Water Vapor Transmission Rate

Barrier Selection

Materials with low transmission rates are selected for moisture-barrier bags to extend the shelf life of electronic parts. Aluminum foil layers are laminated with polymer films to create high-performance barriers. These composite sheets prevent moisture from reaching the enclosed drying agents too quickly.

This selection process is critical for parts that must be stored for long periods.

Measurement Standard

Testing is performed using specialized instruments that expose one side of the film to high humidity while measuring the moisture accumulation on the dry side. Standardized test methods such as those from ASTM define the required temperature and humidity levels for the test. The resulting values are used to compare different packaging films.

This standardization ensures that material specs are reliable.

Packaging Integrity

Punctures or seals that are not complete can compromise the barrier and increase the effective transmission rate. Even a tiny pinhole allows moisture to enter the package rapidly, saturating the desiccant. Regular inspection of the packaging seals is required to ensure that the barrier remains intact.

This maintenance is essential to protect components during transportation and long-term storage.