Lord Kelvin would advocate thermal profiling, for only by profiling do we have any idea of what is actually occurring in a reflow soldering process. With the increasing complexity of modern surface mounted assemblies, those process windows are narrowing and the margin of error at each stage is decreasing thereby increasing the necessity of process accuracy and stability at each step. The Printed Circuit board - which can be made of a variety of materials, FR4 is common.
Solder paste is made up of small solder balls and flux.
The flux is an inert solid at room temperatures and turns to liquid and becomes active at an elevated temperature. Heat Transfer Device - the oven, usually with controllable temperatures in multiple zones, adjustable conveyor speed and convective heat transfer. The Mechanics of Profiling Thermocouples Type K thermocouples are most commonly used in the electronics industry. The method of attaching the thermocouple to the assembly to be profiled can be specific to the assembly and situation as well as preference of the user. Attachment High Temperature Solder provides a very robust physical connection to the pcb.