Characteristics of Ultra-High Efficiency Membrane Filters in Gas Applications

The particle collection characteristics of ultra-high efficiency polyvinylidene fluoride (PVDF) membrane filter media has been evaluated. This media is typical of PVDF and polytetrafluoroethylene (PTFE) media used for process gas filtration in the semiconductor industry. Testing was performed using specially prepared ultra-thin membrane samples since the penetration through the standard production media is less than current detection limits. The data obtained were used to predict the performance of the standard membrane. The calculated aerosol penetration through the standard media ranges between 6 × 10-32 and 4 × 10-23 for face velocities of 5 to 50 cm/sec. The most penetrating particle size was found in the 0.035 to 0.045 μm size range. The effect of particle loading on particle penetration was also studied. The penetration was found to decrease as the filter media was loaded with either liquid or solid particles.