AMC and PTFE Filter Case Study

In high-tech cleanrooms, traditional glass fiber HEPA/ULPA filters exposed to AMC-containing environments for long periods may experience fiber degradation or release boron (Boron) and other dopants, paradoxically becoming a cleanroom risk. PTFE (polytetrafluoroethylene) filters, due to their superior chemical inertness and low outgassing characteristics, have gradually become the preferred solution for advanced process cleanrooms.

A domestic semiconductor packaging and testing facility discovered during process upgrade that the original glass fiber ULPA filters showed efficiency degradation after only 8 months of use in acidic etching areas (Wet Etch Bay). Particle counters measured 0.1μm particle counts rising from the designed value of 1 particle per cubic foot to above 5 particles. With Baisheng Technology's analysis assistance, we confirmed this was caused by HF and HCl acidic gases eroding glass fiber adhesive.

We recommended the customer replace all FFU filters in that area with PTFE membrane filters. PTFE filters use microporous thin film structure, different from traditional depth filtration of glass fiber filters. Their filtration mechanism is surface filtration, offering the following advantages: First, excellent chemical inertness, resistant to acids, bases, and organic solvents. Second, low pressure drop design—at equivalent efficiency, pressure drop is approximately 20-30% lower than glass fiber filters, reducing fan energy consumption. Third, free of adhesive, will not release boron or silica and other dopants (MD-class AMC).

Post-replacement tracking data showed the area maintained particle counts below 0.5 particles per cubic foot (ISO Class 3 level), and after 18 months of operation, pressure drop increased only 12 Pa, far below the 35 Pa increase typical for glass fiber filters over the same period. For the facility's 120 FFU units, annual electricity savings reached approximately NT$450,000. This case fully demonstrates that in process areas with more stringent chemical environments, while PTFE filters have higher initial investment, when comprehensively evaluating service life, energy consumption, and cleanroom stability, the long-term total cost of ownership (TCO) is actually more advantageous.