Underfill Rework Process Suggestion
Optimize your underfill rework process with these comprehensive steps
Step 01: Component Stripping
Begin by heating he solder joint to a temperature higher than the reflow temperature to soften the adhesive, minimizing substrate damage. Once the temperature exceeds the solder ball’s melting point (220~240°C), gently rotate or use a vacuum to remove the components. Avoid overheating to prevent substrate damage, as excessive heat may pull out the metal pads.
Step 02: Prepare the Component Holder
Post-removal, follow two methods to clear residue effectively:
- Utilize the scraping method: Heat the soldering iron to 250~300°C to carefully scrape residue, or warm the substrate before using a brush to clean off debris.
- Employ a rotary brush: Apply pressure to remove any remaining primer using a rotary brush, ensuring gentle pressure to prevent substrate damage. The choice between solder paste or flux depends on the component type and solder ball composition.
Step 03: Component Attachment
After substrate cleaning, inspect for residual adhesive using isopropyl alcohol (IPA) or a flux pen. Apply solder paste flux to the substrate, position the new component, utilize a vacuum pick-up tool, perform hot air reflow, and apply primer. Finally, reattach the chip to the PCB, completing the underfill rework process.
