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July 2001

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Mon, 23 Jul 2001 12:05:56 -0400
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Formula = weight of component in grams/total pad mating area in square
inches

The resulting grams per sq. in. must be less than or equal to 30.

This formula came by way of Phil Zarrow from his article on Reflow Soldering
of Through-Hole Components (Journal of SMT, Oct. 1999.)


Bob


Robert Barr
Manufacturing Engineering
Formation, Inc.
Voice: 856-234-5020 x3035
Fax: 856-234-6679

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Stephen Brown
Sent: Monday, July 23, 2001 11:02 AM
To: [log in to unmask]
Subject: [TN] Component Mass / Pad Geometries


Question?

There is a formula somewhere which I can use to calculate the maximum
allowable mass of a component in relation to the pad lands. Basically I
want to make sure our designers do not put components on the underside
of the PCB which are going to fall off during doublesided reflow.

I would like to point out that this is a design for manufacturability
question, not an attack on the tentative grasp on reality some card
designers have.

Steve.

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