to unmask]
>Subject:       [TN] Lead Soderability - second reflow
>
>Hello :
>
> Happy New Year to all of you.
>
> I am a process engineer trying to resolve the falling of a bottom side
>surface mount component during second pass of forced convection reflow.
>I am beginning to feel that the solderability of the component leads is
>getting reduced after the first pass of reflow and that is causing the
>part to fall. If any of you have had similar experiences, could you
>please share ? Your suggestions are welcome.
>
>Krishna Kalyan
>
>
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