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September 1998

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Subject:
From:
Jeff Hempton <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Wed, 23 Sep 1998 12:18:14 -0500
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Tom,
       Well...all kinds of responses to this person's input come to mind,
     and most of which might not be considered politically correct (a good
     sized well-place ball pien hammer for instance,heh-heh). Anyway,
     bottomside (glue) process has been around for MANY yeras, used by lots
     of us folks, billions of boards. There are descent specs for It's use
     in IPC-610B, etc. that may convince him. I am assuming a fair amount
     of leaded joints is making the wave process very cost-effective. You
     did not give a lot of specifics, but I would research the why's of the
     one failure first, before throwing a process change in there...i.e., a
     simple artwork change may solve the problem, without tooling costs &
     process changes. If that is the only problem you had on such a small
     first-time run, congratulations on a good first cut! Anyway, that's my
     $0.02 worth.

Jeff Hempton
United Technology Electronic Controls
______________________________ Forward Header __________________________________
Subject: [TN] Wave solder VS Reflow on bottom side
Author:  Thomas C Han <[log in to unmask]> at Internet
Date:    9/22/98 6:09 PM


Hi all

I have a mixed technology double sided board.  It has about 900
components w/ 250 passive components on bottom.  The total project is for
only 15 boards and 2 boards were manufactured for first article test.
Since the total account was for such small quantity I ran all 15 boards
thru SMT.  The process was:  top side reflow, bottom side epoxy, PTH
insertion, wave.  Problem is that our customer found 1 solder short
across a cap on the bottom side, and so he is questioning my process of
epoxying the bottom side.  Even though he is a manufacturing engineer, he
is not knowledgable in PCB assembly processes.  How can I explane to him
that any failure in a component is wrong, but 1 out of 500 components( 2X
250 on bottom) is an acceptable figure that I do not see a need for
change.  He insists that since his past CM used reflow and then a pallet
thru wave, that that is a superior process.

He also questioned the fact that solder short on that particular location
happened only to 1 board.  And that if I took a systematic process, then
the solder short should exist on both boards.

Fellow Technetters,  tell me how I can deal with such complaints.

Thanks for all your input.


Tom Han
Ardent Systems

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