I suppose you could look at it from a cost stand point.  If the customer is
willing to pay for the cost of the pallet, go for it.  Otherwise, for 15
boards I wouldn't spend the extra on a solder pallet or the solder stencil
for the bottom side.  Your original process method is still very valid.  A
good ICT test should have picked up on the short failure.




Thomas C Han <[log in to unmask]> on 09/22/98 08:09:10 PM

Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond
      to Thomas C Han <[log in to unmask]>

To:   [log in to unmask]
cc:    (bcc: Andrew G Kettlewell/PGG/Cummins)
Subject:  [TN] Wave solder VS Reflow on bottom side




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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