The real-time top-side preheating module is for high-mass assemblies. Promotes draw of solder through barrel to the board’s top side. Provides internal continuous preheat during selective soldering. Can be used as the primary preheating function or to maximize productivity when used in combination with discrete pre-heaters to maintain board temp. during soldering operation. An optical pyrometer reads actual PCB temperature with real-time, closed-loop control.