Before every line changeover, the chamber of the Jia Jinyuan reflow oven must be thoroughly cleaned, with special attention to the slit area at the junction of the central heating zone and the cooling inlet. This location has low airflow disturbance and a large temperature gradient, making it highly prone to depositing tar-like residues from Flux cracking. If not removed in time, these residues will be carried by airflow during subsequent reflow passes and adhere to the PCB surface, forming local yellow spots or excessive ionic contamination. When cleaning, first lower the oven temperature below 80°C before shutting off the nitrogen supply. Use residual heat in combination with a dedicated non-woven cloth dipped in 75% isopropyl alcohol for repeated wiping. Hard scrapers are strictly prohibited to avoid scratching the ceramic coating on the inner chamber walls, which would accelerate local oxidation and cause uneven infrared radiation.

During daily inspections, the mesh belt operation status and the liquid accumulation color in the oil drip pan at the bottom of the chamber must be observed simultaneously. If an increase in pale yellow viscous liquid is found, it indicates insufficient flux volatilization or nitrogen purity has dropped below 99.99%. At this point, immediately verify whether the solid content setting of the upstream spray fluxer is too high and whether the preheat zone temperature ramp rate is below 1.2°C/s. Mismatches in these two parameters directly cause the flux to fail to complete effective activation and solvent evaporation before entering the reflow zone. A large amount of undecomposed components enter the high-temperature zone with the PCB, rapidly carbonize, and adhere to the surface of the chamber refractory bricks.

Deep chamber cleaning must be performed at least once a week. The upper and lower furnace door sealing strips of the Jia Jinyuan reflow oven need to be removed, and compressed air should be used to purge the chamber cavity from both ends toward the center, focusing on cleaning the blind areas between the chain rails and the nozzles. Micron-level carbon powder that has accumulated in these positions over time will resuspend under airflow disturbance. Once mixed into the cooling air duct, it may be blown onto the surface of just-solidified solder joints, forming particulate contamination. If the static elimination brush at the cooling section outlet is heavily dusted, it will also reduce static removal efficiency, indirectly exacerbating dust adsorption on the board surface. After cleaning is completed, a white glove must be used to slide along the entire length of the mesh belt for inspection. The glove is considered qualified only if there is no obvious staining; otherwise, repeat cleaning until the standard is met.

When the production line frequently switches between high-lead and lead-free processes, the cleaning cycle must be shortened. This is because lead-free solder corresponds to higher peak temperatures (typically 235°C~245°C), which causes traditional rosin-based flux to crack into irreversible carbides more quickly. After repeated heating in the chamber, these residues form a dense hard shell that can no longer be removed by alcohol wiping alone. It must be gently polished with a 200-grit silicon carbide soft abrasive pad. However, the polishing force must be controlled such that a single pass does not exceed 3 seconds; otherwise, the protective sleeve of the built-in K-type thermocouple temperature measurement probe of the Jia Jinyuan reflow oven may be damaged, leading to delayed temperature control feedback and subsequently causing batch cold solder joints.

All cleaning records must be filled out in real time on the workshop paper inspection sheet, including the cleaner's name, start and end times, batch numbers of consumables used, and a comparison of infrared thermal images of the chamber before and after cleaning. Abnormal areas in the images must be marked with coordinates and simultaneously reported to equipment engineers for review. This is because changes in local chamber emissivity often appear before temperature drift occurs, making it the most sensitive leading indicator for judging the aging degree of heating elements. Ignoring this point will allow preventable temperature zone runaway to escalate into cold solder joint rework for an entire batch of PCBs.