Wave Soldering - Preheating

Preheating

Once fluxed, the PCB enters the preheating zone. The preheating zone consists of convection heaters which blow hot air onto the PCB to increase its temperature. For thicker or densely populated PCBs, an upper preheater might be used. The upper preheater is usually an infrared heater.

Preheating is necessary to activate the flux, and to remove any flux carrier solvents. Preheating is also necessary to prevent thermal shock. Thermal shock occurs when a PCB is suddenly exposed to the high temperature of the molten solder wave.