Rob,
  One of the reasons most people process topside reflow first, then bottomside
(glue) is because many people also auto-insert leaded parts after top-side,
before bottomside glue/SMD placement, and the auto-insert process really hammers
the board and there are chances of losing the glued parts. If you have the
luxury of having all hand-placed leaded parts and wanted to do bottomside first,
the reflow temps should not damage the glue. If your glue process is
really-really dense on the backside, and you have fine pitch on the topside,
getting adequate board support could be an issue.
  Also, if you have the luxury of only hand placed leaded parts, I hope you are
taking advantage of the ability to stencil adhesives instead of dispensing.
Regards.
Jeff Hempton
United Technology Electronic Controls

______________________________ Forward Header __________________________________
Subject: [TN] Smt process
Author:  [log in to unmask] at Internet
Date:    3/17/1999 10:24 AM


We are in the process of determining the most efficient way to run our smt
process.  Right now we only have a half line and are looking at adding the
back half of the line.  Our current process takes us through reflow first,
flip the product, then move the product to the beginning of the line and
then run the bottom side (curing).  If we use this current process with the
second half of the line, we will need to flip the product over before it
reaches the hand insertion line.  Our thoughts are can we run bottom
(curing) first, flip the product, and then run top side (reflow)?  This
will require us to only flip the product once.  Are there any issues with
running curing first and then running reflow?  After the glue is cured, it
will be passing through the oven during reflow at a higher temperature than
the curing temperature.  Will the reflow temperature have any effect on the
glue?

Rob Williams

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