Meaning
A set of temperature parameters and time intervals used to control the soldering of surface-mount components to a printed circuit board. During automated board assembly, the reflow profile guides the movement of the populated boards through multiple heating zones to melt the solder paste and form reliable electrical joints. Assembly engineers program these temperature curves based on the solder paste alloy and the thermal mass of the components.
This process prevents thermal shock and ensures that all board areas reach the correct melting point.
Thermal Zone
The process starts with a preheat zone to dry the solvent and activate the flux. Next, the board enters a soak phase where the temperature stabilizes across all components of varying sizes. Finally, the board passes through the peak reflow zone where temperatures brief rise above the solder liquidus point.
Solder Integrity
Insufficient peak temperatures can cause cold solder joints that fail during vibration testing. Conversely, excessive heat can damage sensitive silicon or melt plastic connectors on the board.
Oven Control
Convection reflow ovens use conveyor belts to move boards through independent heating chambers at a controlled speed. Multi-channel data loggers record the board temperatures during test runs to verify the settings.