| I like to know under what conditions the reflow profile of a solder paste is taken? Bare board, board with the solder paste, or board with high melt solder paste? | John: None of the above. The two key variables that determine the reflow temperature profile of a specific PCA are:
1 The characteristics of the paste being used to bond components to the board 2 The peculiarities of that assembly.
So, paste your board, place the components, and measure your profile during reflow. Place your thermocouples:
1 On the leading and trailing edges of the PCA 2 At the largest and smallest components and on a ball of each BGA 3 On board fab areas with large thermal masses
Check-out the sites of the profiler manufacturers (ie, KIC, ECD, Super Mole, etc). Some of them provide good information.