Steve reminds me of another story, also from back in my Vitronics days.
An old friend of mine, Jim Elliot was working for Western Digital back in the
"early days".  A Quadstar developed a placing problem on a QFP (funny how
most of these stories relate to early Quad placement systems).  Suddenly, the
misplaced QFPs started coming out of the oven reflowed in proper alignment.
Seems, the story goes, a boombox had inadvertantly been placed near the
offload of the SMD-722 (convection/IR) oven and had set up a low amplitude
vibration into the reflow section of the oven due to the angle it had been
placed.  This acoustic vibration had aligned the part much in the way a
mechanical device attached to the conveyor might have.  I think Jim pursued
patenting this acoustic vibration but I don't know where it ever went.  It
took me two years to get Jim to tell me what tune was playing.  I won't
reveal this trade secret but if the system had been produced, I think Bob
Segar would be getting royalties.
For the same reason you don't want to use mechanical vibration, don't try
this at home.

Phil Zarrow
ITM Consulting
Durham, NH  USA
www.ITM-SMT.com
Tel: 603-868-1754
Fax: 603-868-3623
EM: [log in to unmask]