Reflow soldering of solder paste is a critical process in the surface mount assembly of printed circuit boards (PCBs). Infrared (IR) radiation and/or forced convection are often used in an oven to heat the PCB assembly and the deposited solder paste to cause the solder to reflow and subsequently form the interconnection between the component terminations and the attachment pads. Control of the reflow soldering process requires the understanding and regulation of several complex variables. Understanding the interrelationships among process control parameters is important in achieving a low defect rate and high yields in reflow soldering. When a variety of components are soldered onto a printed circuit board (PCB) simultaneously in an IR/convection oven through reflow soldering, the process control variables that need to be considered include the characteristics of solder paste used, the size, type, and quantity of components placed on the PCB, the substrate used, the mass and the thermal area of the workpiece, and the conveyor speed.