Thermogravimetric Analysis of Flux Solvent Evaporation in Reflow Profiles
Thermogravimetric solvent mass loss below half a percent prior to liquidus eliminates outgassing macro-voids under bottom-terminated components.
Conveyor Speed
Process Velocity
Thermal profiling in printed circuit board assembly relies on the rate of travel of the transport mechanism to establish a consistent temperature exposure for the assemblies. In this environment, conveyor speed dictates the exact dwell time of the printed circuit board within each heating zone of the reflow oven. Adjusting this transport rate determines whether the board receives the correct amount of thermal energy to liquefy the solder paste properly.
It directly governs the ramp rate and the cooling curve of the thermal cycle.
Thermal Balance
Slow transit rates increase the peak temperature of the board and may cause board delamination, pad lifting, or substrate charring. Conversely, high conveyor speed reduces the dwell time, leading to incomplete solder reflow and cold solder joints. Operators calculate the optimal rate based on the board thickness, the thermal mass of the components, and the heating zone lengths.
Operational Tolerance
Sudden variations in the drive motor rate or belt tension will disrupt the thermal equilibrium, leading to defects in the finished solder joints. Modern assembly lines utilize closed-loop feedback systems to maintain the conveyor speed within a tight tolerance of the nominal recipe setting. This control is verified during daily calibration runs to prevent thermal shock in the preheat phase.