2026-08-05
Solution: Huitian 6631H Single-Component Underfill Epoxy
After evaluating six underfill candidates from both international and domestic suppliers, the engineering team selected Huitian 6631H, a single-component, heat-curing epoxy underfill specifically formulated for CSP/BGA protection and FPC (Flexible Printed Circuit) reinforcement. The decision was driven by four key performance attributes:
| Performance Dimension | 6631H Specification | Operational Benefit |
|---|---|---|
| Rapid Capillary Flow | Viscosity ~600 mPa·s | Complete underfill of 0.3mm-pitch BGA within 8 seconds; compatible with automated dispensing nozzle |
| Fast Cure Cycle | 130°C / 10 minutes | Matched existing reflow profile window; eliminated need for dedicated curing ovens |
| Thermomechanical Stability | Storage modulus ~4,000 MPa (-40°C to 150°C) | Uniform stress distribution across the entire adhesive layer, preventing localized solder joint overload |
| Rework Compatibility | Engineered rework profile | Field-failed BGA packages successfully removed and replaced without pad lift or PCB delamination |
Process Integration
6631H was deployed across three production lines, targeting:
The curing step was integrated into the existing inline oven profile at 130°C for 10 minutes, requiring zero additional floor space or cycle-time adjustment.
Results
The OEM's VP of Manufacturing Engineering noted: "6631H solved the fundamental contradiction between reliability and manufacturability that we struggled with for two product generations. The fast flow and cure profile meant we could add underfill protection without slowing the line, and the reworkability eliminated the fear of scrapping expensive assembled boards."
