Reflow soldering equipment is a fundamental part of the SMT production line. It is also called re-flow soldering and works by remelting solder that has been pre-applied to the PCB pads, forming mechanical and electrical connections between component leads or terminations and the board. Before reflow soldering, solder paste is printed onto the PCB pads by a screen printer, components are placed onto the corresponding positions by a pick-and-place machine, and the assembled PCB is then sent into the reflow oven. The solder paste undergoes drying, preheating, melting, wetting, and cooling to solder the components onto the board.
Reflow soldering equipment generally has two basic structural types: single-zone reflow ovens and multi-zone reflow ovens.
Single-Zone Reflow Oven
In a single-zone reflow oven, the temperature of the heating zone changes over time according to the reflow temperature profile, while the PCBA remains stationary inside the chamber. The advantages of this type include low investment and easy tracking of the set temperature profile. The disadvantages are that the temperature changes periodically, resulting in longer production cycles and higher energy consumption. It is generally suitable for single-piece or small-batch production.
Multi-Zone Reflow Oven
A multi-zone reflow oven divides the furnace into several temperature zones based on the reflow temperature profile. The PCB moves at a constant speed through each zone, completing the preheating, reflow, and cooling stages in sequence.
The main characteristic of multi-zone reflow ovens is that each zone has relatively independent constant-temperature control, and the control algorithm is simpler. The greatest advantage is high efficiency, making the equipment suitable for industrial high-volume continuous production. However, the physical separation between zones creates certain temperature differences, which can cause thermal shock and thermal stress to the board. Using more zones can reduce these temperature differences. For non-standard zone dividers, conveyor rails, or custom board carriers used to improve temperature uniformity in multi-zone ovens, Hansheng Automation can provide precision machining based on customer drawings.
Because reflow soldering has the characteristics of "re-flow" and "self-alignment," the requirements for the preceding placement process can be relaxed. Reflow soldering also offers good joint quality, lower solder consumption, and consistent product quality. These advantages make reflow soldering equipment the mainstream and key equipment in the SMT assembly process.
