Therefore, it is basically not needed. The hot air SMT reflow oven has been in use since the mid-1980s and continues to be relevant today. In recent years, hot air reflow ovens have incorporated various advancements in airflow design, equipment structure, materials, and both software and hardware configurations. As a result, all-hot-air reflow ovens have become the preferred choice for today’s SMT reflow processes.
The infrared hot air reflow oven features heating sources that utilize both hot air and infrared rays. Due to the high soldering temperatures required for lead-free soldering, the reflow zone must enhance thermal efficiency; thus, infrared heaters are added at both the entrance of the hot blast stove and the bottom of the reflow zone. This approach not only addresses the challenges of high soldering temperatures and accelerates the heating rate but also conserves energy. Consequently, infrared hot air stoves have gained a significant foothold in today’s lead-free soldering applications.
The gas-phase reflow furnace was first introduced in the early 1970s, but due to the high costs associated with the equipment and media, it was soon replaced by other methods. However, the gas-phase reflow furnace offers advantages such as precise temperature control, the ability to use heating media with varying boiling points to accommodate different soldering temperatures for various products, high heat conversion efficiency, rapid heating, an oxygen-free environment, uniform temperature distribution across the PCB, and excellent soldering quality. Thus, with the shift towards lead-free soldering, the gas-phase reflow furnace has once again captured interest, particularly for high-reliability and challenging surface mount boards.
2) Reflow oven that locally heats the circuit board
The laser beam reflow oven capitalizes on the exceptional directivity and high power characteristics of laser beams. By concentrating the laser beam in a small area for a brief period through an optical system, a highly concentrated local heating zone is created at the solder joint. During the soldering process, both the substrate and component bodies remain at lower temperatures, minimizing soldering stress and preventing damage to components and the substrate. However, due to the high cost of this equipment, it is primarily utilized for thermal components, precious substrates, and fine-pitch local soldering of components.
Focused infrared reflow ovens are generally suitable for rework stations, designed for rework or partial soldering. A hot air flow reflow furnace is a type of reflow oven that introduces air or nitrogen into a specialized heating head, using hot air flow for soldering. This kind of SMT reflow oven requires processing nozzles of various sizes to accommodate different solder joint dimensions and operates at a relatively slower speed, making it mainly suitable for rework or developmental purposes.
