Steve,

It appears that you have several options.  One would be to change to an
alternate board finish, such as an OSP, immersion gold, palladium, etc,
which all have very flat surfaces.  HASL  thicknesses vary considerably,
especially those processed vertically.  A "typical" HASL specification is
something like .00008" minimum to .002" maximum.  If you're seeing ranges
outside those, perhaps the HASL process can be improved.

Another option may be to find an epoxy with a higher green strength, in
order to hold the components more consistently before curing.  Or is the
mis-location actually due to the surface finish at all, or is it that big
crack in the concrete that the operators roll the cart over on their way to
the curing oven?  Or the servo ramp rate of the movable worktable on your
placement table... Or.... Or...

Just some thoughts.

Larry Morse
Celwave RF


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 ------------------------ INTERNET MAIL ------------------------
From:           Steve Collins <[log in to unmask]>
Subject:        [TECHNET] SMT Coplanarity issues