In SMT chip processing, reflow soldering is commonly used to solder a large number of surface mount components (SMA). The heat transfer methods for reflow soldering can be categorized into three main types: far infrared, full hot air, and infrared/hot air reflow. Each method has its own advantages and drawbacks, and the choice of method depends on the specific requirements of the soldering process.

1. Far-Infrared Reflow Soldering:
   Far-infrared reflow soldering, first utilized in the 1980s, is known for its fast heating, energy-saving features, and stable operation. However, the uneven temperature distribution among different components and circuit parts due to varying heat absorption rates can lead to local temperature differences. This could result in overheating of certain components and virtual welding due to insufficient heating in other areas.
2. Full Hot Air Reflow Soldering:
   Full hot air reflow soldering, which gained popularity in the 1990s, employs convection jet nozzles or heat-resistant fans to circulate airflow for heating the soldered parts. This method overcomes the local temperature difference and shielding effect encountered in far-infrared reflow soldering, making it widely used. However, the high convective velocity of the circulating gas can cause printed board jitter and component displacement, as well as a relatively low heat exchange efficiency and higher power consumption.
3. Infrared/Hot Air Reflow Soldering:
   Infrared/hot air reflow soldering combines the use of infrared furnace and hot air to achieve a more uniform temperature distribution within the furnace. This method effectively leverages strong infrared penetration, high thermal efficiency, and power-saving characteristics while overcoming the limitations of local temperature difference and shielding effect encountered in far-infrared reflow soldering, making it the most commonly used reflow soldering method in current practice.
   Recent Developments:
   Recent advancements in SMT chip processing include the emergence of fine-pitch assembly technology and nitrogen-protected reflow ovens, which help prevent oxidation, improve welding wetting ability, and reduce solder beads, especially suitable for no-clean processes.