What is importance of the reflow profile?
Reflow soldering is an assembly process for printed circuit boards (PCBs) in which surface-mount parts are placed on a PCB prepared with solder paste.  The solder is melted by heating in a temperature-controlled oven, which then electrically connects component leads to pads on the PCB.  ICs can be damaged by high temperatures/rapid changes in temperatures, so the thermal profile defines the acceptable limits on the temperature of the reflow to avoid damaging the component.