Issue link: https://iconnect007.uberflip.com/i/1546025
44 SMT007 MAGAZINE I AUGUST 2026 nitrogen through a nozzle to concentrate heat around a specific component. Infrared rework uses radiant energy to heat the component and surrounding area without forced airflow, often providing broader heat exposure. Both types of systems commonly include bottom- side preheating, adjustable board supports, compo- nent alignment or placement features, and thermo- couple monitoring. These controls help develop and repeat a thermal profile that brings the solder joints to reflow temperature without unnecessarily overheating the component, PCB, or adjacent parts. Both hot air and infrared systems are accepted rework methods, but neither is the best choice for every assembly. The appropriate method depends on factors such as component construction, PCB thermal mass, surrounding component density, surface finishes, accessibility, and production requirements. The following sections compare the advantages and limitations of each method. Pros: Hot Air Targeted heat exposure: Hot air rework is a widely used and accepted method for reworking ball grid array (BGA) packages because it provides local- ized heating through a targeted nozzle. Nozzles are designed to fit closely around the component perim- eter, helping focus heat on the target package while improving access in densely populated assemblies and limiting thermal exposure to nearby compo- nents, connectors, and other heat-sensitive features. Less affected by surface finishes: Another benefit of hot air rework is its ability to accommodate component packages made from a wide variety of materials, colors, and surface finishes. Packages with higher thermal mass, such as ceramic or metal packages, generally require more time and energy to reach reflow temperature than plastic packages. However, hot air heating is typically less affected by differences in surface color, emissivity, and reflec- tivity than infrared heating. Repeatable process control: Hot air rework systems provide repeatable process control by allowing key variables such as nozzle temperature, airflow, bottom-side preheat, and profile timing to be adjusted and documented. Thermocouples can be used to monitor actual temperatures at the compo- nent, solder joints, PCB surface, and underside of the board throughout the heating cycle. Once a successful thermal profile is developed, the same process parameters can be saved and repeated on similar assemblies. This improves consistency while reducing the risk of overheating, insufficient reflow, and unnecessary thermal exposure. Pros: Infrared Broad, uniform heating: Infrared rework systems apply radiant energy across a wider area, which can help heat the component and surrounding PCB more gradually and evenly. This broader heating approach may reduce steep temperature differences across large components or high-thermal-mass assemblies when the process is properly profiled. Airflow-free rework: Because infrared systems transfer heat without forced air, they eliminate the risk of airflow disturbing small, lightweight compo- nents near the rework site. This can be beneficial in densely populated assemblies containing chip components, fine-pitch devices, or other parts that could shift during reflow. Reduced dependence on custom nozzles: Infrared systems can accommodate a wider range of component sizes and shapes without requiring a dedicated nozzle for every package. This may reduce setup time and tooling costs, particularly for low-volume work or assemblies containing unusual component geometries. Faster heating for production work: Infrared systems can heat the component and surrounding PCB more quickly by transferring radiant energy across a broad area at the same time. This can shorten cycle times and improve throughput for repeat production work, particularly when the assembly has consistent mate- rials, surface finishes, and thermal characteristics. Cons: Hot Air Risk to adjacent components: Although a targeted nozzle limits the heated area, escaping airflow and radiant heat from the nozzle can still affect nearby components, connectors, or plastics. Improper K N O C K I N G D OW N T H E B O N E P I L E