Filter Contamination Testing with the Chem 20 Particle Counter

Filter Contamination Testing with the Chem 20 Particle Counter

Effective particle filtration is key to controlling contamination in high-purity chemicals. Over time, the performance of filters can degrade due to wear and tear on the filter membranes. Filters need to be replaced every so often according to the manufacturer’s recommendations to avoid contamination. Before a new filter can be installed into a chemical system, the filter membranes are wetted by flowing liquid through the filter using a low surface-tension fluid (IPA or water). Then they’re flushed with UPW to remove the IPA and any residual particle contamination.

In this study, the Chem 20 chemical particle counter from Particle Measuring Systems (PMS) was placed inline with a dedicated filter-wetting machine used by a semiconductor manufacturer to wet and flush new particle filters before they are used in production.

Two new particle filters with filtration ratings of 2 nm and 15 nm were tested using this particle counter system, with the contamination concentration downstream of each filter measured by the Chem 20 particle counter for more than 24 hours. The results are shown below.

In both cases of monitoring with a 20 nm chemical particle counter, the filters released a significant amount of particle contamination during the initial wetting period, after which the particle concentration gradually decreased.

  • The 15 nm filter contained a much greater number of sub-70 nm particles than the 2 nm filter and took significantly longer to stabilize at a baseline particle level. The 15 nm filter took over twelve hours to stabilize at the baseline level.
  • The 2 nm filter was already reasonably stable after around four hours, and stabilized at a much lower particle concentration.

What this tells us is: Real-time particle counting data can be used to establish an efficient filter wetting protocol to ensure filters are sufficiently clean before their use in the production process.

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