ulpa filter (ultra-low particulate air)

ULPA filters (Ultra-Low Particulate Air) remove 99.999% of particles 0.12 microns and larger, exceeding HEPA for critical semiconductor applications. **Specification**: 99.999% efficiency at 0.12 micron MPPS. U15-U17 grades in European classification. **Comparison to HEPA**: 100x lower particle penetration than HEPA. Catches smaller particles. More expensive. **Use in semiconductors**: Critical lithography areas, advanced node processing, anywhere particles would cause yield loss. **Trade-offs**: Higher pressure drop than HEPA (more energy for airflow), more expensive, faster to load. **Construction**: Similar to HEPA but denser media, more pleats, higher efficiency fibers. May include electrostatic enhancement. **Maintenance**: Monitor pressure drop, replace on schedule or when loaded. More frequent replacement than HEPA expected. **Where HEPA sufficient**: Less critical fab areas, older process nodes, non-lithography processing, gowning rooms. **Selection criteria**: Node size, defect sensitivity, cost/benefit analysis. Advanced nodes (sub-7nm) typically require ULPA. **Integration**: Installed in FFUs, air handlers, process equipment. Sealed frames prevent bypass leakage.