Method and apparatus for controlling a time/temperature profile of a reflow oven

Apparatus for controlling solder reflow time and temperature of a component populated substrate, comprising:

• a multi-zone reflow oven having a substrate carrier belt, heating elements means and convection fans,
• belt drive means for controlling the carrier belt speed,
• fan drive means for controlling the convection air flow,
• power means for controlling the temperature of said heating element means,
• said reflow oven having a central controller capable of effecting control of said belt drive means, said fan drive means, and said power means,
• keyboard means coupled to said central controller for setting initial control parameters in said central controller and for creating a desired solder paste temperature profile and deviation set points in each of the zones of said multi-zone reflow oven,
• thermal scanner means coupled to said central controller for thermally scanning a substrate moving through said reflow oven,
• said thermal scanner means comprising an infra red optical device for generating an infra red thermal map of a view of said substrate,
• said central controller having means for determining the actual solder paste temperature at points on said solder paste temperature profile, by analysis of said infra red thermal map, and
• program control means in said central controller for generating feedback control signals for changing one or more of said belt drive means, said fan drive means and/or said power means to effect a desired solder paste temperature at said points scanned by said thermal scanner.