I would concur with S. Ng, that a Vitronics 310 with 4 top and 3   
bottom zones will have a hard time to controlling the "time above liquidus"
  
as well as uniformity. A forced convection oven with more zones allows much
better control and uniformity. 
However, there is no such thing as a 'pure Infrared' oven; in so-called "IR
Reflow Ovens" in access of 50% of the heat transfer is by convection,
depending on the zone. Likewise, in "Forced Convection Reflow Ovens" up to
25% of the heat transfer is by radiation, depending on gas flow and platen
temperature. 

Werner Engelmaier
Engelmaier Associates, Inc.
Electronic Packaging, Interconnection and Reliability Consulting
23 Gunther Street
Mendham, NJ  07945  USA
Phone & Fax: 201-543-2747
E-Mail: [log in to unmask] 

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