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.

By following these meticulous steps, you can ensure efficient and reliable underfill rework, minimizing risks and maximizing the quality of reworked components.

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